PB84-157155
MEXAMS (Metals Exposure
Analysis Modeling System)
Battelle Pacific Northwest Labs., Richland, WA
Prepared for
Environmental Research Lab., Athens, GA
Feb 84
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing]
REPORT NO.
EPA-600/3-84-031
3. RECIPIENT'S ACCESSIQf*^Q. _ _
'
TITLE AND SUBTITLE
MEXAMS—The Metals Exposure Analysis Modeling
System
5. REPORT DATE
February 1984
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPOI
A.R. Felmy, S.M. Brown, Y. Onishi, S.B. Yabusaki,
anH K.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle
Pacific Northwest Laboratories
Richland, WA 99352
10. PROGRAM ELEMENT NO.
CCUL1A
11. CONTRACT/GRANT NO.
68-03-3089
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency—Athens GA
Office of Research and Development
Environmental' Research Laboratory
Athens, GA 30613
13. TYPE OF REPORT AND PERIOD COVERED
Final, 9/81-8/83
14. SPONSORING AGENCY CODE
EPA/600/01
15. SUPPLEMENTARY NOTES
16. ABSTRACT
MEXAMS, the Metals Exposure Analysis Modeling System, provides an enhanced
capability for assessing the impact of priority pollutant metals on aquatic systems.
It allows the user to consider the complex chemistry affecting the behavior of metals
in conjunction with the transport processes that affect their migration and fate.
This is accomplished by linking MINTEQ, a geochemical model, with EXAMS, an aquatic
exposure assessment model. MINTEQ is a thermodynamic equilibrium model that computes
aqueous speciation, adsorption and precipitation/dissolution of solid phases. It has
a well-documented thermodynamic data base that contains equilibrium constants and
other accessory data for seven priority pollutant metals: arsenic, cadmium, copper,
lead, nickel, silver and zinc. The model was developed by combining the best feature
of two other existing geochemical models MINEQL and WATEQ3. EXAMS is designed for th
rapid evaluation of .synthetic organic pollutants. Given the characteristics of a
pollutant and an aquatic system, EXAMS computes steady-state pollutant concentrations
(exposure), the distribution of the pollutant in the system (fate), and the time re-
quired for effective purification of the-system (persistence). Its linkage to MINTEQ
required several modifications. To facilitate the use of MEXAMS, a user interactive
program was developed. This program queries the user to obtain water quality data
for MINTEQ, then controls the operation of MINTEQ and EXAMS, passing simulation re-
sults back and forth between the models.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
185"
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
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DISCLAIMER
The information in this document has been funded wholly or in part
by the United States Environmental Protection Agency under Contract No.
68-03-3089 to Battelle, Pacific Northwest Laboratories. It has been
subject to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade names or
commercial products does not constitute endorsement or recommendation
for use.
The MEXAMS computer code has been tested against other computer
programs to verify its computational accuracy. Nevertheless, errors in
'the code are possible. The U.S. Environmental Protection Agency assumes
no liability for either misuse of the model or for errors in the code.
The user should perform verification checks of the code before using
it.
ii
Reproduced from
best available copy.
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FOREWORD
As environmental controls become more costly to implement and the
penalties of judgment errors become more severe, environmental quality
management requires more efficient analytical tools based on greater
knowledge of the environmental phenomena to be managed. As part of
this Laboratory's research on the occurrence, movement, transformation,
impact, and control of environmental contaminants, the Technology
Development and Applications Branch develops management or engineering
tools to help pollution control officials achieve water quality goals.
Concern about environmental exposure to heavy metals has increased
the need for techniques to predict the behavior of metals entering
natural waters as a result of the manufacture, use, and disposal of
commercial products. A number of mathematical models have been developed
to provide data on metals transport and fate from which exposure assess-
ments can be made. The modeling technique described in this manual permits
the user to examine speciation of heavy metals along with transport and
fate in various aquatic systems. Because different species of a metal
cause different biological effects, this model should help users better
relate metals discharges to observed effects.
William T. Donaldson
Acting Director
Environmental Research Laboratory
Athens, Georgia
iii
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ABSTRACT
MEXAMS, the Metals Exposure Analysis Modeling System, provides an
enhanced capability for assessing the impact of priority pollutant metals
on aquatic systems. It allows the user to consider the complex chemistry
affecting the behavior of metals in conjunction with the transport processes
that affect their migration and fate. This is accomplished by linking
MINTEQ, a geochemical model, with EXAMS, an aquatic exposure assessment
model.
MINTEQ is a thermodynamic equilibrium model that computes aqueous
speciation, adsorption and precipitation/dissolution of solid phases. It
has a well-documented thermodynamic data base that contains equilibrium
constants and other accessory data for seven priority pollutant metals:
arsenic, cadmium, copper, lead, nickel, silver and zinc. The model was
developed by combining the best features of two other existing geochemical
models: MLNEQL and WATEQ3.
EXAMS is designed for the rapid evaluation of synthetic organic
pollutants. Given the characteristics of a pollutant and an aquatic system,
EXAMS computes steady-state pollutant concentrations (exposure), the
distribution of the pollutant in the system (fate), and the time required
for effective purification of the system (persistence). Its linkage to
MINTEQ required several modifications.
To facilitate the use of MEXAMS, a user interactive program was
developed. This program queries the user to obtain water quality data
IV
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for MINTEQ, then controls the operation of MINTEQ and EXAMS, passing
simulation results back-and-forth between the models.
As it is currently structured, MEXAMS can be used in a number of ways.
It can be used like EXAMS to perform rapid hazard evaluations for priority
pollutant metals. MEXAMS can also be used to evaluate the impact of point
source discharges and mine drainage as well as to support the interpretation
of metals bioassay data. Finally, and perhaps most importantly, MEXAMS can
be used as a framework for defining what is and what is not known about the
behavior of priority pollutant metals in aquatic systems. This framework
will make it possible to identify the need for and guide the performance of
future research.
This report was submitted in fulfillment of Contract No. 68-03-3089 by
Battelle, Pacific, Northweat Laboratories under the sponsorship of the U.S.
Environmental Protection Agency. The report covers the period September
14, 1981 to August 31, 1983, and work was completed as of August 31, 1983.
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CONTENTS
Foreword
Abstract. iv
Figures • viii
Tables ««« ix
1. Introduction. 1
2. Conclusions. 6
3. Recommendations. 8
4. Description of MEXAMS. 10
MEXAMS Components. 10
Operation of MEXAMS 16
Applicability. 20
Limitations. 22
5. A Primer on Key Concepts in Aqueous Chemistry..... 25
Aqueous Speciation. 25
Act ivity 29
Adsorption 30
Solid Phase Reactions 31
6. Guidelines for Use _ 34
Use of EXAMS 34
MINTEQ Tutorial 39
Use of MINTEQ 42
Data Input to MEXAMS Using MISP. 63
vi
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7. Programmers Supplement 104
System Overview 104
MEXAMS Structure 105
Description of MEXAMS Routines 109
EXAMS Code MODIFICATIONS 125
MINTEQ Implementation Test Cases 139
MEXAMS Implementation Test Case. 142
MEXAMS Resource Requirements. 143
References 146
Appendices
A. MINTEQ Program Listing 150
-B. TEST CASE RESULTS 151
C. DESCRIPTION OF THE MINTEQ INPUT FILE 152
D. MISP PROGRAM LISTING 165
E. EXAMPLE MISP RUNS. 166
VI1
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FIGURES
Number
1 Schematic showing overall structure of MEXAMS 11
2 Detailed block diagram for MINTEQ 106
3 Detailed block diagram for the batch version of EXAMS... 107
4 Detailed block diagram for MISP 108
5 Detailed block diagram for the batch version of EXAMS showing
the subroutines that were modified 126
6 Visualization of data storage structure 137
VLll
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TABLES
Number Page
1 Dissolved Species of Lead 26
2 Aqueous Species of Iron 28
3 Components in MINTEQ 44
4 Aqueous Complexes 45
5 Mineral Group I. D. Numbers 47
6 Solid Phases and I.D. Numbers 48
7 Recommended List of Type V Solids 58
8 Gas Phases in MINTEQ 79
9 Definition of Terms Used in the MINTEQ Output 84
10 Section One of the MINTEQ Output 86
11 Section Two of the MINTEQ Output 87
12 Section Three of the MINTEQ Output 88
13 Section Four of the MINTEQ Output 89
14 Section Five of the MINTEQ Output (Output Data) 90
15 Section Five of the MINTEQ Output (Percentage
Distribution of Components) 92
16 Section Five of the MINTEQ Output (Saturation Indices
for All Minerals and Solids) 97
18 Description of Important Variables and Arrays Used
in MINTEQ 112
19 Noncarbonate Alkalinity Species 136
20 A Comparison of Selected MINTEQ Trace Metal Speciation
with the Results of Several Geochemical Models 141
IX
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TABLES (Continued)
Page
Sample EXAMS Input Data 144
22 Concentrations of Major Cations and Anions for the
MEXAMS Implementation Test Case 145
C-l Highest I.D. Numbers of Aqueous Complexes 338
C-2 Highest I.D. Numbers of Minerals and Solids 339
C-3 MINTEQ Input Data for the Seawater Test Case 340
C-4 MINTEQ Input Data for the River Water Test Case 341
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SECTION 1
INTRODUCTION
As a result of the National Resources Defense Council (NRDC)/Environ-
mental Protection Agency Settlement Agreement (as modified), the EPA is
required to examine the need for more stringent effluent limitations and
guidelines in order to attain and maintain acceptable water quality
conditions. EPA must also examine the presence, sources, effects of, and
interrelationships between priority pollutants in aquatic systems.
Given the Water Quality Criteria published on November 18, 1980 in the
Federal Register, the one class of priority pollutants likely to receive
considerable attention is the priority pollutant metals. One reason for
this attention is the fact that the current criteria are based on "total
recoverable" rather than "dissolved" concentrations. Historically, only
total concentrations were reported in the published results of aquatic
bioassays for metals, even though it was generally known and accepted that
the dissolved fraction is the most bioavailable and toxic, and that certain
dissolved species are much more toxic than others. Only recently have
investigators like Andrew et al. (1977), Chakoumakos et al. (1979) and Allen
et al. (1980) sought to experimentally determine the toxicity of different
dissolved species.
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Another reason for the growing attention is the concern that the cri-
teria are too stringent. Industry would prefer that either the dissolved
fraction or the most toxic forms be regulated so they can avoid unnecessary
treatment. They and others point to the many locations where total metal
concentrations exceed the criteria without any apparent ecological impacts.
The final reason is that EPA is now giving states the latitude to
establish the specific standards. This move is in recognition of the major
impact that local water quality conditions can have on the proportion of
total metal that is dissolved and on the species that are likely to be
present.
These issues have generated a need to reexamine the basis for the
priority pollutant metal criteria. They have also generated a need to
develop improved methods for predicting how metals will behave in aquatic
systems.
To date,, virtually all modeling studies directed at examining the
migration and fate of metals have neglected many of the more important
chemical interactions controlling their behavior in aquatic systems. In
their study of Pb, Cd, Zn, Cu and S movement through Crooked Creek Watershed
in Missouri, Munro et al. (1976) considered only metal adsorption through
the use of an equilibrium partitioning coefficient. A similar approach was
used by Raridon et al. (1976) in the study of Cd and K movement in Walker
Branch Watershed in Tennessese and by De Pinto(a) et al. in their analysis
(a) Presentation by J. V. DePinto, W. L. Richardson, and R. Wethington on
Mathematical Modeling of Heavy Metals Transport in the Flint River,
Michigan at the SETAC Third Annual Meeting in Arlington, Virginia on
November 14-17, 1982.
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of Zn, Cd and Cu movement in the Flint River in Michigan. Orlob et al.
(1980) used a non-equilibrium partitioning coefficient for sediment
adsorption, as well as one for dissolved organic matter, in their study of
Cu movement off of the California coast.
None of these studies, however, explicitly considered metal speciation
and its resultant effect on metal adsorption and precipitation, both of
which act to reduce the amount of metal in solution.
These factors are explicitly considered in MEXAMS, the Metals Exposure
Analysis Modeling System. It represents an improvement in metals modeling
in that the complex chemistry affecting the behavior of a metal and the
transport processes affecting its migration and fate are handled by two
separate, but linked, models. The chemical interactions are handled by
MINTEQ, a geochemical model that uses fundamental thermodynamic equilibrium
relationships and data to calculate dissolved, adsorbed and precipitated
metal concentrations. The migration and fate of the metal is handled by the
Exposure Analysis Modeling System (EXAMS), a. steady-state transport model
developed primarily as a screening level model by the EPA Environmental
Research Laboratory in Athens, Georgia.' '
A similar approach was also recently taken Dr. Bernard Chapman at the
Commonwealth Scientific and Industrial Research Organization (CSIRO) in
Australia. Dr. Chapman linked MINEQL with his own transport model to
(b) Burns, L. A., D. M. Cline and R. R. Lassiter. Exposure Analysis Modeling
System (EXAMS): User Manual and System Documentation. U.S. Environmental
Protection Agency, Athens, Georgia. EPA-600/3-82-023.
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examine the impacts of mine drainage on the quality of receiving waters
(Chapman et al. 1982 and Chapman 1982). The success of his modeling studies
provides considerable support to the approach taken in the development of
MEXAMS.
This report is a user's manual for MEXAMS. It is divided into four
main sections. The first provides a general description of MEXAMS.
Specifically, the function of each component of MEXAMS is described, as is
the operation of the system. This section concludes with a discussion of
the applicability and limitations of the modeling system.
The second section is a primer on key concepts in aqueous chemistry.
In preparing this report it was assumed that most users would not have
formal training in chemistry. For this reason, an introduction to some of
the concepts important to understanding the chemistry of metals in natural
waters is provided.
The third section discusses how to use MEXAMS. Specifically, it
discusses the options available to the user, data requirements and how to
interpret model outputs and error messages. To facilitate the use of
MEXAMS, a step-by-step discussion of data entry procedures is provided.
The fourth section is a programmer's supplement. It outlines: 1) the
structure of MEXAMS, 2) resource requirements for its operation, and
3) procedures for its implementation.
Before applying MEXAMS, the reader is encouraged to review MINTEQ - A
Computer Program for Calculating Aqueous Geochemical Equilibria by.
A. R. Felmy, D. C. Girvin, and E. A. Jenne, (1983). This report presents
the mathematical and chemical concepts embodied in MINTEQ. While it is not
necessary to master these concepts in order to use MEXAMS, it is important
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that the user be familiar with the basic theory behind MINTEQ. The reader
is also encouraged to review Exposure Analysis Modeling System (EXAMS):
User Manual and System Documentation by L. A. Burns, D. M. Cline, and
R. R. Lassiter. While not all of the capabilities of the EXAMS model are
used in MEXAMS,' the user should be familiar with the calculations made by
the model and its data requirements.
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SECTION 2
CONCLUSIONS
MINTEQ, a thermodynamic equilibrium geochemical model, has been linked
with EXAMS, a steady-state aquatic exposure assessment model, to produce
MEXAMS, the Metals Exposure Analysis Modeling System. As a result, much of
the complex chemistry affecting the behavior of selected priority pollutants
in aquatic systems can be explicitly considered. Specifically, chemical
speciation and its effect on the adsorption and precipitation of metals can
be considered. MEXAMS should, therefore, provide more accurate predictions
of the metal concentrations likely to be found in different aquatic
systems. It should also overcome some of the limitations inherent in
earlier attempts to model the behavior of metals.
MEXAMS is applicable to a fairly broad range of problems associated
with the impacts of priority pollutant metals on aquatic systems. It can be
used to perform both screening level and site specific analyses of different
sources of metals such as industrial discharges and mine drainage. It can
also be used to support the interpretation of data collected during aquatic
bioassays and as a framework for guiding future research.
The modeling system contains an interactive program that helps the user
prepare water quality data for input to MINTEQ. It also queries the user to
obtain user run information which is then used to control the operation of
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MINTEQ and EXAMS and the transfer of simulation results back-and-forth
between the models. Thus, the effort required to use the system is
mi nimi zed.
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SECTION 3
RECOMMENDATIONS
The Metals Exposure Analysis Modeling System, MEXAMS, should be applied
to a series of aquatic systems to: 1) demonstrate the importance of explic-
itly considering the effects of precipitation, adsorption and aqueous spe-
ciation when assessing the behavior of metals in aquatic systems, and
2) identify any limitations that could impact the applicability of the
modeling system. Initial applications should be made to hypothetical, but
representative, aquatic systems to identify important processes and critical
data needs. This should be followed by applications to one or more site
specific problems.
Available thermodynamic data for antimony, berylium, chromium, mercury,
selenium and thallium should be reviewed for entry into the MINTEQ thermody-
namic data base. Clearly, this effort should take advantage of the review
work that has already been performed by other geochemical modelers. This
would broaden the applicability of MEXAMS to all of the priority pollutant
metals contained in the EPA/NRDC Settlement Agreement (as modified).
The literature should be reviewed to obtain available thermodynamic
equilibrium constants and other accessary data for the formation of organic
complexes. This effort would overcome one of the major limitations of the
modeling system.
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Attention should be given to the development of efficient techniques
for coupling geochemical models with more complex aquatic transport models.
This would provide the capability to conduct detailed, site-specific waste-
load allocation studies, particularly for those aquatic systems where water
quality variations and/or the movement of water and sediments are highly
dynamic.
In conjuction with the development of such techniques, research
should be initiated to develop approaches for handling the kinetics of pre-
cipitation/dissolution, adsorption/desorption and oxidation/reduction. In
the first two cases, this research should largely focus on the review of
existing data and experimental work directed at filling critical data gaps.
In the latter area, research should be focussed on developing both a better
understanding of oxidation/reduction mechanisms and appropriate algorithms
for inclusion in geochemical models.
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SECTION 4
DESCRIPTION OF MEXAMS
This section provides a brief introduction to MEXAMS. It overviews
each of the components in MEXAMS and the operation of the overall modeling
system. It also describes the types of analyses that can be performed with
MEXAMS and the limitations the user should be aware of before using the
system.
MEXAMS COMPONENTS
MEXAMS consists of three components: 1) a geochemical model, 2) an
aquatic exposure assessment model, and 3) a user interactive program. The
geochemical model simulates the complex chemical interactions that affect
metal behavior in natural waters. The exposure assessment model simulates
the transport processes affecting metal migration and fate in aquatic
systems. The user interactive program links the two models and aids in the
application of the overall system. Figure 1 shows how these three
components are linked. Each component is discussed in more detail below.
MINTEQ is the geochemical model in MEXAMS. It is a thermodynamic
equilibrium model that computes aqueous speciation, adsorption and
precipitation/dissolution of solids. Speciation is calculated using an
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USER INTERACTIVE
PROGRAM
(MISP)
WATER
CHEMISTRY
GEOCHEMICAL
MODEL
(MINTED.)
METAL
CONCENTRATIONS
METAL
CONCENTRATIONS
EXPOSURE
ASSESSMENT
MODEL
(EXAMS)
METAL SPECIATION METAL MIGRATION
AND FATE
Figure 1. Schematic showing overall structure of MEXAMS
-equilibrium constant approach wherein a series of mass action expressions
are solved subject to mass balance constraints on each chemical component.
A knowledge of how a metal will speciate is important for two reasons.
"•irst, in order to accurately predict how much metal will be taken out of
solution by precipitation and adsorption, the aqueous speciation must be
;:nown. Second, since the toxicity and bioavai labi 1 ity of individual species
can vary by several _orders of magnitude, a knowledge of metal speciation is
needed to make accurate estimates of aquatic impacts.
In MINTEQ, adsorption is treated as being analogous to aqueous specia-
tion. As c. result., mass action expressions can be formulated for adsorption
reactions. MINTEQ contains six algorithms for calculating adsorption. The
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first is a single valued partitioning coefficient or Kd that has been
corrected for the activity of the metal species binding to the surface. The
corrected -value is called an "activity Kd", and since it is independent of
the aqueous speciation, it may be applicable over a broader range of water
quality conditions than a standard Kd which is based on concentration. The
second algorithm is an "activity" Langmuir isotherm where the Langmuir
constants are formulated in terms of the activity of the metal species
binding to the surface. The third algorithm is an "activity" corrected
Freundlich isotherm where again the Freundlich equation is formulated in
terms of the activity of the metal species binding to the surface. (a) The
fourth algorithm is for simple ion exchange reactions where the activity
ratio of the exchanging species is assumed to remain constant. The constant
capacitance model and triple layer model are the other two options. They
are more theoretically based approaches that consider the electrostatic
potential at the surface of the sorbing media and the effect of pH and ionic
strength changes on surface properties.
MINTEQ can compute the mass of metal transferred into or out of solu-
tion as a result of the dissolution or precipitation of solid phases. While
this calculation is limited by the fact that it is made for equilibrium
conditions and precipitation/dissolution reactions may be kinetically con-
trolled, it is possible to obtain reasonable results if the solids con-
sidered by MINTEQ as possible equilibrium phases are properly selected.
That is, the user must permit MINTEQ to consider only those solids whose
formation is not limited by kinetic barriers.
(a) This option is not available on the PDF 11/70 version of MINTEQ.
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As with any geochemical model, MINTEQ requires two types of data:
1) thermodynamic data and 2) water quality data. The thermodynamic data are
equilibrium constants, enthalpies of reaction and other basic information
required to predict the formation of each species or solid phase. The water
quality data are the physical and chemical properties of the water body
being analyzed. The user only has to generate the water quality data in
order to use MINTEQ. The thermodynamic data are contained in a data base
that accompanies the model. This data base is constantly being updated and
expanded as new or improved data become available.
MINTEQ was developed by combining the best features of two other
existing geochemical models: MINEQL (Westall et al. 1976) and WATEQ3 (Ball
et al. 1981). MINTEQ uses MINEQL's computational structure. The WATEQ3
features added to the computational structure were the thermodynamic data
base and algorithms for correcting changes in water temperature and ionic
strength. The overall model is discussed in detail in MINTEQ - A Computer
Program for Calculating Aqueous Geochemical Equilibria by A. R. Pel my,
D. C. Girvin and E. A. Jenne (1983).
MINEQL was developed to solve a similar class of problems as earlier
computer programs such as REDEQL (Morel and Morgan, 1972) and REDEQL2
(McDuff and Morel, 1973) but with a mathematically more general
computational method. However, familiarity with the use of these earlier
programs will be beneficial when learning to use MINTEQ.
EXAMS, the Exposure Analysis Modeling System, developed by the EPA
Environmental Research Laboratory in Athens, Georgia, is the aquatic
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exposure assessment model in MEXAMS.(a) It is a steady-state model for
screening-level exposure assessments that is applicable to rivers and
lakes. The model was developed primarily for use with organic compounds,
and it provides estimates of exposure, persistence and fate. Operationally,
exposure is defined as the pollutant concentrations that would be achieved
under steady-state conditions. That is, the resultant concentrations when
loadings to the aquatic system are balanced by losses of pollutant from the
system as a result of transport and transformation processes. Persistence
is defined as the time required for pollutant concentrations to dissipate
assuming the pollutant loadings are terminated. Fate is defined as the
steady-state distribution of the pollutant within each compartment. The
Fate calculation gives the user an indication of the relative importance of
each transport and transformation process.
The processes considered by the original EXAMS can be divided into four
categories: 1) ionization and sorption, 2) transformation, 3) transport,
and 4) chemical loadings. For ionization and sorption, EXAMS can consider
up to 15 molecular species of a given pollutant. These include the
uncharged parent molecule and its singly- and doubly-charged cations and
anions. Each of these can occur in a dissolved, sediment-sorbed or
biosorbed form. Equilibrium sorption is calculated using equilibrium
distribution coefficients. The second category, transformation processes,
includes photolysis, hydrolysis, biolysis and oxidation. Rates of
(a) Burns, L. A., D. M. Cline and R. R. Lassiter. Exposure Analysis Modeling
System (EXAMS): User Hanual and System Documentation. U.S. Environmental
Protection Agency, Athens, Georgia. EPA-600/3-82-023.
14
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transformation for each process can be assigned to each of the 15 molecular
species. The third category, transport processes, includes the movement of
dissolved, sediment-sorbed, and biosorbed fractions and volatilization.
Since EXAMS does not explicitly compute water and sediment movement, they
must be obtained from field measurements or other models. Volatilization is
calculated using the two-resistance or "two-film" model. The final
category, chemical loadings, includes external pollutant loadings from point
sources, non-point sources, dry fallout or aerial drift, atmospheric wash-
out and ground-water seepage. The user's manual and system documentation
report for EXAMS provides extended discussions of how each of the above
processes are modeled.
The coupling of EXAMS with MINTEQ required several modifications to the
code and the way it is used. Code modifications were designed in such a way
that all of the original EXAMS options and capabilities were retained, and
no additional input data would be required. Most of the modifications
related to by-passing unnecessary calculations or calculations either not
applicable to metals or duplicated by MINTEQ. For instance, there is no
need for EXAMS to compute adsorption since MINTEQ will provide the quantity
of metal sorbed to sediments and biota. Modifications of this type were
handled largely without changing the code. Another example is chemical
degradation which is applicable to organics but not to metals. Through the
proper specification of EXAMS inputs, most of these calculations can be
by-passed. This means that the user does not have to maintain two different
versions of EXAMS, one for organics and one for metals. The other
modifications related to the expansion of the EXAMS algorithms to consider
the precipitated fraction of the metal. This involved modifying the
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transport algorithm. It also involved adding a scheme to by-pass the
solubility limitation of 50% of the aqueous solubility or 1 x 10~5 M for the
neutral species if the model is being used for metals. Section 6 of this
report contains a detailed discussion of the specific modifications made to
EXAMS.
MISP, the MEXAMS Interactive Software Program, is the third component
in MEXAMS. It has several important functions. First, it helps the user
input data to MINTEQ. Input data for EXAMS are not handled by MISP; they
must be prepared using the procedure outlined .in the EXAMS User's Manual.
However, the program does access the EXAMS input file once it has been
prepared. MISP also queries the user to obtain more specific information on
whether MINTEQ will be used alone or in combination with EXAMS, and the
types of output information the user would like. Finally, and most
importantly, MISP links MINTEQ with EXAMS and controls the operation of each
model. This linkage consists of a series of event flags that are passed
back and forth between the models that tell EXAMS or MINTEQ when to start or
stop execution and which data files to access.
OPERATION OF MEXAMS
MEXAMS can be operated in three modes: 1) the MINTEQ-only mode, 2) the
EXAMS-only mode, and 3) the coupled MINTEQ and EXAMS mode. The MINTEQ only
mode allows the user to analyze how changes in water chemistry will affect
the behavior of a metal without regard for the effect of transport pro-
cesses. The EXAMS only mode functions exactly like the original EXAMS
model. The coupled MINTEQ and EXAMS mode allows the user to also consider
the effect of transport processes and chemical interactions.
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The operation of MEXAMS in the MINTEQ-only mode is very straight-
forward. The user simply enters MISP and- selects this mode. If a MINTEQ
input file is not already available, the user is queried for information on
the physical and chemical characteristics of the water being analyzed. This
information is used to construct an input data file for MINTEQ. The user
can create any number of files using this procedure. Once they are created,
the user can initiate MINTEQ and wait for the results. MINTEQ input files
can only be created in the MINTEQ-only mode.
The EXAMS-only mode only requires an EXAMS input file. MISP will copy
this file to the EXAMS input file FOR005.DAT.
In the coupled mode the operation is more complex. Before entering
MISP, the user must create an EXAMS input file that describes the char-
acteristics of the aquatic system and metal loadings being assessed. This
is not a difficult process. It involves following the instructions given in
Section 6 of this report and the EXAMS user's manual. The user then enters
MISP and selects the coupled mode. This procedure is the same as that for
the MINTEQ only mode, MISP will query the user for a MINTEQ input file for
each EXAMS compartment or set of compartments with different water quality
characteristics. The MINTEQ input files can be created by previous runs of
MISP in the MINTEQ only mode or by following the precedure outlined in
Appendix C for preparing MINTEQ input files. The user will be queried to
provide some run-specific information that controls the number of times
metal concentrations are updated by MINTEQ. MEXAMS is now ready to simulate
metal behavior, migration and fate.
The first step in the calculation is for EXAMS to make an initial
exposure calculation assuming no adsorption or precipitation. This calcu-
17
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lation provides an initial distribution of dissolved metal concentrations in
each compartment of the aquatic system. These concentrations, along with
the suspended sediment and biota concentrations for each compartment, are
then transferred to MISP. MISP passes the dissolved metal concentration in
the first compartment to MINTEQ along with a flag telling MINTEQ to read the
water quality data for that compartment. MINTE.Q uses these data to obtain
an improved estimate of the concentrations of metal in solution, adsorbed to
sediments, adsorbed to biota and in a precipitated form for the compart-
ment. These results are passed back to MISP where they are summed and
divided by the total to obtain metal fractions (e..g., the fraction of the
metal in solution, adsorbed or precipitated). MISP then proceeds to the
second compartment. If the water quality conditions of this compartment are
identical to the first and the total metal concentrations are approximately
the same (within 5% of each other), then MISP simply uses the same fractions
calculated for the first compartment and MINTEQ is not called. If the total
metal concentrations differ by more than 5%, another MINTEQ calculation is
performed. This calculation is faster because MINTEQ has already read the
water quality data and has stored the results of the previous calculation.
An entire new calculation is made only when MISP encounters a compartment
with completely different water quality conditions.
Once all of the metal fractions have been computed, MISP passes them
back to EXAMS for insertion in its ALPHA array. This array is used through-
out EXAMS to compute pollutant transformation and transport. At this point,
EXAMS again predicts exposure levels (i.e., new dissolved, adsorbed and pre-
cipitated metal concentrations in each compartment). The option now exists
for EXAMS to iterate again with MINTEQ or proceed to calculate fate and
18
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persistence. This decision depends on the number of iterations specified by
the user before initiating the simulation.
Upon completion of the exposure calculation, EXAMS sums the flux rate
of pollutant attributable to each transport and transformation process over
the entire aquatic system, and then computes the significance of each
process by dividing each flux rate by the total of the external loadings.
This gives a percentage for each flux rate that is reported as an analysis
of metal fate.
The persistence calculation in EXAMS i'nvolves terminating the chemical
loadings and computing the dissipation of the chemical over approximately
two system-level halflives. To limit the number of computations, the
estimated time frame required to achieve two halflives is divided into
12 equal increments of time. Since metal concentrations in each compartment
will probably change throughout the persistence calculation, periodic
updates of the metal fractions in the ALPHA matrix may be required.
Therefore, the user is given the option to have the metal fractions updated
after every persistence calculation, every other calculation, every third
calculation, every fourth calculation, every fifth calculation or not at
all. The number of times is specified by the user before initiating the
simulat ion.
Outputs from EXAMS, MINTEQ, and MISP are provided after the completion
of the persistence calculation. The EXAMS outputs give exposure, fate and
persistence predictions. The MINTEQ outputs give details on the chemical
interactions occurring in each compartment. The MISP output gives a brief
summary of the EXAMS-MINTEQ interactions. The EXAMS,MINTEQ and MISP outputs
are in files FOR002.DAT, MINTEQ.OUT and MISP.OUT, respectively.
19
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APPLICABILITY
MEXAMS, as it was originally conceived, was developed to provide EPA
with a predictive tool capable of performing screening level analyses. The
user can create a series of MINTEQ input files describing a broad range of
water quality conditions in order to evaluate how a specific priority pollu-
tant metal will speciate, adsorb or precipitate. Using the many generalized
environments that have been created for EXAMS, or any other type of general
aquatic environment, the user can also rapidly evaluate exposure, fate and
persistence. This type of application would give the user some indication
of which processes are of importance in different types of aquatic systems
and which types of systems are most likely to be impacted by metals.
MEXAMS can also be used on a more site-specific basis to investigate
the potential impacts of different metal sources like industrial discharges
or mine drainage. Such applications can include the use of MINTEQ alone or
in conjunction with EXAMS. An example of the former is a study by Morel
et al. (1975) on the fate of trace metals discharged from a Los Angeles
County treatment plant. They used a geochemical model to show how the
oxidation and dilution of sewage by seawater would affect the fate of
different metals. An example of the latter are the recently published
studies by Chapman et al. (1982) and Chapman (1982) on the impacts of mine
drainage on the quality of a creek in Australia.
Another application of MEXAMS relates to improving the information
available from bioassays. Historically, only the "total" concentration of
metal present was measured during the performance of aquatic bioassays.
This is largely the reason the current Federal criteria are based on "total
20
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recoverable" levels. If the chemistry of the dilution waters were known,
MEXAMS, more specifically MINTEQ, could be used to estimate the dissolved
concentration of metal present during the bioassay, as well as the species
that were present. The former would provide a means of adjusting the
current standards to a dissolved metal basis. This would provide more
reasonable standards since the dissolved fraction is likely to be the most
toxic and bioavailable. Estimates of the concentration of aqueous species
of metal present during the bioassays would begin to provide a basis for
setting standards based on the toxic species. This is essentially the
procedure Andrew et al. (1977), Chakoumakos et al. (1979) and Allen et al.
(1980) used to identify the toxic metal species in their bioassays. While
it is realized that the key information required to do this, namely the
chemistry of the dilution waters, may not be available for most of the past
bioassays, the use of a geochemical model like MINTEQ during the performance
of future bioassays should be considered so that an improved toxicity data
base can be developed.
The final application is a more subtle, but equally important, one. It
involves the use of MEXAMS as a framework for identifying what is and what
is not known about the behavior of priority pollutant metals in aquatic
systems. One of the overriding philosophies in developing MEXAMS was to
produce a tool that is not only applicable with existing data sources, but
also one that helps guide the collection of data in the future. An example
of this is the range of options available for calculating adsorption in
MINTEQ. The activity Kd, activity Langmuir or Freundlich options can be
used given existing data in the literature. The use of the constant
capacitance or triple layer models, however, may require the collection of
21
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new data. As these data become available, our ability to predict the
effects of adsorption will improve. Thus, the model (i.e., MINTEQ) will
help identify the critically important data, and guide future research and
the collection of better data.
LIMITATIONS
Despite the many capabilities that both MINTEQ and EXAMS offer, there
are several limitations that the user must be aware of prior to applying
MEXAMS. First, the thermodynamic data base associated with MINTEQ only
contains equilibrium constants and accessary data for the following priority
pollutant metals: As, Cd, Cu, Pb, Ni, Ag and Zn. Some data on the other
metals (i.e., Sb, Be, Cr, Hg, Se and Th) exist in the literature. However,
before they can be included in the data base, the data should be carefully
evaluated. One of the key areas in geochemical modeling is the quality of
the thermodynamic data bases associated with different models. Considerable
resources and care have gone into the construction of the MINTEQ data
base. It is continually being updated as new and better data are found in
the literature. Data for other constituents, some of them priority
pollutant metals, are being included under related research programs. At
this time, however, the user can only analyze the above metals, unless of
course the user has access to or has collected other thermodynamic data.
The second limitation relates to organic complexation. In many natural
waters this phenomena can have a major impact on the speciation of metals.
While MINTEQ is computationally capable of considering organic complexation,
the thermodynamic data base does not contain the necessary equilibrium
constants and accessary data. Again, the literature does contain some
22
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thermodynamic data on organic complexation of selected metals. These data
need to be reviewed and evaluated before inclusion. MISP can be used to
enter tnese data, if they are available to the user.
Another limitation of MINTEQ, and most other geochemical models, is
that it treats precipitation/dissolution, oxidation/reduction and adsorption
as equilibrium processes, when in fact they may not be in equilibrium. In
the area of precipitation/dissolution, some literature data are available on
the rates of formation and dissolution of selected solids. However, these
data are relatively scarce. Thus, there is a need to experimentally measure
the rates of formation and dissolution for those solids that are likely to
control metal solubilities in natural waters. There is also a need to
include these data in the data base and incorporate a kinetic algorithm in
MINTEQ. The kinetics of oxidation/reduction reactions are not well
understood. Redox reactions are frequently biologically mediated and rarely
in equilibrium. As a result, the equilibrium approach used in most
geochemical models can only provide boundary conditions towards which a
system is proceeding. It is not clear how important the kinetics of
adsorption are for metals. Most constituents tend to adsorb quite rapidly
(i.e., within hours), but desorb less rapidly. As in the case of
precipitation/dissolution kinetics, there are some data available on the
kinetics of adsorption for selected metals. These data need to be included
in the data base and supplemented with experimental work.
A final limitation is the degree of testing MEXAMS has received. While
both MINTEQ and EXAMS have been tested on and applied to a number of prob-
lems, the linked system of models has received limited testing. MEXAMS has
only been tested using the relatively simple problems that are described
23
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later in this manual. For this reason, users should exercise extreme care
in the early stages of applying MEXAMS. Eventually, MEXAMS should be more
rigorously tested on a series of hypothetical and site-specific problems.
24
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SECTION 5
A PRIMER ON KEY CONCEPTS IN AQUEOUS CHEMISTRY
It is necessary to first introduce some elementary chemical concepts in
order to understand, use and interpret the results obtained from MEXAMS.
This section provides an introduction to aqueous speciation, activity,
adsorption, and solid phase reactions.
AQUEOUS SPECIATION
The total dissolved fraction of a metal consists of several aqueous
species. As an example the possible dissolved species of lead in a water
containing nitrate, chloride, sulfate, fluoride and carbonate are shown in
Table 1. The total dissolved concentration of lead is then the sum of the
concentration of all aqueous species of lead. Equation (1) gives a mass
balance for lead.
Pb total .dissolved = m Pb'+ + m Pb
-------
TABLE 1. DISSOLVED SPECIES OF PB
Pb2+ PbCl+
Pb(OH)2 (AQ) PbCl2 (AQ)
Pb(OH)-3 PbCl3"
Pb2(OH)3+
Pb3(OH)2+
PbF+
PbS04(AQ) PbF2(AQ)
Pb(C03)2~ PbFf"
The quantity of each individual species in Equation (1) can be
calculated using mass action expressions. Ignoring the difference between
the thermodynamic activity and concentration, the formation reactions for
the species PbOH+ and PbCl2+ are
Pb2+ + H20 : PbOH+ + H+ , KpbQH+ (2)
Pb2+ + CT : PbCl+ , KpbC1+ . (3)
Equations (2) and (3) may be rewritten to yield the mass action
expressions,
[PbOH+] [H+1 _ „
+
^ ] [H90]
26
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[PbC1+]
[Pb+] [Cl"]= KPbCl+
where brackets indicate concentrations.
The formation reactions for the species in Table 1 can be conveniently
expressed in terms of [Pb2+], [H+], [H20], [CT], [SO2/], [F-], [NO^J,
[COg"] as well as the equilibrium constants (K) for each species. An
important point to note is that the concentration of species which comprise
the total dissolved lead in solution depends upon [H+], [Cl~], [SO2."], [F~],
[NOg] and [CO2,']. In the example, if these constituents (i.e., pH,
chloride, sulfate, fluoride, nitrate and carbonate) are not determined in a
water analysis, an inaccurate aqueous speciation calculation could result.
Redox reactions are also related to the mass balance equations and mass
action expressions in, a similar manner to those just presented. Table 2
presents the aqueous species of iron in a solution containing only chloride,
phosphate and sulfate. Since, in an aqueous solution, iron can exist in two
oxidation states, two mass balance equations can be written, one for each
oxidation state.
Fe(n)total, dissolved=mFe+2+mFeOH+- • • •
Fetotal, dissolved=mFe+3+mFeOH2+- ' - <
In this notation Fe(II) will represent the total dissolved iron in
oxidation state (II) and Fe2+ will represent only the concentration of the
individual species Fe2+. All of the species of Fe(II) can be written in
27
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TABLE 2. AQUEOUS SPECIES OF IRON
Fe(II)
Fe(III)
Fe2+
FeOH+
Fe(OH)3
Fe(OH)2(AQ)
FeH2P04+
FeHP04(AQ)
FeS04(AQ)
Fe3+
FeOH2+
Fe(OH)2
Fe(OH)3(AQ)
Fe(OH)4
Fe2(OH)4+
Fe3(OH)5+
FeHPOj
FeH2PoJ+
FeF2+
FeF2
FeF3(AQ)
FeS04+
Fe(S04)-
Fed
Fed
2+
FeCl3(AQ)
terms of Fe2+ and all species of Fe(III) can be written in terms of Fe3+
using mass action expressions. The two oxidation states are then linked by
the redox reaction for Fe2+ and
Fe
3+
Fe
2+
(8)
resulting in the mass action expression,
[Fe2+]
[Fe3+]
KFe2+,Fe3+
(9)
28
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Equation (8) is written between the species Fe^+ and Fe^+ and not
between the total concentrations of Fe(II) and Fe(III). The use of
Equation (9) and knowledge of the Eh or pE will allow total dissolved iron
to be correctly partitioned into the species shown in Table 2.
ACTIVITY
The concentration of a species is related to the thermodynamic activity
by the activity coefficient.
[Pb2+ ] y 9= (Pb 2+) (10)
PIT
where brackets denote concentration, y is the activity coefficient and { }
denotes activity. The difference between activity and concentration can be
thought of as analogous to the difference between ideal and real gases. The
activity coefficient takes into consideration interactions between charged
ions and ion interaction with the bulk solution. The activity coefficient
varies with: species charge, species size, temperature and ionic strength
i=4- y m z? (ID
^ !
where
mi = concentration of species i
Z-j = charge of species i
n = total number of species in solution
29
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Since charge, ion size and temperature are usually fixed the most
important variable in activity coefficient calculations is usually ionic
strength. In very dilute solutions where the ionic strength is approxi-
mately zero the activity coefficient is approximately one and concentration
equals activity. However, as ionic strength increases the activity coeffi-
cient can become very small and the concentration can be as much as two
orders of magnitude larger than the actual activity. Since the activity is
the true thermodynamic value all of the equilibrium constants, which have
been previously described, are only valid when expressed in terms of
activities rather than concentrations. As a result, the determination of
the ionic strength is important in determining activity coefficients, the
resulting activities and the overall modeling results.
ADSORPTION
Adsorption can be thought of as analogous to aqueous speciation since
the solid phase has surface adsorption sites which react with solution
species. Equation (12) is a mass action expression for lead adsorption.
W+P^^ and ^._^_ (12)
where SO" represents a surface site, SOPb+ represents a surface bound Pb2+
ion and Ksopb+ represents the equilibrium constant for the reaction.
The mass balance for lead can now be rewritten to include adsorbed
species, Equation (13).
30
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Pb = mPt)2+ + m PbOH+ • • • • + m Wb^ . (13)
total
Equation (13) is now written in terms of dissolved plus adsorbed lead
rather than total dissolved lead, Equation (1). The total adsorbed and
dissolved lead does not include lead precipitates, such as PbCC^s).
Formulating adsorption reactions in an analogous manner to aqueous
speciation reactions also introduces a mass balance equation for available
adsorption surface sites (Equation 14).
S0total = SO + SOH + SOTH; . . .IJOPT . (14)
Unfortunately, this simple concept of adsorption ignores an important
difference between adsorption onto solid phases and aqueous speciation,
i.e., the general presence of an electrical charge on the solid surface.
This charge creates an electrostatic potential between the surface and bulk
solution. The charge and electrostatic potential can markedly effect
adsorption and alter the simplistic concept presented here. Section 4 of
the MINTEQ technical document discusses this further.
SOLID PHASE REACTIONS
A solid phase can also be represented by a formation reaction and mass
action expression, e.g.,
Pb2+ + CO2" + PbC03(s), and (15)
31
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(PbC03(s)}
9+ 7
(Ptr } {C03 }
where {} denotes activity.
If the pure solid phase is present, then the activity of PbC03(s) is
unity. This leads to the concept of a saturation index for a solid phase.
The concept of a saturation index is easier to understand if the reaction
for the solid is written as a dissolution reaction, Equation (17).
Pbco3(s): Pb2+ + co32-
with the mass action expression,
{Pb2} {CO2'}
(PbCU3(s)} ' = KPbC03(s) (18)
A simple rearrangement of Equation (18) and taking logarithms yields
Equation (19).
log SI = log AP/K (19)
where
AP = activity product ({Pb2+} (CO2"}), and SI = saturation index.
32
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At equilibrium log SI will of course equal zero, Equation (19). If the
solid phase is undersaturated, then log K > log AP and log SI is negative.
If the solid phase is supersaturated, then log K < log AP and log SI is
positive.
The saturation index is a very useful indicator of the tendency of a
solid to dissolve or precipitate or of how close the solid is to
equilibrium. However, it does not mean the solid will actually dissolve or
precipitate. Kinetic factors may prevent the solid from ever actually
attaining equilibrium in the time frames of interest. Therefore, when using
a geochemical model it will be very important to carefully choose which
solids will be allowed to dissolve or precipitate. Allowing the model to
dissolve or precipitate solids that will not reach equilibrium in the time
frames of interest can lead to erroneous results. Some general guidelines
for selecting solid phases will be presented in Section 6.
33
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SECTION 6
GUIDELINES FOR USE
Section 6 presents the user with detailed guidelines for the use of
MEXAMS. It starts by presenting the modifications made to the EXAMS model
in order to link it with MINTEQ, as well as data input procedures which
supplement those provided in the EXAMS user's manual. Next, it discusses
the user options and general data requirements for MINTEQ. This is followed
by step-by-step procedures for entering data into MEXAMS using MISP. The
section concludes by outlining the types of output available from MEXAMS and
typical responses to error messages.
USE OF EXAMS
The use of EXAMS is covered in detail in the EXAMS user's manual and
documentation report.(a) This discussion will not attempt to duplicate what
is already provided in this report. Rather, it will focus on the modifica-
tions that were made to EXAMS in order to link it with MINTEQ. All of the
modifications discussed below are for the batch version of EXAMS. The
(a) Burns, L. A., D. M. Cline and R; R. Lassiter. Exposure Analysis Modeling
System (EXAMS): User Manual and System Documentation. U.S. Environmental
Protection Agency, Athens, Georgia. EPA-600/3-82-023.
34
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specific coding changes made to each subroutine in EXAMS are discussed later
in Section 7, the Programmer's Supplement.
EXAMS Modifications
Modifications to EXAMS are transparent to the user familiar with the
original code. All changes are internal and do not affect computations
performed without the geochemical code coupling: the capability of the
modified version of EXAMS is exactly the same as the unmodified version.
Basically two types of modifications were made to the EXAMS model. The
first type involved by-passing those calculations that were unnecessary for
heavy metal ions or duplicated by MINTEQ. The second type involved
additions to account for the migration and fate of the precipitated
fraction. Specific modifications included:
1. Since MINTEQ computes the concentration of dissolved species present in
each compartment, there is no need to consider ionization in EXAMS. In
reviewing the code it was found that the ionization computations could
be by-passed through the proper selection of model inputs.
2. Since MINTEQ computes the quantities of metal sorbed to sediments and
biota for each compartment, there is no need for EXAMS to make this
calculation. Again it was found that this modification could be
handled through the proper selection of inputs, as opposed to the
modification of the code. Supplemental input procedures for this
modification are also discussed later.
35
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3. The unmodified version of EXAMS limits the solubility of a chemical to
either less than 50% of its aqueous solubility or 1 x 10"5 M for the
dissolved neutral form of the chemical. Thus, it does not allow for
precipitation. In the modified version of EXAMS, these limitations are
by-passed. In addition, the bookkeeping algorithm in EXAMS which keeps
track of the quantities and forms of chemical present in each
compartment was expanded to include the precipitated fraction. This
involved expanding the ALPHA matrix so that ALPHA(16) is now the
precipitated fraction. The dissolved, sediment-sorbed and biosorbed
fractions are now ALPHA(17), ALPHA(18) and ALPHA(19), respectively,
instead of ALPHA(16), ALPHA(17) and ALPHA(18). Wherever these
quantities were used in the code they were changed.
4. EXAMS will compute steady-state metal concentrations by solving the
following equation:
Le + L. - VKC = $ = 0 (2Q)
where
C = total metal concentration
K = overall pseudo first order loss constant that expresses combined
effects of transport and volatilization
Le = total external loading on the compartment
Lj = total internal loading on the compartment
V = water volume in the compartment.
36
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In order to account for the migration of the precipitated fraction it
was assumed that it could be transported as a sediment-sorbed
fraction. This did not require any changes be made to the transport
equation, but did require modifying the calculation of the internal
chemical loading (L-j) for each compartment. L^ is now calculated as
follows:
L. = C * [ALPHA(17) * SUMWAT + (ALPHA(16) + ALPHA(18)]
ALPHA(19) * SUMWAT * PLRAG]
where
L.J = total internal loading for the ith compartment (mg/hr)
C = total metal concentration (mg/1)
ALPHA(16) , ALPHA(17) , ALFHA(18) , and ALPHA(19) = fractions of
precipitated, dissolved, sediment-sorbed and biosorbed metal,
respectively;
SUMWAT = total water discharge
SUMSED = total sediment discharge
SEDCON = sediment concentration per unit volume of water
PLRAG = fraction of biomass in a compartment.
5. Dispersion processes for metals in the modified EXAMS are expressed in
the same way as in the original EXAMS, except for the dispersion
between water and benthic columns. In this case, a portion of the
37
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return "flow" (SEDFL) of suspended sediment from the water compartment
to the benthic compartment, due to dispersion, is computed in the
modified EXAMS as:
ALPHA(17,W) * SEDCOL(W) „ ALPHA(16.b) + ALPHA(18,b)
SEDFL = TEMSED * ALPHA(l6,W) + ALPHA(l8,W) ALPHA(17,b) * SEDCOL(b)
WATVOL(W) ^ DSPG * XSTURG
TEMSED = SEDCOL(W) * VQLG(1^)/ * CHARLG
where
b,W = values in water and benthic compartments, respectively
CHARLG = characteristic length
DSPG = dispersion coeffient
VOLG = volume of a compartment
WATVOL = water volume
XSTURG surface area.
6. Metals are largely unaffected by the transformation and degradation
processes which govern the fate of organics in natural waters. For
this reason, these processes are bypassed in the modified version of
EXAMS whenever the metal option is exercised.
Supplemental Input Data Procedures
Since no new input data are required for the modified version of EXAMS,
the input data procedures for the original EXAMS can be used. Section 3.4
of the original EXAMS user's manual provides procedures for the preparation
of batch input data. One need only select the generic heavy metal as the
chemical to be modeled; loadings and environments are input in the original
manner.
38
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MINTEQ TUTORIAL
To learn to use MINTEQ, begin with a single hypothetical problem (such
as 0.01 molar solution of Na+ and Cl"). In this way, the large number of
input options will not be overwhelming.
The first step is to learn to prepare MINTEQ input data. There are two
methods of preparing MINTEQ input files: 1) the input file can be prepared
directly utilizing the file description given in Appendix C, 2) a user
interactive routine in MISP can be used to prepare the input files.
Experienced users will find the first option preferable because the
user interactive routine in MISP is lengthy. However, beginning users will
find the user interactive routine helpful in defining the data needs for
MINTEQ.
To use the interactive routine type,
"RUN MISP ",
and select the MINTEQ only mode without EXAMS (Option 2). Answer, 'N', when
asked if a data file is ready. Next, a series of questions will appear on
the screen. These questions are described in detail in the "DATA INPUT TO
MEXAMS USING MISP" section. There are a total of 55 questions in this
routine; for this simple hypothetical problem you will want to give the
following responses.
Question No. 1: Enter title of simulation
Answer: 0.01 molar NaCl solution
Question No. 2: Enter description of water body.
Answer: hypothetical solution
39
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Question No. 3: Select data units
Answer: select molality (MOL)
Question No. 4: Enter temperature (degree centigrade)
Answer: 25.0
Questions Nos. 5 through 10:
Answer: N
Question No. 11: How many iterations will you allow?
Answer: select 40 (option 0)
Questions Nos. 12 through 13:
Answer: N
Question No. 14: Enter debug option number.
Answer: No debug (option 0)
Questions Nos. 15 through 25:
Answer: N
40
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Question No. 26: Does your sample contain CL?
Answer: Y
Enter total CL>
Answer: 0.01
Do you want to guess the activity of CL?
Answer: N
Questions Nos. 27 through 36:
Answer: N
Question No. 37: Does your sample contain NA?
Answer: Y
Enter total NA>
Answer: 0.01
Do you want to guess the activity of NA?
Answer: N
Questions Nos. 38 through 55:
Answer: N
After you have completed this question/answer session, select the
"MODEL DATA" option. When the program has finished, a copy of the output
will be in file MINTEQ.OUT.
At this point, the sections "USE OF MINTEQ" and "DATA INPUT TO MEXAMS
USING MISP" should be reviewed. Later, the interactive routine can be used
to create different MINTEQ input files (select the store data in a file
option) and the file structure can be compared with the description given in
41
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Appendix C. In this way, it will be much easier to learn the procedure
given in Appendix C and also to gain familiarity with the different species
type designations.
An example of using MEXAMS in the MINTEQ-EXAMS mode is given in the
MEXAMS implementation test case.
USE OF MINTEQ
MINTEQ offers a number of options which provide a great deal of flexi-
bility in the way the user defines the chemistry of the system being
modeled. These options make it possible for the user to apply MINTEQ to a
very large and diverse problem set. Thus, while not all of the options
discussed below are required to use MINTEQ to evaluate the behavior of
metals, it is important that the user be aware of these options when
preparing input data files.
Description of Species Types
The chemical species in MINTEQ are assigned one of six different spe-
cies type designations (Westall et al. 1976). In addition to facilitating
mathematical computations, these species type designations provide the user
with the ability to solve a broad range of chemical equilibrium problems.
Type I Species - Components--
Components are defined as the chemical species that are chosen to
represent each chemical constituent in the water analysis. For example,
Zn2+ is the component for zinc or Cd2+ for cadmium. Choosing charged
species as components does not conflict with Gibbs original definition of
42
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components, since there are no restrictions that components must be the
elemental forms (Westall et al. 1976). One component is designated for each
oxidation state for the redox sensitive elements included in the MINTEQ data
base. Iron then has two components, Fe2+ for iron in oxidation state (II),
and Fe3+ for iron in oxidation state (III).
A complete list of components in MINTEQ along with their designated
I.D. numbers is given in Table 3. The first two digits of the I.D. numbers
represents the alphabetic order of the chemical symbol of the element in the
periodic table and the -third digit is an arbitrary designation. As an
example, if the chemical symbols for all elements in the periodic table were
put in alphabetical order, Ag (silver) would be second and the ID number
would be 020.
The selection of components is somewhat arbitrary with the only
restriction being that a component cannot be a combination of two other com-
o
ponents. As an example both 003 and HC03~ could not be chosen as com-
ponents for inorganic carbon since HCO^ can be formed from COg^- and H+.
The only exception to this general rule is for redox sensitive elements
since the electron does not actually exist in solution.
Designating a set of components allows the mass action expressions to
be written in terms of components, Equation (21).
Pb
2+ + Cl" t PbCl+ (21)
The chemical equilibrium problem then reduces to finding the activity
of each component that correctly satisfies the mass balance constraints.
43
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COMPONENTS IN MINTEQ
Component
E
H?0
Ag+
A13+
HoAsOi
HoAsOi
HoBOi
Ba2+
Br".
C03
FuTvate
Humate
Q(j2+
ci-
Cs++
Cu
Fe2+
Fe3+
H+
r
K+
Li +
Mg2+
Mn2+
Mn3+
I.D.
Number
001
002
020
030
060
061
090
100
130
140
141
142
150
160
180
220
230
231
280
281
330
380
410
440
460
470
471
Component
NH4+
N02"
Na^
Ni ^+
PO|~
'Pb
Rb+
HS"
SO2",
H4^34
U3+
U4+
uot
uojf
Zn^+
SOH1
SOH2
XPSIO
XPSIB
XPSID
SOHB
I.D.
Number
490
491
492
500
540
580
600
680
730
731
732
770
800
890
891
892
893
950
990
991
992
993
994
995
Type II - Complexes—
All aqueous species which are combinations of two or more components
are Type II complexes. Some examples of complexes are shown in Table 4
along with their ID numbers.
The ID numbers for complexes are seven digit numbers with the first
three digits representing the ID number of the cationic component and the
44
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TABLE 4. AQUEOUS COMPLEXES
Complex ID
PbC03(AQ) 6001401
PbCl+ 6002800
CdHC03+ 1601400
NiS04(AQ) 5407320
next three digits representing the anionic component. The last digit is an
arbitrary designation.
Type III - Fixed Species--
Any species with a fixed activity is a Type III species. It is
important to note that solids and gases are also species.
Fixed species are commonly of four types:
« components present at a fixed activity such as the pH or pE,
* solid phases which are present in infinite supply,
« gases present at a fixed partial pressure, and
« redox reactions between two components.
45
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Redox reactions are included here because they represent a fixed
activity ratio of the components, Equations (22) and (23),
{Fe3+} +{e-} t (Fe2+l , K (22)
Fe ,Fe^+
(Fe2+) _ K , -, (23)
T ~ N -5 o ^
Type IV - Precipitated Solids Subject to Complete Dissolution--
Type IV species are identical to Type III solid species except these
solids have a finite mass. If during the computations the entire mass of a
solid dissolves, then the fixed activity relationship between the components
is removed. If, however, during ensuing computations the solid becomes
oversaturated, the solid can be precipitated and the fixed activity
relationship between the components reestablished.
Type V - Dissolved Solids Subject to Precipitation--
Type V species are solid phases which can precipitate if they become
oversaturated. The terminology of "Dissolved Solids" or "Precipitated
Solids" can be confusing. Precipitated solids are physically present and
have a fixed activity. A dissolved solid is not physically present. The
saturation index will be checked to see if the solid should be precipi-
tated. When a Type V solid is actually precipitated by MINTEQ, it becomes a
Type IV species.
I.D. numbers for solids are seven digit numbers. The first two digits
correspond to the mineral group and roughly follow the mineralogical classi-
fication in Dana's system (Dana and Ford 1957) and that described by Robie
46
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et al. (1978). The mineral group I.D. numbers are given in Table 5. The
next three digits represent the leading cation in the chemical formula and
the last two digits are arbitrary designations. Table 6 presents some
examples of solid phases and their corresponding I..D. numbers.
Type VI - Species Not Considered--
Type VI species are not considered during equilibrium computations.
These species are "considered" only after the equilibrium problem has been
solved. As an example, the thermodynamic data for an aqueous complex may be
suspect and the user may wish to know the affect on the aqueous speciation
if the complex were not considered. In such cases the species can be given
a Type VI designation.
TABLE 5. MINERAL GROUP I.D. NUMBERS
00 elements
10 sulfides
20 oxides and hydroxides
30 multiple oxides
40 bromides
41 chlorides
42 fluorides
43 iodides
50 carbonates
51 nitrates
52 borates
60 sulfates
70 phosphates
72 arsenates
73 vanadates
80 orthosilicates
82 chain silicates
84 framework silicates
86 sheet silicates
47
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TABLE 6. SOLID PHASES AND ID NUMBERS
Solid I.D.
Aragonite 5015000
Calcite 5015001
BaF? 4210000
Bante 6010000
Dolomite 5015002
Hematite 3028100
Type Modifications
The default designation for components and aqueous complexes in the
MINTEQ data base are Type I and II, respectively. There are no default
Type III or IV species. Redox reactions and reactions involving gas phases
have default Type VI. The solid phases and minerals can be either default
Type V or default Type VI depending upon user input options. The user can
override the default type designation by modifying the species type. The
default type is determined by the location of the species data in the data
files. See the Programmer's Supplement for details.
The following discussion presents some specific examples of how to
modify the species type designations and equilibrium constants to solve
certain types of problems. The user interactive routine in MISP can perform
many of these modifications. However, this routine is lengthy and has
limited error recovery ability; it should only be used only to help learn
how to prepare MINTEQ input files. The examples presented here will be
useful when preparing MINTEQ input files.
48
-------
Gas at a Fixed Partial Pressure--
To specify a gas at a fixed partial pressure it is necessary to
designate the species type for the reaction containing the gas as Type III
and for the user to modify the equilibrium constant to reflect the partial
pressure of the gas. Equations (24) through (29) presents an example for
at a fixed partial pressure of 10"3'5 atmospheres.
CO^" + 2H+ t C02(g) + H20 log K = 18.16 (24)
PCO? (H2°}
* K
?- + ?
6 (HV
{H?0}
-«-= 77-9- =-p-^- = K when Prn = 1.0 (26)
),"> (H } C00 LU2
o " d
(27)
log K' = log K - log P (28)
Lf U r\
assuming Prn = 10" * '
uu2
log K = 18.16 - (-3.5) = 21.66 (29)
The user would give the reaction for C02(g) a Type III designation and
specify an equilibrium constant of 21.66. This example might represent a
surface water in equilibrium with atmospheric carbon dioxide.
49
-------
Fixed pH--
The activity of a component can also be fixed in a similar manner. To
fix the pH at 8.00, designate H+ (ID 330) as a Type III species and modify
the equilibrium constant. Equations (30) through (32) present this
example. Equation (30) shows that a component is treated as a species on
the right side of the equation and as a component on the left side.
Hj = H*. log K = 0.00 (30)
itLLL= K, since {H+} = 1 (31)
(H+}c
{H+}c • K = 1 (32)
log K = - log (H+>c
log K = - (-8.00) = 8.00
to fix the pH at 8.00 give H+ a Type III designation with a new log K of
8.00.
Compute the pE from Fe(II) and Fe(III)--
In the case where direct analytical data for total iron in oxidation
states (II) and (III) are available the pE can be computed. This
computation may be useful if redox potential measurements are not available
or the user wants to see if Fe (II) and Fe (III) are in equilibrium with the
measured redox potential. The modification simply involves designating Fe2+
and Fe^+ as components and entering the appropriate mass totals. Enter the
50
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electron as a component (ID = 001) and change the type to Type VI since the
electron has no mass in aqueous solution.
Enter an "Activity" Kd
The first requirement for including an "activity" Kd is that the
original solution in which the standard Kd was determined must first be
modeled by MINTED, in order to obtain the activity of the ion of interest.
To model the solution in MINTED, merely enter the dissolved equilibrium metal
concentration and all experimental water quality data such as the pH and
alkalinity. MINTED will compute the activity of the uncomplexed ion.
The adsorption reaction can be thought of as a reaction between the
uncomplexed ion and the surface,
Cd2+ + 3Ud . (33)
_ _ 2+
Where S stands for a surface site and SCd is surface bound Cd2+. The
activity Kd is then:
= "activity" Kd (34)
Equation (34) is simply the amount of cadmium adsorbed divided by the
activity of the Cd2+ species in solution. The problem is now trivial,
include SOH1 (a surface site component which represents S) as a Type III
2+
fixed species and inert SCd as a Type II species. An important point
remember when dealing with adsorbed species is that the species ID number
51
-------
must be greater than 9900000 or the mass adsorbed will be incorrectly
computed. The ID number allows MINTED, to differentiate between adsorbed and
aqueous species for activity coefficient calculations.
Selection of Adsorption 'Models
MINTEQ contains six algorithms for calculating adsorption: 1) an
"activity" Kd, 2) an ion exchange model, 3) an "activity" Langmuir isotherm,
4) an "activity" Freundlich isotherm,(a) 5) the constant capacitance double
layer model and 6) the triple layer site binding model. The selection of
which model to use depends upon the site conditions, the desired accuracy of
the simulation and the availability of data. The reader is referred to the
MINTEQ technical document for details of each model. Only a brief
discussion is presented here..
The "activity" Kd should give a reliable estimate of adsorption, as
long as the surface chemistry of the solid adsorbent remains relatively
constant and the pH and ionic strength remain constant. In other words, as
long as the surface properties of the adsorbent remain constant, the
"activity" Kd will probably give reliable results. In locations where the
pH or ionic strength are variable, the "activity" Kd should not be used.
The ion exchange model will be useful if selectivity coefficients for
exchange reactions are available. However, selectivity coefficients will
generally be available only for bulk electrolyte ions such as Na+, K+ and
(a) Available only on the VAX version of MINTEQ
52
-------
o ,
Cad . Metal adsorption is probably a result of forming covalent bonds with
surface sites and thus can not generally be predicted by an ion exchange
model.
The "activity" Langmuir has the advantage over the "activity" Kd in
that a mass balance on surface sites is considered. This means that at
relatively high metal loadings the "activity" Langmuir will probably give
more reliable results than the "activity" Kd as long as the solution pH
remains relatively constant. Langmuir isotherm data are available for a
number of soils but generally not for stream sediments. To convert regular
Langmuir isotherm data to an "activity" Langmuir requires modeling the
solutions used in the laboratory study with MINTEQ in order to obtain the
activity of the uncomplexed ion or binding species. The isotherm must then
be replotted to obtain the '"activity" Langmuir K and the total surface
•
sites.
The "activity" Freundlich can be used if the laboratory data do not
conform to the "activity" Langmuir.(a) Again to determine the "activity"
Freundlich parametrs requires modeling the laboratory solutions with MINTEL)
to obtain the activity of the uncomplexed or binding metal ion. Data for
conventional Freundlich isotherms are available for many soil types but
generally not for stream sediments. C3)
(a) To conform to the "activity" Langmuir model a plot of activity uncomplexed
ion/amount sorbed versus activity uncomplexed ion should yield a straight
1 ine.
(b) The "activity" Freundlich isotherm is not included in the POP 11/70 version
of MINTEQ.
53
-------
If data for either the "activity" Langmuir or "activity" Freundlich are
available they should be used instead of the "activity" Kd because the iso-
therms consider the effects on adsorption of variable metal concentrations.
However, neither isotherm can theoretically handle changes in surface pro-
perties resulting from changes in solution pH, ionic strength or variable
solid to solution ratios.
The constant capacitance and triple layer models are based on a
theoretical approach and should be superior to the "activity" Kd or "activ-
ity" isotherms. These models consider charge-potential relationships at the
surface and the changing properties of the surface as a result of changes in
pH or ionic strength. However, they also may require specific experimental
work to obtain the necessary parameters. For example, to obtain the neces-
sary data for the constant capacitance model at a fixed ionic strength would
• *
require as a minimum:
<•> titration curves of the solid phase at least at one ionic strength and
no element of interest (metal) present
t titration curves of the solid in the presence of at least one
concentration of the element of interest (metal )
» some estimation of total surface sites and specific surface area
If the user wishes to predict adsorption at different ionic strengths a
second titration at a different ionic strength with no metal present would
be required.
The constant capacitance and triple layer models have been applied to
single oxide systems and mixtures of oxides with considerable success.
However, they have only recently been applied to heterogeneous solids such
as soils or sediments. Further work should be done but the models should
54
-------
provide more accurate results than the simple "activity Kd" or "activity"
isotherms especially in systems where the majority of adsorption sites are
on hydrous oxides. For further information on these adsorption models see
Section 4 of the MINTEQ technical documentation report.
Biosorption can be considered by using the "activity Kd" model. The
biosorption coefficient should be corrected for the activity of the compo-
nent in solution and computed in the same manner as the "activity" Kd. The
only difference is the surface site (SOH) should be assigned an I.D. number
of 995. As in EXAMS, this option has been provided so that users, can evalu-
ate the relative importance of this mechanism. It has not been tested or
evaluated in a theoretical sense.
In summary, MINTEQ is structured to allow the user the flexibility of
using as much data as are available. If the system being studied has a
relatively constant pH and ionic strength, the metal concentrations are
relatively low and only limited adsorption data for that solid or sediment
are available, the "activity" Kd provides an adequate approach to model
metal adsorption. If, however, metal concentrations can be relatively high
and variable due to changes in metal loading then one of the "activity"
isotherms, either Freundlich or Langmuir, should be used. However, if the
solution pH and ionic strength varies,(a) data for the constant capacitance
or triple layer models should be obtained.
(a) pH should not vary by more than ±0.5 to 1.0 unit, ionic strength by ±20%
depending upon the system.
55
-------
Selection of Solid Phases^
To introduce this discussion, the difference between "selection of
solid phases" and "consideration of solid phases" must be defined. Selec-
tion of solid phases determines the solids which are actually going to dis-
solve or precipitate. These solids will be termed "selected solids" in this
section. The "consideration of solids" means the solids which were consid-
ered during the selection process. These "considered solids" will only dis-
solve or precipitate if they are "selected". In terms of the species types,
Type III and Type IV are "selected" solids, Type V are "considered" solids.
The user can of course arbitrarily select the solid phases and simply
declare them either Type III or Type IV depending upon the specific prob-
lem. This is the preferred method when MINTEQ is being used in a research
type mode where the user is asking a series of "What if " questions: such
as "What would the pH be in equilibrium with calcite ". However, when the
user does not know which solids are in equilibrium this approach is not
practical.
Generally it is best to allow MINTEQ to select the solids, particularly
when the number of solids considered during the selection process (i.e., the
number of Type V solids) is specified. MINTEQ will then select and equili-
brate the thermodynamically stable solids with the aqueous solution.
The problem with this approach is that the thermodynamically stable
solids tend to be highly crystalline and have considerable kinetic barriers
to precipitation. If such solids are selected the predicted aqueous phase
concentrations can be in error by orders of magnitude. The best technique
then is to limit the solids MINTEQ considers to a set of amorphous phases
without kinetic barriers to precipitation. This way MINTEQ will select and
56
-------
equilibrate the solution with the stable phases which will actually form.
Selecting solids in this manner means that the predicted aqueous concentra-
tions will be maximum concentrations since selection of more stable solids
would lower the aqueous concentrations. Table 7 presents a recommended list
of Type V solids for the priority pollutant metals in the MINTEQ data base.
Data Requirements
The interpretation of the results predicted by MINTEQ becomes more
reliable as the users knowledge of the system increases. In the case of
input data, the more data the user has on the water chemistry of the system
the more accurate will be the predicted results. This does not mean that
the user must have data for all of the components listed in Table 3. Many
components do not react with other components or are present in such low
concentrations that they do not alter the geochemistry of the particular
components being studied. With this in mind, the following discussion will
focus on the general importance of each input parameter with the hope that
the user can glean some ideas for the specific data requirements of any
given system. It must be recognized that no set of guidelines will work for
all environmental systems.
pH~
pH is the most important parameter required by MINTEQ. Unless the
analytical data are from a well defined laboratory system where the total
ionizable H, total H+ (see the MINTEQ technical document), is known, the pH
57
-------
Copper
ov
I.D.
Number
5023100
4223100
4223101
.2023100
4123101
5123100
2023101
7023100
7023101
6023104
5023101
5023102
I.D.
Number
4160000
4260000
6060003
1060001
2060004
5060000
60000
4360000
7060005
Name
CuC03
CuF2
CuF2«2H20
Cu(OH)2
Atacamite
Cu2(OH),N03
Tenorite
Cu3(P04)2
Cu3(P04)r3H20
CuS04
Malachite
Azurite
Lead
Name
Cotunnite
PbF,
Anglesite
Galena
Pb(OH)2(c)
Cerrusite
PbBr2
PbI2
PbHP04
l.U.
Number
4195000
5095000
5095001
4295000
2095000
5195000
7095000
1095000
6095004
6095005
6095006
4095000
4395000
I.D.
Number
5054000
2054000
7054000
1054001
6054001
Name
ZnCl2
Smithsonite
ZnC03-H20
ZnF2
Zn(OH)2(A)
Zn(N03)2 6H20
Zn3(P04)2H20
ZnS(A)
ZnS04-H20
Bianchite
Goslarite
ZnBr2-H.,0
ZnI2
Nickel
Name
NiC03
Ni(OH)2
Ni3(P04),
Mlllerite
Retgersite
l.U.
Number
5016000
4116000
4116001
4216000
2016001
2016000
7016000
6016003
4016000
4316000
Sil
I.D.
Number
4002000
4102000
5002000
4202000
4302000
7002000
1002000
6002000
Name
Otavite
CdCl2
CdC12-H20
CdF2
Cd(OH)2(c)
Cd(OH)2(A)
Cd3(P04)2
CdS04
CdBr2-4H20
CdI2
ver
Name
Bromyrite
Cerarygrite
Ag2C03
AgF-4H20
lodyrite
Ag,P0440
Acanthite
Ag2S04
Arsenic
I.D.
Number
7228100
'7215000
7231000
7210000
7247000
7254000
7260000
7290000
Name
FeAs04-2K20
Ca3(As04)2H20
Ba3(As04)2
Pb3(As04)2
Zn3(As04)2.2.5H20
58
-------
is an absolute requirement. Fortunately the pH is a commonly measured
parameter for almost all natural waters.
Eh (pE)-,
Eh is an important parameter for elements that have oxidation states
linked by redox reactions such as: Fe, Mn, Cu, As, and U. Unfortunately En
is seldom measured, and what data are available are usually only qualita-
tive. If measured Eh values are available, they should be used but remember
tneir qualitative significance.
There are numerous techniques for estimating the Eh: from solid-solid
reactions, from dissolved oxygen concentrations, from analytical data for
two oxidation states of an element or from the general concentrations of
redox sensitive elements such as Fe and Mn. Some of these techniques, such
as analytical data for Fe(II) and Fe(III), may work well. However, no
general guidelines can be presented for estimating Eh in all environmental
systems. Eh estimates should be made on a case by case basis. If the ele-
ments Fe, U, and As are not being considered it is probably better not to
estimate an Eh.
Temperature--
Temperature is a required input and must be in degrees Celcius. It is
not a sensitive parameter, however. If the input values are within a few
degrees Celcius of the actual value, significant errors will usually not
result.
59
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Ionic Strength--
The ionic strength is an optional input. Ionic strength will be
correctly computed by MINTEQ if concentrations of dominant cations and
anions are provided. Computing ionic strength is preferable since a more
accurate aqueous speciation is also computed. This also allows the ionic
strength to vary as solids precipitate or dissolve. However, if analyses
for the dominant cations and anions are not available, the ionic strength
can be estimated from specific conductivity (Lindsay 1979). In this case
ionic strength can be supplied to MINTEQ and activity coefficients can be
computed.
Major Anions--
? 2
Included in this category are Cl~, CO^ or alkalinity, SO^ and
H^SiO^. The most important of these are CO?" and Sof" because they
generally form strong complexes and precipitates with most major cations and
trace metals. Dissolved silica is also important because it can form
several insoluble precipitates but generally does not form significant
aqueous complexes with any cations except H+. Chloride generally forms weak
aqueous complexes. Chloride precipitates are generally very soluble and
become important only as the chloride concentration approaches that of
seawater. There are, however, exceptions to the rule. Silver and copper
can form strong chloride complexes whose precipitates are fairly insoluble.
Major Cations--
Included in this category are Ca2+, Mg2+, Na+, and K+. The most
important of these are Ca2+ and Mg2+ because they form fairly strong aqueous
60
-------
complexes and insoluble precipitates with anions such as: C0o2~, SO/,2-,
J H
P043" and F~. They are, therefore, important in obtaining a reliable
aqueous speciation. Ca2+ generally forms the strongest complexes and is,
therefore, somewhat more important than Mg2+.
Na+ and K+ are generally important only at high concentrations.
However they can be constituents of some relatively insoluble solid phases,
such as jarosites.
Trace Constituents —
Hydrogen sulfide (H^S)--Hydrogen sulfide is extremely important in the
geochemistry of trace metals (such as: Fe, Mn, Cu, Zn, 'Cd, Pb, and Ag),
because sulfide forms strong complexes and highly insoluble precipitates
with these metals. If the environmental system is reducing, H^s analysis
will be extremely important for accurately predicting trace metal
concentrations.
, Ortho phosphorus (P0d3")--Phosphorus is often analyzed as total
phosphorus, hydrolyzable phosphorus or ortho phosphorus. Ortho phosphorus
•3
is the important form for geochemical modeling. PO^ ~ analysis is most
important when considering trace metals or Fe, Ca and Mg. P043~ forms
strong complexes and insoluble precipitates with Fe, Ca and Mg. Because
PQa^~ also forms several insoluble trace metal precipitates, it is
important in the geochemistry of trace metals, especially Pb and Mn.
61
-------
Fluorlde(F')--Fluoride forms several aqueous complexes and solid phases
with trace metals. However, fluoride concentrations are generally low, and
fluoride will not effect the general geochemistry of the trace metals. How-
ever, if fluoride concentrations exceed a few mg/£, significant complexation
of trace metals can occur.
Iron and manganese—Except under low pH or Eh conditions, iron and
manganese generally do not affect the chemistry of the major cations.
However, iron forms strong aqueous complexes with several ligands, such as
^2$ and P0.3- which in turn also form strong complexes with trace metals
such as Cu, Zn, and Pb. Therefore, dissolved iron analysis will be
important in computing the correct trace metal aqueous speciation. The
aqueous complexes of Mn2+ are generally much weaker than the Fe complexes
and generally not as important.
A1uminum--Disso1ved Al is generally important only in the geochemistry
of silica, fluoride and phosphorus.
Barium and strontium—Ba2+ and Sr2+ are usually important only if these
constituents are being specifical-ly considered. However, Sr2+ is
occasionally present in high concentrations and in such cases can effect the
aqueous speciation of other constituents especially Ca2+ and Mg2+.
62
-------
Others—The constituents Cs + , Li+, Br~, B, NH|, Rb+, I" and NO^ are
important only in somewhat unusual circumstances. However B can be impor-
tant in the geochemistry of fluoride and is probably the most important
component of this group for computing aqueous speciation.
DATA INPUT TO MEXAMS USING MISP
The MEXAMS Interactive Software Program (MISP) queries the user to
obtain two types of information: 1) user run information and 2) MINTEQ
input data. The user run information determines which simulation mode will
be used (i.e., MINTEQ only, EXAMS only or MINTEQ coupled with EXAMS). It
also controls how the simulation results are tranferred back-and-forth
between MINTEQ and EXAMS. The MINTEQ input data describe the physical and
chemical characteristics within each compartment or set of compartments.
MINTEQ input files can be created by MISP in the MINTEQ only mode or
prepared directly with the information given in Appendix C. Before entering
the MINTEQ-EXAMS mode all necessary MINTEQ input files must have been
created.
In developing MISP, it was assumed that most users would be familiar
with the relatively straightforward procedures for creating an EXAMS input
file. The input data file for EXAMS contains an execution data set, a toxic
chemical database, and an environmental database. As mentioned previously,
no changes have been made to the manner in which data is entered in the
input data file. The only stipulation is that one must select the heavy
metal option, HVM, from the toxic chemical database when using the coupled
MINTEQ-EXAMS mode of simulation. The user is referred to the EXAMS user
manual and system documentation report for detailed descriptions of the
63
-------
input file procedures. Therefore, MISP does not query the user to create an
EXAMS input file. It does, however, request the name of the file the user
desires to use and transfers it to EXAMS.
If the coupled MINTEQ and EXAMS mode has been selected, then the
following questions will be asked.
Question No. 1: Select the metal ID from the following table.
Select the appropriate ID number from the list provided.
Question No. 2: How many MINTEQ input files will be needed?
Some of the compartments chosen for the EXAMS run may require different
MINTEQ water quality data. For example, the basic water quality in a river
may change as a result of an industrial discharge or at the confluence of a
major tributary. Different MINTEQ input files would then be needed for
these compartments.
Question No. 3: Enter no. of compartments for file n.
This question will be asked for each MINTEQ file. Enter number of
compartments the water quality data should be applied to.
Question No. 4: Enter compartment numbers for file n.
The actual compartment numbers for each MINTEQ file should be entered.
Question No. 5: How many times do you want to use MINTEQ to update the
steady state metal concentrations?
EXAMS initially assumes all of the metal is dissolved. By providing
these EXAMS results to MINTEQ, MINTEQ will recalculate the proper dissolved,
64
-------
sedimerit-sorbed, biosorbed, and precipitated metal concentrations. EXAMS
will then use these updated values of metal fractions in another simulation
of the transport and fate of the metal in the aquatic environment. This
MINTEQ-EXAMS interaction will be repeated the number of times specified in
this question.
Question No. 6: How often do you want to use MINTED for persistence
computations?
Select option number from the following list
(1) every time
(2) every other time
(3) every third time
(4) every fourth time
(5) every fifth time
(6) no persistence update
After the steady-state metal computations are computed, EXAMS will then
terminate the loadings of metal to the aquatic environment and calculate
subsequent reduced metal concentrations 12 times for an indication of metal
persistance. EXAMS will pause a specified number of times to obtain updated
dissolved, sediment-sorbed, biosorbed and precipitated metal concentrations
from MINTEQ. The above options allow the user to specify the number of
times this will occur.
65
-------
Question No. 7: Select MINTEQ output option.
Three choices will be provided:
1. full MINTEQ printout
2. aqueous species distribution and all mass totals
3. all mass totals
Option one will allow the full MINTEQ printout for every compartment
updated by MINTEQ. Option two will only print the dissolved, adsorbed and
precipitated totals and a listing of the important dissolved or adsorbed
species. Option three just prints the dissolved, adsorbed and precipitated
totals. Option one can result in a large volume of output so unless a
detailed description of the chemistry of the system is required, options two
or three should be selected.
Question No. 8: Enter name of MINTEQ input file n.
If all MINTEQ files are ready, then Question No. 8 will be asked for
each file, and each file will be copied in sequential order to the MINTEQ
input file named MINTEQ.INP.
Question No. 9: Enter EXAMS input file name.
MISP will copy the EXAMS input file to another file named FOR005.DAT
which is used by EXAMS.
The remainder of this discussion focuses on the series of questions
MISP poses to the user when creating MINTEQ input files in the MINTEQ only
mode. Each question is presented in the same sequence as they would appear
on a computer terminal along with a brief discussion of the type of response
that should be provided.
66
-------
When the user executes MISP to create MINTEQ input files in the MINTEQ
only mode, the following questions must be answered:
Question No. 1: Enter title of simulation
This line is for entering any identifying run specific information.
Any description can be entered to help differentiate this run from other
MINTEQ runs. The description must be less than 80 characters.
Question No. 2: Enter description of water body
This provides space for similar descriptive information as question
one. Enter whatever identifying information is appropriate for this run.
The description must be less than 80 characters.
Question No. 3: Select data units
There are four options: milligrams per liter (mg/£), parts per million
(ppm), molality or molarity (MOL) and mi 11iequivalents per liter (meq/2).
The units selected should be those used in the water analysis report. An
exception is alkalinity. MISP accepts alkalinity in milligrams per liter as
p
CaC03 and then converts it to the units designated here expressed as 003
before writing the MINTEQ data file.
Question No. 4: Enter Temperature (DEG. CENTIGRADE)
Enter the water temperature in degrees celcius. If you do not give a
value, MINTEQ will assume 0°C.
67
-------
Question No. 5: Will the ionic strength be input?
This option should be selected only if analyses of the dominant cations
and anions are not available. In such cases ionic strength can sometimes be
estimated from specific conductivity (see the data requirements section).
If this option is selected the program will ask for the ionic strength.
Question No. 6: Do you have either a measured pH or a value for the
TOTAL H+?
If you have a measured pH MISP will make all necessary type changes.
The TOTAL H+ stands for "total ionizable H+". You will very seldom know
TOTAL H+ unless you are dealing with well defined laboratory systems or have
made a previous MINTEQ run with a fixed pH in which case MINTEQ will have
computed TOTAL H+. In the latter case TOTAL H+ can be used to compute the
pH.
Question No. 7: If solids are selected to dissolve or precipitate do you
want to allow the pH to vary?
This option will allow the pH to change in response to solids
dissolving or precipitating. For this option to work all solids must have
originally been made Types V. This option is generally useful only in the
MINTEQ only mode when studying the water chemistry of the system.
Question No. 8: Do you have an Eh value or do you want to enter the
electron as a component?
If you do have a measured or estimated Eh the program will convert the
Eh to pE and make all necessary type changes. Entering the electron as a
-------
component without having a measured Eh is only useful in cases where the
mass total of individual oxidation states of an element are known. For
example, analytical data may be available for iron in both oxidation states
II and III. In such cases the electron should be entered as a component and
the corret pE will be computed.
Question No. 9: Do you have a total alkalinity measurement? (Y or N)
If a measurement of total alkalinity is available, the program will ask
for the alkalinity expressed as mg/L CaCO-j. The program will convert mg/L
CaCOj to the units you have designated in Question 3 expressed as C0?~.
o
Next, MISP will ask for a guess at the log activity of 003. Log activity
o
of CO^" will normally be between -4.0 and -8.0, depending upon such factors
as pH and the total alkalinity. If you do not enter a guess the model will
default to the analytical input divided by 100.(a)
Question No. 10: Do you have a measurement of total inorganic carbon?
(Y or N)
If you do have a TIC measurement the program will ask for the total
mass in the units designated in Question 3, expressed as COj . The program
•5
(a) If a solid phase containing CO-?" is in equilibrium with the solution
alkalinity should not be input. In such cases a modeling run should be
made with alkalinity input and solids not in equilibrium. This modeling
run will result in the computation of total inorganic carbon (TIC).
Another modeling run should then be made with TIC input and solids in
equi1ibri urn.
69
-------
will then ask for a guess at the log activity of C0^~. The same concepts
2
described in Question 9 also apply here relative to guessing the C03~
activity.
Question No. 11: How many iterations will you allow?
The options are:
1. 40
2. 10
3. 100
4. 200
The 100 or 200 iteration options should be selected if a large number
of solids will be designated as considered-sol ids (i.e., Type V). The ten
iteration option is only useful when debugging the program. If you are not
going to allow solids to dissolve or precipitate, the 40 iteration option
should be selected.
Question No. 12: Do you want to override the charge balance criteria?
If this option is selected MINTED, will terminate execution if the
initial charge imbalance between input cations and anions is greater than
30%.(a) This is a useful criteria since a large charge imbalance may be an
indication that one or more important constituents is missing from the water
analysis data. However, there are cases where this criteria should not be
applied. If for example, when the user has very limited environmental data,
(a) The actual criteria is [(r anion - r cations)/(E anions + r cation)]
<0.3.
70
-------
such as only the pH and total cadmium, and wishes to gain some information
about the system, he may ignore the charge imbalance. The second case may
be when the initial imbalance is very large due to the arbitrary assigning
of all the constituent mass to a component such as C032~ when actually the
solution is predominantly HCO^. In such cases the initial charge balance
checked here will exceed the criteria but the final aqueous speciation will
be within the criteria. In such cases the charge balance criteria should
not be considered.
Question No. 13: Do you want to allow all solids in the data base to
precipitate if they are oversaturated?
This is one of the most important questions in MISP. If you allow all
solids in the data base to precipitate then MINTEQ will check the saturation
indices for all the solids in the data base and select the thermodynamically
stable solids from these. If you do not allow consideration of all solids,
MINTEQ will select the thermodynamically stable solids froirrthe considered
solids entered later in this program in Question No. 51. It is recommended
that the user carefully read the discussion on the selection of solids in
Section 5, Guidelines for Use, before answering this question.
If you decide to consider all solids in the data base you will be asked
to select when you want the results printed, the options are:
1. print the results only after all solids are in equilibrium or
undersaturated and the problem is completely solved,
2. print the results after the aqueous speci'ation problem is solved and
again after all solids are undersaturated,
71
-------
3. print the results every time a solid is selected to dissolve or
precipitate.
If you are just beginning to use the model and are only interested in
the final chemistry of the solution, select option one. Options two and
three are only useful if the user is interested in analyzing the chemistry
in more detail.
Question No. 14: Enter debug output option number?
This option is useful only when MINTEQ is being ma.de operational on
different computers or when the user is interested in very specific chemical
or numerical processes. All other times the No Debug option should be
selected. The Debug option is described in detail in Appendix C.
Question No. 15 Do you want to use the modified line search and Newton-
Raphson iteration?
The user should answer 'no' to this question for all cases except when
the problem has been run previously and the iteration did not converge. In
such cases the modified line search may be tried. The user should consult
the MINTEQ technical document before using the modified line search.
Questions Nos. 16 through 45:
This series of questions asks for the water analysis data. If
adsorption is not being considered, enter the total dissolved concentration
of all constituents for which water analysis data are available. If
adsorption is being considered, the dissolved plus adsorbed concentrations
should be entered for every constituent for which adsorption parameters are
72
-------
available. The concentration should be in the units chosen in Question 3
and expressed as the chemical formula shown in the question. As examples,
cadmium should be expressed as Cd and boron expressed as ^803. For every
constituent in the water analysis, the program will ask for a guess at the
log of the activity of the component. If you do not make a guess at the
component activity, the model will default to the analytical concentration
divided by 100. Activity guesses are generally important only if model
convergence is a problem. Convergence will generally be a problem with
components such as Fe3+, U+4, U+3, or H3As04, where component activity is
very small in relation to the total mass of the constituent. In such cases,
in oxidizing conditions, a guess of -15.0 to -20.0 will usually work.
Several questions will ask for specific information on each oxidation
state of an element. If only the total concentration of that element is
available and the user wants to consider the other oxidation states, then
the total concentration should be entered as the oxidation state expected to
be dominant and the other oxidation states should be included and assigned a
mass of zero. In such cases remember to enter the appropriate redox
reactions in Question 44.
Question 46: Do you want to consider adsorption?
If you are considering adsorption you will be asked if you want to
consider any of the following five adsorption models:
I. "activity" Kd
2. ion exchange
3. "activity" Langmuir
73
-------
4. constant capacitance model (CCM)
5. triple layer site binding model (TLM)
Regardless of which option is selected, the next question will ask if
two different surface sites will be considered. Different surface sites
will only be important for laboratory experiments using the constant
capacitance and triple layer models or if two different adsorbing substrates
are being considered. An example of the latter case would be when
"activity" Kd values are available for two different size fractions of
suspended material. The majority of the time only one site will be
considered.
"Activity" Kd —
If the "activity" Kd option is selected, the following information must
be provided:
» Reaction ID Number. The first three digits must be 990 or if two
sites are being considered 990 or 991. The next three digits should
be the ID number of the adsorbing component. Component ID numbers
are given in Table 3. The last digit can be any number 0-9.
» Reaction Name. Select any appropriate identifying name. The name
must be Tess than 12 characters.
* "Activity" Kd. This is the distribution coefficient written in terms
of the activity of the component.
74
-------
Next provide the ID numbers for the adsorbing components and the ID for
either surface site one (990) or surface site two (991), if two sites are
being considered. All necessary type changes will be made by the program.
Ion Exchange--
If the ion exchange algorithm is selected, the following information
must be provided:
•» Reaction ID Number. For ion exchange any seven digit number can be
selected which is not already in the data base. It is recommended the
first six digits be the ID numbers for the exchanging components and the
last digit be any number 0-9. This ID selection will insure the number is
not already in the data base.
* Reaction Name. Select any appropriate identifying name. The name
must be less than 12 characters.
e Exchange Constant. Enter the logarithm of the Exchange Constant.
MISP will next ask for the ID numbers for the exchanging components and
their stoichiometries. Remember if a component is on the right side of the
exchange reaction the stoichiometry will be negative.
"Activity" Langmuir Isotherm—
If the "activity" Langmuir isotherm is selected, the following
information must be provided.
75
-------
» Reaction ID Number. The first three digits must be 990 or if two
sites are being considered 990 or 991. The next three digits should
be the ID number for the adsorbing component. The last digit can be
any number 0-9.
• Reaction Name. Select any appropriate identifying name. The name
must be less than 12 characters.
» "Activity" Langmuir Constant. This is the Langmuir constant obtained
by using the activity of the uncomplexed component instead of the
total concentration.
* Total Surface Coverage. This is the total surface sites obtained by
using the activity of the uncomplexed component instead of the total
concentration.
Next provide the ID number for the adsorbing component and the ID
number for either surface site one (990) or surface site two (991). All
necessary type changes will be made by the program.
Constant Capacitance or Triple Layer Models--
Regardless of which of these two models is selected the following
information will be required:
» total surface sites of adsorbent (sites/g)
« guess at the surface potential (PSIO)
76
-------
•» concentration of adsorbent (g/L)
« specific surface area of adsorbent (m2/g)
<•> inner layer capacitance (Farads/m2).
The total surface sites must be expressed in sites/gram. The concentration
of adsorbing solid (suspended solids) must be in grams/liter, specific sur-
face area in square meters per gram, and the capacitance in Farads per
square meter. The necessary experimental or literature data are described
in the MINTEQ technical report. Estimates of the surface potential are
difficult to make but a guess in the range of -0.2 to -4.0 will probably
work. The inner layer capacitance is usually about 1.4.
If the triple layer model is selected the following additional
information must be provided:
» outer layer capacitance (F/m2)
« guess at the potential at the beta plane (XPSIB)
* guess at the potential at the diffuse plane (XPSID)
The outer layer capacitance is normally around 0.2 Farads/square
meter. The guesses at the potentials are difficult to make but -0.2 to -4.0
should normally work.
After providing the necessary adsorption parameters for the constant
capacitance or triple layer models the user must provide information for
each adsorbing species.
n I.D. number
» equilibrium constant
77
-------
* number of reaction components and the stoichiometry and ID for each
component.
The ID number was previously described under activity Kd. The
equilibrium constants and reaction component information must be evaluated
from experimental or literature data. The user is referred to the MINTEQ
technical document for more detailed information on the constant capacitance
and triple layer models.
Question No. 47: Do you want to enter any redox reactions?
Redox reactions relate the activities of two components. If the user
has only a total elemental analysis and wishes to consider the different
oxidation states of the element, the redox reactions between the different
components must be included here. As an example if only an analysis of
total dissolved iron is available and the user wishes to consider both
Fe(II) and Fe(III), then the redox reaction between Fe^+ and Fe^+ must be
included, ID number 2812800. Remember if redox reactions are included all
of the components (i.e., in this example Fe^+ and Fe^+) must be entered in
Questions 16 through 45 and either the Eh must be entered or the electron
included as a component. If redox reactions are included, the program will
ask if new thermodynamic data (i.e., new equilibrium constants or heat of
reaction) are available. The user should answer "No" to these questions
unless more recent and reliable thermodynamic data are available. If new
data are available the user will be queried for the new equilibrium
constants or enthalpy of reaction.
78
-------
Question No. 48: Do you want to include gases at a fixed partial pressure?
The gas phases in the MINTEQ thermodynamic data base are listed in
Table 8.
If the user selects one of these gases the program will ask for the
equilibrium constant modified for the partial pressure of the gas (see the
discussion on Type Modifications). All necessary type changes will be
performed by MISP.
Question No. 49: Do you want any solids to be present regardless of how
much may dissolve?
The solids selected here will be imposed on the aqueous solution and
will modify the solution composition. The model will dissolve or pre-
cipitate as much solid as required to equilibrate the solution. The solid
I.D. numbers are given in the thermodynamic data base of the MINTEQ
technical document.
Question No. 50: Do you want to include solids which are only allowed to
dissolve a specified amount
The solids selected here will only be allowed to dissolve some initial
specified mass plus any mass that may precipitate from solution during the
TABLE 8. GAS PHASES IN MINTEQ
Gas I.D. Number
Methane (CH4) 3301404
Carbon Dioxide (C02) 3301403
Oxygen (0?) 3300023
79
-------
computations. If any solids are selected here the user will be asked to
provide the initial solid concentrations in moles/liter. The user will also
be asked if more recent thermodynamic data such as a new equilibrium
constant or enthalpy of reaction are available. The solid I.D. numbers can
be found in the thermodynamic data base in the MINTEQ technical document.
Question No. 51: Are there any solids that you will allow to precipitate
if they become oversaturated?
This question allows the user to input a list of "considered" (Type V)
solids. If any of these solids become oversaturated MINTEQ will select the
thermodynamically stable phases from the solids listed here and adjust the
solution composition to equilibrium with these solids. Before designating
solids, the user should read the Guidelines for Use Section, Selection of
Solids. If the user has more reliable thermodynamic data, such as a new
equilibrium constant or enthalpy of reaction, for any of these solids these
data can be' entered here. This question will only be asked if a "no"
response was given to Question 13.
Question No. 52: Are there are species you do not want to consider during
the equilibrium computations?
This question is most useful for removing certain Type V solids from
consideration when all solids in the data base are being considered and for
selectively not considering certain aqueous complexes in the geochemical
calculations,, The only other major importance of this question is in
allowing the pE to vary during the precipitation of solid phases. In such
cases the electron must be included as a Type VI species here. For further
80
-------
details on variable pE during precipitation or dissolution of solids consult
the MINTEQ technical manual.
Question No. 53: Do you want to change the equilibrium constant or heat of
reaction for any species in the data base which this
program has not already changed?
This catch-all type question is useful only to users with very specific
problems that cannot be adequately answered in previous questions.
Generally only experienced users of the program will find this question
useful.
Question No. 54: Do you want to add species to the data base for this run
only?
Any species can be added at this point except new components. To add
new components the thermodynamic data files must be modified. If the user
wishes to add species for this run the program will ask for the following
information:
• I.D. number
» reaction name
* enthalpy of reaction
* equilibrium constant (log K)
« minimum log K
o maximum log K
<» species charge
f» Debye-Huckel A and B parameter
* molecular weight
81
-------
r> carbonate alkalinity factor
o stoichiometry and I.D. number for all reaction components.
Only the I.D. number, log K and reaction component information are
absolutely necessary. The carbonate alkalinity factor is valid only for
aqueous species containing carbonate as a component. All of the parameters
listed here are described in the MINTEQ technical document.
There can occasionally be problems in determining species I.D. numbers
for inserted species added here. Appendix C gives a detailed description of
how to determine the correct I.D. numbers.
Question No. 55: Do you want to check your constituent entries?
The information for the components can be printed to allow careful
checking before MINTEQ initiates the geochemical calculations or stores the
data in a file.
INTERPRETATION OF MEXAMS OUTPUT
MEXAMS provides the user with three sets of simulation results:
1) details on metal speciation, sorption and precipitation in each compart-
ment, 2) exposure, fate and persistence predictions for the aquatic system
and 3) a summary of the MINTEQ-EXAMS interactions. The first set of results
are provided by MINTEQ; the second set is provided by EXAMS and the third
set by MISP. The EXAMS users manual and documentation report provides a
detailed description of the EXAMS output. The only change is the addition
of the quantity of precipitated metal to the tables that summarize model
82
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results. This discussion presents the types of output and error messages
generated by MISP and MINTEQ.
The MISP output summarizes the MINTEQ-EXAMS interaction. It contains a
listing of metal concentrations in dissolved adsorbed and precipitated form.
before and after the various MINTEQ updates. This information shows the
effect of each MINTEQ update. The final metal concentrations are printed in
the EXAMS output.
MINTEQ Output
The MINTEQ output is divided into several sections. MISP allows the
user to specify which of these sections MINTEQ will generate for each
compartment MINTEQ solves in the MINTEQ-EXAMS mode. The options available
to- the user and the information contained in each section are described
below. Examples of actual output are provided for reference. The terms
used in the MINTEQ output are defined in Table 9.
If the user selects the linked MINTEQ and EXAMS mode, then MISP will
ask the user for a MINTEQ output option for each compartment. There are
three options:
(1) regular MINTEQ output
(2) print only the distribution of aqueous species and the mass
dissolved, precipitated or adsorbed
(3) print only the mass dissolved, precipitated or adsorbed.
The regular MINTEQ output is described in the following sections. If
the user selected option (1) Sections 1-6 of the following section will be
printed. If option (2) is selected only the percentage distribution of
83
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TABLE 9. DEFINITION OF TERMS USED IN THE MINTEQ OUTPUT
DH - enthalpy of reaction
DHA - Debye Huckel A parameter
DHB - Debye Huckel B parameter
DIFF FXN - the difference between the analytical total and
the sum of all aqeous and adsorbed species
calculated by the model
GAMMA - activity coefficient
GFW - gram formula weight
LOG AP/K - log saturation index
LOG TAP - log ion activity product
NEW log K - equilibrium constant corrected for temperature
and ionic strength
TOTAL MOL - total concentration in molality
Z - species charge
ANAL MOL - total analytical molality
CALC MOL - calculated species molality
components in Section 5 and the mass total summary in Section 6 will be
printed. If option (2) is selected only the mass total summary in Section 6
will be printed.
Section 1--
The first output is of the original sample description file. Certain
explanatory statements are frequently printed here to inform the user of any
changes the model has made to the original sample description. These
84
-------
messages are self explanatory. For example, "H20 HAS BEEN INSERTED AS A
COMPONENT" is always printed. The purpose of this section is to allow the
user to examine the input sample file to check for errors. A listing of the
input sample file is given in Appendix C. The first page of the output for
this section is given in Table 10. A detailed description of Table 10 can
be found in Appendix C.
Section 2—
This section prints the thermodynamic and accessory data for all
species except for default Type VI solids. Default Type VI solids are
printed separately under "SATURATION INDICES FOR ALL MINERALS AND SOLIDS".
The meaning of the column headers is defined in Table 9. The purpose of
this section is to print the initial starting information before MINTEQ
initiates the geochemical calculations. Table 11 is a copy of the first
page of output for this section.
Section 3--
This section provides the initial charge balance information before
aqueous speciation. The sum of cation and anions is printed in mi 11i-
equivalents per liter. A large charge imbalance can be an indication that
one or more major components was not included in the water analysis. How-
ever, occasionally the water analysis will include all necessary components
and the initial charge imbalance will still be large. This commonly occurs
p
when the alkalinity (or HCO^ and CO^") are the dominant anions. The charge
p_
on the entire mass of inorganic carbon is given as minus two since CO^" is
the component. If the inorganic carbon is really all HCO^, this can create
a computational charge imbalance. Therefore, the importance of
85
-------
TABLE 10. SECTION ONE OF THE MINTEQ OUTPUT
•J.50 MS/I-
1 0 0 o i
1 ,r>0 .00
son i
lOQ 1
«lo i
Ibn 1
HO
160
, Pt t
,00 .00
•4,nO
• 5.00
AMU
!jtT
53(5
S.oO
i».pU
• 5,00
3n
23 1
10.00
•B«OW
•4.00
•n,0°
i ' .'J 0 0
-6.
330140?
5 «B
2023100
« 123101
5l23lOn
702310]
Al9500o
5095000
209500{
209500^
209500B
•KOO
.000
.000
• JOQ
•UOU
.000
.900
• 000
.000
.000
• uoo
.000
• 000
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.One
.(JOO
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• O'J
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Reproduced from
best available copy.
86
-------
TABLE 11. SECTION TWO OF THE MINTEQ OUTPUT
CU«|*AU£l«Eu in |Hls HHUSttH
SPpCIt.il
ID
son N*
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H IOIJK nlN i. Ufa*, MAX UOwK
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loooo
• ouoo
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• oooc
• OUOC
• ocoo
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.000
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• OOfl
.000
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• QUO
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2. no
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2.00
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87
-------
any charge imbalance should be interpreted on a case by case basis. An
example of the output for this section is given in Table 12.
Section 4—
This section prints the convergence pattern as the equilibrium problem
is solved. Convergence information is printed only for the first component
the model encounters which has not converged. This information is useful
only to the experienced user of the model who may be interested in obtaining
closer estimates of the component activities to use as initial guesses or is
Interested in analyzing the Newton-Raphson numerical method. An example of
the output for this section is given in Table 13. If convergence is not
reached an error message will be printed.
Section 5—
The next printout will begin with: 'OUTPUT DATA', 'PERCENTAGE
DISTRIBUTION OF COMPONENTS' or 'SATURATION INDICES FOR TYPE 6 SOLIDS'. The
actual order in which these are printed depends upon user input options.
Occasionally there is a K before the name of an aqueous species. This
convention was used in WATEQ3 to distinguish solid phases from aqueous
species and has been retained in MINTEQ for some species. An example is
given for each output group in Tables 14 through 16.
TABLE 12. SECTION THREE Or THE MINTEQ OUTPUT
SUM [IF i*IIUHS» i.ti06»0u;! SUM UP ANlUrtS •
OIFFfcHENCE » i.l
Reproduced from
best available copy.
88
-------
TABLE 13. SECTION FOUR OF THE MINTED OUTPUT
Reproduced from
best available copy.
IrEK K*rii IIJTAU nut uiFf HXN (.Ob Auivn
1 NA 5,22U"U04 «<(.22y"l)04 «'t.0000u
2 r'* S.220-004 1.130-U07
4t 8U1.IU
5UUV£
Mi " ' b.220-OU4 «2'«530-U05
^ (U il220»0y« -b.VSb«007
q rtti r*2B2«007 -fl«4li-OiO
iu4 -e.saj-oo?
Output Data--The following information is printed for species Types I
and II.
ft molality
i activity
« log activity
f activity coefficient (heading GAMMA)
(- log K (modified fo: both ionic strength and temperature)
*. DH (enthalpy of reaction, AH°r)
-------
TABLE 14. SECTION FIVE OF THE MINTED OUTPUT (OUTPUT DATA:
UUTPu'i UAtAI
10 N<
SOfj NA
10o »*
"if! "
15ft CA
5«6 NI
73? SU«
»p, H3BQ3
i?0 r-
5e0 PU«
S*? NUi
«!}» *H<|
3n *U
•Sn <:N
for, cu
7 "2U
9*n "
ANAL MQL
S.22U»00«
7.jad.()07
j.Sai.oob
3.0<"«.OU'4
J>0eb.00ioo
.042
ol?3
.oga
.<><>2
.045
.1U3
.Iti
.OdS
.087
.087
. Ol'S
1
.000
,i)OC
.000
.ouu
.000
.000
.oco
.000
.000
.000
.')00
.000
.ouu
.QUO
.000
.000
.00.0
.000
.000
. 000
Reproduced from &V
best available copy. ^JE
90
-------
TABLE 15. SECTION FIVE OF THE MINTEQ OUTPUT (PERCENTAGE DISTRIBUTION
OF COMPONENTS)
t UlglfUUUUQN UF COMPNNENla
PLKCtNT HUuNU IN 3P£CIt5 » bOJ M
IN SKttits » 100
1UO.O ft^CtNT SQUNO IN SPfeLltS «
-------
TABLE 16. SECTION FIVE OF THE MINTEQ OUTPUT (SATURATION INDICES
FOR ALL MINERALS AND SOLIDS)
SATURATION
In
ALL HINEKAU3 AND
t>00300l
»LUM K
bOflbpOO
2003o01
204boOO
SlUSnOl CALCIfC
2077^01 CHlSTrjoAUiTE
2003n02
2028,01 rt
a!2«iOO rton)?o7CL,j
b 0 2 fa, 0 0 P t g t a (-, 4 j .j
ICj
ft
bOSOfjOO JARUajle,
J*R08Iit
«S!0000
302b,00
50S5003
3026(01
0026^,00
t05000l
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5U2B0ot)
2077003
-J.275
«7,fllO
•T.S4J
•3.334
•1 .013
•11.035
.,208
..Sit.
•5.412
1.32'
-5.561
•3.724
fl.7'52
ii.HT
13.236
•fl.123
•17.9b«
•lo.saa
il.071
•1 .aai
la.oas
•6.291
•S,?1K
•10.326
•3,67«
Jl.333
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-1.969
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-11.467
1.503
4«-486
6°£S5
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5 «0 0 U
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.S.709
6.371
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•12«14£
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MAX UUCiK
•l.Ufl7
3.070
• UCO
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.157
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•.105
•1.155
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•1.131
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•I»451
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7.531
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26.153
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22.UOO
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Reproduced .from
be^ available copy,
92
-------
This information defines the aqueous speciation. The following infor-
mation is then printed for Types III, IV, V and VI species.
» molality
« log K (modified only for temperature)
o DH (enthalpy of reaction)
The molality of a Type III species can be interpreted in different ways
depending upon which category it is in. There are four basic categories:
redox reactions, components at a fixed activity, solid phases and gases at a
fixed partial pressure. The molality of solids and gases has a straight-
forward interpretation. A positive molality indicates the mass of the solid
or gas which precipitated, or was removed, from solution. A negative
molality indicates how much mass dissolved or was added to solution. The
molality of redox reactions or components at a fixed activity has the same
computational meaning but generally lacks any intuitive interpretation,
since a redox reaction cannot have any physical mass.
The molality of a Type IV species corresponds to the amount of the
solid phase present, or precipitated. Type IV species cannot have a
negative mass.
The molality of a Type V species corre-sponds to the saturation index
for that solid.
The molality of a Type VI species can also have a different
interpretation depending upon how the reaction is written. For solid phases
the molality is the saturation index for the solid. The molality of a
Type VI aqueous species is actually the activity of the species. The
activity may not be the same activity which would be computed if the species
were a Type II aqueous complex since Type VI species are not included in the
93
-------
mass balance equations. For gases the molality represents the computed
partial pressure. The molality of Type VI redox reactions generally lacks
any intuitive meaning.
Percentage distribution of components--In this section all species are
printed which comprise greater than one percent of the total analytical mass
for each component. Unfortunately, the percentage distribution may be
meaningless for components which appear on both the right and left side of
mass action expressions such as H+ and h^O.
Saturation indices for Type 6 solids--The following information is
printed in this section:
* SI (saturation index)
•> log K
> minimum log K
Information is printed for all solids in the data base which have all
reaction components present in the input data. The saturation index has
been defined under background information (Section 4). A positive log
saturation index indicates the solid is oversaturated and a negative log SI
indicates the solid is undersaturated. A value of zero indicates
equilibrium with the solid. The log SI may not be exactly zero even when
the solid is in equilibrium. The problem is to determine the appropriate
error band about zero within which equilibrium with the solid is
indicated. The error band for a solid should be evaluated on a case by case
basis since errors in analytical data or aqueous speciation vary from one
water body to another. As a general rule of thumb any log SI within 0.05
times the log K for that solid should be considered as a potential
equilibrium phase (Jenne et al. 1980). However this rule causes the error
94
-------
band to vary depending upon which species are chosen as the components and
upon the number of components in the solid. Care must be exercised in
applying this general rule to all solids because the error band for solids
with large numbers of components can sometimes be as large as three or four
log units. Another useful guideline is to compute saturation indices using
the minimum and maximum log K values, if available. These values are
readily computed from Equation (35).
log SImax = maximum log K + log IAP (35)
The computed log SImax and log SImin can give a good idea of the variabil-
ity in log SI values that could result from errors in the thermodynamic data
for solids.
Section 6—
This section computes and prints a charge balance following aqueous
speciation. This charge balance is more reliable than the initial charge
balance since an aqueous speciation has already been calculated. If the
percent difference between cations and anions is greater than 30 percent
then an important component was probably not analyzed and the calculations
could have significant error.
The total aqueous and adsorbed masses for each component are also
printed. The interpretation of this section is straight forward except when
the component is a Type III species. In such cases the mass of the Type III
species itself, for example H+ ion, is not included in the aqueous mass.
Also the aqueous mass will occasionally be negative for species written on
both the left and right sides of the mass action expressions, for example H+
95
-------
or H20, in such case the aqueous mass is intuitively meaningless. Example
output for this section is given in Table 17.
MINTEQ Error Messages
This section describes the printed error messages, their meaning, and
appropriate responses.
ERROR (1). "COMPONENTS > NXDIM."
The number of components in the sample data file is greater than the
dimensioned array size. The total number of components specified plus any
components that MINTEQ inserts, such as H20, must be less than 30. Correct
this condition by decreasing the number of components. One recommendation
would be to eliminate components such as I", Cs+ or Li+ which do not form
strong aqueous complexes. Another option is to eliminate redox reactions,
and the appropriate components, in cases where one oxidation state is an
unimportant part of the elemental chemistry such as U+3 under oxidizing
conditions. If this error occurs repeatedly the X, Y, Z, IDX and GX arrays
along with the A matrix should be redimensioned which will require modifying
the program.
ERROR (2). "SPECIES > NYDIM".
The total number of species considered in the equilibrium problem
exceeds 400. The most likely cause is the consideration of all the solids
in the data base as possible equilibrium solids. In such cases the number
of Type V species must be reduced. Select the input option that only allows
96
-------
TABLE 17. SECTION SIX OF THE MINTED OUTPUT
r.AMS CO""PARTKEUT IMUC 0
IDX
bOO
100
410
150
4bO
770
20
IdO
732
90
270
5HO
4*2
490
2BO
281
30
SbO
160
600
231
540
140
2 30
1
N A f\ E
it A
o A
K
CA
MG
n4SIu4
AG
CL
S04
H3b03
F
PD4
NQ3
>\H4
FE + 2
FE+3
AL
ZN
CU
Pfl
CU + 2
NI
CO:
H
i.
AvJUEULfa MASS SORBED
b
7
3
3
3
1
9
2
d
4
S
2
1
7
2
1
1
1
1
4
1
1
7
7
0
.220E-U4
. 2 B 2 1 - 0 7
.bblE-05
. 044E-04
.OH5E-04
.417E-04
.272E-07
.793c,-04
.016E-Ob
.626t-0b
. 2b4t-0b
.211E-06
.448E-05
,9B4E-Ob
.bttbE-07
.254E-08
.853E-07
,530£-0b
,b64E-lb
,«27E-07
.574E-06
,703t-06
.2.77E-04
. 378E-04
.OOOE-01
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
e
0
0
0
0
0
0
MASS PRECIPITATED MASS
. OOOE-01
.OOOE-01
. OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
. OOOE-01
.OOOE-ol
. OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
, OOOE-01
.898E-07
, OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
.OOOE-01
, OOOE-01
0
U
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
•
•
*
•
*
•
•
•
*
•
f
*
f
•
t
•
•
t
•
fl
•
t
9
f
•
OOOE-01
000t,-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOb-01
OOOE-01
OOOE-01
OOOE-01
OOOb-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
OOOE-01
H2U
4.179L-Oh
0,OOOE-01
U.OUOE-01
CHARGE BALANCE: SPECIATEU
SUM OF CATIONS = 1.780E-03 SUM OF ANIONS 1.158E-03
PERCENT DIFFt'KEwCE = 2.117E + 01 (ANIUNS - CATIONS)/ C AN IONS •(- CATIONS)
NONCARBOMATE ALKALINITY = 2^904E-Ob
T STRENGTH = : 2.154E-03
consideration of a list of designated solids. Then only include the solids
which have relatively rapid kinetics of precipitation as Type V. If the
number of Type V solids has already been reduced in this manner then the
only way to reduce the number of species is to reduce the number of
97
-------
components. This procedure is described under ERROR 1. Changing a species
type to VI (species not considered) will not reduce the number of species
since the data for these species is also stored in memory.
ERROR (3). "SPECIES NOT FOUND".
This message is preceded by a listing of species not in the data
base. The condition is caused by trying to change the type of a species
which is not in the data base. This is usually a result of entering the
wrong I.D. number for a species, incorrectly formatting the input file or
neglecting to include a component. Recheck the species I.D. number and if
using batch input check the format field specifications given in
Appendix C.
ERROR (4). "CHARGE BALANCE > 30%".
This message indicates that the difference between the summation of
charge for cations and anions in the initial solution is greater than 30%.
This condition is usually caused by poor water analyses or neglecting to
analyze an important component. Water analysis data should be rechecked to
insure a component was not neglected. Since this condition is checked prior
to speciation, the charge balance at convergence could be acceptable. This
usually occurs when such species like CO^- are dominant anions. Since total
inorganic carbon is entered as CO^" all the total carbon is assigned a
charge of -2. After speciation, all total inorganic carbon may actually
exist as as HCO^ with a charge of -1. This in effect creates a
98
-------
computational excess of anions even though the charge balance in the water
sample may actually be within the acceptable limits. In such cases, run
MINTEQ without considering the charge balance criteria. After the program
has finished recheck the final charge balance. If the final charge balance
is still greater than 30% the computations could have significant error.
ERROR (5). "INPUT TYPE > SIX".
A species type has been specified in the sample data file which is
greater than six. This condition is almost always caused by an error in the
sample input format. Check the format fields for inserted species and
species with type changes, Appendix C.
ERROR (6). "PHASE RULE VIOLATION".
MINTEQ computationally eliminates a component for every Type III or
Type IV species. If MINTEQ tries to equilibrate the solution with a solid
phase for which all of the components in the solid dissolution reactions are
already fixed, then the phase rule has been computationally violated. An
example will make this clearer. Suppose solid quartz is already in
equilibrium with the solution, Equation (36).
H4Si04 2 H20 + Si02 (quartz) (36)
This means that all of the components in Equation (36) are computa-
tionally fixed. HpO is fixed by the activity of water expression and the
activity of H4Si04 is fixed by the dissolution of quartz. Now suppose the
99
-------
model also tries to simultaneously equilibrate the solution with chalcedony,
Equation (37).
H20 + Si02 (chalcedony) (37)
A phase rule violation will occur because all of the components in the
chalcedony dissolution reaction are already fixed. To correct the problem a
different list of Type III or IV solids must be entered or one of the solids
the model has "selected", usually the last one selected, should be made
Type VI.
ERROR (7). "ITERATIONS >ITMAX."
The maximum number of iterations has been exceeded. This condition may
occur for a variety of reasons which can generally be grouped into two major
categories. The first category is true nonconvergence. The second category
occurs when the model is approaching an answer but the computations are ter-
minated by the arbitrary selection of the maximum allowable iterations. The
second condition usually occurs as a result of the solid selection process
trying to equilibrate the solution with several solids or as a result of
extremely poor starting estimates for the component activities. In the
latter case the iteration will usually converge if the final computed acti-
vities are entered as the initial guesses and the problem restarted. In the
case of several solids selected during the solid selection process, merely
increase the maximum allowable iterations by selecting the 100 or 200
iteration option in the input. In the case of true nonconvergence the
100
-------
problem is considerably more difficult. In such cases the first suggestion
is to enter low starting guesses for the activities of the nonconverging
components. This can prevent extremely high masses of individual species
occurring in intermediate iterations and thereby causing the activity
coefficients to be reset to one. In other words convergence is generally
easier if you approach convergence from low component activities. This is
particularly true in the case of iron and uranium. Another common problem
occurs when the iterative scheme oscillates between two values. Such
problems frequently occur when polynuclear species are a dominant part of
the total mass. Though these problems are difficult to solve, entering an
intermediate activity for the nonconverging components and using the Newton-
Raphson plus line search numerical method may enhance convergence.
ERROR (8). "SINGULAR Z MATRIX".
A column in the Jacobian matrix has gone to zero. This condition could
happen if the problem is incorrectly defined. For example, setting the
total mass of a component to zero without adjusting the component species
type, such as setting the mass of Fe3+ to zero and not including a redox
reaction between Fe2+ and Fe3+ would cause this error.
ERROR (9). "INVALID COMPONENT".
A component ID number was entered which is not included in the list of
acceptable components stored in the component file (LUN3). Recheck the
101
-------
input sample file to make sure all species ID numbers are correct and are in
the correct format fields.
ERROR (10). "NOT ENOUGH ADS PARAM".
Insufficient adsorption data were entered. This condition only occurs
when using the constant capacitance or triple layer models. The constant
capacitance model requires:
n solid concentration
n specific surface area
o inner layer capacitance
The triple layer model requires all of these parameters plus an outer layer
capacitance. Recheck the sample description file to insure all necessary
information has been entered.
ERROR (11). "A COMPONENT X = 0.0".
The activity of a component has gone to zero. Generally, this cannot
happen unless the problem is incorrectly defined. For example, setting the
mass of Fe + to zero and not including a redox reaction between Fe2+ and
Fe can cause this error. This error can also occur in computers where the
largest exponent the machine can handle is <40. In such cases, the
component can usually be ignored because the activity is very small
(i.e., <1.0 x 10" ), and the solution can be modeled without the component
present.
102
-------
ERROR (12). "AN X APPROACHES ZERO."
The activity of a component is almost zero. The cause and solution are
described in ERROR(ll).
103
-------
SECTION 7
PROGRAMMERS SUPPLEMENT
This section provides the user with information on the structure of
MEXAMS and its three components: MINTEQ, EXAMS and MISP. Each of the
subroutines in MINTEQ and MISP are discussed; the reader is referred to the
EXAMS user manual and documentation report for a discussion of each EXAMS
subroutine. This section also provides details on the modifications made to
the EXAMS code, procedures for the implementation of MEXAMS and a discussion
of resource requirements.
SYSTEM OVERVIEW
MEXAMS consists of three separate programs. One-is a geochemical model
(MINTEQ), one is an aquatic exposure assessment model (EXAMS), and the other
is a user interactive program that links the two models. All three programs
are written in FORTRAN, and are operational on a POP 11/70 computer
system. MINTEQ is also operational on a VAX/VMS 780. However, the VAX
version can only be run in the batch mode. Due to their size, both MINTEQ
104
-------
and MISP had to be overlayed prior to implementation on the POP 11/70. A
direct access file was also needed to store some of the larger arrays.
MEXAMS STRUCTURE
Figure 1 (see Section 5, Description of MEXAMS) shows the overall
structure of MEXAMS. The detailed structure of the individual components,.
MINTEQ, EXAMS and MISP are shown in Figures 2, 3 and 4, respectively.
MEXAMS can be used in one of three modes: MINTEQ only, EXAMS only or
MINTEQ coupled with EXAMS.
EXAMS Only Mode
In the EXAMS only mode MISP transfers the EXAMS input data to the EXAMS
input file FOR005.DAT and EXAMS is initiated with a CALL SPAWN command.
MINTEQ Only Mode
MISP calls subroutine MINIMI to query the user for input data for
MINTEQ. If a MINTEQ input file is already available the program will ask
for the file name. If an input file is not available subroutines MININ1 and
MININ2 will create the file. The procedures for entering data are discussed
in detail in Section 6, Guidelines for Use. If the user elects to model the
data, MISP initiates MINTEQ through a CALL SPAWN command, and sends the data
array IDATA to MINTEQ. IDATA contains flags to let MINTEQ know whether or
not a transport model run will be performed. As soon as MINTEQ receives the
data array, MISP will become inactive (blocked) while waiting for an event
flag to be transferred back from MINTEQ. The command for making MISP
inactive is CALL WAITFR (35).
105
-------
Figure 2, Detailed block diagram for MINTEQ.
106
-------
PRCHEM PRENV
I
DISTRB
FLOWS
CKLOAD
STEADY
I
WATADV
SEDADV
DISPER
PRFLOW
AVEOUT
FLXOUT
DRIVER
PHOTO1 PHOTO2 VOLAT
SUMUP
RKFINT
RKFS
OUTP
Figure 3. Detailed block diagram for the batch version of EXAMS
(taken from the EXAMS users manual and system
documentation report).
-------
Figure 4, Detailed block diagram for MISP.
MINTEQ will now open its sample data file and read in run specific
Information through subroutines INPUT1, INPUT2 and INPUTS. Subroutine
INOUTP prints out the input data. Necessary preliminary calculations are
performed in subroutine PREP. The .equilibrium problem is solved by calling
subroutines SOLID, KCORR, SOLVE and SOLIDX successively. After the
equilibrium probl'em is solved, three entry points in subroutine OUTPUT are
-Tailed: OUTCMP, OUTSPC and OUTPC. OUTCMP prints the component
•information. OUTSPC prints the information for all species types and OUTPC
prints the percentage distribution of components. Finally, subroutine IAP
•;; called "to compute the saturation indices for all Type VI solids.
Once the geochemical simulation is completed, MINTEQ sets the event
•Hag and stops. This is accomplished through the CALL SETEF (35) command.
A-; this point, MISP becomes active again. This completes a single MINTEQ
; un.
108
-------
MINTEQ Coupled with EXAMS Mode
MISP calls subroutine INFILE to query the user about MINTEQ input files
and the number of times metals concentrations will be updated with MINTEQ.
MINIMI creates the MINTEQ input file MINTEQ.INP. When both EXAMS and MINTEQ
input files are ready and closed, MISP subroutine XAMINP initiates EXAMS
through a CALL SPAWN command and calls XAMINP, waits for EXAMS to return,
processes EXAMS predicted metal, sediment and biomass concentrations to send
to MINTEQ, and calls subroutine MINRUN. MINRUN initiates MINTEQ through a
CALL SPAWN command and begins accumulating MINTEQ simulation results for
EXAMS. The MINRUN-MINTEQ interaction continues until all of the EXAMS metal
results have been updated, then MINRUN returns to XAMINP. XAMINP send EXAMS
the accumulated results from MIMTEQ. The EXAMS-MINTEQ processs continues
for as many times as the user initially requested. Then EXAMS finishes the
run, sends a flag to XAMINP signalling the end of the run, and stops.
MINRUN sends MINTEQ a flag signalling the end of the run, and MINTEQ
stops. Then MISP stops.
DESCRIPTION OF MEXAMS ROUTINES
The following provides a detailed description of each of the
subroutines in MISP and MINTEQ. The user is referred to the EXAMS users
manual and system documentation report for a similar description of EXAMS
subroutines. Many of the variable and subroutine names in MINTEQ were
retained from either WATEQ3 or MINEQL to assist users of these codes.
109
-------
MISP Subroutines
MISP queries the user for the simulation mode to be used (MINTEQ only,
EXAMS only or EXAMS-MINTEQ). If MINTEQ only is selected, MISP calls
subroutine MINIMI and then invokes MINTEQ. If EXAMS only is selected MISP
invokes EXAMS. If EXAMS-MINTEQ is selected, MISP calls subroutines INFILE,
MININ1, invokes EXAMS, and then calls XAMINP.
Subroutines MINIMI and MININ2--
Subroutines MINIMI and MININ2 displays questions on the user's
terminal, processes the user's answers and create an input file for MINTEQ.
Subroutine MINRUN--
Subroutine MINRUN controls the MINTEQ-MISP interactions and manipulates
the data being passed to MINTEQ. The inter-program file PASS.DAT is used
between MISP and MINTEQ.
Subroutine INFILE—
Subroutine INFILE queries the user for the MINTEQ input file(s) and the
number of EXAMS-MINTEQ interactions.
Subroutine XAMINP--
Subroutine XAMINP controls the EXAMS-MISP interactions and manipulates
the data returned from EXAMS. The inter-program file TRANSF.DAT is used
between MISP and EXAMS.
110
-------
MINTEQ Subroutines
This section contains a detailed description of the MINTEQ sub-
routines. A description of the important variables and arrays used in
MINTEQ is given in Table 18. A listing of the program is given in
Appendix A.
Subroutine ACTVTY--
Subroutine ACTVTY computes all activity coefficients and corrects the
equilibrium constants by calling subroutine KCORR.
The first section of the subroutine computes the concentration of
aqueous complexes using the activities just computed on a given iteration
and the equilibrium constants from the previous iteration. This gives
improved values for the ionic strength used in computing activity coeffi-
cients. The loop on 100 computes the ionic strength.
If the computed ionic strength exceeds 4.0 molal, the next section of
the subroutine sets the ionic strength to an initial starting estimate^3' to
prevent large fluctuations in the activity coefficients at intermediate
iterations. The loop on 110 computes activity coefficients using the Davies
equation. The loop on 150 initializes all activity coefficients for neutral
species to 0.1 times the ionic strength. The loop on 120 computes activity
coefficients using the extended Debye-Huckel equation for all species with
non-zero ion size parameters. If the debug option has been set to one, the
values of the IDX, X, IDY, GAMMA, C and Y arrays are printed at each
iteration.
(a) The initial starting estimate is simply one half the sum of the analytical
molality times the charge squared for all components.
Ill
-------
TABLE 18. DESCRIPTION OF IMPORTANT VARIABLES AND ARRAYS USED IN MINTEQ
Parameters
NXDIM
NYDIM
ITMAX
ITER
EPS
NNN
TEMP
FLAG
TEMPK
R
VHC
VH
CORALK
IDEBUG
KOUNT
AA
BB
DENS
MU
MUHALF
NONCRB
MAXSIZ
ICHARG
LUNO
LUN1
LUN2
LUN3
LUN4
LUN5
LUN6
Dimension of the X arrays
Dimension of the Y arrays
Maximum number of iterations allowed; this value can be adjusted
in input
Iteration counter
Convergence criteria
The number of components
Water temperature in degrees Celcius
Units of input
Temperature in degrees Kelvin
Ideal gas constant
Conversion factor for log-|g-Naperian log
Van't Hoff correction term
Alkalinity input option
Debug printing option
The number of inserted species or species with type changes not in
main memory
Debye-Huckel A parameter
Debye-Huckel B parameter
Density of water
Computed ionic strength
Square root of MU
Noncarbonate alkalinity
Parameter to contol the maximum word size
Input parameter to allow skipping charge balance criteria
Logical unit number for output file
Logical unit number for input sample file
Logical unit number for thermodynamic data file for default
species types (2-6)
Logical unit number for component data file
Logical unit number for type 6 solids file
Logical unit number for noncarbonate alkalinity file
Logical unit number for the file containing the coefficients of
the temperature dependence of log K with temperature.
112
-------
TABLE 18. (contd)
Arrays
GX Log of the component activity
X Activity of component
T Total analytical concentration
Y Value of the difference function
Z Jacobian matrix
C Species concentration
GC Log of species concentration
GK Log of the equilibrium constant
A Stoichiometry matrix
IDX Component I.D. numbers
IDY Species I.D. numbers
SPCZ Species Charge
DHA Debye Huckel ion size parameters
DHB Debye Huckel ion size parameters
GFW Specie gram formula weight
DH Enthalpy of reaction (%H°r ^gg)
IDYDUM ID numbers of inserted spedies or species with type changes which
are not in file LUN2
MINGK Minimum value of the equilibrium constant
MAXGK Maximum value of the equilibrium constant
NAME Alphanumeric name of the species
NN The number of species types one through six
GAMMA LogiQ of the species activity coefficient
ALKFCT Carbonate alkalinity factor
Subroutine ADD--
Subroutine ADD initializes all variables and arrays. The subroutine
was pulled out of subroutine MAIN to allow MINTEQ to be overlayed on the
POP 11/70. Subroutine ADD is included in subroutine MAIN in the VAX version
of MINTEQ.
Subroutine ADSORB--
Subroutine ADSORB consists of three entry points ADSID, ADINIT, and
ADSJAC. All three entry points are called from subroutine SOLVE.
113
-------
Subroutine ADSORB is only used if the constant capacitance model or triple
layer site binding model are used.
Entry ADSID initializes some useful adsorption constants and locates
the column numbers for adsorption components. Entry ADINIT computes the
potential and the total charge at the various planes from the capacitances
and potentials. Entry ADSJAC modifies the Jacobian matrix as described in
the MINTEQ technical report.
Subroutine ALKCOR--
This subroutine converts the input value of the alkalinity measured in
terms of equivalents into a mass of total inorganic carbon expressed as the
ity of COj".
The loop on 10 computes the excess equivalents of H+ ion consumed by
molality of COj"
one
mole of a carbonate containing species over the stoichiometry of carbonate
in the species. The loop on 200 reads the noncarbonate alkalinity file on
the first iteration only. The loop on 400 sums the equivalents of noncar-
bonate alkalinity. The next section computes the mass of carbonate. If the
computed mass of carbonate is negative the mass is set to the input alka-
linity times two. There are debug prints in both the carbonate and non-
carbonate alkalinity routines.
Subroutine CONVRG—
Subroutine CONVRG modifies the Newton-Raphson corretion terms using a
modified line search technique. The subroutine uses past iteration points
to help predict new values of the unknown activities. The purpose of the
114
-------
line search is to estimate values of the unknowns that are close enough to
the true answer to allow Newton-Raphson to converge. When the mass balance
criteria are satisfied within 50%, the line search is stopped. The data
points for the current and previous iterations are stored in the P matrix.
The method is described in detail in the MINTEQ technical document.
Subroutine ERROR and ERROR2--
Subroutine ERROR is called only when a fatal error occurs in the
program. An error message is written to LUNO, followed by component and
other species information for the current iteration. Then MINTEQ stops
execution. Subroutine ERROR2 was added only to facilitate the POP 11/70
overlay.
Subroutine EXCOL--
This subroutine merely exchange the columns JO and JJ passed from
subroutine SOLID. Columns JO and JJ of the IDX, X, GX and T arrays are
exchanged along with the corresponding columns of the A matrix.
Subroutines EXROW and EXRO--
These subroutines exchanges rows 10 and II passed from subroutines
INPUT, SOLIDX or SWITCH. Rows 10 and II are exchanged in the following
arrays: IDY, C, GK, DHA, DHB, GFW, SPCZ, DH, NAME, MINGK, MAXGK, and
GAMMA. Rows 10 and II are also exchanged in the A matrix. Subroutine EXRO
was added only to facilitate the POP 11/70 overlay and is not included on
the VAX version.
115
-------
Subroutine EXMLK--
This subroutine reads and writes data to file PASS.DAT which is also
accessed by MISP. The subroutine has three external entry points, EXMLK1,
EXMLK2, and EXMLK3.
EXMLK1 reads the input file PASS.DAT if MISP is in the MINTEQ-EXAMS
mode. The following information is read from PASS.DAT.
» MINTEQ output option for this compartment (IOUT),
« The component ID for the metal being followed (ICIDX),
» The aqueous plus adsorbed mass of metal (AQMASS),
A The sediment concentration in mg/£ (SEDCON),
n The concentration of biota in mg/£ (BIOCON),
» The number of precipitated solids (IPRCPT),
<» The ID number for each solid (IPIDY) and the mass of each solid in
moles/£ (PRECIP).
EXMLK2 initializes the appropriate arrays with the information read in
EXMLK1.
EXMLK3 computes the necessary information to pass back to MISP- The
following data is written to file PASS.DAT.
n The total mass of metal adsorbed onto biota (BV),
« The total mass of metal adsorbed on sediments (SV),
* The dissolved concentration of metal (V),
« The ID number for each precipitated solid (IDY),
116
-------
« The mass of each precipitated solid (C),
» Conversion factor for each solid from moles/2, to mg/£ (CF).
Functions IADX and IADY —
Function IADX finds the column number for component IDXT. Function
IADY finds the row number for species IDYT.
Subroutine IAP--
Subroutine IAP computes the saturation indices for all solids in the
Type VI solids file. The loop on 120 computes the ion activity products and
the saturation indices. The loop on 130 checks to insure inserted species
(see Appendix C) were not Type VI solids. If an inserted species has the
same ID number as a Type VI solid then two asterisks are printed immediately
before the data for that solid to indicate the inserted species is already
in the data base.
Subroutine INOUTP--
Subroutine INOUTP is called from MAIN immediately after SUBROUTINE
INPUTS. INOUTP prints the initial input data for all species types. This
subroutine is included in subroutine OUTPUT on the VAX version of MINTEQ.
Subroutine INPUT1 —
Subroutine INPUT1 reads the run specific information needed to set up
the equilibrium problem. The sample description file (LUN1) is read first.
117
-------
Beginning with preliminary information, such as sample description, tempera-
ture and various program options. The Van't Hoff correction term is set
equal to:
VH - (298.16 - TEMPK)/(298.16 x TEMPK X VHC X R) (38)
Van't Hoff temperature correction of Equilibrium constants is explained in
the MINTEQ technical document. The loop on 10 brings in the component
information. The next section inserts the H20 and dissolved sulfur S(0)
components. S(0) is only inserted if component HS is included and the user
does not have analytical data for S(0). The loop on 205 insures all
components are valid. Once the component is found in file LUN3 the loop on
200 fills out the appropriate arrays.
Subroutine INPUT2--
Subroutine INPUT2 reads thermodynamic data for species Types II through
VI from file LUN2. The Type VI species in this file are not solids. The
loop on 400 sets the species types. The loop on 340 inputs the thermo-
dynamic data and the loop on 300 checks to see if all of the components for
that species are present before the data are stored in memory.
The next block of code reads species modifications and type changes
from file LUN1. A search is begun to find the species and the previous
species type. When the species is found, a call to subroutine SWITCH
changes species types. The loop on 710 searches memory. If the species is
not found in memory the necessary information is stored in local arrays
until all type changes have been read from file LUN1. The Type VI solids
118
-------
file is then searched for the species not found in memory. If these species
are not found in the Type VI solids file, an error message is printed and
the program terminates.
Subroutine INPUT3--
Subroutine INPUTS allows insertion of species not in the thermodynamic
data base. The loop on 990 performs the species inserts. The loop on 993
checks to insure all of the components for the inserted species are in
memory. The loop on 600 .searches main memory to insure the species is not
already in the data base. If the species is found in memory; a message is
printed and the species is ignored. Otherwise the ID number is stored in
array IDYDUM which will be checked in subroutine IAP to insure the inserted
species was not a Type VI solid. Subroutines INPUT1, INPUT2, and INPUTS are
combined in subroutine INPUT in the VAX version of MINTEQ.
The next section of code changes S(0) and h^O to Type III species if
S(0) was not an analytical input.
Subroutine KCORR--
Subroutine KCORR modifies the equilibrium constants for ionic strength
for Types I and II species. The equilibrium constants are modified by,
log Ki = log Kn- - log y^Sg)
where Y-J is the activity coefficient for species i and K-J is the equilibrium
constant for species i. Since the ionic strength may vary during the itera-
tive procedure, the log K-j in Equation (39) must be reset to the values at
119
-------
infinite dilution every iteration. This is done in the loop on 200. The
entry KCORR2 is called from subroutine MAIN to reset the infinite dilution
log iq terms every time the log K, terms are modified for solids. Debug
option 3 in KCORR2 prints the values for NNN, NN(1), NN(2), and the IDY,GK
and GK1 arrays.
Subroutine OUTPUT—
Subroutine OUTPUT has three entry points. These entry points are
OUTCMP, OUTSPC and OUTPC. They are called from various subroutines. OUTCMP
prints component data for such parameters as activity, concentration, and
the activity coefficients during the iterative process. This entry is
called from subroutines ERROR and SOLIDX and from the MAIN program. Entry
OUTSPC prints information for all species at .various times during the SOLID-
SOLIDX loop in MAIN. The output information is different for the various
species types. The different output was selected to minimize confusion to
the user. OUTPC performs several functions. The loop on 110 calculates and
prints the percentage distribution of components. All species which com-
prise greater than 1% of the analytical mass of the component are printed.
If a different tolerance is desired reset THRSH in subroutine MAIN. The
loop on 180 computes the aqueous and adsorbed masses. For this routine to
work the ID numbers for sorbed species must be greater than 9900000. The
mass of Type III aqueous species such as H+ ion are not included in the
computed aqueous mass. The loops on 200 and 230'compute the final charge
balance. The loop on 900 prints the values of the IDX, IDY, X, C, and Gamma
arrays if debug option one is selected.
120
-------
Subroutine PREP--
Subroutine PREP performs a series of preliminary calculations to setup
the equilibrium problem. The loop on 100 corrects all equilibrium constants
for temperature using the Van't Hoff relation by calling function VHOFF.
The loop on 660 reads in the coefficients for the analytical expressions of
log K with temperature. The loop on 680 then modifies the equilibrium
constants using the analytical expressions. The analytical expressions for
log K with temperature are described in the MINTED. technical document. The
next section of code computes the Debye-Huckel A and B parameters as a
function of temperature. This section of code was translated directly from
WATEQ2 (Ball et al. 1979) as documented in Truesdell and Jones (1974). The
next section of code converts all analytical units to molality. The loop on
150 initializes the X and GX arrays to the total mass divided by 100 for
components with no activity guess.
The activity of water is set by modifying the equilibrium constant,
GKwater = -Io9 U'0 - °'017 x CC1)
where CC1 is the summation of the analytical molality of all components.
The loop on 160 computes a cation/anion balance. An error message is
generated if the imbalance exceeds 30%. The final part of subroutine PREP
prints the IDX, IDY, NAME, X and C arrays if debug option one is selected.
121
-------
Subroutine SIMQ--
Subroutine SIMQ is identical to subroutine SIMQ in MINEQL. The
Jacobian matrix is solved by gaussian elimination and back substitution
The Y array is modified as follows:
where n is the iteration number. The new values of the activities at the
new iteration (xn + -'-) are then recomputed in subroutine SOLVE.
Subroutine SOLID--
Subroutine SOLID modifies the T and GK arrays and the A matrix for the
presence of Type III and IV species. The mathematics is described by
Westall et al . (1976). Subroutine SOLID is identical -to subroutine SOLID in
MINEQL except for the debug print. If debug option four is selected, the
values of the IDX, X, IDY, C and GK arrays are printed.
Subroutine SOLIDX--
Subroutine SOLIDX unmodifies the T, X, GX and GK arrays for the
presence of solids, computes the amounts of solids and selects the
thermodynamically stable solids. The loops on 460 compute the mass of
solids and unmodifies the arrays. The mathematics is described by Westall
et al. (1976). The loop on 210 computes the saturation indices for Type V
and VI species. The loop on 770 is a debug print which is identical to the
debug routine in subrountine SOLID.
122
-------
The next section of code embodies the solid selection routines
described in Section 4 of the MINTEQ technical report . Solids are checked
first for dissolution, if the mass of any Type IV species is negative the
solid is dissolved by switching the species type to V. Control is then
passed to subroutine MAIN. If no solids have dissolved the solids are
checked for precipitation. If solids are oversaturated then the highest
ranked solid is precipitated by switching the species type to IV. The loops
on 300 and 320 allow user designated output at various points in the solid
selection process.
Subroutine SOLVE--
Subroutine SOLVE solves the chemical equilibrium problem created by
SOLID and SOLIDX. The loops on 2 and 3 compute the.concentration of all
aqueous complexes. Next subroutine ALKCOR is called if alkalinity was input
and entry ADINIT is called if the constant capacitance or triple layer
adsorption models are being used. The loop on 201 resets the Y array to:
m
Y = - T + y a(i,j)C
J J i=1 i
where Yj is the difference function for component j, Tj is the analytical
mass for component j, m is the number of aqueous species, C-j is the
concentration of species i, a(i,j) is the stoichiometry of component j in
species i, (-see Section 4 of the MINTEQ technical report. The loop on 300
computes the Jacobian matrix. Next, ADSJAC is called to modify the Jacobian
if the constant capacitance or triple layer adsorption models are being
used. Statement 811 checks for convergence. If the problem has not
123
-------
converged a new iteration is begun. Subroutine SIMQ is called and the
difference between the new activities and the old activities is passed back
in the Y array. New values for the acti vities are computed and the
equilibrium constants are corrected for ionic strength by calling ACTVTY.
When a new iteration is begun the data for the previous iteration is
printed.
Subroutines SWITCH and SWICH—
Subroutine SWITCH changes species types. Species I is moved from
Type L (the previous type) to LTYPE (the new type). This subroutine was
originally part of subroutine INPUT in MINEQL. It was made a separate
subroutine because of the number of places it must be accessed in MINTEQ.
Subroutine SWICH is identical to subroutine SWITCH. SWICH was created to
facilitate the POP 11/70 overlay.
Function VHOFF —
Function VHOFF corrects the equilibrium constants for temperature by
Equation (42),
Log KT = log K2% - AH°2g8 * VH (42)
where VH has been initialized as described in subroutine INPUT, K is the
equilibrium constant and AH° iu , •,
dlu flnr is the enthalpy of reaction. Function VHOFF is
accessed from subroutines PREP and IAP.
124
-------
EXAMS CODE MODIFICATIONS
As was discussed in Section 6, Guidelines for Use, several modifica-
tions were made to the batch version of EXAMS. None of these modifications
affect the use of EXAMS for the analysis of organics. The modified sub-
routines are shown in Figure 5. They are DATAIN, GHOST, DISTRB, DISPER,
FIRORD, AVEOUT, DRIVER, RKFINT, RKFS, STFINT, STIFF, and OUTP. The main
changes made to each subroutine are discussed below.
Common- PART1L
«» Dimension of the variable, ALPHA was changed from ALPHA (18,010) to
ALPHA (19,010)
*
n The new variable, KFLAG, was added to the transfer list from MISP to
EXAMS. KFLAG is the number of times MINTED, will be used to update the
"steady-state" computation performed by EXAMS.
* The new variable, LFLAG was added to transfer from MISP to EXAMS the
number of times MINTEQ will be used to update the "persistence"
computations performed by EXAMS.
<» The new variable, LCNT, was added as a timestep counter for the
''persistence" computation.
« The new variable KCNT was added as a loop counter for the "steady-
state" computation.
125
-------
1 1 1
PRCHEM PRENV ;DISTRB
'-XXXXXXX
1 1
WATADV SEDADV %D\
;DATAIN;
; GHOST;
BLOCK
INREC
.^J '
xl 11 1 J/^xx/'/-^'<4
3 FLOWS CKLOAD KFIRORDJ
A I | 1 f/x/xxxxxxl
1 1
SPER| PR FLOW]
'//////A \
\
PHOTO 1 JPHOTO2
1
STEADY
1
VOL AT
f
} '
'XXXXXXXXxl 1
AVEOUTJ FLXOUT
'X/X/XXXXx! 1
1
rxxxx 'xxx,l I
pDRIVERl SUMUP
{^xxxxxxxxl 1
FCT
_L
G1NTRP
FCT
1
GEAR
J.
DECOMP
FCT
FDER
Figure 5. Detailed block diagram for the batch version of EXAMS showing
the subroutines that were modified (cross hatched).
-------
Common RESULT
n Dimension of the variable Z was changed from Z(18) to 1(21}.
Common RESIT
n Dimensions of the variables DOMAX, MAXPT, DOMIN, MINPT were changed
from DOMAX(IO) to DOMAX(12),
from MAXPT(IO) to MAXPT(12),
from DOMIN(IO) to DOMIN(12),
from MINPT(IO) to MINPT(12).
Subroutine DATAIN
n The variable, KCNT, was initialized to be zero
KCNT = 0
*» The variable, LCNT, was initialized to be zero
LCNT = 0
<•> After all the computations are completed in EXAMS or errors in input
data are discovered by EXAMS, subroutine DATAIN sends the following
signal to inform MISP that the EXAMS simulation has been completed:
CALL SETEF(39,IDS)
127
-------
Subroutine GHOST
9 Sends a signal to MISP that EXAMS is ready to accept metal
concentrations updated by MINTEQ:
CALL SETEF(37,IDS)
CALL WAITFR (38,IDS)
CALL CLREF(38,IDS)
<* Receives KFLAG from MISP. Depending on the value of KFLAG, the
following variables for all the compartments will be provided by MISP
to EXAMS:
ALPHA(16,J), ALPHA(17,J), ALPHA(18,J), and ALPHA(19,J),
where J is the compartment number.
Note that these four values correspond to the fraction of precipitated,
dissolved, sediment-sorbed and bio-sorbed metal in each compartment.
This process will be repeated in GHOST until all of the metal fractions
required for the steady state computations have been updated by MINTEQ
values.
_Subrouti ne OISTRB
« Since the modified EXAMS includes precipitation, the size of the ALPHA
array was changed. This change in dimension required some adjustments
such as
128
-------
DO 210 I = 17,19
ALPHA(I.J) = 0
Kl = 1-16
K2 = 1-3
DO 200 K = K1,K2,3
ALPHA(I.J) = ALPHA(I.J) + ALPHA(K,J)
200 CONTINUE
210 CONTINUE
Subroutine DISPER
Similar to Subroutine DISTRB, the dimension change of the ALPHA array
made adjustments to the program necessary.
The main change in this subroutine was to replace ALPHA(17,J) by
ALPHA(16,J) + ALPHA(18,J). This substitution is based on the
assumption that the precipitated metal is transported with the sediment
in compartment J. This change includes the metal dispersion
computation as follows:
SEDFL(KK,K3) = SEDFL(KK,K3) + TEMSED
*[ALPHA(17,K3)*SEDCOL(K3)]/[ALPHA(16,K3) + ALPHA(18,K3)]
*[ALPHA(16,KK) + ALPHA(18,KK)]/[ALPHA(17,KK)*SEDCOl(KK)]
129
-------
Subroutine FIRORD
*» Adjust ALPHA array references to reflect the change in dimensions such
as
TEMP3 = ALPHA(17,J)*100
instead of
TEMPS =ALPHA(16,J)*100
* Change EXPOKL, INTOUL, INTINL and TEMPS to include both sediment-sorbed
and precipitated metals as sediment resident quantities. For example,
EXPOKL(J) = WATOUL(J)*ALPHA(17,J) + SEDOUL(J)
*[ALPHA(16,J) + ALPHA(18,J)]/SEDCOL(J) + WATOUL(J)
*ALPHA(19,J)*PLRAG(J)
INTOUL(J) - INTOUL(J) + WATFL(I,J)*ALPHA(17,J)
+ SEDFL(I,J)*[ALPHA(16,J) + ALPHA(18,J)]/SEDCOL(J)
+ WATFL(I,J)*ALPHA(19,J)*PLRAG(J)
Subroutine AVEOUT
« Adjust ALPHA array references to reflect the change in dimensions.
•» Adjust the size of the Z array to accomodate additional precipitated
130
-------
metal concentration values. This leads to many additions and changes,
includi ng,
1(2) = 1(2) + ALPHA(18,J)*Y(J)/SEDCOL(J)
1(20) = Z(20) + ALPHA(16,J)*Y(J)
» Add a calculation of the average, maximum and minimum precipitated
metal concentrations
* Add the number of total compartments, KOUNT; the sum of computed
steady-state dissolved, sediment-sorbed, and biosorbed metal
concentrations, SPECON; precipitated metal concentrations, PRECON;
sediment concentration, SEDCON(J); and the biomass concentration,
BIOCON(J) for all compartments in the file "TRNSF.DAT" in Logical
Unit 11. This file will then be read by MISP to supply these
concentrations to MINTEQ to update ALPHA values.
Subroutine DRIVER
« Remove equivalence statement with W array.
« Remove variables, KOUNT, TFINAL, TINCR, T, IFLAG and TPRINT from
arguments at Subroutines RKFINT and STFINT because these variables are
in COMMON storage areas SETUPG and TIMEL which were added to Subroutine
RKFINT and STFINT.
131
-------
Subroutine RKFINT
» Remove varibles KOUNT, TFINAL, TINCR, T, JFLAG and IPRINT from the
argument list.
« Include 'GLOBAL.COM', 'CHEML.COM1 and 'ENVIRL.COM1.
*> Similar to the steady state case performed in Subroutine GHOST, this
subroutine sends signals to MISP to receive metal concentrations
updated by MINTEQ for the persistence computation. This involves:
- determining if MISP/MINTEQ must be called or not,
- sending signals to inform MISP that EXAMS is ready to read data
from MISP
- reading KFLAG and LFLAG. Depending on LFLAG and LCNT, reading
ALPHA values for all compartments updated by MINTEQ from MISP
through file "TRNSF.DAT" in Logical Unit 11.
READ(11,103) [ALPHA(I.J), 1=16,19), J=l,KOUNT]
n After new ALPHA values are read from MISP/MINTEQ, RKFINT updates the
INTINL value based on new ALPHA values for all compartments:
INTINL(I.J) = WATFL(J,I)*ALPHA(17,I)
+ SEDFL(J,I)*[ALPHA(16,I) + ALPHA(18,I)]/SEDCOL(I)
+ WATFL(J,I)*ALPHA(19,I)*PLRAG(I)/WATVOL(J)
132
-------
«» The update of ALPHA and INTINL for the persistence computation will be
repeated a number of times preassigned by the user.
» Send signals to MISP and receives updated fractions of dissolved,
sediment-sorbed, biosorbed and precipitated metal for the persistence
computation.
Subroutine STFINT
« Modifications made in this subroutine are the same as those in
Subroutine RKFINT.
Subroutine OUTP
Modifications made in this subroutine are similar to those in
Subroutine AVEOUT.
« Adjust ALPHA
<* Write KNTDUM,J,ALPHA in file "TRNSF.DAT" in Logical Unit 11 for
MISP/MINTEQ to read.
« Send a signal to MISP when the persistence computation is completed.
MINTEQ SUPPORTING DATA FILES
MINTEQ has five supporting data files. The data files are assigned
logical unit numbers in the main program.
133
-------
File LUN1
This file contains a description of the water analyses and other run
specific information. File LUN1 is described in detail in Appendix C.
File LUN2 - Default Thermodynamic Data
File LUN2 contains thermodynamic and accessory data for all species
types except components and Type VI solids. The data are arranged in such a
manner that as they are read into memory a specific type is automatically
assigned. The first group of data is for aqueous complexes of Type II.
MINTEQ detects the end of Type II species by reading two blank lines. Since
there are no default Type III or IV species, the next four lines are
blank. The next group of data is for Type V species. It is also terminated
with two blank lines. The last group of data is for default Type VI
species. The file terminates with two blank lines.
Species types are separated by two blank lines and there are two lines
of data for each species. Line one has format (I75 1XS M2, 2F10.4, 2F8.3,
3F5.2, F9.4) and the format fields correspond to the species ID number,
name, enthalpy of reaction, equilibrium constant, minimum equilibrium
constant, maximum equilibrium constant, charge, Debye-Huckel A, Debye-
Huckel B, and gram formula weight. Line two has format. [F 5.2, IX, II, 3X,
8(F7.3, IX, 13, 3X)] and the format fields correspond to the: alkalinity
factor, number of components in the reaction, stoichiometry of component n
and ID number of component n.
134
-------
File LUN3 - Component Data File
File LUN3 contains the necessary data for the components. Each
component has only one line of data in format (13, IX, 2A4, F4.1, 4X, F5.2,
8X, F11.5). The format fields correspond to the ID number, name, charge,
Debye-Huckel A, Debye-Huckel B, and the gram formula weight. There must be
a blank line at the end of the file. This file must be modified every time
a new component is added.
File LUN4 - Type VI Solids File
This file contains the thermodynamic and accessory data for all solid
phases in the data base. By storing the solids data in both files LUN2 and
LUN4 it is easy to allow the solids to default to either Type V or VI.
Also, if the solids default to Type VI, file LUN4 eliminates the need to
•
store all solids data in memory whea it will only be needed at the very end
of the program.
File LUN4 contains two lines of data for every solid phase. There must
be two blank lines at the end of the file to prevent an end of file con-
dition. The format fields for each line of data are identical to file LUN2.
File LUN5 - Noncarbonate Alkalinity
This file contains the noncarbonate alkalinity information. The
selected noncarbonate alkalinity species were taken from the WATEQ3 code
(Ball et al. 1981). To add or delete species considered in the noncarbonate
alkalinity calculations requires modifying this file.
File LUN5 contains one line of data for each species which consists of
the species ID number and the noncarbonate alkalinity factor. There must be
135
-------
one blank line at the end of the file. File LUN5 is reproduced in
Table 19. The species name is provided only for information and is not
included in file LUN5.
File LUN6 - Analytical Expression File
File LUN6 contains the coefficients for the analytical expressions of
log K with temperature. The coefficients A through G are for the following
generalized expression:
Iog10 K(T) = A + B-T + C/T + D * Iog10 T + E«T2 + F/T2 + G/ /T .
MINTEQ DATA STORAGE STRUCTURE
The data storage system is very simple. All major arrays are related
•
to the rows or columns of the A (stoichiometry matrix). Information for
components is stored in arrays which correspond to the columns of the A
TABLE 19. NONCARBONATE ALKALINITY SPECIES
ID
Number
0303302
3307701
3307700
3300900
3305800
3307301
3300000
580
730
Name
Al (OH1-
H2SiOf
HoSi OA
HoBQo
HPO?
S
OH:
por
HS
Noncarbonate
Alkalinity
Factor
1.00
2.00
1.00
1.00
1.00
2.00
1.00
2.00
1.00
136
-------
matrix. Information for all species types is stored in arrays which corre-
spond to the rows of the A matrix. Figure 6 presents a schematic visuali-
zation. The array names are defined in Table 18.
MINTEQ divides the rows and columns into blocks. The rows are divided
into six blocks; one block for each species type. The NN array contains the
number of species in each block. The columns are divided into two blocks.
The first block contains components with a mass total. The second block
contains components with an established fixed activity relationship as a
result of modification for the presence of Type III or IV species.
1234 (COLUMN NUMBERS)
c
tr
IDY
SP
SPCDHB ALKFCT
CDHA SPCGFW
GK
W
INGK
MAXGK
•
DH
N
Y
T
GX
X
GAMMA IDX
AME SPCZ
A
MATRIX
-•— NXDIM — >-
NY
)IM
'
Figure 6. Visualization of data storage structure,
137
-------
MEXAMS IMPLEMENTATION PROCEDURE
All files needed to implement MEXAMS on a POP 11/70 will be on a
1600 bpi magnetic tape with a VOLUME-ID of MEXAMS. The standard PDS copy
command will be used to put the files on the tape. The following files will
be needed:
For MISP:
1. MISPF4P.CMD - for FORTRAN compilation
2. MISPLNK.CMD - to create MISP
3. MISP.FTN - driver program
4. Six subroutines - listed in the discussion entitled DESCRIPTION OF
MEXAMS ROUTINES
5. MISP.CMN - MISP common block
6. XAMINP.CMN - common block
7. MININP.CMN - common block
8. MISP.DDL - MISP overlay.
For MINTEQ:
1. MINTEQF4P.CMD - for FORTRAN compilation of 23 MINTEQ routines
2. MINTEQLNK.CMD - to create MINTEQ.TSK
3. MINTEQ.ODL - overlay instructions for MINTEQLNK.CMD
4. MINTEQ.CMN - 'INCLUDE' file with common blocks and TYPE declarations
for MINTEQ routines
5. SORBS.CMN - common block for specific MINTEQ routines
6. Twenty three routines - listed in the discussion entitled DESCRIPTION
OF MEXAMS ROUTINES.
138
-------
Five data files for MINTEQ:
1. THERMO.DAT(LUN2) - default thermodynamic data
2. COMP.DAT(LUN3) - component data
3. TYPE6.DAT(LUN4) - thermodynamic data for solid phases
4. ALK.DAT(LUN5) - noncarbonate alkalinity information
5. ANALYT.DAT(LUN6) - analytical expressions of log K with temperature.
For a description of the five data files, see the previous discussion
entitled Supporting Data Files. In the POP 11/70 version files THERMO.DAT
and TYPE6.DAT must be binary with file names THERMO.BIN and TYPE6.BIN.
Copy the files to the system disk into one UIC. Then enter the
following commands.
PDS> @ MISPF4P.CMD
•
PDS> (3 MISPLNK
PDS> @ MINTEQF4P
PDS> (3 MINTEQLNK
MISP and MINTEQ.TSK are now ready to use. If the files are put on a user's
disk, then the command files will require modification to include the disk
name.
MINTEQ IMPLEMENTATION TEST CASES
This section describes the results of two example test cases run with
MINTEQ. These cases are provided to aid in testing the implementation of
MINTEQ on a new computer system.
139
-------
The first test case is a seawater test case published by Nordstrom
et al. (1979). This case is intended primarily as a comparison of the
MINTEQ modeling results to those of several other geochemical models
compared by Nordstrom et al. (1979) using the same seawater test case.
Only the thirty most important components were selected for com-
parison. Table 20 presents a comparison of the trace metal speciation
computed by MINTEQ and the results for several other geochemical models
published in Nordstrom et al. (1979).
Table 20 shows that MINTEQ results compare very closely to WATEQ2.
This is expected since the MINTEQ thermodynamic data were taken from WATEQ3
(Ball et al. 1981). The small differences between MINTEQ and WATEQ2 appear
to result from small differences in activity coefficients for the major
species (see Nordstrom et al. 1979, Table VHI). WATEQ2 uses the Davies
equation to compute many of the activity coefficients for major species,
whereas MINTEQ uses the extended Debye-Huckel with parameters taken from
Table 1 of the WATEQ3 data base (Ball et al. 1981).
A complete listing of the MINTEQ output for the seawater test case is
given in Appendix B.
The second test case is a modified form of the river water test case
given in Nordstrom et al. 1979. This test case is intended primarily as an
example of some MINTEQ features, not as a direct comparison to other
models. This test case was modified to show the following features:
« an "activity Kd",
« fixed partial pressure of C02(g),
n the input of a list of considered solids,
140
-------
TABLE 20. A COMPARISON OF SELECTED MINTEQ TRACE METAL SPECIATION
WITH THE RESULTS OF SEVERAL GEOCHEMICAL MODELS
PUBLISHED IN NORDSTROM ET AL. 1979. ALL VALUES ARE
GIVEN AS -LOG MOLALITY
Species
Ba2+
Mn2+
MnCl +
Fe(OH)§
Ni2+ 4
NiCl°
Ni C0°
Cu2+
CuCOj
Ag+
AgCl|-
Zn
/.n L u Q
Cd2+
CdCl +
CdCl^
Pb2+
PbClJ
PbCO§
EQ3
—
9.287
—
17.466
7.439
—
9.056
14.797
9.517
7.346
— —
13.746
13.591
9.602
GEOCHEM
5.93
9.33
10.26
22.94
11.28
12.41
9.23
9.74
7.91
11.21
10.01
16.79 .
12.48
8.35
7.33
11.11
9.99
9.94
11.68
11.41
16.09
SOLMNEQ WATEQF
6.857 6.821
8.478 8.654
29.376 8.880
17.897
8.071
7.664
— —
14.477
9.617
7.321
--_ ___
— —
10.442
0.372(a)
9.743
WATEQ2
6.821
8.654
8.881
17.897
8.071
7.664
8.813
9.335
7.590
10.153
9.070
14.394
9.684
7.547
7.894
11.257
9.371
9.369
11.335
11.017
9.743
MINTEQ
6.810
8.617
8.936
17.953
8.096
7.643
8.750
9.283
7.582
10,001
9,114
14.355
9.682
7.508
8.051
10.550
9.407
9.443
11.282
10.975
9.743
(a) Appears to be an error in Nordstrom et al. (1979)
141
-------
rt the process used for solid selection,
« an example of how to insert species not in the data base, and
«» computation of pE from Fe(II) and Fe(III) analysis.
The concentration of the trace constituents Zn, Cd, Pb, Cu, Ag, and Ni
were set at 100 ug/£. The solid Cerargyrite (AgCl) was found to be
supersaturated during the computation. Since Cerargyrite was included as a
considered or permissible precipitating solid, MINTEQ precipitated
Cerargyrite until the aqueous solution was in equilibrium. Seventy-one
percent of the initial silver precipitated as Cerargyrite.
The computed pE from Fe(II) and Fe(III) analysis was 1.39 or an Eh of
0.078 V. This Eh compares poorly with a value obtained by the platinum Eh
e.lectrode of 0.440 V, illustrating the discrepancies frequently found
between platinum electrode Eh values and Eh values computed from analysis of
individual elemental oxidation states.
This test case is particularly useful to users who are just beginning
to use MINTEQ. It is also useful for testing MINTEQ after its implemen-
tation on a different computer because it utilizes many of the options in
MINTEQ. The complete listing of output results is given in Appendix B. A
listing of the MINTEQ input file is given in Appendix C.
MEXAMS IMPLEMENTATION TEST CASE
The sample problem for testing the MEXAMS system simulated the effect
of loading the chemical benzo(f)quinoline into a seven compartment eutrophic
lake. Benzo(f)quinoline is in the toxic chemical- database, TOXCHEM.DAT and
the eutrophic lake is described in the canonical environment database,
CANON.ENV. For the MEXAMS test case, cadmium was modeled with the same
142
-------
Loading and eutrophic lake environment as in the original EXAMS sample prob-
lem. However, instead of using the chemical, benzo(f)quinoline, the heavy
metal option was selected from the toxic chemical database. The effect of
this option is to bypass the chemistry computations in EXAMS allowing MINTEQ
to determine the distribution of cadmium in dissolved, precipitated, or
adsorbed forms for each compartment. EXAMS is thus reduced to a model of
physical transport, i.e., advection and dispersion. Table 21 is a listing
of the EXAMS input data.
For the purposes of this example the littoral and epilimnetic com-
partments (1,3,6) were assigned a higher pH than the benthic and hypolim-
netic compartments (2,4,5,7). This provides an example of assigning
different MINTEQ eater quality data to EXAMS compartments. The concentra-
tions of major cations and anions in the MINTEQ water quality data was
assumed to be the same as averaged values for Lake Mendota, Wisconsin,
published by Hoffman and Eisenreich (1981). These values are given in
Table 22.
The initial concentration of cadmium was set at 0.02 mg/£ merely to
initialize the MINTEQ arrays. Appendix E presents an example of using MISP
to create the MINTEQ input data and an example of using MISP in the MINTEQ-
EXAMS mode for this test case. Appendix B gives a complete listing of the
MISP, EXAMS and MINTEQ output.
MEXAMS RESOURCE REQUIREMENTS
MEXAMS has been implemented on a DEC POP 11/70 using FORTRAN IV-
PLUS/IAS, VERSION 3.0. FORTRAN IV PLUS is an extended FORTRAN based on ANS
FORTRAN X3.9-1966. The following is a list of the PDP-11 FORTRAN IV
extensions of the standard which are used in MEXAMS.
143
-------
TABLE 21. SAMPLE EXAMS INPUT DATA
IM/U
I--o 3
rtVF
HtAVY METAL
0 0 n u il
till.
ElJTKOfHIC I'H
7
L
B
t
H
B
L
b
40.00
Or.SI, I- b. Y C-LUHh tl-'l PHASc. 1 b.bT UKt I i< I [ IU>l
1.500
0.2boot
5,000
4b5.o
40.00
4b.bt>
97.00
u . oooo
5. Odi)
u!231llr
C.2*40fc.
U.Y270t.
1 . 19o
90 .00
0. 5i)0'l
U.OOOO
1
1
3
1.000
il . OOOO
+ 'io 2500.
0 . buOOr
0.0000
u . OOOU
•1 . OUOL'
0 . 0 0 O c
1 11. . u
+140.?biur
+ ] b 0 . 3 o b 0 1'
+ 1b>,.41i)E+lbu
.t ltOt+150
.JObOL+lbO
.0000
. 00 00
1 .t)5o
131.0
1 .000
.2hbOL+lb
.9170L+15
. I0b0t+le
1 i 1 n
2 <* 5 7
0.5000t + n5o.2boOK»Oi>C
2.52b lu.Ou
0 . 4b7ot-o40.3S
-------
TABLE 22. CONCENTRATIONS OF MAJOR CATIONS AND ANIONS
FOR THE MEXAMS IMPLEMENTATION TEST CASE
Concentration
Constituent (mg/&)
29.04
Mg2+ 4.03
C0^~ 212.9
S0^~ 15.93
Cl~ 12.58
1. Mixe'd-mode arithmetic.
2. BYTE data type for character manipulation.
3. Direct-access unformatted input/output.
4. Comments at end of source lines.
5. OPEN and CLOSE file access control statements.
6. List-directed input/output.
7. INTEGER*4 (32 bit) data type.
8. ENTRY statement.
9. INCLUDE statement.
MINTEQ requires 64K bytes (overlaid) of memory, and 135K bytes of mass
storage for utility files. The source code consists of about 4000 card
images.
145
-------
REFERENCES
Allen, H. E., R. H. Hall and T. D. Brisbin. 1980. Metal Speciation.
Effects on Aquatic Toxicity, Environmental Sci. and Tech., Vol. 14, No. 4,
pp. 441-443.
Andrew, R. W., K. E. Biesinger and G. E. Glass. 1977. Effects of Inorganic
. Complexing on the Toxicity of Copper to Daphnia Magna. Water Research,
Vol. 11, pp. 309-15.
Ball, J. W., E. A. Jenne and D. K. Nordstrom. 1979. "WATEQ2: A
Computerized Chemical Model for Trace and Major Element Speciation and
Mineral Equilibria of Natural Waters." In Chemical Modeling in Aqueous
Systems, ed. E. A. Jenne, pp. 815-835. Amer. Chem. Soc. Symp. Series 93.
Ball, J. W., E. A. Jenne and M. W. Cantrell. 1981. WATEQ3: A Geochemical
Model with Uranium Added. U.S. Geol. Survey, Open File Report 81-1183.
Chakoumakos, C., R. C. Russo and R. V. Thurston. 1979. Toxicity of Copper
to Cutthroat Trout (Salmo Clarki) Under Different Conditions of
Alkalinity, pH and Hardness, Environmental Sci. and Tech., Vol. 13, No. 2,
pp. 213-219.
146
-------
Chapman, B. M. 1982. Numerical Simulation of the Transport and Speciation
of Nonconservative Chemical Reactants in Rivers, Water Resources Research,
Vol. 18, No. 1, pp. 155-167.
Chapman, B. M., R. 0. James, R. F. Jung and H. G. Washington. 1982.
Modeling the Transport of Reaching Chemical Contaminants in Natural
Streams, Aust. J. Mar. Freshw. Res., Vol. 33, pp. 617-628.
Dana, E. S., and W. E. Ford. 1957. A Textbook of Mineralogy. John Wiley
and Sons, Inc., New York, New York.
Felmy, A. R., D. C. Girvin and E. A. Jenne. 1983. MINTEQ - A Computer
Program for Calculating Aqueous Geochemical Equilibria. Final Project
Report EPA contract 68-03-3089.
Hoffmann, M. R., and S. J. Eisenreich. 1981. "Development of a Computer-
Generated Equilibrium Model for the Variation of Iron and Manganese in the
Hypolimnion of Lake Mendota." Environmental Sci. and Tech., Vol. 15,
No. 3, pp. 339-344.
Jenne, E. A., J. W. Ball, J. M. Burchard, D. V. Vivit and J. H. Barks.
1980. "Geochemical Modeling: Apparent Solubility Controls on Ba, Zn, Cd,
Pb and F in Waters of the Missouri Tri-State Mining Area." In. Trace
Substances in Environmental Health-XIV, ed. D. D. Hemphill, pp. 353-361.
University of Missouri, Columbia, Missouri.
147
-------
Lindsay, W. L. 1979. Chemical Equilibria in Soils. John Wiley and Sons,
New York, New York.
McDuff, R. E., and F. M. Morel. 1973. Description and Use of the Chemical
Equilibrium Program REDEQL2. Tech. Report EQ-73-02. Keck Lab., Environ.
Eng. Sci., Cal. Tech., Pasadena, California.
Morel, F., and J. J. Morgan. 1972. "A Numerical Method for Computing
Equilibria in Aqueous Chemical Systems." Environ. Sci. and Tech., Vol. 6,
pp. 58-67.
Morel, F. M. M., J. C. Westall, C. R. O'Melia and J. J. Morgan. 1975. Fate
of Trace Metals in Los Angeles County Wastewater Discharge, Environmental
Sci. and Tech., Vol. 9, No. 8, pp. 756-761.
Munro, J. K. Jr., R. J. Luxmore, C. L. Begovich, K. R. Dixon, A. P. Watson,
M. R. Patterson and D. R. Jackson. 1976. Application of the Unified
Transport Model to the Movement of Pbs Cd, Zn, Cu and S through the
Crooked Creek Watershed, ORNL/NSF/EATC-28, Oak Ridge National Laboratory,
Oak Ridge, Tennessee.
Nordstrom, D. K., L. N. Plummer, T. M. L. Wigley, T. J. Wolery, J. W. Ball,
E. A. Jenne, et al. 1979. "A Comparison of Computerized Chemical Models
for Equilibrium Calculations in Aqueous Systems." In Chemical Modeling in
Aqueous Systems, ed. E. A. Jenne, pp. 857_892. Amer. Chem. Soc. Symp.
Series 93.
140
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Orolb, G. T., D. Hrovat and F. Harrison. 1980. "Mathematical Model for
Simulation of the Fate of Copper in a Marine Environment," in Particulates
in Hater. M. C. Kavanaugh and J. 0. Leckie, eds., Advances in Chemistry
Series 189, Americal Chemical Society, Washington, D.C.
Raridon, R. J., D. E. Fields and G. S. Henderson. 1976. Hydrologic and
Chemical Budgets on Walker Branch Watershed - Observations and Modeling
Approaches, ORNL/NSF/EATC-24, Oak Ridge National Laboratory, Oak Ridge,
Tennessee.
Robie, R. A., B. S. Hemingway, C. M. Schafer-and J. L. Haas, Jr. 1978.
"Heat Capacity Equations for Minerals at High Temperatures." U.S.G.S.
Open-File Report.
Truesdell, A. H., and B. F. Jones. 1974. "WATEQ, A Computer Program for
Calculating Chemical Equilibria of Natural Waters." U.S. Geol. Survey J.
Res. 2:233-248.
Westall, J. C., J. L. Zachary and F. M. M. Morel. 1976. MINEQL, A Computer
Program for the Calculation of Chemical Equilibrium Composition of Aqueous
Systems. Tech. Note 18, Dept. Civil Eng., Massachusetts Institute of
Technology, Cambridge. Massachusetts.
149
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APPENDIX A
MINTEQ PROGRAM LISTING
This appendix contains a complete listing of the POP 11/70 version of
MINTEQ..
Appendix A can be obtained by writing to the following address:
Environmental Protection Agency
Environmental Research Laboratory
College Station Road
Athens, Georgia 30613
150
-------
APPENDIX B
TEST CASE RESULTS
This appendix contains complete listings of the MINTEQ output for the
sea water and river water test cases as well as MISP, EXAMS and MINTEQ
outputs for the MEXAMS implementation test case.
Appendix B can be obtained by writing to the following address:
Environmental Protection Agency
Environmental Research Laboratory
College Station Road
Athens, Georgia 30613
151
-------
APPENDIX C
DESCRIPTION OF THE MINTEQ INPUT FILE
This appendix describes how to setup the sample description file for
running the VAX and POP 11/70 versions of MINTEQ. A detailed description of
the options available to the user accompanies the file descriptions.
Examples of MINTEQ input files are included.
The sample description file is broken.into three sections. Each sec-
tion is separated by a blank line. There should be three and only three
blank lines in the sample file. The three sections will be called Basic
Input Data, Type Modifications and insertion of Species. The format field
designations for each line are given in parentheses following the line
designation.
Section 1 - Basic Input .Data
Line 1 (A80). Alphanumeric description of the sample.
Line 2 (ABO). Alphanumeric description of the sample.
Line 3^a'. Water temperature, analytical units and fixed ionic
strength designation
(a) This line is free formatted on the VAX version.
152
-------
The water temperature in degrees Celcius is entered followed by the
analytical units. In the VAX version, the temperature and units must be
separated by a space and the units enclosed in quote marks. The POP 11/70
version follows the designated format fields. The analytical unit designa-
tions can be either 'PPM1, 'MG/11, 'MOL', or 'MEQ/L'. These designations
stand for parts per million, milligrams per liter, molality and mi 11i -
equivalents per liter, respectively. The fixed ionic strength is entered
following the analytical units. In the VAX version there must be a space
between the analytical units and the ionic strength. The POP 11/70 version
follows the format fields. If the ionic strength is not fixed, enter 0.0
following the analytical units.
Line 4[8(I1,IX)]. This line contains the run specific user options.
Option 1. The inorganic carbon input option.
(0) = Total inorganic carbon
(1) = Total alkalinity
Option 2. The Debug print option. This is generally used only when
modifications have been made to the code and the values of certain
arrays must be checked.
(0) = No Debug printout.
(1) = Prints the values of the IDX, C, IDY, GAMMA, C and Y arrays
153
-------
(3) = Prints the NNN, NN(1), NN(2) and the IDY, GK, GK1 arrays in
subroutine KCORR.
(4) = Prints the IDX, X, IDY, L and GK arrays every iteration in
subroutine SOLID and the saturation index for the solid
added to the phase assemblage in subroutine SOLIDX.
Option 3. The charge balance option.
(0) - Terminates execution of the program if the initial charge in
balance is greater than 30 percent.
(1) - Does not terminate execution regardless of the initial
computed charge imbalance.
Option 4. Considered solids and. print option.
(0) - Do not allow all of the solids in the data base to
precipitate or dissolve. The only solids considered will be
those entered in the next input section under type
changes. Print the problem results after the initial
aqueous speciation plus solids problem is solved and after
all type V solids are either in equilibrium or
undersaturated.
(1) - Allow all solids in the data base to precipitate if they
become oversaturated. That is, designate all solids in the
data base as Type V. Print the problem results only after
the entire problem has been solved.
(2) - Consider all solids in the data base. Print the problem
results after the initial user specified problem has been
154
-------
solved and again after all Type V solids are undersaturated
or in equilibrium.
(3) - Consider all solids in the data base. Print the problem
results following the selection of every solid and after all
of the solids are in equilibrium or undersaturated.
Option 5. The total number of iterations option.
(0) - Allow 40 iterations.
(1) - Allow 10 iterations.
(2) - Allow 100 iterations.
(3) - Allow 200 iterations.
The 100 or 200 iteration options should be, selected if a large number
of solids have been designated as considered solids. The ten iteration
option is only useful when debugging the program.
Option 6. The pH variation option.
(0) - Do not allow the pH to automatically vary during precipi-
tation/dissolution of solid phases.
(1) - Allow the pH to vary during precipitation/dissolution of
solid phases. Not for this option to work all solid phases
must be declared Type V in the initial input.
Option 7. The fixed ionic strength option.
(0) - Allow MINTEQ to compute the ionic strength.
(1) - Fix the ionic strength at the value designated on line 3.
155
-------
Option 8. The numerical method option.
(0) - Use only Newton-Raphson iteration.
(1) - Use a combination of Newton-Raphson and a modified line
search. This option should only be used after consulting
the technical manual.
Option 9.(a) Output Option
(0) - Do not print on initial listing of the thermodynamic data.
X
(1) - Print a listing of the thermodynamic data.
Line 5 [I1.1X,4(F6.2,1X)]. This line is for input of adsorption
parameters other than the mass total and activity guesses. The first
parameter on this line is the adsorption model being used (II field). The
options are:
0 - No Adsorption,
1 - Activity Kd, Langmuir isotherm, Freundlich isotherm,(a)
2 - Constant Capacitance Double Layer Model,
3 - Triple Layer Site Binding Model.
The next four inputs on this line are:
- Solid Concentration (g/1),
- Specific Surface Area (m2/g),
- Inner Layer Capacitance (F/m2),
- Outer Layer Capacitance (F/m ),
(a) Available only on the VAX version.
156
-------
input in this order. None of the last four inputs are required for the
activity Kd. The constant capacitance model does not require an outer layer
capacitance. The triple layer model requires all four data inputs.
Line 6+ (I7.IX,E9.3.IX,F6.2). Component input lines. There are as
many of these lines are there are components. A blank line must follow the
last component.
The first specification (17) is the component ID number. Component ID
numbers are given in Table 3. The second specification (E9.3 field) is the
total analytical mass in the units designated on line 3. The only exception
occurs when the constant capacitance or triple layer models are used. In
such cases the analytical mass for the surface sites (SOH1 or SOH2 compo-
nents) must be specified in sites per gram. The third specification on this
line is a guess at the log of the component activity. If you leave this
field blank the initial estimate of the activity will be the analytical
molality divided by 100. Remember you need one line for every component and
a blank line after the last component.
Section 2 - Type Modifications
This section is for changing the default species designations. The
default type specifications have been described in Section 5.
The first line of this section contains the first species type desig-
nation and the number of species of this type Format (13, IX, 13). The type
designations can range from two to six. Then for each species of the
entered type a line is included (17, IX, E9.3, IX, F6.2) designating infor-
mation for that species. The first field specification is for the species
I.D. number. Species I.D. numbers for components (Type I) are given in
157
-------
Table 3. All other species I.D. numbers can be found in the listing of
Thermodynamic Data given in the MINTEQ Technical Report. The next two
specifications are for the new log K and enthalpy of reaction. These are
both optional and if not included the default values in the thermodynamic
data base are used. A blank line also ends this section. In the case of
Type IV species with an initial mass total (in moles/£) there is an addi-
tional input field for the initial mass. This input field follows the input
of the enthalpy of reaction resulting in four inputs on one line. The input
format for Type IV species is (17, IX, E9.3, IX, F6.2, IX, E10.3). For
examples of necessary species modifications to solve specific problems see
Section 5.
Section 3 - Insertion of Species Not in the Data Base
The first line is for designating the species type and the number of
new species of this type (Format 13, IX, 13). The species type can only
range from two to six. The next lines contain the data for the new species
of the specified type. There are three lines for each species. The first
line of species data is in Format (17, IX, A12, 2F10.4, 2F8.3, 3F5.2,
F9.4). The format fields correspond to the following data: I.D. number,
name, enthalpy of reaction, log K, minimum log K, maximum log K, charge,
Debye-Huckel A parameter, Debye-Huckel B parameter and molecular weight
respectively. Only the ID number and log K are absolutely essential. For a
description of the Debye-Huckel parameters see the MINTEQ Technical Report.
The second line of data is in Format [F5.2, IX, II, IX, 6(F7.3, IX, 13,
IX)]. The format fields correspond to: carbonate alkalinity factor, number
of components in the reaction and the stoichiometry and ID number for up to
158
-------
six components. The carbonate alkalinity factor is only useful if the input
inorganic carbon is an alkalinity value. A description of the carbonate
alkalinity factor is given in the MINTEQ Technical Report. The third line
is in Format [3(F7.3, IX, 13, IX)] and is merely a continuation of the
component entries for the inserted species. In the VAX version, the third
line is in format [3(F7.3, IX, 13, IX), II, 3 (F7.3, IX, 13, IX)]. The
format field beginning with II is for inserting species informaton into the
"B" matrix. Such information is only useful when the component stoichio-
metries in the mass action expressions are different from the stoichio-
metries in the mass balance equation. The latter format fields correspond
to the number of components in the "B" matrix, stoichiometry of the compo-
nent and component I.D. number. This section is also terminated with a
blank line.
There occasionally can be a problem with determining species ID numbers
for inserted species. The problem is that an ID number may be selected that
matches an ID number already in the data base. The problem is usually in
determining the last digit for aqueous species and the last two digits for
minerals and solids since these are arbitrary designations. Table C-l gives
the highest ID numbers for aqueous species and Table C-2 gives the highest
ID numbers for minerals and solids. To obtain the correct ID number first
determine the first six digits for aqueous species and the first five digits
for solids (see Section 5). The last digits can then be any values higher
than those in Tables C-l or C-2. Tables C-3 and C-4 give examples of the
input data file.
159
-------
TABLE C-1. HIGHEST I.P. NUMBERS OF AQUEOUS COMPLEXES
First
Six
Digits
020130
020141
020142
020180
020270
020330
020380
020491
020492
020730
020732
030270
030330
030732
090270
100330
150140
150270
150330
150580
150732
Last
Digit
2
0
0
3
0
1
3
0
0
4
0
3
3
1
3
0
1
0
0
2
0
First
Six
Digits
160130
160140
160141
160142
160180
160270
160330
160380
160492
160730
160732
230180
230730
231140
231141
231142
231180
231270
231330
231730
231732
280330
280580
280730
280732
Last
Digit
1
1
0
0
3
1
4
1
0
3
1
1
1
2
0
0
3
0
4
0
0
1
1
1
0
First
Six Last
Digits Digit
281141
281142
281180
281270
281330
281580
281732
330060
330061
330090
330140
330141
330142
330270
330490
330580
330730
330732
330770
410580
410732
440732
0
0
2
2
5
1
1
2
3
0
1
0
0
2
0
1
1
0
1
0
0
0
First
Six Last
Digits Digit
460140
460270
460330
460580
460732
470002
470140
470180
470270
470330
470492
470732
490732
500140
500270
500580
500732
540130
540140
540180
540270
540330
540732
1
0
0
2
0
1
0
2
0
1
0
0
0
1
0
0
0
0
2
1
0
2
1
First
Six Last
Digits Digit
600130
600140
600180
600270
600330
600380
600492
600730
600732
731730
770270
800330
891180
891270
891330
891580
891732
893140
893180
893270
893330
893580
893732
893770
1
2
3
3
5
1
0
1
1
4
0
0
0
5
5
3
1
2
0
3
2
4
1
0
First
Six Last
Digits Digit
900330
901330
901732
902180
902270
902330
902732
903002
903270
903330
903492
903732
950130
950140
950180
950270
950330
950380
950730
950732
0
4
0
0
3
1
0
7
3
3
0
1
1
2
4
0
3
1
1
1
-------
TABLE C-2. HIGHEST I.D. NUMBERS OF MINERALS AND SOLIDS
First
Five
Digits
Last
Two
Digits
First
Five
Digits
Last
Two
Digits
First
Five
Digits
Last
Two
Digits
First
Five
Digits
Last
Two
Digits
First
Five
Digits
Last
Two
Digits
First
Five
Digits
Last
Two
Digits
00020
00060
10020
10160
10230
10231
10280
10470
10540
10600
10731
10900
10950
20020
20030
20160
20230
20231
20281
20460
20470
20471
20540
20600
20770
20891
20893
00
00
00
01
03
02
03
00
00
01
00
00
02
00
03
02
00
02
02
00
03
00
01
05
04
01
03
20900
20901
20902
20950
30060
30061
30100
30150
30230
30231
30280
30281
30410
30440
30470
30471
30600
30891
30901
30902
30903
40020
40160
40230
40600
40950
41020
41160
41230
41231
41281
00
00
00
06
01
00
00
01
00
00
00
01
00
00
00
00
01
01
01
02
00
00
00
00
01
00
00
03
00
01
00
41470
41500
41600
41900
41901
41902
41903
41950
42020
42100
42150
42160
42230
42231
42600
42800
42902
42950
43020
43060
43160
43230
43600
43950
50020
50100
50150
50160
50231
00
00
04
00
01
00
00
02
00
00
00
00
00
01
00
00
00
00
00
00
00
00
00
00
00
00
03
00
02
50280
50460
50470
50500
50540
50600
50800
50893
50950
51231
51893
51950
'52160
52600
52950
60020
60030
60100
60150
60160
60230
60231
60280
60281
60410
60460
60470
60471
60500
60540
60600
00
03
00
01
00
03
00
00
01
00
03
00
00
00
00
00
01
00
01
05
00
05
00
01
02
00
00
00
02
02
04
60800
60902
60950
70020
70100
70150
70160
70231
70231
70280
70281
70410
70460
70470
70490
70500
70540
70600
70800
70891
70893
70902
70950
72030
72100
72150
72231
72281
72470
72540
72600
72950
00
00
06
00
00
02
00
00
01
01
00
00
00
01
00
00
00
07
00
00
01
00
00
00
00
00
00
00
00
00
00
00
73020
73150
73280
73460
73470
73490
73500
73600
80150
80460
80540
80600
80950
82150
82160
82460
82600
82950
84150
84500
86030
86280
86410
86460
02
03
00
02
00
00
02
01
00
00
00
00
00
01
00
00
00
00
03
03
02
00
01
04
-------
TABLE C-3. MINTEQ INPUT DATA FOR THE SEAUATER TEST CASE _
THIS IS THE SLAwATtk TtST CASE PUBLISHED IN NURDSTKUM tT AL.U979)
ONLY THK THIRTY MOST IMPORTANT COMPONENTS WERE MODELED.
25.0 «G/b O.Ou
10000000
0 0.00 0.00 0.00 u.OO
C^- 150 4.219t+02 -2.00
, ,,, 460 1.321E+03 -1.00
jL 500 1.102t + 04 -1.00
K 410 4.0b4fc>02 -3.00
( 1^0 1.980bE+4 -1.00
732 2.775JL + 03.-2.00 i '" °' ''
800 H.330E+00 -5.00
090 2.598E+U1 -b.OO
7/0 7.004K-MJO -5.00
270 1.423E+00 -0,00
100 2.0bOE-02 -6,00
530 fe.140t.-02 -7,00
492 2.968E-01 -5,00
490 3.070E-02 -5.00
281 2.U50E-03 -b.OU
280 O.OOOE-00 -10.0
470 2.0bOK-04 -9.00
030 2.050L-03 -9.0U
950 5.014L-03 -9.00
160 I»u20t-0>0
2302310
162
-------
TABLE C-4. MINTEQ INPUT DATA FOR THE RIVER UATER TEST CASE
R
IVKH ft A
AT -3.5
9
'I
1
TK..
AT
,bO MG/L
000
0.00
boo
100
410
1SU
460
770
140
190
732
090
270
580
492
490
2dO
2*31
030
950
160
600
231
540
020
330
001
990
3 4
330
990
2812800
3301403
5 45
5023100
4223100
4223101
2023100
4123101
5123100
2023101
7023101
4195000
5095000
5095001
4295000
2095000
2095001
2
1.
I.
I.
I.
7.
1,
3.
9.
7.
'2.
1.
2.
H.
1.
1,
7.
5.
1.
1.
1.
I.
1.
1.
0.
0.
K Tt.S'l CA6t.
M, ACT! VI
0 . 0 o
oou
0 . 0 0
200e>01
OUUt-Ol
4 U 0 t + 0 0
22'jh + ul
5uOe>00
3b2btul
ft^dt-t-Ol
9uOt>uO
700E.toO
H&Ot-i; 1
OUOK-Ul
100t'-01
9eut-oi
440t-01
500b-02
OOOt-04
OOOt-03
000fc.-0l
OoOE-01
OOOt-01
000h'-0l
OOOt-01
OUOt-01
ouot-oo
ooot-oo
O.OOOb-00
8,01
21 ,6fc
TY
. t't Ciif-PUlbi) FkOi th-t-2 Af«u ffc. + 3,Ll!^ PCCI2 St.!
Ku KLIH CU,AulJ wtTAL. CUNCb.m'l HnTUNS = 0.1 Wb/L
0 . 0 (j (j . (j v
-4.
-5.
-6.
-4.
-b.
-b.
-b.
-b.
-5.
-b.
-5.
-9.
-4.
-5.
-b.
00
00
01)
00
00
00
00
00
<<0
00
00
00
00
00
uO
-14.0
-10
-6.
-6.
-6.
-7.
•f t
-7.
-w.
2.
.0
00
00
00
00
00
00
01
00
0.00
163
-------
MINTEQ TABLE C-4. (contd)
2095002
2095003
2095004
5195000
6095000
5016000
4116000
4116001
4116002
4216000
2016000
2016001
7016000
6016004
5060000
4260000
6060003
2060004
5060003
7060006
5054000
2054000
7054000
6054001
4102000
5002000
4202000
7002000
6010000
4210000
5010000
6 1
1
2 1
9901600
2
6 1
1007321
2
SUH-CU
1.00
IbO
BASU4CA)
1.00 100
1,00 990
1.00 732
10.00
9.04
164
-------
APPENDIX D
MISP PROGRAM LISTING
This appendix contains a complete listing of MISP-
Appendix D can be obtained by writing to the following address:
Environmental Protection Agency
Environmental Research Laboratory
College Station Road
Athens, Georgia 30613
165
-------
APPENDIX E
EXAMPLE MISP RUNS
This appendix contains two example MISP runs. Both runs are for the
MEXAMS implementation test case described in the Programmers Supplement.
The first run prepares a MINTEQ input file. The water quality data for
this run are given in Table 22. Cadmium was given an arbitrary "activity"
Kd and the pH was fixed at 9.
The second example is a MISP run in the MINTEQ-EXAMS mode. The EXAMS
environment is a seven compartment eutrophic lake with different water
quality conditions in the epilimnetic/1ittoral compartments than in the
hypolimnetic/benthic compartments. File MENDOTA2.DAT was created by copying
file MENDOTA.DAT created in the first example and changing the pH. Appen-
dix C should be consulted for a description of how to prepare a MINTEQ input
file without using MISP.
166
-------
sci:.-. RUN MISP
?2t28:05
WELCOME ro MEXAMS
METALS EXPOSURE ANALYSIS MODELING SYSTEM
BA TTELLE -NORTHWEST LABORATORIES
YOU HAVE A CHOICE OF THE FOLLOWING MODELS.
1) EXAMS-ONLY MODEL UITHOUT MINTEQ
2) MINTEQ-ONLY MODEL UITHOUT EXAMS
3) MINTEQ-EXAMS MOHEL
ENTER MODEL NUMBER. (ID '2
DO YOU HAVE A MINTEQ FILE REABY ? ,< N
QUESTION *1I ENTER TITLE OF SIMULATION. '
THIS FILE CONTAINS SOME REPRESENTATIVE WATER QUALITY DATA FOR A EUTROPHIC
QUESTION *2: ENTER DESCRIPTION OF UATER BODY. >
LAKE. THE PH WAS ARBITRARILY SET TO 9.0 WITH AN ACTIVITY KD OF 1.0
QUESTION *3: SELECT DATA UNITSI-
MG/L
PPM
MOL
MEQ/L
MG/L
QUESTION *•»: ENTER TEMPERATURE Y
ENTER SELECTION NUMBER.
1) PH '
2) TOTAL H '
ENTER PH. 9.0
QUESTION *7: IF SOLIDS ARE SELECTED TO DISSOLVE OR PRECIPITATE
DO YOU WANT TO ALLOW THE PH TO VARY' ::N
QUESTION »8t DO YOU HAVE AN EH VALUE OR PO
YOU UANT TO ENTER THE ELECTRON AS A COMPONENT' '-N
QUESTION *10: DO YOU HAVE A MEASUREMENT OF TOTAL INORGANIC CARBON' (Y/N)
ENTER TOTAL INORGANIC CARPON IN UNITS OF MG/L 212.7
167
-------
DO YOU WANT 10 GUESS THE LOG OF THE C03 ACTIVITY? (Y/N) ,-Y
ENTER THE LOG OF THE C03 ACTIVITY. —6.00
QUESTION 1111 IF A LARGE NUMBER OF MINERALS UIILL PRECIPITATE OR DISSOLVE,
OPTION 3 SHOULD BE USED IN THE FOLLOWING QUERY.
HOI4 MANY ITERATIONS WILL YOU ALLOW?
0) 40
1) 10
I!) 100
3) 200
ENTER OPTION NUMBER. :-0
QUESTION *12! DO YOU WANT TO OVERRIPE THE CHARGE BALANCE CRITERIA' Y
IF THE ANSWER TO THE FOLLOWING QUESTION IF 'NO', THEN ONLY
SOLIDS IN SAMPLE DESCRIPTION WILL BE CONSIDERED.
QUESTION *13! DO YOU WANT TO ALLOW ALL SOLIDS IN THE DATA BASE TO
PRECIPITATE IF THEY BECOME OVERSATURATED? (Y/N) >N
QUESTION *14! ENTER DEBUG OUTPUT OPTION NUMBER
**CAUTION DEBUG OUTPUT WILL ONLY BE USEFUL IF YOU
ARE THOROUGHLY FAMILIAR WITH MINTED.
0) NO DEBUG
1) ALL ARRAYS EACH ITERATION
2) ALL ARRAYS IN ALKOR
3) LOOK ARRAYS IN KCDRR
4) ALL ARRAYS IN SOLID AND SOLIDX
0
IN ANSWERING THE NEXT QUESTION REMEMBER YOU SHOULD
ONLY USE THE MODIFIED LINE SEARCH IF A PREVIOUS
RUN HAS FAILED TO CONVERGE!
QUESTION *15! fin YOU WANT TO USE THE MODIFIED LINE SEARCH AND
NEWTON-RAFHSON ITERATION7 > (Y/N) >N
QUESTION t 161 DOES YOUR SAMPLE CONTAIN AG f (Y/N) >N
QUESTION t 171 DUES YOUR SAMPLE CONTAIN AL ? (Y/N> ,;N
QUESTION * ISA DOES YOUR SAMPLE CONTAIN H3AS04 ? (Y/N) >M
QUESTION * 1GB DOES YOUR SAMPLE CONTAIN H3AS03 » (Y/N) . N
QUESTION t 191 DOES- YOUR SAMPLE CONTAIN H3B03 •> (Y/N) >N
QUESTION * 201 DOES YOUR SAMPLE CONTAIN BA 7 (Y/N) >M
QUESTION t 21! DOES YOUR SAMPLE CONTAIN BR ^ (Y/N) N
QUESTION * :_'::: DOER YOUR SAMPLE CONTAIN FULVATE ? (Y/N> N
QUESTION t 231 DOES YOUR SAMPLE CONTAIN HUMATE ~> (Y/N) N
QUESTION t 241 DOES YOUR SAMPLE CONTAIN CA ^ (Y/N) .Y
ENTER THE TOTAL CA 29.04
DO YOU WANT TO GUESS THU ACTIVITY OF CA 1 (Y/N) N
I Reproduced from
_°est available co
copy.
168
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QUESTION If 25! HULS fUUK SAMPLE CUNIA1N LLl , '. i / N > r
ENTER THE TOTAL CH ',0.02
DO YOU UANT TO GUESS THE ACTIVITY OF CD f (Y/N) !: N
QUESTION t 26! DOES YOUR SAMPLE CONTAIN CL ? N
QUESTION t 27:'DOES YOUR SAMPLE CONTAIN CS ' (Y/N) >N
QUESTION V 28A DOES YOUR SAMPLE CONTAIN CU+2 ? (Y/N) ,N
QUESTION * 28B DOES YOUR SAMPLE CONTAIN CU+1 f (Y/N) ^N
QUESTION * 2V. LlOES YOUR SAMPLE CONTAIN F ' (Y/N) ", N
QUESTION t 30A DOES YOUR SAMPLE CONTAIN FE + 2 ~> (Y/N) ^N
QUESTION * 30B DOES YOUR SAMPLE CONTAIN FE+3 f (Y/N) >N
QUESTION * 31: DOES YOUR SAMPLE CONTAIN I ? (Y/N) >N
QUESTION t 32! DOES YOUR SAMPLE CONTAIN K 7 (Y/N) >N
QUESTION * 33! DOES YOUR SAMPLE CONTAIN LI ? (Y/N) >N
QUESTION * 34: DOES YOUR SAMPLE' CONTAIN MG * (Y/N) >Y
ENTER THE TOTAL MG :4.03
DO YOU UAN. TO GUESS THE ACTIVITY OF MG 7 (Y/N) >N
QUESTION t 35A DOES YOUR SAMPLE CONTAIN MN+2 * (Y/N) >N
QUESTION t 35B DOES YOUR SAMPLE CONTAIN MN+3 ? (Y/N) >N
QUESTION t 3«A DOES YOUR SAMPLE CONTAIN NH4-f "> (Y/N) ,N
QUESTION t 3AB DOES YOUR SAMPLE CONTAIN N02- ? (Y/N) ^N
QUESTION t 3AC DOES YOUR SAMPLE CONTAIN N03- ? (Y/N) ;N
QUESTION * 37! DOES YOUR SAMPLE CONTAIN Nft ? (Y/N) ~:U
QUESTION * 381 DOES YOUR SAMPLE CONTAIN NI ? (Y/N) >N
QUESTION t 39: DOES YOUR SAMPLE CONTAIN P04 7 (Y/N) >N
QUESTION t 40! DOES YOUR SAMPLE CONTAIN PB * (Y/N) N
QUESTION t 41B DOES YOUR SAMPLE CONTAIN G ' (Y/N) -N
QUESTION * 41C DOES YOUR SAMPLE CONTAIN TTL SULFIDE ' .• N
QUESTION t 42: riHF.S milR SAMPLE CONIATN H4BID4 T (Y/N) N
169
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uuEsnoH * "-'•: putb ruuN SAMPLE LUNIAIN 'JR ' N
QUESTION * -14A HOES YOUR SAMPLE CONTAIN 1102 + 2 •> (Y/N) JN
QUESTION * 44B HOES YOUR SAMPLE CONTAIN U02 + ' N
QUESTION * 45: DOES YOUR 'SAMPLE CONTAIN ZN ? (Y/N> >N
QUESTION »46: DO YOU WANT TO CONSIDER ADSORPTION? Y
UHICH ADSORPTION ALGORITHM?
1) ACTIVITY KDrACTIVITY LANGMUIR OR ION EXCHANGE
2) CONSTANT CAPACITANCE MODEL
3) TRIPLE LAYER SITE BINDING MODEL
-•1
WILL YOU BE CONSIDERING TUO DIFFERENT SURFACE SITES? N
WILL YOU BE USING AN ACTIVITY KD? (Y/N)Y
HOU MANY ADSORPTION REACTIONS WILL YOU CONSIDER?'1
ENTER REACTION ID NUME'ER. >9901600
ENTER REACTION NAME. -'SO-CD+2
ENTER ACTIVITY KD (CANNOT BE ZERO OR NEGATIVE). ,;1.00
CHECK MEXAMS USERS GUIDE FOR COMPONENT ID.
ENTER ID NUMBER FOR ADSORBING COMPONENT. .160
ENTER ID NUMBER FOR SURFACE (IE 990 OR 991)>990
WILL YOU BE USING AN ACTIVITY
LANGMUIR ISOTHERM? (Y/N) N
UILL YOU BE CONSIDERING ION EXCHANGE REACTIONS7(Y/N)N
DUESTION *47: DO YOU WANT TO ENTER />|NY REDOX REACTIONS' (Y/N) :• N
QUESTION *48! DO YOU WANT TO INCLUDE GASES AT A
FIXED PARTIAL PRESSURE? (Y/N) 'N
QUESTION t47: DO YOU WANT ANY SOLIDS TO PE PRESENT REGARDLESS OF
HOU MUCH HAY DISSOLVE? (Y/N) ,-N
*** TYPE 4 ENTRIES ***
QUESTION *50! DO YOU UANT TO INCLUDE SOLIDS WHICH
ARE ONLY ALLOWED TO DISSOLVE A SPECIFIED AMOUNT? (Y/N) N
*** TYPE S ENTRIES ***
QUESTION *5K ARF THERE ANY SOLIDS THAT YOU WILl^
ALLOW TO PRECIPITATE IF THEY BF.COME OVERSATURATED ">
Y/N) Y
170
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_,,iun NUMKER OF SOLIDS, 6
ENIER SOLI!/ I.D. NUMLlER. -5016000
ENTER SOLID I.D. NUMBER. •'1116000
ENTER SOLID I.D. NUMBER. ':<4116001
ENTER SOLID I.D. NUMBER. .2016001
ENTER SOLID I.D. NUMBER. 12016000
ENTER SOLID I.D. NUMBER. .'6016003
DO YOU UIANT TO CHANGE THE EQUILIBRIUM CONSTANT FOR
ANY SOLIDS YOU JUST E.NTERED? :-N
DO YOU UANT TO CHANGE THE ENTHALPY OF FRACTION FOR
ANY SOLIDS YOU JUST ENTERED' (Y/N) -N
*** TYPE 6 ENTRIES ***
QUESTION *52: ARE THERE ANY SPECIES YOU DO NOT
UANT TO CONSIOER DURING THE EQUILIBRIUM COMPUTATIONS? (Y/N) :N
QUESTION *53: DO YOU UftNT TO CHANGE THE EQUILIBRIUM CONSTANT OR
HEAT OF REACTION FOR ANY SPECIES IN THE DATA BASE
UHICH THIS PROGRAM HAS NOT ALREADY CHANGED? (Y/N) >N
QUESTION *5-»: DO YOU WANT TO ADD SPECIES TO THE
DATA BASE FOR THIS RUN ONLY' Y
*** COMPONENT ENTRIES ***
I.P. COMPONENT
ISO CA
160 CD
180 CL
460 MG
732 TTL SULFATE
990 SOH1
TOTAL
0.29040E+02
0.20000E-01
0.12580E+02
0.40300E+01
0.15930E+02
O.OOOOOE+00
N
ACT. GUESS
O.OOOOOE+00
O.OOOOOE+00
O.OOOOOE+00 '
O.OOOOOE+00
O.OOOOOEJ-00
O.OOOOOE+00
ARE THERE ANY CHANGES? (Y/N)
SELECT RUN OPTION!
1) STORE DATA IN A FILE.
2) MODEL DATA.
ENTER OPTION NUMElER > 1
ENTER FILE NAME. MENDOTA.PAT
TIME 501.1854
TTOOB — STOP
171
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SCI- - RUN MI iiF
l^: 39:t?
ULLCOME 10 Mt'XAMP
hETAI b EXPOSURE ANALYSIS MOUELINR SYSTEM
BATTELLE -NORTHWEST LABORATORIES
YOU HAVE ,1 CHOICE OF THE FOLLOWING MODELS.
1) EXAMS-ONLY MODEL WITHOUT MINTEQ
2) MINIER-ONLY MODEL WITHOUT EXAMS
3) MINTEfl-EXAMS MODEL
FNTER MODEL NUMBER. (ID >3
SELECT THE METAL ID FROM THE FOLLOWING TABLE.
(U
20 AG
61 H3AS04
1AO CH
231 CUt-2
•i40 NI
600 P8
950 ZN
160
HOW MANY MINTEQ INPUT FILES WILL BE NEEDED? v
ENTER NUMBER OF COMPARTMENTS FOR FILE 1 3
ENTER COMPARTMENT NUMBERS FOR FILE 1
SEPARATE THE NUMBERS WITH A SPACE OR COMMA.
ENTER NUMBER OF COMPARTMENTS FOR FILE 2 't
ENTER COMPARTMENT NUMBERS FOR FILE 2
SEPARATE THE NUMBERS WITH A SPACE OR COMMA. ':-2,4,5.7
HOW MANY TIMES DO YOU WANT TO USE MINTEQ TO
UPDATE THE STEADY STATE CONCENTRATION » -2
HOW OFTEN DO YOU WANT TO USE MINTEQ FOR
PERSISTENCE COMPUTATIONS f
SELECT OPTION NUHIJ(-R FROM THE FOLLOWING LIST.
1) EVERY TIME
?! EVERY OTHER TIMt
3) EVERY THIKD I IMF
-t) ItUCRY FOURTH TIME
5) I;VFH/ i trw TIME
A) NCI PERSISTENCE UPDATE
SH.tHl MINTEtl OUTPUT OPTION!
J ) FULL M1NTEO PRINTOUT.
?) AUUKIIIS SPECKS IH STRIBLII TON ANIl ALL MASS TOTALS.
J) ALL MASS rilTALS
Reproduced from
best available copy.
172
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LNILK iNnnh. ut rut-MKU unui f J.LL ] i-muLim n . un i
MENOQTrt . LIAT
ENFFR NAME OF MINTLO INPUT FILE 2 MENCIOTA2 , DftT
ENTER NAME OF EXAMS INPUT FILE .EXAMS. DAT
EXAMS. DAT
UAITING FOR EXAMS
TIME = 358t3.16
BEXAMS -- STOP
TTOOA — STOP
TIME 128.
TTOOB — STOP
sci;
LOGO
COMMAND NOT ALLOWED ACTIVE TASK
SCI>' AB
SCI.: LOGO
User FiSA UIC C220.7] TTOOI 22:41!59 7-JUN-83
22:41:59 END PDS FiSA TTOO:
BYE
173
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