United States
Department of
Commerce
National Oceanic and Atmospheric Administration
Environmental Research Laboratories
Seattle WA 98115
United States
Environmental Protection
Agency
Research and Development
Office of Energy. Minerals, and
Industry
Washington DC 20*80
EPA-600/7-78-126
July 1978
Seasonal Distribution,
Trajectory Studies, and
Sorption Characteristics
of Suspended Particulate
Matter in the Northern
Puget Sound Region
Interagency
Energy/Environment
R&D Program
Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1 Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
-------
SEASONAL DISTRIBUTION, TRAJECTORY STUDIES, AND
SORPTION CHARACTERISTICS OF SUSPENDED PARTICULATE
MATTER IN THE NORTHERN PUGET SOUND REGION
by
Edward T. Baker, Joel D. Cline, Richard A. Feely, and Joyce Quan
Pacific Marine Environmental Laboratory
Environmental Research Laboratories
National Oceanic and Atmospheric Administration
7600 Sand Point Way N.E.
Seattle, Washington 98115
Prepared for the MESA (Marine Ecosystems Analysis) Puget Sound
Project, Seattle, Washington in partial fulfillment of
EPA Interagency Agreement No. D6-E693-EN
Program Element No. EHE625-A
This study was conducted
as part of the Federal
Interagency Energy/Environment
Research and Development Program
Prepared for
OFFICE OF ENERGY, MINERALS, AND INDUSTRY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
February 1978
UNITED STATES
DEPARTMENT OF COMMERCE
Juanita M. Kreps. Secretary
NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION
Richard A Frank. Administrator
Environmental Ressaich
laboratories
Wilmol N Hess Director
-------
Completion Report Submitted to
PUGET SOUND ENERGY-RELATED RESEARCH PROJECT
MARINE ECOSYSTEMS ANALYSIS PROGRAM
ENVIRONMENTAL RESEARCH LABORATORIES
by
Pacific Marine Environmental Laboratory
Environmental Research Laboratories
National Oceanic and Atmospheric Administration
7600 Sand Point Way N.E.
Seattle, Washington 98115
This work is the result of research sponsored by the Environmental
Protection Agency and administered by the Environmental Research
Laboratories of the National Oceanic and Atmospheric Administration.
The Environmental Research Laboratories do not approve, recommend,
or endorse any proprietary product or proprietary material mentioned
in this publication. No reference shall be made to the Environmental
Research Laboratories or to this publication furnished by the
Environmental Research Laboratories in any advertising or sales
promotion which would indicate or imply that the Environmental
Research Laboratories approve, recommend, or endorse any proprietary
product or proprietary material mentioned herein, or which has as its
purpose an intent to cause directly or indirectly the advertised
product to be used or purchased because of this Environmental Research
Laboratories publication.
n
-------
CONTENTS
Figures v
Tables ix
Abstract xi
1. Introduction 1
1.1 General Statement 1
1.2 Objectives 2
2. Geography, Physical Oceanography, and Hydrology 4
2.1 Physiographic Setting 4
2.2 Circulation Patterns and Hydrography 4
2.3 River Runoff and Sediment Discharge 6
3. Conclusions 12
3.1 Suspended Matter Distributions 12
3.2 Suspended Hydrocarbons 12
3.3 Oil-Sediment Interaction Studies 13
3.4 LANDSAT Imagery 13
4. Recommendations . . . .' 15
4.1 Suspended Matter Distributions 15
4.2 Characterization of Suspended Hydrocarbons 15
4.3 Oil-Sediment Interaction Studies 16
4.4 LANDSAT Studies 16
5. Suspended Matter Distributions 17
5.1 Station Locations and Sampling Rationale 17
5.2 Observational Procedures 19
5.3 Results and Discussion 22
5.3.1 Suspended Particulate Matter Concentrations -
Areal Distributions 22
5.3.1.1 Seasonal surface values 22
5.3.1.2 Seasonal near-bottom values 22
5.3.2 Suspended Particulate Matter Distribution -
Seasonal Nephelometer Transects 22
5.3.2.1 Transect A (sta. 4-7) 26
5.3.2.2 Transect B (sta. 11-15) 26
5.3.2.3 Transect C (sta. 17-21) 26
5.3.2.4 Transect D (sta. 24-27) 30
5.3.3 Suspended Particulate Matter Distribution -
Time Series Measurements 32
5.3.3.1 Strait of Juan de Fuca (sta. 9/10) 32
5.3.3.2 Deception Pass (sta. 15) 32
5.3.3.3 Cherry Point (sta. 17) 37
5.3.3.4 Fraser River (sta. 26) 37
iii
-------
5.3.4 Suspended Participate Matter - X-ray Mineralogy ... 37
5.3.5 Particle Size Distributions 44
5.4 Sumnary 44
6. Oil-Sediment Interactions 46
6.1 General Statement 46
6.2 Laboratory Study 47
6.3 Methodology 47
6.3.1 Petroleum Hydrocarbon Analysis 47
6.3.2 Oil Recovery Efficiency 48
6.3.3 Sediment-Sea Water Organic Matter Corrections .... 49
6.3.4 Sediment Morphology and Compositional
Characteristics 50
6.4 Results 57
6.4.1 Skagit River Sediments 57
6.4.2 Fraser River Sediments 62
6.5 Discussion 64
6.6 Summary 67
7. Natural Distributions of Hydrocarbons on Suspended Matter .... 68
7.1 General Statement 68
7.2 Field Studies 69
7.3 Methodology 69
7.3.1 Sample Collection 69
7.3.2 Sample Preparation and Analysis 70
7.4 Results 73
7.4.1 Field Sampling 73
7.4.2 Suspended Hydrocarbons - MESA I 73
7.4.3 Suspended Hydrocarbons - MESA II 76
7.4.4 Suspended Hydrocarbons - MESA III 82
7.5 Discussion 87
7.6 Summary 90
8. LANDSAT Imagery 91
8.1 Introduction 91
8.2 Seasonal Variations 93
8.3 Tidal Variations 103
8.4 Summary and Conclusions 105
Acknowledgments 107
Bibliography 108
Appendix A Seasonal Distributions and Abundances of Low
Molecular Weight Aliphatics in the Waters of
Northern Puget Sound 114
A.I Introduction 115
A. 2 Methodology ] 116
A.3 Results and Discussion 116
A. 3.1 LMWH - MESA I * us
A.3.2 LMWH - MESA II ' 123
A.3.3 LMWH - MESA III \ 123
A. 4 Summary 132
IV
-------
FIGURES
Number Page
2.1 Physical setting of the study region 5
2.2 Monthly range, mean, and standard deviation of:
a. water discharge and b. suspended sediment
discharge for the Fraser River at Hope, B.C.
for the period from January 1967 through
September 1977 8
2.3 Monthly mean discharge of water and suspended
sediments of the Skagit River at Mt. Vernon
during 1975 11
5.1 Station locations for MESA I, II, and III. Light
scattering measurements were made at all stations 18
i
5.2 Scatter plot of nephelometer data versus particulate
concentration in the study area 20
5.3 Scatter plot of nephelometer data versus particulate
concentration for some Gulf of Mexico samples
collected simultaneously with the light scattering
measurements 21
5.4 Concentration contours (mg/1) of particulate matter
for surface and near bottom samples from MESA I 23
5.5 Concentration contours (mg/1) of particulate matter
for surface and near bottom samples from MESA II 24
5.6 Concentration contours (mg/1) of particulate matter
for surface and near bottom samples from MESA III 25
5.7 Light scattering values, Transect A 27
5.8 Temperature values (°C), Transect A 28
5.9 Light scattering values, Transect B 29
5.10 Temperature values (°C), Transect B 30
5.11 Light scattering values, Transect C 31
-------
Number
5.12 Temperature values (°C), Transect C 33
5.13 Light scattering values, Transect D 34
5.14 Temperature values (°C), Transect C 35
5.15 Time series light scattering measurements,
station 9/10A 36
5.16 Time series light scattering measurements,
station 15 38
5.17 Time series light scattering measurements,
station 17 39
5.18 Time series light scattering measurements,
station 26 40
5.19 Coulter Counter particle size distributions
from six centrifuge samples 45
6.1 Evaporative weight loss of Prudhoe Bay crude oil 48
6.2 Suspended matter recovery system 51
6.3 Scanning electron micrographs of Skagit River
suspended matter showing particles recovered in
the ambient water (a) and in the effluent from
the centrifuge (b) 54
6.4 Scanning electron micrographs of Fraser River
suspended matter showing particles recovered in
the ambient water (a) and in the effluent from
the centrifuge (b) 56
6.5 Concentration of accommodated Prudhoe Bay crude
oil (La) on Skagit River suspended sediments as
a function of the initial oil loading (L0) 59
6.6 Gas chromatogram of the extracted aliphatic
fraction taken from oil flocculated sediments 60
6.7 Gas chromatogram of the aliphatic fraction of
Prudhoe Bay crude oil 61
6.8 Concentration of accommodated Prudhoe Bay crude oil
(L.) on Fraser River suspended sediments as a
function of the initial oil loading (L0) 63
VI
-------
Number Page
7.1 Chromatograms of the (a) alkane standard (ALK-9)
and (b) the arene standard (PAH-6) 72
7.2 Gas chromatogram of the saturated hydrocarbon
fraction from station 15 75
7.3 Gas chromatograms of the (a) saturated and
(b) unsaturated fraction from station 9 located
near Port Angeles (MESA-II) 78
7.4 Gas chromatograms of the (a) saturated and
(b) unsaturated fractions from station 17
located near Cherry Point (MESA-II) 81
7.5 Gas chromatograms of the (a) saturated and
(b) unsaturated fractions from station 17
located near Cherry Point (MESA-III) 83
7.6 Gas chromatograms of the (a) saturated and
(b) unsaturated fractions from station 26
located near the mouth of the Fraser River
(MESA-III) 86
8.1 MSS Band 5 of LANDSAT image 1169-18373 on
Jan. 8, 1973 between slack water and major
ebb current 94
8.2 MSS Band 5 of LANDSAT image 1187-18374 on
Jan. 26, 1973 95
8.3 MSS Band 4 of LANDSAT image 2417-18220 on
Mar. 14, 1976 96
8.4 MSS Band 5 of LANDSAT image 2111-18254 on
May 13, 1975 97
8.5 MSS Band 5 of LANDSAT image 2129-18254 on
May 31, 1975 98
8.6 MSS Band 5 of LANDSAT image 1727-18290 on
' July 20, 1974 99
8.7 MSS Band 5 of LANDSAT image 5465-17484 on
July 27, 1976 100
8.8 MSS Band 4 of LANDSAT image 2921-18025 on
July 31, 1977 101
8.9 MSS Band 5 of LANDSAT image 2957-18004 on
Sept. 5, 1977 102
vi i
-------
Number
Appendix
A.I Locations selected for seasonal LMW hydrocarbon
observations
A.2 Areal surface distribution of dissolved methane
(n*/£, STP) during 16-22 Nov. 1976 (MESA-I) 119
A.3 Distribution of dissolved methane (n£/fc, STP)
within 5 m of the bottom during 16-22 Nov. 1976
(MESA-I) 120
A.4 Areal surface distribution of dissolved ethane
(ni/£, STP) during 16-22 Nov. 1976 (MESA-I) 121
A.5 Areal surface distribution of dissolved ethene
(n£/fc, STP) during 16-22 Nov. 1976 (MESA-I) 122
A.6 Areal surface distribution of dissolved methane
(r\l/l, STP) during 10-17 Mar. 1977 (MESA-II) 124
A.7 Distribution of dissolved methane (ni/A, STP)
within 5 m of the bottom during 10-17 Mar. 1977
(MESA-II) 125
A.8 Areal surface distribution of dissolved ethane
(ni/l, STP) during 10-17 Mar. 1977 (MESA-II) 126
A.9 Areal surface distribution of dissolved ethene
(ni/£, STP) during 10-17 Mar. 1977 (MESA-II) 127
A.10 Areal surface distribution of dissolved methane
(n£/i, STP) during 8-14 Aug. 1977 (MESA-III) 128
A.11 Distribution of dissolved methane (ni/t, STP)
within 5 m of the bottom during 8-14 Aug. 1977
(MESA-III) 129
A.12 Areal surface distribution of dissolved ethane
(ni/i, STP) during 8-14 Aug. 1977 (MESA-III) 130
A.13 Areal surface distribution of dissolved ethane
(ni/l, STP) during 8-14 Aug. 1977 (MESA-III) 131
A.14 The area! surface ethane/ethene ratio (C2-o/C2-i)
during 8-14 Aug. 1977 (MESA-III) ....!..' 133
viii
-------
TABLES
Number Page
2.1 Average annual runoff from the major rivers
discharging into the study region 7
2.2 Comparison of water and sediment discharge for
the Fraser and Skagit Rivers during period of
record (1967-1976) 9
5.1 X-ray mineralogy of selected water samples and
centrifuge samples 41
6.1 Extraction and concentration step efficiencies 49
6.2 Comparison of the concentration of total suspended
matter (TSM) in the ambient water with that in the
centrifuge effluent.' Also shown are the concentra-
tions of total carbon in the suspended material, its
carbon:nitrogen ratio (C:N), and the chlorite:illite,
quartz:illite, and feldspar:illite ratios 53
6.3 Representative particle size distributions from
the Skagit and Fraser Rivers 55
6.4 The concentration of sediment-accommodated Prudhoe
Bay crude oil for various initial oil loadings 57
6.5 Accommodation of Prudhoe Bay crude oil on Fraser
River suspended sediments at 10°C and 32°/oo 64
7.1 Component listing and concentrations for aliphatic
standard (ALK-9) and arene standard (PAH-6) 71
7.2 Sampling protocol for suspended hydrocarbons at
each of the time series stations 74
7.3 Concentrations of saturated and unsaturated
hydrocarbons at stations sampled 77
7.4 Concentrations of normal alkanes and the isoprenoid
hydrocarbons pristane and phytane at stations occu-
pied during MESA-II 79
ix
-------
Number Page
7.5 Concentrations of normal alkanes and the isoprenoid
hydrocarbons pristane and phytane at stations
occupied during MESA-III .................. 84
7.6 Summary of hydrocarbon concentrations, organic
carbon, carbon: nitrogen ratios, and the ratio
of extractable hydrocarbons to organic carbon at
selected stations ...................... 89
8.1 Principal characteristics of the LANDSAT satellite
and multispectral scanner .................. 92
Appendix
A.I Seasonal distributions of selected hydrocarbons
at station 2 (48°11.3'N 122°48.6'W) ............. 134
A. 2 Seasonal distributions of selected hydrocarbons
at station 5 (48°14.0'N 123°17.2'W) ............. 135
A. 3 Seasonal distributions of selected hydrocarbons
at station 15 (48°24.2'N 122°41.0'W) ............ 136
A. 4 Seasonal distributions of selected hydrocarbons
at station 17 (48°50.6'N 122°46.2'W) ............ 137
A. 5 Seasonal distributions of selected hydrocarbons
at station 23 (48°55.0'N 123°6.5'W) ............ 138
A. 6 Seasonal distributions of selected hydrocarbons
at station 26 (49°2.0'N 123°15.5'W) ............ 139
A. 7 Seasonal distributions of selected hydrocarbons
at station 32 (48°34.3'N 123°13.5'W) ............ 140
-------
ABSTRACT
With the projected development of petroleum and natural gas reserves in
Alaska, the waters of northern Puget Sound and the Strait of Juan de Fuca
may become major transportation routes through which Alaskan petroleums are
delivered to Washington State refineries. Associated with increased produc-
tion of the refineries will be the exportation of refined products to markets
outside the State of Washington.
The seasonal distributions of total suspended solids were determined for
the area north of Admiralty Inlet, east of Port Angeles, and south of the
Fraser River between November 1976 and August 1977. Typical values ranged
from 0.5 to 2 mg/J, with the highest concentrations observed near the Fraser
River (8 mg/i) and Deception Pass (2-3 mg/£). Vertical distributions of sus-
pended particulate matter (SPM) showed highest values in the surface and
near bottom waters. High surface concentrations are believed to be due to
seasonal/temporal fresh water runoff and primary production; elevated levels
near the bottom are probably related to resuspension processes. Seasonal
variability was insignificant on a regional basis except for areas directly
influenced by river runoff. Diurnal variability was most pronounced near
major sediment sources and at stations characterized by large tidal excur-
sions.
In a complementary study, LANDSAT images were utilized to study surface
trajectories of sediment plumes originating from the Fraser and Skagit
Rivers. Major sediment plumes originating from the Fraser River can be
traced across the Strait of Georgia and through Porlier, Active, and Boundary
Passes. Trajectories during the ebb tide are southeast along the coast; but
during flood tide, the trajectory is west and northwest along the northern
coast of Galiano Island. Sediment plumes originating from the distributaries
of the Skagit River are most pronounced in early summer. At this time sus-
pended sediments from the Skagit River can be traced as far south as the
middle of Saratoga Passage and as far north as Deception Pass.
As a corollary to the suspended sediment distribution studies, the
composition and abundance of hydrocarbons associated with suspended matter
was evaluated at five strategic locations in the northern Puget Sound region.
Hydrocarbons extracted from suspended matter ranged from 0.2 mg/g to 1.4 mg/g
dry weight. Major identifiable paraffins were largely biogenic (e.g., penta-
decane, heptadecane, pristane, etc.), although one sample taken near the
Fraser Rtver may have been contaminated with motor oil. Similarly, samples
taken from the Strait of Juan de Fuca show the possible presence of
weathered petroleum residues (i.e., tar balls), which is not unexpected
given the level of transportation activity in this area. Within the limits
of these few data, we conclude that suspended matter in these waters is not
obviously contaminated with petroleum hydrocarbons, but low levels of con-
taminants may be present that were not identifiable because of the modicum
concentrations of suspended matter present.
XI
-------
Laboratory measurements also were performed under simulated natural
conditions to investigate the short-term interaction between Prudhoe Bay
crude oil and two locally-derived riverine sediments. These experiments
showed that significant concentrations of crude oil may be accommodated on
suspended matter under optimum conditions. Skagit River sediments, being
significantly coarser than suspended material from the Fraser River,
accommodated and settled up to 100% its weight in oil at 10°C (S = 32°/oo),
but only 40% at 15°C (S = 32°/oo). When smaller particles (Fraser River)
were subjected to the same experimental conditions, considerably less oil
was sedimented (up to 17%). However, much of the remaining oil and sediment
was present in a surface slick. Experiments show that significant amounts
of oil may be accommodated on suspended sediments, but the quantity retained
will depend on the isoelectric point of the oil and sediment particles,
particle size, temperature, and the concentration of oil relative to that of
sediments.
xi i
-------
1. INTRODUCTION
1.1 GENERAL STATEMENT
With the recent development of petroleum reserves at Prudhoe Bay and the
projected development of petroleum and natural gas reserves on the OCS of
Alaska, northern Puget Sound and the Strait of Juan de Fuca may become a
major transportation route through which Alaskan petroleums are delivered to
Washington State refineries or transshipped to northern tier states. Refin-
ing of petroleum is presently carried out at Cherry Point, Ferndale, and
Anacortes refineries. Associated with increased production of these refin-
eries will be the exportation of refined products (e.g., gasoline, diesel
fuel, lubricating oils, etc.) to markets outside the State of Washington. A
portion of the products undoubtedly will be transported by water, thus creat-
ing an increase potential for hydrocarbon loading of the local marine waters
through minor chronic spillage or a major tanker accident.
With few notable exceptions, the region has not been plagued with
massive oil spills, although the effects of chronic, low level inputs of
petroleum and refined products have not been adequately assessed. In the
past, much of the crude oil was delivered to Washington State refineries by
pipeline from Canada, but plans announced by the National Energy Board of
Canada will systematically Curtail and finally terminate all exports of
crude oil by 1982 (EPA, 1977). This alone will result in a significant in-
crease in tranker traffic to meet local domestic needs. This event will not
affect the marine shipment of refined products from the local refineries,
whose production schedules should increase with the availability of Alaskan
crude oil.
At the present time, the proven reserves of Prudhoe Bay are 9.6 billion
barrels with an additional estimated reserve of 3.2 billion barrels locked
up in other north slope reserves (EPA, 1977). By 1985, it is estimated that
approximately 3.1 million barrels per day will be produced from Alaska, the
bulk of it derived from the north slope via the trans-Alaskan pipeline (EPA,
1977). Numerous scenarios governing the allocation and transportation of
this crude oil to west coast ports and elsewhere are currently being debated.
While no firm estimates are available on the quantity of crude oil that will
be shipped to and/or through Washington State, it remains clear that ever
increasing amounts of petroleum will be moved through the Strait of Juan de
Fuca and- San Juan Passages via tankers to meet local demand.
Once petroleum hydrocarbons are introduced into the marine environment,
a combination of physical, chemical, and biological processes become opera-
tive in the destruction and removal of the oil. These processes include
spreading, dispersion, atmospheric injection, evaporation, chemical and bio-
chemical oxidation, emulsification, and the physical sedimentation of oil on
particles (NAS, 1975). While all of these processes are of special interest,
this study addresses the temporal and spatial distributions of suspended
-------
particulate matter and its adsorption characteristics relative to a typical
Alaskan crude oil.
1.2 OBJECTIVES
Oil spilled onto the surface of the ocean is acted upon by several
physical processes, including solution, emulsification, attachment to sus-
pended particles, evaporation, and aerosol formation. The latter two pro-
cesses represent a physical transfer of oil from the aquatic environment,
thus reducing its potential impact on marine organisms. In contrast,
petroleum in true solution, emulsified or sorbed to sediments represents
a direct impact on marine organisms.
Of the water accommodated fraction, oil sorbed to particles represents
a potential impact of longer duration than either oil in true solution or
emulsified. Most of the components of oil are sparingly soluble in natural
waters (McAuliffe, 1977), the exceptions being the low molecular weight aro-
matics. Thus, their impact is minimal both in terms of concentration and
duration. Likewise, oil-in-water emulsion is thermodynamically unstable in
sea water (Huang and Elliott, 1977), thus oil droplets would tend to
coalesce into a surface slick when the turbulent energy is diminished.
On the other hand, oil agglutinated to particles is stabilized by the
association (Huang and Elliott, 1977) and results in wide dispersal of oiled
particles that may impact a range of planktonic and benthic organisms. Re-
cent studies of oil spills in coastal regions containing high suspended
matter concentrations clearly have indicated rapid dispersal of the oil by
adsorption onto particles (Forrester, 1971; Farrington and Quinn, 1973).
However, other investigators have observed surface oil slicks coexisting
with suspended matter plumes (Kolpack, 1971). Apparently, the dispersal of
oil does not always result from a simplistic model of adsorption and trans-
port in association with suspended particles.
The major objectives of this multidisciplinary study are directed
toward a better understanding of the importance of suspended matter in the
transport of crude oil. Recognizing the importance of suspended matter in
the transport and dispersal of sorbed hydrocarbons, an element of this
study addresses the distributions, mineralogical compositions, and trajec-
tories of marine and riverine suspended matter in the waters of "northern
Puget Sound." Synoptic trajectories and distributions were evaluated
photographically using LANDSAT imagery, augmented with sea truth measure-
ments taken seasonally.
In concert with these activities, the oil loading capacity of both
Fraser and Skagit River sediments was studied under simulated environmental
conditions. Prudhoe Bay crude oil was used as the adsorbed phase.
The third major thrust of the study deals with natural hydrocarbon-
particulate matter associations. Because the Strait of Juan de Fuca,
San Juan passages, and the southern Strait of Georgia (referred to here as
northern Puget Sound) represent major transportation waterways to British
-------
Columbia and the State of Washington, the compositions and ambient concentra-
tions of sorbed hydrocarbons on suspended solids were investigated.
In a related study, the seasonal distributions of the dissolved low
molecular weight aliphatic hydrocarbons (LMWH) were determined in order to
quantify the baseline levels of these components and to make a preliminary
assessment of the current levels of petroleum input into these waters.
Because this subprogram is not directly related to the question of suspended
matter transport of petroleum, it was included in Appendix A.
For clarity, the results of this research are described in four separate
sections (Chapters 5-8). The first section discusses the seasonal and diurnal
distributions of suspended matter. This discussion is followed by a prelimi-
nary treatment of the absorptive behavior of river-derived sediments toward
Prudhoe Bay crude oil. The third section discusses and evaluates the current
levels of sorbed hydrocarbons and their probable sources. Lastly, a synoptic
overview of the surface suspended sediment distributions and probable trajec-
tories of riverine material are provided as a focus for probable areas of
impact. The purpose of the study and research objectives are outlined in
Chapter 1, followed by a summary of conclusions and recommended research
activities in Chapters 3 and 4. For the purpose of continuity, the geographi-
cal and hydrological setting of the Strait of Juan de Fuca, San Juan passages,
and the lower Strait of Georgia are reserved for Chapter 2.
-------
2. GEOGRAPHY, PHYSICAL OCEANOGRAPHY, AND HYDROLOGY
2.1 PHYSIOGRAPHIC SETTING
Figure 2.1 shows the physical setting of the study region. The area is
an inland sea with access to the open Pacific Ocean through two major water-
ways, the Strait of Georgia and the Strait of Juan de Fuca. The Strait of
Georgia, to the north, is one of the largest inland waterways on the west
coast of North America. It is partially enclosed with Vancouver Island form-
ing the western boundary and the mainland of British Columbia and northwestern
Washington forming the eastern boundary. The Strait of Georgia is about
220 km long, 33 km wide, and has an average depth of about 150 m. The San
Juan Archipelago and the Canadian Gulf Islands separate the Strait of Georgia
from the Strait of Juan de Fuca. Passage between these major waterways is
primarily accomplished through Haro Strait to the west and Rosario Strait to
the east.
The Strait of Juan de Fuca, to the south, is a submarine valley extending
from the Pacific Ocean to Whidbey Island and Rosario Strait, about 145 km
long. The width varies between 20 and 24 km from the entrance to the Port
Angeles area, where it narrows to 16 km near Victoria, B.C., before widening
to about 40 km. The Strait contains two basins which are separated by a
cross-channel ridge or sill. The ridge extends southward from Victoria, at
an approximate depth of 60 m. The western basin or Outer Strait slopes
gradually in a seaward direction. The eastern basin or Inner Strait contains
several channels which lead into Haro Strait, Rosario Strait, and Admiralty
Inlet.
2.2 CIRCULATION PATTERNS AND HYDROGRAPHY
Circulation patterns and hydrography for the study region have been
studied and reviewed by several authors (Tully, 1942; Waldichuk, 1957;
Herlinveaux and Tully, 1961; Chang et al., 1976; Parker, 1977; Schumacher et
al., 1978), and only a brief summary is deemed necessary for the purpose of
this report.
The primary factors that control circulation and the distribution of
properties in the study region include tides, fresh water, runoff, winds and
atmospheric pressure variations, with secondary influences due to coriolis
force, centrifugal force, and topography. The Strait of Georgia is charac-
terized by a strong vertical stratification which results from fresh water
input from numerous mainland rivers, the Fraser River being the most important.
Driven by estuarine flow, the brackish water moves progressively seaward, pri-
marily through the San Juan passages into the Strait of Juan de Fuca, where
mixing occurs as a result of turbulent tidal energy. As the brackish water
mixes with the saline Pacific Ocean water, part of it is returned to the
deeper waters of the Strait of Georgia. However, the major portion escapes
to the Pacific Ocean in the upper layer. Salt balance 1s maintained by the
intrusion of colder, more saline water from the Pacific at mid-depths 1n the
Strait of Juan de Fuca during the summer months (Waldichuk, 1957). This water
-------
I23e00'
122° 40'
122" 20' o
CANADA
UNITED STATES
23^20' I23'OO'
122° 20'
Figure 2.1 Physical setting of the study region
-------
moves eastward through the strait, then northward through the San Juan
passages, where it mixes with the less saline water of the Strait of Georgia.
Throughout most of the region the density structure of the water column
is dominated by variations in salinity rather than in temperature. For exam-
ple, during the summer months, the thermocline coincides with the halocline
in the Strait of Juan de Fuca. However, in winter the waters are nearly iso-
thermal and the stability is directly dependent upon the salinity structure.
In the Strait of Georgia, tides and winds are the major controlling factors
for mixing of surface waters, particularly in winter when nearly homogenous
conditions prevail.
The influence of winds on surface circulation appears to be seasonally
dependent. During the winter months the Aleutian Low determines the prevail-
ing wind pattern for the Pacific Northwest, including British Columbia and
Washington. The prevailing winds are predominantly from the southeast. In
the Strait of Georgia the southeasterly winds set up a counterclockwise wind
pattern over the area, providing energy to the surface waters and adding to
the general counterclockwise circulation pattern. In the Strait of Juan de
Fuca, west of Port Angeles, the orographic effect of the Olympic Mountains
turns these winds seaward along the Strait. Wind speeds in this region aver-
age just over 20 knots. The surface waters respond to the wind forcing by
absorbing energy from the winds and increasing surface currents in the gen-
eral direction of the winds.
During the summer the North Pacific High predominates and the winds are
primarily from the northwest. These winds are less intense and more vari-
able; and, consequently, their effect on circulation of surface waters in the
study area is less pronounced than in winter.
2.3 RIVER RUNOFF AND SEDIMENT DISCHARGE
Table 2.1 shows runoff data for the major rivers that discharge into
the study region. The data show that of the total annual runoff, which is
about 116 x 109m3, greater than 90% is derived from two rivers, the Fraser
River and the Skagit River.
The Fraser River drains an area of approximately 207,000 km2, which
consists of most of the Interior Plateau of British Columbia between the
Coast Mountains and the Rocky Mountains. The elevated nature of the Interior
Plateau determines the main feature of the discharge pattern which is the
spring floods derived from melting snow. Figures 2.2a and 2.2b show the
range, mean, and standard deviation of the water and sediment discharge at
Hope, B.C., for the period between 1967 and 1976 (Water Survey of Canada,
1967-1976). The annual mean flow is 2960 cubic meters per second and the
total annual sediment discharge is approximately 18 million metric tons
(Table 2.2). The maximum discharge of water and suspended sediments occurs
during the months of April through August.
-------
TABLE 2.1 Average annual runoff from the major rivers discharging
into the study region
Area of Drainage Average Annual Runoff
River Basin (km2) (m3 x 109)
Fraser*
Skagit**
Nooksack**
Stillaguamish**
207,000
8,040
3,270
1,790
93.4
14.2
4.6
3.6
*Water Survey of Canada, Water Data, Canadian Rivers, Inland Waters
Directorate, Ottawa, Canada, 1967-1976.
**Pacific Northwest River Basins Commission. Puget Sound Task Force.
Comprehensive Study of Water and Related Land Resources, Puget Sound
and Adjacent Waters, State of Washington, Appendix III, Hydrology
and Natural Environment, March 1970.
-------
o 12,000
UJ
~ 10,000
Or
i 8,000
0
tr>
a: 6,000
4,000
2,000
- FRASER RIVER AT HOPE
a
Q- MONTHLY RANGE (1967-1977)
77(- MONTHLY STANDARD OEVIATIONII967-I977)
• - MONTHLY MEAN (1967.1976)
O MONTHLY MEAN (1977)
JAN
FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
500
UJO 400
(S —
K. X
< V
OQ
v.
5«j 300
tl
*2
St200
tos
IOO
FRASER RIVER AT HOPE
Q- MONTHLY RANGE (1967-1977)
Q-MONTHLY STANDARDOCVIATIONII967-I977)
A - MONTHLY MEAN (1967.1976)
A- MONTHLY MEAN (1977)
^
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Figure 2.2 Monthly range, mean, and standard deviation of: a. water dis-
charge and b. suspended sediment discharge for the Fraser River
at Hope, B.C. for the period from Jan. 1967 through Sept. 1977
(Water Survey of Canada, Sediment Data, Canadian Rivers, Inland
Waters Directorate, Ottawa, Canada, 1967-1976).
8
-------
TABLE 2.2 Comparison of water and sediment discharge for the Fraser and Skagit Rivers
during period of record (1967-1976)
Discharge
Year
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967
Mean
Std. Dev.
Fraser
River Discharge
(m3/sec)
3674
2649
3172
2492
3398
2832
2166
2753
3313
3172
2962
462
River**
Sediment Discharge
(metric tons/day)
86560
32683
63428
44043
79424
44544
32846
36032
64362
64139
63581
27983
Skagit
River Discharge
(m3/sec)
497
561
596
379
625
551
379
414
583
464
505
92
River***
Sediment Discharge
(metric tons/day)
2429*
2184
3075
-
-
-
-
-
-
-
2563
460
*January thru October.
**Water Survey of Canada (1967-1976).
***Water Resources Data for Washington, 1976.
-------
At Hope, the Fraser River emerges from the Coast Mountains and flows
through an alluvial valley to the Strait of Georgia. Near New Westminister
(see Fig. 2.1), the Fraser bifurcates into a major channel or the Main Arm,
which accounts for approximately 90% of the flow, and a minor channel,
known as North Arm, which branches off at Marpole forming Middle Arm. Main
Arm discharges into the Strait of Georgia at Stevenston and North Arm enters
the Strait at Point Grey.
The Skagit River and its tributaries drain an area of approximately
8,040 km2. The major tributaries of the Skagit River are the Baker, Cascade,
and Sauk Rivers. The headwaters of the Skagit River and its tributaries are
located in the North Cascade Range, where flow is partially derived from
melting snow. Near Marblemount, Washington, the Skagit River is joined by
the Cascade River, where it flows through broad flood plains and lowland
areas until it reaches the coast. At a location about 12 km from the coast,
the river splits into three distributaries which flow into Skagit Bay.
Figure 2.3 shows water and sediment discharge data for the Skagit River at
Mt. Vernon, Washington for 1975.* The data show a bimodal distribution for
both water and suspended sediments. The major peaks occur in two periods:
October through December and May through July. The October-December peak is
associated with excessive rainfall in the lowland areas. The May-July peak
corresponds with spring runoff due to melting snow near the headwaters.
*While water discharge records for the Skagit River are fairly complete
from 1930 to the present, very few records for suspended sediments are avail-
able. Therefore, the records for 1975 were used to show the salient features
of the Skagit River discharge pattern.
10
-------
1400
Z 1200
ui
•o
— 1000
o
oc
800
u
z
o
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
PERIOD OF RECORD (1975)
Figure 2.3 Monthly mean discharge of water and suspended sediments
of the Skagit River at Mt. Vernon during 1975 (Water
Resources Data for Washington, 1976).
11
-------
3. CONCLUSIONS
3.1 SUSPENDED MATTER DISTRIBUTIONS
Typical values of the concentration of total suspended solids in the
waters of the study area between November 1976 and August 1977 were 0.5-
2 mg/£. Significant local modification of this concentration level in
surface waters occurred north of the San Juan Archipelago, within the
influence of the Fraser River plume, where concentrations were as high as
8 mg/£, and immediately seaward of Deception Pass, where concentrations were
2-3 mg/£. Concentration values in the mid-depth and bottom waters showed
little influence from riverine sediment sources.
The typical vertical distribution of SPM throughout the area tended
towards relatively high values in the surface and bottom waters and relatively
lower values in the mid-depth regions. This distribution is presumably due to
different agents of particle production in different layers of the water col-
umn: high phytoplankton growth and fresh water runoff in the surface waters,
and substantial additions of resuspended bottom sediment into the bottom
waters.
Temporal variability of the SPM distributions was examined both on a
seasonal and diurnal basis. Seasonal variability over most of the region,
except for those areas directly influenced by river runoff, was negligible;
overall SPM concentrations were 1.8 ± 2.4 mg/A for MESA I, 1.4 ± 0.8 mg/fc
for MESA II, and 1.2 ± 1.0 mg/i for MESA III. The somewhat higher mean value
and standard deviation for MESA I is the result of very high SPM values near
the Fraser River and Deception Pass during November 1977.
Diurnal variability was most pronounced at locations where strong tidal
currents and/or major sediment sources (Fraser River, Deception Pass) were
present. At other locations the vertical SPM distribution was relatively
uniform over short time scales.
3.2 SUSPENDED HYDROCARBONS
A systematic survey of suspended hydrocarbons was initiated in the
waters of the eastern Strait of Juan de Fuca, San Juan Island Passages, and
the southern Strait of Georgia. A total of five locations were selected for
detailed study. Hydrocarbons extracted from suspended matter ranged from
0.2 mg/g dry weight to 1.4 mg/g dry weight. The range was largely due to
variations in biological hydrocarbons and no correlations were apparent with
probable sources of petroleum hydrocarbons (i.e., Fraser River). Both the
amounts of hydrocarbons extracted and their compositional character suggest
minimal impact with petroleum hydrocarbons, although weathered petroleum resi-
dues in a few samples may have been present. One exception was a sample
taken near the Fraser River 1n which heavy motor oil components may have been
present. Within the limits of these few data and the small sample weight of
material, we conclude that suspended matter in the northern waters of Puget
Sound is not obviously contaminated with petroleum hydrocarbons, but
12
-------
incipient levels may be present. More extensive analysis of larger samples,
with attention to specific marker compounds, is required.
3.3 OIL-SEDIMENT INTERACTION STUDIES
Laboratory experiments were performed under simulated natural conditions
to investigate the short-term interaction between Prudhoe Bay crude oil and
two locally-derived riverine sediments. Suspended sediment obtained from the
Fraser and Skagit Rivers was mixed with varying quantities of crude oil in
sea water at 10°C and 15°C. Cursory attention was given to the influence of
dissolved organic carbon in the interaction.
These experiments showed that significant concentrations of crude oil
may be accommodated on suspended matter under optimal conditions. The mean
particle size of Skagit River sediments was somewhat larger than the material
collected from the Fraser River and accommodated up to 100% of its weight in
oil at 10°C. An extrapolated value at the same loading (T = 15°C) would have
been less than 40%. When smaller particles (Fraser River) were subjected to
the same experimental conditions, considerably less oil was sedimented (up to
17%), but much of the clay fraction was retained in a surface slick. If
weathering of the oil had been allowed to occur, the surface oil and sediment
particles would have reached sufficient density to overcome surface tension
and buoyancy and subsequently settled.
Our preliminary conclusions are that when coarse-grained material (i.e.,
silt) is added to oil, the oil coats the particles and settles rapidly. If
the particles are finer (i.e., clay), the oil appears to inhibit normal floc-
culation of the clay-size material and the sediment is retained in a surface
oil layer. Experiments show that significant concentrations of oil may be
accommodated in suspended sediments, but the quantity retained in such a
fashion will depend on the isoelectric point of the oil and sediment parti-
cles, particle size, temperature, and the concentration of oil relative to
that of the sediment. Kinetic factors are also important if the oil and
sediment are both present in low abundance.
3.4 LANDSAT IMAGERY
A set of LANDSAT images, obtained during the period between 1972 and
1977, have been utilized to study the surface trajectories of sediment
plumes originating from the Fraser and Skagit Rivers. These plumes are
natural tracers of the flow patterns of river water that are discharged
into northern Puget Sound from these rivers.
Three separate plumes can be observed emanating from the mouths of the
distributaries of the Fraser River. The plumes from Main Arm and Middle
Arm join together to form a well-defined jet which can be traced across the
Strait of Georgia and through Porller, Active, and Boundary Passes. During
ebb tide the plume is directed to the southeast from a point about midway
between Steveston and Porlier Pass. The flood tide drives the plume across
the Strait and to the northwest along the northern coast of Galiano Island.
13
-------
The plum from North Arm moves to the northwest past Point Grey where it
bifurcates, with some material flowing to the northwest during ebb tide and
the remaining material moving into Burrard Inlet.
The existence of a number of separate plumes in some of the images
suggests that the plumes are probably capable of maintaining their identity
for periods longer than a single cycle. This implies that a dynamic balance
exists between the inertial and pressure forces associated with the plumes
and the coriolis and tidal forces associated with circulation patterns in
the Strait.
The plumes from the distributaries of the Skagit River are most pro-
nounced in early summer, during the peak runoff. During this period sus-
pended sediments from the Skagit River can be traced as far south as the
middle of Saratoga Passage and as far north as Deception Pass. During ebb
tide, suspended solids from the Skagit River flow into Rosario Strait.
During the period of low discharge, the Skagit River plume is confined to
the nearshore regions of Skagit Bay.
14
-------
4. RECOMMENDATIONS
4.1 SUSPENDED MATTER DISTRIBUTIONS
Results of this investigation describe the typical concentration of
total suspended particulate matter to be expected during various seasons
within the study area. Areas of high vertical and horizontal gradients in
suspended matter also have been delineated. In addition, a few measurements
at selected stations have indicated the magnitude of diurnal variability to
be expected in the suspended matter distributions.
A logical extension of this work, although not proposed under this
study, is to proceed with a detailed investigation of sediment transport
processes. Given the likelihood that pollutants such as oil will be
associated with the suspended matter, knowledge of the transport paths of
the sediment, its residence time, and final depositional sites would be of
immense value in assessing possible impacts. Such a study should include
optical measuring devices (nephelometers or transmissometers) together with
continuous recording current meters. Emphasis should be placed on the near-
surface and near-bottom waters.
Our studies have shown that particle composition and size are critical
parameters in assessing the adsorptive characteristics of suspended matter.
Future studies should emphasize the sources of these sediments, including
biological, fluvial, and resuspended bottom material. Detailed mineralogies
of the detrital terrigenous fraction and particle size would be most useful
in assessing its adsorptive behavior toward crude oil.
4.2 CHARACTERIZATION OF SUSPENDED HYDROCARBONS
The preliminary studies conducted in the eastern Strait of Juan de Fuca,
San Juan Island passages, and the southern Strait of Georgia have suggested
the presence of petroleum hydrocarbons, although the source of these hydro-
carbons was not unequivocal. Small amounts of suspended matter (< 1 g to
5 g dry weight) severely hampered detailed analysis of the hydrocarbon frac-
tions, in particular the aromatic compounds which are ubiquitous in petro-
leum and refined products. New procedures should be implemented in future
work by which larger amounts of suspended matter (10-20 g) may be recovered
for detailed HC analysis.
These studies also pointed to the inadequacies of the present analytical
procedures used to distinguish petroleum-related hydrocarbons from the ever-
present biological components. More intensive laboratory efforts are re-
quired to identify petroleum marker compounds that are persistent and can be
readily assayed. Because petroleum may impact organisms via several path-
ways, suitable Identification procedures should be developed for biota, sus-
pended sediments, bottom sediments, and water.
15
-------
4.3 OIL-SEDIMENT INTERACTION STUDIES
The studies performed in the work were preliminary in scope and served
to identify major factors relating to the accommodation of oil by locally-
derived riverine sediments. These investigations have shown the importance
of surface chemistry in the adsorption process as well as the effect of par-
ticle size, mineralogy, associated organics, and temperature. All of these
factors, to a greater or lesser degree, play an important role in governing
the surface interaction between suspended oil and particles. Without a bet-
ter understanding of the physical-chemical nature of interface reactions
involving natural particles and oil, predictive behavior of the system will
be left to a never-ending series of empirical experiments.
We recommend that specific studies be implemented by which the miner-
alogy and surface coating of particles are examined in terms of their
interactions with oil droplets. Emphasis should be placed on the impor-
tance of surfactants, either in the oil or in the associated organic
matter, and their importance toward interfacial reactions. The formation
of colloidal electrolytes needs to be examined as a possible mechanism for
oil accommodation as well as other interaction involving complex organics
that may be present in oil or in suspended matter. Effects of salt (ionic
medium) and temperature are easily incorporated once the fundamental mech-
animsm describing the adsorption process is understood.
4.4 LANDSAT STUDIES
Results of the present study indicate that the LANDSAT images are
extremely useful for studying surface trajectories of sediment plumes origi-
nating from the Fraser and Skagit Rivers. These data allow for synoptic
observations of variations in plume trajectories which can be related to
differences in tidal stages. In future studies of this kind, LANDSAT obser-
vations should be correlated with corresponding sea-truth data. If the re-
sulting correlations are consistent in space and time, the data may be used
to develop suspended matter distribution maps based upon the LANDSAT data.
The reconstructed distribution maps may then be compared with historical
records of river discharge to provide a realistic picture of the relationship
between annual and seasonal variations of river discharge and suspended mat-
ter distributions.
16
-------
5. SUSPENDED MATTER DISTRIBUTIONS
5.1 STATION LOCATIONS AND SAMPLING RATIONALE
The study area of this project included the eastern portion of the
Strait of Juan de Fuca, the San Juan passages, and the southern Strait of
Georgia. Thirty-five station locations (Fig. 5.1) were designated for
seasonal sampling coverage on three cruises: MESA I (Nov. 16-24, 1976),
MESA II (March 10-16, 1977), and MESA III (Aug. 7-14, 1977). These times
were chosen on the basis of the local climate and runoff pattern. The domi-
nant runoff source in this area is the Fraser River, whose flow peaks
sharply between early May and late July (Fig. 2.2). The November and March
cruises thus sampled the area during the relatively low runoff autumn and
spring periods, while the August cruise occurred immediately after the mid-
summer runoff peak.
The station locations were chosen to form transects across the major
passages of the survey region where horizontal and vertical gradients of the
distribution of suspended particulate matter (SPM) were expected to be the
greatest. Admiralty Inlet, the principal passage into Puget Sound, was cov-
ered by stations 1-3. Two transects across the Strait of Juan de Fuca,
stations 4-7 and 8-10, covered the area between the inland waters and the
entrance to the Pacific Ocean. SPM distributions around the San Juan Archi-
pelago were measured across two east-west transects north (stations 17-21)
and south (stations 11-15) of the islands. Stations were also occupied
within Haro and Rosario Straits. Three transects, stations 21-30, monitored
the Fraser River plume.
Since a synoptic survey of such a large region is impossible, the
possible effects of tides on the temporal variability of SPM were investi-
gated in a series of 24-hr time series stations (Fig. 5.1). SPM measure-
ments were repeated approximately every two hours at these stations. The
locations of these stations were chosen to represent a wide range of tidal
current velocities, to represent a variety of SPM sources (oceanic, riverine,
etc.), to provide wide spatial coverage, and to be compatible with the sus-
pended matter-hydrocarbon sampling program (Section 6).
Coverage of this sampling grid was never complete during any of the
cruises. Poor weather conditions occasionally aborted stations or shortened
time series measurements on each cruise, particularly in the Strait of Juan
de Fuca. International clearance problems forced cancellation of all sta-
tions in the Canadian portion of the Strait of Georgia during MESA II.
Technical problems with the CTD and nephelometer systems caused some inter-
mittent loss of data. Nevertheless, the data base is extensive and so the
gaps are not generally serious. Because of the large amount of data, de-
tailed discussions 1n this report will be limited to the transects formed
by the following stations: 4-7 (Transect A), 11-15 (Transect B), 17-21
(Transect C), and 24-27 (Transect D). These transects are representative of
the entire area and include (or are adjacent to) the four principal time-
series stations (9, 15, 17, and 26).
17
-------
123*40'
123*20'
123*00'
122*40'
122*20' ;
123
Figure 5.1. Station locations for MESA I, II, and III. Light scattering
measurements were made at all stations. Circles indicate
stations where water samples also were collected. Squares
indicate where time-series measurements were made and where
large volume suspended particulate matter samples were col-
lected by centrifuge.
18
-------
5.2 OBSERVATIONAL PROCEDURES
The distribution of SPM within the study area was determined by
continuous vertical profiles of light scattering intensity (nephelometer
profiles) at each station. The nephelometer (Sternberg et al., 1974) con-
sists of a flashing xenon light source, a scattered light detection system,
a data transmission system, and Ni-Cd batteries mounted in a self-contained,
easily portable, deep sea housing. During MESA I and MESA III, the nephelom-
eter was interfaced with a Plessey 9400 CTD and a real-time surface-to-
bottom profile of light scattering intensity was produced. Technical
problems on MESA II required the use of the nephelometer's internal strip
chart recorder.
Discrete water samples were collected at six (or less) depths at
approximately half the stations (Fig. 5.1) by means of 6-liter PVC sampling
bottles. Aliquots from each sample were vacuum filtered through a 47 mm
diameter, 0.4 ym pore size Nuclepore polycarbonate filter. Filters were
rinsed with three 10 ml aliquots of distilled, deionized, membrane filtered
water, placed in individual plastic petri dishes, desiccated, sealed, and
returned to the laboratory. The absolute concentrations of SPM obtained
from gravimetric analysis of these samples were compared to the nephelometer
measurements in an attempt to calibrate the relative nephelometer values in
terms of SPM concentration. Unfortunately, the correlation between nephe-
lometer values and absolute SPM concentration at the same station was poor
(Fig. 5.2). Because no rosette sampling system was available, nephelometer/
CTD casts and bottle casts were performed on successive lowerings rather than
simultaneously. Consequently, the actual depth of each water sample could
only be estimated from the meter wheel and wire angle. In a dynamic and
patchy estuarine environment, with steep horizontal and vertical SPM gradients,
it proved impossible to sample the same water parcel with both nephelometer
and sampling bottle with the available sampling procedures. Even if the
sampling procedure was ideal, optical measures of SPM concentrations would be
difficult due to the particle inhomogeneities in the study area (i.e., high
phytoplankton concentrations in the surface waters, largely inorganic parti-
cles at depth). Although scattering intensity depends to a large degree on
the concentration of material in the water, it is also affected by changes
in the particle size distribution, the index of refraction, and the particle
morphology.
As an example of the utility of nephelometer profiles in a program of
this type, Figure 5.3 illustrates the accuracy of calibration which may be
achieved if water samples can be collected simultaneously with the light
scattering readings. Thus, although absolute determination of the SPM con-
centration from the nephelometer data in the present study is difficult,
the nephelometer profiles are nevertheless very useful and informative.
Rather than yielding instantaneous values of the SPM concentrations of a
particular water parcel, they reveal the gradients and overall magnitude of
SPM throughout the entire water column. As discussed below, the transects
of nephelometer values are internally consistent and the gradients often
parallel gradients in the temperature distribution. Typical values for the
absolute concentration of SPM are given by the water samples, and the details
of the gradients are furnished by the nephelometer profiles.
19
-------
4'
I
s.
t
a
kl
J I
i
§'
i
a
°<
i.n MO ue
• *
*
* •
• * • •
• • 9
•• ••• ."• ' *
'"vA ?;":.'.:
• • MESA 1
4'
9'
t-
"
^
*
a
.
a *
• *
Q ft
" »
» °
V '"'* . * '
o
MESA 2
4-
S-
2-
"
o<
•.<• T*
• *
*
1
• •
t * .
».* . '
• « • . •
* * I I *
0 •*•... • •
• •
0 • «| • *
.* * MESA 3
LIOHT SOATTERINB INTENSITY
Figure 5.2. Scatter plot of nephelometer data versus particulate concentration in the study
area. Reasons for the poor correlation are discussed in the text. Compare
these plots with Figure 5.3.
-------
ro
23456789 10
LIGHT SCATTERING INTENSITY
12 13
Figure 5.3.
Scatter plot of nephelometer data versus particulate concentration for some
Gulf of Mexico samples collected simultaneously with the light scattering
measurements. This calibration curve is an example and cannot be directly
used to interpret the present data.
-------
Water samples were also used to obtain samples for x-ray diffraction
mineralogy. The stations and depths of samples examined for mineralogy are
given in Table 5.1. In order to obtain enough material, samples often had to
be combined. In the laboratory, selected filters were treated with 15% H202
to remove the oxidizable organic matter, and the remaining inorganic sediment
load was removed from the Nuclepore filter ultrasonically. Oriented mounts
for x-ray diffraction analysis were prepared by filtering the resuspended
particles through silver membrane filters (0.45 ym mean pore size). Since
the SPM collected on the filters included silt-size particles as well as
clay-size, quantitative estimates of mineral abundances could not be deter-
mined. Instead, relative ratios of chloriterillite, quartz:illite, and
feldsparrillite were computed as indicators of these minerals' distribution
patterns. Montmorillonite was present only in trace amounts and kaolinite
was not detected.
A few samples were collected for particle size analysis in conjunction
with the in-situ pump sampling for suspended hydrocarbons.
5.3 RESULTS AND DISCUSSION
5.3.1 Suspended Particulate Matter Concentrations - Area! Distributions
5.3.1.1 Seasonal surface values. SPM concentrations as measured by
bottle sampling were relatively uniform throughout the year in the eastern
Strait of Juan de Fuca and the San Juan passages, varying between 0.5 and
2 mg/i (Figs. 5.4a, 5.5a, 5.6a). The influence of the Fraser River plume is
obvious in the Strait of Georgia, with concentrations as great as 8 mg/fc near
the river mouth in November and August. Although areal sampling was restricted
in March, samples taken as far north as the Canadian border yielded concentra-
tions of < 1 mg/£ (compared with > 3 mg/& in November and August). These low
concentrations correspond to the very low spring runoff typical of the Fraser
River (Fig. 2.2).
5.3.1.2 Seasonal near-bottom values. Figures 5.4b, 5.5b, and 5.6b show
the distribution of SPM values 5 m above the seabed. These values tend to pos-
sess somewhat more variability than the surface values because their actual
depth below the sea surface varies widely and resuspension of bottom sediments
may be an important process in controlling the observed concentration values.
The absolute value of near-bottom SPM concentrations throughout the
entire region is between 0.5 and 3 mg/fc - almost identical to the surface
values. Furthermore, there is no Fraser River influence detectable in the
bottom waters of the Strait of Georgia at any time of year.
5.3.2 Suspended Particulate Matter Distribution -
Seasonal Nephelometer Transects
The locations of the four representative nephelometer transects to be
discussed in detail in this report are shown in Figure 5.1. The sea bottom
profile for a particular cross-section sometimes changes slightly from
cruise to cruise due to small errors in reoccupylng a particular station.
22
-------
ro
CO
I23*W
I23*2O'
122*20
IZ3*<)0'
123*20'
122*40
Figure 5.4.
Concentration contours (mg/1) of particulate matter for surface and near bottom
samples from MESA I. Note that the Fraser River plume has a strong influence
only in the surface layer.
-------
ro
Figure 5.5. Concentration contours (mg/1) of particulate matter for surface and near bottom
samples from MESA II. Note the low spring-time values near both the Fraser
River and Deception Pass (at the north end of Whidbey Island).
-------
INJ
en
IZZ'ZQf
Figure 5.6 Concentration contours (mg/1) of particulate matter for surface and near bottom
samples from MESA III. Note the prominence of the Fraser River plume due to
the summer runoff.
-------
Cross-sections of the temperature distribution are also presented for
these transects in order to compare the SPM distributions with the hydrog-
raphy. Because of difficulties with the magnetic tape recorder on the CTD
system, density and salinity values were not available for all three
cruises.
5.3.2.1 Transect A (sta. 4-7). Scattering contours in these cross-
sections (Fig. 5.7) show very weak horizontal gradients except for an
apparent discontinuity below 40 m at the south end of the transect during
the August cruise. Scattering contours during March showed lower scattering
and weaker gradients than either November or August. In general, inferred
SPM concentrations in the deep water on the south side of the Strait of Juan
de Fuca (sta. 5) were less than in the shallower water on the north side.
This generalization agrees with the observation of Herlinveaux and Tully
(1961) that inward transport of (presumably less turbid) oceanic water domi-
nates on the south side, while seaward transport of Puget Sound and Strait
of Georgia water dominates on the north side.
The temperature cross-sections (Fig. 5.8) possess far more variability
than the nephelometer profiles. There was a distinct front across the
middle of the Strait in November, with warmer water on the southern side of
the Strait. In March, when the scattering gradients were lowest, the water
column was nearly isothermal. The strongest vertical gradients were, of
course, found in August. The vertical scattering gradients were also strong-
est at this time.
5.3.2.2 Transect B (sta. 11-15). This cross-section south of the
San Juan Archipelago reveals the influence of the Deception Pass SPM source
during all three seasons (Fig. 5.9), although the extent of its influence
was markedly reduced during the March cruise (see also Figs. 5.5, 8.2, and
8.3). The typical mid-depth scattering minimum was less well developed
south of Rosario Strait than south of Haro Strait, apparently because of the
Deception Pass SPM supply.
The temperature cross-sections (Fig. 5.10) agree particularly well with
the nephelometer profiles. During November, slightly warmer Deception Pass
water occupied the upper 40 m of the eastern half of the cross-section,
corresponding to the location of high scattering levels. Gradients were
much weaker in March, but a temperature front still separated the eastern
and western halves of the cross-section. Horizontal gradients in tempera-
ture and light scattering were superseded by the vertical structure in
August.
5.3.2.3 Transect C (sta. 17-21). SPM distributions along Transect C
(Fig. 5.11) north of the San Juan Archipelago were rather stable except for
the shallow water off Cherry Point. During November and August there was a
well-developed, although thin, mid-depth minimum off Cherry Point which may
or may not have been continuous with the broader minimum found further off-
shore. Below this minimum, scattering values increased steadily with depth.
During November, the scattering structure off Cherry Point was probably
closely related to the salinity structure, since a prominent halocline was
26
-------
MESA 1 TRANSECT A
.ST». 4 56
ro
MESA 2 TRANSECT A
,STA. 456
MESA 3 TRANSECT A
STA. 45 6
Figure 5.7. Light scattering values, Transect A. Cross-hatching at a station location
indicates the depth of daylight interference with the nephelometer. Verti-
cal exaggeration = 250x.
-------
MESA 1 TRANSECT A
.8TA. 456
MESA 2 TRANSECT A
,STA. 456
MESA 3 TRANSECT A
STA. 45 6
ro
to
120 -
Figure 5.8. Temperature values (°C), Transect A. Contour Interval is 0.1°C for MESA I and II,
1°C for MESA III. Vertical exaggeration = 250x. Note the nearly isothermal
structure during MESA II.
-------
MESA t TRANSECT B
,«T». .11 e
ro
MESA 2 TRANSECT B
.*r«, H a
MESA 3 TRANSECT B
IT*. II
Figure 5.9. Light scattering values, Transect B. Cross-hatching at a station location
indicates the depth of daylight interference with the nephelometer. Vertical
exaggeration = 250x. This transect is a good example of the mid-depth light
scattering minimum found throughout most of the study area.
-------
MESA I TRANSECT B
tn._ ii a
MESA 2 TRANSECT B
Jl B
MESA 3 TRANSECT B
IT*. ii a
Figure 5.10. Temperature values (°C), Transect B. Contour Interval is 0.1°C for MESA I
and II, 1°C for MESA III, Vertical exaggeration = 250x.
-------
MESA 1 TRANSECT C
.ttt. 21 20 » 18 17
CO
20
40
•0
NO
Ice
jgwo
140
MO
ISO
COO
Nd;
MESA 2 TRANSECT C
,STA. 21 20 19
MESA 3 TRANSECT C
STA. 21 20 19
220 -
Figure 5.11. Light scattering values, Transect C. Cross-hatching at a station location
indicates the depth of daylight interference with the nephelometer. Vertical
exaggeration = 250x.
-------
observed at "20 m and vertical temperature gradients (Fig. 5.12) were almost
nonexistent. The prominent discontinuity in the scattering contours at
station 18, however, was associated with a strong thermal front.
Although the scattering structure in August was similar to that of
November, the hydrography was considerably different. The halocline at
station 17 weakened considerably in August, whereas the vertical temperature
stratification became strong due to the warm summer runoff water. The
hydrography in March was somewhat intermediate of these extremes - vertical
salinity and temperature stratification were both present but moderate. The
lack of a prominent scattering structure was probably due to the abnormally
low runoff and consequently low sediment supply available during the spring
of 1977.
5.3.2.4 Transect C (sta. 24-27). These cross-sections off the mouth of
the Fraser River illustrate the steep scattering (Fig. 5.13) and temperature
(Fig. 5.14) gradients in both vertical and horizontal directions typical of
river plumes. Most of the river derived SPM near the river mouth was evi-
dently confined to the upper 5 m during November and August (no data avail-
able from March). Below the fresh water river plume at station 27, scattering
was relatively uniform or increased slowly with depth. South of the river
mouth lensing of turbid layers was quite common in November and August, but
largely absent during the low runoff period around March.
Because of the Fraser River influence, the vertical temperature gradients
were far more steep than any horizontal ones. The prominent lensing of SPM
observed at stations 24 and 25 during November can be correlated with the
weakening of the vertical temperature gradient moving southward from the
river mouth.
5.3.3 Suspended Particulate Matter Distribution -
Time Series Measurements
The 24-hr time series measurements made at selected stations (Fig. 5.1)
on each cruise are particularly valuable because they give the instantaneous
data from the transects a temporal perspective. The various stations reveal
differing degrees of variability which are in general related to their
proximity to major suspended sediment sources (i.e., Fraser River, Deception
Pass).
5.3.3.1 Strait of Juan de Fuca (sta. 9/10). Generalizations about this
locality are difficult, since poor weather aborted this station during
November and forced a station change to close inshore during August. The
time series at station 9 in March showed a persistent mid-depth minimum cen-
tered between 40 and 60 m (Fig. 5.15). Station 10A, in much shallower water,
showed simply a steady decrease in scattering with depth and uniform scatter-
ing levels for the duration of the observations. This locality was thus
relatively free of marked short-term variability during the observation
period in March and August.
5.3.3.2 Deception Pass (sta. 15). Station 15 was located In relatively
shallow water, near an important source of SPM, and within a strong and
32
-------
MESA 1 TRANSECT C
A. 21 20
19 IB IT
MESA 2 TRANSECT C
9TA. 21 20 19
MESA 3 TRANSECT C
STA. 21 20
19 18
Figure 5.12. Temperature values (°C), Transect C. Contour interval is 0.1°C for MESA I
and II, 1°C for MESA III. Vertical exaggeration = 250x.
-------
MESA 1 TRANSECT D
N24 STA. 25 26
27
MESA 2 TRANSECT D
24 STA. 25 26
MESA 3 TRANSECT D
. 24 STA. 25 26
180
200
20
40
60
80
;tOO
CL
Hi
O
120
140
160
180
200
Figure 5.13. Light scattering values, Transect D. Cross-hatching at a station location
indicates the depth of daylight interference with the nephelometer. Vertical
exaggeration = 250x. Note the high light scattering intensities and complex
layering due to suspended sediments from the Fraser River.
-------
MESA 1 TRANSECT D
.24 STA. 25 26
CO
in
200 -
MESA 2 TRANSECT D
24 STA. 25 26
27
MESA 3 TRANSECT D
.24 STA. 25 26
27
Figure 5.14. Temperature values (°C), Transect C. Contour interval is 0.1°C for MESA I
and II, 1°C for MESA III. Vertical exaggeration = 250x.
-------
3/11/77
MESA 2 STA. 9
1200 1600
08OO
160 -
8/9/77 0800
MESA 3 STA. 10A
1200 1600
2000 0000
Figure 5.15.
Time series line scattering measurements, station 9/10A.
The time (PST or POT) of each cast is shown by the vertical
lines. Times of high (40 and low (+) tide are shown
along the bottom border. Cross-hatching shows depth of
daylight interference. Shading shows position of various
mid-depth minima. Note the relative diurnal uniformity of
this location.
36
-------
variable current regime. These factors combined to produce rapid changes of
both concentration and structure in the observed SPM distributions (Fig. 5.16)
During the November cruise, the nephelometer profiles were stable during the
first 12 hrs with a well-defined mid-depth minimum. Very substantial changes
occurred during the following 12 hrs, including a pulse of very turbid water
which coincided with the ebb tide (Fig. 5.16). During March, surface scatter-
ing dropped considerably, whereas near-bottom values remained variable and
high. A mid-depth minimum was apparent during the last half of the time
series. Surface values were still low in August, a mid-depth minimum was
present throughout the time-series, and near-bottom scattering was again
highly variable. Surface water SPM concentrations at this locality, although
high compared to other regions in the study area, are still somewhat season-
ally variable due to changes in runoff volume. Bottom water SPM concentra-
tions evidently remain high throughout the year, probably due to resuspension
of bottom sediments by the strong tidal currents.
5.3.3.3 Cherry Point (sta. 17). During November, suspended matter
concentration was moderately stable for the first 12 hrs of observation and
developed a very intense mid-depth minimum (Fig. 5.17). Both surface and
near-bottom scattering values were relatively high and generally more uniform
than at station 15. Incomplete data from March do not indicate a mid-depth
minimum, and overall scattering values are low. The SPM distribution during
August was remarkably uniform, showing high surface values, moderate and uni-
form bottom values, and a very stable mid-depth minimum centered at ~15 m.
5.3.3.4 Fraser River (sta. 26). Station 26 (Fig. 5.18) shares many of
the characteristics of station 15, except that tidal currents are not nearly
as influential. During November, scattering was very high in the upper 5 m
due to the Fraser River plume. Below the plume the SPM distribution was uni-
form, with the development of a slight mid-depth minimum. Surface scattering
was the same in August, but the underlying water column had taken on an en-
tirely different character. The SPM distribution was extremely variable,
presumably due to sinking and entrainment of the surface plume. The lenses
of turbid water between about 10 and 25 m seemed relatively stable over the
24 hr time series, whereas the deeper lenses were more transitory, usually
being observed only on 2 to 3 successive casts.
5.3.4 Suspended Particulate Matter - X-ray Mineralogy
Mineralogic data from selected filter samples are given in Table 5.1.
Although the data are highly variable, some area-wide trends do emerge.
Stations within the influence of the Fraser River plume (20, 23, 26, 29, 31,
and 31A) tend to have lower values of chlorite/illite, quartz/ill He, and
feldspar/illite ratios than stations within the San Juan passages and Strait
of Juan de Fuca. Low values of all these ratios imply a relatively smaller
average grain size in the suspension. Samples collected from the Fraser
River (Dec. 1977) and the Skagit River (Nov. 1977) reinforce this areal dis-
tinction in mineralogy (see also Table 6.2). The Fraser River samples are
substantially lower in all three ratios than the Skagit River samples,
although it should be noted that these rivers were sampled only once during
the study period and the values obtained are not necessarily typical of the
three seasons sampled in the marine waters.
37
-------
11/18/76
MESA i STA. 15
O400 0800 1200
1600 200O OOOO
MESA 2 STA. 15
3/12/77 16OO 2OOO OOOO
04OO O8OO 1200 16OO
80
MESA 3 STA. 15
8/10/77 J200 1600 2OOO OOOO 04OO
°n?—V. I 'Jt vy i i _ \~f\—. >*Tiir-!!r
Figure 5.16.
Time series light scattering measurements, station 15
Symbols as in Figure 5.15. Note the higher variability
and scattering levels relative to the Strait of Juan de
Fuca location (Fig. 5.15).
38
-------
MESA 1 STA. 17
11/19/76. 0400 0800 1200 1600 2000 0000
3/14/77 0000
0
I 20
MESA 2 STA. 17
0400 0800
Q.
Ld
Q
40
1200 1600 2000 0000
T
I
I
MESA 3 STA. 17
8/11/77^ 1600 2000
^ 0
0000 0400 0800 1200
Figure 5.17.
Time series light scattering measurements, station 17.
Symbols as in Figure 5.15. Note the very weak structure
during MESA II compared with conditions during MESA I
and III.
39
-------
MESA 1 STA. 26
11/21/76 800 1200 1600 2000 0000 0400
MESA 3 STA. 26
8/13/77 0000 0400 0800
1200 1600
Q_
LxJ
Q
Figure 5.18.
Time series light scattering measurements, station 26
Symbols as in Figure 5.15. Note that the river plume*
is confined to the upper 5 m. Subsurface structure was
very complex during the high- runoff period during MESA III
40
-------
TABLE 5.1 X-ray mineralogy ratios of selected water samples and
centrifuge samples
Station Depth (m)
Chlorite
Illite
Quartz
Illite
Feldspar
Illite
MESA I
10 98
15 (0,10)2
8
(71,70)
72
8
Centrifuge
17 (0,10)
22
35
37
Centrifuge
26 0
0
42
51
Centri f uge
29 (0,10)
31 Centrifuge
31A - (0,10)
34 (0,10)
125
2.22
2.89
3.44
2.08
2.86
2.83
2.64
2.06
2.45
1.93
2.00
3.29
1.79
1.79
1.45
1.27
1.19
0.97
1.15
1.81
1.92
2.33
2.13
2.89
3.11
2.89
3.25
4.29
1.92
1.36
1.06
2.55
1.71
3.80
4.57
1.37
1.50
1.55
0.95
1.09
0.73
0.47
1.38
1.62
3.00
12.25
7.33/6.891
4.44
4.33/4.67
4.17
6.86
5.33
4.79
1.81
3.00
2.29
6.10/5.80
4.86
1.74
1.82
1.36
3.77
0.94
1.04/0.96
0.79
2.31
2.62
3.56/3.89
7.00
MESA II
9 (0,10)
(150,170)
3.10
2.00
(Contd.)
41
2.80
4.67
2.90
4.56
-------
TABLE 5.1 (Contd.)
Station
9
15
17
23
26A
35
Depth (m)
(150,165)
Centrifuge
(0,10)
(0,10)
73
(60,73)
Centrifuge
(0,10)
(0,10)
44
46
Centrifuge
(0,10)
119
(0,10)
188
(0,10)
Centri f uge
Chlorite
11 lite
1.80
2.31
2.50
2.80
2.50
3.20
1.71
2.08
1.89
2.08
2.45
2.46
1.55
1.81
1.07
2.13
1.80
2.52
Quartz
11 lite
1.53
1.92
3.40
1.93
2.33
3.20
2.00
3.00
1.22
2.77
3.82
2.54
0.80
2.31
0.36
2.19
0.50
2.35
Feldspar
111 He
1.93
1.92
5.60
3.53
4.50
4.50
2.57
2.31
1.78
2.69
5.00
4.46
1.10
2.63
0.71
2.56
1.30/1.40
2.96/3.04
MESA III
2
10A
15
(0,10)
47
50
Centrifuge
(0,10)
60
(0,10)
45
Centrifuge
2.71
2.30
2.09
2.10
2.60
2.64
3.37
1.95
2.50
(Contd.)
42
2.00
1.30
1.36
1.70
2.10
2.55
2.32
1.00
1.50
2.00
2.90
1.91
1.80
3.40
2.91/3.18
4.11
1.32
2.90
-------
TABLE 5.1 (Contd.)
Station Depth (m)
17 (0,10)
(0,10)
20
20
Centrifuge
20 (0,8.7)
163
26 0
0
0
77
79
Centrifuge
31 (0,10,20)
200
River Samples
Fraser River (Nov. 1977)
Skagit River (Oct. 1977)
Chlorite
Illite
2.44
2.43
1.85
2.00
2.50
1.13
1.77
1.39
1.04
1.56
, 0.98
1.21
1.27
2.06
1.60
1.71
4.00
Quartz
Illite
2.44
3.43
1.77
1.46
2.69
0.78
1.54
1.91
0.96
1.19
0.50
1.83
2.41
1.19
1.20
0.45
1.05
Feldspar
Illite
3.33
3.29
2.85
2.23
3.85
0.78
2.08
1.91
0.81
1.13
0.50
1.81
1.91
1.53
1.70
0.92
35.05
Indicates two principal feldspar peaks.
Indicates 'pooling of samples from different depths.
43
-------
5.3.5 Particle Size Distributions
Particle size analyses (Fig. 5.19) were performed by Coulter Counter
techniques on six samples collected by centrifugation for analysis of sus-
pended hydrocarbons. Samples suitable for analysis were collected during
MESA I at stations 15 and 26, during MESA II at stations 9 and 17, and during
MESA III at stations 17 and 26. Although the median diameters of all but one
of the samples are similar at 5-6 ym (sta. 17, MESA III, is higher at ~11 ym),
stations 15, MESA I, and 17, MESA III, possess prominent peaks in the 50-
70 ym diameter range. This peak may be due to biogenic fragments (such as
diatoms) and/or rock fragments of quartz and feldspar.
5.4 SUMMARY
Typical values of the concentration of total suspended solids in the
waters of the study area between November 1976 and August 1977 were 0.5-
2 mg/Ji. Significant local modification of this concentration level in sur-
face waters occurred north of the San Juan Archipelago, within the influence
of the Fraser River plume, where concentrations were as high as 8 mg/£, and
immediately seaward of Deception Pass, where concentrations were ~2-3 mg/fc.
Concentration values in the mid-depth and bottom waters showed little influ-
ence from riverine sediment sources.
The total particulate load in the study area, based on an estimated
water volume of "250 km3 (estimated from calculations of the Strait of
Georgia volume made by Waldichuk, 1957) and an overall SPM concentration
average of 1.5 mg/£ is approximately 4 x 1011 g. Because of the unusual
climatological year during the study period, which resulted in a substantial
decrease in fresh water runoff (Fig. 2.2) compared to a normal year, the
relationship of this estimated total SPM load to other years is uncertain.
The typical vertical distribution of SPM throughout the area tended
towards relatively high values in the surface and bottom waters and rela-
tively lower values in the mid-depth regions. This distribution is pre-
sumably due to different agents of particle production in different layers
of the water column: high phytoplankton growth and fresh water runoff in
the surface waters, and substantial contribution from resuspended bottom
sediment into the bottom waters. Confirmation of this hypothesis - particu-
larly the nature of the SPM increase in the bottom water - would require
chemical analyses which were not undertaken in the present study.
Temporal variability of the SPM distributions was examined both on a
seasonal and diurnal basis. Seasonal variability over most of the region
was negligible: overall SPM concentrations were 1.8 ± 2.4 mg/i for MESA I
1.4 ± 0.8 mg/£ for MESA II, and 1.2 ± 1.0 mg/£ for MESA III. The somewhat
higher mean value and standard deviation for MESA I is the result of very
high SPM values near the Fraser River and Deception Pass during November 1977.
Diurnal variability was most pronounced at locations where strong tidal
currents and/or major sediment sources (Fraser River, Deception Pass) were
present. At other locations the vertical SPM distribution was relatively uni-
form over short time scales.
44
-------
MESA I
STA 15 D
STA 26 O
i
MESA II
STA 9 •
STA I7A
14-
12-
IO-
6-
z-
t IO
MESA III
STA 17 A
STA 26 O
SO IOO
Figure 5.19.
MEAN DIAMETER dim)
Coulter Counter particle size distributions from six
centrifuge samples. Note the peak in the coarse silt-
fine sand range (50-70 wm) for stations 15, MESA I,
and 17, MESA II.
45
-------
6. OIL-SEDIMENT INTERACTIONS
6.1 GENERAL STATEMENT
Oil spilled onto the surface of the ocean is acted upon by several
physical processes including evaporation, emulsification, solution, and the
injection of oil particles into the atmosphere during bubble formation
(Kreider, 1971; McAuliffe, 1966, 1969; Baier, 1970). Except for solution of
the soluble fraction, these processes represent a physical transfer of
petroleum from the aquatic environment, thus reducing its potential impact
on marine organisms. In contrast, petroleum adsorbed onto particles becomes
entrained in the water column and ultimately deposited on the bottom.
There is very little published information about the processes by which
oil is transported in association with suspended particles or the quantities
of oil that can be adsorbed onto the particles. Early investigators have
shown that flocculation of oil bears an inverse relationship to salinity
(Chipman and Galtsoff, 1949; Hartung and Klinger, 1968). Later investigations
indicate that sedimentation of oil involves a two-step process (Bassin and
Ichiye, 1977). This process begins with the adsorption of oil onto the sus-
pended particles and is followed by the flocculation of these oil-sediment
emulsions by electrostatic interactions. The amount of oil that can be
sedimented by a specific quantity of suspended matter appears to be dependent
upon the physical and chemical nature of the suspended particles as well as
the amount of naturally-occurring organic matter that is associated with the
particles (Poirier and Thiel, 1941; Meyers and Quinn, 1973).
Oil adsorbed onto the surface of particles is one of the principal
mechanisms by which petroleum contaminants may be ingested by marine orga-
nisms (NAS, 1975). Of particular concern is the effect on planktonic and
benthic detrital feeders. Conover (1971) observed following the wreck of
the tanker Arrow in Chedabucto Bay that zooplankton could graze as much as
20% of the oil particles less than 1 mm in diameter and sediment them as
fecal material. Parker (1970) also found that copepods and barnacle larvae
could encapsulate oil as fecal material. Because fecal material is an impor-
tant food source for other members of the food chain, oil transmitted to the
bottom in this form becomes an important mechanism by which benthic detrital
feeders may be impacted by oil. Many of these species, including shrimp,
clams, oysters, and crabs, are of economic interest.
In most previous studies, the adsorption of petroleum components from
solution by various clay mineral phases has been investigated. The results,
as typified in the report by Meyers and Quinn (1973), show that approximately
6% of a fuel oil solution was taken up by Narragansett Bay sediments, but the
amount increased to 51% when bentonite clay was substituted. Temperature,
salinity and concentration of organic matter play important roles in deter-
mining the quantities of oil in solution adsorbed. These results are not
surprising in view of the low solubility of petroleum hydrocarbons, particu-
larly the long chain aliphatics.
46
-------
The purpose of this study was not to clarify the adsorption phenomenon
from true solution, but rather to investigate the agglutination process asso-
ciated with natural suspended material and surface or emulsified oil. In
spill situations, excess oil is present on the surface of the water and may
be readily accommodated by suspended particles that come in contact with the
surface layer. The first step in characterizing the agglutination process is
to establish the capacity of natural material for oil as a function of
selected environmental parameters. This approach avoids the question of
kinetics, but does establish a fundamental criterion for assessing the load-
ing characteristics of the sediment.
6.2 LABORATORY STUDY
In the preliminary design of the experiment, various quantities of oil
were mixed with known amounts of riverine-derived suspended matter under con-
trolled laboratory conditions. Suspended matter was retrieved from both the
Skagit and Fraser Rivers with a continuous flow centrifuge, the efficiency of
which will be discussed in greater detail below. The amount of sediment
chosen for the experiment was nominally 50 mg, resuspended in 600 m£ of Puget
Sound sea water. This concentration of sediment is high and not representa-
tive of the concentrations actually observed in the waters of "Northern Puget
Sound," except possibly in the river estuaries, but represented a convenient
amount with which to effectively carry out the preliminary measurements. The
quantities of oil added were adjusted to give oil:sediment loadings of 0.2 to
3, or 20 mg to 150 mg of added oil.
The procedure was as follows: Approximately 50 mg of riverine suspended
matter was added to 600 mi of sea water in a separatory funnel and placed in
a controlled temperature bath. After thermal equilibration, the desired quan-
tity of oil was added to the system, tightly stoppered, and the mixture shaken
gently for 1 hour. The intensity of shaking was controlled to avoid over-
development of oil-water emulsion. After 1 hour, the mixtures were allowed
to stand in the water bath until the sediment/oil floes had settled, at which
time settled material was carefully removed with a long pipette and extracted
with methylene chloride. The remaining mixture (unsettled sediment, oil, and
water) was back extracted with methylene chloride to recover the remaining
oil. Organics associated with the sea water and the sediments were esti-
mated in separate experiments. The amount of sediment recovered from the
lower layer is used as the basis for computing the loading (i.e., mg oil/mg
sediment): The total quantities of oil recovered from each step was deter-
mined by gravimetry on a CahnR microbalance. Most of the experiments were
conducted in triplicate and repeated if either the oil recovery or sediment
recovery was judged to be low.
6.3 METHODOLOGY
6.3.1 Petroleum Hydrocarbon Analysis
Qualitative analysis of the alkane fraction was carried out to evaluate
gross compositional variations that might occur during the agglutinization
47
-------
process. Extracts from the settled oil/sediment floes were subdivided into
two fractions (alkanes and aromatics) by silica gel chromatography. The re-
sulting alkane fraction was analyzed by glass capillary gas chromatography
according to the procedures established by Macleod et al. (1976). Because
the quantities of sediment being extracted were less than 1 g, the solvent
extraction volumes were reduced to l/10th those recommended by the above
procedure.
6.3.2 Oil Recovery Efficiency
Preparatory to the study, it was necessary to establish the reliability
of various experimental procedures related to the recoveries of oil. The
first of these dealt with determining the reliability of weighing crude oil
quantitatively on a Cahn^ microbalance. The results of this experiment are
shown in Figure 6.1, where approximately 25 y£ of Prudhoe Bay crude oil was
pipetted into a tared aluminum pan at room temperature and its weight deter-
mined as a function of time. The largest change in weight occurred during the
first 10 mins., after which time the rate slowed appreciably. Ten minutes
was chosen as a convenient time at which to weigh the oil residue. Extrapola-
tion of the curves in Figure 6.1 show that less than 5% of the total oil was
lost during the first 10 mins. The observed loss in weight presumably re-
flects the volatilization of the low molecular weight aliphatics and aromatics.
£22
20
UJ
18
16
APPROX. 25 ul
PRUDHOE BAY CRUDE
**2L—-TIME OF WEIGHING
8 12 16
TIME (min.)
20 24
Figure 6.1.
Evaporative weight loss of Prudhoe Bay crude oil
Two curves shown are replicate experiments.
48
-------
The extraction and concentration efficiencies were also investigated
(Table 6.1). In the first case various amounts of Prudhoe Bay crude oil were
added to 60 mi of methylene chloride, reduced to 2 ma in a concentrator tube,
solvent exchanged for hexane, and the volume again reduced to 2 mi. A 50 m£
aliquot of this solution was evaporated on a tared pan at room temperature and
weighed on a CahnR microbalance. The corrected concentrations of oil recov-
ered are shown in column A. The average for three concentrations of oil was
82%. The material lost (approx. 18%) presumably represents the light fraction
of the oil.
TABLE 6.1 Extraction and concentration step efficiencies.
(A) Various amounts of Prudhoe Bay crude oil were added to
60 mi CH2 C12 and reduced to 2 m£ volume in hexane.
(B) Various amounts of oil were added to 600 mi of Puget
Sound sea water and backextracted with 3-20 m£ aliquots of
CH2 C12. Average percent recoveries and standard deviations
are shown together with the number of replicate experiments
in parentheses.
Amount Oil Added
mg A
% Recovery
8.45
16.90
25.35
42.25
84.45
83 ± 6 (6)
86 ± 6 (6)
77 ± 13 (5)
—
--
57
67
62
73
75
± (1)
± 4 (2)
± 4 (2)
± 9 (5)
± 10 (6)
6.3.3 Sediment-Sea Water Organic Matter Corrections
During the extraction process, a portion of the organics associated with
the aqueous phase (i.e., DOC) and the solid phase (i.e., organic matter) was
coextracted with the oil. In order to correct for this effect, which results
in an overestlmation of the quantity of oil recovered from each phase, sedi-
ment (50 mg) and water (600 mi) were extracted separately with 3-20 m£ ali-
quots of methylene chloride. The amount of organics so extracted were
determined gravimetrically on a CahnR microbalance. Our results show that
the concentration of extractable organics in the sea water medium was approxi-
mately .002 mg/m£ sea water; the concentration of extractable organics from
the sediment was approximately .006 mg/mg sediment. Organics coextracted in
the sediment and water layers were calculated based on water volumes and
sediment recoveries in each fraction.
49
-------
The above correction represents a rather crude estimate of the partition-
ing of the organics between the various phases. The mixing of sea water-oil-
sediment represents initially a three-phase system. Organics will be
redistributed among the various phases depending on their solubility in water
and oil and their relative adsorption affinity for the solid phases present.
No attempt was made to characterize the actual distribution of the organics
present in the various phases.
In column B is shown a measure of the extraction efficiency. Various
quantities of oil were added to 600 m£ of Puget Sound sea water and back-
extracted with 3-20 m«, aliquots of methylene chloride. The volume was
reduced to 2 ma in a concentrator tube and the solvent exchanged for hexane
as before.
There appears to be a systematic increase in the extraction efficiency
as the concentration of oil increases. The reason for this has not been
explored further, but may be a function of the solubility of the oil and the
quality and amount of dissolved organic carbon (DOC) present. In a separate
experiment, we determined that the extraction procedure outlined above re-
moved approximately 2.3 mg/i of organic matter present in the sea water
used. Results shown in column B have been corrected for extractable organics.
The difference in recoveries noted between the concentration and extraction
steps presumably reflects the relative extraction efficiency as a function of
the oil concentration and serves as a basis for interpreting total oil recov-
eries to be discussed below.
6.3.4 Sediment Morphology and Compositional Characteristics
The matrix for the oil agglutinization studies was suspended material
from the Skagit and Fraser Rivers. Sampling was conducted in the lower
reaches of the rivers, but above the salt wedge, in order to obtain repre-
sentative material actually entering the estuary.
Sediment recovery was effected with a Sorvall^ model SS-3 high speed
continuous flow centrifuge operated nominally at 15,000 rpm and a fluid flow
rate of 400-500 mi min"1. At this orbital velocity, particles are subjected
to approximately 30,000 G's of acceleration. Because the sedimentation
efficiency of individual particles is a function of both the density differ-
ence between particles and the fluid and their size, organic matter, having
a density near that of water, is not recovered as efficiently as mineral
matter.
Water was pumped to the centrifuge through a sampling manifold consisting
of two prefliters, the smallest of which was 100 pm. This procedure effec-
tively rejected larger pieces of vegetable matter that would have heavily
biased the compositional analysis. Flow rate and accumulated volume through
the centrifuge were monitored electronically.
The centrifuge, intake manifold, and flow monitoring system is shown in
Figure 6.2. For shipboard operations in the Straits of Juan de Fuca and
Georgia, it was necessary to gimbal the centrifuge to reduce accelerations
due to the pitch and roll of the ship.
50
-------
Pressure
Gauge
Centrifuge
Intake
Two-Stage
Prefilter
Figure 6.2.
Suspended matter recovery system. Suspended solids are
pumped to the intake manifold and passed through a two-stage
prefilter (dia. < 100 pm). Flow rate and accumulated volume
through the centrifuge are monitored electronically. Centri-
fuge is shown mounted in gimbal for use at sea.
51
-------
In order to assess the sediment extraction efficiency of the centrifuge,
the ambient water and the effluent from the centrifuge were filtered and
analyzed for total suspended matter (TSM), total carbon and nitrogen, parti-
cle size frequency, and mineralogy (see sections 5.3.4 and 5.3.5).
Water samples were taken from the intake manifold and from the centrifuge
outflow for the analyses of TSM, organic carbon and nitrogen, and particle
size frequency. Aliquots were vacuum filtered through three different fil-
ters: 47 mm diameter, 0.4 ym pore size Nuclepore" polycarbonate filters for
total suspended matter concentration determinations; 25 mm diameter, 0.4 \an
pore size NucleporeR polycarbonate filters for particle size analysis; and
25 mm diameter, 0.45 ym pore size SelasR silver filters for particulate car-
bon and nitrogen analyses. All samples were rinsed with three 10 ms, aliquots
of distilled, deionized, membrane filtered water, then placed in individual
plastic petri dishes with, lids slightly ajar for desiccation and then sealed
and stored (silver filters frozen) for subsequent laboratory analysis.
The NucleporeR filters were weighed on a CahnR Model 4700 electrobalance
before and after sample filtration with the suspended masses being determined
by difference. Particulate carbon and nitrogen were analyzed by the micro-
Dumas combustion method, employing a Hewlett Packard 185B C-H-N analyzer
(Sharp, 1974).
The compositional parameters of the river-derived suspended matter is
shown in Table 6.2, together with the mineralogies. The Skagit River was
visited in May and November of 1977, representing two widely differing hydro-
logic conditions. In May, the river was extremely low and suspended loads
averaged only 5.5 mg/i. In 1975, the mean concentration of suspended matter
in May for the Skagit River was approximately 60 mg/£ (see Fig. 2.3). The
low concentration of suspended matter observed in May of 1977 reflects the
anomalously low precipitation that occurred in the Skagit River drainage
basin during the winter of 1976-1977. In contrast, the November sampling
was carried out at a time following several weeks of heavy rain. The sus-
pended loads were extremely high as a result of soil erosion in the lower
alluvial basin. The mean concentration of suspended matter was 134 mg/i;
its organic carbon content was 2.3%.
A comparison of the concentration of suspended matter in the effluent to
that in the ambient water shows that more than 92% of the filterable material
was removed by centrifugation in May; 98% in November. The higher figure in
November reflects the increased abundance of larger, more dense particles,
and a lower concentration of organic matter (see Table 6.2).
Scanning electron micrographs of filtered material derived from the
Skagit River and the centrifuge of effluent are depicted in Figure 6.3a,b
(November 1977). Material from the ambient water (Fig. 6.3a) shows particles
as large as 20 ym (1000 X magnification), although most of the material
appears to be less than 5 ym. A statistical number of these particles were
counted with a Zeiss Particle Size Analyzer and the results are shown in
Table 6.3. Of the particles counted, 37% were less than 2 ym in diameter,
whereas 97% of the particles were less than 10 ym.
52
-------
TABLE 6.2 Comparison of the concentrations of total suspended matter (TSM) in the
ambient water with that in the centrifuge effluent. Also shown are the
concentrations of total carbon in the suspended material, its carbon:
nitrogen ratio (C:N), and the chlorite:illite, quartzrillite, and feldspar:
illite ratios.
Location
Date
Volume
Centrifuged
(liters)
TSM
(mg/£)
Ambient Effluent
Total
-------
Figure 6.3. Scanning electron micrographs of Skagit River suspended
matter showing particles recovered in the ambient water (a)
and in the effluent from the centrifuge (b). Note the
pores in the Nuclepore®0.4 um membrane filter used in the
recovery efficient test. Particles are shown lOOOx actual
size.
54
-------
Table 6.3 Representative particle size distributions from the Skagit
and Fraser Rivers. Values are expressed in terms of
cumulative percent within a size classification
Cumulative Percent
Sample Location <2 urn <5 ym <10
Skagit River
November 1977 37 83 97
Fraser River
December 1977 55 94 99
Figure 6.3b shows a similar scanning electron micrograph of the material
filtered from the centrifuge effluent. When subjected to higher magnification
(10,000 X, not shown), the morphology of the particles was poorly defined as
they appeared to be coated with an organic gel-like material. It is this
material that results in the clogging of the pores of the filter, resulting
in the retention of many particles less than 0.4 urn, the nominal pore size.
Most of the particles shown in Figure 6.3b are <_ 0.4 um. Analyses for
organic carbon and nitrogen were negative as sufficient material was not
present on the filter to obtain a measurable chromatographic response
(Table 6.2).
The scanning electron micrographs of suspended sediment derived from the
Fraser River are shown in Figures 6.4a,b. In contrast with Figure 6.3a the
filterable material from the Fraser River is, on the average, smaller in size
than that obtained from the Skagit. Approximately 94% of the retained mate-
rial was less than 5 ym in diameter as compared to 83% for the Skagit River
(Table 6.3). This is not surprising, since the turbulent energy was much
higher in the Skagit River at the time of sampling, relative to conditions in
the Fraser. Figure 6.4b depicts the material passing through the centrifuge
and is similar in morphology to that obtained in the Skagit (see Fig. 6.3b).
Particle size determination of the riverine suspended matter was calcu-
lated using photomicrographs taken on an ISIR Super Mini SEM-II scanning
electron microscope. The particles were then sized (assumed to be spheres)
on a ZeissR TGZ-3 particle size analyzer. In section 5.3.5, the particle sizes
were determined with a Coulter Counter, which measures the effective volume of
the particle, rather than the nominal diameter as done here. If the particles
analyzed by both methods were perfect solid spheres, the calculated median
diameters would be nearly the same; but, of course, the morphology of the
particles is not uniform as is vividly shown in Figures 6.3 and 6.4. No
intercalibration of the two procedures was carried out, but a systematic dif-
ference in the calculated median diameters is expected.
55
-------
Figure 6.4.
Scanning electron micrographs of Fraser River suspended
matter showing particles recovered in the ambient water (a)
and in the effluent from the centrifuge (b). Particles are
shown lOOOx actual size.
56
-------
In summary, it appears that the continuous flow centrifuge collects
representative samples of suspended matter from the rivers studied, but may
bias the composition of the material in favor of the detrital inorganic frac-
tion. This is particularly true if the organic particles are less than 1 ym
in diameter.
6.4 RESULTS
6.4.1 Skagit River Sediments
The oil agglutinization studies, using Skagit River suspended material,
is summarized in Table 6.4. In each experiment, approximately 50 mg of sedi-
ment was added to the quantities of oil shown in column 1 of Table 6.4. Tem-
perature was maintained at 10° and 15°C, respectively, for each suite of
experiments.
Table 6.4 The concentration of sediment-accommodated Prudhoe Bay crude oil
for various initial oil loadings. All experiments were carried
out in 1 a separatory funnels to which was added 600 m£ of sea
water (S 32 /oo) and 50 mg of Skagit River suspended sediment.
Sediment recovery in the lower layer and total oil recovery are
also shown in columns 2 and 4. Number of replicate experiments
is shown in parentheses in column 1.
Amount of Oil
Added
(mg)
8.9
17.7
26.6
44.4
133.0
17.7
44.4
(7)
(5)
(6)
(ID
(3)
(3)
(3)
Sed. Recovered Oil Recovered
Lower Layer Lower Layer
% %
73 ±
76 ±
78 ±
83 ±
86 ±
73 ±
73 ±
19
4
5
4
2
2
2
Temperature
20 ±
30 ±
22 ±
28 ±
31 ±
Temperature
18 ±
12 ±
10°C
10
7
6
6
2
15°C
4
2
Total Oil
Recovered
%
43 ±
54 ±
72 ±
86 ±
93 ±
58 ±
85 ±
18
9
5
5
4
1
6
Loading (La)
mg oil/mg sed.
.07 ±
0.14 ±
0.15 ±
0.30 ±
0.96 ±
.08 ±
0.15 ±
.02
.04
.04
.05
.02
.02
.03
57
-------
Sediment recovery, as reflected in column 2, shows that more than 70% of
the total sediment added was removed in the lower layer, although the recovery
efficiency increased systematically with the amount of oil added. Presumably,
the large floes of oil and sediment formed at higher concentrations of oil
were effective in sieving the finer particles from suspension.
In the experiment conducted at 10°C, the oil loading (mg oil/mg sed.)
increased monotonically from .07 mg/mg to 0.96 mg/mg as the amount of oil was
increased from 9 mg to 133 mg. This situation is graphically displayed for
both 10°C and 15°C in Figure 6.5. Ignoring for the moment the apparent pla-
teau in the curve, which may be an experimental artifact, the linear regres-
sion line for all points was La = 0.36 Lg - .01, where La is the loading or
the amount of associated oil per unit weight of sediment recovered and L0 is
the initial oil/sediment weight ratio. At 15°C, the quantity of oil recov-
ered per weight of sediment recovered (l_a) decreased by approximately 50%,
implying a large temperature effect.
Although the curve in Figure 6.5 shows a linear relationship up to
La = 1, it is unlikely that this trend would continue. If we assume a density
for the adsorbed oil of 0.89 g cm'3 and that for the suspended matter of
2.5 g cm~3, the mean density of the floes would be 1.7 g cm 3. At La = 10,
an unlikely situation, the mean density would be 1.04 g cm"3, and the parti-
cles would be almost neutrally buoyant in sea water (p = 1.026 g cm"3).
Also shown in Table 6.4 (column 4) is the systematic increase in the
total recovery of oil as the concentration increases. As stated previously,
the reason for this is not understood, since methylene chloride has been
used by several investigators to extract petroleum hydrocarbons from sea water
(Gordon and Keizer, 1974; Hites and Biemann, 1972). Experiments in our lab-
oratory have shown that quantitative recovery of oil from distilled water can
be achieved but apparently not in sea water containing suspended sediments.
The reason for this may be due to a complex interaction between the oil and
organic phases present in the sediments and water. This aspect of the study
needs clarification.
During the agglutinization process, various components of crude oil may
partition themselves between the adsorbed phase and the emulsified fraction.
To investigate this possibility, sedimented oil was extracted from the mineral
phases and analyzed for its paraffin composition. The results of this analy-
sis are shown in Figure 6.6. For comparison, a similar amount of Prudhoe Bay
crude oil was fractionated into its saturated and unsaturated fractions; the
paraffin fraction was analyzed as stated above. These results are reflected
in Figure 6.7. Both chromatograms show the predominance of the C15-C18 normal
paraffins, and if any fractionation has occurred, it resides with the light
fraction. Because of their volatility, quantitative recoveries are not
reliable. It is also important to note the absence of an unresolved complex
mixture, even with fresh crude oil. The numerous small peaks present are due
to branched alkanes and cycloparaffins (Clark and MacLeod, 1977).
Under the short-term conditions of this experiment, little fractionation
of the oil was observed (i.e., closed systems, 10°C, flocculation time: 1
hour). Exceptions include the vaporization and solution of the more volatile
58
-------
1.2
^ 1.0
Q)
-------
14 15
20
21
22
w
23
JA
24
u
25
U
2
u
6
27
t*
28
29
WJL 1
30
JUiuJL^JL^
32
Figure 6.6. Gas chromatogram of the extracted aliphatic fraction taken from oil flocculated
sediments. The amount of oil added was 44.4 mg; the temperature 10°C.
-------
Figure 6.7. Gas chromatogram of the aliphatic fraction of Prudhoe Bay crude oil. The
amount of oil was adjusted to give a response similar to that shown in Figure 6.6.
-------
components (< C12). In a natural circumstance where physical, chemical, and
biochemical weathering of the oil would occur, the composition of sedimented
oil would change significantly with time.
6.4.2 Fraser River Sediments
The oil agglutinization studies conducted with Fraser River suspended
matter are summarized in Table 6.5 and Figure 6.8. Both normal sea water and
water free of dissolved organic carbon were used in the study. Salinity and
temperature in all experiments was 32°/oo and 10°C, respectively. The initial
amounts of oil added were varied from 18 to 89 mg, resulting in loading ratios
of 0.36 to 1.78 (L0). Number of replicate experiments is shown in parentheses
under column 1 of Table 6.5.
Sedimentation of oil by Fraser River sediments was not linearly propor-
tional to quantity of oil as shown with Skagit River sediments. The maximum
loading of 12% was observed at L0 = 0.36 (Fig. 6.8), and decreased uniformly
to 7% at higher concentrations of oil. Quantities of sediment recovered
also decreased slightly from 67% to 51% of the total added. It was observed
visually that much of the oil sediment was floating on the surface of the
water and did not settle during the course of the experiment. As more oil
was added, the surface slick became larger and accommodated a greater number
of the particles.
Suspended sediments derived from the Fraser River were smaller in size
(Table 6.3) and mineralogically distinct from sediments taken from the
Skagit River (Table 6.2). The median diameter of the Fraser River material
was 1.8 ym compared to 2.6 \an in the Skagit River sediment. Mineralogically,
Fraser River suspended sediments were relatively rich in clay minerals, with
lesser amounts of elastics (i.e., rock fragments, quartz, feldspar) than
observed in the Skagit River material (Table 6.2). Thus, the smaller amount
of oil sedimented with fine-grained material is provisionally ascribed to
mineralogical differences and particle size. A more thorough discussion of
these effects and others will be presented below.
Dissolved organic carbon was removed from the sea water to assess its
effect on the interaction between oil and sediment. Dissolved organic carbon
was removed from sea water by passage through activated charcoal according to
a modified procedure of Jeffrey and Hood (1958). Subsequent extraction of
the water with methylene chloride indicated that approximately 1.6 mg/A of
organic carbon was removed, or about 70% of the original amount. Although
present in small amounts, relative to the concentrations of oil used, DOC
may be rich in surfactants and thus appreciably influence the behavior of oil
with sediments.
The removal of dissolved organic carbon appears to have had little
effect, except at the highest initial oil loading (89 mg oil added), on the
amount of oil retained on the settled sediments. With an initial oil loading
of 1.78, approximately 17% of the sediment weight aggultinated oil. This
represents approximately 25% of the oil that was sedimented by Skagit River
sediments under the same conditions (Fig. 6.5). Effect of particle size is
again clearly evident as approximately 50% of the sediment was recovered in
62
-------
0.2
0>
to
E 0.1
0
Without DOC
With DOC
T= IO°C
0.4 0.8 1.2 1.6 2.0
L0 (mg oil/mg sed.)
Figure 6.8.
Concentration of accommodated Prudhoe Bay crude oil (La)
on Fraser River suspended sediments as a function of the
initial oil loading (Lo). Experiments were performed in
normal Puget Sound sea water (S = 32°/oo) and in sea water
which had 70% of its extractable DOC removed. In each
experiment, the concentration of suspended sediments was
83 mg/i.
63
-------
Table 6.5 Accommodation of Prudhoe Bay crude oil on Fraser River suspended
sediments at 10°C and 32°/oo. Comparisons are made between
normal sea water and DOC-free sea water. Number of replicate
experiments is shown in parentheses under column 1.
Amount Oil
Added
(mg)
17.7 (3)
44.4 (3)
88.7 (2)
17.7 (4)
44.4 (1)
88.7 (2)
Sediment
Lower
(
67
60
51
52
56
47
Recovered
Layer
X)
NORMAL
± 4
± 4
± 10
DOC
± 1
± 1
Oil Recovered
Lower Layer
SEA WATER
21 ± 3
5 ± 2
2 ± 0
ABSENT
16 ± 2
4
5 ± 1
Total Oil
Recovered
(*)
46 ± 12
92 ± 8
92 ± 5
57 ± 3
84
86 ± 13
Loading (La)
mg oil
mg sed.
0.12 ± .01
.07 ± .03
.07 ± .00
0.11 ± .01
.06
0.17 ± .00
all three experiments (Table 6.5) compared to more than 80% in the aforemen-
tioned experiments (Table 6.4).
The relationship shown between the quantity of oil added and the amount
sedimented is subject to further interpretation (Table 6.5). If the single
value at L0 - 0.88 is low, then the provisional interpretation of the plot
is that the removal of DOC has the apparent effect of increasing the accommo-
dation of oil on sediment. It appears that the effect is not great, however.
An explanation of this phenomenon would be that surfactant compounds present
in the DOC fraction have diminished the interfacial energy between mineral
particles and oil droplets. Because an oil-in-water emulsion is unstable,
the coated particles rapidly coalesce into floes. These few data only suggest
this mechanism.
6.5 DISCUSSION
Clay minerals and quartz sols (presumably other rock forming minerals as
well) usually possess a net electrical charge, brought about by charge dislo-
cation or imperfections within the crystal lattice, or "broken bond" surfaces
created by the fracture of mineral grains (Van Olphen, 1963). In the latter
64
-------
case, cations or unions may be adsorbed or chemisorbed to the surface to
satisfy the electrical imbalance. The net effect is that the mineral grains
repulse each other due to their like charges. Counteracting this force is
Van der Waal's force which tends to minimize the surface-free energy of the
individual particles through particle agglomeration or growth (Castellan,
1964). In an ionic medium, such as sea water, the electrical double layer
is compressed, and the particles are said to flocculate under the effect of
Van der Waal's forces.
When oil is added to an ionic clay sol, complex behavior of the system
is observed and not readily predictable by theory. How the system behaves
depends on the specific interactions between the oil and water, oil and par-
ticles, and water and particles. In turn, these relationships depend on the
composition of the aqueous medium, size and mineralogy of the particles,
presence of surfactants, and the composition of the oil.
In an early study by Poirier and Thiel (1941), numerous natural materials
(e.g., shale, silt, bentonite, humus soil, etc., to name a few) were selected
and evaluated as to their adsorptive behavior toward a typical Mid-Continent
crude oil. Selecting deflocculation times of 30 minutes (1 hour in this
study), their results show that the oil loadings ranged from 0.6 to 2.2 g oil
sedimented for each gram of solid phase added. Kaolin accommodated the larg-
est amount of oil (not at low flocculation times, however), oil shale the
least. Fine-grained material ,(< 125 y) entrained more oil than coarser mate-
rial (> 125 y). This latter result is not necessarily at variance with our
own, since the two riverine sediments examined in this report were consider-
ably smaller than 125 y (see Table 6.3). Entrainment of up to 1 mg oil/mg
sediment in our experiments is within the above range, even though amounts of
oil (2.2 g) and sediment (1.0 g) used in the aforementioned studies were much
larger than in ours.
Poirier and Thiel (1941) also observed that oil shale accommodated oil
poorly and attributed this to the presence of organic acids and the larger
particle size of the shale. If amphipolar molecules were present in the oil
shale, as suggested by Poirier and Thiel, the interfacial tension would have
been reduced and the oil would, in effect, coat the surface of the clay par-
ticle and assume its shape. This was apparently observed, although the
amounts of oil transported downward were less than with other substances
tested (La - 0.8). All of our experiments showed visually that the oil-
sediment floes consisted of attached plates forming a card-house structure.
This would.imply that surfactants in the oil, or possibly interfacially-
active compounds in the oil, were important in the flocculation process.
Bassin and Ichiye (1977) proposed that oil forms colloidal electrolytes
with cations in sea water (e.g., Na+) and is subsequently bonded electro-
statically to the surfaces of clay minerals. Although stated somewhat dif-
ferently, Van Olphen (1963) describes the replacement of double layer
cations (e.g., Na+) with an organic cation, such as an amine salt, thus
forming an adsorbed or chemisorbed film of oil. The differences between
these two mechanisms appear to us to be subtle and lead to the same effect.
65
-------
Because these particular mechanisms imply a thin-surface film of oil on
the particle, rather than the trapping of oil by settling floes, Bassin and
Ichiye (1977) estimated the loading of oil expected on kaolinites and mont-
morillonites, assuming a film thickness of 20-50 A. The amount thus
entrained by sediment particles was 0.25 mg oil/mg sediment to 3 mg oil/mg
sediment; the range of values agrees rather well with our data. The authors
also point to the importance of trapped oil globules in the interstices of
the floes, which will increase the burden of accommodated oil. It remains to
be shown that significant concentrations of colloidal electrolytes can be
formed from oil in sea water and thus provide a basis for the suggested mecha-
nism.
In a simple system composed of charged particles in an ionic medium,
flocculation occurs when the attractive forces exceed the repulsive electro-
static interactions between particles (Van Olphen, 1963). Huang and Elliot
(1977) investigated the electrophoretic mobility of several crude oils and
inorganic particles (e.g., silica, kaolinije, A1203, etc.) and all but the
aluminum oxide phases were found to be negatively charged at a pH typical of
sea water (< 8.5). Zero-point charge of silica and kaolinitic solid phases
occurred at pH = 2. Their studies show that the negatively charged particles
were transported to the surface of the oil, in spite of the repulsive charges,
but amounts of settled oil were apparently small relative to dispersed oil
(Huang and Elliot, 1977). The amount of settled oil was only shown for the
Cabosil (silica phase) system in which no more than 4% of the original oil
was accommodated on the settled fraction. This was an unfortunate choice of
solids for our purposes because the particle size of this material was .007 -
.014 ym, at least two orders of magnitude smaller than our median particle
size. Should no oil have been added to the system, it is unlikely that much
of this material would have settled over the duration of the experiment.
Cabosil was found to armor the oil particles against coalescence and thus
increase the stability of the oil emulsion. We did not observe this predic-
table phenomenon, since concentrations of solids were not varied. It is
interesting to note that in the Cabosil system, approximately 30% of the oil
extracted was recovered from a surface slick, to which was presumably attached
some of the particles. This was the case with Fraser River sediments in which
the finer-grained material was observed attached to the surface slick.
Increasing the concentration of the solids resulted in a destabilization
of the emulsion and greater quantities of oil were transported downward with
the settling particles. Unfortunately, these quantities were not tabulated,
except in the case cited above, and cannot be compared with our observations.
The study of Huang and Elliott (1977) makes a very crucial point. That
fact is that negatively charged particles are wet by similarly charged oil
droplets, thus the electrostatic repulsive forces are weak relative to other
interactions, such as adsorption or chemisorption of surface active compounds.
The authors stress the ability of certain solids to collect at the oil-water
interface of emulsified droplets and thus inhibit flocculation. However, our
results show that natural sediment assemblages rapidly accommodate large
amounts of oil (see Table 6.4). When natural sediments of smaller particle
size were studied, larger fractions of the sediment were retained in a sur-
face film (Table 6.5).
66
-------
These studies and many other more specialized reports not included here
graphically point to our fundamental lack of understanding concerning the
behavior of oil toward natural suspended solids. Further work should stress
the specific interactions of components of oil toward natural materials and
the mechanics of the adsorption and flocculation processes. Special emphasis
is needed on the presence of surfactants in the oil, in the DOC, or in
organic matter associated with the solid phases.
6.6 SUMMARY
Laboratory studies were performed to investigate the amounts of oil that
might be accommodated by suspended matter from the Skagit and Fraser Rivers.
Experiments were conducted in sea water (S = 32°/oo) at 10° and 15°C with
varying amounts of Prudhoe Bay crude oil (9-133 mgj added to 50 mg of sedi-
ment. These sediment concentrations are unrealistically high, except for
the river estuaries, but represented levels that are analytically tractable
and at the same time provide insight into the accommodation levels that
might be achieved under ideal conditions.
Skagit River suspended sediments, with a median diameter of 2.6 ym, were
the most efficient scavengers of crude oil. At the highest loading of oil
attempted (L = 2.7 mg oil added/mg sediment added), the loading of accommo-
dated oil was near 1 mg oil/mg sediment, and decreased linearly as the amount
of oil was systematically decreased. Increasing the temperature to 15°C re-
sulted in a marked decrease in the amount of oil coprecipitated with the sedi-
ment particles. Highest loadings observed at 15°C were 15% of the sediment
weight, down from 30% at 10°C.
Fraser River sediments were finer-grained (d j- =1.6 ym) and mineral -
ogically distinct from the Skagit River suspended sediments. The proportion
of clay minerals was higher in the former sediments relative to the latter.
The highest loading observed was 17%, in the absence of dissolved organic
carbon (T = 10°C), but was more typically 5-10%. The differences between the
amounts of oil recovered from the different sediment types are provisionally
assigned to differences in particle size and mineralogy. Associated organics
may have played a role, but we were not able to assess their significance at
this time.
Oil spilled onto the surface of the ocean is immediately affected by
several physical, chemical, and biological processes. One of them is the
coating of suspended particles and their subsequent suspension in the water
column or transport to the bottom where benthic detrital feeders may assimi-
late them. Our experiments have shown that locally-derived riverine sediments
possess the capacity to accommodate up to their own weight in oil under con-
trolled laboratory conditions. What is desired ultimately, however, is an
evaluation of the kinetic factors responsible for the coflocculation of oil
and suspended matter under natural environmental conditions, such as waves,
wind, and suspended matter concentrations. At the same time, a better under-
standing of the specific interactions between particles of diverse composition
and equally complex oil is desired.
67
-------
7. NATURAL DISTRIBUTIONS OF HYDROCARBONS
ON SUSPENDED MATTER
7.1 GENERAL STATEMENT
The occurrence and distribution of petroleum hydrocarbons adsorbed to
suspended matter have not been extensively investigated, although there are
numerous inferences to the importance of particulate matter in the adsorp-
tion and subsequent transport of hydrophobic pollutants (see section 6.1).
An excellent review of the literature on this topic is contained in an
article by Clark and MacLeod (1977) and a report by the National Academy of
Science (1975).
In a very recent study by Van Vleet and Quinn (1977), the importance of
suspended solids in the transport of petroleum hydrocarbons discharged from
a waste treatment plant was emphasized. Their study showed that approximately
95% of the hydrocarbons discharged were in the particulate form, the remainder
as solubles. Because fulvic and humic materials are known to incorporate
hydrocarbons, either through interlatice absorption or surface adsorption
(Ogner and Schnitzer, 1970), the aforementioned authors found that only 2Q%
of the suspended hydrocarbons were associated with these fractions.
The Strait of Juan de Fuca, San Juan Island passages, and the Strait of
Georgia represent contiguous commercial waterways over which significant
quantities of petroleum and refined products are transported. Puget Sound
and, in particular, the San Juan Archipelago represent major recreational
areas, enjoyed by many small boat enthusiasts. Moreover, these waters are
in direct communication with the major ports of Washington and British
Columbia and, consequently, receive discharged waste materials and pollutants.
Sources of pollutants include transfer operations, wastewater discharge,
spillage (accidental or otherwise), and riverine input.
Because of the likely sources of petroleum and related materials in the
waters of Northern Puget Sound, a complementary study was formulated to in-
vestigate the character of hydrocarbons associated with suspended matter and
thus elucidate their probable origin. This section focuses on the seasonal
distribution of hydrocarbons adsorbed to suspended matter, compositional
characteristics, and probable sources.
Suspended matter consists of both living and dead material. It is pri-
marily composed of inorganic detrital mineral phases derived from river and
stream runoff; terrestrial plant material; living planktonic organisms,
including phytoplankton, zooplankton, and bacteria; and marine organic detri-
tus such as fecal matter and the tests of dead organisms. These components
are largely natural in origin and are supplemented by a wide compositional
range of particles of anthropogenic origin. Some of these would include
plastics, wood fibers, styrofoam, inorganic particles arising from industrial
activities, and weathered petroleum residues (i.e., tar balls). Tar balls
are a rather common artifact in waters used as major transportation routes
and their occurrence in the Strait of Juan de Fuca would not be unexpected.
68
-------
7.2 FIELD STUDIES
In an attempt to ascertain the distribution and abundance of adsorbed
petroleum-related hydrocarbons, four stations were strategically located
near probable or anomalous source areas; the fifth station, near Port Angeles
(sta. 9) was chosen for control. The station near Admiralty Inlet (sta. 35)
was occupied in order to characterize material derived from Puget Sound.
Stations were also located near Deception Pass (sta. 15), Cherry Point
(sta. 17), and the southern arm of the Fraser River (sta. 26) in order to
characterize possible inputs from these sources. Waters passing through
Deception Pass carry a portion of the suspended load derived from the Skagit
River. Although this river is not heavily industrialized, modest levels of
agriculture are carried out in the lower aluvial basin of the river. Cherry
Point and nearby Ferndale are the loci of major oil refineries in Washington,
and thus, represent sites for probable oil input. Lastly, the station near
the Fraser River estuary was selected to assess hydrocarbon levels associated
with a major industrialized river complex, although substantial agriculture
also is carried out in the lower river basin.
Attempts were made to occupy each of these stations seasonally, although
weather was sometimes a factor. This was particularly true for stations 9
and 35, located in the westerly fetch of the Strait of Juan de Fuca.
Station 31A, occupied only once in Harrow Strait (MESA-I), was abandoned
because of its close proximity- to major shipping lanes and intense tidal
currents which hampered anchoring of the vessel. In place of this location,
station 35 in the eastern Strait of Juan de Fuca was chosen as an alternate
(see above).
Suspended matter was retrieved from preselected depths at each station,
depending on the location of the near-surface suspended matter concentration
maximum. This was determined every four hours with a continuous profiling
nephelometer (see section 5) and the depth of the pump head adjusted accord-
ingly. The suspended material was pumped from depth and passed through a
SorvallR SS-3 continuous flow centrifuge in a manner described earlier (see
section 6.3.4).
7.3 METHODOLOGY
7.3.1 Sample Collection
Suspended matter was sedimented in a continuous flow centrifuge operated
at approximately 15,000 r.p.m. or 30,000 G's. Flow rate was maintained be-
tween 400 and 500 m£ min'1- Filtration of the effluent through 0.4 ym
NucleporeR membrane filters indicated that more than 90% of the mass of the
material greater than 0.4 ym was recovered during centrifugation. As
described earlier (section 6.3.4), small organic particles are probably lost
due to their low specific gravity.
The centrifuge was operated continuously for the sampling period, except
in the case of mechanical failure. Prior to actual sample collection, water
was pumped (12 gal min'1) through the hose and prefiltration manifold for one
69
-------
hour to reduce contamination arising from the pump, hose, manifold, and
tubing.
Suspended matter was collected in eight stainless steel centrifuge tubes
which, prior to use, were cleaned in methylene chloride and hexane. All cen-
trifuge parts in contact with the sample were cleaned in a similar fashion.
At the termination of sampling, the contents of the sampling tubes were
quantitatively transferred to precleaned jars fitted with an aluminum-foil
lined cap. The sample was immediately frozen at -20 C until analysis.
7.3.2 Sample Preparation and Analysis
The sample, usually between 1 and 5 g dry weight, was placed in a 50 ma
centrifuge tube and the hydrocarbons extracted according to the original pro-
cedure of MacLeod et al. (1976). In this procedure, a 35% methyl alcohol/
methylene chloride mixture was used instead of diethyl ether to extract the
lipid fraction. Extractions were carried out on a tumbler at room tempera-
ture for 18 hours, solvent decanted, and the extraction repeated for an addi-
tional 18 hours. The extracts were combined and the remaining sediment dried
and weighed. Aliphatic and aromatic fractions were separated on silica gel
as described in the aforementioned reference.
The component analyses of the aliphatic and arene fractions were
carried out on wall-coated glass capillary columns (30 m x 0.25 mm i.d.)
treated with SE-30. The 6.C. analysis of the aromatic hydrocarbons was per-
formed by NNAF under the supervision of Dr. William MacLeod. Also, both
alkane and aromatic standards were provided to us by NNAF- Component compo-
sition of the aliphatic and aromatic standards is shown in Table 7.1 with
typical chromatograms of the alkane standard (ALK-9) and the arene standard
(PAH-6) presented in Figures 7.1a,b. Reagent and procedural blanks were
determined for all runs.
The concentration of each component in the mixture is calculated from
its response factor as determined from daily calibration and normalized to
the response of the internal standard, hexamethylbenzene. Component identi-
fication is based on retention indices, again normalized to the internal
standard.
Replicate injections of standards show component precision to be no
better than ± 20%. However, errors associated with extraction efficiencies
due to matrix effects may be much larger (Rohrbach and Reed, 1975). We have
not performed an intercomparison of various extraction techniques on sus-
pended matter, although because of its large compositional variability,
matrix effects could be severe.
70
-------
Table 7.1 Component listing and concentrations for aliphatic standard
(ALK-9) and arene standard (PAH-6)
Alkane Standard
Component
C12
Cis
Cut
Hexamethyl-
benzene
Cis
Cie
Cl7
Pristane
Cis
Phytane
1-C1-C16
C19
C20
C21
C22
&23
C2«*
C25
C26
C27
C28
C29
C30
Csi
C32
(ALK-9)
Cone.
ng/yJi
15.6
10.3
11.3
9.8
10.4
30.0
11.1
10.2
9.5
8.8
11.6
10.4
14.6
10.4
10.3
10.6
9.9
21.4
10.4
10.5
10.6
10.2
10.0
10.8
9.9
Arene Standard (PAH-6)
Component
Indane
1,2,3,4-Tetramethybenzene (TMB)
Naphthalene (NPH)
Benzothiophene (BTP)
2-Methyl naphthalene (2MN)
1-Methyl naphthalene (1MN)
Trtisopropyl benzene (TPB)
Biphenyl (BPH)
2, 6-Dimethyl naphthalene (DMN)
Hexamethyl benzene (I.S.)
2, 3, 5-Trimethyl naphthalene (TMN)
Fluorene (FLU)
Dibenzothiothiophene (DBT)
Phenanthrene (PHN)
Anthracene (ANT)
1-Methyl phenanthrene (MPH)
Fluoranthene (FLA)
Pyrene (PYR)
Benz[a]anthracene (BAA)
Chrysene (CHR)
Benz[e]pyrene (BEP)
Benz[a]pyrene (BAP)
Perylene (PER)
Cone.
ng/yji
11.1
10.6
10.3
12.8
13.1
12.1
9.0
13.8
11.0
10.1
10.0
10.5
14.8
11.1
9.4
10.2
11.8
9.9
12.4
9.5
10.0
12.1
10.2
71
-------
16 20
25
a
IS
2 14
1?
V
)
V
1MB
,
18
Pr
17
l f
C
I
Ph
1'
9
2, 2
2 23 24
26
L.
27
L»-_
28
ud--
29
k^.^
30
' - - ~
3
32
JL
Q a.< 3E b. 0.
± i- mo x H
Q.Q.OC
IU
-------
7.4 RESULTS
7.4.1 Field Sampling
A summary of the suspended matter samples collected for hydrocarbon
analysis during the three MESA cruises is presented in Table 7.2. Of the
five stations originally scheduled, one station was lost during each cruise.
With the exception of station 26 during the MESA-II cruise, all others were
lost due to inclement weather. During MESA-III, the normal time series at
station 9 was moved into Freshwater Bay (sta. 10B), west of Port Angeles,
because of poor sea conditions (see Fig. 5.1).
It is readily apparent from Table 7.2 that on the average only small
amounts of suspended material were recovered in most instances. The low
recovery of sediment resulted in reduced sensitivity; in fact, some chroma-
tograms were not distinguishable from the solvent and procedural blanks. A
case in point was station 10B, occupied during MESA-III, in which only .08 g
of material was obtained (Table 7.2). Time spent on each station varied
from 17 hours to 24 hours, resulting in 282 a to over 700 £ of water passed
through the centrifuge.
7.4.2 Suspended Hydrocarbons - MESA I
Four time series stations were successfully occupied during this cruise
as depicted in Table 7.2. Station 9, located in the central strait, was not
occupied because of high winds and seas. Dry weight recoveries of suspended
material ranged from 0.90 g to 4.69 g, the latter amount recovered from
station 26 near the mouth of the Fraser River.
Extractable hydrocarbons recovered from all the samples acquired during
this cruise reflected unusual, but similar compositional patterns, not ob-
served on subsequent cruises. All samples taken during this cruise were
recovered and extracted in the same fashion as were other samples, except
they were freeze dried. Subsequent check of our freeze drier indicated no
interference at the levels suggested in the gas chromatograms.
Rather than treat each station individually, since the results may be a
sampling or an analytical artifact, we will discuss the results obtained at
station 15 as representative and for the sake of completeness.
The chromatographic signature of the aliphatic fraction is shown in
Figure 7.2. The dominant characteristic of the chromatogram is the presence
of an unresolved complex mixture centered near heneicosane, extending from
C17 to C2i*. Specific characteristics of the UCM include a slight dominance
of odd-numbered n-alkanes, pristane/phytane ratio near 0.5, and a heptadecane/
pristane ratio of 1.2. The most abundant straight chain paraffins, tenta-
tively identified on the basis of retention times, were nonadecane and
heneicosane, although isoprenoid hydrocarbons of similar carbon length also
are likely candidates. Identification of individual contributions to the
UCM was not undertaken, but it was suggested that the UCM may be composed of
unsaturated hydrocarbons, presumably biological in origin (personal communi-
cation, Dr. D. Brown, NNAF).
73
-------
TABLE 7.2 Sampling protocol for suspended hydrocarbons at each of the time
series stations. Volume of water is the quantity passing through
the centrifuge as determined by a cumulative flow meter. Amount
of material recovered is expressed in grams dry weight.
MESA- I
Date
Time on Station, hours
Nominal Pump Depth, meters
Volume of Water, liters
Amount of Material , grams
9 15
N.S.1 11/18/77
17.5
8
568
2.26
Stations
17 26
11/19/77 11/21/76
20.0 17.5
25 2.5
600 525
0.90 4.69
31A
11/22/76
23.6
3
708
1.65
MESA- I I
Date
Time on Station, hours
Nominal Pump Depth, meters
Volume of Water, liters
Amount of Material , grams
9 15
3/11/77 3/12/77
22.5 22.5
18 18
673 693
0.47 1.00
Stations
17 26
3/14/77 N.S.1
22.0
18
741
1.24
35
3/15/77
22.0
10
690
0.67
MESA-III
Date
Time on Station, hours
Nominal Pump Depth, meters
Volume of Water, liters
Amount of Material , grams
10B 15
8/9/77 8/10/77
18.5 17.3
10 10
282 349
.08 0.49
Stations
17 26
8/11/17 8/13/77
21 17.8
12 15
478 511
1.27 1.79
35
N.S.i
1No sample taken.
74
-------
21
01
Figure 7.2 Gas chromatogram of the saturated hydrocarbon fraction from station 15.
The numbers reflect the chain length of the normal alkanes.
-------
A GC analysis of the aromatic fraction revealed few major compounds;
none were identifiable on the basis of retention indices. A UCM was present,
but not as large as that observed in the saturate fraction. When compared to
standards, the bulk of the components were characterized by retention indices
similar to that of 3- and 4-ring aromatics.
Without further corroborating evidence, these observations do not
clearly identify the source of the hydrocarbons. However, several composi-
tional features are evident. The abundance of n-alkanes in the carbon range
Ci7-C2i+, modest odd-even dominance of normal paraffins, and the apparent pres-
ence of olefinic hydrocarbons, all suggest the hydrocarbons are of biogenic
origin (Clark and Brown, 1977). Subsequent discussions with Dr. T. Reed of
UCLA suggested that the complexity of compounds observed in this rather small
carbon range indicate bacterial metabolism of the organic matter. While this
may be a viable explanation, it remains unclear why samples from this cruise
only show the unusual hydrocarbon pattern. The absence of paraffinic com-
pounds in the range of C2i-C32 indicates no significant input from either
plant waxes or weathered petroleum residues.
7.4.3 Suspended Hydrocarbons - MESA II
Stations occupied and amounts of suspended material recovered during the
spring cruise are reflected in Table 7.3. Quantities of suspended matter re-
trieved were generally small, ranging from 0.47 g to 1.24 d dry weight.
The quantity of hydrocarbons recovered varied widely, depending on loca-
tion and probable sources (Table 7.3). Hydrocarbon concentration was greatest
at station 9 (nearly 790 yg/g) and a minimum at station 17 near Cherry Point
(approximately 170 yg/g). Amounts of hydrocarbons obtained do not correlate
with suspended matter concentrations, but appear to be regionally dependent.
With the exception of station 15, the concentrations of saturates and unsatu-
rates were nearly equal (Table 7.3).
Chromatographic analysis of the aliphatic fraction obtained from
station 9 is shown in Figure 7.3a and the concentrations of individual nor-
mal alkanes are indicated in Table 7.4. Significant concentrations of nor-
mal paraffins were observed in the C2? to C32 range and may represent
weathered petroleum residues or possibly terrestrial plant waxes. With the
exception of pentadecane, no significant contribution of hydrocarbons from
plankton were observed.
Minimum detection limits for individual hydrocarbons are indicated by
concentration "less than" and were computed on the basis of sample blanks
and quantity of sediment recovered. The average response factor for the nor-
mal alkanes (Ci2-C32) only decreases about 10% over the range; thus the
minimum detection limits shown in Table 7.4 have been computed on the basis
of a mean response factor, corrected for daily variation using the internal
standard hexamethylbenzene.
As shown in both Figure 7.3a and Table 7.4, the most abundant alkanes
were in the carbon range C25 to C32. The most abundant paraffin was hentrla-
contane; its concentration was approximately 2 yg/g. Inspection of Table 7.4
76
-------
TABLE 7.3 Concentrations of saturated and unsaturated
hydrocarbons at stations sampled.
Cruise v'
Citation
MESA I
9
15
17
26
31A
MESA II
9
15
17
26
35
MESA III
10B.
15
17
26
35
Sample
Weight
(9)
-
1.13
0.90
4.69
1.65 ,
0.47
1.00
1.24
-
0.67
.08
0.49
1.27
1.79
-
Saturates
(vg/g)
-
1858
4556
541
5289
356
233
75
-
164
900
178
42
236
-
Unsaturates
(ug/g)
-
371
764
96
752
453
87
99
-
198
510
307
161
82
-
77
-------
IS
ITPr
27 28
31
32
JL
o
lA
10
IH.
10
00
&
o
(A
m
c
o.
o
c
"5
a.
o
E
5
n
c
.*
o
Q.
O
C
K
?
O <
c
4)
0>
0)
L.
C
O
(0
CM
>s
Q.
0)
c
w
o
n
Q>
O S
>s
IP Q.
6 S
0)
CO
O
o
o
u
Figure 7.3 Gas chromatograms of the (a) saturated and (b) unsaturated fraction from station 9
located near Port Angeles (MESA-II). Normal alkanes are indicated by carbon chain
length; peaks labeled "C" are known contaminants. Retention time windows of
typical arenes are shown for reference purposes.
-------
TABLE 7.4 Concentrations of normal alkanes and the isoprenoid hydrocarbons
pristane and phytane at stations occupied during MESA-II.
Normal Alkanes
Cl2
Cn
Cis
Cie
Cl7
Pristane
Cl8
Phytane
C19
^20
C2i
C22
^23
C25
C26
C27
^28 -
C2g
c30
C3i
C32
Station 9
< 50
i -
1104
< 50
< 50
95
< 50
1 r
57
< 50
! -
66
128
123
298
808
1842
1860
2017
1215
Station 15
(ng/g dry
< 26
i •
159
< 26
53
28
< 26
\
41
< 26
! '
235
110
190
< 26
Station 17
weight)
< 18
T 1
104
< 18
] '
25
< 18
48
25
57
33
59
110
317
282
359
144
Station 35
< 28
V
127
< 28
< 28
82
< 28
< 28
32
36
175
160
306
378
456
412
292
238
413
274
400
< 28
79
-------
reveals a slight odd-even preference in the above carbon range, but probably
is not significant. We would interpret the character of the hydrocarbons to
imply weathered petroleum or related products such as tar balls. Given the
transportation activity in the Strait of Juan de Fuca, it is likely that tar
balls would have been sampled along with the normal suspended detritus. By
way of comparison, a much stronger odd-even preference is shown at the other
stations sampled (Table 7.4), implying that a much larger fraction of the
hydrocarbons obtained at these stations were derived from plant waxes (Ogner
and Schnitzer, 1970).
We have also compared these results with those of MacLeod et al. (1976)
taken from both contaminated and uncontaminated beach sediments near Port
Angeles. The abundance of individual alkanes observed at station 9 are
rather similar to the levels observed in contaminated intertidal sediments,
but the most abundant alkane was C31 rather than C2? noted in the previous
reference. Also, the contaminated sediments were characterized by normal
paraffins generally found in the kerosene and light oil fraction of petroleum
(Clark and Brown, 1977) and a large UCM centered near C28- Neither of these
features were present in the suspended matter analysis, but the quantity of
sediment extracted was only 0.47 g, compared to 100 g of intertidal sediments
analyzed (MacLeod et al., 1976).
The relatively high concentration of normal alkanes, characteristic of
the heavy distillate oil fraction, may be due to the inclusion of tar balls.
If this is so, then the reporting basis of the individual hydrocarbon shown
in Table 7.4 is incorrect.
The unsaturated fraction is shown in Figure 7.3b. None of the major
peaks were identifiable on the basis of retention indices; however, represen-
tative compounds are shown for reference purposes. The identity of the major
peak occurring at 43.50 min. is unknown, but by comparative analogy with ex-
tracts of copepods and other zooplankton (Shaw, 1977), we would tentatively
identify the compound as 3,6,9,12,15,18-heneicosahexaene (HEH), a polyolefin.
This compound is also the most dominant hydrocarbon in 18 species of phyto-
plankton studied (Blummer et al., 1971), thus its occurrence in a sample
containing plankton is not unexpected. We stress that this assignment is
primarily based on its ubiquity in planktonic organisms and on Its relative
retention indices. It occurred in the aromatic fraction of all samples.
Mass spectral analysis is needed to establish the structure of this compound.
The peaks labeled "C" are contaminants, probably alkanes, and are believed to
have leached out of the caps of the storage vials. They were observed in a
few samples and also in several standards, but were not present in the proce-
dural blanks.
A chromatographic trace of the aliphatic fraction from station 17 is
shown in Figure 7.4a and the concentrations of the normal paraffins are given
in Table 7.4. Of the biological hydrocarbons, only pentadecane (C15) was
significantly above the background levels. Its concentration was approximately
160 ng/g. Heptadecane and pristane, the isoprenoid Ci7 hydrocarbon, were also
present in concentrations near the background levels. The most abundant paraf-
fins present were nonacosane, triacontane and hentriaeontane (029-63!), not
unlike that observed at the other stations sampled (Table 7.4). However, their
80
-------
oo
a
C M2425262.7 28 ^ 'O 31
15 17 Dh I 20 21 22 iYi i, JMVJL- 1 A, Ai ,
- u-JL^ . 4. L! Lj^-JL-^—VMW •<'^fc-f^-nu '" * / - -it
«
• t
«
b : s i ,s
S * 9 g •
e _
of
a
o
Z
n
~ S * o
5 * S •> t •
* ^ a. c * c
* g- o £ c S
0.0 C i. 5 £
0 — ">» £ ^ *
5 • 1 g ?
5 Q (t Q. ^
2
N
1
C
e *
a. °
r-» m
o c
u
IkJVu. -/, ., \.A-HL.LjJLj
»
n
C
I
U
a.
V
«
m
Figure 7.4 Gas chromatograms of the (a) saturated and (b) unsaturated fractions from station 17
located near Cherry Point (MESA-II). Normal alkanes are indicated by carbon chain
length; peaks labeled "C" are known contaminants. Retention time windows of typical
arenes are shown for reference purposes.
-------
concentrations were approximately a factor of 10 less and indicated a much
stronger odd-even preference. Both nonacosane (C29) and triacontane (C31)
were present at concentrations near 200 ng/g.
The chromatogram of the aromatic fraction from station 17 is shown in
Figure 7.4b. It was not unlike that obtained at station 9 with the exception
of the major peak at retention indices 54.17 min. We assume that this is
another biogenic component, but it is unclassified at this time. A UCM was
observed in this chromatogram, part of which may be the result of contamina-
tion. No evidence of fresh petroleum was found in the aliphatic fraction,
although the high molecular weight aromatics associated with oil may be more
resistant to degradation.
7.4.4 Suspended Hydrocarbons - MESA III
Stations occupied and amounts of suspended material recovered during the
summer cruise are presented in Table 7.2. Amounts of suspended material were
generally small, reflecting the continuing drought conditions which accented
the normally small runoff at this season of the year (see section 2). At
station 10B, in Freshwater Bay, only 80 mg of material was recovered, although
the concentrations of the saturates and unsaturates were relatively large
(900 and 510 yg/g, respectively). As expected the largest quantity of sus-
pended sediment recovered was from station 26, near the mouth of the Fraser
River. However, the concentration of hydrocarbon was rather typical (see
Table 7.3). Rather than discuss each station in detail, we will, as before,
select stations 17 and 26 as representative, although the pertinent composi-
tional data for the other stations will be shown in Tables 7.3 and 7.5.
The saturated hydrocarbon composition of suspended matter collected at
station 17 is depicted in Figure 7.5a and Table 7.5. The most abundant hydro-
carbons present were pentadecane (582 ng/g) and pristane (2069 ng/g) with
lesser amounts of heptadecane and nonadecane. These particular components are
most certainly of biological origin (Blumer et al., 1971), presumably derived
from plankton. With the exception of a small amount of heptacosane (C2?)> the
remaining normal paraffins were near or below the minimum detection level of
30 ng/g.
A chromatographic analysis of the aromatic fraction is shown in
Figure 7.5b. It is somewhat more complex than those shown previously but
does reflect the major peak at retention indices 43.55 min. In addition, a
suit of compounds is observed between retention indices 37-40 min., which
falls between the retention indices of anthracene and methyphenanthrene.
The identity of these compounds is unknown, but may represent biologically-
derived olefinic hydrocarbons. Their source is most likely marine (i.e.,
plankton) rather than terrestrial because of the location of the station.
There is also a remote possibility that the unsaturated compounds are of
terrestrial origin, possibly suspended matter from the Fraser River, but it
seems to us that marine organic matter would be dominant at this time of the
year.
The absence of a complex aromatic spectra (e.g., alky! naphthalenes;
Hites and Biemann, 1972) and the absence of a smooth alkane envelope between
82
-------
IS IS
U ,"
c
a 20
i 21
-A-+
n
n
Ki
(g
oo
CO
|
I
2 c
-------
TABLE 7.5 Concentrations of normal alkanes and the isoprenoid hydrocarbons
pristane and phytane at stations occupied during MESA-III.
Normal Alkanes
Cj2
Cl3
Cm
Cis
Cie
Cl7
Pr
CIB
Ph
Cl9
C2o
C21
C22
C23
C2lt
C25
C26
C27
C28
C29
C3o
Csi
£32
Station 10A
< 248
\
i
3183
< 248
i
r
851
< 248
< 248
544
< 248
i
i
< 248
Station
(ng/g
< 43
\ '
282
< 43
243
556
68
< 43
i '
68
86
202
499
508
756
553
15 Station 17
dry weight)
< 30
i
I
582
< 30
152
2069
< 30
< 30
76
< 30
i
95
< 30
i
(
< 30
Station 26
< 10
< 10
47
3897
58
257
911
64
221
1032
88
144
209
386
536
703
736
752
486
383
164
141
< 10
84
-------
C15-C?6 (Farrington and Quinn, 1973) would suggest minimal hydrocarbon
contribution from petroleum or related products.
The suspended hydrocarbon composition of the n-alkane fraction taken at
station 26 is shown in Figure 7.6a. Individual compound concentrations are
presented in Table 7.5. Several interesting features are present in the
chromatogram (e.g., Figure 7.6a), including an abundance of odd carbon hydro-
carbons in the range C15 to C20 and a smooth carbon envelope between C21 and
C30. The abundance of peaks between pristane and nonadecane are presumably
planktonically derived hydrocarbons, including isoprenoids and phytadienes.
As we have observed before (e.g., station 10B, Table 7.5), pentadecane was
the most abundant hydrocarbon in the lighter fraction (carbon no. < 21). In
a related study of the hydrocarbon composition of select species of phyto-
plankton, Blumer et al. (1971) found 3,6,9,12,15,18-heneicosahexaene (C21:6)
the predominant hydrocarbon produced by marine phytoplankton with lesser
amounts of the normal alkanes in the range C12 to C25. The dominant normal
alkanes were pentadecane, heptadecane, and heneicosane, with the latter two
compounds more universally present in the species studied. The assemblage
of compounds between octadecane and eicosane presumably represents saturated
and unsaturated isoprenoids derived from zooplankton (Blumer et al., 1971).
The heavier alkanes present in the sample show a uniform envelope
beginning at heneicosane and ending at triacontane. The most abundant normal
paraffins in the suite are pentacosane (C25), hexacosane (C26), and hepta-
cosane (C27); their concentrations are in excess of 700 ng/g. There is no
odd-even preference. The origin of these hydrocarbons is not known, but the
chromatographic pattern is similar to those observed for lubricating oils
(Farrington and Quinn, 1973). Similar patterns have been observed in the
Charles River, Boston (Hites and Biemann, 1972) and in recent bottom sedi-
ments obtained near the Fields Point waste treatment plant located on the
Providence River (Van Vleet and Quinn, 1977). It has also been suggested
that terrestrial plant material may contribute normal alkanes in the carbon
range, although the odd-even preference is usually present (Ogner and
Schnitzer, 1970). The ratio of odd carbon to even carbon in the range C22 to
C32 is 1.11, nearly the same as that found by the above authors. Because
the Fraser River is obviously supplying terrigenous plant material to the
estuary and also is likely to be impacted by petroleum spillage, wastewater
and industrial effluents as it passes through the metropolitan area of
Vancouver, it seems likely that the source of hydrocarbons characterized in
Figure 7.6a is not unequivocal. Additional studies are warranted to
unravel the composition of suspended hydrocarbons in the Fraser River and to
pinpoint their sources.
The aromatic fraction is depicted in Figure 7.6b. The large peak near
fluoranthrene (RT = 43.50 min) is again evident together with a similar
cluster of peaks between retention indices 37.50 and 40.0 min. The grouping
and clustering of these compounds suggest that they are related genetically
and are probably biological in origin. Because this particular sample
appears to have both terrestrial and marine biogenic hydrocarbons (see
Figure 7.6a), the origin of these hydrocarbons is not precisely definable.
Within the above definition of biogenic hydrocarbons, we also include hydro-
carbons resulting from microbial metabolism of organic detritus.
85
-------
15
Pr
17
18
CPh
19
2526
24
23
22
21
,+W
27
28
29
U
30 31
f
8
n
M
u
s?
n
^
Figure 7.6 Gas chromatograms of the (a) saturated and (b) unsaturated
fractions from station 26 located near the mouth of the
Fraser River (MESA-III). Normal alkanes are indicated by
carbon chain length; peaks labeled "C" are known contaminants.
Retention time windows of typical arenes are shown for
reference purposes.
86
-------
The myriad of small, poorly defined peaks shown in Figure 7.6b represent
aromatics and olefins present in the sample. Procedural blanks did not show
the complexity of compounds evident in Figure 7.6b. The origin of these com-
pounds is unknown, but conceivably could represent a low level input from
petroleum or related products. Without further characterization, however,
the origin of these compounds cannot be defined. The absence of a well-
defined UCM does not suggest necessarily that petroleum hydrocarbons were
absent. Analysis of the unsaturate fraction of Prudhoe Bay crude oil, using
glass capillary columns, also did not reveal a UCM that might otherwise have
been observed if packed columns had been used.
7.5 DISCUSSION
The purpose of this portion of the study was to evaluate the present
levels of particulate hydrocarbons in northern Puget Sound and to character-
ize them compositionally. Five stations were identified for seasonal obser-
vations on the basis of current or future probable impact by petroleum.
Since it has been shown that locally derived riverine sediments possess the
capacity to accommodate crude oil (see section 6) and that this material sub-
sequently may be used as a food source by detrital, suspension, and benthic
feeders, it is important that an assessment of suspended hydrocarbons be
conducted.
Based on this rather preliminary assessment, we would conclude that, at
present, suspended matter in the eastern Strait of Juan de Fuca, San Juan
Island passages, and the southern Strait of Georgia is minimally impacted by
petroleum hydrocarbons. Recent studies conducted in Narragansett Bay and the
Providence River estuary show both the suspended matter and the receiving
bottom sediments to be contaminated by petroleum hydrocarbons, presumably
arising from wastewater treatment facilities (Farrington and Quinn, 1973;
Van Vleet and Quinn, 1977; Schultz and Quinn, 1977). Depending on the loca-
tion in the estuary, the total hydrocarbon concentration ranged from 24 mg/g
dry weight material to minimum values less than 1 mg/g dry weight material.
The upper values are believed to be the result of effluent loading, whereas
the smaller values are more representative of the relatively uncontaminated
lower estuary (Schultz and Quinn, 1977). The highest values measured in this
work were from stations 17 and 31 (MESA-I), where concentrations in excess of
6 mg/g dry weight were observed (Table 7.3). However, as previously stated,
these data are suspect, and more typical values are 1 mg/g dry weight or less
(Table 7.3).
In the previous studies cited above, chromatographic analysis of the
alkane fraction derived from both suspended matter and bottom sediments
showed a strong UCM centered near C26. No such pattern was observed in any
of our samples with the possible exception of station 26 (MESA-III). This
may be an analytical artifact because we used glass capillary columns or
because the HC component loadings were too small to result in peak overlap,
or both Suspended matter samples taken in the Strait of Juan de Fuca (sta-
tion 9 and station 35, MESA-II) did show the possible presence of weathered
petroleum residues (i.e., tar balls), but this remains speculation at this
time (see Table 7.4).
87
-------
We have also compared our results with the findings of an Intertidal
sediment study carried out by MacLeod et al. (1976) in the Port Angeles harbor
and Dungeness Bay. The former area was known to be contaminated by petroleum;
the latter was considered pristine. The concentration of total HC (saturated
plus unsaturated) at the harbor intertidal site ranged from 1.5 mg/g dry
weight to less than 0.2 mg/g dry weight, whereas the site in Dungeness Bay
was characterized by HC concentrations uniformly less than .05 mg/g dry
weight. Thus, the relative difference is important, not the absolute concen-
tration. Although not reported, the intertidal beach sediments are presumably
lower in carbon than the suspended matter in the overlying water. Thus, on a
weight basis, it would be expected that the concentration of biogenic hydro-
carbons would be greater in the suspended matter. Compositionally, the alkane
fraction chromatograms we obtained at all study sites more nearly resemble
those obtained by MacLeod et al. (1976) for the Dungeness Bay sediments (i.e.,
clean) as compared to the complex hydrocarbon composition observed for Port
Angeles Harbor.
We also attempted to compare the hydrocarbon distributions and patterns
obtained in this study with the comprehensive work currently being conducted
by Dr. Shaw of IMS, Alaska on the Alaskan OCS. However, differences in
methdology and the myriad of environments present in the nearshore areas of
Alaska have prevented a direct comparison. Also, Dr. Shaw has not performed
a systematic study of HC associated with suspended matter, but rather has
focused his research efforts on biota and intertidal sediments. In general,
the concentrations of aliphatics and aromatics in nearshore and intertidal
sediments was less than 30 yg/g wet weight sediment (Shaw, 1977). Although
the composition and abundance of the hydrocarbons are related to the organic
carbon concentration, which was not given, the aforementioned hydrocarbon
concentrations are considerably lower than that observed in Dungeness Bay by
MacLeod et al. (1976). This is not surprising in view of the small input
levels of natural hydrocarbons (e.g., lower primary productivity) and the
equally small anthropogenic contribution.
In Table 7.6 is shown the ratio of hydrocarbons to particulate organic
carbon. It is readily apparent that the hydrocarbons represent no more than
3% of the total organic carbon (station 15, MESA-III), but more typically
less than 1%. A study of the HC/OC ratio in sediments derived from the
Providence River estuary showed this ratio to vary longitudinally down the
estuary (.07 to .02) as well as vertically in the sediment column (Van Vleet
and Quinn, 1977). At their station 4, located most distant from the Fields
Point waste treatment facility, the HC/OC ratio decreased from .024 at the
surface (0-10 cm) to .0014 at depth (30-40 cm). These figures are in rather
close agreement with the data shown in Table 7.6 and would suggest that con-
tamination of suspended matter by petroleum hydrocarbons 1s minimal.
The relatively high organic carbon content of the suspended matter and
the low C/N ratio both suggest that the carbon is of marine origin (Banse,
1974). This contention would support our findings that the major Identifiable
hydrocarbons in the alkane fraction below C2i are biogenic 1n origin, presum-
ably arising from phytoplankton and zooplankton. Above C2i the normal paraf-
fins are either the result of petroleum residues or plant waxes, or a mixture
-------
TABLE 7.6 Summary of hydrocarbon concentrations, organic carbon, carbon:
nitrogen ratios, and the ratio of extractable hydrocarbons to
organic carbon at selected stations.
Station
15
9
17
17
26
Hydrocarbon Conc.a Organic Carbon
mg/g %
MESA- I
2.2 8.2
MESA- I I
0.79 6.9
0.17 3.3
MESA-III
0.20 9.1
0.32 3.4
C/NC HC/OC
8.4 .026
6.7 .01
8.8 .005
8.1 .002
7.0 .009
aTotal concentration of saturated and unsaturated hydrocarbons taken
from Table 7.3.
bPercent organic carbon as dry weight.
C0rganic carbon:nitrogen weight ratio.
89
-------
thereof. Based on these few preliminary results, it is not possible to
establish levels of petroleum hydrocarbons associated with suspended matter.
7.6 SUMMARY
During 1976 and 1977, a seasonal investigation was initiated to evaluate
the ambient levels of suspended hydrocarbons with special emphasis on hydro-
carbons of petroleum origin. For this work, five strategic locations were
examined in the eastern Strait of Juan de Fuca, San Juan Island passages, and
the southern Strait of Georgia. Sampling sites included the entrance to
Puget Sound (Admiralty Inlet), Deception Pass, Cherry Point, the mouth of the
Fraser River, and a central point in the Strait of Juan de Fuca near Port
Angeles. Suspended matter was recovered with a continuous flow centrifuge
and extracted for total hydrocarbons.
Of the samples taken, only gas chromatographic analysis of hydrocarbon
extracts showed a predominance of biological compounds (e.g., pentadecane,
heptadecane, pristane, etc.), including higher molecular weight alkanes
believed to be of plant origin. In two samples, the presence of petroleum
hydrocarbons was implied, not conclusively shown. Suspended matter taken
from the Strait of Juan de Fuca was characteristically high in normal paraf-
fins in the carbon range C25-C32» which may be plant waxes or weathered
petroleum residues. The dominant alkane was hentriacontane (C31); its concen-
tration approximately 2 pg/g dry weight sediment.
Material collected from the mouth of the Fraser River contained abundant
amounts of both biological hydrocarbons and a heavier fraction that chromato-
graphically appears to be similar to motor oil (C22-C32)- In this range, the
most abundant normal paraffin was pentacosane (0.7 yg/g dry weight). Again,
this particular fraction of the aliphatic hydrocarbons may represent a con-
tribution from plant waxes.
The total amount of extractable hydrocarbons varied from 0.2 mg/g dry
weight to 1.4 mg/g dry weight. These concentrations fall between those
observed in pristine Alaskan shelf sediments and those observed in the
Providence River-Narragansett Bay estuary system. On the basis of these few
data and the limited sample size (0.5-5 g dry weight), we were not able to
unequivocally define the presence of petroleum hydrocarbons, although a few
samples were suggestive. Larger suspended matter samples are required with
attention given to definitive marker compounds in both the aliphatic and
aromatic fractions. Systematic studies of point sources would be highly
beneficial in defining the fate of oil in natural systems as well as their
characterization as a function of time and space.
90
-------
8. LANDSAT IMAGERY
8.1 INTRODUCTION
It is evident from the discussions in the previous sections of this
report that suspended sediments, originating from the Fraser and Skagit
Rivers, can play a major role in the dispersal and deposition of some frac-
tions of petroleum that may be released as a result of oil transportation
through the Strait of Georgia-Strait of Juan de Fuca system. Consequently,
a comprehensive understanding of the dispersal mechanisms and trajectories
of suspended sediments from these rivers is essential to any model which
attempts to predict the fates and potential impacts of oil in these waters.
The suspended matter distribution studies, which have been described else-
where in this report and represent the first comprehensive survey of its
kind in the study region, provide useful data on the seasonal variations of
particulate distributions. However, due to the physical limitations of
operating from a single vessel the data are not entirely synoptic and must
be integrated over several tidal cycles. In order to obtain truly synoptic
information other forms of data must be obtained.
In recent years several advances in remote sensing techniques have pro-
vided scientists with the ability to collect synoptic information about water
circulation and sediment dispersal patterns which heretofore have been unob-
tainable. The multispectral scanner images from the LANDSAT-1 and LANDSAT-2
satellites have been especially useful for the study of suspended matter
transport processes in coastal and estuarine waters (Kritkos et al., 1974;
Klemas et al., 1974; Gatto, 1976; and Johnson et al., 1977).
Table 8.1 shows the major characteristics of the LANDSAT satellites and
multispectral scanner. The multispectral scanner has four spectral bands.
The green band (0.5-0.6 pm) and the red band (0.6-0.7 urn) provide information
about the dispersal patterns of suspended matter from major source regions
such as rivers, streams, and coastal outfalls. The far red band (0.7-0.8 urn)
only shows the core of the sediment plume and the near infrared band (0.8-
1.1 urn) shows the shoreline. The data from the multispectral scanner is
transmitted to a receiving station and then is converted to a photographic
product.
In order to provide synoptic information about variations of suspended
sediment distributions, water trajectories, and tidal mixing patterns, all
usable LANDJAT imagery from 1972 to the present were collected and correlated
with corresponding data on water and sediment discharge (U.S. Geological
Survey and Water Survey of Canada), water circulation 'appropriate published
literature as cited), tides and tidal currents (Tide Tables, National Ocean
Survey), and suspended sediment distributions (this report). LANDSAT MSS
bands 4 and 5 were found to be ideal for studying the dispersal of turbid
water. The sediment plumes, which appear lighter in tone than les: turbid
water in the images, are natural tracers of the low salinity water tha+
exists offshore from the Fraser and Skagit estuaries. However, the LANDb.n
imagery only provides information about the upper few meters of the water
column. Fortunately, previous studies have shown that the brackish water is
91
-------
TABLE 8.1 Principal characteristics of the LANDSAT satellite and
multispectral scanner
System Parameters
Specific Specifications
Satellite
Altitude
Type of Orbit
Orbits per Day
Coverage Cycle
Time of Observation
Size of Area Imaged
Field of View
Side Lap
Overlap Along Orbit
Multispectral Scanner
Image Distortion
Ground Resolution
Position Accuracy
Spectral Bands, Bandwidths (\m),
and Nominal Color
915 km
circular, sun synchronous
14
18 days
approx. 1000 a.m. at 50 north latitude
185 x 185 km
11.56°
67%
10%
2%
80 to 120 meters
900 meters
4: 0.5-0.6; green
5: 0.6-0.7; red
6: 0.7-0.8; far red
7: 0.8-1.1; near infrared
92
-------
generally confined to the upper 5 meters or less (Waldichuk, 1957; Tabata,
1972; and Schumacher et al.t 1978), and therefore, the LANOSAT imagery can be
used to study the migration patterns of the low salinity water provided the
sediment loading is sufficiently higher than the surrounding water.
8.2 SEASONAL VARIATIONS
The amount of useful information about seasonal variations of suspended
sediment distributions and dispersal patterns that can be obtained from
LANDSAT imagery is somewhat limited because most cloud-free days occur during
the summer; and, as a result, the majority of available images are from that
season. However, two high quality images* from January 1973 (Figs. 8.1 and
8.2) and one from March 1976 (Fig. 8.3) are available. Therefore, some gen-
eral statements about sediment dispersal patterns for winter, spring, and
summer can be made.
When the fresh water and sediment discharge from the Fraser River are
high, particularly during the spring floods and during the ebbing tide, the
longitudinal pressure head at the river mouth produces a well-defined turbid
plume which extends outward into the Stait of Georgia. The orientation of the
plume axis can be used to determine the direction of flow. During the months
of May through August, the southward flow of Main Arm and Middle Arm is so
strong that the resultant plume maintains its identity for a considerable dis-
tance and, in some cases, traverses the entire length of the Strait.
Figures 8.4, 8.6, and 8.9 are examples of this phenomenon. Depending upon
local changes in tidal currents, the plumes extend either to the southeast or
southwest from the river mouth. Tidal mixing is rapid and numerous eddies
are apparent.
At the mouths of Middle Arm and North Arm there was some evidence of flow
to the northwest in most of the images. This feature is particularly evident
in Figures 8.6 and 8.7. These plumes appear to maintain their identity as far
north as Point Grey and the entrance to Burrard Inlet.
The Skagit River plume flows into Skagit Bay and Saratoga Passage during
the summer months (Figs. 8.4 thru 8.9). Some plume material passes through
Deception Pass into Rosario Strait during ebb tide (Fig. 8.8).
The winter plumes from the Fraser and Skagit Rivers, as shown in the
LANDSAT images from January 1973 and March 1976 (Figs. 8.1 thru 8.3), are much
less distinct than that observed during summer. For instance, the Fraser
River plumes in January and March are only visible in the nearshore regions
just a few kilometers seaward of the river mouth, where the primary flow pat-
tern is to the southeast. During this period, the discharge of both water and
suspended sediments are at a minimum. Average discharge rates for water and
*Specific characteristics of the images are uniquely identified in the
figures by numbered markers and are described both in the text and in the
figure captions.
93
-------
Fig. 8.1 MSS Band 5 of LANDSAT image 1169-18373 on Jan. 8, 1973 between
slack water and minor ebb current. Time of image acquisition
was 1037 PST. The image shows little evidence of sediment dis-
persal from the Fraser River into the Strait of Georgia, reflect-
ing the lower water and sediment discharge during the winter
season. The image is free of cloud cover.
TIDAL CURRENT:
Slack
Water
0906
Max.
Current
0515
1209
Vel.
(kts)
1.7
1.7
TIDES:
Time
High
Low
at
at
0834
1429
Ht
2.
1.
.(m)
9
6
94
-------
Fig. 8.2 MSS Band 5 of LANDSAT image 1187-18374 on Jan. 26, 1973. Time of
image acquisition was 1037 PST, between slack water and major ebb
current. The image shows limited dispersal of suspended sediments
into the Strait of Georgia from the Fraser River.
TIDAL CURRENT:
Slack
Water
0508
1008
Max.
Current
0733
1501
Vel.
(kts)
0.9
2.3
TIDES:
Time
High at 0905
Low at 1811
Ht.(m)
2.6
0.4
95
-------
Fig. 8.3 MSS Band 4 of LANDSAT image 2417-18220 on Mar. 14, 1976. Time of
image acquisition was 1022 PST, between minor ebb current and
slack water. The image shows limited dispersal of suspended sedi-
ments into the nearshore waters south and southeast of the mouths
of Main, Middle and North Arms.
TIDAL CURRENT:
Slack
Water
0454
1150
Max.
Current
0806
1322
Vel.
(kts)
1.8
0.8
TIDES:
Time
Low at 0808
High at 1402
Ht.(m)
0.8
1.9
96
-------
Fig. 8.4 MSS Band 5 of LANDSAT image 2111-18254 showing a southeasterly
dispersal (1) of suspended sediments from the Fraser River into
the Strait of Georgia on May 13, 1975. Time of image acquisition
was 1025 PST, between major ebb current and slack water. The
dispersal pattern shows movement of Fraser River sediments into
Haro Strait, primarily through Boundary Pass. Sediment discharge
from the Skagit River into Skagit Bay and Saratoga Passage is
evident (2). 10 cloud cover is observed in the lower right
corner of image.
TIDAL CURRENT:
Slack
Water
0506
1404
Max.
Current
1000
1643
Vel.
(kts)
2.9
2.4
TIDES:
Time
High at
Low at
0449
1246
Ht.(m)
2.4
-0.5
97
-------
Fig. 8.5 MSS Band 5 of LANDSAT image 2129-18254 showing a southwesterly
dispersal of suspended sediments from the Fraser River into the
Strait of Georgia on May 31, 1975. Time of image acquisition
was 1025 PST, just after flood current. An anticyclonic gyre
can be observed due west of Pt. Roberts (3). Sediment discharge
from the Nooksack River can be seen in Bellingham Bay (4). Image
is free of cloud cover.
TIDAL CURRENT:
Slack
Water
Max.
Current
0650
1256
Vel.
(kts)
weak and
variable
1.6
TIDES:
Time
High at 0821
Low at 1522
Ht.(m)
1.7
0.3
98
-------
Fig. 8.6 MSS Band 5 of LANDSAT image 1727-18290 showing a southeasterly
dispersal (5) of suspended sediments from the Fraser River into
the Strait of Georgia on July 20, 1974. Time of image acguisition
was 1029 PST, between major ebb current and slack water. The
dispersal pattern suggests movement of Fraser River sediments
along Saturna, Mayne, and Galiano Islands and into Trincomali
Channel from Porlier Pass. Suspended sediments from the North
Arm appear to flow to the northwest and to the northeast into
• Burrard Inlet (6). A cyclonic eddy (7) can be observed north
of Galiano Island. Sediment discharge from the Skagit River into
Skagit Bay (8), and from the Nooksack River into Bellingham Bay
(9) is clearly visible. Several tidal fronts are also observed
in the Strait of Juan de Fuca.
TIDAL CURRENT:
Slack
Water
0429
1303
Max.
Current
0912
1534
Vel.
(kts)
3.1
2.0
TIDES:
Time
Low at 1147
High at 1904
Ht.(m)
-0.7
2.7
99
-------
Fig. 8.7 MSS Band 5 of LANDSAT image 5465-17484 showing a southeasterly
dispersal (10) of suspended sediments from the Fraser River into
the Strait of Georgia on July 27, 1976. Time of image acquisition
was 1048 PST, between major ebb current and slack water. The
dispersal pattern suggests movement of Fraser River sediments
into Haro Strait from the passages on either side of Mayne and
Saturna Islands (11), and into Rosario Strait from the south-
eastern Strait of Georgia (12). Suspended sediments discharging
into the Strait from North Arm appear to flow northward past Pt.
Grey where it bifurcates, a portion flowing to the northwest,
and the remaining flowing to the northeast into Burrard Inlet (13),
TIDAL CURRENT:
Slack
Water
0408
1224
Max.
Current
0904
1517
Vel.
(kts)
2.7
1.8
TIDES:
Time
High at
Low at
0225
0931
Ht.(m)
1.9
-0.7
100
-------
0 20
I I I I I
KILOMETERS
Fig. 8.8 MSS Band 4 of LANDSAT image 2921-18025 showing southeasterly dis-
persal (14) of suspended sediments from the Fraser River into the
Strait of Georgia on July 31, 1977. Time of image acguisition
was 1002 PST, between major ebb current and slack water. A tidal
front is clearly indicated in the center of the Strait of Georgia
- (15). Suspended sediments can be observed discharging into Skagit
Bay and through Deception Pass into Rosario Strait (16).
TIDAL CURRENT:
Slack
Water
1306
Max.
Current
0921
1531
Vel.
(kts)
3.1
1.8
TIDES:
Time
High at
Low at
0437
1149
Ht.(m)
2.4
-0.4
101
-------
Fig. 8.9 MSS Band 5 of LANDSAT image 2957-18004 showing a southwesterly
dispersal (17) of suspended sediments from the Fraser River into
the Strait of Georgia on Sept. 5, 1977. Time of image acquisition
was 1000 PST, between major flood current and slack water. The
dispersal pattern suggests southwesterly flow associated with the
flood current. Three small cyclonic eddies can be observed north
of Mayne Island (18, 19 and 20). 40" cloud cover is visible over
most land masses.
TIDAL CURRENT:
Slack
Water
1201
Max.
Current
0756
1502
Vel.
(kts)
0.7
0.7
TIDES:
Time
Low at 0414
High at 1227
Ht.(m)
0.4
1.9
102
-------
sediments are approximately 10-30% of the mean annual rates (see Fig. 2.2).
This means that both the longitudinal pressure gradient and the suspended
sediment concentrations are greatly reduced in winter. Consequently, the
forces which drive the Fraser River plume into the Strait of Georgia are
diminished in winter, resulting in more rapid mixing of the plume and concur-
rent dilution of suspended sediment concentrations to background levels.
These conclusions are substantiated by the results of the seasonal surveys of
suspended matter concentrations in the vicinity of the Fraser River which were
presented earlier in this report. The background concentration of suspended
matter in the study region was found to be approximately 1.0 mg/a. Near the
mouth of the Fraser River particulate concentrations ranged between 2.5 and
9.0 mg/«, during the November and August surveys (see, for example, stations 25,
26, and 27 in Figs. 5.4 and 5.6). However, in March the particulate concen-
tration for station 25 was 0.9 mg/i or approximately the same as background
values for this region and time of year, indicating rapid dilution of the
Fraser River plume as it discharges into the Strait.
The Skagit River also shows a minimum in water and sediment discharge
during the winter period (Fig. 2.3). However, the percentage decrease is not
as large as the winter decrease of the Fraser River (the average water and
sediment discharge rates for the Skagit River during the months of January
through March are 50-70% of the mean annual rates); and, as a result, the
seasonal variations of the Skagit River plume are not nearly as pronounced.
The LANDSAT images for January 1973 and March 1976 show evidence for movement
of suspended sediments from the Skagit River into the nearshore regions of
Skagit Bay (Figs. 8.2 and 8.3). This material mixes rapidly with the offshore
water and the plumes do not maintain their identity beyond Deception Pass.
8.3 TIDAL VARIATIONS
As indicated in Table 8.1, the LANDSAT satellites maintain a sunsynchro-
nous orbit around the earth in such a manner as to arrive at the same location
at approximately the same time of day once every 18 days. Because the average
tidal interval is about 12 hours 25 minutes, the tides will be out of phase by
approximately one quarter cycle each time the satellite passes over. This
means that over the course of several years the LANDSAT imagery for a given
location should include all tidal stages if proper atmospheric conditions have
prevailed. Since their deployment in 1972 and 1975, the LANDSAT satellites
have produced approximately eight or nine high quality images which can be
used for describing tidal effects on the dispersion of the Fraser River plume.
Figures 8.3 through 8.9 show examples of LANDSAT imagery which are of
sufficient quality to be useful for studying tidal processes. The ebb tides
are represented by Figures 8.3, 8.4, 8.6, and 8.8 and flood tides are indicated
in Figures 8.5 and 8.9. The tidal stage corresponding to each of the LANDSAT
images has been determined and is included in the figure captions. Patos
Island was used as a reference point for determination of the tidal stage
because: (1) it is centrally located with respect to the northern part of
the study region and, consequently, differences in tidal stages are relatively
small (e.g., the tides at the mouth of Main Arm precede those at Patos Island
by about 2-4 minutes, whereas the tides at Deception Pass precede those at
Patos Island by about 77 minutes); and (2) it provided the most complete set
of data on tides and tide currents.
103
-------
During ebb tide, distinct sediment plumes originating from Main Arm and
Middle Arm flow seaward in a southwesterly direction to a point approximately
midway between Steveston and Porlier Pass where the plumes are diverted in a
southeasterly direction by the ebb flow in the Strait. Figures 8.4, 8.6, and
8.7 are examples of this process. The sediment plumes migrate with the flow
across the Strait and through the passages between Orcas, Saturna, Mayne, and
Galiano Islands into Haro Strait. In one case the tidal flow was so strong
that the sediment plume could be traced as far east as the passage between
Orcas and Lummi Islands (Fig. 8.7). However, the prevailing northwesterly
winds were steady at about 30 mph and may have added to this effect (Pacific
Weather Center, Environment Canada).
Numerous cyclonic and anticylonic eddies are associated with the plumes.
These eddies, which are probably the result of interactions between inertial,
tidal, and coriolis forces, maintain their integrity for several hours. For
instance, in Figure 8.6, a cyclonic eddy is observed in the region north of
Galiano Island. Since it appears to be detached from the major plume emanat-
ing from the Fraser River, it probably represents a relict bolus that moved
into the region during a previous tide. This means that at least during some
seasons, boluses of low salinity water derived from the Fraser River are
probably capable of maintaining their identity for periods longer than a
single tidal cycle.
The sediment plume emanating from North Arm during ebb tide flows to the
north and west past Point Grey (Figs. 8.6 and 8.7). Beyond Point Grey the
plume bifurcates, with a portion of the plume moving to the northwest and the
remaining material flowing to the northeast into Burrard Inlet.
The dispersal pattern of the Fraser River plume during flood tide has
some characteristics which are very similar to the pattern for ebb tide and
some which are uniquely different. As indicated in Figures 8.5 and 8.9, the
sediment plumes originating from Main Arm and Middle Arm flow seaward in a
southwesterly direction. However, instead of being diverted to the southeast,
as is the case during ebb tide, the flood current drives the sediment plume
across the Strait and to the northwest along the northern coast of Galiano
Island. Some material from the plume passes into Trincomall Channel from
Porlier Pass and the remaining material continues to flow to the northwest,
mixing with and being diluted by the less turbid water of the northwestern
Strait.
There is evidence for some small cyclonic and anticyclonic eddies in the
plumes associated with the flooding tide. These eddies are interpreted as
evidence for interactions between the longitudinal pressure gradient, asso-
ciated with the fresh water input from the Fraser River, and the tidal and
coriolis forces associated with water movement in the Strait during flood
tide (Tabata, 1972). It is interesting to note that the anticyclonic eddies
in the LANDSAT images are most pronounced when the tidal and coriolis forces
are additive. The large anticyclonic eddy due west of Point Roberts in
Figure 8.5 is an example of this situation. The plume appears to be split
into two parts, presumably by tidal and coriolis forces. These processes
increase the rate of lateral mixing and subsequent dilution of the plume.
104
-------
The sediment-laden plume from North Arm flows to the north around Point
Grey and into Burrard Inlet during flood tide. There is no evidence from the
LANDSAT images of sediment movement to the northwest during this stage of the
ti de.
8.4 SUMMARY AND CONCLUSIONS
LANDSAT images, obtained during the period between 1972 and 1977, have
been utilized to study the surface trajectories of sediment plumes originating
from the Fraser and Skagit Rivers. These plumes are natural tracers of flow
patterns of low salinity water and suspended matter that is discharged into
northern Puget Sound from these rivers.
Three separate plumes can be observed emanating from the distributaries
of the Fraser River. The plumes from Main Arm and Middle Arm join together
to form a well-defined jet which can be traced across the Strait of Georgia
and through Porlier, Active, and Boundary Passes. During ebb tide the plume
is directed to the southeast from a point about midway between Steveston and
Porlier Pass. The flood tide drives the plume across the Strait and to the
northwest along the northern coast of Galiano Island. The presence of a
well-defined jet is indicative of the significance of the longitudinal pres-
sure and inertia! forces. When water and sediment discharge is high, parti-
cularly during the spring runoff period, these forces predominate and the
plumes maintain their identity for considerable distances. When discharge is
low these forces are weak and'tidal, coriolis, and wind forces predominate,
causing rapid mixing and corresponding dilution of the plumes. The plume
from North Arm moves to the northwest past Point Grey where it bifurcates,
with some material flowing to the northwest during ebb tide and the remaining
material moving into Burrard Inlet. The northward flow of the plume from the
North Arm is probably the result of a combination of a number of forces in-
cluding inertial, pressure, and coriolis.
The existence of a number of separate plumes in some of the images
suggests that eddies of sediment-laden water are probably capable of maintain-
ing their identity for periods longer than a single cycle. This implies that
a dynamic balance exists between the inertial and pressure forces associated
with these boluses and the coriolis and tidal forces associated with circula-
tion patterns in the Strait. From observations of photographs taken near the
mouth of Main Arm, Tabata (1972) suggests that this balance is maintained by
the daily surge of fresh water from the river merging with the already present
low salinity water lying along the southwestern side of the Strait. Our data
support these conclusions, at least for the periods of high runoff. While the
winter data are very limited, there is no evidence for multiple plumes, indi-
cating that mixing is rapid and the lifetimes of the plumes are very short,
probably less than one tidal cycle.
The plumes from the distributaries of the Skagit River are most pro-
nounced in early summer, during the peak runoff. During this period suspended
sediments from the Skagit River can be traced as far south as the middle of
Saratoga Passage and as far north as Deception Pass, where Skagit River
105
-------
sediments flow into Rosario Strait during ebb tide. During the period of low
discharge, the Skagit River plume is confined to the nearshore regions of
Skagit Bay.
In conclusion, the salient features of the dispersal patterns and trajec-
tories of suspended sediments from the Fraser and Skagit Rivers have been
examined using LANDSAT imagery. A number of conclusions about the character-
istics of the circulation patterns and suspended sediment distributions have
been inferred from the images which cannot be verified until extensive sea-
borne observations are initiated. In the future, attempts should be made to
augment the LANDSAT observations with corresponding sea truth data collected
in a synoptic manner.
106
-------
ACKNOWLEDGMENTS
We wish to express our sincere gratitude to Dr. W. Macleod, Dr. D. Brown,
and to S. Ramos of the NOAA Analytical Facility for their technical and analy-
tical support of the hydrocarbon program.
The authors also express appreciation to M. Lamb for the preparation of
the LANDSAT images and for the compilation of the hydrological data; to G.
Massoth for his help in data reduction and analyses; and to J. Nevins for the
analysis of suspended matter mineralogies. Special appreciation is extended
to S. Hamilton, A. Chapdelaine, and C. Katz for their assistance in hydrocar-
bon analysis, scanning electron microscopy, and graphics.
This work was supported by the Office of Energy, Minerals, and Industry,
Office of Research and Development, U.S. Environmental Protection Agency
through an interagency agreement with the Environmental Research Laboratories
of NOAA.
107
-------
BIBLIOGRAPHY
Atkinson, L. P., and F. A. Richards. 1967. The Occurrence and Distribution
of CH4 in the Marine Environment. Deep-Sea Res. 14:673-686.
Baier, R. E. 1970. Surface Quality Assessment of Natural Bodies of Water.
Proc. Conf. Great Lakes Res. 13:114-127.
Banse, K. 1974. On the Interpretation of Data for the Carbon to Nitrogen
Ratio of Phytoplankton. Limnol. Oceanogr. 19:695-699.
Bassin, N. J., and T. Ichiye. 1977. Flocculation Behavior of Suspended
Sediments and Oil Emulsions. J. Sed. Petrol. 47:671-677.
Blumer, M. 1971. Scientific Aspects of the Oil Spill Problem. Environ.
Affairs. 1:54-73.
Blumer, M., R.R.L. Guillard, and T. Chase. 1971. Hydrocarbons of Marine
Phytoplankton. Mar. Biol. 8:183-189.
Broecker, W. S., and T. H. Peng. 1974. Gas Exchange Rates Between Air and
Sea. Tell us. 29:21-35.
Brooks, J. M. 1977. The Flux of Light Hydrocarbons into the Gulf of Mexico
via Runoff. In: Marine Pollutant Transfer, pp. 185-200, H. L. Windom
and R. A. Duce, eds. Lexington Books, D. C. Heath Co., Lexington,
Mass. 391 pp.
Brooks, J. M., A. D. Fredericks, W. M. Sackett, and J. W. Swinnerton. 1973.
Baseline Concentrations of Light Hydrocarbons in Gulf of Mexico.
Environ. Sci. Technol. 7:639-642.
Brooks, J. M., and W. M. Sackett. 1973. Sources, Sinks and Concentrations
of Light Hydrocarbons in the Gulf of Mexico. J. Geophys. Res. 78:5248-
5258.
Brooks, J. M., and W. M. Sackett. 1976. Significance of Low-molecular-
weight Hydrocarbons in Marine Waters. In: Proc. 7th International
Meeting Organic Geochemistry, pp. 455-468.
Castellan, G. W. 1964. Physical Chemistry. Addison-Wesley Publishing Co.,
Reading, Mass. 717 pp.
Chang, P., S. Pond, and S. Tabata. 1976. Subsurface Currents in the Strait
of Georgia, West of Sturgeon Bank. J. Fish. Res. Bd. Can. 33:2218-2241.
108
-------
Chipman, W. A., and P. S. Galtsoff. 1949. Effects of Oil Mixed with
Carbonized Sand on Aquatic Animals. U.S. Dept. Inter. Spec. Sci. Rept.,
Fisheries No. 1. 49 pp.
Clark, R. C., and D. W. Brown. 1977. Petroleum: Properties and Analyses
in Biotic and Abiotic Systems. In: Effects of Petroleum on Arctic and
Subarctic Marine Environments and Organisms, Vol. I, pp. 1-90. D. C.
Mai ins, ed. Academic Press, Inc., New York. 321 pp.
Clark, R. C., and W. D. MacLeod. 1977. Inputs, Transport Mechanism, and
Observed Concentrations of Petroleum in the Marine Environment. In:
Effects of Petroleum on Arctic and Subarctic Marine Environments and
Organisms, Vol. I, pp. 91-224. D. C. Malins, ed. Academic Press,
New York. 321 pp.
Cline, J. D. 1977. Identification of Natural and Anthropogenic Petroleum
Sources Utilizing Low Molecular Weight Hydrocarbons, C^Ci,. OCSEAP/ERL
Quarterly Rept. 153, June-Sept., Boulder, Colo.
Cline, J. D., and M. L. Holmes. 1977. Submarine Seepage of Natural Gas in
Norton Sound, Alaska. Sci. 198:1149-1153.
Conover, R. J. 1971. Some Relations Between Zooplankton and Bunker C. Oil
in Chedabucto Bay Following the Wreck of the Tanker "Arrow." J. Fish.
Res. Bd. Can. 28:1327-1330.
EPA. 1977. Review of Environmental Issues of the Transportation of Alaskan
North Slope Crude Oil, EPA-600/7-77-046. Office of Energy, Minerals and
Industry, Office of Research and Development, EPA, Washington, D.C.
123 pp.
Farrington, J., and J. G. Quinn. 1973. Petroleum Hydrocarbons in
Narragansett Bay, Part I: Survey of Hydrocarbons in Sediments and
Clams, Mercenaria mercenaria. Estuarine Coast. Mar. Sci. 1:71-79.
Farrington, J. W., and J. G. Quinn. 1973. Petroleum Hydrocarbons and Fatty
Acids in Wastewater Effluents. J. Water Pollut. Contr. Fed. 45:704-
712.
Forrester, W. D. 1971. Distribution of Suspended Particles Following the
Wreck of the Tanker "Arrow." J. Mar. Res. 29:151-170.
Gatto, L. W. 1976. Circulation and Sediment Distribution in Cook Inlet,
Alaska. In: Assessment of Arctic Marine Environment Selected Types.
pp. 205-228. D. W. Hood and D. C. Burrell, eds. Occasional Pub. No. 4,
Univ. Alaska, Fairbanks, Alaska.
Geyer, R. A., and W. M. Sweet, Jr. 1973. Natural Hydrocarbon Seepage in the
Gulf of Mexico. Trans. Gulf Coast Ass. Geol. Soc. 23:158-169.
Gordon, D. C., and P. D. Keizer. 1974. Hydrocarbon Concentrations in Sea-
water along the Halifax-Bermuda Section: Lessons Learned Regarding
109
-------
Sampling and Some Results. In: Marine Pollution Monitoring (Petroleum).
Natl. Bur. Stand. Spec. Publ. 409. pp. 113-115.
Hartung, R., and G. W. Klinger. 1968. Sedimentation of Floating Oil.
Michigan Acad. Sci. Art. Lett. 53:23-27.
Herlinveaux, R. H., and J. P. Tully. 1961. Some Oceanographic Features of
Juan de Fuca Strait. J. Fish. Res. Bd. Can. 18:1027-1071.
Hites, R. A., and K. Biemann. 1972. Water Pollution: Organic Compounds in
the Charles River, Boston. Sci. 178:158-160.
Huang, C. P., and H. A. Elliott. 1977. The Stability of Emulsified Crude
Oils as Affected by Suspended Particles. In: Fate and Effects of
Petroleum Hydrocarbons in Marine Organisms and Ecosystems, pp. 413-420.
D. A. Wolfe, ed. Pergamon Press, New York. 478 pp.
Jeffrey, L. M., and D. W. Hood. 1958. Organic Matter in Seawater: An
Evaluation of Various Methods of Isolation. J. Mar. Res. 17:247-271.
Johnson, R. W., I. W. Duedall, R. W. Glasgow, and J. R. Proni. 1977.
Quantitative Mapping of Suspended Solids in Wastewater Sludge Plumes in
the New York Bight Apex. J. Water Poll. Contr. Fed. 49:2063-2073.
Klemas, V., D. Bartlett, W. Phil pot, R. Rogers, and L. Reed. 1974. Coastal
and Estuarine Studies with ERTS-1 and SKYLAB. Remote Sensing of
Environ. 3:153-174.
Kolpack, R. L. 1971. Biological and Oceanographical Survey of Santa Barbara
Channel Oil Spill, 1969-1970. Vol. II. Physical, Chemical, Geological
Studies. Allen Handcock Foundation, Univ. Southern Calif.
Kreider, R. E. 1971. Identification of Oil Leaks and Spills. In: Proc.
Joint Conf. Prev. Contr. of Oil Spills, pp. 119-124. Amer. Petrol.
Inst., Washington, D.C.
Kritokos, H., L. Yorinks, and H. Smith. 1974. Suspended Solids Analysis
Using ERTS-A Data. Remote Sensing of Environ. 3:69-75.
Lamontagne, R. A., J. W. Swinnerton, V. J. Linnenbom, and W. D. Smith. 1973.
Methane Concentrations in Various Marine Environments. J. Geophys. Res.
78:5317-5324.
Lamontagne, R. A., J. W. Swinnerton, and V. J. Linnenbom. 1974. Ci-C4 Hydro-
carbons in the North and South Pacific. Tellus. 26:71-77.
Link, W. K. 1952. Significance of Oil and Gas Seeps in World Oil Exploration.
Amer. Ass. Petrol. Geol., Bull. 36:1055-1540.
McAuliffe, C. D. 1966. Solubility in Water of Paraffin, Cycloparaffin,
Olefin, Acetylene, Cycloolefin, and Aromatic Hydrocarbons. J. Phys. Chem.
70:1267-1275.
110
-------
McAuliffe, C. 1969. Solubility in Water of Normal C9 and C10 Alkane Hydro-
carbons. Sci. 158:478-479.
McAuliffe, C. D. 1977. Dispersal and Alteration of Oil Discharged on a
Water Surface. In: Fate and Effects of Petroleum Hydrocarbons in
Marine Organisms and Ecosystems, pp. 19-35. D. A. Wolfe, ed.
Pergamon Press, Elmsford, New York. 478 pp.
MacLeod, W. D., D. W. Brown, R. 6. Jenkins, L. S. Ramos, and V. D. Henry.
1976. A Pilot Study on the Design of Petroleum Hydrocarbon Baseline
Investigation for Northern Puget Sound and Strait of Juan de Fuca.
NOAA Tech. Memo. ERL MESA-8, NTIS, Springfield, Virginia. 53 pp.
Meyers, P. A., and J. G. Quinn. 1973. Factors Affecting the Association of
Fatty Acids with Mineral Particles in Seawater. Geochim. Cosmochim.
Acta. 37:1745-1759.
NAS. 1975. Petroleum in the Marine Environment, E. G. Wilson, ed. National
Academy of Science, Washington, D.C. 107 pp.
Ogner, 6., and M. Schnitzer. 1970. The Occurrence of Alkanes in Fulvic Acid,
a Soil Humic Fraction. Geochim. Cosmochim. Acta. 34:921-928.
Pacific Northwest River Basins Commission. Puget Sound Task Force. March
1970. Comprehensive Study of Water and Related Land Resources, Puget
Sound and Adjacent Water's, State of Washington, Appendix III, Hydrology
and Natural Environment.
Parker, B. 1977. Tidal Hydrodynamics in the Strait of Juan de Fuca-Strait
of Georgia. NOAA Tech. Rept. NOS-69, NOAA/DOC, Washington, D.C. 56 pp.
Parker, C. A. 1970. The Ultimate Fate of Crude Oil at Sea—Uptake of Oil by
Zooplankton. AML Rept. B. 198 pp.
Poirier, 0. A., and G. A. Thiel. 1941. Deposition of Free Oil by Sediments
Settling in Sea Water. Bull. Am. Assoc. Petrol. Geol. 25:2170-2180.
Reeburgh, W. S., and D. T. Heggie. 1977. Microbial Methane Consumption
Reactions and Their Effect on Methane Distributions in Freshwater and
Marine Environments. Limnol. Oceanogr. 22:1-9.
Rohrback, B. G., and W. E. Reed. 1975. Evaluation of Extraction Techniques
for Hydrocarbons in Marine Sediments. Inst. Geophys. Planet. Physics.
Publ. No. 1537. University of California, Los Angeles.
Sackett, W. M. 1977. Use of Hydrocarbon Sniffing in Offshore Exploration.
J. Geochem. Explor. 7:243-254.
Schultz, D. M., and J. G. Quinn. 1977. Suspended Material in Narragansett
Bay: Fatty Acid and Hydrocarbon Composition. Organic Geochem. 1:27-36.
Ill
-------
Scranton, M. I., and J. W. Farrington. 1977. Methane Production in the
Waters Off Wai vis Bay. J. Geophys. Res. 82:4947-4953.
Sharp, J. H. 1974. Improved Analysis for "Particulate" Organic Carbon and
Nitrogen from Seawater. Limnol. Oceanogr. 19:984-989.
Shaw, D. 1977. Hydrocarbons: Natural Distribution and Dynamics on the
Alaskan Outer Continental Shelf. In: Environmental Assessment of
Alaskan Continental Shelf, Vol. XIII, pp. 507-727. U.S. Dept. of
Commerce/11.S. Dept. of Interior, OCSEAP, Boulder, Colo. 857 pp.
Schumacher, J. D., C. A. Pearson, R. A. Charnell, and N. P. Laird. 1978 (in
press). Regional Response to Forcing in Southern Strait of Georgia.
Estuar. Coast. Mar. Sci.
Smith, H. M. 1968. Qualitative and Quantitative Aspects of Crude Oil
Composition. Bur. Mines, Bull. 642. U.S. Dept. Interior, U.S. Govern-
ment Printing Office, Washington, D.C. 136 pp.
Sternberg, R. W., E. T. Baker, D. A. McManus, S. Smith, and D. R. Morrison.
1974. An Integrating Nephelometer for Measuring Particle Mass Concen-
trations in the Deep Sea. Deep-Sea Res. 21:887-892.
Swinnerton, J. W., and V. J. Linnenbom. 1967. Determination of Ci~Ck
Hydrocarbons in Seawater by Gas Chromatogr. 5:570-573.
Tabata, S. 1972. The Movement of Fraser River Influenced Surface Water in
the Strait of Georgia as Deduced from a Series of Aerial Photographs.
Dept. Environ. Water Management, Service Mar. Sci. Branch, Pac. Regional
Pac. Mar. Sci., Rept. 72-6. 69 pp.
Tully, J. P. 1942. Surface Non-tidal Currents in the Approaches to Juan de
Fuca Strait. J. Fish Res. Bd. Can. No. 83. 169 pp.
Van Olphen, H. 1963. Clay Colloid Chemistry. Interscience Publishers,
New York. 301 pp.
Van Vleet, E. A., and J. G. Quinn. 1977. Input and Fate of Petroleum Hydro-
carbons Entering the Providence River and Upper Narragansett Bay from
Wastewater Effluents. Environ. Sci. Techno!. 11:1086-1092.
Waldichuk, M. 1957. Physical Oceanography of the Strait of Georgia, British
Columbia. J. Fish. Res. Bd. Can. 14:321-486.
Water Resources Data for Washington. 1976. U.S. Dept. Int., Geol. Surv.
Water Resources Division. Tacoma, Washington.
Water Survey of Canada. Sediment Data, Canadian Rivers, Inland Waters
Directorate, Ottawa, Canada, 1967-1976.
Water Survey of Canada. Water Data, Canadian Rivers, Inland Waters Direc-
torate, Ottawa, Canada, 1967-1976.
112
-------
Wilson, D. F., J. W. Swinnerton, and R. A. Lamontagne. 1970. Production of
Carbon Monoxide and Gaseous Hydrocarbons in Seawater: Relation to Dis-
solved Organic Carbon. Sci. 168:1577-1579.
Winter, D. F., K. Banse, and 6. C. Anderson. 1975. The Dynamics of Phyto-
plankton Blooms in Puget Sound, a Fjord in the Northwestern United
States. Mar. Biol. 19:139-176.
113
-------
APPENDIX A
Seasonal Distributions and Abundances of
Low Molecular Weight Aliphatics in the
Waters of Northern Puget Sound
114
-------
A.I INTRODUCTION
The development of petroleum resources in Alaska is likely to result in
the increased transshipment of crude oil and refined products to and from
Washington refineries. As a consequence of this, oil and refined products
are apt to enter the waters of Northern Puget Sound in ever-increasing quan-
tities as import and export volumes increase.
Crude oil contains four broad classes of compounds: straight chain and
branched alkanes, cycloparaffins, aromatics, and heterocyclics (Clark and
MacLeod, 1977). Within the paraffin fraction, a wide range of molecular
weights is usually found, depending on the source and maturation history of
the oil. The lightest hydrocarbon found in petroleum, and more abundantly
in natural gas, is methane. Homologs of methane (ethane, propane, butanes,
etc.) are also present, usually in diminishing amounts. During production,
the liquid fraction of petroleum is normally separated from the gas and water
portions, but the separated crude oil still retains significant concentrations
of the light hydrocarbons in solution.
When petroleum is accidentally spilled, several physical, biochemical,
and chemical processes begin to operate immediately to degrade the oil.
Among them are evaporation, solution, photooxidation, emulsification, adsorp-
tion, and biodegradation (NAS, 1975). The most volatile fractions of oil,
including the LMW compounds, are readily volatilized into the atmosphere
(McAuliffe, 1977), but some also go into solution because of their relatively
high solubility (McAuliffe, 1966).
It is presently believed that the most toxic fractions of crude oil are
the low boiling point aliphatics (Blumer, 1971). While the LMW aliphatic hydro-
carbons are of less toxicity than the previously mentioned fractions, they are
soluble, and, therefore, become useful marker compounds for the dissolved or
emulsified fractions of oil.
The occurrence of the LMW aliphatics and aromatics in water may arise
from both natural and anthropogenic sources. Natural marine sources include
microbial production (i.e., marsh gas; Atkinson and Richards, 1967) and
leakage from natural seeps (Link, 1952; Geyer and Sweet, 1973).
Because the low molecular weight hydrocarbons are ubiquitous components
of petroleums (Smith, 1968), and because they are readily monitored, these
compounds have been used commercially (Sackett, 1977) and environmentally
(Brooks and Sackett, 1973) to detect the incipient introduction of petroleum
into marine waters. Documented in numerous reports, scientists from Texas
A&M University have shown the LMWH to be valuable tracers of anthropogenic
petroleum and related products in the Gulf of Mexico via shipping, production,
and transfer operations (Brooks et al., 1973; Brooks and Sackett, 1976;
Brooks, 1977 and references contained therein). Estuaries and shelf waters
along the U.S. coastline have been impacted in particular, as suggested by
the unusually high concentrations of the C2-Ci» homologs of methane (Brooks et
al., 1973).
115
-------
For these reasons as well as the successes that have been achieved in the
coastal waters of Alaska in documenting petroleum sources (Cline and Holmes,
1977), a survey of the waters of the eastern Strait of Juan de Fuca, San Juan
Island Passages, and the southern Strait of Georgia was initiated as a supple-
mentary program. Also, because the LMW aliphatics are proving to be valuable
monitoring parameters, a seasonal assessment of current levels of LMW hydro-
carbon in the waters of northern Puget Sound seemed advisable.
The components measured in this study include dissolved methane, ethane,
ethene, propane, propene, iso- and n-butanes. Only a portion of the results
will be discussed for the purpose of brevity, but the results are typical and
representative. All of the data acquired during the three cruises have been
digitized on punch cards and submitted to NODC/EDS for inclusion in their data
bank.
A.2 METHODOLOGY
The volatile hydrocarbons are removed from sea water according to a
modified procedure of Swinnerton and Linnenbom (1967). Briefly, the proce-
dure is: Hydrocarbons are removed in a stream of ultra-pure He (120-140 ma/
min) and condensed on a single activated alumina trap maintained at -196°C.
Approximately 10 minutes of stripping are required to quantitatively remove
the hydrocarbons (> 98%) from solution, after which time the trap is warmed
to 90-100°C and the absorbed gases are allowed to pass into the gas chromato-
graph (GC).
p
The alkanes are chromatographed on a 60/80 mesh Poropak Q column
(3/16" x 4', stainless steel) at a flow rate of 60 mfc/min and detected sequen-
tially as they emerge from the columns. In order to obtain peak resolution
between the alkanes and alkenes, the Poropak QR column was connected in series
with a short column (3/16" x 2", stainless steel) of activated alumina impreg-
nated with 1% silver nitrate by weight. This modification, coupled with tem-
perature programming from 110-150°C, has resulted in sharper peaks, better
separation and reduced retention times for all components. The GC utilized
was a Hewlett PackardR model 5711, equipped with dual FID's.
The analysis of the samples was conducted in the laboratory rather than
on shipboard. To prevent microbial oxidation of the hydrocarbons, samples
were pickled with 100 mg sodium azide and analyzed within 2 weeks of the
cruise termination.
A.3 RESULTS AND DISCUSSION
A plot of stations sampled for LMW aliphatics is shown in Figure A.I.
These stations were selected as being representative from the complete grid
shown in Figure 5.1. Only the surface distributions of methane (near bottom
also), ethane, and ethene will be presented as little additional information
is gained by considering the entire suite of hydrocarbons observed. If
hydrocarbon pollution was indicated, the concentrations and abundances of C3
and Ci, homologs of methane would be important.
116
-------
STATION GRID
FOR LMWH
MESA 1-3
Figure A.I.
Locations selected for seasonal LMW hydrocarbon observations.
Samples were not taken at every station during each of the
three cruises. This sampling grid represents a subset of
the station sampling protocol shown in Figure 5.1.
117
-------
Seasonal and vertical distributions of LMW aliphatics at selected stations
(2, 5, 15, 17, 23, 26, and 32) are presented in Tables A.I through A.7, for the
purpose of completeness and continuity. The data shown in these tables will
not be discussed in detail as they support the general conclusions presented
below.
A.3.1 LMWH - MESA I
The surface and near bottom distributions of methane are shown in
Figures A.2 and A.3. Surface concentrations in November 1976 varied from
250 n«,/£ (STP) to nearly 800 ni/a (STP); the highest level was observed south
and west of the Fraser River. These concentrations are a factor of 5 to 16
above saturation values (Lamontagne et al.. 1973), which for these water tem-
peratures and salinities (T = 10 C; S = 32 /oo) is approximately 50 r\i/i
(STP) given a methane partial pressure of 1.4 ppmv. A plot of the methane
distribution in the near bottom waters (Figure A.3) shows that methane is
equally high, ranging from a low 345 nih to a high of 849 ni/l. The large
supersaturation of dissolved methane represents a net production of methane
in the water column or from bottom sediments. Methane, or marsh gas, is pro-
duced by microbial fermentation of low molecular weight organic acids or the
direct reduction of C02 (Reeburgh and Heggie, 1977). Because these reactions
are catalyzed by strict anaerobic microorganisms, the bottom sediments are a
likely source. However, because the water column was poorly stratified at
this time of the year and rather strongly tidally-induced vertical mixing was
prevalent, it is unlikely that bottom sediments alone were responsible for
these high concentrations. Based on recent studies by Scranton and Farrington
(1977), it is now believed that significant quantities of methane are produced
within microenvironments. These micrpenvironments are organic particles and
aggregates (e.g., fecal pellets) within which anoxic conditions would prevail.
The concentrations shown here are significantly higher than the shelf
waters of Alaska (Cline, 1977), but rather typical of the shelf waters of
Louisiana and Texas, which are believed to be impacted by petroleum production
and transportation (Brooks and Sackett, 1973). Because Puget Sound is charac-
terized by seasonally high levels of primary production (Winter et al., 1975),
these concentrations, particularly in light of the abundances of the other
hydrocarbons, are not believed to be excessive.
The distributions of ethane and ethene in surface waters are presented in
Figures A.4 and A.5. The range of the concentration of ethane is 0.4 ni/i to
1.0 ni/a (STP) (Figure A.4), whereas ethene varies from 1.6 ni/i to 3.1 ni/l.
These concentrations are rather comparable to those observed in the Alaskan
shelf waters (Cline, 1977) and are what would be expected from normal biologi-
cal activity. Ethene is known to be produced biologically (Lamontagne et al.,
1973) and photochemically (Wilson et al., 1970) in natural sea water, and
these measurements are rather similar to those in other parts of the ocean
(Lamontagne et al., 1974). Also, there is evidence from our extensive studies
in the Alaskan shelf waters that during periods of intense phytoplankton
blooms, ethene is reduced to ethane or ethane 1s produced directly as the re-
sult of high biological activity (Cline, 1977).
118
-------
123*00' W 122*40'
122*20'
METHANE (nl/l)
SURFACE
16-22 NOV. 1976
Figure A.2.
Area! surface distribution of dissolved methane (nt/i, STP)
during 16-22 Nov. 1976 (MESA-I).
119
-------
123*40'
123*20'
METHANE (nl/l)
BOTTOM -5
16-22 NOV. 1976
QAtJ.AQA_ ^ g
Figure A.3. Distribution of dissolved methane (n«./a, STP) within 5 m of
the bottom during 16-22 Nov. 1976 (MESA-I).
120
-------
ETHANE (nl/l)
SURFACE
16-22 NOV. 1976
Figure A.4.
Area! surface distribution of dissolved ethane (nt/t, STP)
during 16-22 Nov. 1976 (MESA-I).
121
-------
ETHENE (nl/l)
SURFACE
16-22 NOV. 1976
Figure A.5.
Areal surface distribution of dissolved ethene (n£/fc, STP)
during 16-22 Nov. 1976 (MESA-I).
122
-------
A.3.2 LMWH - MESA II
The area! distributions and abundances of methane are shown in
Figures A.6 and A.7 for the early spring of 1977. Range of values in the
surface waters was 140 n£/£ to 330 ni/t in the near-bottom waters. These
levels are significantly less than those observed during the previous fall
and suggest a reduced level of biological activity during the observational
period. Supersaturation of methane in the surface layers ranged from 3 to 6.
The surface distribution of ethane during March was nearly the same as
that observed in the previous fall (Figure A.8). Again the range was 0.4 ni/a
to 0.6 n£/£ and suggests little or no input of petroleum containing this com-
pound. Ethene, a hydrocarbon related to marine biological activity, ranged
from 1.0 nsi/s. to 1.5 n£/£, significantly less than the amounts observed during
the previous cruise (Figure A.9). These low levels are rather similar to
those observed in late fall in the Alaskan shelf waters (Cline, 1977) and sug-
gest minimal biological activity.
A.3.3 LMWH - MESA III
The surface and near-bottom distributions of methane for August 1977 are
presented in Figures A.10 and A.11. In the surface layers, the concentration
of methane varied from 120 ni/l to approximately 3600 n£/£ near the Fraser
River. More typical values were in the range 400-600 n£/£, similar to that
observed in fall 1976. The high concentration observed near the Fraser River
may be the result of river input or simply related to high levels of primary
production. In a study of the Houston Ship Canal, Brooks (1977) observed con-
centrations of methane as high as 22,000 n£/£ or a factor of 6 greater than
that observed here. It will be shown below that the anomalously high value
is probably due to increased biological activity.
Near-bottom concentrations (Figure A.11) varied from 365 n£/£ to 970 n£/£,
again near the Fraser River. These again are similar to those concentrations
found in the fall of 1977.
Surface concentrations of ethane were slightly elevated above those
observed in November 1976 and March 1977 (Figure A.12), but again not out of
the normal range observed in known pristine environments (Cline, 1977). The
range of concentrations of ethane was 0.4 n£/£ to 1.5 n£/£, the higher concen-
trations found near Admiralty Inlet, Deception Pass, and Victoria. The
absence of high concentrations of ethane near the Fraser River suggests that
the unusually high concentration of methane observed there was of marine
biological origin.
Figure A.13 shows the surface distribution of ethene. Values ranged
from a low of 2 nJl/d to a high of 20 n£/£ near Admiralty Inlet. These concen-
trations are the highest we have ever measured and represent some of the high-
est concentrations seen anywhere in the oceans (Swinnerton and Lamontagne,
1974). We speculate that these high concentrations are the result of high
biological activity, a high radiant energy flux, and low winds at the time of
the measurements. The first two factors are known to produce ethene (Wilson
et al., 1970); the latter simply retards the flux across the air-sea boundary
(Broecker and Peng, 1974).
123
-------
£ 123*40'
122*20*
METHANE
SURFACE
10-17 MARCH 1977
Figure A.6. Areal surface distribution of dissolved methane (nl/it STP)
during 10-17 Mar. 1977 (MESA-II).
124
-------
I23'00' W 122*40'
METHANE (nl/l)
BOTTOM-5
10-17 MARCH 1977
Figure A.7. Distribution of dissolved methane (|JJ/J. fTP) within 5 m of
the bottom during 10-17 Mar. 1977 (MESA-II).
125
-------
122*40'
122*20*
ETHANE (nl/l)
SURFACE
10-17 MARCH 1977
Figure A.8.
Area! surface distribution of dissolved ethane (nfc/fc, STP)
during 10-17 Mar. 1977 (MESA-II).
126
-------
ETHENE (nl/l)
SURFACE
10-17 MARCH 1977
Figure A.9.
Area! surface distribution of dissolved ethene (ni/t. STP)
during 10-17 Mar. 1977 (MESA-II).
127
-------
£ 123*40'
123*20'
I23'00' W 122* 40'
I22'2tf
METHANE (nl/0
SURFACE
08-14 AUG. 1977
Figure A.10.
Areal surface distribution of dissolved methane (ni/£t STP)
during 8-14 Aug. 1977 (MESA-III).
128
-------
METHANE (nl/l)
BOTTOM-3
08-14 AUG. 1977
Figure A.11. Distribution of dissolved methane (ni/it STP) within 5 m of
the bottom during 8-14 Aug. 1977 (MESA-III).
129
-------
I23-00' W
ETHANE
SURFACE
08-14 AUG. 1977
QAU4B/L.
UNITED STATES
'•.-.ft;:' VICTORIA
.ro
''• '"' AN&LES
Figure A.12.
Area! surface distribution of dissolved ethane (ni/i, STP)
during 8-14 Aug. 1977 (MESA-III).
130
-------
ETHENE (nl/l)
SURFACE
08-14 AUG. 1977
^ 8.8
LrS * £\ * 6-6 .
<&&*
ft- -ir
Figure A.13.
Area! surface distribution of dissolved ethene (ni/Ji, STP)
during 8-14 Aug. 1977 (MESA-III).
131
-------
A useful parameter in which to distinguish natural and petrogenic LMWH is
the ethanerethene ratio (C2:o/C2:i)- Tne success of this ratio depends on the
low abundance of olefinic compounds in petroleum (Clark and MacLeod, 1977) and
the small biological production of the saturated low molecular weight hydrocar-
bons in marine waters (Lamontagne et al., 1974). The surface distribution for
the study site is shown in Figure A. 14. The ratio is uniformly near 0.1, ex-
cept near Admiralty Inlet where it rises to 0.7. Based on our studies of
known petroleum input in Alaskan waters, a ratio greater than one is usually
indicative of a petrogenic input (Cline and Holmes, 1977). The relatively
high ratio near Admiralty Inlet suggests some petrogenic ethane contribution
from Puget Sound, but it is relatively small and within the ambient noise
1 evel .
A. 4 SUMMARY
The low molecular weight aliphatic hydrocarbons were measured seasonally
in the waters of the eastern Strait of Juan de Fuca, San Juan passages, and the
southern Strait of Georgia. This study was conducted as a part of the suspended
matter program and served to delineate the current levels of dissolved methane,
ethane, ethene, propane, propene, iso- and n-butanes. These dissolved consti-
tuents are useful markers of petroleum hydrocarbons.
Methane and ethene, two of the hydrocarbons observed, showed strong
seasonal variations in distribution that could be related to normal seasonal
variations in biological activity. Methane in surface waters range from near
140 nsi/t in March 1977 to a high of 3600 m/i in August of 1977. The mean
concentration for the three observational periods were 480 ± 150 ni/i
(November 1976) and 245 ± 80 nt/i (August 1977); the high and low values
(3600 nfc/fc and 120 ni/i) from the August period were not included in the esti-
mate. Mean surface concentrations were nearly the same in November 1976 and"
August 1977, with a factor of two decrease observed in March 1977.
The concentration of ethene in the surface layers was uniform temporally
and spatially. The mean surface concentrations for November 1976, March 1977,
and August 1977 were 0.6 ± 0.2 nz/£, 0.5 + 0.1 nsL/i, and 0.7 ± 0.4
The mean concentration of ethene in the surface layers was low and uni-
form during the first two observational periods, then increased abruptly in
August of 1977. The mean levels for November 1976 and March 1977 were 2.2 ±
0.6 ni/i and 1.3 ± 0.2 ni/£, respectively, increasing abruptly to 9.6 ± 4.2 n£/A
in August 1977. The cause of this increase is not known, but is believed to be
related to high biological activity and light levels. Both factors are known
to be responsible for the production of ethene.
Based on these few data, much of which was not shown for brevity, it
appears that little hydrocarbon pollution was evident in the waters of northern
Puget Sound. Although incipient levels of petroleum may be present in the sys-
tem, the distributions and abundances of the low molecular weight alkanes and
alkenes are within the normal biological background levels.
132
-------
SURFACE
08-14 AUG. 1977
Figure A.14.
The area! surface ethane/ethene ratio (C2:0/C2:i) during
8-14 Aug. 1977 (MESA-III).
133
-------
TABLE A.I Seasonal distributions of selected hydrocarbons at station 2 (48°11.3'N 122°48.6'W)
MESA I
Nov. 1976
MESA II
March 1977
MESA III
Aug. 1977
Depth S T
(m) (°/oo) (°C)
0
40
0
10
20
50
0 30.47 11.30
10 31.50 10.22
20 31.85 9.66
47 32.49 8.79
Methane
581
548
150
145
137
170
650
605
540
475
Ethane
0.97
0.88
0.39
0.46
0.32
0.45
1.47
0.85
0.68
0.40
Ethene Propane
(n£/a) STP
3.00
2.38
1.16
1.21
0.96
1.01
20.10
7.54
6.05
3.94
1.11
0.93
0.37
0.41
0.22
0.31
1.09
0.63
0.62
0.58
Propene
1.06
0.89
0.65
0.51
0.72
4.63
2.48
2.05
1.42
Ethane/Ethene
0.32
0.37
0.34
0.38
0.33
0.44
.07
0.11
0.11
0.10
-------
TABLE A.2 Seasonal distributions of selected hydrocarbons at station 5 (48°14.0'N 123°17.2'W)
Depth
(«)
0
10
MESA I 9n
Nov. 1976 *u
60
110
0
£ 10
MESA II 20
March 1977 4Q
60
114
0
10
MESA III 20
Aug. 1977 6Q
127
(°/oo)
30.97
31.11
31.16
-
_
-
—
-
-
30.36
30.37
31.11
32.47
33.37
T
(°c)
9.13
9.03
8.97
-
_
-
—
-
-
11.42
11,38
10.65
8.62
7.32
Methane
511
528
531
420
372
185
182
196
202
206
226
503
491
538
473
458
Ethane
0.76
0.83
0.78
0.72
0.95
0.45
0.43
0.48
0.48
0.47
0.58
_
0.75
0.69
0.44
0.28
Ethene
3.06
2.40
2.19
1.30
1.22
1.19
1.25
1.08
1.07
0.97
1.40
7.41
7.79
3.74
1.52
Propane
STP
—
0.67
0.63
0.76
0.32
0.30
0.32
0.32
0.47
0.44
0.54
0.58
0.61
0.42
0.31
Propene
-
1.31
0.64
0.68
0.78
0.76
0.75
0.67
0.55
2.36
2.44
2.35
1.20
0.78
Ethane/Ethene
0.25
0.34
0.36
0.73
0.37
0.36
0.38
0.44
0.44
0.60
-
0.10
0.09
0.12
0.18
-------
TABLE A.3 Seasonal distributions of selected hydrocarbons at station 15 (48°24.2'N 122°41.0'W)
CO
MESA I
Nov. 1976
MESA II
March 1977
MESA III
Aug. 1977
Depth S T
(m) (°/oo) (°C)
8 -
10
20 -
40 -
60
73 -
0 29.72 11.92
10 30.45 10.68
20 30.91 10.16
30 31.29 9.84
40 31.80 9.32
60 32.00 10.24
Methane
474
284
290
278
261
253
584
560
601
676
672
365
Ethane
0.79
0.46
0.46
0.46
0.49
0.49
1.40
0.86
0.86
0.72
0.63
0.45
Ethene Propane Propene
(ni/i) STP
2.07
1.50
1.45
1.38
1.32
1.23
13.30
7.25
7.25
7.44
6.33
4.75
0.63 0.99
0.34 0.83
0.34 0.82
0.32 0.78
0.34 0.71
0.35 0.66
0.97
0.75
0.63
-
0.80
Ethane/Ethene
0.38
0.31
0.32
0.33
0.37
0.40
0.10
0.12
0.12
0.10
0.10
.09
-------
TABLE A.4 Seasonal distributions of selected hydrocarbons at station 17 (48°50.6'N 122°46.2'W)
<*»
MESA I
Nov. 1976
MESA II
March 1977
MESA III
Aug. 1977
Depth S T
(•) (° oo) (°c)
0 29.39 8.68
10 29.39 8.91
20 29.84 8.91
32 29.92 8.91
0
10
20
40
0 24.44 19.82
10 26.05 15.68
21 27.84 13.10
Methane
332
359
418
413
266
272
276
275
586
561
561
Ethane
0.45
0.45
0.54
0.56
0.47
0.46
0.47
0.46
0.45
0.30
0.31
Ethene Propane
(n&/£) STP
1.60
1.67
1.94
1.68
1.49
1.33
1.41
1.33
2.84
1.99
1.77
0.43
0.47
0.53
0.54
0.36
0.36
0.37
0.38
0.90
0.82
0.72
Propene
0.80
0.79
0.88
0.88
0.87
0.80
0.80
0.74
1.19
0.82
0.55
Ethane/Ethene
0.28
0.27
0.28
0.33
0.32
0.34
0.33
0.34
0.16
0.15
0.18
-------
TABLE A.5 Seasonal distributions of selected hydrocarbons at station 23 (48°55.0'N 123°6.5'W)
CO
00
MESA I
Nov. 1976
MESA II
March 1977
MESA III
Aug. 1977
Depth
(m)
1
11
21
61
111
0
10
20
40
60
119
10
20
30
114
os
30.89
31.32
31.35
32.29
32.80
fm
-
-
-
-
28.18
29.01
29.30
30.96
T
9.01
9.04
9.08
8.89
8.65
mf
-
:
-
-
12.70
11.30
11.34
9.76
Methane
511
301
174
379
368
284
273
262
256
267
288
358
352
180
550
Ethane
0.46
0.36
0.34
0.54
0.64
0.46
0.43
0.45
0.46
0.46
0.49
0.78
0.56
0.40
0.58
Ethene
1 n o / 0 i
\ ' '**/ ** 1
1.59
1.61
1.60
1.64
1.88
1.17
1.20
1.17
1.21
1.27
1.26
7.13
5.22
3.80
4.55
Propane
STP
0.60
0.42
0.47
0.68
-
0.30
0.30
0.31
0.34
0.35
0.38
0.66
0.62
0.74
0.63
Propene
1.04
0.87
0.86
0.71
-
0.77
0.74
0.74
0.76
0.73
0.71
2.06
1.67
1.50
1.52
Ethane/Ethene
0.30
0.22
0.21
0.33
0.34
0.39
0.36
0.39
0.38
0.36
0.39
0.11
0.11
0.10
0.13
-------
TABLE A.6 Seasonal distributions of selected hydrocarbons at station 26 (49°2.0'N 123P15.5'W)
to
UD
MESA I
Nov. 1976
MESA II
March 1977
MESA III
Aug. 1977
Depth S
(m) ( /oo)
0 26.41
10 32.23
20 32.39
60 32.52
0
10
20
40
60
188
0 23.67
84 30.44
J Methane
8.51
9.05 439
8.99 528
8.89 537
327
326
242
137
161
790
15.38 273
9.88 339
Ethane
0.64
0.45
0.50
0.56
0.54
0.91
0.33
0.32
0.33
0.45
0.92
0.65
Ethene
2.20
1.59
1.81
1.79
1.46
1.46
0.96
0.90
0.90
1.18
8.86
4.65
Propane
STP
0.60
0.60
1.22
0.49
0.36
0.47
0.34
0.41
0.42
0.38
0.81
0.58
Propene
1,28
0.92
1.51
1.03
1.29
0.95
0.83
0.89
0.97
0.81
2.81
1.52
Ethane/Ethene
0.29
0.28
0.28
0.31
0.37
0.62
0.34
0.36
0.37
0.38
0.10
0.14
-------
TABLE A.7 Seasonal distributions of selected hydrocarbons at station 32 (48°34.3'N 123°13.5'W)
MESA I
Nov. 1976
MESA II
March 1977
.
MESA III
August 1977
Depth S
(m) (°/oo)
0
5
10
20
60
200
0
20
50
100
150
225
J Methane
487
405
487
431
388
382
239
243
227
223
209
195
Ethane
0.64
0.61
0.60
0.66
0.63
0.67
0.44
0.46
0.45
0.51
0.60
0.49
No Data
tthene
(na/i)
1.76
1.88
2.51
2.29
2.13
2.05
1.60
1.49
1.27
1.46
1.18
1.20
Propane
STP
0.63
0.55
0.68
0.65
0.63
0.64
0.32
0.33
0.33
0.46
0.38
0.40
Propene
1.01
0.84
0.95
0.88
0.81
0.81
0.95
0.84
0.76
0.98
0.83
0.88
Ethane/Ethene
0.36
0.32
0.24
0.29
0.30
0.33
0.28
0,32
0.35
0.35
0.51
0.41
------- |