903R93026
CBP/TRS 78/92
March 1993
Guide to Using
Chesapeake Bay Program
Water Quality
Monitoring
Data
A "13107
TD
225
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1993
Chesapeake Bay Program
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F:...J:;rJ!i3fPA 19107
Guide to Using
Chesapeake Bay Program
Water Quality
Monitoring Data
March 1993
Produced under contract to the U.S. Environmental Protection Agency
Contract No. 68-WO-0043
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
-------
GUIDE TO USING CHESAPEAKE RAY PROGRAM WATER QUALITY MONITORING DATA
TABLE OF CONTENTS
I. OVERVIEW 1
A. The Guide 1
B. The Water Quality Monitoring Program 1
C. The Data Base 2
D. Data Request Form 12
II. GENERAL DESCRIPTION 17
A. Monitoring Program Design 17
B. Sample Collection and Water Quality Parameters 18
C. Data Base 19
D. Quality Assurance (QA) 20
E. Program Sponsor 21
F. Participating Agencies 22
III. DATA BASE INFORMATION 25
A. Data Documentation 25
B. Identifier Variables 27
CBP Segment Designation 28
Cruise Identifier 33
Date of Sample Collection 34
Sample Layer 35
Period of Sampling 38
Pycnocline, Lower Depth 39
Pycnocline, Upper Depth 41
Replicate Number 42
Sample Depth 43
Total Depth 44
Sampling Station Identifier 45
Source Agency 47
Sampling Time 48
C. Water Quality Parameters 49
Physical Profile Sampling Methods 50
Dissolved Oxygen 52
Dissolved Oxygen Saturation 53
pH 54
Salinity 55
Secchi Disk Depth 56
Specific Conductivity 57
Water Temperature 58
Specific Gravity 59
Field Filtration Methods 60
Total Phosphorus 62
Total Dissolved Phosphorus 63
Particulate Phosphorus 64
Orthophosphate (filtered) and Dissolved Inorganic
Phosphorus 66
Guide to Using CBP Water Quality Monitoring Data Page i
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Dissolved Organic Phosphorus . 68
Total Nitrogen 69
Total Dissolved Nitrogen 71
Particulate Organic Nitrogen and Particulate Nitrogen .... 73
Total Kjeldahl Nitrogen, Whole and Filtered 75
Nitrite + Nitrate, filtered and Nitrate, filtered 77
Nitrite, filtered 79
Ammonium, filtered 80
Dissolved Inorganic Nitrogen 81
Dissolved Organic Nitrogen and Total Organic Nitrogen .... 82
Total Organic Carbon 83
Dissolved Organic Carbon 85
Particulate Organic Carbon and Particulate Carbon 87
Silica, filtered 89
Total Suspended Solids 90
Chlorophyll a and Phaeophytin, spectrophotometric 91
Chlorophyll a and Phaeophytin, fluorometric 92
D. Other Parameters 93
E. Measured and Calculated Laboratory Parameters 94
F. Lower Detection Limits of Water Quality Parameters 100
G. Data Analysis Issues Tracking System (DAITS) 107
IV. QUALITY ASSURANCE (QA) DATA 113
A. Introduction . 113
B. Within-organization QA data 115
Field QA Data 115
Laboratory QA Data 116
C. Inter-organization QA data 122
Early Split Sample and Co-located Sample Results 122
Coordinated Split Sample Program (CSSP) 122
V. RELATED DOCUMENTATION 123
3/93 Guide to Using CBP Water Quality Monitoring Data Page ii
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LIST OF FIGURES
Figure 1. Maryland portion of the Chesapeake Bay, showing Chesapeake Bay
Monitoring Program stations and segments 4
Figure 2. Virginia portion of the Chesapeake Bay, showing Chesapeake Bay
Monitoring Program stations and segments 5
LIST OF TABLES
Table 1. Mainstem Water Quality Monitoring Stations 6
Table 2. Chesapeake Bay Program segments containing the 49 Mainstem
Monitoring Program stations 9
Table 3. Parameter Titles and Variable Names by Data Category 10
Table 4. Measured and Calculated Laboratory Parameters 95
Table 5. Lower Detection Limits of Water Quality Parameters 102
Table 6. Chesapeake Bay Program Data Analysis Issues Tracking System. . 108
Table 7. Summary of CBP Precision Estimates 114
Table 8. Summary of CBP Accuracy Estimates 115
Table 9. Summary of Laboratory Quality Assurance Data 118
3/93
Guide to Using CBP Water Quality Monitoring Data Page iii
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I. OVERVIEW
A. The Guide
This document describes the Chesapeake Bay Mainstem Water Quality
Monitoring Program in general and provides detailed information about the
existing Program data base. The two main purposes of this document are to
assist those who wish to obtain monitoring data, and to provide
information to data analysts about the data base.
This chapter, highlighted in blue, provides an overview of the Guide and
emphasizes particular elements that should help the potential data user
formulate a data request tailored to his or her needs. It serves as a
common starting point for communication between the user and the data
provider at the CBP Computer Center. Potential data users should read
this chapter, and fill out and submit the data request form at the end of
the chapter, prior to any communication with CBPCC staff.
Some of the information in this document is essential for properly
manipulating (sorting, subsetting) the data. Other facts are important in
designing, implementing and interpreting data analyses. Some topics are
interrelated and may be discussed in more than one place in the Guide.
Users should review the table of contents, list of tables and this
overview to gain information on how this document can be used.
It should be kept in mind that this is a "living" document. As the
Program continues and as the data are used and examined, the contents will
certainly change and be expanded. To that end, we ask that such knowledge
gained by all who work with the data be passed back to the Chesapeake Bay
Program Office (CBPO) to be shared with others and included in the Guide.
B. The Water Quality Monitoring Program
The Chesapeake Bay Program, a cooperative effort between the federal
government and the state and local governments in the Chesapeake Bay
watershed, provides funds to the states of Maryland and Virginia for the
routine monitoring of 19 directly measured water quality parameters at 49
stations in the mainstem Bay. The Water Quality Monitoring Program began
in June 1984 with stations sampled once each month during the colder late
fall and winter months and twice each month in the warmer months. The
three collecting organizations coordinate the sampling times of their
respective stations, so that data for each sampling event, or "cruise",
represent a synoptic picture of the Bay at that point in time. The
sampling frequency has been changed since the beginning, and cruises have
occasionally been disrupted partially or completely due to weather or
mechanical difficulties. Some stations have been dropped from the Program,
others added. Station maps (Figures 1 and 2) and a list of stations
(Table 1) show the station locations.
Monitoring Program sampling locations (see Figures 1 & 2) are identified
in the data base by station name and by latitude and longitude. For some
3/93 Guide to Using CBP Water Quality Monitoring Data Page 1
-------
applications, it may be useful to group stations into geographic regions.
The CBP segmentation scheme (Figures 1 & 2 and Table 2) was based
primarily on long-term salinity data and circulation patterns. A segment
identifier is associated with each data record.
At each station, a hydrographic profile is made (including water
temperature, salinity, and dissolved oxygen) at approximately 1- to 2-
meter intervals. Water samples for chemical analysis (e.g., nutrients and
chlorophyll) are collected at surface and bottom, and at two additional
depths depending on the existence and location of a pycnocline (region(s)
of density discontinuity in the water column). Correlative data on sea
state and climate are also collected, and in some cases additional
optional parameters are available. Some of the monitored chemical
parameters have changed over time, and some of the analytical methods and
limits of detection have also changed since the beginning of the Program.
The water quality parameters monitored routinely by participating agencies
are listed in Table 3.
C. The Data Base
Complete and accurate data and program documentation is of the greatest
importance in providing a data base of known quality. Participating
agencies are required to submit a documentation file with every data
submission. This file provides such information as changes made since
last submission, sampling dates, information on method and detection limit
changes, and notes from cruise and laboratory logs. Copies of these files
are available upon request. Also, documentation of major issues affecting
CBP data analysis is collected and stored through the Data Analysis Issues
Tracking System (DAITS) . See Chapter III, sections A and G for more
information.
Data in the primary data base consist of all directly measured parameters.
For user applications, however, calculated values, such as total nitrogen
and total phosphorus, are provided if the requisite components are
available (see Table 4 in Chapter III, section E for more information).
Each parameter may have associated with it a set of coded variables. One
indicates the particular analytical method (parameter_M), another flags
analytical problems (parameter_A), if any, and another indicates whether
the value is above or below the limit of analytical detection
(parameter_D). In the primary data sets, parameters that are at or below
detection are given the value of the detection limit. See Table 5 for a
list of lower detection limits. However, other options for handling
detection limits are available at the direction of the user: values below
detection can be set to missing or to one-half the detection limit.
Variables that uniquely identify data are STATION, DATE (or CRUISE),
SDEPTH, LAYER, and REP_NUM (Table 3) . These variables are required to
discriminate among data records. Since each station is sampled only once
per date or cruise, TIME is not used as an identifier variable.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 2
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The data base includes several types of quality assurance (QA) data, which
estimate the precision and accuracy of the monitoring data. Refer to
Chapter II, section D, and Chapter IV for more information on QA data.
Again, the above information is only a brief introduction to using the
data base. Everyone who uses these data is encouraged to read the rest of
the Guide for greater detail about the Monitoring Program and the water
quality parameters.
For the benefit of those who wish to search for specific information
without reading all sections, some frequently used acronyms include:
AMQAW Analytical Methods and Quality Assurance Workgroup
CBL Chesapeake Biological Laboratory
CRL Central Regional Laboratory
DAWG Data Analysis Workgroup
DCLS Virginia Division of Consolidated Laboratory Services
DMAW Data Management and Acquisition Workgroup
DMP Data Management Plan
DAITS Data Analysis Issues Tracking System
MDE Maryland Department of the Environment
MDHMH Maryland Department of Health and Mental Hygiene
ODU Old Dominion University
VIMS Virginia Institute of Marine Science
VWCB Virginia Water Control Board
Users of the monitoring data base may contact the CBPO at (800) 523-2281
for additional information.
A "Data Request Form" follows the figures and tables in this chapter.
This should be used for all requests for CBP Water Quality Monitoring
data.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 3
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Maryland Chesapeake Bay Mainstem
Water Quality Monitoring Stations And
Segment Designators
fETTi
BALTIMORE
WASHINGTON D.C.
15 30 45
MILES
Figure 1. Maryland portion of the Chesapeake Bay, showing Chesapeake Bay
Monitoring Program stations and segments.
Guide to Using CBP Water Quality Monitoring Data Page 4
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Virginia Chesapeake Bay Mainstem
Water Quality Monitoring Stations And
Segment Designators
10 20
MILES
Figure 2. Virginia portion of the Chesapeake Bay, showing Chesapeake Bay
Monitoring Program stations and segments.
Guide to Using CBP Water Quality Monitoring Data Page 5
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Table 1. Mainstem Water Quality Monitoring Stations.
CBP CBP AGENCY LATITUDE LONGITUDE MEAN NUMBER NOTES
STATION SEGMENT DD MM SS DD MM SS DEPTH1 SAMPLES2
(Stations located in the Chesapeake Bay mainstem)
CBl.l
CB2.1
CB2.2
CB3.1
CB3.2
CB3.3C
CB3 . 3E
CB3.3W
CB4 . 1C
CB4 . 1W
CB4.2C
CB4.2E
CB4 . 2W
CB4.3C
CB4.3E
CB4 . 3W
CB4.4
CB5.1
CBS. 2
CBS. 3
CBS. 4
CB5.4W
CBS. 5
CB6.1
CBS. 2
CB6.3
CB6.4
LE3.6
CB7.1
CB7 . IN
CB7.1S
CB7.2
CB7.2E
CB7.3
CB7.3E
CB7.4N
EE3.5
CB7.4
CB8.1
CBS. IE
LE5.5
CB1
CB2
CB2
CB3
CBS
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CB4
CBS
CBS
CBS
CBS
CBS
CBS
CB6
CBS
CBS
CBS
CBS
CB7
CB7
CB7
CB7
CB7
CB7
CB7
CB7
CB7
CBS
CBS
CBS
CBS
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
MD/MDE
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/ODU
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/ODU
VA/ODU
VA/ODU
VA/VIMS
VA/ODU
VA/ODU
VA/ODU
VA/ODU
39 32
39 26
39 20
39 15
39 09
38 59
39 00
39 00
38 49
38 48
38 38
38 38
38 38
38 33
38 33
38 33
38 24
38 19
38 08
37 54
37 48
37 48
37 41
37 35
37 29
37 24
37 14
37 35
37 41
37 46
37 34
37 24
37 24
37 07
37 13
37 03
37 47
36 59
36 59
36 56
36 59
48
24
54
00
54
45
12
12
36
51
48
42
36
24
24
27
48
06
12
42
00
48
30
18
12
41
11
48
00
30
52
41
41
00
43
29
33
36
15
42
48
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
76
75
75
76
76
76
76
76
75
75
76
76
76
76
04
01
10
14
18
21
20
23
24
27
25
24
30
26
23
29
20
17
13
10
10
17
11
09
09
09
12
17
59
58
03
04
01
07
03
58
50
00
10
01
18
54
30
30
24
30
36
48
18
00
54
06
06
06
12
30
36
36
36
45
06
30
42
24
45
24
36
30
06
24
30
30
48
30
32
15
23
37
38
05
30
12
6.2
6.2
12.0
12.5
11.6
23.5
8.4
9.1
31.8
9.3
27.0
9.4
9.4
26.2
22.3
9.7
29.6
33.9
30.2
26.5
32.4
5.5
18.8
13.2
11.2
12.8
10.6
10.0
25.3
31.7
16.0
21.8
13.4
13.6
17.9
12.9
27.0
14.0
10.6
19.5
22.1
2
2
4
4
4
4
2
2
4
2
4
2
2
4
4
2
4
4
4
4
4
2
4
4
4
4
4
2
2
2
2
2
2
4
2
2
2
4
2
2
2
3
3
3
3
3
3
5
6
6
6
6
6
7
7
8
,4
,4
,4
,4
,4
,4
3/93 Guide to Using CBP Water Quality Monitoring Data Page 6
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Table 1 (continued). Mainstem Water Quality Monitoring Stations.
CBP CBP AGENCY LATITUDE LONGITUDE MEAN NUMBER NOTES
STATION SEGMENT DD MM SS DD MM SS DEPTH1 SAMPLES2
(Mainstem stations located in tributary segments)
CB4
EE3
LE2
LE3
WE 4
WE 4
WE 4
WE 4
.IE
.4
.3
.7
.1
.2
.3
.4
EE1
EE3
LE2
LE3
WE 4
WE 4
WE 4
WE4
MD/MDE
VA/VIMS
MD/MDE
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
VA/VIMS
38
37
38
37
37
37
37
37
(Stations sampled
CB4
CB4
CB4
CBS
.OC
.OE
.OW
.3
CB4
CB4
CB4
CBS
MD/MDE
MD/MDE
MD/MDE
VA/VIMS
38
38
38
37
49
54
01
31
18
14
10
06
as
55
55
55
54
00
30
18
50
42
30
36
36
part
37
37
38
42
76 22
75 47
76 21
76 18
76 20
76 23
76 22
76 17
18
30
00
25
48
12
24
36
of special
76 23
76 23
76 25
76 10
41
14
59
00
23.1
4.8
20.0
7.3
6.2
13.9
5.8
7.5
projects)
31.3
8.4
9.0
26.5
4
2
4
2
2
2
2
2
4
0
0
4
3
9
9
9
5
1 The "Mean Depth" (meters) was computed from total depth using June,
1984 through December 1990 water quality data.
2 The "Number Samples" represents the number of nutrient samples which are
collected during each cruise at that station. Some stations are
considered "pycnocline stations" and have four samples collected
(S,AP,BP,B), others have only two samples collected (S,B). The pycnocline
is the region of the water column where density changes rapidly due to
salinity and temperature differences.
3 Stations not sampled during "Winter." This is generally the November
through the first March cruise beginning with BAY075, March, 1988.
4 CB3.3E, CB3.3W, CB4.1W, CB4.2E, CB4.2W, and CB4.3W had four
nutrient samples collected until cruise BAY075.
5 Station CBS.3 was also sampled by VIMS from the start of the program
in June, 1984 through April, 1990. The VIMS data for station CBS.3 was
removed from the database to avoid confusion due to duplicate samples. It
is available upon request.
6 CBS.4, CBS.5, CB6.1, CB6.2, and CB6.3 had only two nutrient samples
collected until cruise BAY013.
7 CB6.4 and CB7.3 had only two nutrient samples collected until BAY021.
8 CB7.4 had only two nutrient samples collected until cruise BAY019. From
then until BAY050, four samples were collected when a pycnocline was
detected. After cruise BAY050 four samples were always collected.
9 Stations CB4.0C, CB4.0E, and CB4.0W were sampled from June through
October, 1990 as part of a study funded by the Baltimore Port Authority
to determine the feasibility of using the trough to dump dredging
spoils. Stations CB4.0E and CB4.0W were only sampled for physical
profile parameters and had no nutrient samples collected.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 7
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Table 2. Chesapeake Bay Program segments containing the 49 Mainstem Monitoring
Program stations.
SEG. SEGMENT NAME
CODE
MAINSTEM MONITORING PROGRAM STATIONS
CB1 Northern Chesapeake Bay
CB2 Upper Chesapeake Bay
CB3 Upper Central Chesapeake Bay
CB4 Middle Central Chesapeake Bay
CBS Lower Chesapeake Bay
CBS Western Lower Chesapeake Bay
CB7 Eastern Lower Chesapeake Bay
CBS Mouth of the Chesapeake Bay
EE1 Eastern Bay
EE3 Tangier/Pocomoke Sounds
LE2 Lower Potomac River
LE3 Lower Rappahannock River
WE4 Mobjack Bay
CB1.1
CB2 .1, CB2 . 2
CB3.1, CB3.2
CB3.3W, CB3.3C, CB3.3E, CB4.1W,
CB4.1C, CB4.2W, CB4.2C, CB4.2E,
CB4.3W, CB4.3C, CB4.3E, CB4.4 (PLUS
CB4.0W, CB4.0C, CB4.OE in deep
trench)
CB5.1, CBS.2, CBS.3, CB5.4W, CBS.4,
CBS. 5 (PLUS tributary station
CB5.1W*)
CB6.1, CB6.2, CB6.3, CB6.4, LE3.6
CB7.1, CB7.1N, CB7.1S, CB7.2, CB7.2E,
CB7.3, CB7.3E, CB7.4N, EE3.5
CB8.1, CB8.1E, CB7.4, LE5.5
CB4.1E (PLUS tributary station
EE1.1*)
EE3.4 (PLUS tributary stations EE3.0,
EE3.1, EE3.2, andEE3.3*)
LE2.3 (PLUS tributary station LE2.2*)
LE3.7 (PLUS tributary stations LE3.1,
LE3.2, LE3.3, and LE3.4*)
WE4.1, WE4.2, WE4.3, WE4.4
* These stations are sampled as part of the Tributary Monitoring Program, and are
included here to show all the stations that are in these segments.
Guide to Using CBP Water Quality Monitoring Data Page 9
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Table 3. Parameter Titles and Variable Names by Data Category.
PHOSPHORUS:
NITROGEN:
CARBON:
OTHER LAB
PARAMETERS :
FIELD
PARAMETERS:
Total Phosphorus TP
Total Dissolved Phosphorus ..... TOP
Particulate Phosphorus .... PHOSP
Orthophosphate PO4F
Dissolved Inorganic Phosphorus DIP
Dissolved Organic Phosphorus OOP
Total Nitrogen TN
Total Dissolved Nitrogen TDN
Particulate Organic Nitrogen and Particulate Nitro-gen
PON
Total Kjeldahl Nitrogen, Whole/Filtered . . TKNW,TKNF
Nitrite + Nitrate, Filtered ..... NO23
Nitrite, Filtered NO2
Nitrate, Filtered ... NO3
Ammonium, Filtered NH4
Dissolved Inorganic Nitrogen DIN
Dissolved Organic Nitrogen ... DON
Total Organic Nitrogen TON
Total Organic Carbon ........ TOC
Dissolved Organic Carbon DOC
Particulate Organic Carbon and Particulate Carbon POC
Silica, Filtered SI
Total Suspended Solids TSS
Chlorophyll a and Phaeophytin,
Spectrophotometric ........... CHLA, PHEA
Dissolved Oxygen ..... DISOXY
Dissolved Oxygen Saturation . DO_SAT
pH PH
Salinity .......... SALIN
Secchi Disk Depth SECCHI
Specific Conductivity . COND
Water Temperature WTEMP
Air Temperature ATEMP
Cloud Cover CLOUD
Tidal Stage TIDE
Wave Height WAVHGT
Wind Direction WINDIR
Wind Speed WINDSPD
Specific Gravity . SIG_T
Chlorophyll a, Fluorometric CHLAF
3/93
Guide to Using CBP Water Quality Monitoring Data Page 10
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Table 3 (continued). Parameter Titles and Variable Names by Data Category.
SAMPLE IDENTIFIER
VARIABLES: CBP Segment . SEGMENT
Cruise Identifier ...... CRUISE
Date of Sample Collection DATE
Period of Sampling PERIOD
Pycnocline, Lower Depth ........... PDEPTHL
Pycnocline, Upper Depth . PDEPTHU
Replicate Number REP_NUM
Sample Depth SDEPTH
Total Depth TDEPTH
Sample Layer LAYER
Sampling Station Identifier . . STATION
Latitude LAT
Longitude LONG
Basin Name . BASIN
River Code . RIVER
Sampling Time TIME
Source Agency SOURCE
3/93 Guide to Using CBP Water Quality Monitoring Data Page 11
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D. Data Request Form
Chesapeake Bay Program mainstem water quality monitoring data are
available by request from the Chesapeake Bay Program Office (CBPO). The
purpose of the Request Form is to provide for a clear and concise
statement of the scope of each request for CBP Water Quality data.
Responsibilities for fulfilling data requests are divided between CBPO
program management staff and the computer center staff. The program
management staff normally handle the initial contact with a data
requestor, including distribution of the "Guide," which contains this
form, to be used when requesting data. After receiving a data request,
the program management staff approve and then prioritize the data request.
They may coordinate with the data originator, as required, to determine
appropriate uses of the data. The program management staff also review
data output before releasing it to the requestor. The computer center
staff normally complete the data base retrieval and output portions of the
data request.
The data user should read Chapter I of the "Guide" before filling out the
request form.
Please return the completed Request Form to:
U.S. EPA Chesapeake Bay Program
Information Center
410 Severn Ave, Suite 109
Annapolis, MD 21403
1. REQUESTOR INFORMATION
Name: Organization:
Address:
City: State: Zip:
Phone: (Voice) (FAX)
2. INTENDED USE
Please describe the intended use of the data. Please be specific, and attach
additional pages if needed.
Guide to Using CBP Water Quality Monitoring Data Page 12
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3. TIME PERIOD
The CBP Mainstem Water Quality Monitoring Program began in June or July 1984,
depending on stations of interest. The most recent data available are usually
several months behind the current calendar month. Time Period may be indicated
by choosing a range of dates, specific months, specific years, a range of
cruises, or specific cruises.
Range:
Month/Year: to
or
Cruise: to
Specific: (Please indicate clearly)
4. GEOGRAPHIC LOCATION
Please list either CBP segment codes or CBP station names. Copies of the
monitoring station maps (Figures 1 & 2) , with the stations of interest indicated
clearly, may be substituted here.
Segments:
Stations:
3/93 Guide to Using CBP Water Quality Monitoring Data Page 13
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5. VARIABLES
Please choose the variables of interest by placing an 'X' in the space provided.
The five required identifier variables have already been marked.
( D: detection limit flag, _M: method code)
X_ STATION
X_ DATE
TIME
X SDEPTH
X REP NUM
X
LAYER
SOURCE
CRUISE
PERIOD
SEGMENT
LAT
LONG
BASIN
RIVER
PDEPTHU
PDEPTHL
TDEPTH
SECCHI
SECCHI_D
SECCHI M
PH
PH_D
PH_M
COND
COND_D
COND_M
SALIN
SALIN_D
SALIN_M
WTEMP
WTEMP_D
WTEMP_M
DISOXY
DISOXY_D
DISOXY_M
DO_SAT
SIG T
TSS
TSS_D
TSS_M
SI
SI_D
SI_M
TOC
TOC_D
TOC_M
DOC
DOC_D
DOC_M
POC
POC_D
POC M
ATEMP
ATEMP_D
ATEMP_M
CLOUD
TIDE
WAVHGT
WINDIR
WINDSPD
TON
TDN_D
TDN_M
PON
PON_D
PON_M
NO23
NO23_D
NO23_M
NH4
NH4_D
NH4_M
N02
N02_D
N02 M
TN
TN_D
TN_M
DIN
DIN_D
DIN_M
DON
DON_D
DON_M
N03
NO3_D
NO3_M
TON
TON_D
TON M
TKNF
TKNP_D
TKNF_M
TKNW
TKNW_D
TKNW M
CHLA
CHLA_D
CHLA_M
PHEA
PHEA_D
PHEA_M
CHLAF
TP
TP_D
TP_M
TDP
TDP_D
TDP_M
PHOSP
PHOSP_D
PHOSP_M
PO4F
PO4F_D
PO4F_M
OOP
DOP_D
DOP M
Guide to Using CBP Water Quality Monitoring Data Page 14
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6. OUTPUT FORMAT
Please indicate the desired transfer format for the data output. (Printed output
may be available for small requests.)
Choose one option for Transfer Media, and one option from each side of either the
SAS Data Set box or the ASCII File box.
Transfer Media
9 track tape
8 mm tape
3.5" High Density IBM diskette
SAS Data Set
VAX format
SAS Transport format
Version 5
Version 6.06
Version 6 . 07
- or -
ASCII File
column delimited
tab delimited
wide file, with
80 column file,
132 column file,
one observation per line
multiple lines per obs .
multiple lines per obs.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 15
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II. GENERAL DESCRIPTION
A. Monitoring Program Design
The design of the current monitoring program was laid out in Appendix F of
CBP (1983b), "Chesapeake Bay: A Framework for Action." This design built
on previous Chesapeake Bay monitoring programs, avoiding their weaknesses
while addressing monitoring, research, and management needs in an
integrated fashion. The authors proposed a "Water Quality Baseline
Monitoring" design (CBP 1983b, Appendix F, Attachment 6) that was largely
followed in the current CBP monitoring program. A fundamental part of the
design was sampling for nutrients above and below the pycnocline at
stratified stations, in addition to surface and bottom samples. The
pycnocline is the region of the water column where density changes rapidly
due to salinity and temperature differences. Previous monitoring had used
fixed-depth sampling, which did not always characterize the upper and
lower water masses at stratified stations. The authors also stressed the
need for "built-in flexibility," which is an important part of the current
program. This flexibility is illustrated by the changes that have
occurred in the CBP monitoring program since 1984.
The Chesapeake Bay Mainstem Water Quality Monitoring Program is documented
in CBP (1989) , "Chesapeake Bay Basin Monitoring Program Atlas." It began
in June 1984 with 50 stations (currently 49 are sampled): 22 in Maryland
and 28 in Virginia, sampled once each month during the late fall and
winter months and twice each month in the warmer months. Surface and
bottom samples are collected for nutrient analysis at all stations, and
two mid-water samples, from above and below the pycnocline, are added
where the water column is stratified. The three collecting organizations,
Maryland Department of the Environment (MDE), Old Dominion University
(ODD), and Virginia Institute of Marine Science (VIMS), attempt to sample
their respective stations over the same three-day time period, so that the
data for each sampling period or "cruise" as it is named in the data base,
represent a synoptic picture of the Bay at that point in time {CBP 1985).
The sampling frequency has been changed since the beginning of the
program, and cruises have occasionally been disrupted partially or
completely due to weather or mechanical difficulties. In the beginning of
the program (1984) water quality data were collected once in November,
December, January, and February, and twice in all other months. Beginning
in 1988, to reduce program costs, the Virginia institutions eliminated one
of the March collections; Maryland continued the original schedule.
Through 1991, data from cruises BAY075, BAY095, BAY115, and BAY135 (the
second of the March cruises for 1988 through 1991 respectively) cover
Maryland stations only. Beginning in 1989, VIMS and ODU began sampling
only once in October, therefore, cruises BAY109 and BAY129 (the second
October cruise for years 1989 and 1990 contain only Maryland data. While
Maryland continued with two March and two October collections, sampling
the lateral stations during the winter season was discontinued. One
station has been dropped from the program (VIMS sampling of CBS.3 in May
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Guide to Using CBP Water Quality Monitoring Data Page 17
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1990) and others temporarily added for dredge spoil sampling beginning
with cruise BAY120 (CB4.0E, CB4.0C, CB4.0W June through October, 1990).
Table 1 lists the CBP mainstem station name, CBP segment, the agency which
samples that station, latitude, longitude, mean total depth in meters, and
the number of nutrient samples collected during each cruise. The stations
are grouped in three sections: 1) stations located in the mainstem, 2)
stations located in tributary segments, sampled as part of the mainstem
monitoring program, and 3) stations sampled as part of special projects.
Refer to the table notes for additional information. Table 2 lists the
CBP segments that include the 49 mainstem monitoring program stations, for
data users that want to request the data from all stations in a particular
segment. Note that the station name prefix does not always correspond to
the segment name. The reader is also referred to Chapter III, Identifier
Variables - SEGMENT, and to CBP (1989), "Chesapeake Bay Basin Monitoring
Program Atlas," and CBP (1990), "Chesapeake Bay Segmentation Scheme."
In months when two cruises are scheduled, the first cruise is typically
planned between the 1st and 15th of the month, and the second cruise
between the 16th and the last day of the month. In months when only one
cruise is planned, the cruise may take place at any time and usually
depends on weather conditions. In general, Maryland requires three days
to cover its stations, VIMS requires two days, and ODU requires one to two
days.
The several collecting institutions attempt to sample over the same time
period and visit stations in the same order at approximately the same time
of day on each cruise. Deviations from this schedule exist with sampling
dates varying between collecting institutions by more than a week. In
general, with respect to order and time of day, Maryland stations have
been sampled most consistently. VIMS stations have been sampled least
consistently primarily because of time constraints, distance between
stations, and weather.
B. Sample Collection and Water Quality Parameters
At each station, a hydrographic (phyBiochemical) profile is made and water
samples for chemical analysis are collected at the surface and the bottom
layers, and (for deeper stations) at two additional mid-water depths
depending on the existence and location of a pycnocline. The pycnocline
is the region of the water column where density changes rapidly due to
salinity and temperature differences. Generally, samples have been
collected via pumping system rather than a discrete sample collection
device. The chemical parameters include suites of phosphorus, nitrogen,
and carbon species; silica; photosynthetic pigments; and suspended solids.
Refer to Table 3 for a list of parameter titles and corresponding data
base names. This list includes chemistry profile parameters for
phosphorus, nitrogen, and carbon species, field profile parameters, and
sample identifier variables. Additional discussion on these variables
follows in Chapter III, sections B and C.
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A few of the specific parameters have changed over time, and some of the
analytical methods and limits of detection also have changed since the
beginning of the program, with some inconsistency among data collecting
organizations and analytical laboratories (see Table 4, "Measured and
Calculated Laboratory Parameters, " and Table 5, "Lower Detection Limits of
Water Quality Parameters"). There have been inconsistencies among
collecting laboratories in the depth - relative to the pycnocline - at
which samples and measurements were collected (see Chapter III, section B,
"Sample Layer and Sample Depth" and CBP 1985, "Monitoring 1984," p. 15) .
C. Data Base
Electronic data files from the monitoring cruises are sent to the CBPO by
the participating agencies. These files contain concentrations from the
19 sampled parameters, along with cruise information such as station,
sample date, time, cruise number, sample depth, replicate number,
latitude, longitude, sea state, and weather. Data are required to be
submitted to the CBPO within 60 days of the end of the month in which the
sample was collected along with the appropriate documentation for that
data submittal.
After QA and verification procedures are completed at CBPO, the data
submitter is asked to review and comment or correct any errors or out of
range data that are flagged by the verification programs (refer to lists
of outliers in CSC 1991 and CBP 1992b) . After signoff by the data
submitter, the data are available upon request.
Two levels of the monitoring data base, now containing well over 120,000
observations, are supported at the CBPO. The first level consists of all
directly measured parameters (no derived or calculated parameters with the
exception of chlorophyll_a and phaeophytin). See Chapter III, section C,
Water Quality Parameters. Each parameter has with it a set of coded
variables. One indicates the particular analytical method, another flags
analytical problems, if any, and another indicates whether the value is
above or below the limit of analytical detection. In the first level data
sets, parameters that are below the level of detection are given the value
of the detection limit and the detection limit flag is set to "<". The
analytical problem codes have been used and interpreted inconsistently
among agencies (MDE and VIMS use CBPO codes and ODU currently notes
problems in their data set documentation). Refer to the Data Management
Plan (CBP 1992a) for valid analytical problem codes and their definitions.
Second-level data sets are generated via a menu-driven data selection
program for general user requests. The data sets may include primary and
documentary data variables, and alternative options for handling detection
limit values may be selected (e.g., set to missing, set to one-half the
detection limit value). The method codes should be viewed as a general
description of the method; each laboratory may interpret the method
slightly differently or make small modifications over time. Analytical
Guide to Using CBP Water Quality Monitoring Data Page 19
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problem codes are not currently available in routine retrievals from this
second-level data base.
Certain useful parameters which are not measured directly but which can be
calculated are also available (e.g., total nitrogen may be obtained by
summing specific directly measured nitrogen species). Users should be
aware that calculated values may be derived from constituents below
detection limit, and this may have an effect on user applications.
In addition to these calculated variables, other identifier variables have
been added to the second-level data base to facilitate grouping data in
space and time (i.e., BASIN, equal to "Chesapeake" in the mainstem data,
RIVER equal to tributary name, and PERIOD equal to the range of dates
covered in one "cruise").
The structure of the CBPO Monitoring Program data sets is based both on
the sampling design and on the requirements of the data management
software (SAS) . The water quality data sets are stored and manipulated as
SAS data sets, which consist of a series of similarly structured records,
each of which contains all the variables of the data set, whether assigned
a value or not. A header record carries information about the station
which is not associated with any particular sample or sample depth, e.g.,
Secchi depth, station depth, pycnocline depth, weather and sea state.
Sample depth in the header record is always equal to 0, and the sample
depth for water quality data records is always greater than 0; surface is
usually 0.5 or 1 meter. At the minimum, all valid records should carry
non-missing values for participating agency, cruise number, station, date,
sample depth, latitude, and longitude.
Documentation of any problems with data quality is also an important part
of a monitoring program. Documentation of major issues affecting CBP data
analysis and data quality is collected and stored through the Data
Analysis Issues Tracking System (DAITS). This system is used to solicit
information and track the resolution of analytical method and data
analysis issues that arise. See Chapter III, Table 6 for more details and
a listing of issues.
D. Quality Assurance (QA)
The goal of quality assurance is to provide the data user with data of
known and high quality. The first stage of quality assurance is quality
control (QC), which is performed by personnel at the analysis laboratory
to ensure that data leaving the laboratory meet quality standards (Taylor
1987) . In the second stage, data users employ the same data in slightly
different ways to assess the quality of the data being analyzed. Since
the intended audience of this document is data users, the focus here is on
this second stage, assessing the quality of data being analyzed.
Quality assurance data for chemical analyses measure two quantities,
precision and accuracy. Precision is the repeatability of measurements.
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and accuracy is the closeness of analytical measurements to a "true"
value. CBP QA data include precision and accuracy comparisons within the
same organization, and among results from different organizations.
To assess within-organization precision and accuracy, approximately 10% of
the chemical analyses for each parameter are analyzed in duplicate and
spiked in the laboratories. Laboratory replicate and spike data are
submitted to CBPO separately from monitoring data and are maintained in
separate QA data sets. At some stations, field replicates are also
generated, and these are reported with the regular monitoring data.
Within-organization QA data are described and summarized in detail in
Chapter IV.
Inter-organization precision and accuracy are assessed by the Coordinated
Split Sample Program (CSSP), which includes comparisons of the results
from field split samples analyzed by different laboratories. CSSP results
also include another measure of accuracy, from Standard Reference Material
(SRM) analyses. CSSP data are described in detail in Chapter IV.
Another aspect of quality assurance is detection limits. The minimum
detection limit (MDL) is the lowest concentration of a parameter that the
measurement system can detect reliably. At CBP laboratories, the MDL is
currently determined from 3 times the standard deviation of seven
replicates of a low-level ambient water sample. In the CBP data base,
when measurements are below the MDL, the value of the variable is set to
the detection limit and the detection limit flag, variable_D, is set to
"<". Detection limits for many parameters have been lowered over the life
of the program. See Table 5, "Lower Detection Limits of Water Quality
Parameters" for a detailed listing. Some parameters also have upper
detection limits, but since most parameters can be diluted and re-analyzed
when these are encountered, they rarely result in censored values in the
data base.
Water quality values may be removed from CBP data sets (set to missing and
flagged with the analytical problem code, variable _A) for a variety of
quality control reasons. The "rules" by which data are removed and
flagged with a code have evolved over the life of the program (see DAITS
#1 for details).
E. Program Sponsor
U.S. Environmental Protection Agency
Chesapeake Bay Program Office (CBPO)
410 Severn Avenue
Annapolis, MD 21403
(410) 267-0061
(800) 523-2281
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F. Participating Agencies
Maryland Grantee:
Maryland Department of the Environment (MDE)
Chesapeake Bay and Watershed Management Administration
Chesapeake Bay and Special Projects Program
2500 Broening Highway
Baltimore, MD 21224
(Originally Office of Environmental Programs [OEP], Department of
Health and Mental Hygiene, Baltimore, MD through 1986)
Maryland Laboratories:
EPA Central Regional Laboratory (CRL)
839 Bestgate Road
Annapolis, MD 21401
(6/84-5/15/85, analyses done by OEP staff)
Maryland Department of Health and Mental Hygiene (MDHMH)
Lab Administration
P.O. Box 2355
Baltimore, MD 21201
(tributaries, and mainstem chlorophyll)
University of Maryland Chesapeake Biological Laboratory (CBL)
P.O. Box 38
Solomons, MD 20688
(5/16/85-present)
Maryland Field Operations:
Maryland Department of the Environment (MDE)
416 Chinquapin Round Rd.
Annapolis, MD 21401
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Virginia Grantee:
Virginia Water Control Board (VWCB)
Chesapeake Bay Office
P.O. Box 11143
Richmond, VA 23230-1143
Virginia Subcontractors (Field and Lab Operations):
Old Dominion University (ODU)
Applied Marine Research Laboratory
College of Sciences
Norfolk, VA 23529-0456
Virginia Institute of Marine Science (VIMS)
College of William and Mary
Gloucester Point, VA 23062
See Table l for a complete list of the stations sampled by each
organization.
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III. DATA BASE INFORMATION
This chapter provides specific information on the data base in the
following sections:
A: Data Documentation, used to store information about sample collection
and analysis, and specific information about that sampling cruise;
B: Identifier variables, used to uniquely identify each observation;
C: Water quality parameters. including physical profile parameters
analyzed in the field and laboratory parameters;
D: Other parameters, including information on sampling conditions such as
weather and sea state;
B: Measured and Calculated Laboratory Parameters, a table of which
parameters were directly measured, and what other parameters were
calculated from them, during different time periods at each laboratory;
F: Lower Detection Limits of Laboratory Parameters, a table of the lower
Method Detection Limits (MDLs) for each directly measured and calculated
water quality parameter, organized by parameter and laboratory; and
G: Data Analysis Issues Tracking System (DAITS). an explanation of this
documentation system with a table of the issues.
A. Data Documentation
Complete and accurate data and program documentation is considered to be
of the highest importance. This serves as the basis for providing a data
base of known quality. Participating agencies are required to submit a
data set documentation (DSDOC) file with every data submission. This file
provides such information as:
o changes made since last submission;
o sampling dates and cruise number;
o information on method and method detection limit (MDL)
change s;
o parameter methods table, and;
o notes from cruise and laboratory logs.
The DSDOC is supposed to serve as "living" documentation and should
include any information that would assist in the analysis and
interpretation of the data in the future. The SAS program that is used to
convert the data set to CBP format and add required CBP variables is
appended to the DSDOC supplied by the data submitter. Any changes to the
data made during the conversion process or subsequently should be recorded
there, and the results of the routine CBPO range-checking procedure is
Guide to Using CBP Water Quality Monitoring Data Page 25
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also included. These files are available to the user upon request. Refer
to the Data Management Plan (CBP 1992a) to see the complete DSDOC form.
Project documentation is also requested for each grant year and is
intended to provide an overview of the entire project. At this time,
these are out of date. The complete form is available in the Data
Management Plan (CBP 1992a) . Some of the questions the form contains are:
o project title;
o project beginning and ending date, and sampling schedule;
o EPA QA/QC officer, EPA project officer, and EPA project
number;
o principal investigator, project manager, QA/QC manager, and
data manager;
o administrative organization, collecting organization, and
analytical laboratory;
o project summary;
o parameter list;
o station table and station description; and,
o data entry and verification methods.
Quarterly reports are submitted to the CBPO and provide some additional
information such as the reason why some stations were not sampled and
changes in methods or procedures. Quarterly reports are generally not
available to the user, but information from these reports has been added
to the water quality parameter descriptions in Chapter III.
The CBP Monitoring Cruise Summary is also requested with each data
submission. This form summarizes the sample collection activities during
the entire cruise. The summary contains questions on:
o field sample collection; and,
o electronic instrument calibration.
A field summary sheet for each day of the cruise is attached to the cruise
summary. This lists specific information and measurements relative to
each station such as:
o field observations and comments;
o weather;
o station arrival and departure time;
o refrigerator and freezer temperatures; and,
o meter calibration information for dissolved oxygen,
temperature, and pH.
A third form, Chesapeake Bay Monitoring Program Procedure Modification
Tracking Form, should be completed for cases where major changes occur in
sampling or analytical procedures. This form is used to request approval
for modifications and to document approved modifications made to CBPO
procedures or methods. This form asks for information on:
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o type of procedure;
o duration of method change;
o method description;
o justification for modification;
o analytical parameters that may be affected by this change;
o affected QA plans; and,
o affected cruises.
This information is available upon request. The complete forms are
included in the "Recommended Guidelines for Sampling and Analysis in the
Chesapeake Bay Monitoring Program" (AMQAW, in draft).
B. Identifier Variables
When using the CBP water quality monitoring data, it is important to
become aware of how the data are organized in the data base, and of the
issues associated with individual variables. The following section on
identifier variables pertains to those variables in the data base that
describe sampling location, depth in the water column, and time and date
of the sample. The variables are organized alphabetically by title, and
each variable description includes the parameter name, units of measure,
associated CBP method codes, description of the general method,
description of method changes, DAITS and other issues pertaining to that
variable, and references to other documentation.
Identifier variables used to uniquely locate data observations are
STATION, DATE, LAYER, SDEPTH, and REP_NUM. These parameters provide the
key to use in sorting data accurately. Additional parameters, SOURCE,
CRUISE, TIME, TDEPTH, PDEPTHU, PDEPTHL, SEGMENT, LAT, LONG, BASIN, RIVER,
and PERIOD provide important information about the sample but are not used
to identify unique observations. The SOURCE variable contains the
participating agency code. CRUISE allows the user to separate bay-wide
sampling events. Since each agency samples a station only once per
cruise, the variable TIME is not required to discriminate among samples.
The parameters TDEPTH, PDEPTHU, and PDEPTHL are coded only on the
observation with SDEPTH = 0. This is the first observation in the logical
record for one station and is often referred to as the header record.
SEGMENT is useful when it is necessary to group stations together by
geographic region. LAT and LONG are the latitude and longitude of the
sampling station, in degrees and decimal degrees. BASIN and RIVER
indicate geographic area codes that are listed in the "Chesapeake Bay
Program Data management Plan" (CBP 1992a). PERIOD allows the user to
label data reports and graphics by a range of dates.
The identifier variables in the CBP data base are described on the
following pages.
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Guide to Using CBP Water Quality Monitoring Data Page 27
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TITLE: CBP SEGMENT DESIGNATION
PARAMETER NAME: SEGMENT
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
The Chesapeake Bay segments are geographical units to be used in the
analysis of water quality data. They are based on the circulation
and salinity properties of different areas of the Bay. The
following text describes all of the segments in the CBP segmentation
scheme, including those in the tributaries, based on CBP (1983a),
"Chesapeake Bay: A profile of environmental change." These
descriptions, and the CBP segmentation scheme itself, were based on
monitoring data from 1949-1980, and may not necessarily reflect
current conditions. Salinities mentioned are "long-term summer mean
salinity" (CBP 1983a), but it was not stated if this was surface or
bottom salinity, or some combination of the two. Their original
names had a hyphen, but this was dropped when the SEGMENT variable
was created in the data base.
MAIN BAY SEGMENTS:
Segment CB1 is the uppermost segment of the mainstem of Chesapeake
Bay encompassing the Susquehanna Flats. It is characterized as a
tidal freshwater region and is dominated by freshwater inflow. This
area is resident habitat for freshwater fish and the spawning area
for anadromous and semi -anadromous fish.
Segment CB2 is in the upper portion of the Chesapeake Bay mainstem.
This segment is a transition zone between freshwater and marine
habitats. The salinity is this segment generally ranges from 3 to
9 ppt. This zone is the region of maximum turbidity due to
suspended sediments which cause light limitation to phytoplankton
production most of the year. The transition zone generally found in
this segment is characterized partially as a sediment trap
concentrating suspended sediments including adsorbed toxic
chemicals.
Segment CB3 is the uppermost reach for the estuarine zone in the
mainstem of the Chesapeake Bay. It is characterized by moderate
salinity (7 to 13 ppt) and has two-layer estuarine circulation
driven by freshwater inflow. This segment is generally the upstream
limit for deep-water anoxia.
Segment CB4 is considered to be in the upper portion of the central
Chesapeake Bay mainstem. Salinity ranges from 9 to 14 ppt, and the
water is rich in nutrients. During the summer months this segment
generally experiences oxygen depletion at depths greater than 9.2
meters creating an anoxic habitat for benthic animals.
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CBP SEGMENT DESIGNATION continued:
Segment CBS is located in the central portion of the mainstem of the
Chesapeake Bay. It is influenced by flow from both the Potomac
River and the Patuxent River, and its waters are generally high in
nutrients. The salinity in this segment ranges from about 10 to 17
ppt. This segment contains most of the Bay's deepest waters and is
subject to deep water anoxia in the summer months.
Segment CB6 is located in the lower west-central portion of the
mainstem of Chesapeake Bay. It is characterized by a net southward
flow and by salinities ranging from about 14 to 21 ppt. This
segment is influenced greatly by the major western tributaries.
Segment CB7 is located in the lower east-central portion of the
mainstem. This segment is characterized by a net northerly flow
pattern and by salinities of about 19 to 24 ppt. This segment is
influenced by incoming Atlantic Ocean tidal waters.
Segment CBS is the southern-most segment of the Bay. This segment
is characterized by a net southerly flow due to its proximity to the
mouth of the Chesapeake Bay. Salinity ranges from 18 to 23 ppt.
EASTERN SHORE EMBAYMENTS:
EE1 Eastern Bay, Miles River, and Wye River
EE2 Choptank River, west of Castle Haven, including Tred
Avon River, Broad Creek, Harris Creek, and the Little
Choptank River
EE3 Tangier and Pocomoke Sounds
These three segments are characterized by salinity patterns similar
to the adjacent waters of the Chesapeake Bay. The water in these
areas is generally shallow enough to permit light penetration for
submerged aquatic vegetation growth and is strongly influenced by
wind patterns.
EASTERN SHORE TIDAL TRIBUTARIES:
ET1 Northeast River
ET2 Elk River and Bohemia River
ET3 Sassafras River
ET4 Chester River
ET5 Choptank River
ET6 Nanticoke River
ET7 Wicomico River
ET8 Manokin River
ET9 Big Annemessex River
ET10 Pocomoke River
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CBP SEGMENT DESIGNATION continued:
The ten segments in this group encompass the estuarine, or tidal,
reaches of the major Eastern Shore tributaries. They are
characterized by weak estuarine circulation patterns and limited
flushing capacities. Water quality in these segments is controlled
by the density structure of the mainstem Bay waters that are
adjacent to the tributaries mouths.
MAJOR TIDAL TRIBUTARIES OF THE WESTERN SHORE:
Patuxent River
Potomac River
Rappahannock River
York River
James River
Mobjack Bay
Elizabeth River
TF1
RET1
LEI
TF2
RET2
LE2
TF3
RETS
LE3
TF4
RET4
LE4
TF5
RETS
LE5
WE4
ELIZA
Tidal freshwater segment
Riverine-estuarine transition zone
Lower estuarine segment
Tidal freshwater segment
Riverine-estuarine transition zone
Lower estuarine segment
Tidal freshwater segment
Riverine-estuarine transition zone
Lower estuarine segment
Tidal freshwater segment
Riverine-estuarine transition zone
Lower estuarine segment
Tidal freshwater segment
Riverine-estuarine segment
Lower estuarine segment
The five major tidal tributaries along the middle to lower western
shore of the Chesapeake share common hydrodynamic and water quality
features.
The TF, or tidal freshwater, segments are located in the upper tidal
reaches of the tributaries where the water remains fresh year-round
because these areas are dominated by freshwater inflow. These areas
are the resident habitats of freshwater fish and are prime spawning
areas for anadromous and semi-anadromous fish.
The RET, or riverine-estuarine transition, segments are located in
the mid sections of these five tributaries. The freshwater inflow
mixes with the saltier Bay water brought in with the tide, and a
transition zone between freshwater and marine habitats is the
result. Salinities range from about 3 to 9 ppt. This zone is the
region of maximum turbidity due to suspended sediments which, for
most of the year, reduce the amount of light available for
phytoplankton. The transition zone tends to concentrate and trap
suspended particulate matter, some of which may contain toxic
chemicals which are adsorbed onto the sediment particles.
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CBP SEGMENT DESIGNATION continued:
The LE, or lower estuarine, segments are located between the RET
segments and the mainstem of the Chesapeake. They are characterized
by moderate salinity (7 to 13 ppt) and have two-layer estuarine
circulation driven by freshwater inflow. These segments are usually
the upstream limit of deep-water anoxia in the tributaries.
Segment WE4, Mobjack Bay, is located north of the mouth of the York
River. This segment is characterized by salinity patterns similar
to the adjacent waters of the Chesapeake Bay. The water in this
segment is generally shallow enough to permit light penetration for
submerged aquatic vegetation growth and is strongly influenced by
wind patterns.
The Elizabeth River, segment ELIZA, is a tributary of the James
River. Its physical characteristics are similar to those of the LE
segments. This segment was separated from the James River LE5
segment due to highly degraded water quality which skews statistical
data for the LE5 segment.
TIDAL TRIBUTARIES OF THE UPPER WESTERN SHORE:
WT1 Bush River
WT2 Gunpowder River
WT3 Middle River and Seneca Creek
WT4 Back River
WT5 Patapsco River
WT6 Magothy River
WT7 Severn River
WT8 South, Rhode, and West rivers
The WT, or western tributary, segments encompass the tidal reaches
of the small tributaries along the western shore of the Chesapeake
Bay north of the Patuxent River. These segments are characterized
by weak estuarine circulation patterns and limited flushing
capacities. Water quality in these segments is controlled by the
density structure of the mainstem of the Bay at the mouths of the
tributaries.
METHOD CHANGES:
None
Guide to Using CBP Water Quality Monitoring Data Page 31
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CBP SEGMENT DESIGNATION continued:
DAITS ISSUES:
None
OTHER ISSUES:
Other segmentation schemes have been developed for special
applications such as the Submerged Aquatic Vegetation (SAV) aerial
survey, the 3D model segments, and the Watershed Model segments.
Data presented in these special-purpose segments are converted to
the CBP segments before being added to the CBP data base.
OTHER DOCUMENTATION:
CBP 1983a, "Chesapeake Bay: A profile of environmental change," for
descriptions of each segment. Appendix A, Section 2, has the most
complete description.
CBP 1990, "The Chesapeake Bay Segmentation Scheme," for geographic
boundaries of the segments.
Guide to Using CBP Water Quality Monitoring Data Page 32
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TITLE: CRUISE IDENTIFIER
PARAMETER NAME: CRUISE
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
The data for a CRUISE is intended to denote a bay-wide synoptic view
of the Bay at one time. This parameter is useful for grouping data
collected over a range of sampling dates within the mainstem.
Cruises are numbered sequentially and begin with the letters "BAY,"
e.g. "BAYOOl" (June 1984) .
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
There may be gaps in the cruise sequence for individual stations
and/or agencies. These may be due to several reasons: stations are
sampled only during certain seasons; cruise (s) dropped by one
agency, but not by others; a cruise was displaced because of
weather.
In the tributary data sets, CRUISE contains the value most closely
related temporally to a mainstem cruise and also begins with the
letters "BAY." Since tributary and mainstem sampling dates often
vary by more than a week, the user should remember that combining
these data sets by CRUISE number will not necessarily produce the
same synoptic view as one would expect when using bay-wide data sets
for the same CRUISE.
OTHER DOCUMENTATION:
Refer to Chapter V, "Related Documentation."
3/93 Guide to Using CBP Water Quality Monitoring Data Page 33
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TITLE: DATE OF SAMPLE COLLECTION
PARAMETER NAME: DATE
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
DATE in the water quality data base is the date of sample collection
and is stored in SAS date format.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
DATE is a "key" sorting field when searching for a particular
observation in the data base. The parameter PERIOD could be used
when locating data temporally.
OTHER DOCUMENTATION:
Refer to "Identifier Variables - CRUISE and PERIOD," and to the "Data
Management Plan" (CBP 1992a).
Guide to Using CBP Water Quality Monitoring Data Page 34
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TITLE: SAMPLE LAYER
PARAMETER NAME: LAYER
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
Physical/chemical profiling of the water column is done at generally
regular depth intervals. Samples for water chemistry analyses are
collected at surface and bottom, and at stratified stations, at two
mid-water depths based on the presence and location of a pycnocline
(see "Pycnocline, Lower Depth" for a definition). LAYER codes
(S=surface, AP=above the pycnocline, BP=below the pycnocline, and
B=bottom) identify these samples. If samples are collected at 1/3
and 2/3 of the total depth, LAYER is coded as AP and BP
respectively. This is done to facilitate data retrieval by layer.
MD/MDE: During cruise BAY001 4 grab samples were collected at each
station. Since then, shallow stations are sampled only at surface
and bottom layers. Elsewhere, where a pycnocline exists, the above
pycnocline sample is collected 1.5 meters above the pycnocline, the
below pycnocline sample is collected 1.5 meters below the
pycnocline, and the bottom sample is collected 1-1.5 meters from the
bottom (see Table 1, "Mainstem Water Quality Monitoring Stations").
Where both an upper and lower pycnocline exist, then the above
pycnocline sample is collected above the upper pycnocline and the
below pycnocline sample is collected below the lower pycnocline. No
sample is collected from the intermediate zone. If no pycnocline
exists, then samples are collected at surface and bottom layers, and
at 1/3 and 2/3 total depth.
VA/VIMS: Specific stations are identified as "pycnocline" stations
and surface, above pycnocline, below pycnocline, and bottom water
chemistry samples are collected only at these stations. At other
stations, water chemistry samples are collected only from the
surface and bottom layers. There is no indication of presence or
depth of a pycnocline at other stations.
ODU: ODU has specified pycnocline stations where four water
chemistry samples are collected. During the early cruises, ODU did
not identify a lower pycnocline. Beginning with CRUISE BAY113, both
upper and lower pycnocline depths are always coded.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 35
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SAMPLE LAYER continued:
METHOD CHANGES:
MD/MDE: In the first year of the program (June through December
1984), the water chemistry samples were collected from whatever
depth was indicated by the pycnocline computation, regardless of
whether there had been physical/chemical measurements collected at
that depth. In MDE data from this period, if you retrieve the data
only from the data records containing the water chemistry
analyses, where LAYER is not blank, then data for dissolved oxygen,
salinity, water temperature, etc. may have been linearly
interpolated between the readings from above and below that depth.
Starting in 1985, the sampling protocol was changed so that water
chemistry samples are always associated with profile measurements.
VA/VIMS: Above pycnocline and below pycnocline samples were not
necessarily collected relative to the pycnocline depth as defined by
CBP methods (see "Pycnocline, Lower Depth," below). Also, early
VIMS data did not include layer codes, and these were assigned by
CBPCC staff using PDEPTHU values. In early VIMS data, therefore,
there may be more than one sample per layer code for a given station
and date (albeit at different depths); i.e., two above pycnocline
samples and no below pycnocline sample, or two below pycnocline
samples and no bottom sample. The variable SDEPTH must be included
to sort these records correctly (refer to DAITS #25).
VA/ODU: ODU has varied their sampling at 1/3, 2/3 and pycnocline
stations over the length of the program. During the early cruises
they did not sample above and below the pycnocline or sample at 1/3
or 2/3 of total depth. Later they took four samples only if there
was a pycnocline. Currently at three specified pycnocline stations,
they look for a pycnocline and sample above and below it if one
exists; if a pycnocline does not exist, they sample at 1/3 and 2/3
total depth.
DAITS ISSUES:
DAITS #25: There are differences in the way in which the various
collecting agencies determine pycnocline depth upper (PDEPTHU) and
pycnocline depth lower (PDEPTHL). The determination of these depths
affects the depth at which AP and BP will be sampled.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 36
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SAMPLE LAYER continued:
OTHER ISSUES:
Depending on the stratification characteristics of the water column,
S and AP, or B and BP samples (each collected separately) can occur
at the same sampling depth. This occurs mostly in the Maryland
portion of the Bay and at Virginia stations CB6.4, CB7.3, and CB7.4.
From June 1984 to December 1990, 164 observations had S and AP at
the same depth and 180 observations had B and BP at the same depth.
To sort records, sort by STATION, DATE, SDEPTH, LAYER, and REP_NUM.
The user must examine the conductivity profile in the data base to
see where no pycnocline exists but 1/3 and 2/3 samples were
collected. These 1/3, 2/3 samples will have LAYER coded as "AP" and
"BP" and PDEPTHU and PDEPTHL will be set to missing.
OTHER DOCUMENTATION:
Refer to "Identifier Variables - SDEPTH," and Chapter V, "Related
Documentation."
3/93 Guide to Using CBP Water Quality Monitoring Data Page 37
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TITLE: PERIOD OF SAMPLING
PARAMETER NAME: PERIOD
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
PERIOD is a parameter created in second-level data retrieval
software. It is a character parameter containing the first and last
dates for a cruise. For example, if MDE sampled between 8/12/92-
8/14/92, ODU sampled on 8/11/92 and VIMS sampled between 8/11/92-
8/12/92, PERIOD would contain the value "8/11/92-8/14/92." PERIOD
is selected from the menu when running the retrieval software and is
used in report or graphics titles to show the actual range of dates
for a particular cruise.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 38
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TITLE: PYCNOCLINE, LOWER DEPTH
PARAMETER NAME: PDEPTHL
UNITS OF MEASURE: Meters
METHOD CODES: None
GENERAL METHOD:
The monitoring program requires that at certain stations, two mid-
water nutrient samples be collected relative to the pycnocline.
These are listed in Table 1 with a "4" in the "Number Samples"
column. The pycnocline is the region of the water column where
density changes rapidly due to salinity and temperature differences.
Since the pycnocline is often a region of mixing of water masses,
the goal is to sample above and below this layer to characterize the
separate upper and lower water masses. The top and bottom of the
pycnocline region is identified in the CBP data base by PDEPTHU and
PDEPTHL (pycnocline depth upper and lower). Identifying these
depths enables determination of the sampling depth for nutrients at
above and below the pycnocline (AP and BP).
The presence and location of a pycnocline is determined from the
conductivity profile. A computed threshold value (CTV) is
calculated from 2 times the mean change in conductivity per meter
between the surface and bottom. If the CTV exceeds 500 micromhos/cm
per meter, a pycnocline is assumed to exist, and the lower
pycnocline depth is usually defined at the first depth interval from
the bottom (or from the surface for the upper pycnocline depth) with
a change in conductivity that exceeds the CTV. See below for
details of the method used by each collecting organization.
Where a pycnocline exists, the above pycnocline (AP) sample is
usually collected 1.5 meters above the upper pycnocline depth, and
the below pycnocline (BP) sample is usually collected 1.5 meters
below the lower pycnocline depth.
MD/MDE: MDE averages the two sample depths in which the difference
in conductivity exceeds the computed threshold value (CTV). For
PDEPTHU these values are the first pair from the surface and for
PDEPTHL the first pair from the bottom that exceed the CTV.
VA/ODU: ODU assigns the value of PDEPTHU to the shallower of the
two sample depths that exceed the CTV (not the average). ODU sets
the value of PDEPTHL similar to MDE, except the value is the deeper
of the two sample depths.
VA/VIMS: VIMS assigns the value of PDEPTHU to the shallower of the
two sample depths that exceed the CTV (not the average). Because
they use a different method to define the pycnocline, in VIMS data
PDEPTHL is equal to PDEPTHU.
Guide to Using CBP Water Quality Monitoring Data Page 39
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PYCNOCLINE, LOWER DEPTH continued:
METHOD CHANGES:
Refer to "Identifier Variables - LAYER."
DAITS ISSUES:
DAITS #25: There are differences in the way in which the various
collecting agencies determine pycnocline depth upper (PDEPTHU) and
pycnocline depth lower (PDEPTHL). The determination of these depths
affects the depth at which AP and BP will be sampled.
OTHER ISSUES:
Refer to "Identifier Variables - LAYER."
If no pycnocline was indicated and sampling occurred at 1/3 and 2/3
of total depth, PDEPTHU and PDEPTHL are set to missing in the data
base. The LAYER parameter is coded AP and BP, to facilitate data
retrieval by layer.
OTHER DOCUMENTATION:
See "Identifier Variables - SDEPTH and LAYER," Chapter V, "Related
Documentation," and the "Data Management Plan" (CBP 1992a).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 40
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TITLE: PYCNOCLINE, UPPER DEPTH
PARAMETER NAME: PDEPTHU
UNITS OF MEASURE: Meters
METHOD CODES: None
GENERAL METHOD:
Refer to "Identifier Variables - PDEPTHL."
METHOD CHANGES:
Refer to "Identifier Variables - LAYER."
DAITS ISSUES:
DAITS #25: There are differences in the way in which the various
collecting agencies determine pycnocline depth upper (PDEPTHU) and
pycnocline depth lower (PDEPTHL). The determination of these depths
affects the depth at which AP and BP will be sampled.
OTHER ISSUES:
Refer to "Identifier Variables - LAYER."
If no pycnocline was indicated and sampling occurred at 1/3 and 2/3
of total depth, PDEPTHU and PDEPTHL are set to missing in the data
base. The LAYER parameter is coded AP and BP, to facilitate data
retrieval by layer.
OTHER DOCUMENTATION:
See "Identifier Variables - PDEPTHL, SDEPTH, and LAYER," Chapter V,
"Related Documentation," and the "Data Management Plan" (CBP 1992a) .
3/93 Guide to Using CBP Water Quality Monitoring Data Page 41
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TITLE: REPLICATE NUMBER
PARAMETER NAME: REP_NDM
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
REP_NUM in monitoring data sets represents the field replicate
number. These may represent field splits from a single sample (MDE
and VIMS) or true field replicates (two successive grab samples,
ODU) .
MD/MDE: Ten percent of water samples collected in the field are
split for duplicate analysis (the whole suite of laboratory analyses
are duplicated). Specific stations and layers with field replicates
are: CB1.1-B, CB2.2-S, CB3.3C - B, CB4.1W - S, CB4.2E - B, CB4.3C -
AP, CB4.4 - B, and CBS.2 - S. See DAITS #3 for more details. Both
split sample results are reported in the regular monitoring data
base (REP_NUM=1 or 2).
VA/ODU: Field replicates from station CB7.3 or CB7.4N, collected as
two successive grab samples, have been submitted since June 1984 and
are coded in regular monitoring data as REP_NUM=1 or 2.
VA/VIMS: The means of two field splits, but not the two separate
values, are included in the monitoring data base beginning with
Cruise 96 (the first cruise in April 1989) . Thus, the variable
REP_NUM is always set to 1 in VIMS monitoring data. The
concentration of one of the field splits, and their standard
deviation, are in the QA data set, identified by REP_TYPE = "FLD".
Data users can calculate the concentration of the other split sample
using this value and the mean in the monitoring data set.
METHOD CHANGES:
None
DAITS ISSUES:
DAITS #3: See this issue for more details on field replicate
methods.
OTHER ISSUES:
None
OTHER DOCUMENTATION:
Refer to Chapter IV, "Quality Assurance (QA) Data."
3/93
Guide to Using CBP Water Quality Monitoring Data Page 42
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TITLE: SAMPLE DEPTH
PARAMETER NAME: SDEPTH
UNITS OF MEASURE: Meters
METHOD CODES: None
GENERAL METHOD:
MD/MDE: At the beginning of the program (June 1984 through April
1986), physical/chemical profiles were collected at every meter,
beginning with 0.5 meter, and continuing until there was little
change in temperature, salinity, or dissolved oxygen. Thereafter
physical/chemical measurements were collected every 3 meters to the
bottom.
VA/ODU: ODD takes profile samples at 1-meter intervals, beginning
with 1 meter up to 15 meters and then every 2 meters to the bottom.
VA/VIMS: During the first cruise, June 1984, the physical/ chemical
profile began at 2 meters and measurements were collected every 2
meters to the bottom.
METHOD CHANGES:
MD/MDE: The protocol was modified in May 1986 and measurements were
recorded at 0.5, 1, and 3 meters and thereafter at 2-meter inter-
vals. If dissolved oxygen concentration changed more than l mg/1
over the interval, or conductivity changed more than 1000 umhos/cm,
then readings were taken at 1-meter intervals.
VA/VIMS: From July 1984-July 1986, the surface layer sample was at
1 meter and successive samples were taken at 2-meter intervals.
From August 1986-June 14, 1987, the surface was at 1 meter, then
samples were taken every 1 meter down to 15 meters, and every 2
meters below that. Starting June 15, 1987, a profiling CTD took
readings for all parameters except DO every 1 meter from 1 meter
depth to the bottom; the protocol for DO did not change, since VIMS
staff measure DO with a YSI meter.
DAITS ISSUES:
None
OTHER ISSUES:
SDEPTH = 0 in the data base header record is reserved for station
information such as secchi depth readings, tide stage, weather, air
temperature, etc., at the time the station is sampled.
OTHER DOCUMENTATION:
Refer to "Identifier Variables - Layer," Chapter V, "Related
Documentation," and the "Data Management Plan" (CBP I992a).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 43
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TITLE: TOTAL DEPTH
PARAMETER NAME: TDEPTH
UNITS OF MEASURE: Meters
METHOD CODES: None
GENERAL METHOD:
Total Depth represents the measured water depth at the station. It
should be greater than any sample depths, since the "bottom" sample
is always taken slightly above the actual bottom. Total Depth will
vary slightly at the same station over time because of changes in
tidal stage and exact sampling location.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 44
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TITLE: SAMPLING STATION IDENTIFIER
PARAMETER NAME: STATION
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
All of the mainstem data submitters locate their stations using
Loran-C. MDE holds the station by anchor if required by weather or
currents, VIMS holds the station by anchor, and ODU positions the
vessel to drift through the station area.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
The submitter's station name is not kept in the data base. If
needed, the user should refer to the "Chesapeake Bay Basin
Monitoring Program Atlas" (CBP 1989) for lists of the submitter's
station names.
The shallow stations in the uppermost part of the Bay (Stations
CB1.1 and CB2.1) may be ice-covered during some part of the winter.
Data gaps are common during those months.
As a cost-saving measure, beginning in fall 1988, the lateral
stations in the MD portion of the Bay (CB3.3E, CB3.3W, CB4.1E,
CB4.1W, CB4.2E, CB4.2W, CB4.3E, and CB4.3W) are not sampled from
November through the first cruise in March.
To monitor the effect of dumping dredge spoil in the deep trench,
the Maryland Port Authority funded an additional transect of
stations (CB4.0E, CB4.0C, and CB4.0W) within the Monitoring Program
sampling design. These stations were sampled from June through
September 1990. CB4.0C is the only station where nutrient samples
were collected.
VIMS and MDE both sampled CB5.3 until April 1990. Due to the
frequency of sampling variations, this was discontinued and VIMS no
longer samples this station. To avoid confusion caused by having
the same station duplicated, the VIMS data were removed from the
data base, but is available upon request.
Guide to Using CBP Water Quality Monitoring Data Page 45
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SAMPLING STATION IDENTIFIER continued:
OTHER DOCUMENTATION:
Refer to Table 1, "Mainstem Water Quality Monitoring Stations" and
the "Chesapeake Bay Monitoring Program Atlas" (CBP 1989).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 46
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TITLE: SOURCE AGENCY
VARIABLE NAME: SOURCE
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
Valid codes for SOURCE in the mainstem data sets are "MD/MDE" (was
"MD/OEP" till 1987), "VA/ODU", and "VA/VIMS".
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
SOURCE does not identify the analysis laboratories. In Maryland,
Central Regional Laboratory (CRL), Chesapeake Biological Laboratory
(CBL), and Maryland Department of Health and Mental Hygiene (MDHMH)
all have the same source. It usually identifies the field sampling
agency, although it may not in some tributary data.
OTHER DOCUMENTATION:
Refer to the "Data Management Plan" (CBP I992a).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 47
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TITLE: SAMPLING TIME
PARAMETER NAME: TIME
UNITS OF MEASURE: HHMM
METHOD CODES: None
GENERAL METHOD:
Sampling time is coded using the 2400 clock, and should be Eastern
Standard Time (EST) , according to the Data Management Plan (CBP
1992a) . In the CBP data base, it is a numeric variable ranging from
0 to 2400. VIMS submits TIME as EST, but MDE and ODU submit it as
local time (EST or EDT depending on the date).
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
Refer to the "Data Management Plan" (CBP I992a).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 48
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C. Water Quality Parameters
This summary of general information about each parameter measured or
calculated is intended to make data analysts aware of special problems
they may encounter when analyzing each parameter. These include method
changes, Data Analysis Issues Tracking System (DAITS) issues, and problems
with inter-organization agreement.
Laboratory methods are indicated by method codes carried either as
variables in the data set (parameter_M) or in the data set documentation.
A detailed description of the methods and any slight variations of the
methods used by the Program participants is available on line in CHESSEE
(CHESSEE, Documentation, MEthods), although this information is not
currently up to date (as of August 1992).
Variable names for monitored parameters usually imply similar analytical
methods and units of measure. However, some variables have been named to
correspond to variable names in the historical water quality data base.
For example, particulate carbon is called POC, not PC; and particulate
nitrogen is called PON, not PN. The results of particulate carbon and
nitrogen analyses using an elemental analyzer may contain some inorganic
carbon or nitrogen, but the results are called POC and PON to agree with
the name of the previous mainstem methods.
The Data Analysis Issues Tracking System (DAITS) is used to collect
information and achieve consensus on analytical and other issues affecting
data analysis. Brief summaries of completed issues are listed here.
Contact CBP computer center (CBPCC) staff for more information.
See Chapter V, "Related Documentation" for other documentation.
Guide to Using CBP Water Quality Monitoring Data Page 49
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TITLE: PHYSICAL PROFILE SAMPLING METHODS
PARAMETER NAME: None
(applied to COND, DISOXY, PH, SALIN, and WTEMP)
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHOD:
MD/MDE and VA/ODU: Both agencies currently use a Hydrolab probe
attached to the sampling pump. The probe is lowered in discrete
increments and the suite of readings is copied by hand to field
sheets.
VA/VIMS: VIMS currently uses a CTD for conductivity (COND) and
water temperature (WTEMP) and a YSI meter for dissolved oxygen
(DISOXY). The CTD and YSI assembly is lowered at a constant rate
and both are attached to the sampling pump. Measurements from the
CTD are captured electronically every two seconds. Values reported
to the CBPO are averages of the values (typically 3 to 4) which fall
within that meter. The value reported at an SDEPTH of 1.0
represents the readings from 0.5 to 1.5 meters. Values have been
reported on the station information record (SDEPTH = 0) . These
values are the average of the measurements recorded from the time
the probe hits the water to 0.5 meters. Measurements from the YSI
are hand written on field sheets at discrete sample depths. Later
the dissolved oxygen values are corrected for water temperature and
conductivity. VIMS does not measure pH as part of the vertical
profile, it is measured only from the nutrient samples on board the
research vessel.
METHOD CHANGES:
VIMS currently uses an Applied Microsystems CTD, and previously used
an Interoceans CTD. They have always used a YSI meter for dissolved
oxygen.
Originally, MDE and ODU lowered the Hydrolab separately from the
sample collection pump. MDE started attaching the Hydrolab probe to
the sampling pump and lowering them together on 1/1/89, and ODU made
this change on 8/21/91. MDE also lowered the probe and pump
separately for several months starting in 1/90 when faulty
electrical wiring in the pump interfered with operation of the
Hydrolab. Once the wiring was repaired, they were lowered together
again.
DAITS ISSUES:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 50
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PHYSICAL PROFILE SAMPLING METHODS continued:
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
Guide to Using CBP Water Quality Monitoring Data Page 51
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TITLE: DISSOLVED OXYGEN
PARAMETER NAME: DISOXY
UNITS OF MEASURE: mg/1
METHOD CODES: See CHESSEE list
GENERAL METHOD:
MD/MDE: MDE validates the Hydrolab's dissolved oxygen measurements
by performing Winkler dissolved oxygen titrations on three samples
pulled from a bucket with the Hydrolab. This is done once each day
during the cruise. The Winkler validation numbers are recorded on
the field sheets but are not submitted to the CBPO as separate
parameters. Meter results should be within 0.5 mg/1 of Winkler
results, and a different Hydrolab is used if they can't be brought
closer.
YA/ODU: ODU submits two dissolved oxygen variables, DISOXY and
DISOX2, with the water quality data. The variable DISOXY contains
the Hydrolab's measurement. The variable DISOX2 contains the
Winkler titrated value. DISOXY values are maintained in both levels
of the data base, and DISOX2 is available upon request.
VA/VIMS: VIMS reports three dissolved oxygen variables with the
water quality data, DISOXY, DISOX2, and DISOX3. The variable DISOX2
contains the 'raw' YSI reading, and DISOXY contains the YSI reading
corrected for water temperature and conductivity. The variable
DISOX3 has the Winkler titrated value, which is done at each sample
depth that has a nutrient sample (2 or 4 samples depending on the
station). The variables DISOX2 and DISOX3 are available upon
request.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 52
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TITLE: DISSOLVED OXYGEN SATURATION
PARAMETER NAME: DO_SAT
UNITS OF MEASURE: mg/1
METHOD CODES: See CHESSEE list
GENERAL METHOD:
DO_SAT is a calculated value representing the dissolved oxygen
concentration at saturation for that water temperature and salinity.
This is calculated from an equation provided by Hydroqual:
DO_SAT = 14.6244 - 0.367134*WTEMP + 0.0044972*WTEMP*WTEMP
- 0.0966*SALIN + 0.00205*SALIN*WTEMP + 0.0002739*SALIN*SALIN;
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
Guide to Using CBP Water Quality Monitoring Data Page 53
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TITLE: PH
PARAMETER NAME: PH
UNITS OF MEASURE: Standard units
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Refer to "Dissolved Oxygen" for physical profile methods.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
VIMS does not measure pH as part of the vertical profile. They
collect aliquots of the nutrient samples and measure pH onboard the
research vessel with a pH meter.
OTHER DOCUMENTATION:
None
Guide to Using CBP Water Quality Monitoring Data Page 54
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TITLE: SALINITY
PARAMETER NAME: SALIN
UNITS OF MEASURE: ppt
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Refer to "Dissolved Oxygen" for physical profile methods.
The salinity value is either computed from conductivity (COND) and
water temperature (WTEMP) when using a CTD, or read directly when
using a Hydrolab.
VA/VIMS: VIMS compares its CTD salinity measurements with a Beckman
Salinometer and submits these values as the variable SALIN2. VIMS
uses the UNESCO equation for calculating the CTD measured salinity.
SALIN2 is available upon request.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 55
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TITLE: SECCHI DISK DEPTH
PARAMETER NAME: SECCHI
UNITS OF MEASURE: Meters
METHOD CODES: See CHESSEE list
GENERAL METHOD:
A black-and-white Secchi disk attached to a ruled line is lowered
into the water. The depth at which the disk disappears is averaged
with the depth at which it reappears; this measurement (in meters)
is the Secchi depth (SECCHI).
METHOD CHANGES:
The disk may be either 20 or 30 cm wide.
DAITS ISSUES:
DAITS #7: Secchi variability and time of sampling are discussed.
OTHER ISSUES:
SECCHI_D may be ">" if the disk is lowered to the bottom without
disappearing from view.
The value for SECCHI is sometimes missing due to the time of day the
station was sampled (see DAITS #7 for details) . SECCHI is only
taken within 1/2 hour before to 1/2 hour after sunrise and sunset
respectively.
SECCHI should only be reported on the station information record
where SDEPTH = 0.
OTHER DOCUMENTATION:
None
Guide to Using CBP Water Quality Monitoring Data Page 56
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TITLE: SPECIFIC CONDUCTIVITY
PARAMETER NAME: COND
UNITS OF MEASURE: umhos/cm
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Refer to "Dissolved Oxygen" for physical profile methods.
METHOD CHANGES:
ODU submitted COND as mmhos/cm until March 1992, when they started
sending it as umhos/cm.
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 57
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TITLE: WATER TEMPERATURE
PARAMETER NAME: WTEMP
UNITS OF MEASURE: degrees Celsius
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Refer to "Dissolved Oxygen" for physical profile methods. A
thermistor is used, in a Hydrolab (MDE and ODU) or CTD (VIMS). It
cannot be calibrated in the Hydrolab; the unit must be sent in for
service if out of. calibration. MDE and ODU check the temperature
calibration of the Hydrolab thermistor against a NIST calibrated
thermometer at least twice a year.
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 58
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TITLE: SPECIFIC GRAVITY
PARAMETER NAME: SIG_T
UNITS OF MEASURE: none
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Specific gravity is calculated from:
sigo=-0.069+((1.47808*((salin-0.03)/I.805))
- (0.00157* (((salin-0.03}/I.805}**2))
+(0.0000398*(((salin-0.03)/I.805)**3)));
tsum=(-l*(((wtemp-3.98)**2)/503.57))*((wtemp+283)/(wtemp+67.26));
sa=((10**-3)*wtemp)*(4.7867-(0.098185*wtemp)+(0.0010843*
(wtemp**2))) ;
sb=((10**-6)*wtemp)*(18.030-(0.8164*wtemp)+(0.01667*(wtemp**2)));
SIG_T = tsum+( (sigo+0.1324) * (1-sa+sb* (sigo-0 .1324)) ) ;
METHOD CHANGES:
None
DAITS ISSUES:
None
OTHER ISSUES:
None
OTHER DOCUMENTATION:
None
3/93
Guide to Using GBP Water Quality Monitoring Data Page 59
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TITLE: FIELD FILTRATION METHODS
PARAMETER NAME: None (affects all dissolved and particulate
parameters)
UNITS OF MEASURE: None
METHOD CODES: None
GENERAL METHODS:
All dissolved parameters are analyzed from water filtered in the
field, to minimize changes in the sample caused by biological
activity after sample collection. All parameters are filtered using
a vacuum pump, except DOC/POC/PON filtration at ODU used positive
pressure filtration with a syringe until 1992. Whether or not the
filter was rinsed after filtration also varied: TSS/PHOSP filters
are always rinsed with deionized (DI) water, because the salt
prevents accurate TSS determination if the filter is unrinsed.
POC/PON filters were rinsed by VIMS with DI water until 1992, but
were never rinsed by ODU or MDE field crews. CHLA filters have
magnesium carbonate added at all mainstem laboratories.
The filtrate used for dissolved nutrient analysis varies: MDE/CBL
uses the POC/PON filtrate, while ODU and VIMS use the TSS/PHOSP
filtrate, removing it from the filter apparatus before the TSS/PHOSP
filter is rinsed with DI water. The filtrate used for DOC also
varies: CBL and ODU use the POC/PON filtrate for DOC analyses, while
VIMS uses the TSS/PHOSP filtrate for DOC.
METHOD CHANGES:
MDE and VIMS field crews used 0.45 micron membrane filters at the
start of the program in June 1984. ODU field crews have used 0.7
micron glass fiber filters (Whatman GF/F, except for CHLA and
POC/PON) since the start of the program. VIMS changed to 0.7 micron
glass fiber filters in June 1985, and MDE crews made this change on
May 15, 1985. A study by Magnien (1986) showed there were no
statistically significant differences in any dissolved parameters
filtered by the two methods, except for small differences in silica
concentrations.
The change in filter type was made for two reasons: membrane filters
tend to clog when TSS is high, and there are possible contamination
problems with nutrients released by the membrane filter.
VIMS previously used the POC/PON filtrate for DOC, but switched to
using the TSS/PHOSP filtrate when they had contamination problems.
DAITS ISSUES:
DAITS #23: Effects of filter rinsing on POC/PON results are
discussed. Results pending, data being collected by VIMS. Contact
Betty Salley for more information.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 60
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FIELD FILTRATION METHODS continued:
OTHER ISSUES:
VIMS and ODD used Gelman AE glass fiber filters for their POC/PON
determinations, because Whatman GF/F were not available in the
diameter they needed. Both now use Whatman GF/F.
ODU used Whatman GF/C filters for CHLA filtration until 1992, when
they switched to Whatman GF/F. GF/C has slightly larger pore size
(1.0 micron). ODU ground CHLA filters on the boat, unless seas were
too rough; ODU started grinding in the laboratory in 1992 . MDE and
VIMS grind CHLA filters in the laboratory.
OTHER DOCUMENTATION:
"A comparison of estuarine water chemistry analysis on the filtrate
from two types of filters" (Magnien 1986) .
"Estuarine nutrient analyses: A comparison of sample handling
techniques and analyses of carbon, nitrogen, phosphorus, and
chlorophyll a" (Zimmermann 1991).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 61
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TITLE: TOTAL PHOSPHORUS
PARAMETER NAME: TP
UNITS OF MEASURE: mg/1 as P
METHOD CODES: See CHESSES list
GENERAL METHODS:
Direct: An unfiltered water sample is digested in acid and
persulfate to convert all forms of phosphorus to orthophosphate.
Then orthophosphate is determined with the autoanalyzer.
Calculated: TOP + PHOSP (see those parameters for details).
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" in Chapter III for dates that each
method was used at each laboratory. The change to TP calculated was
made to eliminate any parameters calculated by subtraction, since
calculations by subtraction were shown to be less accurate and can
yield negative values (see D'Elia et al. 1987) . No step trends have
been identified associated with these method changes.
DAITS ISSUES:
DAITS #10: Summarizes method comparison data available to document
comparability of old and new TP methods.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992) .
OTHER DOCUMENTATION:
"Chesapeake Bay Coordinated Split Sample Program Annual Report,
1990-1991" (AMQAW 1992).
"Trends in Phosphorus in the Chesapeake Bay (1984-1990)" (CSC 1991).
"Nitrogen and phosphorus determinations in estuarine waters: a
comparison of methods used in Chesapeake Bay Monitoring" (D'Elia et
al. 1987).
Guide to Using CBP Water Quality Monitoring Data Page 62
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TITLE: TOTAL DISSOLVED PHOSPHORUS
PARAMETER NAME: TDP
UNITS OF MEASURE: mg/1 as P
METHOD CODES: See CHESSEE list
GENERAL METHOD:
All laboratories digest a filtered sample to convert all forms of
dissolved phosphorus to inorganic phosphorus (PO4F), which is
analyzed using with the same autoanalyzer manifold as PO4F. ODU
calibrates by the method of standard additions, using standards
diluted in a composite of water from several samples.
METHOD CHANGES:
No major method changes. Minor changes occurred in the digestion
method used {acid or alkaline persulfate). See Table 4, "Measured
and Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. Comparisons between results from the two
digestion methods showed slightly higher results with acid
persulfate, but the magnitude of the differences was fairly small
(about 0.005 mg/1, see Figure 15 in D'Elia et al. 1987).
DAITS ISSUES:
None
OTHER ISSUES:
Inter-laboratory agreement among the three mainstem laboratories
(CBL, VIMS, and ODU) is high for TDP, based on Coordinated Split
Sample Program (CSSP) data (AMQAW 1992) .
Sometimes TDP results are less than PO4F results, even though
theoretically they should be equal to or grater than PO4F. The
discrepancy may have two causes: TDP involves a digestion and P04F
does not, and material may be lost during digestion; TDP also
involves an internal dilution, and P04F does not. When TDP < PO4F,
laboratories should use analytical problem code 'QQ' and leave both
values in the data base if the discrepancy is less than the
analytical precision, usually estimated by the sum of both MDLs. If
the discrepancy is larger than the summed MDLs, one or both values
may be deleted.
OTHER DOCUMENTATION:
"Chesapeake Bay Coordinated Split Sample Program Annual Report,
1990-1991" (AMQAW 1992).
"Nitrogen and phosphorus determinations in estuarine waters: a
comparison of methods used in Chesapeake Bay Monitoring" (D'Elia et
al. 1987).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 63
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TITLE: PARTICDLATE PHOSPHORUS
PARAMETER NAME: PHOSP
UNITS OF MEASURE: mg/1 as P
METHOD CODES: See CHESSEE list
GENERAL METHODS:
Calculated: From TP - TDP.
Direct: The same filter weighed for TSS determination is used in
direct determination of PHOSP. After weighing, the filter is placed
in a crucible and heated in a muffle furnace at 550 C. The
combustion breaks down organically bound phosphorus to inorganic
phosphorus (orthophosphate), which is extracted with hydrochloric
acid and determined with an autoanalyzer. The method is from Aspila
et al. (1976).
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. The change to PHOSP measured directly was
made to avoid having to calculate any parameters by subtraction,
since calculations by subtraction were shown to be less accurate and
can yield negative values (see D'Elia et al. 1987). No step trends
have been identified associated with these method changes.
DAITS ISSUES:
DAITS #10: Summarizes method comparison data available to document
comparability of old and new PHOSP methods.
DAITS #16: If Maryland mainstem data is being combined with
Maryland tributary data for PHOSP, the differences found in TP and
TDP results from Maryland mainstem and Maryland tributary monitoring
programs probably also affected PHOSP. See TP or TDP for details.
OTHER ISSUES:
PHOSP may show a positive correlation with TSS, since it is
contained in plankton and it may adhere to soil particles. These
parameters can be compared when examining possible outliers in the
data.
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 64
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PARTICDLATE PHOSPHORUS continued:
OTHER DOCUMENTATION:
"Chesapeake Bay Coordinated Split Sample Program Annual Report,
1990-1991" (AMQAW 1992).
"Nitrogen and phosphorus determinations in estuarine waters: a
comparison of methods used in Chesapeake Bay Monitoring" (D'Elia et
al. 1987).
"A semi-automated method for the determination of inorganic,
organic, and total phosphate in sediments" (Aspila, I. et al. 1976).
3/93
Guide to Using CBP Water Quality Monitoring Data Page 65
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TITLE: ORTHOPHOSPHATE (FILTERED) AND DISSOLVED INORGANIC
PHOSPHORUS
PARAMETER NAME: PO4F and DIP
UNITS OF MEASURE: mg/1 as P
METHOD CODES: See CHESSEE list
GENERAL METHOD:
All laboratories use variants of EPA method 365, ascorbic acid
reduction, with an autoanalyzer, except ODU used a manual method
until 1992. ODU calibrates by the method of standard additions,
using standards diluted in a. composite of sample water. CBL and
VIMS use a double reagent method (ascorbic acid as a separate
reagent); see Zimmermann (1991) .
METHOD CHANGES:
ODU changed from manual to autoanalyzer method in 1992.
DAITS ISSUES:
DAITS #15: CBL revised their PO4F data with a salinity correction
in 1992. Correcting the CBP data base is pending, 7/31/92. This
did not affect other phosphorus parameters, although they are
analyzed as PO4F after digestion, because the additional reagents
used for TP, TOP, and PHOSP change the refractive index of the
solution and eliminate the need for the correction.
OTHER ISSUES:
Orthophosphate (filtered) is considered equivalent to dissolved
inorganic phosphorus (DIP). PO4F may include a small amount of
organic P, and it does not include one form of inorganic P, called
"hydrolyzable phosphate." The magnitude of these two components in
Bay P04F samples is unknown, but both are assumed to be small.
Hydrolyzable phosphate is mainly found in detergents, and its use is
now banned in most detergents. Hydrolyzable phosphate should be
included in TOP and TP determinations, however. PO4F is exactly
equivalent to Soluble Reactive Phosphorus (SRP) used in
oceanographic research.
Orthophosphate (filtered) is released (mineralized) from sediments
under anoxic conditions, which usually occur in the summer. Thus,
maximum values are often found in summer bottom samples.
A habitat requirement for Submerged Aquatic Vegetation (SAV) growth
has been established for DIP. April-October median surface values
should be less than 0.01 mg/1 in lower salinity regions, and less
than 0.02 mg/1 in higher salinity regions (>18 ppt). See Batiuk et
al. (1992) for details.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 66
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ORTHOPHOSPHATE (FILTERED) AND DISSOLVED INORGANIC PHOSPHORUS continued:
Orthophosphate (filtered) values are sometimes below the detection
limit, complicating trend analyses. Orthophosphate (filtered)
values may exceed TDP values; see TDP for more information.
In some historical Chesapeake Bay data (before 1984), PO4F may have
been reported as mg/1 P04 instead of as mg/1 P. All concentrations
should have been converted, but if high results are found for a
particular time period, they may have been reported as P04.
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992).
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
CSC. 1991. Trends in Phosphorus in the Chesapeake Bay (1984-1990).
CBP/TRS 67/91, Chesapeake Bay Program, Annapolis, MD.
Batiuk et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation
Habitat Requirements and Restoration Goals: A Technical Synthesis.
CBP/TRS 52/92, Chesapeake Bay Program, Annapolis, MD.
Zimmermann, C. 1991. Estuarine nutrient analyses: A comparison of
sample handling techniques and analyses of carbon, nitrogen,
phosphorus, and chlorophyll a. Report submitted to EPA through
Technology Applications, Inc. by Chesapeake Biological Laboratory,
Solomons, MD.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 67
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TITLE: DISSOLVED ORGANIC PHOSPHORUS
PARAMETER NAME: OOP
UNITS OF MEASURE: mg/1 as P
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Calculated from TOP - P04F for all laboratories and time periods,
assuming P04F = DIP.
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
Because Orthophosphate (filtered) (P04F) may include a small amount
of organic P, the calculation method used may underestimate DOP
slightly. However, DOP calculated by this method may be slightly
overestimated if hydrolyzable phosphate is present.
DOP can be negative, since PO4F sometimes exceeds TOP. It should be
set to 0 when negative.
OTHER DOCUMENTATION:
None
Guide to Using CBP Water Quality Monitoring Data Page 68
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TITLE: TOTAL NITROGEN
PARAMETER NAME: TN
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Total nitrogen is always calculated, from either TKNW + NO23 or TDN
+ PON.
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. The change to TN = TDN + PON was made to
avoid having to calculate any parameters by subtraction, since
calculations by subtraction were shown to be less accurate and often
yield negative values (see D'Elia et al. 1987) . Two step trends
have been identified associated with these method changes (see DAITS
issues); TN data in the CBP data base have been adjusted to correct
for both step trends.
DAITS ISSUES:
DAITS #2: Adjusting helix Kjeldahl nitrogen data (see Bergstrom
1992). Used method comparison data to correct a low bias in early
TKNW and TKNF data from OEP/CRL, and thus TN and TDN data.
DAITS #10: Summarizes method comparison data available to document
comparability of old and new TN methods.
DAITS #20: Adjustment for ODU TN Kjeldahl data. Used dummy
variables from TN regression to adjust ODU TN data; no adjustment
made to TKNW data.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories was fairly
low, based on CSSP data (AMQAW 1992). The difference was probably
due to the difference in PON results, since it followed the same
pattern; see PON for details.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Guide to Using CBP Water Quality Monitoring Data Page 69
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TOTAL NITROGEN continued:
Bergstrom, P. 1992. Adjusting helix Kjeldahl nitrogen results:
Maryland Chesapeake Bay Mainstem Water Quality Monitoring Program,
1984-1985. CBP/TRS 44/92, Chesapeake Bay Program, Annapolis, MD.
Chesapeake Bay Program (CBP). 1992. Trends in Nitrogen in the
Chesapeake Bay (1984-1990). CBP/TRS 68/92, Chesapeake Bay Program,
Annapolis, MD.
D'Elia, C. et al. 1987. Nitrogen and phosphorus determinations in
estuarine waters: a comparison of methods used in Chesapeake Bay
Monitoring. CBP/TRS 7/87, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 70
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TITLE: TOTAL DISSOLVED NITROGEN
PARAMETER NAME: TDN
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Calculated: from TDN = TKNF + NO23.
Direct: All laboratories digest a filtered sample with alkaline
persulfate to convert all forms of dissolved nitrogen to nitrite +
nitrate (N023), which is analyzed with the same autoanalyzer
manifold as NO23. See D'Elia et al. (1987) .
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. The change to TDN direct was made to avoid
having to calculate any parameters by subtraction, since
calculations by subtraction were shown to be less accurate and could
yield negative values (see D'Elia et al. 1987). Two step trends
have been identified associated with these method changes (see DAITS
issues) ; TDN data in the CBP data base have been adjusted to correct
for one step trend (see DAITS issues and Bergstrom 1992) .
DAITS ISSUES:
DAITS #2: Adjusting helix Kjeldahl nitrogen data (see Bergstrom
1992). Used method comparison data to correct a low bias in early
TKNW and TKNF data from OEP/CRL, and thus TDN data.
DAITS #10: Summarizes method comparison data available to document
comparability of old and new TDN methods.
DAITS #20: Adjustment for ODU TN Kjeldahl data. Used dummy
variables from TN regression to adjust ODU TN data; no adjustment
done to TKNF or TDN data.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories is
generally high, based on CSSP data (AMQAW 1992).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 71
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TOTAL DISSOLVED NITROGEN continued:
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Bergstrom, P. 1992. Adjusting helix Kjeldahl nitrogen results:
Maryland Chesapeake Bay Mainstem Water Quality Monitoring Program,
1984-1985. CBP/TRS 44/92, Chesapeake Bay Program, Annapolis, MD.
D'Elia, C. et al. 1987. Nitrogen and phosphorus determinations in
estuarine waters: a comparison of methods used in Chesapeake Bay
Monitoring. CBP/TRS 7/87, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 72
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TITLE: PARTICULATE ORGANIC NITROGEN and PARTICULATE NITROGEN
PARAMETER NAME: PON
UNITS OP MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Calculated: from PON = TKNW - TKNF.
Direct: All laboratories determine from a separate filter that is
combusted at 975-1050 C using an elemental analyzer. The results
may include some inorganic nitrogen, but the parameter is still
called PON in the CBP data base, not PN, to agree with the name for
the calculated method. See D'Elia et al. (1987).
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. The change to PON direct was made to avoid
having to calculate any parameters by subtraction, since
calculations by subtraction were shown to be less accurate and could
yield negative values (see D'Elia et al. 1987). Two step trends
have been identified associated with these method changes (see DAITS
issues) ; PON data in the CBP data base have been adjusted to correct
for one step trend (see below).
DAITS ISSUES:
DAITS #2: Adjusting helix Kjeldahl nitrogen data (see Bergstrom
1992) . Used method comparison data to correct a low bias in early
TKNW and TKNF data from OEP/CRL, and thus PON data.
DAITS #10: Summarizes method comparison data available to document
comparability of old and new PON methods.
DAITS #20: Adjustment for ODU TN Kjeldahl data. Used dummy
variables from TN regression to adjust ODU TN data; no adjustment
done to PON data.
DAITS #23: Effects of filter rinsing on POC/PON results. Results
pending, data being collected by VIMS. Contact Betty Salley for
more information.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories was low,
based on CSSP data (AMQAW 1992) . Results were significantly higher
from CBL than at VIMS or ODU. This was apparently due to filter
rinsing at VIMS, which caused loss of PON, and positive pressure
filtration at ODU. In 1992, VIMS stopped rinsing, and
3/93 Guide to Using CBP Water Quality Monitoring Data Page 73
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PARTICOLATE ORGANIC NITROGEN and PARTICULATE NITROGEN continued:
ODU switched to vacuum filtration in 1992, which should increase
agreement. Also, VIMS and ODU use a different elemental analyzer
from CBL.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Bergstrom, P. 1992. Adjusting helix Kjeldahl nitrogen results:
Maryland Chesapeake Bay Mainstem Water Quality Monitoring Program,
1984-1985. CBP/TRS 44/92, Chesapeake Bay Program, Annapolis, MD.
D'Elia, C. et al. 1987. Nitrogen and phosphorus determinations in
estuarine waters: a comparison of methods used in Chesapeake Bay
Monitoring. CBP/TRS 7/87, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 74
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TITLE: TOTAL KJELDAHL NITROGEN, WHOLE AND FILTERED
PARAMETER NAME: TKNW and TKNF
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Kjeldahl nitrogen includes all organic nitrogen, plus part of the
inorganic nitrogen (ammonium or NH4). Nitrate + Nitrite (NO23) is
not included. The whole or filtered sample is digested, usually in
acid, which converts organic nitrogen to ammonium. The sample is
analyzed on the autoanalyzer as ammonium. See Table 4, "Measured
and Calculated Laboratory Parameters" for dates that TKNW & TKNF
were used at each laboratory. The main method differences are in the
heating method during digestion (see next section).
METHOD CHANGES:
There were two minor method changes, although there were three
different digestion methods. See Table 4, "Measured and Calculated
Laboratory Parameters" and Bergstrom 1992 for details.
Two step trends have been identified associated with method changes
when the Kjeldahl methods were stopped (see DAITS issues); TKNW and
TKNF data in the CBP data base have been adjusted to correct for
only one of the step trends, in Maryland data (see Bergstrom 1992
and DAITS #20) .
DAITS ISSUES:
DAITS #2: Adjusting helix Kjeldahl nitrogen data (see Bergstrom
1992). Used method comparison data to correct a low bias in early
TKNW and TKNF data using the helix method from OEP/CRL.
DAITS #10: Summarizes method comparison data available to document
comparability of old and new TKNW and TKNF methods.
DAITS #20: Adjustment for ODU TN Kjeldahl data. Used dummy
variables from TN regression to adjust ODU TN data; no adjustment
was done to TKNW data, since regressions were done on TN data only.
OTHER ISSUES:
TKNF was not analyzed in bottom samples by VIMS or ODU. This
included samples with LAYER = 'B' (bottom) and also LAYER = 'BP'
(below pycnocline). This also affected parameters calculated from
TKNF: TON, PON, and Dissolved Organic Nitrogen (DON) . MDE
laboratories analyzed TKNF in all samples, and TKNW was analyzed in
all samples at all laboratories.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 75
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TOTAL KJELDAHL NITROGEN, WHOLE AND FILTERED continued:
Inter-organization agreement among mainstem laboratories could not
be assessed with CSSP data because Kjeldahl methods were stopped
right after the program started. Earlier two-way split sample data
between VIMS and ODU showed significant inter-organization
differences for TKNW (Bergstrom 1989). These differences could be
a cause of the ODU step trend in TN (see DAITS #20) , since ODU TKNW
results were usually higher than VIMS results. TKNF was not
analyzed because the samples used were bottom samples.
OTHER DOCUMENTATION:
Bergstrom, P. 1989. Split sample water quality results from
laboratories participating in the Chesapeake Bay Program: 1985-1989.
CBP/CSSP Report Series #1, Chesapeake Bay Program, Annapolis, MD.
Bergstrom, P. 1992. Adjusting helix Kjeldahl nitrogen results:
Maryland Chesapeake Bay Mainstem Water Quality Monitoring Program,
1984-1985. CBP/TRS 44/92, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 76
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TITLE: NITRITE + NITRATE, FILTERED AND NITRATE, FILTERED
PARAMETER NAME: NO23 and NO3
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Cadmium reduces NO3 to NO2; then the sum of N03 and N02 are
determined as NO2 by the diazo method with an autoanalyzer (EPA
method 353.2). Calculate NO3 = NO23 - NO2.
METHOD CHANGES:
No major method changes. ODU originally reported NO23 as "N03" but
this was later corrected in the CBP data base. NO3 has never been
measured directly.
BAITS ISSUES:
None
OTHER ISSUES:
Unfiltered N023 results have been reported in some tributary
monitoring programs, and may have been used in historical mainstem
data. In the Potomac component of the CSSP, unfiltered NO23 results
were slightly higher than filtered results (see AMQAW 1992).
Filtered samples were used starting in October, 1990, which
eliminated the difference (AMQAW 1992) .
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992).
NO3 is highly soluble in water, and can be present in runoff and
ground water in high concentrations (10-15 mg/1 in some
tributaries) . NO3 concentrations may be related to river" flow,
especially in or near major rivers.
Phytoplankton prefer to use NH4 as a nitrogen source, since it
contains more energy, but will use NO23 when NH4 is in short supply.
See CBP 1992 for details. Some wastewater treatment plants convert
NH4 to NO23 (nitrification) to make it less attractive to
phytoplankton, raising the NO23 concentration downstream.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 77
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NITRITE + NITRATE, FILTERED AND NITRATE, FILTERED continued:
Chesapeake Bay Program (CBP). 1992. Trends in Nitrogen in the
Chesapeake Bay (1984-1990) . CBP/TRS 68/92, Chesapeake Bay Program,
Annapolis, MD.
Guide to Using CBP Water Quality Monitoring Data Page 78
-------
TITLE: NITRITE, FILTERED
PARAMETER NAME: NO2
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Determined directly by the automated sulfanilamide method with an
autoanalyzer (EPA method 354.1), except ODU determines the
concentration manually with a spectrophotometer.
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
NO2 may be below the MDL, complicating analyses of this parameter.
N02 concentrations are usually less than NO3 or NH4 concentrations.
It is produced as an intermediate product in nitrification: NH4 is
oxidized to N02, then N02 is oxidized to N03.
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992) .
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 79
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TITLE: AMMONIUM, FILTERED
PARAMETER NAME: NH4
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Determined directly with an autoanalyzer, using the automated
alkaline phenol hypochlorite method (EPA 350.1 or equivalent).
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
NH4 is released (mineralized) by anoxic bottom sediments, usually in
the summer. Thus, annual peaks usually occur in summer bottom
samples.
Phytoplankton prefer to use NH4 as a nitrogen source, since it
contains more energy, but will use N023 when NH4 is in short supply.
See CBP 1992 for details. Some wastewater treatment plants convert
NH4 to NO23 to make it less attractive to phytoplankton
(nitrification), lowering the NH4 concentration downstream.
Inter-organization agreement among mainstem laboratories is high,
based on CSSP data (AMQAW 1992).
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Chesapeake Bay Program (CBP). 1992. Trends in Nitrogen in the
Chesapeake Bay (1984-1990). CBP/TRS 68/92, Chesapeake Bay Program,
Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 80
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TITLE: DISSOLVED INORGANIC NITROGEN
PARAMETER NAME: DIN
UNITS OF MEASURE: mg/1 &B N
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Always calculated, from DIN = N023 + NH4.
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
A habitat requirement for Submerged Aquatic Vegetation (SAV) growth
has been established for DIN. April-October median surface values
should be less than 0.15 mg/1 in higher salinity regions (>5 ppt).
See Batiuk et al. (1992) for details.
OTHER DOCUMENTATION:
Batiuk et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation
Habitat Requirements and Restoration Goals: A Technical Synthesis.
CBP/TRS 52/92.
Chesapeake Bay Program (CBP) . 1992. Trends in Nitrogen in the
Chesapeake Bay (1984-1990). CBP/TRS 68/92, Chesapeake Bay Program,
Annapoli s, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 81
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TITLE: DISSOLVED ORGANIC NITROGEN and TOTAL ORGANIC NITROGEN
PARAMETER NAME: DON and TON
UNITS OF MEASURE: mg/1 as N
METHOD CODES: See CHESSES list
GENERAL METHOD:
Calculated as follows:
DON = TKNF - NH4 or TON - NH4 - NO23;
TON = TKNW - NH4 or TN - NH4 - N023.
See Table 4, "Measured and Calculated Laboratory Parameters" for details.
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
DON can be negative, if NH4 exceeds TKNF or (NH4 + N023) exceeds
TON. TON can be negative, if NH4 exceeds TKNW or (NH4 + N023)
exceeds TN. If either is negative, it should be set to 0.
OTHER DOCUMENTATION:
None
3/93 Guide to Using CBP Water Quality Monitoring Data Page 82
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TITLE: TOTAL ORGANIC CARBON
PARAMETER NAME: TOC
UNITS OF MEASURE: mg/1 as C
METHOD CODES: See CHESSKE list
GENERAL METHOD:
Direct: The three mainstem laboratories used the same method,
persulfate oxidation at 100 C, with two different instruments. CBL
used an Oceanographic Instruments (OI) ampule instrument, and later
an 01 injection instrument; ODU uses an OI ampule instrument. VIMS
never did TOC analyses; ODU analyzed samples from all VIMS stations..
Calculated: From TOC = DOC + POC.
METHOD CHANGES:
In Maryland, CRL used manual injection methods which were
unreliable, and the data should be used with caution before 5/15/85
(see DAITS #18) . CBL changed from OI ampule to OI injection on
3/1/87. See Table 4 for details.
In Virginia, ODU did DOC (and TOC direct until 12/87) for all ODU
and VIMS stations until 7/90, when VIMS started DOC analyses for
VIMS stations.
DAITS ISSUES:
DAITS #10: Summarizes method comparison data available to document
comparability of old and new TOC methods.
DAITS #18: Manual injection carbon data. CRL used a manual
injection method where the results depended on how forcefully the
sample was injected. Analytical Methods and Quality Assurance
Workgroup (AMQAW) members recommended against using any TOC or DOC
results for Maryland mainstem stations before 5/15/85.
DAITS #21: Dissolved organic carbon method comparisons. Salley et
al. (1992) summarizes comparisons at VIMS stations; other
comparisons at a wider range of salinities are ongoing.
DAITS #23: Effects of filter rinsing on POC/PON results. Results
pending, data being collected by VIMS. Contact Betty Salley for
more information.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 83
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TOTAL ORGANIC CARBON continued:
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories for TOC
calculated was high, based on CSSP data {AMQAW 1992) . Even though
both DOC and POC had low agreement, when added together the
differences apparently disappeared.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992 .
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
3/93- Guide to Using CBP Water Quality Monitoring Data Page 84
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TITLE: DISSOLVED ORGANIC CARBON
PARAMETER NAME: DOC
UNITS OF MEASURE: mg/1 as C
METHOD CODES: See CHESSEE list
GENERAL METHOD:
The three mainstem laboratories currently use two different methods,
using three different instruments. CBL and ODU use persulfate
oxidation at 100 C, and do not preserve the samples in the field.
CBL does the analysis with an Oceanographic Instruments (01)
injection instrument, and ODU uses an OI ampule instrument. VIMS
uses a Shimadzu high-temperature catalyst method, and preserves the
sample in the field with hydrochloric acid.
METHOD CHANGES:
In Maryland, CRL used manual injection methods which were
unreliable, and the data should not be used (See DAITS #18). CBL
changed from 01 ampule to OI injection on 3/1/87.
In Virginia, ODU analyzed DOC (and TOC until 12/87) for all ODU and
VIMS stations until 7/90, when VIMS started DOC analyses for VIMS
stations. The lab at ODU that analyzed DOC changed for VIMS
stations in 1/88, and for ODU stations in 9/88, from Dr.
Wolfinbarger's lab to Steve Sokolowski's lab (AMRL). There was no
method change, but percent recoveries became much less variable.
Before the lab change, DOC recoveries ranged from 50-186%, and their
standard deviation was 24%. After the change, DOC recoveries ranged
from 79-122%, and their standard deviation was only 8%.
DAITS ISSUES:
DAITS #18: Manual injection carbon data. CRL used a manual
injection method where the results depended on how forcefully the
sample was injected. Analytical Methods and Quality Assurance
Workgroup (AMQAW) members recommended against using any TOC or DOC
results for Maryland mainstem stations before 5/15/85.
DAITS #21: Dissolved organic carbon method comparisons. Salley et
al. (1992) summarizes comparisons at VIMS stations; other
comparisons at a wider range of salinities are ongoing.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories was low,
based on CSSP data (AMQAW 1992). Results were significantly higher
from VIMS; the Shimadzu method apparently recovers more DOC than
other methods.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 85
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DISSOLVED ORGANIC CARBON continued:
OTHER DOCUMENTATION:
AMQAW. 1992. Chesapeake Bay Coordinated Split Sample Program Annual
Report, 1990-1991. CBP/TRS 76/92, Chesapeake Bay Program,
Annapolis, MD.
Salley, B., et al. 1992. A comparison of two methods of measuring
dissolved organic carbon. Special Scientific Report #128, Virginia
Institute of Marine Science (VIMS), Gloucester Point, VA.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 86
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TITLE: PARTICULATE ORGANIC CARBON and PARTICULATE CARBON
PARAMETER NAME: POC
UNITS OF MEASURE: mg/1 as C
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Calculated: from POC = TOC - DOC.
Direct: All mainstem laboratories determine from a filter combusted
at 975-1050 C using an elemental analyzer. The results may include
some inorganic carbon, but the parameter is still called POC in the
CBP data base, not PC, to agree with the name for the calculated
method.
METHOD CHANGES:
Major method changes have occurred. See Table 4, "Measured and
Calculated Laboratory Parameters" for dates that each method was
used at each laboratory. The change to POC direct was made to avoid
having to calculate any parameters by subtraction, since
calculations by subtraction were shown to be less accurate and often
yield negative values (see D'Elia et al. 1987, although it does not
discuss carbon methods).
DAITS ISSUES:
DAITS #10: Summarizes method comparison data available to document
comparability of old and new POC methods.
DAITS #23: Effects of filter rinsing on POC/PON results. Results
pending, data being collected by VIMS. Contact Betty Salley for
more information.
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories was low,
based on CSSP data (AMQAW 1992). Results were significantly higher
from CBL than at VIMS or ODU. Th,is was apparently' due to filter
rinsing at VIMS, which caused loss of POC, and positive pressure
filtration at ODU. In 1992, VIMS stopped rinsing, and ODU switched
to vacuum filtration, which should increase agreement. VIMs and ODU
also use a different elemental analyzer from the one used by CBL.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW) . 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 87
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PARTICOLATE ORGANIC CARBON and PARTICDLATB CARBON continued:
D'Elia, C. et al. 1987. Nitrogen and phosphorus determinations in
estuarine waters: a comparison of methods used in Chesapeake Bay
Monitoring. CBP/TRS 7/87, Chesapeake Bay Program, Annapolis, MD.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 88
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TITLE: SILICA, FILTERED
PARAMETER NAME: SI
UNITS OF MEASURE: mg/1 as SI
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Determined with autoanalyzer using reduction of silicomolybdate to
molybdenum blue with ascorbic acid.
METHOD CHANGES:
No major method changes.
DAITS ISSUES:
None
OTHER ISSUES:
Silica is reported as SIO2 (silicate, the soluble form) by the
Virginia tributary laboratory (DCLS); this should be converted to
mg/1 as SI by dividing by 2.14. SI may also have been reported this
way in some mainstem historical monitoring data.
Inter-organization agreement was fairly low at mainstem
laboratories, based on CSSP data (AMQAW 1992) . CBL had
significantly lower results than VIMS or ODU; the differences were
larger than the analytical precision in 5 of 9 cruises analyzed.
Possible causes of these differences are under investigation.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.-
t
3/93 Guide to Using CBP Water Quality Monitoring Data Page 89
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TITLE: TOTAL SUSPENDED SOLIDS
PARAMETER NAME: TSS
UNITS OF MEASURE: mg/1
METHOD CODES: See CHESSEE list
GENERAL METHOD:
A known volume of sample is filtered through a pre-weighed filter.
The filter is dried at 103-105 C, re-weighed, and the dry weight of
TSS is calculated by subtraction (EPA method 160.2). This is
converted to mg/1 TSS by multiplying by the volume of water
filtered.
METHOD CHANGES:
No major method changes. All mainstem laboratories use the same
method.
DAITS ISSUES:
DAITS #1: Data censoring criteria. High TSS values in bottom
samples are sometimes used as an indicator that the sample pump had
hit the bottom, which stirred up bottom sediments. MDE mainstem
data sometimes include the Analysis Problem Code "TS" or "SS" to
indicate TSS data deleted for this reason; particulate nutrient
parameters (PHOSP, POC, PON) may also be deleted.
OTHER ISSUES:
Inter-organization agreement was fairly low at mainstem
laboratories, based on CSSP data (AMQAW 1992) . CBL had
significantly lower results than VIMS or ODU; the differences were
larger than the analytical precision in 4 of 7 cruises analyzed.
Possible causes of these differences are under investigation.
A habitat requirement for Submerged Aquatic Vegetation (SAV) growth
has been established for TSS. April-October median surface values
should be less than 15 mg/1 baywide. See Batiuk et al. (1992) for
details.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup (AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Batiuk et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation
Habitat Requirements and Restoration Goals: A Technical Synthesis.
CBP/TRS 52/92.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 90
t
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TITLE: CHLOROPHYLL A AND PHAEOPHYTIN, SPECTROPHOTOMETRIC
PARAMETER NAME: CHLA and PHBA
UNITS OF MEASURE: ug/1
METHOD CODES: See CHESSES list
GENERAL METHOD:
Both are determined spectrophotometrically, using acetone extraction
from a ground filter, and calculated from Optical Density (OD)
readings at several wavelengths. See Table 4, "Measured and
Calculated Laboratory Parameters" for details.
Chlorophyll in the Chesapeake Bay is also determined via fluorometry
(see next page) and remote sensing, but remote sensing results are
not currently included in the CBP data base.
METHOD CHANGES:
Optical density wavelengths and calculation methods changed; see
Table 4, "Measured and Calculated Laboratory Parameters" for
details.
DAITS ISSUES:
None
OTHER ISSUES:
Inter-organization agreement among mainstem laboratories was high
for both CHLA and PHEA, based on CSSP data (AMQAW 1992) .
A habitat requirement for Submerged Aquatic Vegetation (SAV) growth
has been established for CHLA. April-October median surface values
should be less than 15 ug/1 baywide. See Batiuk et al. (1992) for
details.
OTHER DOCUMENTATION:
Analytical Methods and Quality Assurance Workgroup '(AMQAW). 1992.
Chesapeake Bay Coordinated Split Sample Program Annual Report, 1990-
1991. CBP/TRS 76/92, Chesapeake Bay Program, Annapolis, MD.
Batiuk et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation
Habitat Requirements and Restoration Goals: A Technical Synthesis.
CBP/TRS 52/92.
D'Elia et al. 1986. Methodological comparisons for nitrogen and
chlorophyll determinations in estuarine water samples. University
of Maryland, Center for Estuarine and Environmental Studies,
Publication UMCEES-CBL-86-55.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 91
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TITLE: CHLOROPHYLL A AND PHAEOPHYTIN, FLOOROMETRIC
PARAMETER NAME: CHLAF and PHEAF
UNITS OF MEASURE: ug/1
METHOD CODES: See CHESSEE list
GENERAL METHOD:
Both are determined with a fluorometer, either in the field (CHLAF
only) or from a filter in the laboratory (CHLAF and PHEAF) .
Currently, only CHLAF is reported in CBP data, measured directly in
the field from water passing through the instrument, without
filtration. This is performed both during the vertical profile at
each station, and in near-surface samples collected with a hull pump
while the boat is underway (horizontal profiles). The fluorometer
is calibrated against spectrophotometric chlorophyll results.
METHOD CHANGES:
None
DAITS ISSUES:
DAITS #27, "Fluorometric chlorophyll data structure." The best way
to store the vertical and horizontal profiles of CHLAF in the CBP
data base is being developed.
OTHER ISSUES:
A habitat requirement for Submerged Aquatic Vegetation (SAV) growth
has been established for CHLA, and could also be used for CHLAF.
April-October median surface values should be less than 15 ug/1
baywide. See Batiuk et al. (1992) for details.
CHLAF and PHEAF are not reported in CSSP data, so no data are
available to assess inter-organization agreement.
OTHER DOCUMENTATION:
Batiuk et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation
Habitat Requirements and Restoration Goals: A Technical Synthesis.
CBP/TRS 52/92.
D'Elia et al. 1986. Methodological comparisons for nitrogen and
chlorophyll determinations in estuarine water samples. University
of Maryland, Center for Estuarine and Environmental Studies,
Publication UMCEES-CBL-86-55.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 92
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D. Other Parameters
Several other parameters record the weather and sea state during
sampling. These are:
Air Temperature (ATEMP)
Cloud Cover (CLOUD)
Tidal stage (TIDE)
Wave Height (WAVHGT)
Wind Direction (WINDIR)
Wind Speed (WINDSPD)
Except for ATEMP, which is degrees Celsius, these are all character
variables. Their allowable values are defined in the applicable sections
of CBP (I992a), "Chesapeake Bay Program Data Management Plan." Their use
may vary among different sampling organizations and at different times.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 93
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E. Measured and Calculated Laboratory Parameters
Table 4 shows which laboratory parameters were measured, and which were
calculated, for each mainstem laboratory and time period. Field parameters are
not included. Some major method differences are noted (including digestion
methods for some parameters) but space prevented any detailed listing of methods.
See Chapter III, section C, Water Quality Parameters, for more information about
specific parameters. See Table 3, "Parameter Titles and Variable Names by Data
Category," for definitions of variable names.
This table is designed to present an overview of how the measured parameters
changed during the monitoring program, and when overlap data are available for
method comparisons. Unlike some monitoring programs, the CBP does not currently
require specific analytical methods, and method changes are allowed as long as
they will improve data quality, and they are documented with method comparison
data.
The major method change that was made in CBP mainstem monitoring involved a
change from EPA standard methods to oceanographic methods for nutrients and
carbon. In EPA standard methods, total (whole water) and dissolved (filtered
sample) nutrients (nitrogen and phosphorus) and carbon are measured directly, and
particulate nutrients and carbon are calculated by subtraction, total - dissolved
fractions. In oceanographic methods, dissolved and particulate nutrients and
carbon are measured directly, and total nutrients and carbon are calculated from
dissolved + particulate fractions. In estuarine samples,, the EPA methods could
produce negative values for the calculated particulate fractions, and the
nitrogen method (Kjeldahl) does not perform well. D'Elia et al. (1987) discussed
these problems and showed that higher data quality could be achieved with the
oceanographic methods. Oceanographic methods have been used since October 1987
for all mainstem CBP data; data from Maryland stations also used these methods
during 1985-1986 (see Table 4 for details).
3/93 Guide to Using CBP Water Quality Monitoring Data Page 94
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Table 4. Measured and Calculated Laboratory Parameters.
Maryland Office of Environmental Programs (MD/OEP)/ Maryland Department of the
Environment (MD/MDE)
PARAMETERS MEASURED
DIRECTLY
OEP staff at CRL*
Cruises 1-18
6/17/84-5/15/85
CBL*
Cruises 19-47
5/16/85-9/86
Carbon species:
Nitrogen species:
Phosphorus species:
Other:
TOC, DOC
NO23, NO2, NH4,
TKNW**, TKNF**
TP***, TOP***, P04P
TSS, SI
Pigment/OD species: CHLA, PHEA
(calc. at CRL)
PC(=POC), DOC
NO23, NO2, NH4
TON, PON
TDP, PO4F, PHOSP
TSS, SI
OD630B,645B, 663A,B,
665A, 750A,B (June)****
(analyzed by MDHMH)
COMPUTED VARIABLES
Monochromatic active chlorophyll_a :
Monochromatic phaeophytin :
where (K=extract vol/sample volume*light path)
26.73*[(OD663B-OD750B)
-(OD665A-OD750A)])*K
26.73* £l.7(OD665A-OD750A)
-(OD663B-OD750B)]*K
Carbon spp :
Nitrogen spp:
Phos . spp :
POC:
TOC:
NO3:
TON:
PON:
DON:
TON:
DIN:
TN:
DOP:
PHOSP
TP:
TOC - DOC
(direct)
N023 - NO2
TKNF** + N023
TKNW** - TKNF**
TKNF** - NH4
TKNW** - NH4
NO23 + NH4
TKNW** + NO23
TDP - PO4F
:TP - TDP
(direct)
(direct)
POC + DOC
NO23 - N02
(direct)
(direct)
TDN - NH4 -
TN - NH4 -
NO23 + NH4
PON + TDN
TDP - PO4F
(direct)
TDP + PHOSP
NO23
N023
* Analyses by OEP staff at EPA Central Regional Laboratory, Annapolis.
Later analyses done at Chesapeake Biological Laboratory, Solomons, by CBL
staff, except CHLA & PHEA were analyzed at MD Dept. Health & Mental
Hygiene (MDHMH) Laboratory, Baltimore.
** Using helix digestion; data were later adjusted to correct low bias.
*** Acid persulfate digestion; other TP & TDP used alkaline persulfate.
**** F0r Cruise 33 (2/86) OEP submitted the same OD data as on the next page.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 95
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Table 4 (continued). Measured and Calculated Laboratory Parameters.
Maryland Department of the Environment (MDE), continued
- ALL CBL
PARAMETERS MEASURED Cruises 40-47 Cruises 48-67 Cruises 68-
DIRECTLY 6/86-9/86* 10/86-9/87 10/87-
Carbon species:
Nitrogen species:
Phosphorus species:
Other:
Pigment/CD species:
COMPUTED VARIABLES-
PC(=POC), DOC
NO23, N02, NH4
TON, PON,
TKNW**, TKNF**
TOC, DOC
NO23, NO2, NH4
TKNW**, TKNF**
PC(=POC),DOC
NO23,N02,NH4
TON, PON
TOP,TOP***,TP, TDP***,TP***,PO4F TOP,PO4F,PHOSP
TP***,PO4F, PHOSP
TSS, SI
TSS, SI
TSS, SI
OD630B,645B,647B, OD630B,645B,647B, OD630B,645B,
663B, 664B, 665A, 663B, 664B, 665A, 647B, 663B,
750A,B 750A,B 664B,665A,750A,B
Monochromat i c
active chlorophyll_a : 26.7*[(OD664B-OD750B) - (OD665A-OD750A) ] * K
Monochromatic phaeophytin : 26.7*[1.7(OD665A-OD750A) - (OD664B-OD750B)]*K
where (K=extract vol/sample volume*light path)
Carbon spp:
Nitrogen spp:
POC: (direct)
TOC: POC + DOC
N03: NO23 - NO2
TON: (direct)
and TKNF** + NO23
PON: TKNW** - TKNF**
and (direct)
DON: TKNF** - NH4
and TON - NH4 - NO23
TON: TKNW** - NH4
and TN - NH4 - NO23
DIN: NO23 + NH4
TN: PON + TON
and TKNW** + NO23
TOC - DOC
(direct)
NO23 - NO2
TKNF** + NO23
TKNW** - TKNF**
TKNF** - NH4
TKNW** - NH4
NO23 + NH4
TKNW** + NO23
Phos. spp:
OOP: TOP - PO4F TDP - PO4F
PHOSP:TP - TDP & direct TP - TDP
TP: TOP+PHOSP & direct (direct)
(direct)
POC + DOC
NO23 - NO2
(direct)
(direct)
TDN-NH4-NO23
TN-NH4-NO23
NO23 + NH4
PON + TON
TDP - PO4F
(direct)
TOP + PHOSP
* Overlap period included both sets of methods to permit method comparisons.
** Using block digestion.
*** Acid persulfate digestion; other TP & TDP by CBL used alkaline persulfate.
3/93
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Table 4 (continued). Measured and Calculated Laboratory Parameters.
Virginia Water Control Board (VWCB) / Virginia Institute of Marine Science (VIMS)
PARAMETERS MEASURED
DIRECTLY
Cruises 1-67
6/84 - 9/87
Cruises 68 -
10/87 -
Carbon species:
Nitrogen species:
TOC*, DOC*
NO23, NO2, NH4,
TKNW**, TKNF**
Phosphorus species: TP, TDP, PO4F
Other:
Pigment/OD species:
TSS, SI
OD630B, 647B, 664B, 665A,
750A,B
DOC*, POC,
(TOC* TO 12/87)
NO23, NO2, NH4,
(TKNW**,TKNF**TO 12/87),
TON, PON
TDP***,PO4F,PHOSP
(TP TO 12/87)
TSS, SI
OD630B,647B,664B,665A,
750A,B
COMPUTED VARIABLES --
Active chlorophyll_a:
26.7* [ (OD664B-OD750B)-(OD665A-OD750A)]*K
Monochromatic phaeophytin: 26.7*[1.7(OD665A-OD750A)-(OD664B-OD750B)]*K
where K=extract vol/sample volume*light path.
Carbon spp. POC:
TOC* - DOC*
(direct)
Nitrogen
Phos . spp
N03:
TON:
PON:
DON:
TON:
DIN:
TN:
OOP:
DIP:
PHOSP :
TP:
NO23 - N02
TKNF** + N023
TKNW** - TKNF**
TKNF** - NH4
TKNW** - NH4
NO23 + NH4
TKNW** + NO23
TDP - PO4F
P04F
TP - TDP
(direct)
NO23 - N02
(direct)****
(direct)****
TON - NO23 - NH4****
TN - N023 - NH4****
N023 + NH4
PON + TDU****
TDP - PO4F
PO4F
(direct, 11/87)****
TDP + PHOSP****
* TOC & DOC analyzed by ODU, until VIMS started analyzing DOC in 7/90.
** Using macro manual digestion; acid persulfate, then alkaline persulfate
in 7/87. TKNF not measured in bottom or below pycnocline samples.
*** Changed from acid persulfate to alkaline persulfate digestion in 7/88.
**** Where methods changed, both formulas can be used from 10/87 to 12/87.
Guide to Using CBP Water Quality Monitoring Data Page 97
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Table 4 (continued). Measured and Calculated Laboratory Parameters.
Virginia Water Control Board (VWCB) / Old Dominion University (ODU)
PARAMETERS MEASURED
DIRECTLY
Cruises 1-11.
6/84 - 12/84
Cruises 12-67
1/85 - 9/87
Carbon species:
Nitrogen species:
Phosphorus species:
Other:
Pigment/OD species:
COMPUTED VARIABLES
TOC, DOC
NO23, NH4,
TKNW*, TKNF*
TP**, TOP**, PO4F
TSS, SI
OD630B,645B,663B,
665A, 750A,B
TOC, DOC
NO23, NH4,
TKNW*, TKNF*
TP**, TOP**, PO4F
TSS, SI
OD630B,647B,664B
665A,750A,B***
Monochromatic active
chlorophyll_a: 26.73*[(OD663B-OD750B)
-(OD665A-OD750A) ] )*K
Monochromat i c
phaeophytin:
26.73* [1.7(OD665A-OD750A)
-(OD663B-OD750B)]*K
where (K=extract vol/sample volume*light path)
Carbon spp. POC: TOC - DOC
26.7*[(OD664B-OD750B)
-(OD665A-OD750A) ] *K
26.7* [1.7(OD665A-OD750A)
-(OD664B-OD750B)]*K
TOC-DOC
Nitrogen :
Phos . spp :
NO3:
TON:
PON:
DON:
TON:
DIN:
TN:
DOP:
DIP:
PHOSP :
NO23 - NO2
TKNF* + NO23
TKNW* - TKNF*
TKNF* - NH4
TKNW* - NH4
NO23 + NH4
TKNW* + NO23
TDP - PO4F
PO4F
TP - TDP
N023 - N02
TKNF* + NO23
TKNW* - TKNF*
TKNF* - NH4
TKNW* - NH4
NO23 + NH4
TKNW* + N023
TDP - PO4F
P04F
TP - TDP
* No data for June 1984; using block digestion after that. TKNF was not
measured in bottom or below pycnocline samples.
** Using acid persulfate digestion.
*** OD480B and OD510B were added to the data submission in 11/85, but are not
used in calculations.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 98
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Table 4 (continued). Measured and Calculated Laboratory Parameters.
Virginia Water Control Board / ODU, continued
PARAMETERS MEASURED
DIRECTLY
Cruises 68 -
10/87 -
Carbon species:
Nitrogen species:
Phosphorus species:
Other:
Pigment/OD species:
COMPUTED VARIABLES-
Monochromatic active
chlorophyll_a:
Monochromat i c
phaeophytin:
PC(=POC), DOC (TOC to 12/87)
NO23, NH4, TON, PON
(TKNW*, TKNF* to 12/87)
TDP**, PO4F, PHOSP (TP** to 12/87)
TSS, SI
OD480B,510B,630B,647B,
664B,665A,750A,B
26.7*[(OD664B-OD750B)
-(OD665A-OD750A)]*K
26.7*[1.7(OD665A-OD750A)
-(OD664B-OD750B)]*K
where (K=extract vol/sample volume*light path)
Carbon spp. POC:
Nitrogen : NO3:
TON:
PON:
DON:
TON:
DIN:
TN:
Phos. spp DOP:
DIP:
PHOSP:
(direct) (and TOC - DOC through 12/87)
NO23 - N02
(direct) (and TKNF* + N023 through 12/87)
(direct) (and TKNW* - TKNF through 12/87)
TON - N023 - NH4 (and TKNF* - NH4 through 12/87)
TN - NO23 - NH4 (and TKNW* - NH4 through 12/87)
NO23 + NH4
TON + PON (and TKNW* + *NO23 through 12/87)
TDP - PO4F
PO4F
(direct) (and TP - TDP through 12/87)
* Using block digestion. TKNF was not measured in bottom or below
pycnocline samples.
** Using acid persulfate digestion.
Guide to Using CBP Water Quality Monitoring Data Page 99
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F. Lower Detection Limits of Water Quality Parameters
Laboratories in the Chesapeake Bay Program submit data that are censored
at a lower detection limit, called the Method Detection Limit or MDL.
These are listed in Table 5; units are in mg/1 as the element except where
noted. Concentrations that are less than this limit are raised to the
MDL, and the associated detection limit flag (variable_D) is set to "<".
For example, if the MDL for ammonium (NH4) was 0.003 mg/1, and the
measured concentration was 0.002 mg/1, the reported value would be 0.003
mg/1, and the variable NH4JD would be set to "<".
The method of calculating the MDL at mainstem laboratories varied over
time, and at different laboratories. The current method at most
laboratories was agreed upon by Analytical Methods and Quality Assurance
Workgroup (AMQAW) members in 1988. Using this method, MDLs represent 3
times the standard deviation of 7 low-level replicates. This method has
been used at CBL since 1987, and at VIMS starting 5/1/88. MDLs at CBL
prior to 1987 were based on 3 times the standard deviation of laboratory
duplicates for each analyte. MDLs at VIMS before 5/88 were based on the
lowest standard used. VIMS limits varied before 5/88 because their MDL
was the predicted value for the lowest standard, based on the regression
for that cruise. ODU calculates 3 times the standard deviation of 7 low-
level replicates, but only uses this as their MDL if that concentration
has a peak height that is at least 1-2% of full scale for that parameter.
ODU uses the concentration equal to 1-2* of full scale as their MDL if the
calculated MDL is less than that value, similar to an Instrument Detection
Limit. The MDL method used at OEP/CRL (the Maryland lab before 5/15/85}
is unknown, but was probably based on lowest standard used. Some
laboratories determine MDLs annually, while others determine them only
when there is a method change. See the Chesapeake Bay Program Data
Management Plan (CBP 1992a) for definitions of different types of
detection limits.
Field parameter MDLs from MDE and ODU are "calibrated accuracy" from the
manufacturer of the instrument they use (Hydrolab), and MDE & ODU field
data are not censored at these values. VIMS MDLs for field parameters are
determined by the replicate method using the Winkler method for dissolved
oxygen and a salinometer for salinity. MDLs for their CTD and DO meter
measurements are not available. The SECCHI MDL is the minimum depth
marking.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 100
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Calculated parameters in the CBP data base are flagged "<" if any of the
components are below the MDL. See Table 4, "Measured and calculated
parameters" to determine which parameters were measured directly at each
laboratory during each time period. The MDLs for calculated parameters in
this table are the sum of the MDLs of the components, and are followed by
a "+". MDLs for three of the less frequently used calculated parameters
are not listed (DOP, DON, TON), but these can be calculated by the data
user. During overlap periods, when two methods can be used for calculated
parameters, the MDLs shown are for the newer method, which is what CBP
data retrieval software uses for overlap periods. For example, when TN
can be calculated as TKNW+NO23 or TDN+PON, CBP software uses TN = TDN+PON.
Some parameters also have upper detection limits, but since most
parameters can be diluted and re-analyzed when these are encountered,
these rarely result in censored values in the data base. Parameters
analyzed directly from filters (e.g., POC and PON) cannot be diluted, and
SECCHI can have an upper detection limit when the disk is visible on the
bottom.
When using the values in this list for trend analysis, data users should
be aware that there were not necessarily any reported values that were
censored at the values shown. An examination of the data used is
necessary to determine the highest censored concentration during the
period analyzed. For calculated parameters, such as Total Nitrogen, there
is the added complication that only one component may be censored, and it
may make up a small part of the total. For more information see "Trends
in Nitrogen in the Chesapeake Bay (1984-1990)" (CBP 1992b).
If the day of the month is not given, it is the start of the month for
starting dates, or the end of the month for ending dates.
Guide to Using CBP Water Quality Monitoring Data Page 101
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Table 5. Lower Detection LimitB of Water Quality Parameters.
Chesapeake Bay Mainstem Monitoring Program
PARAMETER
MD/OEP-MDE
(CRL then CBL)
TN .240+ (6/84-2/85)
(Calc. .2009+(3/85-5/15/85)
TKNW + .031+ (5/16/85-9/86)
N023,or .2009+(10/86-9/87)
TDN+ .0305+(10/87-)
PON)
TKNW & .20 (6/84-5/15/85)
TKNF .20 (6/86-9/87)
TON .240+ (6/84-2/85)
(Calcu- .2009+(3/85-5/15/85)
lated, .03 (5/16/85-9/86)
then ,02 (10/87-)
direct)
PON .40+
(Calcu- .001
lated, .40+
then .0105
direct)
(6/84-5/15/85)
(5/16/85-9/86)
(10/86-9/87)
(10/87-)
DIN .060+ (6/84-1/85)
(Calcu- .080+ (2/85)
lated .0039+ (3/85-9/87)
NH4+ .00315+(10/87-4/15/88)
NO23) .00515+(4/16/88-7/88)
.00315+(8/88)
.0032+ (9/88-)
VA/VWCB
(ODU)
.11+ (6/84-3/15/86)
.105+ (3/16/86-4/15/86)
.11+ (4/16/86-4/30/86)
.105+ (5/86-9/87)
.10+ (10/87-8/90)
.075+ (9/90-10/90)
.061+ (11/90-)
.10 (6/84-2/88)
.11+ (6/84-3/15/86)
.105+ (3/16/86-4/15/86)
.11+ (4/16/86-4/30/86)
.105+ (5/86-9/87)
.05 (10/87-8/90)
.025 (9/90-)
.20+ (6/84-9/87)
.05 (10/87-10/90)
.036 (11/90-)
.02+ (6/84-5/15/85)
.0156+(5/16/85-3/15/86)
.0106+(3/16/86-4/15/86)
.0156+(4/16/86-4/30/86)
.0106+(5/86-6/88)
.0081+(7/88-)
VA/VWCB
(VIMS).
.11*+ (6/84-
.124*+(10/87
.071+ (5/88-
.069+ (6/89-
.045+ (7/90-
.081+ (7/91-
.045+ (2/92-
9/87)
-4/88)
5/89)
6/90)
6/91)
1/92)
.10M.1-.198)
(6/84-1/88)
.12*+ (6/84-10/15/86)
.11*+ (10/16/86-9/87)
.1M.05- .462)
(10/87-4/88)
.045 (5/88-5/89)
.040 (6/89-6/90)
.026 (7/90-6/91)
.075 (7/91-1/92)
.026 (2/92-)
.20*+ (6/84-9/87)
.024M.023-.026)
(10/87-4/88)
.026 (5/88-5/89)
.029 (6/89-6/90)
.019 (7/90-6/91)
.006 (7/91-1/92)
.019 (2/92-)
.02*+ (6/84-4/88)
.0144+ "(5/88-5/89)
.0081+ (6/89-6/90)
.0064+ (7/90-6/91)
.0044+ (7/91-1/92)
.0048+ (2/92-2/93)
.0023+ (3/93-)
* VIMS had variable detection limits during this period, within range shown.
+ Parameter calculated during this period; MDL shown is the sum of the detection
limits of the components. See "List of measured and calculated parameters" for
calculation method during each time period.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 102
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Table 5 (continued). Lower Detection Limits of Water Quality Parameters.
Chesapeake Bay Mainstem Monitoring Program
PARAMETER MD/OEP-MDE
NH4
N023
N02
N03
TP
(Di-
rect,
then
calc. )
(CRL then CBL)
.020 (6/84-1/85)
.040 (2/85)
.003 (3/85-4/15/88)
.005 (4/16/88-7/88)
.003 (8/88-)
.040 (6/84-2/85)
.0009 (3/85-9/87)
.00015 (10/87-8/88)
.0002 (9/88-)
.01 (6/84-2/85)
.0005 (3/85-9/87)
.00015 (10/87-8/88)
.0002 (9/88-)
.050+ (6/84-2/85)
.0014+ (3/85-9/87)
.0003+ (10/87-8/88)
.0004+ (9/88-)
.012 (6/84-1/85)
.01 (2/85)
.005 (3/85-5/15/85)
.0063+ (5/16/85-9/86)
.012 (10/86-9/87)
.0022+ (10/87-)
VA/VWCB
(ODU)
.01 (6/84-5/15/85)
.0056 (5/16/85-)
.01 (6/84-3/15/86)
.005 (3/16/86-4/15/86)
.01 (4/16/86-4/30/86)
.005 (5/86-6/88)
.0025 (7/88-)
.001 (6/84- )
.011+(6/84-3/15/86)
.006+ (3/16/86-4/15/86)
.011+ (4/16/86 -4/30/86)
.006+(5/86-6/88)
.0035+(7/88-)
.01 (6/84-12/86)
.005 (1/87-9/87)
.012+ (10/87-)
VA/VWCB
(VIMS)
.01*(.002-
.013
.006
.004
.002
.004
.0015
.OlM.OOl-
.0014
.0021
.0024
.0008
.004*(.001
.0008
.0015
.0006
.0005
.0002
.014*+
.0022+
.0036+
.0030+
.0029+
.0010+
.01* ( .009-
.02*+
.007+
.008+
.005+
.0022+
.0032+
.051)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-2/93)
(3/93-)
.025)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-1/92)
(2/92-)
-.007)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
-01)
(6/84-10/87)
(11/87-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-5/92)
(6/92-2/93)
(3/93-)
* VIMS had variable detection limits during this period, within range shown.
+ Parameter calculated during this period; MDL shown is the sum of the
detection limits of the components.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 103
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Table 5 (continued). Lower Detection Limits of Water Quality Parameters.
Chesapeake Bay Mainstem Monitoring Program
PARAMETER MD/OEP-MDE
(CRL then CBL)
TDP
PHOSP
(Calc.,
then
direct)
P04F
.012
.01
.005
.012
.001
.024 +
.02 +
.010+
.0013
.024 +
.0012
.012
.007
.0016
.0006
(6/84-1/85)
(2/85)
(3/85-9/86)
(10/86-9/87)
(10/87-)
(6/84-1/85)
(2/85)
(3/85-5/15/85)
(5/16/85-9/86)
(10/86-9/87)
(10/87-)
(6/84)
(7/84-2/85)
(3/85-9/87)
(10/87-)
VA/VWCB
(ODU)
.01 (6/84-11/86)
.005 (12/86-)
.02+ (6/84-11/86)
.015+ (12/86)
.01+ (1/87-9/87)
.007 (10/87-)
.01 (6/84-11/86)
.005 (12/86-)
VA/VWCB
.01*(
.006
.005
.002
.02*+
.01*(
.001
.003
.0002
.0012
.01*(
.002*
.0005
.003
.0006
.0008
.0006
(VIMS)
.009- .012)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-)
(6/84-10/87)
.009-. 01)
(11/87-4/88)
(5/88-5/89)
(6/89-5/92)
(6/92-2/93)
(3/93-)
.009- .013)
(6/84-7/87)
(.001- .004)
(8/87-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
TOC 1.0 (6/84-5/15/85)
(Di- .501+ (5/16/85-9/86)
rect, 1.0 (10/86-9/87)
then .501+ (10/87-8/88)
calc.) .303+ (9/88-)
1.0 (6/84-9/87)
1.24+ (10/87-8/88)
.74+ (9/88-10/90)
.63+ (11/90-)
1.0 (ODU**, 6/84-9/87)
1.581*+(10/87-4/88)
1.099+(5/88-8/88)
.599+ (9/88-5/89)
.604+ (6/89-6/90)
.457+ (7/90-6/91)
.234+ (7/91-1/92)
.597+ (2/92-2/93
.297+ (3/93-)
* VIMS had variable detection limits during this period, within range shown.
** ODU analyzed TOC and DOC for VIMS stations until 7/90.
+ Parameter calculated during this period; MDL shown is the sum of the
detection limits of the components.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 104
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Table 5 (continued). Lower Detection Limits of Water Quality Parameters.
Chesapeake Bay Mainstem Monitoring Program
PARAMETER
DOC
POC
(Calc.,
then
direct)
SI
(as SI)
TSS
CHLA
(ug/1)
PHEA
(ug/1)
* VIMS
** ODtT
1.0
.50
.24
2.0 +
.001
1.5 +
.001
.063
.1
.012
.01
4.0
1.0
1.98
1.5
1+
0.2 +
1 +
0.2 +
had
analA
MD/OEP-MDE
(CRL then CBL)
(6/84-5/15/85)
(5/16/85-8/88)
(9/88-)
(6/84-5/15/85)
(5/16/85-9/86)
(10/86-9/87)
(10/87-8/88)
(9/88-)
(6/84-2/85)
(3/85-3/87)
(4/87-)
(6/84-5/15/85)
(5/16/85-9/87)
(10/87-8/88)
(9/88-)
(6/84-5/15/85)
(MDHMH,
5/16/85-)
(6/84-5/15/85)
(MDHMH,
5/16/85-)
variable detection
/zed TOf and DOC fo
VA/VWCB
1.0
.50
2.0+
.24
.13
.028
.023
.0281
4.0
2.0
0.2 +
1.1+
0.2 +
0.8+
(ODU)
(6/84-8/88)
(9/88-)
(6/84-9/87)
(10/87-10/90)
(11/90-)
(6/84-5/86)
(6/86-12/90)
(1/91-)
(6/84-8/88)
(9/88-)
(6/84-1/91)
(2/91-)
9
(6/84-1/91)
(2/91-)
limits during this
r VIMS stations tint:
VA/VWCB
1.0
.50
.36
.15
.50
.20
2.0+
.581*
.099
.104
.097
.084
.097
.056*
.009
.007
.013
.006
.013
4.0
5.0
1.4
2.0
1.0+
3.2 +
1.32+
1.95+
0.95+
1.0+
3.2 +
1.91+
3.43 +
1.34 +
(VIMS)
(ODU**, 6/84-8/88)
(ODU**, 9/88-6/90)
(VIMS, 7/90-6/91)
(VIMS, 7/91-1/92)
(VIMS, 2/92-2/93)
(VIMS, 3/93-)
(6/84-9/87)
(.581-. 581)
(10/87-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
(.009-. 1)
(6/84-4/88)
(5/88-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
(6/84-4/88)
(5/88-6/91)
(7/91-1/92)
(2/92-)
(6/84-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
(6/84-5/89)
(6/89-6/90)
(7/90-6/91)
(7/91-1/92)
(2/92-)
period, within range shown.
LI 7/90.
+ Parameter calculated during this period.
Guide to Using CBP Water Quality Monitoring Data Page 105
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Table 5 (continued). Lower
Chesapeake
PARAMETER MD/OEP-MDE
(CRL then CBL)
Detection Limits of Water Quality Parameters.
Bay Mainstem Monitoring Program
CHLAF ?*
(ug/1)
PHEAF ?*
(ug/1)
PH 0.1** (6/84-)
(pH units)
DISOXY 0.2** (6/84-)
SALIN 0.7** (6/84-)
*
SECCHI 0 .1
(m)
(6/84-)
VA/VWCB
(ODU)
-Field parameters-
0.1** (6/84-)
0.2** (6/84-)
0.7** (6/84-)
0.0
0.1 (6/84-)
VA/VWCB
(VIMS)
1.5 (6/89-6/90)
1.23 (7/90-)
0.71 (6/89-6/90)
1.10 (7/90-)
0.0?***(6/84-4/88)
0.1 ***(5/88-5/89)
0.15***(6/89-6/90)
0.20***(7/90-6/91)
0.08***(7/91-)
? . (6/84-4/88)
0.04***(5/88-5/89)
0.05***(6/89-6/90)
0.08***(7/90-6/91)
0.07***(7/91-)
0.1
(6/84-)
* Fluorometric chlorophyll, phaeophytin, and KB (light attenuation) are analyzed
by Benedict Laboratory personnel, but not at all MDE mainstem stations.
** Calibrated accuracy provided by manufacturer (Hydrolab) ; these values are not
used to censor results.
*** These limits only apply to Winkler results for DO (DISOX3), not to DISOXY
measured by YSI meter, and to salinometer results for salinity (SALIN2), not to
SALIN measured by the CTD.
Please send any corrections to Peter Bergstrom, CSC/CBPO, 410 Severn Ave.,
Annapolis, MD 21403, (800) 523-2281.
t
3/93
Guide to Using CBP Water Quality Monitoring Data Page 106
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G. Data Analysis Issues Tracking System (DAITS)
Documentation of any problems with data quality is an important part of a
monitoring program. As the Chesapeake Bay Program Mainstem Monitoring
Program reached its fifth anniversary, EPA initiated a systemat^ c review
of the program design and implementation. In the process of this review,
numerous questions were raised which required investigation. To insure
that all of these issues received appropriate attention and to provide
thorough documentation of this process for future users of this important
database, a tracking system was designed which is known as the Data
Analysis Issues Tracking System (DAITS).
DAITS is a central collection point for the registry of all issues which
are raised by those involved in the management, operation and review of
the Chesapeake Bay Program (CBP) monitoring programs. The DAITS will
encompass issues relating to any programs contributing data to the CBP
data base.
Issues focused on the current water quality monitoring program as well as
historical data sets are included. Quality Assurance (QA) data issues are
included in this system as well. The magnitude of the issue is not a
concern. Issues need not be fully developed before they are introduced
into the system. Issues can be informally introduced to the system with
a brief note although contributors are strongly urged to follow the
elements of the format provided below to assist in accomplishing the
appropriate follow-through.
DAITS provides a way to document analysis issues and achieve consensus on
how to deal with them. Pending issues are usually referred to members of
the appropriate Monitoring Subcommittee (MSC) workgroup for resolution;
more than one workgroup may be involved. Issues concerning field or
laboratory methods or QA data are usually referred to the Analytical
Methods and Quality Assurance Workgroup (AMQAW); issues concerning
statistics or other data analysis methods are usually referred to the Data
Analysis Workgroup (DAWG); and issues concerning data management are
referred to the Data Management and Acquisition Workgroup (DMAW)." Once
resolved, issues that require permanent changes to the CBP data base, such
as data adjustments, are approved by the full Monitoring Subcommittee
(MSC) .
The documentation for each issue is stored in computer files. The storage
location and retrieval method are currently under review and may change.
Please contact CBPCC staff to get copies of any issue. The following
summary (Table 6) of pending and completed issues is provided to give data
users an idea of the scope of the issues included; this list is revised
frequently as new issues are added and pending ones are resolved. Contact
CBPCC staff to get the latest information on the status of DAITS issues.
Guide to Using CBP Water Quality Monitoring Data Page 107
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Table 6. Chesapeake Bay Program Data Analysis Issues Tracking System.
ENTRY TARGET >»PENDING ISSUES«<
# DATE DATE TITLE
STATUS Contact
016 12/10/90 4/93
019 5/15/91 4/93
021 11/21/91 5/93
022 11/21/91 5/93
023 11/21/91 6/93
024 1/13/92 5/93
025 7/7/92 6/93
026 8/5/92 5/93
027 10/6/92 5/93
Blank correction for MDHMH TP/TDP Revise BM/MDE
data
Field and laboratory methods matrix Revise CW/EPA
DOC method comparison study Revise BS/VIMS
Field data validation/adjustment Write BN/VIMS
PC/PN filter and rinsing study Pending GB/VIMS
data KW/CBL
Method detection limit (MDL) methods Response PB/CSC
Water quality/nutrient depth sampling Response JL/CSC
protocol for mid-water samples
Revision of analytical problem codes Response CW/EPA
Fluorometric Chlorophyll Data Struct. Write JL/CSC
Status = Write: Writing up issue Response: waiting for responses, Revise:
revising issue with responses, Pending data: waiting for data collection
Contacts: PB/CSC= Peter Bergstrom, BM/MDE = Bruce Michael, CZ/CBL = Carl
Zimmermann, SS/ODU = Steve Sokolowski, CW/EPA = Claudia Walters, BS/VIMS = Betty
Salley, BN/VIMS = Bruce Neilson, GB/VIMS = Grace Battisto, KW/CBL = Kathy Wood,
JL/CSC = John Lecourt.
CSC = Computer Sciences Corp., MDE = Maryland Department of the Environment, CBL
= Chesapeake Biological Laboratory, EPA = Environmental Protection Agency, ODU
= Old Dominion University, VIMS = Virginia Institute of Marine Science.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 108
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Table 6 (continued). Chesapeake Bay Program Data Analysis Issues Tracking
System.
ENTRY
# DATE
>»COMPLETED ISSUES<«
TITLE
001 5/08/90 Criteria for Data Censoring
RESOLUTION: Criteria documented, approved by Analytical
Methods and Quality Assurance Workgroup (AMQAW) on 2/25/92,
writeup done 7/8/92
002 5/14/90 Adjusting Helix Kjeldahl Nitrogen Data
RESOLUTION: Report completed 9/11/91, approved by AMQAW on
11/21/91, by Monitoring Subcommittee (MSC) on 1/22/92, data
adjusted on 8/24/91
003 5/14/90
004 5-14-90
005 5-14-90
006 5-25-90
007 8-28-90
Field and Lab Replicate Methods
RESOLUTION: Documentation completed and reviewed by AMQAW on
7/24/92
Monitoring Data Re-submission
RESOLUTION: Discussed in 9/12/90 Data Management and
Acquisition Workgroup (DMAW) conference call w. Bob Stone,
decided priority too low to pursue
Submitting Control Charts with QA data
RESOLUTION: Same as #4
Setting of Range check limits
RESOLUTION: Part of new Chesapeake Automated Monitoring System
(CAMS) software
Secchi variability
RESOLUTION: Documentation of methods received
3/93
Guide to Using CBP Water Quality Monitoring Data Page 109
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Table 6 (continued). Chesapeake Bay Program Data Analysis Issues Tracking
System.
ENTRY
# DATE
»>COMPLETED ISSUES<«
TITLE
008 8/28/90 Data management procedures
RESOLUTION: Documentation of methods completed, for three
mainstem and three tributary laboratories
009 8-28-90 Using Proc Means in data submission
RESOLUTION: Implemented by CBL, ODU, VIMS
010 9-4-90 Inventory of Method comparison data
RESOLUTION: Completed & approved by AMQAW on 5/14/91
Oil 9/4/90 Lowering method detection limits
RESOLUTION: DCLS and DCRA/CRL lab personnel documented the
steps that will be taken to lower their highest MDLs. Both
labs will use a new autoanalyzer to accomplish this.
012 9-4-90 Criteria for selecting historical data
RESOLUTION: Desirable but not currently funded
013 9-12-90 Data Screening software
RESOLUTION: Part of new CAMS software
014 9-28-90 Reporting of WINDSPD data
RESOLUTION: Reviewed procedures, no changes needed
015 12-10-90 Salinity correction for CBL PO4F data
RESOLUTION: Writeup finished, approved by AMQAW on 5/14/91,
change to CBP data base submitted by MDE on 8/28/92
Guide to Using CBP Water Quality Monitoring Data Page 110
3/93
-------
Table 6 (continued). Chesapeake Bay Program Data Analysis Issues Tracking
System.
ENTRY >»COMPLETED ISSUES<«
# DATE TITLE
017 12-19-90 Percent recovery calculation methods
RESOLUTION: Guidelines for spiking and for percent recovery
calculation were adopted by AMQAW members on 11/13/92.
018 1-29-91 Manual injection carbon data (MD mainstem, 6/84-5/15/85)
RESOLUTION: Writeup finished, approved by AMQAW on 2/19/91,
recommended leaving data in the data base but warning users of
their variability.
020 7/11/91 Adjustment for ODU TN Kjeldahl data
RESOLUTION: AMQAW and Data Analysis Workgroup (DAWG) reviewed
issue, DAWG recommended dummy variable coefficients to lower
Kjeldahl data on 2/4/92, MSC gave final approval to adjust
data base on 4/1/92, data adjusted on 5/8/92
t
3/93
Guide to Using CBP Water Quality Monitoring Data Page 111
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*
i
-------
t
IV. QUALITY ASSURANCE (QA) DATA
A. Introduction
The CBP Mainstem Monitoring data base includes several types of Quality
Assurance (QA) data. They estimate the precision and accuracy of the
water quality data, and include comparisons within the same organization,
and comparisons among results from different organizations. In many
cases, the same data are used by the laboratories involved for Quality
Control (QC) purposes, before the data are sent to CBPO.
Quality assurance data for chemical analyses provides estimates of
precision and accuracy. Precision is the repeatability of measurements by
a single laboratory or monitoring organization, or the agreement of
measurements of the same sample by different monitoring organizations.
The goal of precision measurements is to assess the variability introduced
by the measurement system. This should be known before any variability in
the actual data can be interpreted. Attempting to detect a change in
concentration that is smaller than the inherent variability of the
measurement system will be difficult.
Accuracy is the closeness of analytical measurements to a "true" value for
that method, and is more difficult to assess than precision. In
situations where the "true" value cannot be determined, precision may be
used as a surrogate for accuracy, assuming that measurements which are
very repeatable, especially among different organizations, will tend to be
accurate. A consistent deviation from accuracy is called bias. When bias
is identified, the CBP data involved may be adjusted (if possible) to
increase accuracy, and method changes may be made to reduce the bias.
Adjustments for bias have been made to CBP Total Nitrogen data (see
Chapter III, section C for details).
Precision estimates include differing amounts of the possible variability
in the measurement system. Precision estimates measured by CBP QA data
include three different sources of variability (Table 7, "Summary of CBP
Precision Estimates").
3/93 Guide to Using CBP Water Quality Monitoring Data Page 113
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Table 7. Summary of CBP Precision Estimates.
- SOURCES OF VARIABILITY -
DATA Different Sample Laboratory
SOURCE laboratories acquisition analysis
WITHIN-ORGANIZATION PRECISION QA DATA
CBP Moni- * field replicates *
toring (from some labs)
data (REP_NUM=1,2)
CBP QA * field replicates lab replicates
data** (from some labs) (from all labs)
INTER-ORGANIZATION PRECISION QA DATA
CBP inter-organiza- field replicates lab replicates
CSSP*** tion splits
* Data to assess this are not available from this source.
** CBP QA data are kept in separate data sets, available on request. Summaries
are provided below.
*** Coordinated Split Sample Program (CSSP) data are kept in separate data sets,
available on request. See CSSP reports (below) for summaries of the data.
Accuracy estimates in CBP QA data come from two sources: results from
spike samples, and results from Standard Reference Material (SRM)
analyses. Spike samples estimate the percent recovery when a known amount
of the substance being analyzed is added to a water sample. The spike is
usually added in the laboratory, but may also be added in the field to
include more of the analysis process in the estimate. Percent recovery
should be 100% under ideal conditions. Parameters that are analyzed
directly from filters cannot be spiked, so they have no accuracy data from
this source.
SRM analyses are standards prepared by EPA or other laboratories, and are
provided with a "true" concentration. Percent recovery for SRMs
represents the percentage of the true value recovered. SRMs are not
available for all parameters analyzed in the CBP. Accuracy estimates are
reported in two different places (Table 8, "Summary of CBP Accuracy
Estimates").
t
Guide to Using CBP Water Quality Monitoring Data Page 114
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t
Table 8. Summary of CBP Accuracy Estimates.
SOURCE OF ESTIMATE-
DATA Laboratory Field Standard Reference
SOURCE spikes spikes Materials (SRMs)
WITHIN-ORGANIZATION ACCURACY QA DATA
CBP Moni- * *
toring data
CBP QA Percent recovery Percent recovery
data** (from all labs) (from some labs)
INTER-ORGANIZATION ACCURACY QA DATA
CBP Percent recovery * Percent recovery
CSSP*** (from all labs) (from all labs)
* Data to assess this are not available from this source.
** CBP QA data are kept in separate data sets, available on request. Summaries
are provided below.
*** Coordinated Split Sample Program (CSSP) data are kept in separate data sets,
available on request. See CSSP reports (below) for summaries of the data.
More detailed definitions of QA terms, and data submission guidelines for
QA data, are given in the Chesapeake Bay Program Data Management Plan (CBP
1992a).
B. Within-organization QA data
Field QA Data
Field precision is estimated with field replicates. The CBP monitoring
data base contains two different types of field replicates, both
identified by the variable REP_NUM.
Field splits:
MDE includes field splits of single grab samples in its regular
submission to the data base. Stations and layers which have field
splits are: CB1.1 - B, CB2.2 - S, CB3.3 - B, CB4.1W - S, CB4.2E - B,
CB4.3C - AP, CB4.4 - B, and CBS.2 - S. Field replicates (separate
grabs) are not collected.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 115
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VIMS began collecting field splits with Cruise 96 (first April 1989
cruise). The mean, but not the separate results from each of the
splits are submitted in the regular monitoring data sets, and the
corresponding QA data set has the value of one replicate and the
standard deviation with REP_TYPE = "FLD".
Field replicates:
ODD collects true field replicate samples (separate grabs) at a
specified station (CB7.3, then CB7.4N) and includes these as
individual observations in both its monitoring and QA data submis-
sions.
For parameters that involve digestion (TOP, TON, PHOSP, TKNW, TKNF), field
replicates or splits always receive separate digestion. They are treated
as separate samples once they are collected in the field. See DAITS #3
for details.
The QA data sets may also contain field split results from ODU and VIMS.
ODU sometimes does lab replicates on each of the two field replicates;
these are on separate lines for the same date and station, with the
variable FIELDREP = 1 or 2.
Laboratory QA Data
Laboratory precision and accuracy are estimated with laboratory replicates
and laboratory spike samples. Ten percent of samples coming into the
laboratory (including the field replicates) are randomly selected (on a
parameter by parameter basis) for lab replicate analysis. See DAITS #3
for details. For those lab replicates, the mean of the two results is the
value reported in the monitoring and QA data bases. The mean, standard
deviation, and sample size is reported in the QA data base. Sometimes
more than two replicates are analyzed.
Any number in the monitoring data base, whether a single sample, or one or
both field replicate/split samples, may actually be a mean of two lab
replicates, if the sample was randomly selected in the lab to be
replicated.
For parameters that involve digestion (TOP, TP direct, TON direct, TKNW,
TKNF), lab replicates can be created before or after the digestion. VIMS
and ODU have always created the replicates before digestion, while CBL
creates them after it. This tends to make CBL results from lab replicates
less variable for these parameters, and would also tend to make CBL
results for field replicates more variable than CBL results for lab
replicates. This should be kept in mind when reviewing the "Summary of
Laboratory QA data" below. For several parameters analyzed from filters
(PHOSP direct, POC direct, PON direct, TSS, and CHLA) the "lab" replicates
actually represent duplicate filters from samples split in the field,
since no sample filtration is done in the laboratory. See DAITS #3 for
details.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 116
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Laboratory spikes are also performed on 10% of samples for those
parameters that can be spiked. Parameters analyzed directly from a filter
pad cannot be spiked: POC, PON, and CHLA. These parameters get extra
replication at most labs, as duplicate filters. PHOSP is analyzed from a
filter pad but the extract from the pad can be spiked. Percent recovery
can be calculated by two methods, the EPA method and the alternative
method. VIMS and CRL use the EPA method, while CBL and ODU use the
alternative calculation. However, CBL and ODU percent recovery results
are recalculated by the EPA method before inclusion in the CBPCC QA data
base. See DAITS #17 for details.
Laboratory precision and accuracy data are submitted to the CBPCC in QA
data sets. Table 9, "Summary of Laboratory Quality Assurance (QA) data,"
gives descriptive statistics for estimates of precision and accuracy for
each laboratory. These are summarized over all years for which we had
consistent data: June 1984-May 1985 for OEP/CRL, and October 1986-December
1991 for CBL, VIMS, and ODU. CBL submitted QA data from May 1985 onward,
but it was summarized here starting October 1986 to make their summary
comparable to the ones for VIMS and ODU. The CBP did not require QA data
submission until October 1986.
The definitions of the parameters are, using PARAM to represent the name
of the parameter (NH4, etc.):
PARAM_S : Standard deviation of laboratory duplicates (n-1 or df in the
denominator)
PARAM_CV: Percent coefficient of variation of laboratory duplicates,
calculated from (PARAM_S/PARAM)*100.
PARAM_P: Percent recovery of a laboratory spike sample, calculated by EPA
method:
PARAM_P = [ (Concentration of mixture of spike + sample) - (concentration
of sample before spiking) ] / (Known concentration of spike) * 100; in CBP
names, PARAM_P = [PARAM_SK - PARAM]/PARAM_C * 100.
See the "Chesapeake Bay Program Data Management Plan" (CBP 1992a) for
details.
Descriptive statistics are given over all years to save space; in most
cases, the precision and accuracy both improved over time (smaller PARAM_S
and PARAM_CV values, and PARAM_P values closer to 100%) . Annual summaries
of these data, and the raw data, are available from CBPCC staff on
request.
3/93 Guide to Using CBP Water Quality Monitoring Data Page 117
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Table 9. Sunmary of Laboratory Quality Assurance Data.
MD Office of Environmental Programs (OEP)/Central Regional Laboratory (CRL) QA
data, June 1984 through May 1985
Variable
N
Mean
Std Dev
Minimum
Maximum
TP_S
TP_CV
TDP_S
TDP_CV
PO4F_S
PO4F_CV
TKNW_S
TKNW_CV
TKNF_S
TKNF_CV
NO23_S
NO23_CV
NO2_S
N02_CV
NH4_S
NH4_CV
TOC_S
TOC_CV
DOC_S
DOC_CV
SI_S
SI_CV
TSS_S
TSS_CV
TP_P
TDP_P
PO4F_P
TKNW_P
TKNF_P
NO23_P
NO2_P
NH4_P
TOC_P
DOC_P
SI_P
103
103
71
71
42
40
134
134
62
62
76
76
50
50
92
92
132
132
122
122
106
106
49
49
103
101
112
170
93
111
111
111
133
135
106
0.00076
1.80379
0.00032
1.62359
0.00390
2.95793
0.02321
6.37104
0.01723
5.08508
0.00234
0.97375
0.00020
1.48739
0.00199
2.06928
0.15576
6.02664
0.10066
5.40420
0.00263
0.35017
1.22714
11.25835
103.06796
104.45545
101.77679
103.74118
101.79570
103.27027
106.10811
110.11712
92.70677
93.71852
98.61321
0.00121
2.06803
0.00050
2.92626
0.01493
4.86494
0.04436
9.18353
0.01549
4.66545
0.00267
1.49683
0.00045
3.44316
0.00256
3.38579
0.22377
8.33919
0.15792
8.71940
0.00432
0.66110
1.24344
13.72170
2.87744
3.85363
7.35424
12.75175
10.92221
5.75712
3.98258
6.39565
14.47400
15.96575
5.15765
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000.
0.00000
0.00000
0.00000
0.00000
0.00000
97.00000
97.00000
88.00000
74.00000
70.00000
85.00000
94.00000
96.00000
62.00000
58.00000
88.00000
0.00700
7.36842
0.00200
14.28571
0.07400
20.00000
0.48000
93.02326
0.05800
18.64952
0.01000
9.33333
0.00200
14.28571
0.01000
17.85714
1.30000
48.14815
1.13000
51.36364
0.02100
3.70370
4.00000
66.66667
112.00000
114.00000
117.00000
156.00000
143.00000
116.00000
117.00000
125.00000
124.00000
140.00000
111.00000
3/93
Guide to Using CBP Water Quality Monitoring Data Page 118
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t
Table 9 (continued). Summary of Laboratory Quality Assurance Data.
Chesapeake Biological Laboratory (CBL) QA data, Oct. 86 through Dec. 91
Variable
N
Mean
Std Dev
Minimum
Maximum
TP_S*
TP_CV*
TDP_S*
TDP_CV*
PHOSP_S
PHOSP_CV
PO4F_S
PO4F_CV
TDN_S*
TDN_CV*
PON_S
PON_CV
TKNW_S*
TKNW_CV*
TKNF_S*
TKNF_CV*
N023_S
NO23_CV
NO2_S
N02_CV
NH4_S
NH4_CV
TOC_S
TOC_CV
DOC_S
DOC_CV
POC_S
POC_CV
SI_S
SI_CV
TSS_S
TSS_CV
TP_P
TDP_P
PO4F_P
TDN_P
TKNW_P
TKNF_P
NO23_P
N02_P
NH4_P
TOC_P
DOC_P
SI_P
60
60
400
390
303
303
400
400
291
291
573
568
54
54
72
72
379
378
369
368
367
367
75
75
404
404
574
573
376
376
431
431
51
346
386
302
22
11
380
389
388
88
382
382
* Lab replicates
0.00075
2.11948
0.00048
4.57147
0.00084
3.92604
0.00045
6.58526
0.00527
0.71163
0.00904
3.82973
0.01584
2.98740
0.01316
4.24527
0.00281
1.83962
0.00200
4.68426
0.00190
5.12282
0.18366
4.63636
0.07409
2.69971
0.04625
3.80713
0.00997
2.13077
0.67522
8.97367
101.37173
100.59062
99.06718
99.51096
119.34560
134.63422
99.90162
98.98532
107.62848
105.16957
106.60108
98.89557
were split after
0.00058
1.96714
0.00072
7.58138
0.00135
5.05758
0.00051
7.98822
0.00917
0.98808
0.03083
5.27268
0.01460
3.04242
0.01096
5.21735
0.00763
3.46845
0.03300
10.21043
0.00294
11.74351
0.38813
7.17926
0.11228
3.87134
0.08846
4.71091
0.04307
5.72167
0.90683
11.46129
4.18213
5.94015
7.40074
4.28727
30.79436
24.39354
5.32877
4.71491
12.19326
14.97587
13.19551
6.20797
digestion;
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
p. 00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
91.39785
84.21053
67.82842
79.02098
61.29032
93.65079
71.33333
66.73804
55.55556
63.92786
25.60000
77.46479
see above for
0.00212
8.31890
0.00860
47.14045
0.01138
33.96886
0.00300
56.60377
0.12020
7.60759
0.57590
64.58333
0.07071
16.22868
0.04950
28.28427
0.12876
30.45685
0.63410
85.71429
0.03000
85.71429
3.18198
52.42143
1.01823
33.14563
1.04652
55.66585
0.71000
60.68376
8.10000
100.00000
115.00000
143.47826
164.51613
118.86792
206.45161
163.49206
115.77061
119.04762
168.25397
190.58116
194.00000
135.71429
explanation.
3193
Guide to Using CBP Water Quality Monitoring Data Page 119
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Table 9 (continued) . Summary of Laboratory Quality Assurance Data.
Virginia Institute of Marine Science (VIMS) QA data, Oct. 86 through Dec. 91
Variable
N
Mean
Std Dev
Minimum
Maximum
TP_S
TP_CV
TDP_S
TDP_CV
PHOSP_S
PHOSP_CV
PO4F_S
PO4F_CV
TDN_S
TDN_CV
PON_S
PON_CV
TKNW_S
TKNW_CV
TKNF_S
TKNF_CV
NO23_S
NO23_CV
NO2_S
N02_CV
NH4_S
NH4_CV
DOC_S
DOC_CV
POC_S
POC_CV
SI_S
SI_CV
TSS_S
TSS_CV
CHLA_S
CHLA_CV
TP_P
TDP_P
PO4F_P
TDN_P
TKNW_P
TKNF_P
N023_P
NO2_P
NH4_P
DOC_P
SI_P
113
113
542
542
425
425
532
532
423
423
514
514
102
102
49
49
517
517
534
534
522
522
1044
1044
507
507
519
519
293
293
248
248
92
403
412
316
123
67
409
457
430
227
459
Note : Excluding
0.00115
3.67094
0.00069
6.31473
0.00121
7.29754
0.00014
3.52779
0.01750
4.31195
0.01052
8.63402
0.01306
2.80935
0.01564
4.50531
0.00038
1.90045
0.00009
2.26867
0.00061
2.45657
0.08078
2.39702
0.05382
7.05440
0.00146
0.93563
1.86619
13 .15424
1.05080
11.85803
98.19564
97.12045
96.02280
94 .70812
101.05165
102.31345
96.85741
103.39530
96.27411
98.58908
95.23879
REP_TYPE=nFLD"
0.00120
3.76497
0.00096
10.47104
0.00164
9.84897
0.00039
11.48506
0.01574
3.75075
0.01319
9.70290
0.01150
2.57593
0.01584
4.52627
0.00074
5.38549
0.00025
7.41796
0.00150
7.02653
0.07939
2.34822
0.06293
9.94466
0.00240
2.95791
2.84525
19.97452
1.41033
12.86288
6.34232
10.79982
6.86227
14.44001
12.34995
11.45564
7.49625
10.11891
10.26046
7.24144
5.95093
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
83.00000
60.00001
70.00000
52.00001
46.99999
80.80002
67.49998
52.49999
58.12498
76.50001
74.73309
(field replicates) . No TOC
0.00707
15.71348
0.00707
70.71066
0.01131
53.03302
0.00283
77.13891
0.10748
19.79899
0.14991
66.55122
0.05515
14.82642
0.10041
29.53210
0.00552
45.75397
0.00156
80.81221
0.02687
86.67759
0.86974
20.06321
0.53174
78.06968
0.02546
40.40609
23.47594
172.69717 .
9:65133
79.86743
128.99997
168.18179
112.49998
147.33331
138.79999
136.39996
121.87498
147.49997
149.37497
115.33334
113.75000
data.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 1:20
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t
Table 9 (continued) . Summary
Old Dominion University (ODU)
Variable N Mean
of Laboratory
QA data, Oct.
Std Dev
Quality Assurance Data.
86 through Aug. 91
Minimum Maximum
TP_S
TP_CV
TDP_S
TDP_CV
PHOSP_S
PHOSP_CV
PO4F_S
PO4F_CV
TDN_S
TDN_CV
PON_S
PON_CV
TKNW_S
TKNVJ_CV
TKNF_S
TKNF_CV
NO23_S
N023_CV
N02_S
NO2_CV
NH4_S
NH4_CV
TOC_S
TOC_CV
DOC_S
DOC_CV
POC_S
POC_CV
SI_S
SI_CV
TSS_S
TSS_CV
CHLA_S
CHLA_CV
TP_P
TDP_P
PO4F_P
TDN_P
TKNW_P
TKNF_P
NO23_P
NO2_P
NH4_P
TOC_P
DOC_P
SI_P
66
66
263
263
295
295
295
295
292
292
1386
1386
66
66
69
69
319
319
231
231
387
387
144
144
1386
1386
1518
1518
302
302
69
69
52
52
66
244
274
270
66
70
222
247
233
76
436
234
0.00090
2.25572
0.00144
3.67391
0.00102
6.23528
0.00053
4.39250
0.00933
4.25255
0.00993
9.42919
0.02346
4.90787
0.02603
7.90252
0.00030
2.01867
0.00004
1.23718
0.00046
1.96333
0.18381
6.89472
0.08982
3.82111
0.04518
7.74970
0.00168
1.23631
1.16488
10.78004
0.91203
16.45009
102 .77273
101.14098
98.10584
103.28000
97.68939
99.16071
98.21489
93.59514
97.37891
93.41165
96.92708
103.82707
0.00114
3.00805
0.01537
8.68346
0.00120
6.31651
0.00083
7.60687
0.00883
4.48706
0.02825
10.09803
0.01715
4.29839
0.01704
5.28860
0.00053
4.34988
0.00009
3.27706
0.00090
5.03606
0.23440
7.23438
0.09065
3.97536
0.04371
6.83906
0.00334
3.92045
1.30274
11.45561
0.96373
14.15011
3.73670
3.02915
4.64423
11.97678
8.05403
6.52379
4.87407
13.85810
6.18257
22.80876
13.15385
19.59614
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
95.00000
90.00000
85.00000
57.00000
75.00000
86.25000
83.00000
35.00000
76.25000
50.00000
50.00000
83.39752
0.00566
13.25825
0.24942
111.34612
0.00849
37.14096
0.00707
70.71068
0.05020
24.74874
0.65054
132.82957
0.07778
28.28427
0.06364
24.59502
0.00445
38.49002
0.00042
18.44626
0.00923
64.85133
1.90919
47.14045
0.77782
32.63570
0.50301
47.14045
0.02087
38.19176
6.01041
51.73952
4.22850
50.91169
110.00000
111.00000
115.00000
134.50000
112.50000
112.50000
110.50000
111.00000
115.71429
157.14286
185.71429
209.58494
3/93
Guide to Using CBP Water Quality Monitoring Data Page 121
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C. Inter-organization QA data
Early Split Sample and Co-located Sample Results
VIMS and ODU exchanged field split samples from 1985 through 1989; these
results were analyzed in Bergstrom (1989), "Split sample water quality
results from laboratories participating in the Chesapeake Bay Program:
1985-1989." MDE laboratories were not involved in mainstem splits until
the Coordinated Split Sample Program (CSSP) began.
The original design of the Mainstem Monitoring Program included co-located
sampling by MDE and VIMS at station CBS.3, near the Maryland-Virginia
line. The goal was to
maximize the synoptic nature of our samples. . .by having the
Virginia and Maryland teams meet at a common station in mid-Bay off
the Potomac and sample the vertical profile as nearly together as
possible and then proceed, respectively, down and up the estuary
(CBP 1985) .
In practice, the MDE and VIMS research vessels usually did not meet at
CBS.3, due to boat scheduling problems and weather delays. As a result,
the "co-located" CBS.3 samples were usually collected at slightly
different sites at different times, sometimes on different days. Because
the "co-located" sample results contained variability due to different
places and times of sampling, members of the Analytical Methods and
Quality Assurance Workgroup (AMQAW) decided on 4/24/90 that they should
not be used to assess inter-organization agreement. Since it was not
aiding the original goal of synoptic sampling, VIMS discontinued sampling
at CBS.3 in July 1990. To avoid duplicated data, the VIMS results from
CBS.3 are not routinely included in data requests for CBP data, but are
available from the CBPCC on request.
Coordinated Split Sample Program (CSSP)
This was organized in 1988 to include all the laboratories in the
Chesapeake Bay Program (CBP). Mainstem laboratories have analyzed split
samples quarterly since June 1988, sending mainstem samples to the three
mainstem laboratories (CBL, VIMS, and ODU) as well as the two main
tributary laboratories (Maryland Department of Health and Mental Hygiene,
MDHMH, and Virginia Division of Consolidated Laboratory Services, DCLS).
See AMQAW 1991, "Chesapeake Bay Coordinated Split Sample Program
Implementation Guidelines, Revision 3" for details. The results are used
to identify any parameters and laboratories where inter-organization
agreement needs to be increased; several special comparison studies, and
several minor method changes, have been done to increase inter-
organization agreement in water quality results. Regular reports are
produced summarizing the results (AMQAW 1992) .
3/93 Guide to Using CBP Water Quality Monitoring Data Page 122
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t
V. RELATED DOCUMENTATION
Analytical Methods and Quality Assurance Workgroup (AMQAW) . 1991. Chesapeake Bay
Coordinated Split Sample Program (CSSP) Implementation Guidelines, Revision 3.
CBP/TRS 58/91, Chesapeake Bay Program, Annapolis, MD.
Analytical Methods and Quality Assurance Workgroup (AMQAW) . 1992. Chesapeake Bay
Coordinated Split Sample Program Annual Report, 1990-1991. CBP/TRS 76/92,
Chesapeake Bay Program, Annapolis, MD.
Analytical Methods and Quality Assurance Workgroup (AMQAW). In draft.
Recommended guidelines for sampling and analyses in the Chesapeake Bay Monitoring
Program. Chesapeake Bay Program, Annapolis, MD.
Aspila, I. et al. 1976. A semi -automated method for the determination of
inorganic, organic, and total phosphate in sediments. Analyst 101:187-197.
Batiuk, R. , et al. 1992. Chesapeake Bay Submerged Aquatic Vegetation Habitat
Requirements and Restoration Goals: A Technical Synthesis. CBP/TRS 52/92,
Chesapeake Bay Program, Annapolis, MD.
Bergstrom, P. 1989. Split sample water quality results from laboratories
participating in the Chesapeake Bay Program: 1985-1989. CBP/CSSP Report Series
#l, Chesapeake Bay Program, Annapolis, MD.
Bergstrom, P. 1992. Adjusting helix Kjeldahl nitrogen results: Maryland
Chesapeake Bay Mainstem Water Quality Monitoring Program, 1984-1985. CBP/TRS
44/92, Chesapeake Bay Program, Annapolis, MD.
Chesapeake Bay Program (CBP). 1983a. Chesapeake Bay: A profile of environmental
change. Main document (200 pp) and Appendices. US Environmental Protection
Agency (EPA), Philadelphia, PA.
Chesapeake Bay Program (CBP). 1983b. Chesapeake Bay: A framework for action.
Main document (186 pp) and Appendices. US Environmental Protection Agency (EPA) ,
Philadelphia, PA.
Chesapeake Bay Program (CBP). 1985. Monitoring 1984: A first report from the
Chesapeake Bay Program Monitoring Subcommittee. Chesapeake Bay Program,
Annapolis, MD. *
Chesapeake Bay Program (CBP). 1989. Chesapeake Bay Basin Monitoring Program
Atlas, Vol I. Water Quality and Other Physiochemical Monitoring Programs.
CBP/TRS 34/89, Chesapeake Bay Program, Annapolis, MD.
Chesapeake Bay Program (CBP). 1990. The Chesapeake Bay Segmentation Scheme.
CBP/TRS 38/90, Chesapeake Bay Program, Annapolis, MD.
Chesapeake Bay Program (CBP). 1992a. Chesapeake Bay Program Data Management
Plan. Chesapeake Bay Program, Annapolis, MD.
3/93
Guide to Using CBP Water Quality Monitoring Data Page 123
-------
Chesapeake Bay Program (CBP). 1992b. Trends in Nitrogen in the Chesapeake Bay
(1984-1990). CBP/TRS 68/92, Chesapeake Bay Program, Annapolis, MD.
Computer Sciences Corporation (CSC) . 1991. Trends in Phosphorus in the Chesapeake
Bay (1984-1990). CBP/TRS 67/91, Chesapeake Bay Program, Annapolis, MD.
D'Elia, C., et al. 1986. Methodological comparisons for nitrogen and
chlorophyll determinations in estuarine water samples. University of Maryland,
Center for Estuarine and Environmental Studies, Publication UMCEES-CBL-86-55.
D'Elia, C., et al. 1987. Nitrogen and phosphorus determinations in estuarine
waters: a comparison of methods used in Chesapeake Bay Monitoring. CBP/TRS 7/87,
Chesapeake Bay Program, Annapolis, MD.
Magnien, R. 1986. A comparison of estuarine water chemistry analysis on the
filtrate from two types of filters. Maryland Office of Environmental Programs,
Balt imore, MD.
Salley, B., et al. 1992. A comparison of two methods of measuring dissolved
organic carbon. Special Scientific Report #128, Virginia Institute of Marine
Science (VIMS), Gloucester Point, VA.
Taylor, J. 1987. Quality assurance of chemical measurements. Lewis Publishers,
Inc, Chelsea, MI.
U.S. Environmental Protection Agency. 1983. Methods for Chemical Analysis of
Water and Wastes. Environmental Monitoring and Support Laboratory, Cincinnati,
OH.
Zimmermann, C. 1991. Estuarine nutrient analyses: A comparison of sample
handling techniques and analyses of carbon, nitrogen, phosphorus, and chlorophyll
a. Report submitted to EPA through Technology Applications, Inc. by Chesapeake
Biological Laboratory, Solomons, MD.
t
3/93 Guide to Using CBP Water Quality Monitoring Data Page 124
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