vvEPA
United States
Environmental Protection
Agency
Off ice of Water
(WH-556F)
EPA 503/6-90-003
September 1990
The Green Bay Mass
Balance Project
An Advanced Analytical Model
For Environmental Management
GREAT LAKE^NATIONAL ESTpA^gROGTW^
The Green Bay System
Compartments and Fluxes of Contaminants
ry :.:.•.•
••;.Deposition .•;.•;.•;.•;.•;
Degradation
Products
Tributaries
Green Bay System
ummaiy
Green Bay Mass Balance Study is a pilot project to
.evaluate the feasibility of mass balance modeling for
toxic substances as a basic planning and management
^tool in restoring Great Lakes Water Quality. If proven, the
Irnethodologies employed in the Green Bay Model offer
^n accurate process for pollution control and remedial
action plans. Engineers and policy makers will be able to
temploy lake- and basin-wide simulations to test the costs
m
and benefits of alternative policies with greater confi-
dence than any current process.
The Green Bay Mas's Balance Study will be of most
interest to National Esl:uary Program participants in-
volved in scientific applications, to the Technical Advi-
sory Committees, and to those managers and staff who
are designing long-term monitoring strategies.
j
Printed on Recycled Paper
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Introduction
Since the first Great Lakes Water Quality Agreement was
signed in 1978, the Great Lakes National Program Office
has worked to restore proper functioning of the Great
Lakes ecosystem. While early work focused almost
exclusively on reducing eutrophication by controlling
nutrient inputs, more recent efforts have expanded to try
to understand and control inputs of toxic contaminants.
Techniques used early in the program that resulted in
effective nutrient control methods may, with modification,
be useful in managing toxic contamination.
When scientists began to focus on the major causes
of eutrophication in the 1960s, they constructed basic
input-output models of the Great Lakes to determine the
most immediate (and cost-effective) measures to ad-
dress the problem. Those analyses highlighted the need
to control phosphorus discharges to the Lakes. Re-
sulting control actions included banning phosphorus-
based detergents, modifying industrial and municipal
sewage treatment plant operations, and improving soil
conservation practices by farmers in the watershed, all of
which reduced phosphorus discharges. Such controls
have already resulted in marked improvements in the
Great Lakes' ecological health, especially in Lake Erie.
Signs of improvement include, for example, revitalized
fish communities.
Further studies have shown that a similar input-
output methodology may be applicable to toxic pollut-
ants, although the analytical and modelling processes
are more complex. When studying pollution control
technologies, a model — or series of models — would
accountforthe flows of the most important toxics through
the Great Lakes, from when they enter the lakes to when
they leave. This input-output scheme, based on the
principle of conservation of mass, is referred to as Mass
Balance Modelling.
Scientists and policy-makers hope to use the tech-
nique to evaluate alternative strategies for controlling
toxic contamination in the Great Lakes. This fact sheet,
prepared by EPA's Office of Marine and Estuarine Pro-
tection and the Great Lakes National Program Office,
describes the Green Bay Mass Balance study. Other fact
sheets in this series address the overall management
framework for the Great Lakes Water Quality Agree-
ment, and the multi-state (and international) fish moni-
toring program for measuring the presence of toxic
chemicals in commercial and recreational fish species.
An earlier fact sheet covers the Great Lakes National
Program Office load management strategy for phospho-
rus.
Study Objectives
The Green Bay Mass Balance Study was begun to test
the feasibility of using a mass balance approach to
assess the sources and effects of toxic pollutants which
are spreading throughout the Great Lakes food chain.
Specific objectives include:
• Assessing the technical and economic feasibility of
the Mass Balance approach for use in the manage-
ment of pollutant loading and impacts on Great
Lakes ecosystems;
• Calibrating the Mass Balance model for sources,
transport routes and fates of pollutants in the Great
Lakes ecosystems in general;
• Identifying the major sources of pollutants entering
the Green Bay ecosystem and ranking their relative
significance; and
• Demonstrating methods and priorities for further
studies of toxic pollutants in the Great Lakes.
Four chemicals and chemical groups representative
of major classes of toxic compounds were selected for
the Mass Balance Study. They are: PCBs (and related
compounds), dieldrin (a pesticide), cadmium, and lead.
By including the entire family of PCB chemicals, the
study will actually measure 209 chemicals, over 80 of
which are currently found in detectable quantities.
Inputs of these chemicals have been measured in all
of the major surface water tributaries flowing into Green
I
Modeling
PHHf
Management
Committee
Technical
Coordinating
Committee
I
Field and
Technical
Operations
I
I I
Field and
Biota Analytical
Methods
Bay, in point sources, in wet and dry precipitation and in
groundwater. The goal of the Green Bay Mass Balance
Study is to predict the concentrations of these four
chemicals in walleye pike, brown trout, and carp (the
defined end points of the study's food chain) to an
acceptable level of accuracy, at an affordable cost. Once
a mass balance budget has been established for each
pollutant of concern, it should be possible to simulate the
long-term effects on Great Lakes water quality by
mathematical modeling.
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The basic mass balance model can be reduced to the following formula:
Input + Generation - Accumulation - Consumption = Output
Produced
within
system
Enters
through
system
boundaries
Stored
within
system
Transformed or
degraded
within system
Exits
to
outside
To meet the study goal for accurate prediction of toxic
pollutants in the fish at the end of the food chain, study
planners estimate that data collection and analysis
procedures must be accurate to within ±20% of actual
mean values for major sources and "compartments" of
pollutants. In the world of ecological research, these
are very stringent requirements.
The study began in 1986, with preliminary monitor-
ing and planning, and is scheduled to be completed in
1991. The bulk of the data sampling was performed
during 1989 and 1990.
The Study's annual funding in Fiscal Years 1989
and 1990, provided by GLNPO, was $1.1 million, with
minor additional contributions from the other participat-
ing agencies.
Lessons Learned
If successful, the Green Bay Mass Balance Study can
provide the International Joint Commission with a new
range of scientifically validated analysis and planning
tools for managing pollutant loads throughout the Great
Lakes. While the scope and cost of the Green Bay Study
are beyond the means of other areas just getting involved
in the National Estuary Program, there are important
lessons to be learned from the Green Bay Mass Balance
Study:
• There are major advantages to be gained from
organizing a method for coordinating a variety of
individual scientific projects (most of which will be
carried out by academic interests, whether there is
an estuary program or not). By working with local
academic, scientific, and environmental consulting
groups to identify major ecosystem issues in the
estuary, by defining basic data standards for all
interested researchers, and by establishing a com-
mon database, accessible to all interested re-
searchers, a Management Conference can encour-
age the development of a considerable body of
scientific and technical information with long-term
potential utility for policy research and estuary man-
agement.
There are a variety of new environmental manage-
ment tools like the Green Bay Mass Balance Model
which are being developed and assessed. Technical
Advisory Committees need to monitorthese projects
to identify those new technologies that could make
contributions to the local management program on
two different levels:
— the discovery of important new estuary manage-
ment "facts" that need to be incorporated in
planning and management strategies (e.g., hy-
drilla promotes the rapid restoration of many
estuarine areas1,); or
— new models or simulations that can be adapted
at low cost to the management needs of the local
estuary.
For further information fen the Green Bay Mass Balance
Study, contact the Great Lakes National Program Office
(312/353-3503) or the 'Office of Marine and Estuarine
Protection, Technical Sijpport Division (202/475-7102).
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