822F93009
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460 .
OFFICE OF
WATER
NOTE;
SUBJECT: Additional Material for the Water Quality Standards
Handbook
FROM: DavidTK. Sabock, Chief
Water Quality Standards Branch
TO: Recipients of the Water Quality Standards Handbook
Second Edition
On October 1, 1993, the Acting Assistant Administrator for
Water issued the Office of Water PolicyandTechnical Guidance on
Interpretation and Implementation of Acniatic Life Metals Criteria.
Since the policy document was signed too late for inclusion in
the Water Quality Standards Handbook - Second Edition, the complete
policy document is attached and should i>e kept with the Handbook.
Later this fiscal year, you will receive an update to the Handbook/
to be inserted in this section, reflecting the policy document.
If you have any further questions on the Handbook or the
attached guidance, contact me at 202-260-1315 or the appropriate
technical contacts listed on page 7 of the cover memorandum of the
guidance.
Attachment
PriHUdoHKtcycUdPaptr
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
. OCT I 5 1993
Dear Environmental Advocate:
OFFICE OF
WATER
On October 1, 1993,1 signed a memorandum regarding the Office of Water's Policy
and Technical Guidance on Interpretation and Implementation of-Aquatic Life Metals
Criteria. This memorandum covers a number of areas including the expression of aquatic
life criteria, total maximum daily loads, National Pollution Discharge Elimination System
permits and enforcement, effluent monitoring, and ambient monitoring. The policy and
guidance in this document considers comments received from the U.S. Environmental
Protection Agency (EPA) Regional Offices, recommendations made to EPA by the
participants in a meeting held in January 1993 in Annapolis, Maryland, and public comments
in the June 8, 1993, Federal Register notice requesting general public comments on the
Annapolis meeting recommendations. As stated in the enclosed memorandum, we will
continue to issue f uidance as more information becomes available.
Sincerely you
Martha G. Prothro,
Acting Assistant Adminisbator
Enclosure
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UNrTEO STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460 -
OCT 1 893
OFFCCOF
WATER
MEMORANDUM
SUBJECT: Office of Water Policy and Technical Guidance on Interpretation and
'Implementation of Aquatic Life Metals Criteria
FROM: Martha G.Prothro:^
Acting Assistant Administrator for Water
TO: Water Management Division Directors
Environmental Services Division Directors
Regions I-X
Introduction
The implementation of metals criteria is complex due to the site-specific nature of
metals toxicity. We have undertaken a number of activities to develop guidance in this area,
notably the Interim Metals Guidance, published May 1992, and a public meeting of experts
held in Annapolis, MD, in January 1993. This memorandum transmits Office of Water
(OW) policy and guidance on the interpretation and implementation of aquatic life criteria for
the management of metals and supplements my April 1, 1993, memorandum on the same
subject. The issue coven a number of areas including the expression of aquatic life criteria;
total maximum daily- loads (TMDLs), permits, effluent.monitoring, and compliance; and
ambient monitoring. The memorandum coven each in turn.- Attached to this policy
memorandum are three guidance documents with additional technical details. They are:
Guidance Document on Expression of Aquatic Life Criteria as Dissolved Criteria
(Attachment 42), Guidance Document on Dynamic Modeling and Translators (Attachment
f3), and Guidance Document on Monitoring (Attachment *4). These will be supplemented
as additional data become available. (See the schedule in Attachment f 1.)
Since metals toxicity is significantly affected by site-specific factors, it presents a
number of programmatic challenges. Factors that must be considered in the management of
metals in the aquatic environment include: toxicity specific to effluent chemistry; toxicity
specific to ambient water chemistry; different patterns of toxicity for different metals;
evolution of the state of the science of metals toxicity, fate, and transport; resource
limitations for monitoring, analysis, implementation, and research functions; concerns
regarding some of the analytical data currently on record due to possible sampling and
analytical contamination; and lack of standardized protocols for clean and ultradean metals
analysis. The States have the key role in the risk management process of balancing these
factors in the management of water programs. The site-specific nature of this issue could •*
perceived as requiring a permit-by-permit approach to implementation. However, we believe
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that this guidance can be effectively implemented on a broader level, across any waters with
roughly the same physical and chemical characteristics, and recommend that we work with
the States with that perspective in mind.
Expression of Aquatic Life Criteria
o Dissolved vs. Total Recoverable Metal
A major issue is whether, and how, to use dissolved metal concentrations ("dissolved
metal") or total recoverable metal concentrations ("total recoverable metal") in setting State
water quality standards. In the past, States have used both approaches when applying the
same Environmental Protection Agency (EPA) criteria numbers. .Some older criteria
documents may have facilitated these different approaches to interpretation of the criteria
• because the documents were somewhat equivocal with regards to analytical methods. The
May 1992 interim guidance continued the policy that either approach was acceptable.
It is now the policy of the Office of Water that the use of dissolved metal to set and
measure compliance with water quality standards is the recommended approach, because
dissolved meal more closely approximates the bioavailable fraction of metal in the water
column than does total recoverable metal. This conclusion regarding metals bioavailability is
supported by a majority of the scientific community within and outside the Agency. One
reason is that a primary mechanism for water column toxicity is adsorption at the gill surface
which requires metals to be in the dissolved form.
The position mat the dissolved metals approach is more accurate has been questioned
because it neglects the possible toxicity of paniculate metal It is true that some studies have
indicated mat paniculate metals appear to contribute to the toxicity of metals, perhaps
because of factors such as desoiption of metals at the gill surface, but these same studies
indicate the toxicity of paniculate metal is substantially less man that of dissolved metal.
Furthermore, any error incurred from excluding the contribution of paniculate metal
will generally be compensated by other factors which make criteria conservative. For
example, metals in toxicity tests are added as simple salts to relatively clean water. Due to
the likely presence of a significant concentration of metals binding agents in many discharges
and ambient waters, metals in toxicity tests would generally be expected to be more
bioavailabile than metals in discharges or in ambient waters.
If total recoverable metal is used for the purpose of water quality standards,
compounding of factors due to the lower bioavailability of paniculate meal and lower
bioavailability of metals as they are discharged may result in a conservative water quality
standard. The use of dissolved metal in water quality standards gives a more accurate result.
However, the majority of the participants at the Annapolis meeting felt that total recoverable
measurements in ambient water had some value, and that exceedences of criteria on a total
recoverable basis were an indication that metal loadings could be a stress to the ecosystem,
particularly in locations other than the water column.
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The reasons for the potential consideration of total recoverable measurements include
risk management considerations not covered by evaluation of water column toxicity. The
ambient water quality criteria are neither designed nor intended 10 protect sediments, or to
prevent effects due to food webs containing sediment dwelling organisms. A risk manager,
however, may consider sediments and food chain effects and may decide to take a •'- .
conservative approach for metals, considering that metals are very persistent chemicals. This
conservative approach could include the use of total recoverable metal in water quality
standards. However, since consideration of sediment impacts is not incorporated into the
criteria methodology, the degree of conservatism inherent in .the total recoverable approach is
unknown. The uncertainty of metal impacts in sediments stem from the lack of sediment
criteria and an imprecise understanding of the fate and transport of metals. EPA will
continue to pursue research- and othe^activitie* to close these knowledge gaps.
Until the scientific uncertainties are better resolved, a range of different risk
management decisions can be justified. EPA recommends that State water quality standards
be based on dissolved metal. (See the paragraph below and the attached guidance for
technical details on developing dissolved criteria.) EPA will also approve a State risk
management decision to adopt standards based on total recoverable metal, if those standards
are otherwise approvable as a matter of law.
o Dissolved Criteria
In the toxicity tests used to develop EPA metals criteria for aquatic life, some fraction
of the metal is dissolved white some fraction is bound to paniculate matter. The present
criteria were developed using total recoverable metal measurements or measures expected to
give equivalent results in toxicity tests, and are articulated as total recoverable. Therefore,
in order to express the EPA criteria as dissolved, a total recoverable to dissolved correction
factor must be used. Attachment 12 provides guidance for calculating EPA dissolved criteria
from the published total recoverable criteria. The data expressed, as percentage metal,.
dissolved are presented as recommended values and ranges. However, the choice within
ranges is a State risk management decision. We have recently supplemented the data for
copper and are proceeding to further supplement the data for copper and other metals. As
testing is completed, we will make this information available and this is expected to reduce
the magnitude of the ranges for some of the conversion factors provided. We also strongly
encourage the application of dissolved criteria across a watershedVor waterbody, as
technically sound and the best use of resources.
o Site-Specific Criteria Modifications
While the above methods will correct some site-specific factors affecting metals
toxicity, further refinements are possible. EPA has issued guidance (Water Quality
Standards Handbook, 1983; Guidelines for Deriving Numerical Aquatic Site-Specific Water
Quality Criteria by Modifying National Criteria, EPA-600/3-H4-099, October 1984) for three
site-specific criteria development methodologies: recalculation procedure, indicator species
procedure (also known as the water-effect ratio (WER)) and resident species procedure.
Only the first two of these have been widely used.
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In the National Toxics Rule (57 FR 60848, December 22, 1992), EPA identified the
WER as an optional method for site-specific criteria development for certain metals. EPA
committed in the NTR preamble to provide guidance on determining the WER. A draft of
this guidance has been circulated to the States and Regions for review and comment As
justified by water characteristics and as recommended by the WER guidance, we strongly
encourage the application of the WER across a watershed or waterbody as opposed to
application on a discharger by discharger basis, as technically sound and an efficient use of
resources.
In order to meet current needs, but allow for changes suggested by protocol users,
EPA will issue the guidance as "interim." EPA will accept WERs developed using this
guidance, as well as by using other scientifically defensible protocols. OW expects the
interim WER guidance will be issued in the next two months.
Total Maximum Daily Loads fTMPLsl and National Pollutant Discharge Elimination System
ffJPDES> Permits
o Dynamic Water Quality Modeling
Although not specifically part of the reassessment of water quality criteria for metals,
dynamic or probabilistic models are another useful tool for implementing water quality
criteria, especially for those criteria protecting aquatic life. These models provide another
way to incorporate site-specific data. The 1991 Technical Support Document for Water
Quality-based Toxics Control (TSD) (EPA/505/2-90-001) describes dynamic, as well as static
(steady-state) models. Dynamic models make the best use of the specified
duration, and frequency of water quality criteria and, therefore, provide a more accurate
representation of the probability that a water quality standard exceedence will occur. In
contrast, steady-state models make a number of simplifying, worst case assumptions which
makes them less complex and less accurate than- dynamic models.
Dynamic models have received increased attention over the last few yean as a result
of the widespread belief that steady-state modeling is over-conservative due to
environmentally conservative dilution assumptions. This belkf has led to the misconception
that dynamic models will always lead to less stringent regulatory controls (e.g., NPDES
effluent limits) than steady-state models, which is not true in every application of dynamic
models. EPA considers dynamic models to be a more accurate approach to implementing
water quality criteria and continues to recommend their use. Dynamic modeling does require
commitment of resources to develop appropriate data. (See Attachment 13 and the TSD for
details on the use of dynamic models.)
o Dissolved-Total Metal Translators
Expressing water quality criteria as the dissolved form of a metal poses a need to be
able to translate from dissolved metal to total recoverable metal for TMDLs and NPDES
permits. TMDLs for metals must be able to calculate: (1) dissolved metal in order to
ascertain attainment of water quality standards, and (2) total recoverable metal in order to
achieve mass balance necessary for permitting purposes.
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EPA's NPDES regulations require that limits of metals in permits be stated as total
recoverable in most cases (see 40 CFR §122.45(c)) except when an effluent guideline
specifies the limitation in another form of the metal, the approved analytical methods
measure only dissolved metal, or the permit writer expresses a metals limit in another form
(e.g., dissolved, valent, or total) when required to carry out provisions of the dean Water
Act. This is because the chemical conditions in ambient waters frequently differ substantially
from those in the effluent, and there is no assurance mat effluent paniculate metal would not
dissolve after discharge. The NPDES rule does not require that State water quality standards
be expressed as total recoverable; rather, the rule requires permit writers to translate between
different metal forms in the calculation of the permit limit so that a total recoverable limit
can be established. Both the TMDL and NPDES uses of water quality criteria require the
ability to translate between dissolved metal and total recoverable metal. Attachment 13
provides methods for this translation.
Guidance on Monitoring
o Use of Clean Sampling and Analytical Techniques
In assessing waterbodies to determine the potential for toxicity problems due to
metals, the quality of the data used is an important issue. Metals data are used to determine
attainment status for water quality standards, discern trends in water quality, estimate
background loads for TMDLs, calibrate fete and transport models, estimate effluent
concentrations (including effluent variability), assess permit compliance, and conduct
research. The quality of trace level metal data, especially below 1 ppb, may be
compromised due to contamination of samples during collection, preparation, storage, and
analysis. Depending on the level of metal present, the use of "clean" and "ultraclean"
techniques for sampling and analysis may be critical to accurate data for implementation of
aquatic life criteria for metals. ...
The magnitude of the contamination problem increases as the ambient and effluent
metal concentration decreases and, therefore, problems are more likely in ambient
measurements. "Clean" techniques refer to those requirements (or practices for sample
collection and handling) necessary to produce reliable analytical data in the part per billion
(ppb) rangeV "Ultraclean* techniques refer to those requirements or practices necessary to
produce reliable analytical data in the part per trillion (ppt) range. Because typical
concentrations of metals in surface waters and effluents vary from one metal to another, the
effect of contamination on the quality of metals monitoring data varies appreciably.
We plan to develop protocols on the use of dean and ultra-clean techniques and are
coordinating with the United States Geological Survey (USGS) on this project, because USGS
has been doing work on these techniques for some time, erpetiaUy the sampling procedures.
We anticipate that our draft protocols for clean techniques will be available in late calendar
year 1993. The development of comparable protocols for ultra-dean techniques is underway
and will be available in 1995. In developing these protocols, we will consider the costs of
these techniques and will give guidance as to the situations where their use is necessary.
Appendix B to the WER guidance document provides some general guidance on the use of
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clean analytical techniques. (See Attachment #4.) We recommend that this guidance be used
by States and Regions as an interim step, while the clean and ultra-clean protocols are being
developed. _ -
o . Use of Historical Data - -
The concerns about metals sampling and analysis discussed above raise corresponding
concerns about the validity of historical data. Data on effluent and ambient metal
itrations are collected by a variety of organizations including Federal agencies (e.g.,
wvuwcni
EPA, ITSGS), State pollution control agencies and health departments, local government
agencies, municipalities, industrial dischargers, researchers, and others. The data are
collected fora variety of purposes as discussed above.
_ Concern about the reliability of the sample collection and analysis procedures is
greatest where they have been used to monitor very low level metal concentrations.
Specifically, studies have shown data sets with contamination problems during sample
collection and laboratory analysis, that have resulted in inaccurate measurements. For
example, in developing a TMDL for New York Harbor, some historical ambient data showed
extensive metals problems in the harbor, white other historical ambient data showed only
limited metals problems. Careful resampling and analysis in 1992/1993 showed the latter
view was correct. The key to producing accurate data is appropriate quality assurance (QA)
and quality control (QC) procedures. We believe that most historical data for metals,
collected and analyzed with appropriate QA and QC at levels of 1 ppb or higher, are
reliable. The data used in development of EPA criteria are also considered reliable, both
because they meet the above test and because the toxitity test solutions are created by adding
known amounts of metals.
With respect to effluent monitoring reported by an NPDES permittee, the permittee is
responsible for collecting and reporting quality data on a Discharge Monitoring Report
(DMR). Permitting authorities should continue to consider the information reported to be
true, accurate, and complete as certified by the permittee. Where the permittee becomes
aware of new information specific to the effluent discharge that questions the quality of
previously submitted DMR data, the permittee must promptly submit that information to the
permitting authority. The permitting authority will consider all information submitted by the
permittee in determining appropriate enforcement responses to monitoring/reporting and
effluent violations. (See Attachment *4 for additional details.)
Summary
The management of metals in the aquatic environment is complex. The science
supporting our technical and regulatory programs is continuing to evolve, here as in all
4,-eas. The policy and guidance outlined above represent the position of OW and should be
incorporated into ongoing program operations. We do not expect that ongoing operations
would be delayed or deferred because of this guidance.
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If you have questions concerning this guidance, please contact Jim Hanlon, Acting
Director, Office of Science and Technology, at 202-260-5400. If you have questions on
specific details of the guidance, please contact the appropriate OW Branch Chief. The
Branch Chiefs responsible for the various areas of the water quality program are: Bob April
(202-260-6322, water quality criteria), Elizabeth Fellows (202-260-7046, monitoring and data
issues), Russ Kinerson (202-260-1330, modeling and translators), Don Brady (202-260-7074,
Total Maximum Daily Loads), Sheila Frace (202-260-9537, permits), Dave Sabock
(202-260-1315, water quality standards), Bill Telliard (202-260-7134, analytical methods)
and Dave Lyons (202-260-8310, enforcement).
Attachments
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ATTACHMENT *\
TECHNICAL GUIDANCE FOR METALS
Schedule of Upcoming Guidance -
Water-effect Ratio Guidance - September 1993
Draft "Clean" Analytical Methods - Spring 1994
Dissolved Criteria - currently being done; as testing is completed, we will release the
updated percent dissolved data
Draft Sediment Criteria for Metals - 1994
Final Sediment Criteria for Metals -1995
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ATTACHMENT Wl
GUIDANCE DOCUMENT
ON DISSOLVED CRITERIA
Expression of Aquatic Life Criteria
October 1993
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10-1-93
Percent Dissolved in Aquatic Toxicity Tests on Metals
The attached table contains all the data that were found
concerning the percent of the total recoverable metal that was
dissolved in aquatic toxicity tests. This table is intended to
contain-the available data that are relevant to the conversion of
EPA's aquatic life criteria for metals from a total recoverable
basis to a dissolved basis. (A factor of 1.0 is used to convert
aquatic life criteria for metals that are expressed on the basis
of the acid-soluble measurement to criteria expressed on the
basis of the total recoverable measurement.) Reports by Grunvald
(1992) and Brungs et al. (1992) provided.references to many of
the documents in which pertinent, data were.found. Each document
was obtained and examined to determine whether it contained
useful data.
"Dissolved11 is defined as metal that passes through a 0.45-pm
membrane filter. If otherwise acceptable, data that were
obtained using 0.3-^m glass fiber filters and 0.1-pm membrane
filters were used, and are identified in the table; these data
did not seem to be outliers.
Data were used only if the metal was in a dissolved inorganic
form when it was added to the dilution water. In addition, data
were used only if they were generated in water that would have
been acceptable for use as a dilution water in tests used in the
derivation of water quality criteria for aquatic life; in
particular, the pH had to be between 6.5 and 9.0, and the
concentrations of total organic carbon (TOC) and total suspended
solids (TSS) had to be below 5 mg/L. Thus most data generated
using river water would not be used.
Some data were not used for other reasons. Data presented by
Carroll et al. (1979) for cadmium were not used because 9 of the
36 values were above 150%. Data presented by Davies et al.
(1976) for lead and Holcombe and Andrew (1978) for zinc were not
used because "dissolved11 was defined on the basis of
polarography, rather than filtration.
Beyond this, the data were not reviewed for quality. Horowitz et
al. (1992) reported that a number of aspects of the filtration
procedure might affect the results. In addition, there might be
concern about use of "clean techniques" and adequate QA/QC.
Each line in the table is intended to represent a separate piece
of information. All of the data in the table were determined in
fresh water, because no saltwater data were found. Data are
becoming available for copper in salt water from the Mew York
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Harbor study; based on the first set of tests, Hansen (1993)
suggested that the average percent of the copper that is
-dissolved in sensitive saltwater tests.is in the range of 76 to
' 82 percent. . .
-A thorough investigation of the percent of total recoverable
metal that is dissolved in toxicity tests might'attempt to
determine if the percentage is .affected by test technique
(static, renewal, flow-through), feeding (were the test animals
•fed and, if so, what food and how much), water quality
characteristics (hardness, alkalinity, pR, salinity), test
organisms (species, loading), etc.
The attached table also gives the freshwater criteria
concentrations (CMC and CCC) because percentages for total
recoverable concentrations much (e.g., more than a factor of 3)
above or below the CMC and CCC are-likely to be less relevant.
When a criterion is expressed as a hardness equation, the range
given extends from a hardness of.50 mg/L to a hardness of 200
mg/L.
The following is a summary of the available information for each
metal:
Arsenicfill)
The data available indicate that the percent dissolved is about
100, but all the available data are for concentrations that are
much higher than the CMC and CCC.
Cadmium
Schuytema et al. (1984) reported that "there were no real
differences'* between measurements of total and dissolved cadmium
at concentrations of 10 to 80 ug/L (pH • 6.7 to 7.8, hardness --
25 mg/L, and alkalinity * 33 mg/L); total and dissolved
concentrations were said to be "virtually equivalent".
The CMC and CCC are close together and only range from 0.66 to
8.6 ug/t> The only available data that are known to be in the
range of the CMC and CCC were determined with a glass fiber
filter. The percentages 'that are probably most relevant are 75,
92, 89, 78, and 80.
ChromiumfTIT1
The percent dissolved decreased as the total recoverable
concentration increased, even though the highest concentrations
reduced the pH substantially. The percentages that are probably
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most relevant to the CMC are 50-75, whereas the percentages that
are probably most relevant to the CCC are 86 and 61.
ChromiumfVTi .-.---. -
The data available indicate that the percent dissolved is about
100, but all the available data are for concentrations*that are
much ftigher than the CMC and CCC.
Copper
Howarth and Sprague (1978) reported that the total and dissolved
concentrations of copper were."little,different" except when the
total copper concentration was above 500 ug/L at hardness » 360
zng/L and pH * 8 or 9. Chakoumakos et al. (1979) found that the
percent dissolved depended more on alkalinity than on hardness,
pH, or the total recoverable concentration of copper.
Chapman (1993) and Lazorchak (1987) both found that the addition
of daphnid food affected the percent dissolved very little, even
though Chapman used yeast-trout chow-alfalfa whereas Lazorchak
used algae in most tests, but yeast-trout chow-alfalfa in some
tests. Chapman (1993) found a low percent dissolved with and
without food, whereas Lazorchak (1987) found a high percent
dissolved with and without food. All of Lazorchak's values were
in high hardness water; Chapman's one value in high hardness
water was much higher than his other values.
Chapman (1993) and Lazorchak (1987) both compared the effect of
food on the total recoverable LC50 with the effect of food on the
dissolved LC50. Both authors found that food raised both the
dissolved LC50 and the total recoverable LC50 in about the same
proportion, indicating thatr food did not raise the total
recoverable LC50 by sofbing metal onto food particles; possibly
the food raised both LCSOs by (a) decreasing the toxicity of
dissolved metal, (b) forming nontoxic dissolved complexes with
the metal, or (c) reducing uptake.
The CMC and CCC are close together and only range from 6.5 to 34
ug/L. The percentages that are probably most, relevant are 74,
95, 95, 73, 57, 53, 52, 64, and 91.
Lead
The data presented in Spehar et al. (1978) were from Holcombe et
al. (1976). Both Chapman (1993) and Holcombe et al. (1976) found
that the percent dissolved increased as the total recoverable
concentration increased. It would seem reasonable to expect more
precipitate at higher total recoverable concentrations and
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therefore a lower percent dissolved at higher concentrations.
The incr«a«a in parcant dissolved with incraasing concentration
night ba dua to a lowering of the pH as more natal is addad if
the stock solution was acidic.
Tha percentages that are probably nost relevant to the CMC ara 9,
18, 25, 10, 62, 68, 71, 75, 81, and-95, whereas the percentages
that ara probably nost relevant to the CCC ara 9 and 10.
Mercury
Tha only percentage that is available is 73, but it is for a
concentration that is nuch higher than the CMC.
Nickel
The percentages that ara probably nost relevant to the CMC are
88, 93, 92, and 100, whereas the only percentage that is probably
relevant to the CCC is 76.
Selenium
No data ara available.
Silver
There is a CMC, but not a CCC. Tha percentage dissolved seen* to
be greatly reduced by the food used to feed daphnida, but not by
tha food used to faad fathead ainnows. Tha percentages that are
probably nost relevant to tha CMC ara 41, 79, 79, 73, 91, 90, and
93.
zinc
Tha CMC and CCC ara close together and only range fron 59 to 210
ug/L. Tha percentages that are probably nost relevant ara 31,
77, 77, *9, 94, 100, 103, and 96.
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Recommended Values (%)A and Ranges of Measured Percent Dissolved
Considered Most Relevant in Fresh Water
Metal £M£ " CCC
Recommended " Recommended
Value (*\ fBanaa *1 Value (*1 rRange
Arsenic (III)
Cadmium
Chromium (III)
Chromium (VI)
•Copper
Lead
Mercury
Nickel
Selenium
Silver
Zinc
95
85
85
95
85
50
85
85
NAB
85
85
100-104*
75-92
50-75
100*
52-95
9-95
73*
88-100
NAC
41-93
31-103
95
85
85
95
85
25
NAB
85
NAB
YY°
85
100-104*
75-92
61-86
100*
52-95
9-10
NAB
76
NAC
YY°
31-103
A The recommended values are based on current knowledge and are
subject to change as more data becomes available.
* All available data are for concentrations that are much higher
than the CMC.
c NA - Mo data are available.
.•-".">'•'..
0 YY - A CCC is not available, and therefore cannot be adjusted.
E NA - Bioaccumulative chemical and not appropriate to adjust to
percent dissolved.
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Conch.* Percent
fuq/L> Dia«.» n£ Spades" fi££! Eflfid UflJaL. AUu fiU Raf.
ARSENIC f nil (Freshwater: CCC • 190 ug/L; CMC » 360 ug/L)
600-15000 104 5 ? ? ? 48 41 7.6 Lima et al. 1984*
12600 100 3 FM F No 44 43 7.4 Spehar and Fiandt 1986
CADMIUM (Freshwater: CCC - 0.66 to 2.0 ug/L; CMC - 1.8 to 8.6 ug/L)11
o.i6 41 ? DM R Yes 53 46 7.6 Chapman 1993
0'.28 75 ? DM R Yes 103 83 7.9 Chapman 1993
0.4-4.0 92° ? CS F No 21 19 . 7.1 Finlayson and Verrue 1982
13 89 3 FM F No 44 43 7.4 Spehar and Fiandt 1986
15-21 96 8 FM S No 42 31 7.5 Spehar and Carlson 1984
42 84 4 FM 8 No 45 41 7.4 Spehar and Carlson 1984
10 78 ? DM S No 51 38 7.5 Chapman 1993
35 77 ? DM S No 105 88 8.0 Chapman 1993
51 59 ? DM S No 209 167 8.4 Chapman 1993
6.80 80 8 ? S No 47 44 7.5 Call et al. 1982
3-232 90" 5 ? F ? 46 42 7.4 Spehar et al. 1978
450-6400 70 5 FM F No 202 157 7.7 Pickering and Cast 1972
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CHROMIUM rim (Freshwater: CCC « 120 to 370 ug/L; CMC = 980 to 3100 ug/L)*
5-13
19-495
>1100
42
114
16840
26267
27416
58665
94 ? :;>.
86 ? -"
50-75 ?
54 ?
61 ?
26 ?
32 ?
27 ?
23 ?
CHROMIUM (VI) (Freshwater
>2b,000
43,300
COPPER
10-30
40-200
30-100
100-200
20-200
40-300
10-80
100 1
99.5 4
(Freshwater: CCC
74 ?
78 ?
79 ?
82 ?
86 ?
87 ?
89 ?
SG
SG
SG
DM
DM
DM
DM
DM
DM
: ccc
FM,GF
FM
- 6.5
CT
CT
CT
CT
CT
CT
CT
F
F
F
R
R
S
S
S
S
» 11
F
F
to 21
F
F
F
F
F
F
F
?
?
No
Yes
Yes
No
No
No
No
ug/L; CMC
Yes
No
25
25
25
206
52
<51
110
96
190
- 16
220
44
ug/L; CMC » 9
No
No
No
No
No
No
No
27
154
74
192
31
83
25
24
24
24
166
45
9
9
10
25
Ug/L)
214
43
.2 to
20
20
23
72
78
70
169
7.3
7.2
7.0
8.2
7.4
6.31
6.7
6.01
6.21
7.6
7.4
34 ug/L)
7.0
6.8
7.6
7.0
8.3
7.4
8.5
Stevens and Chapman 198
Stevens and Chapman 198
Stevens and Chapman 198
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Adelman and Smith
Spehar and Flandt
p
Chakoumakos et al.
Chakoumakos et al.
Chakoumakos et al.
i .1
Chakoumakos et al.
Chakoumakos et al.
Chakoumakos et al.
Chakoumakoa et «i.
1976
1986
1979
1979
1979
1979
1979
1979
1470
-------
300-1300
100-400
3-41
12-911
18-19
201
50
17 51
5-52
6-80
6.7
35
13
16
51
32
33
39
25-84
17
120
15-90
12-162
28-58
26-59
56,101
92
94
125-167
79-84
95
95
96
91
••'82*
83°
57
43
73
57
39
S3
52
64
96
91
88
74
80"
85
79
86
?
?
2
i
2
1
2
2
?
?
?
?
?
?
?
?
?
?
14
6
14
19
?
6
7
2
CT
CT
CD
CD
DA
DA
FM
FM •
FM
CS
DM
DM
DM
DM
DM
DM
DM
DM
FM,GM
DM
SG
?
BG
DM
DM
DM
F
F
R
R
S
R
S
R
F
F
S
S
R
R
R
S
S
8
S
S
8
S
F
R
R
R
No
No
Yes
Yes
No
No
No
No
YesL
No
No
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
YesL
No
Yes"
Yes11
195
70
31
31
52
31
52
31
47
21
49
48
211
51
104
52
105
106
50
52
48
48
45
168
168
168
160
174
38
38
55
38
55
38
43
19
37
39
169
44
83
45
79
82
40
43
47
47
43
117
117
117
7.0
8.5
7.2
7.2
7.7
7.2
7.7
7.2
8.0
7.1
7.7
7.4
8.1
7.6
7.8
7.8
7.9
8.1
7.0
7.3
7.3
7.7
7-8
8.0
8.0
8.0
Chakoumakos et al. 1979
Chakotmakos et al. 1979
Carlson et al.' 1966a,b
Carlson et al. 1986a,b,
Carlson et al. I986b
Carlson et.al. I986b
Carlson et al. 1986b
Carlson et al. I986b
Llnd et al. 1978
Finlayson and Verrue 1982
Chapman 1993
chapman 1993
Chapman 1993
Chapman 1993 '
Chapman 1993
Chapman 1993
Chapman 1993' '
Chapman 1993
Hammermeister et al. 1983
Hammermelster et al. 1983
Hammermeister et al. 1983
call et al. 1982
Benolt 1975
Lazorchak 1987
Lazorchak 1987
Lazorchak 1987
8
-------
96
86
FM
F
NO
44
43 7.4 Spehar and Fiandt 1986
160
230-3000
94
>69->79
LEAD (Freshwater:
17
181
193
612
952
1907
7-29
34
58
119
235
474
4100
2100
220-2700
580
9
18
25
29
33
-38
10
62"
68M
71"
75M
81"
82"
79
96
95
1 FM
? CR
CCC * 1.3 to
? DM
? DM
? DM
? DM
? DM
? DM
? EZ
? BT
? BT
? BT
? BT
? BT
? BT
7 FM
14 FM,GM,DM
14 SG
S
F
7.7
R
R
R
S
S
S
R
F
F
F
F
F
F
F
S
S
No
No
ug/L; CMC
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
No
No
No
No
203
17
•= 34
52
102
151
50
100
150
22
44
44
44
44
44
44
44
49
51
171
13
to 200
47
86
126
--
—
••••
—
43
43
43
43
43
43
43
44
48
8.2
7.6
ug/L)F
7.6
7.8
8.1
_- _
— — —
7.2
7.2
7.2
7.2
7.2
7.2
7.4
7.2
7.2
Geckler et al. 1976
Rice and Harrison 1983
Chapman 1993
Chapnan 1993
Chapnan 1993
Chapnan 1993
Chapaan 1993
Chapnan 1993
JRB Associates 1983
Hoicombe et al. 1976
Holconbe et al. 1976
Holconbe et al. 1976
Holconbe et al. 1976
Holconbe et al. 1976
Holconbe et al. 1976
Spehar and Fiandt 1986
Hannemeister et al. 1983
Hannerneister et al. 1983
MERCURYfin (Freshwater: CMC - 2.4 ug/L)
172 73 1 FM F No
44 43 7.4 Spehar and Fiandt 1986
-------
NICKEL (Freshwater: CCC - 88 to 280 ug/L; CMC - 790 to 2500 ug/L)*
21
ISO
578
645
1809
1940
2344
4000
81
76
87
88
93
92
100
? DM
? DM
? •*? DM
? DM
? DM
? DM
? DM
R
R
R
S
S
S
S
Yes
Yes
Yes
No
No
No
No
51
107
205
54
51
104
100
49
87
161
43
44
84
84
7.4
7.8
8.1
7.7
7.7
8.2
7.9
90
PK
NO
21
Chapman 1993
Chapaan 1993
Chapaan 1993 '
Chapnan 1993
Chapaan 1993
Chapman 1993
Chapaan 1993
( i
JRB Associates 1983"
SELENIUM (FRESHWATER: CCC - 5 ug/L; CMC - 20 ug/L)
No data are available.
SILVER (Freshwater: CMC - 1.2 to 13 ug/L; a CCC is not available)
0.19
9.98
4.0
4.0
3
2-54
2-32
4-32
5-89
6-401
74 "t
13 1
41 't
11 1
79 \
79 1
73 1
91 1
90 1
93 1
• DM
P DM
r DM
r DM
r FM
r FM
? FM
P FM
? FM
? FM
S
S
8
8
S
8
S
8
S
S
No
Yes
No
Yes
No
Yes0
No
No
No
No
47
47
36
36
51
49
50
48
120
249
37
37
25
25
49
49
49
49
49
49
7.6
7.5
7 .0
7.0
8.1
7.9
8.1
8.1
8.2
8.1
Chapman 1993
Chapaan 1993
Nebeker et
Nebeker et
UWS 1993
UWS 1993
UWS 1993
UWS 1993
UWS 1993
UWS 1993
al. 1983
al. 1983
i
10
-------
ZINC (Freshwater: CCC - 59 to 190 ug/L; CMC 65 to 210 ug/I,)F
52
62
191
356
551
741
71
18-2731
167'
180
188-3931
551
40-500
1940
5520
<4000
>4000
160-400
240
31
77
77
74
78
76
71-129
81-107
99
94
100
100
95°
100
83
90
70
103
96
?
?
»'$
?
?
?
2
2
2
1
2
1
?
?
?
?
?
13
13
DM
DM
DM
DM
DM
DM
CD
CD
CD
CD
FM
FM
CS
AS
AS
FM
FM
FM,GM,DM
SG
R
R
R
S
S
S
R
R
R
S
R
S
F
F
F
F
F
S
S
Yes
Yes
Yes
No
No
No
Yes
Yes
No
No
No
No
No
No
No
No
No
No
NO
211
104
52
54
105
196
31
31
31
52
31
52
21
20
20
204
204
52
49
169
83
47
47
85
153
38
38
38
55
38
55
19
12
12
162
162
43
46
8.2
7.8
7.5
7.6
8.1
8.2
7.2
7.2
7.2
7.7
7.2
7.7
7.1
7.1
7.9
7.7
7.7
7.5
7.2
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Chapman 1993
Carlson et al.
Carlson et al.
Carlson et al.
Carlson et al.
Carlson et al.
Carlson et al.
: Finlayson and
,
Sprague 1964
Sprague 1964
Mount 1966
Mount 1966
Hammermeister
Hammermeister
I986b
1986b
1986b
1986b
1986b
1986b
Verrue 1982
t \
et al. 1983
et al. 1983
A Total recoverable concentration.
• Except as noted, a 0.45-jim membrane filter was used.
11
-------
c Number of paired comparisons.
0 The abbreviations used are:
AS
BT
CD
CR
cs
CT
DA
Atlantic salmon
Brook trout
Ceriodjiphnia dubia
Crayfish
Chinook salmon
Cutthroat trout
Daphnids
DM
EZ
FM
GF
GH
PK
SG
Daphnia maqna
Elassoma gon.atum
Fathead minnow
Goldfish
Gammarid
Palaemonetes kadiakenaiS
Salmq aairdneri
B Tha abbreviations used are:
8 - static
R » renewal
F • flow- through
i
\
' The two numbers are for hardnesses of 50 and 200 mg/L, respectively.
u A 0.3-^m glass fiber filter was used.
M A 0.10-pm membrane filter was used. __. '
1 The pH was below 6.5.
1 The dilution water was a clean river water with TSS and TOC below 5 ag/L.
K Only limited information is available concerning this value.
L It is assumed that the solution that was filtered was from the test chambers that
contained fish and food.
M The food was algae. :r
N The food was yeast-trout chow-alfalfa.
0 The food was frozen adult brine shrimp.
12
-------
References
Adelman,. I.R., and L.L. Smith, Jr. 1976. standard Test Fish
Development:. Part I. Fathead Minnows fPim«phal«a pronalasi and
Goldfish rcaraaaiua auratuai as Standard Fish in Bioassays and
Their Reaction to Potential Reference Toxicants. EPA-600/3-76-
06la. National Technical Information Service, Springfield, VA.
Page 24.
Benoit, D.A. 1975. Chronic Effects of Copper on Survival,
Growth, and Reproduction of the Bluegill (Lepoais aacrochlrus).
Trans. An. Fish. Soc. 104:353-358.
Brungs, H.A., T.S. Holderman, and M.T. Southerland. 1992.
Synopsis of Hater-Effect Ratics -for-Heavy Metals as Derived for
Site-Specific Water Quality Criteria.
Call, D.J., L.T. Brooke, and D.D. Vaishnav. 1982. Aquatic
Pollutant Hazard Assessments and Development of a Hazard
Prediction Technology by Quantitative Structure-Activity
Relationships. Fourth Quarterly Report. University of
Wisconsin-Superior, Superior, WZ. .
Carlson, A.R., H. Nelson, and D. Hammermeister. 1986a.
Development and Validation of Sxte-Specific Water Quality
Criteria for Copper. Environ. Toxicol. Chem. 5:997-1012.
Carlson, A.R., H. Nelson, and D. Hammermeister. 1986b.
Evaluation of Site-Specific Criteria for Copper and Zinc: An
Integration of Metal Addition Toxicity, Effluent and Receiving
Water Toxicity, and Ecological Survey Data. EPA/600/S3-86-026.
National Technical Information Service, Springfield, VA.
Carroll, J.J., S.J. Ellis, and W.S. Oliver. 1979. Influences of
Hardness Constituents on the Acute Toxicity of Cadmium to Brook
Trout (Salvelinus tontlnalis).
Chakoumakos, C., R.C. Russo, and R.v. Thurston. 1979. Toxicity
of Copper to Cutthroat Trout (Saloo clariki) under Different
Conditions of Alkalinity, pH, and Hardness. Environ. Sci.
Techno!V 13:213-219.
Chapman, G.A. 1993. Memorandum to C. Stephen. June 4.
Davies, P.H., J.P. Goettl, Jr., J.R. Sinley, and N.F. Smith.
1976. Acute and Chronic Toxicity of Lead to Rainbow Trout Salao
grairdneri, in Hard and Soft Water. Water Res. 10:199-206.
Finlayson, B.J., and K.M Verrue. 1982. Toxicities of Copper,
Zinc, and Cadmium Mixtures to Juvenile Chinook Salmon. Trans.
Am. Fish. Soc. 111:645-650.
13
-------
Geckler, J.R., W.B. Horning, T.M. Neiheisel, Q.H. Pickering, E.L.
Robinson, and C.E. Stephan. 1976. Validity of Laboratory Tests
for Predicting Copper Toxicity in Streams. EPA-600/3-76-lie.
National Technical Information Service, Springfield, VA. Page
118.
Grunwald, D. 1992. Metal Toxicity Evaluation: Review, Results,
and Data Base Documentation.
Hammermeister, D., c. Northcott, L. Brooke, and D. Call. 1983.
Comparison of Copper', Lead and Zinc Toxicity to Four Animal
Species in Laboratory and ST. Louis River Water. University of
Wisconsin-Superior, Superior, WI.
Hansen, D.J. 1993. Memorandum to C.E. Stephan. April 15.
Holcombe, G.W., D.A. Benoit, E.N. Leonard, and J.M. McKim. 1976.
Long-Term Effects of Lead Exposure on Three Generations of Brook
Trout (5alvelijius iontin&lis). J. Fish. Res. .Bd. Canada 33:1731-
1741.
Holcombe, G.W., and R.W. Andrew. 1978. The Acute Toxicity of
Zinc to Rainbow and Brook Trout. EPA-600/3-78-094. National
Technical Information Service, Springfield, VA.
Horowitz, A.J., K.A. Elrick, and M.R. Colberg. 1992. The Effect
of Membrane Filtration Artifacts on Dissolved Trace Element
Concentrations. Water Res. 26:753-763.
Howarth, R.S., and J.B. Sprague. 1978. Copper Lethality to
Rainbow Trout in Waters on Various Hardness and pH. Water Res.
12:455-462.
JRB Associates. 1983. Demonstration of the Site-specific
Criteria Modification Process: Selser's Creek. Ponchatoula,
Louisiana.
Lazorchak, J.M. 1987. The Significance of Weight Loss of
Daohnia maema Straus During Acute Toxicity Tests with Copper.
Ph.D. Thesis.
Lima, A.R., C. Curtis, D.E. Hammermeister, T.P. Markee, C.E.
Northcott, L.T. Brooke. 1984. Acute and Chronic Toxicities of
Arsenic(III) to Fathead Minnows, Flagfish, Daphnids, and an
Amphipod. Arch. Environ. Contam. Toxicol. 13:595-601.
Lind, D., K. Alto, and S. Chatterton. 1978. Regional Copper-
Nickel Study. Draft.
Mount, D.I, 1966. The Effect of Total Hardneas and pH on Acut«
Toxicity of Zinc to Fish. Air water Pollut. Int. J. 10:49-56.
14
-------
Nebeker, A.V., c.K. McAuliffe, R. Mshar, and D.G. Stevens. 1983.
Toxicity of Silver to Steelhead and Rainbow Trout, Fathead
Minnows, and Daphnia magna. Environ, toxicol. Chem. 2:95-104.
Pickering, Q.P., and M.H. Cast. 1972. Acute and Chronic
Toxicity of Cadmium to the Fathead Minnow (Pimephales promela*).
J. Fish. Res. Bd. Canada 29:1099-1106.
Rice, D.W., Jr., and F.L. Harrison. 1983. The Sensitivity of
Adult, Embryonic, and Larval Crayfish Procaobams clarJcii to
Copper. NUREG/CR-3133 or UCRL-53048. National Technical
Information Service, Springfield, VA.
Schuytema, G.S., P.O. Nelson, K.W. Malueg, A.V. Nebeker, O.F.
Krawczyk, A.K. Ratcliff, and J.H. Gakstatter. 1984. Toxicity of
Cadmium in Water and: Sediment Slurrie* to .Daphnia magna.
Environ. Toxicol. Chem. 3:293-308.
Spehar, R.L., R.L. Anderson, and.J.T. Fiandt. 1978. Toxicity
and Bioaccumulation of Cadmium and Lead in Aquatic Invertebrates.
Environ. Pollut. 15:195-208.
Spehar, R.L., and A.R. Carlson. 1984. Derivation of Site-
Specific Hater Quality Criteria for Cadmium and the St. Louis
River Basin, Duluth, Minnesota. Environ. Toxicol. Chem. 3:651-
665.
Spehar, R.L., and J.T. Fiandt. 1986. Acute and Chronic Effects
of Water Quality Criteria-Based Metal Mixtures on Three Aquatic
Species. Environ. Toxicol. Chem. 5:917-931.
Sprague, J.B. 1964. Lethal Concentration of Copper and Zinc for
Young Atlantic Salmon. J. Fish. Res. Bd. Canada 21:17-9926.
Stevens, D.G., and G.A., Chapman. 1984. Toxicity of Trivalent
Chromium to Early Life Stages of Steelhead Trout. Environ.
Toxicol. Chem. 3:125-133.
University of Wisconsin-Superior. 1993. Preliminary data from
work assignment 1-10 for Contract No. 68-C1-0034.
15
-------
ATTACHMENT #3
GUIDANCE DOCUMENT
ON DYNAMIC MODELING AND TRANSLATORS
August 1993
TtHfll Maximum Daily Loads fTMDLs) and Permits
o Dynamic Water Quality Modeling
Although not specifically part of the reassessment of water quality criteria for metals,
dynamic or probabilistic models are another useful tool for implementing water quality
criteria, especially those for protecting aquatic life. Dynamic models make best use of the
specified magnitude, duration, and frequency of water quality criteria and thereby provide a
more accurate calculation of discharge impacts on ambient water quality. In contrast, steady-
state modeling is based on various simplifying assumptions which makes it less complex and
less accurate than dynamic modeling. Building on accepted practices in water resource
engineering, ten yean ago OW devised methods allowing the use of probability distributions
in place of worst-case conditions. The description of these models and their advantages and
disadvantages is found in the 1991 Technical Support Document for Water Quality-based
Toxic Control (TSD).
Dynamic models have received increased attention in the last few yean as a result of
the perception that static modeling is over-conservative due to environmentally conservative
dilution assumptions. This has led to the misconception that dynamic models will always
justify less stringent regulatory controls (e.g. NPDES effluent limits) than static models. In
effluent dominated waters where the upstream concentrations are relatively constant,
however, a dynamic model will calculate a more-stringent wasteload allocation than will a
steady state model. The reason is that die critical low flow required by many State water
quality standards in effluent dominated streams occurs more frequently than once every three
years. When other environmental factors (e.g. upstream pollutant concentrations) do not
vary appreciably, then the overall return frequency of the steady stale model may be greater
than once jo three yean. A dynamic modeling approach, on the other hand, would be more
stringent, allowing only a once in three year return frequency. As a result, EPA considers
dynamic models to be a more accurate rather than a less stringent approach to implementing
water quality criteria.
The 1991 TSD provides recommendations on the use of steady state and dynamic
water quality models. The reliability of any modeling technique greatly depends on the
accuracy of the data used in the analysis. Therefore, the selection of a model also depends
upon The data. EPA recommends that steady state wasteload allocation analyses generally be
used where few or no whole effluent toxiciry or specific chemical measurements are
available, or where daily receiving water flow records are not available. Also, if staff
resources are insufficient to use and defend the use of dynamic models, then steady state
-------
models may be necessary. If adequate receiving water flow and effluent concentration data
are available to estimate frequency distributions, EPA recommends that one of the dynamic
-wasteload allocation modeling techniques.be used to derive wasteload allocations which will
more exactly maintain water quality .standards. The minimum data required for input into
dynamic models include at least 30 years of-river flow data and one year of effluent and
ambient pollutant concentrations.
o Dissolved-Total Metal Translators
When water quality criteria are expressed as the dissolved form of a metal, there is a
need to translate TMDLs and NPDES permits to and from the dissolved form of a metal to
the total recoverable form. TMDLs for toxic metals must be able to calculate 1) the
dissolved metal concentration in order to ascertain attainment of water quality standards and
2) the total recoverable metal concentration in order to achieve mass balance. In meeting
these requirements, TMDLs consider metals to be conservative pollutants and quantified as
total recoverable to preserve conservation of mass. The TMDL calculates the dissolved or -
ionic species of the metals based on factors such as total suspended solids (TSS) and ambient
pH. (These assumptions ignore the complicating factors of metals interactions with other
metals.) In addition, this approach assumes that ambient factors influencing metal
partitioning remain constant with distance down the river. This assumption probably is valid
under the low flow conditions typically used as design flows for permitting of metals (e.g.,
7Q10, 4B3, etc) because erosion, resuspension, and wet weather loadings are unlikely to be
significant and river chemistry is generally stable. In steady-state dilution modeling, metals
releases may be assumed to remain fairly constant (concentrations exhibit low Variability)
with time.
EPA's NPDES regulations require that metals limits in permits be stated as total
recoverable in most cases (see 40 CFR *122.45(c)). .Exceptions occur when an effluent
guideline specifies the limitation in .another form of the metal or the approved analytical
methods measure only the dissolved form. Also, the permit writer may express a metals
limit in another form (e.g., dissolved, valent, or total) when required, in highly unusual
cases, to cany out die provisions of the CWA.
The preamble to the September 1984 National Pollutant Discharge Elimination System
Permit Regulations states that the total recoverable method measures dissolved metals plus
that portion of solid metals that can easily dissolve under ambient conditions (see 49 Federal
Register 38028, September 26,1984). This method is intended to measure metals in the
effluent that are or may easily become environmentally active, white not measuring metals
that are expected to settle out and remain inert.
The preamble cites, as an example, effluent from an electroplating facility that adds
lime and uses clarifiers. This effluent will be a combination of solids not removed by the
clarifiers and residual dissolved metals. When the effluent from the clarifiers, usually with a
-------
high pH level, mixes with receiving water having significantly lower pH level, these solids
instantly dissolve. Measuring dissolved metals in the effluent, in this case, would
underestimate the impact on the receiving water. .Measuring with the total metals method, on
the other hand, would measure metals that would be expected to disperse or settle out and
remain inert or be covered over. Thus, measuring total recoverable metals in the effluent
best approximates the amount of metal likely to produce water quality impacts.
However, the NPDES rule does not require in any way that State water quality
standards be in the total recoverable form; rather, the rule requires permit writers to consider
the translation between differing metal forms in the calculation of the permit limit so that a
total recoverable limit can be established. Therefore, both the TMDL and NPDES uses of
water quality criteria require the ability to translate from the dissolved form and the total
recoverable form.
Many toxic substances, including metals, have a tendency to leave the dissolved phase
and attach to suspended solids. The partitioning of toxics between solid and dissolved phases
can be determined as a function of a pollutant-specific partition coefficient and the
concentration of solids. This function is expressed by a linear partitioning equation:
1+JT/7SS-10"'
where,
dissolved phase metal concentration,
total metal concentration,
TSS * total suspended solids concentration, and
K* » partition coefficient.
A key assumption of the linear partitioning equation is that the sorption reaction
reaches dynamic equilibrium at the point of application of the criteria; mat is, after allowing
for initial mixing the partitioning of the pollutant between the adsorbed and dissolved forms
can be uaeid at any location to predict the fraction of pollutant in each respective phase.
Successful application of the linear partitioning equation relies on tile selection of the
partition coefficient The use of a partition coefficient to represent the degree to which
toxics adsorb to solids is most readily applied to organic pollutants; partition coefficients for
metals are more difficult to define. Metals typically exhibit more complex speciation and
complexation reactions than organics and the degree of partitioning can vary greatly
depending upon site-specific water chemistry. Estimated partition coefficients can be
determined for a number of metals, but waterbody or site-specific observations of dissolved
and adsorbed concentrations are preferred.
-------
EPA suggests three approaches for instances where a water quality criterion for a
metal is expressed in the dissolved form in a State/s water quality standards:
1. Using clean analytical techniques and field sampling procedures with appropriate
QA/QC, collect receiving water samples and determine site specific values of K^ for
each metal. Use these K< values to 'translate' between total recoverable and
dissolved metals in receiving water. This approach is.more difficult to apply because
it relies upon the availability of good quality measurements of ambient metal
concentrations. This approach provides an accurate assessment of the dissolved metal
fraction providing sufficient samples are collected. EPA's initial recommendation is
that at least four pain of total recoverable and dissolved ambient metal measurements
be made during low flow conditions or 20 pain over aU flow conditions. EPA
suggests that the average of data collected during low flow or the 95th percentile -
highest dissolved fraction for all flows be used. The low flow average provides a
representative picture of conditions during the rare low flow events. The 95th
percentile highest dissolved fraction for all flows provides a critical condition
approach analogous to the approach used to identify low flows and other critical
environmental conditions.
2. Calculate the total recoverable concentration for the purpose of setting the permit
limit. Use a value of 1 unless the permittee has collected data (see i 1 above) to show
that a different ratio should be used. The value of 1 is conservative and will not err
on the side of violating standards. This approach is very simple to apply because it
places the entire burden of data collection and analysis solely upon permitted
facilities. In terms of technical merit, it has the same characteristics of the previous
approach. However, permitting authorities may be faced with difficulties in
negotiating with facilities on the amount of data necessary to determine the ratio and
the necessary quality control methods to assure that the ambient data are reliable.
3. Use the historical data on total tiiipmdcd solids (TSS) in receiving waterbodies at
appropriate design flows and K* values presented in the Technical Guidance Manual
for Performing Waste Load Allocations. BookIL Streams and Riven. EPA-440/4-
84-020 (1984) to "translate" between (total recoverable) permits limits and dissolved
metals in receiving water. This approach is fairly simple to apply. However, these
K< values are suspect due to possible quality assurance problems with the data used to
develop the values. EPA's initial analysis of this approach and these values in one
site indicates that these K* values generally over-estimate the dissolved fraction of
metals in ambient waters (see Figures following). Therefore, although this approach
may not provide an smiratf estimate of the dissolved fraction, the bias in die estimate
is likely to be a conservative one.
EPA suggests that regulatory authorities use approaches f 1 and 12 where States
express their water quality standards in the dissolved form. In mote States where the
standards are in the total recoverable or acid soluble form, EPA recommends mat no
-------
translation be used until the time that the State changes the standards to the dissolved form.
Approach #3 may be used as an interim measure until the data are collected to implement
approach Ml.
-------
Di««olv*d Copp«r Concentration*
-H
45
iv- Measured
-------
M«asur«4 *•• Mod«l«4 Dissolved Cadaiua Concentrations
10
IS
20 25
Sampling Station
30
35
40
Modeled
Measured
-------
*». Mo4«l«4 Diasolvad L«ad Concentration*
1 -^
" M000MO
" Measured
-------
M«Mur«d vs. Nod«l«d Dissolved lUroury concentration*
0.12
0.1
008
006
094
002
• -, Modeled
i
" Measured
10
15
20
25
30
35
40
45
-------
Miek«l Concentrttiona
Modeled
Measured
-------
M«Mur«4 *•. M*c«l«d DUaolvad lino Concentrations
30
25
20
i»
10
W.
,^
25
SampUng Station
b-°n
30 35
40
• Modeled
«> Measured
45
-------
Mtmmur«6 *•• Mo4«l«4 Dl««olv«d Ars«nio Concentrations
2.5
» T
IS
O.S
40
i:
-H
45
it
Measured
-------
ATTACHMENT #4
GUIDANCE DOCUMENT
ON CLEAN ANALYTICAL TECHNIQUES AND MONITORING
October 1993
Guidance on Monitoring
o Use of Clean Sampling and Analytical Techniques
Appendix B to the WER guidance document (attached) provides some general guidance
on the use of clean techniques. The Office of Water recommends that this guidance be used
by States and Regions as an interim step while the Office of Water prepares more detailed
guidance.
o Use of Historical DMR Data
With respect to effluent or ambient monitoring data reported by ah NPDES permittee
on a Discharge Monitoring Report (DMR), the certification requirements place the burden on
the permittee for collecting and reporting quality data. The certification regulation at 40
CFR 122.22(d) requires permittees, when submitting information, to state: "I certify under
penalty of law that this document and all attachments were prepared under my direction or
supervision in accordance with a system designed to assure that qualified personnel properly
gather and evaluate the information submitted. Based on my inquiry of the person or persons
who manage the system, or those persons directly responsible for gathering the information.
the information submitted is, to the best of my knowledge and belief, true, accurate, and
complete. I am aware that there are significant penalties for submitting false information.
possibility of fine and imprisonment for knowing violations."
Pei'mitting authorities should continue to consider the information reported in DMRs
to be true, accurate, and complete as certified by the permittee. Under 40 CFR 122.410K8).
however, as soon as the permittee becomes aware of new information specific to the effluent
discharge that calls into question the accuracy of the DMR data, the permittee must submit
such information to the permitting authority. Examples of such information include a new
finding that the reagents used in the laboratory analysis are contaminated with trace levels of
metals, or a new study that the sampling equipment imparts trace metal contamination. This
information must be specific to the discharge and based on actual measurements rather than
extrapolations from reports from other facilities. Where a permittee submits information
-------
supporting the contention that the previous data are questionable and the permitting authority
agrees with the findings of the information, EPA expects that permitting authorities will
consider such information in determining appropriate enforcement responses.
In addition to submitting the information described above, the permittee also must
develop procedures to assure the collection and analysis of quality data that are true,
accurate, and complete. For example, the permittee may submit a revised quality assurance
plan that describes the specific procedures to be undertaken to reduce or eliminate trace
metal contamination.
-------
10-1-93
Appendix B. Guidance Concerning the Use of "Clean Techniques" and
QA/QC in the Measurement of Traea Metals
Recent information (ShiHer and Boyle 1987; windom et al. 1991)
has raised questions concerning the quality of reported
concentrations of trace metals in both fresh and salt (estuarine-
and marine) surface waters. A lack of awareness of true ambient
concentrations of metals in saltwater and freshwater systems can
be both a cause and a result of the problem. The ranges of
dissolved metals that are typical in surface waters of the United
States away from the immediate influence of discharges (Bruland
1983;. Shillar and Boyle 1985,1987; Trefry et al. 1986; Windom et
al. 1991) are:
Metal Salt water Fresh water
fucr/Ll fua/Ll
Cadmium 0.01 to 0.2 0.002 to 0.08
Copper 0.1 to 3. 0.4 to 4.
Lead 0.01 to 1. 0.01 to 0.19
Nickel 0.3 to 5. 1. to 2.
Silver 0.005 to 0.2
Zinc o.l to 15. 0.03 to 5.
The U.S. EPA (1983,1991) has published analytical methods for
monitoring metals in waters and wastewatars, but these methods
are inadequate for determination of ambient concentrations of
some metals in some surface waters. Accurate and precise
measurement of these low concentrations requires appropriate
attention to seven areas:
l. Use of "clean techniques" during collecting, handling,
storing, preparing, and analyzing samples to avoid
contamination.. •
2. Use of analytical methods that have sufficiently low detection
limits.
3. Avoidance of interference in the quantification (instrumental
analysis) step.
4. Use of blanks to assess contamination.
5. Use^jOf matrix spikes (sample spikes) and certified reference
materials (CRMs) to assess interference and contamination.
6. Use of replicates to assess precision.
7. Use of certified standards.
In a strict sense, the term "clean techniques" refers to
techniques that reduce contamination and enable the accurate and
precise measurement of trace metals in fresh and salt surface
waters. In a broader sense, the term also refers to related
issues concerning detection limits, quality control, and quality
assurance. Documenting data quality demonstrates the amount of
confidence that can be placed in the data, whereas increasing the
sensitivity of methods reduce the problem of deciding how to
-------
interpret results that are reported to be below detection limits.
This appendix ia written for thoaa analytical laboratories that
want guidance concerning wava to lowar detection limits, ineraaaa
precision, and/or ineraaaa accuracy. The ways to achieve these
goals are to increase the .sensitivity of the analytical methods,
decrease contamination, and decrease interference. Ideally,
validation of a procedure for measuring concentrations of metals
in i surface water requires demonstration that agreement can be
obtained using completely different procedures beginning with the
sampling step and continuing through the quantification step
(Bruland et al. 1979), but few laboratories have the resources to
compare two different procedures. Laboratories can, however, (a)
use techniques that others have found useful for improving
detection limits, accuracy, and precision, and (b) document data
quality through use of blanks, spikes, CRMs, replicates, and
standards.
In general, in order to achieve accurate and precise measurement
of a particular concentration, both the detection limit and the
blanks should be less than one-tenth of that concentration.
Therefore, the term "metal-free" can be interpreted to mean that
the total amount of contamination that occurs during sample
collection and processing (e.g., from gloves, sample containers,
labware, sampling apparatus, cleaning solutions, air, reagents,
etc.) is sufficiently low that blanks are less than one-tenth of
the lowest concentration that needs to be measured.
Atmospheric particulates can be a major source of contamination
(Moody 1982; Adeloju and Bond 1985). The term "class-100" refers
to a specification concerning the amount of particulates in air
(Moody 1982); although the specification says nothing about the
composition of the particulates, generic control of particulates
can greatly reduce trace-metal blanks. Except during collection
of samples and initial cleaning of equipment, all handling of
samples, sample containers, labware, and sampling apparatus
should be performed in a class-100 bench, room, or glove box.
Nothing contained or not contained in tftia appendix adda to or
subtracts from anv regulatory raquira-aen'ta set forth in other RPA
document:* concerning aetal analyses. The word "must" is used in
this appendix merely to indicate items that are considered very
important by analytical chemists who have worked to increase
accuracy and precision and lower detection limits in trace-metal
analysis. Some items are considered important because they have
been found to have received inadequate attention in some
laboratories performing trace-metal analyses.
Two topics that are not addressed in this appendix are:
1. The "ultraclean techniques" that are likely to be necessary
when trace analyses of mercury are performed.
2. Safety in analytical laboratories.
-------
Other documents should be consulted if these topics are of
concern.
Avoiding contamination bv use of "clean techniques*
Measurement of trace metals in receiving waters vast take into
account the potential for contamination.during each step in the
process. Regardless of the specific procedures used for
collection, handling, storage, preparation (digestion,
filtration, and/or extraction), and quantification (instrumental
analysis), the general principles of contamination control must
be applied. Some specific recommendations are:
a. Noir-talc latex or class-100 polyethylene gloves must be worn
during all steps from sample collection to analysis. (Talc
seems to be a particular problem with zinc; gloves made with
talc cannot be decontaminated sufficiently.) Gloves should
only contact surfaces that' are metal-free; gloves should be
changed if even suspected of contamination.
b. The acid used to acidify samples for preservation and
digestion and to acidify water for final cleaning of labware,
sampling apparatus, and sample containers must be metal-free.
The quality of the acid used should be better than reagent-
grade. Each lot of acid must be analyzed for the metal(s) of
interest before use.
c. The water used to prepare acidic cleaning solutions and to
rinse labware, sample containers, and sampling apparatus may
be prepared by distillation, deionization, or reverse osmosis,
and must be demonstrated to be metal-free.
d. The work area, including bench tops and hoods, should be
cleaned (e.g., washed and wiped dry with lint-free, class-100
wipes) frequently to remove contamination.
e. All handling of samples in the laboratory, including filtering
and analysis, must be performed in a class-100 clean bench or
a glove box fed by particle-free air or nitrogen; ideally the
clean bench or glove box should be located within a class-100
clean room.: «
f. Labware, reagents, sampling apparatus, and sample containers
must never be left open to the atmosphere; they should be
stored in a class-100 bench, covered with plastic wrap, stored
in a plastic box, or turned upside down on a clean surface.
Minimizing the time between cleaning and using will help
minimize contamination.
g. Separate sets of sample containers, labware, and sampling
apparatus should be dedicated for different kinds of samples,
e.g., receiving water samples, effluent samples, etc.
h. To avoid contamination of clean rooms, samples that contain
very high concentrations of metals and do not require use of
"clean techniques" should not be brought into clean rooms.
i. Acid-cleaned plastic, such as high-density polyethylene
(HOPE), low-density polyethylene (LDPE), or .a fluoroplastic,
must be the only material that ever contacts a sample, except
possibly during digestion for the total recoverable
-------
measurement. (Total recoverable samples can be digested in
some plastic containers.) Even HOPE and LOPE night not be
acceptable for mercury, however.
All labware, sample containers, and sampling apparatus mist be
acid-cleaned before use or reuse.
1. sample containers, sampling apparatus, tubing, membrane
filters, filter assemblies, and other labware Bust be
soaked in acid until metal-free. The amount of cleaning
necessary might depend on the amount of contamination and
the length of time the item will be in contact with
samples. For example, if an acidified sample will be
stored in a sample container for three weeks, ideally the
container should have been soaked in an- acidified metal-
free solution for at least three weeks.
2. It might be desirable to perform initial cleaning, for
which reagent-grade acid may be used, before the items are
allowed into a clean room. For most metals, items should
be either (a) soaked in 10 percent concentrated nitric acid
at 50*C for at least one hour, or (b) soaked in 50 percent
concentrated nitric acid at'room temperature for at least
two days; for arsenic and mercury, soaking for up to two
weeks at 50 •€ in 10 percent concentrated nitric acid might
be required. For plastics that might be damaged by strong
nitric acid, such as polycarbonate and possibly HOPE and
LOPE, soaking in 10 percent concentrated hydrochloric acid,
either in place of or before soaking in a nitric acid
solution, might be desirable.
3. Chromic acid must not be used to clean items that will be
used in analysis of metals.
4. Final soaking and cleaning of sample containers], labware,
and sampling apparatus must be performed in a class-100
clean room using metal-free acid and water. The solution
in an acid bath must be analyzed periodically to
demonstrate that it is metal-free.
5. After labware and sampling apparatus are cleaned, they may
be stored in a clean room in a weak acid bath prepared
using metal-free acid and water. Before use, the items
should be rinsed at least three times with metal-free
water. After the final rinse, the items should be moved
immediately, with the open end pointed down, to a class-100
clean bench. Items may be dried on a class-100 clean
bench; items must not be dried in an oven or with
laboratory towels. The sampling apparatus should be
assembled in a class-100 clean room or bench and double-
bagged in metal-free polyethylene xip-type bags for
transport to the field; new bags are usually mmtal-free.
6. After sample containers are cleaned, they should be filled
with metal-free water that has been acidified to a pH of 2
with metal-free nitric acid (about 0.5 mL per liter) for
storage until use. At the time of sample collection, the
sample containers should be emptied and rinsed at least
twice with the solution being sampled before the actual
-------
sample is placed in the sample container.
Field samples must be collected in a manner that eliminates
-the potential for contamination from the sampling platform,
probes, etc. Exhaust from boats and the direction of wind and
water currents should be taken into account. The people who
collect the samples must be specifically trained on how to
collect field samples. After collection, all handling of
samples in the field that will expose the sample to air must
be performed in a portable class-100 clean bench or glove box.
Samples must be acidified (after/filtration if dissolved metal
is to be measured) to a pH of less than 2, except that the pH
must be less than 1 for mercury. Acidification should be done
in a clean room or bench, and so it might be desirable to wait
and acidify samples in a laboratory rather than in the field.
If samples are acidified in the field, metal-free acid can be
transported in plastic bottles.andipoured:into a plastic
container from which acid can be removed and added to samples
using plastic pipettes. Alternatively, plastic automatic
dispensers can be used.
Such things as probes and thermometers must mot be put in
samples that are to be analyzed for metals. In particular, pH
electrodes and mercury-in-glass thermometers must not be used
if mercury is to be measured. If pH is measured, it must be
done on a separate aliquot.
Sample handling should be minimized. For example, instead of
pouring a sample into a graduated cylinder to measure the
volume, the sample can be weighed after being poured into a
tared container; alternatively, the container from which the
sample is poured can be weighed. (For saltwater samples, the
salinity or density should be taken into account when weight
is converted to volume.)
Each reagent used must be verified to be metal-free. If
metal-free reagents are not commercially available, removal of
metals will probably be necessary.
For the total recoverable measurement,* samples should be
digested in a class-100 bench, not in a metallic-hood. If .
feasible, digestion should be done in the sample container by
acidification and heating.
The longer the time between collection and analysis of
samples, the greater the chance of contamination, loss, etc.
Samples must be stored in the dark, preferably between 0 and
4»C with no air space in the sample container.
Achieving low detection limits
a. Extraction of the metal from the sample can be extremely
useful if it simultaneously concentrates the metal and
eliminates potential matrix interferences. For example,
ammonium 1-pyrrolidinedithiocarbamate and/or diethylammoniua
diethyldithiocarbamate can extract cadmium, copper, lead,
-------
nickel, and zinc (Bruland et al. 1979; Mriagu et al. 1993).
b. The detection limit should be less than ten percent of the
lowest concentration that is to be measured.
Avoiding interferences
a. Potential interferences must be assessed for the specific
instrumental analysis -technique used and each metal to be
-measured. '• "
b. If direct analysis is used, the salt present in high-salinity
saltwater samples is likely to cause interference in most
instrumental techniques.
c. As stated above, extraction of the metal from the sample is
particularly.useful because it simultaneously concentrates the
metal and eliminates potential matrix interferences.
Uaina blanks to assess contamination
a. A laboratory (procedural, method) blank consists of filling a
sample container with analyzed metal-free water and processing
(filtering, acidifying, etc.) the water through the laboratory
procedure in exactly the same way as a sample. A laboratory
blank must be included in each set of ten or fewer samples to
check for contamination in the laboratory, and most contain
less than ten percent of the lowest concentration that is to
be measured. Separate laboratory blanks must be processed for
the total recoverable and dissolved measurements, if both
measurements are performed.
b. A field (trip) blank consists of filling a sample container
with analyzed metal-free water in the laboratory, taking the
container to the site, processing the water through tubing,
filter, etc., collecting the water in a sample container, and
acidifying the water the -same as a field sample. A field
blank must be processed for each sampling trip. Separate
field blanks must be processed for the total recoverable
measurement and for the dissolved measurement, if filtrations
are performed at the site. Field blanks must be processed in
the laboratory the same as laboratory blanks.
Assessing accuracy
a. A calibration curve must be determined for each analytical run
and the calibration should be checked about every tenth
sample, calibration solutions mast be traceable back to a
certified standard from the U.S. EPA or the National Institute
of Science and Technology (HIST).
b. A blind standard or a blind calibration solution must be
included in each group of about twenty samples.
-------
c. At least one of the following must be included in each group
of about twenty samples: '•
1. A matrix spike (spiked saaple; the method of known
additions).
-2. A CRN, if one is available in a matrix that closely
- approximates that of the samples. .Values obtained for the
CRN must be within the published values.
The concentrations in blind standards and solutions, spikes, and
CRMs vast met be more than 5 times the median concentration
expected to be present in the samples.
Assessing precision
a. A sampling replicate must be included with each set of samples
collected at each sampling location.
b. If the volume of the sample is large enough, replicate
analysis of at least one sample must be performed along with
each group of about ten samples.
Special eonsi.derafei.ons eoncemi.no the dissolved Measurement
Whereas the total recoverable measurement is especially subject
to contamination during the digestion step, the dissolved
measurement is subject to both loss and contamination during the
filtration step.
a. Filtrations must be performed using acid-cleaned plastic
filter holders and acid-cleaned membrane filters. Samples
must not be filtered through glass fiber filters, even if the
filters have been cleaned with acid. If positive-pressure
filtration is used, the air. or gas must be passed through a
0.2-um in-line filter; if vacuum filtration is used, it must
be performed on a class-100 bench.
b. Plastic filter holders must be rinsed and/or dipped between
filtrations, but they do not have to be soaked between
filtrations if all the samples contain about the same
concentrations of metal. It is best to filter samples from
lowr^fc high concentrations. A membrane filter must met be
used for more than one filtration. After each filtration, the
membrane filter must be removed and discarded, and the filter
holder must be either rinsed with metal-free water or dilute
acid and dipped in a metal-free acid bath or rinsed at least
twice with metal-free dilute acid; finally, the filter holder
must be rinsed at least twice with metal-free water.
c. For each sample to be filtered, the filter holder and membrane
filter must be conditioned with the sample, i.e., an initial
portion of the sample must be filtered and discarded.
The accuracy and precision of the dissolved measurement should be
-------
assessed periodically. A large volume of a buffered solution
(such as aerated 0.05 N sodium bicarbonate) should be spiked so
that th« concentration of the metal of'interest is in the range
of the lov concentrations that are to be measured. The total
recoverable concentration and the dissolved concentration of the
aetal in the spiked buffered solution should be measured
alternately until each measurement has been performed at least
ten times. The means and standard deviations for the two
measurements should be the same. All values deleted as outliers
must be acknowledged.
Raporti.no reaulta
To indicate the quality of. the data, reportsof results of
measurements of the concentrations of metals mast include a
description of the blanks, spikes, CRMs, replicates, and
standards that were run, the number run, and the results
obtained. All values deleted as outliers must be acknowledged.
Additional information
The items presented above are some of the important aspects of
"clean techniques"; some aspects of quality assurance and quality
control are also presented. This is not a definitive treatment
of these topics; additional information that might be useful is
available in such publications as Patterson and Settle (1976),
Zief and Mitchell (1976), Bruland et al. (1979), Moody and Beary
(1982), Moody (1982), Bruland (1983), Adeloju and Bond (1985),
Herman and Yeats (1985), Byrd and Andreae (1986), Taylor (1987),
Sakamoto-Arnold (1987), Tramontane et al. (1987), Puls and
Barcelona (1989), Windom et al. (1991), U.S. EPA (1992), Horowitz
et al. (1992), and Mriagu et al. (1993).
References
Adelo}«; S.B., and A.M. Bond. 1985. Influence of Laboratory
Environment on the Precision and Accuracy of Trace Element *
Analysis. Anal. Chem. 57:1728-1733.
Barman, S.S.t and P.A. Yeats. 1985. Sampling of Seawater for
Trace Metals. CRC Reviews in Analytical Chemistry 16:1-14.
Bruland, K.w., R.P. Franks, G.A. Knauer, and J.H. Martin. 1979.
Sampling and Analytical Methods for the Determination of Copper,
Cadmium, Zinc, and Nickel at the Nanogram per Liter Level in Sea
Water. Anal. Chin. Acta 105:233-245.
8
-------
Bruland, K.W. 1983. Trace Elements in Sea-water. In: Chemical
Oceanography, Vol. 8. J.P. Riley and R. Chester, •dm. Academic
Press, New York, NY. pp. 157-220.
Byrd, J.T., and M.o. Andreae. 1986. - Dissolved and Particulate
Tin in North Atlantic Seawater. Marine Chemistry 19:193-200.
Horowitz, A.J., K.A. Elrick, and M.R. Colberg. 1992. The Effect
of Membrane Filtration Artifacts on Dissolved Trace Element
Concentrations. Water Res. 26:753-763.
Moody, J.R. 1982. NBS Clean Laboratories for Trace Element
Analysis. Anal. Chen. 54:1358A-1376A.
Moody, J.R., and E.S. Beary. 1982. Purified Reagents for Trace
Metal Analysis. Talanta 29:ro03-101O.
Nriagu, J.O., G. Lawson, H.K.T. Hong, and J.M. Azcue. 1993. A
Protocol for Minimizing Contamination in the Analysis of Trace
Metals in Great Lakes Waters. J. Great Lakes Res. 19:175-182.
Patterson, C.C., and D.M. Settle. 1976. The Reduction in orders
of Magnitude Errors in Lead Analysis of Biological Materials and
Natural Waters by Evaluating and Controlling the Extent and
Sources of Industrial Lead Contamination Introduced during Sample
Collection and Processing. In: Accuracy in Trace Analysis:
Sampling, Sample Handling, Analysis. P.O. LaFleur, ed. National
Bureau of Standards Spec. Publ. 422, U.S. Government Printing
Office, Washington, DC.
Puls, R.W., and M.J. Barcelona. 1989. Ground Water Sampling for
Metals Analyses. EPA/540/4-89/001. National Technical
Information Service, Springfield, VA.
Sakamoto-Arnold, C.M., A.K. Hanson, Jr., D.L. Huizenga, and D.R.
Kester. 1987. Spatial and Temporal Variability of Cadmium in
Gulf Stream Warm-core Rings and Associated Waters. J. Mar. Res.
45:201-230.
Shiller, A.M., and E. Boyle. 1985. Dissolved Zinc in Rivers.
Nature,317:49-52.
Shiller, A.M., and E.A. Boyle. 1987. Variability of Dissolved
Trace Metals in the Mississippi River. Geochim. Cosmochim. Acta
51:3273-3277.
Taylor, J.K. 1987. Quality Assurance of Chemical Measurements.
Lewis Publishers, Chelsea, MI.
Tramontane, J.M., J.R. Scudlark, and T.M. Church. 1987. A
Method for the Collection, Handling, and Analysis of Trace Metals
in Precipitation. Environ. Sci. Techno1. 21:749-753.
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"Trefry, J.H., T.A. Nelsen, R.P. Trocine, s. Mate., and T.W.
Vetter. 1986. Rapp. P.-v. Reun. Cons. int. Explor. Mer.
186:277-288.
U.S. Environmental Protaction Agancy. 1983. Methods for
Chemical Analysis of Watar and Wastas. EPA-600/4-79-020.
National Tachnical Information Service, Springfield, VA.
Sactions 4.1.1, 4.1.3, and 4.1.4
U.S. Environmental Protaction Agancy. 1991. Methods for the
Determination of Metals in Environmental Samples. EPA-600/4-91-
010. National Technical Information Service, Springfield, VA.
U.S. Environmental Protaction Agency. 1992. Evaluation of
Trace-Metal Levels in Ambient Waters and Tributaries to New
York/New Jersey Harbor -for Waste Load-Allocation. Prepared by
Battalia Ocean Sciences under Contract No. 68-C8-0105.
Windom, H.L., J.T. Byrd, R.6. Smith, and F. Huan. 1991.
Inadequacy of NASQAN Data for Assessing Metals Trends in the
Nation's Rivers. Environ. Sci. Technol. 25:1137-1142. (Also see
Comment and Response, Vol. 25, p. 1940.)
Zief, M., and J.W. Mitchell. 1976. Contamination Control in
Trace Element Analysis. Chemical Analysis Series, Vol. 47.
Wiley, New York, NY.
10
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