United States Office of Water _ , .
Environmental Protection Regulations and Standards P.lUary 130 /
Agency Criteria and Standards Divisior. SCD# 9
Washington DC 20460
Water
SEDIMENT QUALITY CRITERIA FOR METALS: III.
REVIEW OF DATA ON COMPLEXATION OF TRACE
METALS BY PARTICULATE ORGANIC CARBON
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053&
SEDIMENT QUALITY CRITERIA FOR METALS:
III REVIEW OF DATA ON THE' COMPLEXATION OF TRACE METALS BY
PARTICULATE ORGANIC CARBON
Work Assignment 56, Task 4
January 1987
Prepared by:
Herbert E. Allen and Jean M. Mazzacone
Drexel University
Philadelphia, PA
for:
U.S. Environmental Protection Agency
' Criteria and Standards Division
Washington, O.C.
Submitted by:
BATTELLE
Washington Environmental Program Office
Washington, D.C.
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ABSTRACT
The approach to developing sediment quality criteria for trace metals is
based on predicting the activity of the metal ion in interstitial water of
the sediment and relating the concentration of the metal 1on to the toxic
level of the metal ion inferred from the water quality criteria for the metal.
To predict the activity of the metal In the interstitial water, it is necessary
to model the sorption of the metal to the sediment using a surface complexation
adsorption model that relates the adsorption to the trace metal ion activity
in solution and not to the total metal concentration. The resulting sediment
quality criteria for trace metals will be based on the net adsorption of the
metal to the three major sorption phases in sediment—iron oxides, manganese
oxides, and reactive particulate organic carbon. This report is a review of
the organic carbon adsorption literature.
Organic matter in soil can be classified as humic or nonhumic substances.
The humic substances are in turn composed of three main groups-fulvie acid,
humic acid, and humin. These groups are distinguished by their respective
solubilities in dilute acid and dilute base. Abundant evidence exists for
the complexation of trace metal cations with soil organic matter, mainly humic,
and fulvic acids. Two methods have been used to evaluate the binding of metal
ions to humic substances. The first and most common method is to consider
the humic molecule as a ligand and the metal ion as the central atom. In the
second method, the humic molecule is considered to act as the central atom
and the metal cations as ligands. Several investigators have attempted to
measure the stability constants for the binding of trace metals to humic
substances; however, the constants appear to be dependent on the pH, metal
concentrations, amount of organic matter, temperature, and ionic strength.
Therefore, these constants are conditional constants.
An alternative approach to modeling the complexation of trace metals to
humic substances is to consider that the substances are polyelectrolytes.
Marinsky and colleagues used this method to overcome the difficulties in the
determination' of stability constants.
Tables of the published stability constants for trace metal complexation
by humic acids and fulvic acids are included in the appendix of this report.
The stability constants in the tables are used to evaluate the percent of
i i i
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CONTENTS
ABSTRACT
INTRODUCTION
BACKGROUND
EXTRACTION OF ORGANIC CARBON FROM SEDIMENTS
PURIFICATION OF HUMIC SUBSTANCES
CHARACTERIZATION OF HUMIC SUBSTANCES
TRACE METAL BINDING TO HUMIC SUBSTANCES: PROBLEMS
OF POLYELECTROLYTES
TRACE METAL BINDING TO HUMIC SUBSTANCES:
PROBLEMS OF NONUNIFORMITY
PUBLISHED TRACE METAL-HUMIC SUBSTANCE STABILITY CONSTANTS
EVALUATION OF STABILITY CONSTANTS
CONCLUSIONS
REFERENCES
APPENDIX "
APPENDIX REFERENCES '
v
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TABLES
A.l Reagents used for Extraction of Organic Constituents from Soil A-l
A.2 Methods for Characterizing Humic and Fulvic Acids . a-2
A.3 Elemental Analysis of Humic and Fulvic Acids a-3
A.4 Oxygen-Containing Functional Groups in Humic Substances .... A-4
A.5 Major Oxygen-Containing Functional Groups in Humic Substances . A-5
A.6 Phenolics and n-Fatty Acids Released by Hydrolysis of Humic
and Fulvic Acid with 2 N NaOH at 170°C for 3 Hr A-6
A.7 Effect of Fulvic Acid Concentration on Cadmium-Fulvic
Acid Conditional Stability Constants . . . . A-7
A.8 Stability Constants of Cu^-Fulvic Acid Complexes
at pH 3.5 and 5.0
A.9 Effect of pH on Cadmium-Fulvic Acid Conditional Stability
Constants
A.10 Effect of Ionic Strength (m) on the Stability Constants
of Metal-Fulvic Acid Complexes A-10
A.11 Experimental Methods A-11
A.12 Organic Complexation Reactions ..... A-12
A.13 Stability Constants for Al(III)-Fulvic Acid and
Al(III)-Humic Acid Complexes A-13
A.14 Stability Constants for Ca(II)-Fulvie Acid Complexes A-14
A.15 Stability Constants for Cd(II)-Fulvie Acid Complexes A-15
A.16 Stability Constants for Cd(II)-Humic Acid Complexes A-16
A.17 Stability Constants for Co(II)-Fulvie Acid and
Co(II)-Humic Acid Complexes A-18
A.18 Stability Constants for Cu(II)-Fulvie Acid Complexes A-19
A.19 Stability Constants for Cu(II)-Humic Acid Complexes A-20
A.20 Stability Constants for Fe(II)-Fulvie Acid Complexes A-22
A.21 Stability Constants for Fe(III)-Fulvic Acid and
Fe(III)-Humic Acid Complexes A-23
vi i
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INTRODUCTION
The U.S. Environmental Protection Agency, Criteria and Standards Division,
has initiated an effort to develop sediment quality criteria for nonpolar
organic contaminants and trace metals. These sediment quality criteria will
be used in conjunction with water quality criteria to protect U.S. freshwater
and saltwater bodies and their uses. The approach chosen for developing
sediment quality criteria for trace metals 1s based on predicting the activity
of the metal ion in the interstitial water of the sediment and relating this
concentration to the toxic level of the metal ion inferred from the water
quality criteria for the metal (Jenne et al. 1986). Thus, the sediment quality
criteria will be tied to the water quality criteria. The activity of the
metal ion in the interstitial water is predicted from the adsorption of the
metal to sediment using a surface complexation adsorption model. The surface
complexation model relates the adsorption to the trace metal ion activity in
solution and not to the total metal concentration, thus avoiding the limitations
of the more classical distribution constant and adsorption isotherm approaches.
To predict the adsorption of the metal on the sediment, the adsorption constants
for the metals on the three major sorption phases in the sediment—iron oxides,
manganese oxides, and reactive particulate organic carbon—and the quantity of
each of these sorption phases in the sediment must be determined.
This report is a review of the organic carbon adsorption literature. It
is one in a fou)—part series of reports reviewing the available literature on
sorption constants for metals on iron oxides^ ^ and manganese oxides^), anc[
extraction methods for estimating the quantities of each of the sorption phases
(a) Jenne, E. A. 1987. spHiment Quality Criteria for Met.als: IV. Review of
Surface Complexation and Acir|itv Constants for Modelling Adsornt.ion of Parlm-i
and Zinc onto Iron Oxides. Submitted by Battelle, Washington Environmental
Programs Office, Washington, D.C. to the U.S. Environmental Protection Agency,
Criteria and Standards Division.
(b) DiToro, D. M., and B. Wu. 1986. Sediment Quality Criteria for Metal<;•
V. Review of nata for Determining the Intrinsic Adsorption Constants for
Manganese Dioxide. HydroQual Co., Inc. Submitted by Battelle, Washington
Environmental Program Office, Washington, D.C. to the U.S. Environmental
Protection Agency, Criteria and Standards Division.
1
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BACKGROUND
Organic matter can be classified as two basic types, humic substances and
nonhumic substances. Humic substances are amorphous, acidic, and polydisperse
(i.e., exhibit a wide range in molecular sizes) with molecular weights ranging
from several hundreds to tens of thousands (Schnitzer and Khan 1972). These
substances are composed of three main groups that are distinguished by their
solubilities 1n dilute acid and dilute base. The fulvic acid fraction (FA)
is soluble in dilute base and dilute acid. The humic acid fraction (HA) is
soluble in dilute base but is insoluble in acid solution. The humic fraction
is insoluble in both acid and base solutions (see Figure 1).
The nonhumic substances have specific and identifiable chemical
characteristics and include such substances as carbohydrates, proteins, amino
acids, fats, and resins. These nonhumic substances are easily decomposed by
microorganisms and thus have a relatively short residence time. Therefore,
soil or sediment
extract witn dilute alkali
under N2 or neutral Na4P207
solution
insoluble
Humin
soluble
acidify
precipitate
HA
soluble
FA
FIGURF 1. Extraction and Fractionation of Humic Material
(Schnitzer 1976, p. 90)
3
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phase may have altered the sediment surface and thus the adsorptlve behavior
of the organic particulate matter. The evidence, however, suggests that
particulate organic matter is important in trace metal sorption.
5
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CHARACTERIZATION OF HUMIC SUBSTANCFS
Methods for characterizing humlc substances fall Into two general categories,
the degradatlve and the nondegradative. The different methods
for each category can be found In Table A.2 (Schnitzer 1976).
Elemental analysis of humlc substances (Table A.3) has shown that the major
constituents are carbon and oxygen (Schnitzer 1976). Functional group analysis
of humlc acid and fulvic acid from different soils can be found 1n Table A.4
(Schnitzer 1976) and Table A.5 (Schnitzer and Khan 1972). The carboxyl and
phenolic functional groups are believed to be involved 1n trace metal binding.
These tables show that fulvic acids have a greater oxygen content, whereas
humic acids have a greater carbon content. Also in fulvic acids, a larger
amount of the oxygen that 1s present is tied up in -OH, -C00H, and -C=0
functional groups than in these same functional groups in the humic acid.
Finally, fulvic acid is more acidic than humic acid.
Degradative methods for humic substance characterization have produced
products that consist mainly of aliphatic cjrboxylic acids, benzene carboxylic
acids, and phenolic acids. Other degradative products Include n-alkanes,
substituted furans, and dialkyl phthalates. Some of the compounds produced
from these degradative products are shown in Table A.6 and in Figures 3-5
(Schnitzer 1976).
X-ray analysis and electron microscopy of fulvic acid (Kodama and Schnitzer
1967) has shown that this substance consists of a network of condensed aromatic
rings perforated by holes that can trap organic and inorganic compounds.
Combining this information and that gathered through other methods of
degradative and nondegradative characterization, several general structures
of humic and fulvic acids were proposed: Figure 6 (Stevenson 1982), Figure 7
(Stevenson 1982), Figure 8 (Stevenson 1982), Figure 9 (Schnitzer and Khan
1972), and Figure 10 (Stevenson 1982).
In summary, humic substances are complex mixtures whose exact composition
varies as a function of the source and method of isolation.
9
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PURIFICATION 0F HUMTC SUBSTANCES
Once the humlc materials are extracted from the sediment and divided into
the different fractions (Figure 1), the fractions need to be purified to remove
organic and Inorganic Impurities. To remove ash from humlc acid (HA), Khan
(1971) used dilute solutions of HC1/HF and dlalyzed against distilled water
in the presence of a hydrogen 1on exchange resin. Gascho and Stevenson (1968)
alternately dlalyzed the HA against 0.3N HF and 0.02M Na^^Oj. Dormaar et
al. (1970) used successive precipitations with mineral acid followed by passage
through an 1on exchange resin to purify the HA fraction.
Organic impurities, such as lipids, can be removed from the HA with ether
or an alcohol/benzene mixture. Hydrolysis with mineral acids, gel filtration,
and phenol extraction can be used to remove carbohydrates and proteins from
HA (Stevenson 1982).
For fulvic acid (FA), inorganic impurities can be removed by the use of
cation exchange resins. Organic impurities can be removed by the process
shown in Figure 2 (Stevenson 1982).
7
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CHARACTERIZATION OF HUMIC SUBSTANCFS
Methods for characterizing humlc substances fall Into two general categories,
the degradatlve and the nondegradative. The different methods
for each category can be found In Table A.2 (Schnitzer 1976).
Elemental analysis of humlc substances (Table A.3) has shown that the major
constituents are carbon and oxygen (Schnitzer 1976). Functional group analysis
of humlc acid and fulvic acid from different soils can be found 1n Table A.4
(Schnitzer 1976) and Table A.5 (Schnitzer and Khan 1972). The carboxyl and
phenolic functional groups are believed to be involved 1n trace metal binding.
These tables show that fulvic acids have a greater oxygen content, whereas
humic acids have a greater carbon content. Also in fulvic acids, a larger
amount of the oxygen that 1s present is tied up in -OH, -C00H, and -C=0
functional groups than in these same functional groups in the humic acid.
Finally, fulvic acid is more acidic than humic acid.
Degradative methods for humic substance characterization have produced
products that consist mainly of aliphatic cjrboxylic acids, benzene carboxylic
acids, and phenolic acids. Other degradative products Include n-alkanes,
substituted furans, and dialkyl phthalates. Some of the compounds produced
from these degradative products are shown in Table A.6 and in Figures 3-5
(Schnitzer 1976).
X-ray analysis and electron microscopy of fulvic acid (Kodama and Schnitzer
1967) has shown that this substance consists of a network of condensed aromatic
rings perforated by holes that can trap organic and inorganic compounds.
Combining this information and that gathered through other methods of
degradative and nondegradative characterization, several general structures
of humic and fulvic acids were proposed: Figure 6 (Stevenson 1982), Figure 7
(Stevenson 1982), Figure 8 (Stevenson 1982), Figure 9 (Schnitzer and Khan
1972), and Figure 10 (Stevenson 1982).
In summary, humic substances are complex mixtures whose exact composition
varies as a function of the source and method of isolation.
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COjH CO,H CO|H CO.H
OH ON OH OH
CO,H CO|H OH
CO,M CO,M CO»H
FIGURE 5. Major Phenolic Degradation Products (Schnitzer 1976, p. 96)
FIGURE 6. Dragunov's Structure of Humic Acid [Kononova shows
(1) an aromatic ring of the d1- and trihydroxybenzene type,
part of which has the double linkage of a qui none group;
(2) nitrogen in cyclic forms; (3) nitrogen in peripheral
chains; and (4) carbohydrate residue (Stevenson 1982,
P. 258)]
11
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OH OH p
C—OH-
OH C*®,
OH "» ^
FIGURE 9. Structure of Fulvic Acid (Schnitzer and Khan 1972)
OH COOH CH2OH
hooc^y^ ch2 c^ci^ch3
HOOC^yv^CH, 0 ""CH2-COOH
OOOHOH xCH r'CHOH
0 COOH
FIGURF in. Model Structure of Fulvic Acid According to Buffie
(Stevenson 1982, p. 261)
13
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In the second method, the humic molecule is considered to act as the central
atom, and the metal cations act as "ligands" permitting formation of metal-
humic acid complexes with multiple metals (i.e., MjA complexes where j > 1).
Investigators attempted to measure the strength of binding of trace metals to
humic substances or, in other words, the stability constants. The stability
constants, K, as defined by Equations (1) and (2) are
However, problems occur when determining stability constants. Stability
constants, K, for the binding of trace metals to humic substances, measured
under different experimental conditions, have different values. Stability
constants are conditional constants because they appear to be dependent on
such experimental conditions as pH, metal concentration, amount of organic
matter, temperature, and ionic strength. For example, Saar and Weber (1979),
in a study on soil and water fulvic acids that was previously prepared by
Weber and Wilson (1975), found that the stability constants for fulvic-cadmium
complexes decreased as the concentration of fulvic acid increased (Table A.7).
Saar and Weber (1979) concluded that the decrease in the stability constant
was a result of the conformational changes that occurred when the concentration
of.fulvic acid was increased. The conformational changes resulted in a blocking
of some potential binding sites. Schnitzer and Skinner (1966) found that the
stability constant was not dependent on the fulvic acid concentration for
copper-fulvic complexes (Table A.8).
Saar and Weber (1979) also investigated the effect of'pH on the value of
the stability constants for cadmium-fulvie acid complexes and found that the
kj - [ma+]/[m+2][a"]
k2 = [MA2]/[MA+][A"]
(3a)
(3b)
and for the overall reaction:
2A~ + M+2 <-+ MA2
K = kxk2 - [MA2]/[M+2][A~]2
(4)
(5)
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Finally, Sposito et al. (1979), in a study on complexation of copper by
fulvlc acid extracted from sewage sludge, found through Scatchard Plots that
+2
as the ratio of Cu to FA increased (increased metal loading), the stability
constant decreased. Bresnahan et al. (1978), in a study of copper-fulvic
complexes, also found this relationship to be true. This decrease in the
stability constant was attributed to the presence of different types of binding
sites in the humic molecule. Therefore, because stability constant values
are dependent on pH, ionic strength, and metal and FA concentrations, most of
the reported stability constants can only be considered conditional constants.
Stability constants measured under different experimental conditions vary
significantly for several reasons. Humic substances are polyelectrolytes
that range in apparent molecular weights, solubilities, and acid strengths
(Marinsky et al. 1983). These humic substances are heterogeneous in composition
and thus have different functional groups in different chemical environments.
As a result, the binding of trace metals at one site will affect the binding
of trace metals at other sites. Aggregation of humic substances may also
affect the number of sites available for binding. For polyelectrolytes, the
surface charge on the humic molecule will vary with the degree of dissociation
of the humic molecule, the ionic medium in which the molecule is present, and
the amount of metal binding (Marinsky and Reddy 1984a,b). In previous work,
these factors were not incorporated into the expression for the stability
constant; consequently, stability constant values vary widely. A goal is to
develop a model that will account for these conditions and also allow for the
prediction of trace metal availability in aquatic systems.
Another factor that complicates the interpretation of data on metal-humic
binding is that at least two types of metal ion-humic reactions were identified
(Gamble et al. 1985): an electrostatic binding resulting from the charged
surface on the humic material and an inner-sphere complex formation (inner
sphere meaning the humic molecule ligand replaces water molecules bound to
the hydrated metal cation) including chelation (more than one binding site on
the humic molecule is bound to a single metal ion).
Marinsky and others tried to overcome these difficulties in the determination
of stability constants. When considering the nature of humic substances,
note that there are two general types (Gamble et al. 1-985): a small low
molecular weight polydisperse polymer (i.e., a fulvic acid), and a higher
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7.6
7.0
pK 6.0
S.0
4.6
I
FTfillRF 12. Potentiometric Titration of Polymethacrylic Acid
(Gamble et al. 1985, p. 381)
FTfiURF n. Potentiometric Titrations of Sphagnum Peat
(Gamble et al. 1985, p. 382)
. « tlO^MKCL
10 M KCL \
/ I X
—-
Jlvshi KCL
" | I lO^M KCL
!?—
1 :
19
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1 n
where pK (HA)= the intrinsic acid dissociation constant of the
repeating functional group 7 of the humic acid gel
^Na(g) = activity coefficient of Na+ in the gel
F = the electrostatic free energy of the system
psi(a) = the potential at the gel surface.
The apparent stability constant can be expressed in terms of experimentally
measurable quantities:
pKapp(HAb - pH(s) - pNa(s) - l°g{CNa(g) + A/Vg} - log {«/(l-«)} (10)
where ^Na(g) = concentration of sodium ion in the humic acid gel which
is accessible through base titration
Vg = volume of the gel
A = dissociated humic acid
If a plot of pKapp(HA)7 versus a is constructed and the line is extrapolated
to « = 0, the value of the y intercept is pKint(HA)7, and the intrinsic acid
dissociation constant of the repeating functional unit 7. The y intercept is
pKint(HA)7 because at low ionic strength there will be negligible NaX imbibement
and at zero charge on the gel surface the deviations from ideality will vanish.
The distribution of a metal cation, M , and a neutral salt (i.e., Na )
between two phases can be determined by the same method used to determine the
acidity constant (Gamble et al. 1985). The expression for the equilibrium
+ +z
distribution of Na and the metal cation of interest, M , between a gel and
an aqueous phase can be written as
pM+z(g) - pM+z(s) = zpNa+(g) -zpNa+(s) (11)
Expansion of Equation (11) and inclusion of pKapp(MA)n(z-n)7 (apparent or
conditional stability constant of the metal humic complex) gives
pM+z(s) - zpNa(s) - z log{CNa^ + A/Vg} -n log{(A/Vg)/(Mb/Vg)}
= pKapP(MA)n(z-n)7 (12)
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If one or the other species Is dominant, this analysis will result in a constant
value for Dl, because the deviation terms 1n the numerator and denominator
exp(-2£ ps1(a)/KT), will cancel out 1f the charge arises exclusively from the
three-dimensionally situated sites of the gel matrix.
If both species are formed the expressions for Dl and D2 would be:
02 - [jJ1nt(MA2)7 /{/>1nt(HA)}2] ~ [(Va){£int(MA+)7}/(A){jJ1nt(HA)7}2] (18)
and
Dl ¦ W,nt(MA+)7/W,nt(HA)7}2] + [(A)Wtnt(HA2)7}/(Vg){JJ,nt(HA)-,}2] (j9)
By plotting D2 versus Vg/A and extrapolating to Vg/A - 0, the y Intercept would
be equal to /Jlnl(MA2)7/{jJ1nt(HA)7}z. By plotting Dl versus A/V and
extrapolating to A/Va = 0, the y intercept would be equal to
/S1nt(MA+)7/£^1nt(HA)7}2.
23
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where mSM 1s the molal concentration of the chelated sites, m^ Is the molal
concentration of the protonated sites, and mSH is the molal concentration of
the free chelation sites. Similar relationships can be written for each of
the components. The mole fraction of free chelation sites, ^SH, for the 1th
component 1n the whole mixture is
* mS1H^Cs
where the material balance summed over all m^ 1s equal to m^. By including
expressions for the mole fraction 1n Equation (23), for the material balance,
and for the law of mass action; the average equilibrium constant function (K)
for the whole mixture is expressed as
K= ^Xsh *Ki exp (-AGe1/RT)(^SH)1 (24)
The summation in Equation (24) may be replaced by an integral if K approximates
a continuous function. A continuous function 1s expected because of the large
numbers of individual K-j functions and because the electrostatic Gibbs energy
will be an increasing function of the amount of electrostatic charge (free
chelation' sites, SH) on the molecules and aggregates.
Shuman et al. (1983) evaluated metal binding to humic substances by an
"affinity spectrum" technique, as suggested by Hunston (1975). The binding
relationship of bound metal to total ligand, 7, is rewritten for multiple
sites as
m
7 = I (n1 iq [M])/(l + K1 [M]) (25)
i = 1
where 1 is the 1th class with ni sites and with binding constant, . The
total number of sites, n0, when summed over all classes is
m
no s f "i (26)
25
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linger and Allen^ have applied the Shuman affinity model to the binding
of metals by sediments; they found that the data does not resemble normal or
gaussian probability densities for humic substances, as suggested by Posner
(1966) and Perdue and Lytle (1983b), but portrayed a positive skewness toward
the higher log K values, linger and All en ^ found that the data followed a
Maxwell-Boltzman distribution instead.
(a) Unger, M. T., and H. E. Allen. 1986. "Distribution Model of Metal Binding
to Natural Sediments." Drexel University. (Submitted for Publication)
(b) Unger, M. T., and H. E. Allen. 1986. "Distribution Model of Metal Binding
to Natural Sediments." Drexel University. (Submitted for Publication)
27
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and Yoshida 1978). Data in Table A.16, appendix reference 16 (linger 1984)
compared with data in Table A.16, appendix reference 14 (Allen et al. 1982)
show that log K values for Grand River bulk sediment and organic fraction
measured by different experimental methods, but under comparable conditions
were within an order of magnitude (log K = 7.14 for organic fraction appendix
reference 16, compared to 6.15 and 7.01 for appendix reference 14)
Stability constants for copper-humic acid complexes were measured under
the same experimental conditions by five different experimental methods (Table
A.19). For four out of the five methods, the log K values were within
experimental error: 6.54, 6.61, 6.72, 6.80 for experimental methods 5, 4, 16r
and 8, respectively (Tuschall and Brezonik 1983; Tuschall 1983). The anodic
stripping voltametry (ASV) method gave different log K values, probably
resulting from the sorption of ligand onto the surface of the electrode.
Therefore, it appears that the experimental method is not the major factor
that results in the reported range in K values for metal humic acid complexes.
As with Cd-humic acid complexes, the log K of Cu-humic acid (Table A.19) and
Zn-humic acid complexes (Table A.28) increases as the pH increases. The data
in Table A.19 (Adhikari et al. 1977) and (Tan et-al. 1971) and Table A.28
indicate that log K is not highly dependent on humic acid concentration-. The
data in Table A.19 also indicate that there are different binding sites on the
humic acid molecule and that these sites have different K values (Tuschall and
Brezonik 1983; Tuschall 1983).
For the binding of zinc to soil humic acids [Table A.28 (Matsuda and Ito
1970)] and sediments (linger 1984), the log K values appear to be dependent on
the soil sample (range of log K values is 4.20 to 10.33) but did not appear
to be dependent on the sediment used (range in log K values is 7.67 to 8.27).
Table A.28 also shows that log K values are independent of pH over the range
3.5 to 5.5 for Zn(II) complexes. However, most studies have shown metal-humic
acid complexation to be highly pH dependent.
In summary, most of the data indicate that as pH increases, log K increases.
The value of K appears to be dependent on the origin of the sample in some
cases, yet, in other cases, it is not. Experimental method is not a major
factor in the variability in log K values. Finally, the dependence of log K
on ligand concentration cannot be ascertained from the data.
29
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EVALUATION OF STABILITY CONSTANTS
The data in Tables A.16, A.19, and A.28 were carefully evaluated to determine
the percent of cadmium, copper, or zinc that would be bound to humic acid at
three different pH values (Tables A.29-A.31). Some of the data in Tables A.16,
A.19, and A.28 were not included in Tables A.29-A.31. For example, the data
in Table A.16 (Van de Meent et al. 1981) were omitted because only the binding
of cadmium to the suspended sediment as a whole and not just to the humic
acid present in the sediment, was measured. The data of Guy and Chakrabarti
(1979) in Tables A.16, A.19, and A.28 were omitted because Malcolm (R. Malcolm,
U.S. Geological Survey, Personal Communication, 1985) has indicated that Aldrich
humic acid is structurally very different from natural soil or sediment humic
acid. The data of Alberts and Giesy (1983), Shuman and Cromer (1979), and
Buffie et al. (1977) in Table A.19 were omitted because they dealt with binding
of metals to aquatic humic acid, which has also been shown by Malcolm to be
different from soil or sediment humic acid. The data in Tan et al. (1971) in
Tables A.19 and A.28 were omitted because it is not known if the sample chosen
is similar in properties to soil or sediment humic acid. Finally, the data
in Matsuda and Ito (1970) in Table A.28 were not used because of incomplete
data; the j values were not given.
The percent metal bound was calculated by the following method. First,
the degree of dissociation, a, of the humic acid was calculated. This value
is pH dependent. The following equation was used to determine a at a specific
pH:
pH = 5.05 - 1.93log{(l-«)/oc} (31)
This equation was determined by Stevenson (1976) from the curve that described
the titration of a Leonardite humic acid with base (Figure 14).
If the reaction of metal with humic acid is represented by
M + L ML (32)
then the stability constant would be
31
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Therefore, the ratio of bound metal to free metal, [ML]/[M], can be determined
from the conditional stability constant, Onditional, and the concentration
of ligand, CL.
To compute the ratio of bound to free metal, a humic acid concentration
needs to be chosen. A typical humic acid concentration is 5 mg/L (Laxen 1983),
and a typical humic acid molecular weight is 5000 Daltons (Schnitzer and Khan
1972). Therefore, the total concentration of undissociated ligand used in
the calculations is 1x10~6M. Further, rearrangement of Equation (35) yields
[M] - [ML]/Kcondlt1onalCL (36)
and substitution into Equation (37),
[ML] + [M] = MT
(37)
results in Equation (38)
[ML] ~ [ML]/(Kcond1t1onalCL) - MT (38)
[ML](1 + l/(Kcond1t10na1CL)) = MT
where My is the concentration of total metal. Therefore, the concentration
of bound ligand is
[ML] = MT/{1 ~ l/(KcondjtionalCL>} (39)
The percent metal bound is {100 x ([ML]/MT)}. Substitution of Equation (39)
into this expression gives the following equation:
% Metal Bound = 100 x (1 + I/Conditional^}"1 (40)
According to some references at a concentration of 0.005 g/L of humic acids,
appreciable binding of the metal by the humic material is predicted. When a
higher humic concentration (e.g., the 5 g/L level that is more typical of
sediment-water systems is considered) the predicted extent of binding is very
high.
33
-------
CONCLUSIONS
Data available to quantify the extent of metal partitioning between the
aqueous phase and the sediment-bound humlc substances 1s insufficient. Most
of the available literature constants do not account for the effects of hydrogen
ions and different electrolytes on metal sorption by reactive particulate
organic carbon.
The polyelectrolyte model appears to provide adsorption constants that are
compatible with the surface complexatlon constants for inorganic adsorbents.
Establishing sediment quality criteria for trace metals, using the approach
of Jenne et al. (1986) requires the experimental development of a data base
of complexatlon constants for trace metals with the reactive organic carbon
on the sediments. These complexatlon constants must be determined for a number
of oxic sediments representative of those sediments found in streams and lakes.
35
-------
Jenne, E. A., D. M. DiToro, H. E. Allen and C. S. Zarba. 1986. "An Activity-
Based Model for Developing Sediment Criteria for Metals: Part I. A New
Approach." In Proceeding of the International Conference of Chemicals in the
Environment, eds. J. N. Lester, R. Perry, and R. M. Sterritt. 1-3 July 1986,
Lisbon, Portugal.
Khalid, R. A., R. P. Gambrell and W. H. Patrick Jr. 1981. "Chemical
Availability of Cadmium 1n Mississippi River Sediment." J. Environ. Qua!.
10(4):523-528.
Khan, S. U. 1971. "Distribution and Characteristics of Organic Matter
Extracted from the Black Solonetzlc and Black Chernozemlc Soils of Alberta:
The Humic Acid Fraction." Soil Sci. 112(6):401-409.
Kodama, H., and M. Schnltzer. 1967. "X-ray Studies of Fulvic Acid, a Soil
Humic Compound." Fuel 46(2):87-94.
Laxen, D. P. H. 1983. "Cadmium Adsorption in Freshwaters - A Quantitative
Appraisal of the Literature." Science of the Total Environment. 30:129-146.
Lion, L. W., R. S. Altmann and J. 0. Leckie 1982. "Trace-Metal Adsorption
Characteristics of Estuarine Particulate Matter: Evaluation of Contributions
of Fe/Mn Oxide and Organic Surface Coatings." Environ. Sci. Techno!.
16(10):660-666.
Marinsky, J. A. 1972. "Equations for the Evaluation of Formation Constants
of Complexed Ion Species 1n Cross!inked and Linear Polyelectrolye Systems."
In Ion Exchange and Solent Fxtraction. Vol. 4, eds. J. A. Marinsky and Y.
Marcus, pp. 227-243, Marcel Dekker, New York.
Marinsky, J. A., S. Gupta and P. Schindler. 1982a. "The Interaction of Cu(II)
Ion with Humic Acid." .1- Colloid Interface Sci. 89(2) :401-411.
Marinsky, J. A., S. Gupta and P. Schindler. 1982b. "A Unified Physicochemical
Description of the Equilibria Encountered in Humic Acid Gels." J. Colloid
Interface Sri. 89(2):412-426.
Marinsky, J. A., F. G. Lin and K. Chung. 1983. "A Simple Method for
Classification of the Physical State of Colloidal and Particulate Suspensions
Encountered in Practice." .1- Phvs. Chem. 87:3139-3145.
J. A. Marinsky and Y. Merle. 1984. "The Intrinsic Dissociation Constant of
Weakly Acidic Cation-Exchange Gels." Talanta. 31(3):199-204.
Marinsky, J. A., and M. M. Reddy. 1984a. "Proton and Metal Ion Binding to
Natural Organic Polyelectrolytes—I. Studies with Synthetic Model Compounds."
Org. Geochem1 7(3/4):207-214.
Marinsky, J. A., and M. M. Reddy. 1984b. "Proton and Metal Ion Binding to
Natural Organic Polyelectrolytes-~II. Preliminary Investigation with a Peat
and a Humic Acid." Org. Geochem. 7(3/4):215-221.
37
-------
Schnitzer, M.f and S. I. M. Skinner. 1966. "Organo-Metallic Interactions in
Soils: 5. Stability Constants of Cu++-, Fe++-, and Zn++- Fulvic Acid
Complexes." Soil Sci. 102(6):361-365.
Shuman, M. S., B. J. Collins, P. J. Fitzgerald and D. L. Olson. 1983.
"Distribution of Stability Constants and Dissociation Rate Constants Among
Binding Sites on Estuarine Copper-Organic Complexes: Rotated Disk Electrode
Studies and An Affinity Spectrum Analysis of Ion Selective Electrode and
Photometric Data." In Aquatic and Terrestrial Humic Materials, eds. R. F.
Christman, and E. T. Gjessing, pp. 349-370. Ann Arbor Science, Ann Arbor,
Michigan.
Shuman, M. S., and J. L. Cromer. 1979 "Copper Association with Aquatic Fulvic
and Humic Acids. Estimation of Conditional Formation Constants with a
Titrimetric Anodic Stripping Voltammetry Procedure." Env. Sci. Technol.
13(5):543-545.
Spiteller, M. 1985. "Extraction of Soil Organic Matter by Supercritical
Fluids." Org. Geochem. 8(1):111-113.
Sposito, G. , K. M. Holtzclaw and C. S. LeVesque-Madore. 1979. "Cupric Ion
Complexation by Fulvic Acid Extracted from Sewage Sludge-Soil Mixtures."
Soi 1 Sci - W. Am. J. 43:1148-1155.
Stevenson, F. J. 1976. "Stability Constants of Cu+2, Pb+2, and Cd+2f Complexes
with Humic Acids." Soil Sci. Soc. Am. J. 40:665-672.
Stevenson, F. J. 1982. Humus Chemistry Genesis. Composition. Reaction?;.
Wiley-Interscience, New York.
Takamatsu, T.r and T. Yoshida. 1978. "Determination of Stability Constants
of Metal-Humic Acid Complexes by Potentiometric Titration and Ion Selective
Electrodes." Soil Sci. 125(6):377-386.
Tan, K. H., I. D. King and H. D. Morris. 1971. "Complex Reactions of Zinc
With Organic Matter Extracted from Sewage Sludge." Soil Sci. Soc. Amer. Proc.
35:748-752.
Tuschall, J. R. Jr. 1983. "Application of Continuous-Flow Ultrafiltration
and Competing Ligand/Differential Spectrophotometry For Measurement of Heavy
Metal Complexation By Dissolved Organic Matter." Anal. Chim. Acta. 149:47-58.
Tuschall, R. R., and P. L. Brezonik. 1983. "Complexation of Heavy Metals By
Aquatic Humus: A Comparative Study of Five Analytical Methods." In Aauatir
and Terrestrial Humic Materials, eds. R. F. Christman and E. T. Gjessing, pp.
275-294. Ann Arbor Science, Ann Arbor, Michigan.
Unger, M. T. 1984. Sorption of Cadmium and Zinc nntn Operationally Defined
Natural Solid/Solution Interfaces. Ph.D. Dissertation, Illinois Institute of
Technology, Chicago.
39
-------
APPENDIX
REPORT TABLES
-------
APPENDIX
REPORT TABLES
Table.A.1. Reagents used for Extraction of Organic Constituents from Soil
(Stevenson 1982, p. 37)
Type of Material
Extractant
Organic Matter
Extracted
(%)
Humic substancesa
Strong bases
NaOH
Na2CC>3
Neutral salts
Na4P2°7'NaF
organic acid salts
Organic chelates
Acetylacetone
Cupferron
8-hydroxyquinoline
Formic acid (HCOOH)
Acetone/H^O/HCI solvent
To 80%
To 30%
To 30%
To 30%
To 30%
To 55%
To 20%
Hydroiyzable compounds
1. Amino acids, amino sugars
2. Sugars
Polysaccharides
Clay-bound biochemicals
"Free" biochemicals (amino
acids, sugars)
Fats, waxes, resins
Hot 6 N HCI
Hot 1N H2S04
NaOH,HCOOH,hot water
HF
H20, 80% alcohol,
ammonium acetate
Usual "tat" solvents
25-45%
5-25%
<5%
5-50%
1%
2-6%
a Considerably higher amounts of organic matter can be extracted from
Spodosol B horizons with most reagents.
A-l
-------
TABLE A.3. Elemental Analysis of Humic and Fulvic Acids
(Schnitzer 1976, p. 91)
% dry, ash free wt
Element HA FA
C 50-60 40-50
H 4-6 4-6
N 2-6 <1-3
S 0-2 0-2
O 30-35 44-50
A-3
-------
TABLE A.5. Major Oxygen-Containing Functional Groups in Humic Substances
(meq/g) (Schnitzer and Khan 1972, p. 38)
Total
Acidity
Carboxyl
Phenolic
OH
Alcoholic
OH
Carbonyl
Metho:
Soil HA's
6.6
4.5
2.1
2.8
4.4
0.3
8.7
3.0
5.7
3.5
1.8
-
5.7
1.5
4.2
2.8
0.9
-
10.2
4.7
5.5
0.2
5.2
-
8.2
4.7
3.6
-
3.1
0.3
Coal ha
7.3
4.4
2.9
-
-
1.7
Snil FA'S
14.2
8.5
5.7
3.4
1.7
12.4
9.1
3.3
3.6
3.1
0.5
11.8
9.1
2.7
4.9
1.1
0.3
Soil Humins
5.9 3.8 2.1 - 4.8 0.4
5.0 2.6 2.4 - 5.7 0.3
A-5
-------
TABLE A.7. Effect of Fulvic Acid Concentration on Cadmium-Fulvie
Acid Conditional Stability Constants (Saar and Weber 1979,
p. 1265)
Water FA Soil FA
x104Ma K x 10*3 x104Mb K x 10"3
0.28
8.8
0.30
29
0.56
6.5
0.61
24
1.06
2.5
1.3
18
3.18
4.4
2.4
13
4.1
14
5.6
12
titrations done at pH 7.0 in 0.1 M KNO3
^Titrations done at pH in 0.1 M KNO3
A-7
-------
K x 10"3
PH
Water
Soil
Fulvic
Fulvic
Acid
Acid
4.0
1.4
1.7
5.0
3.0
6.3
6.0
4.8
12
7.0
8.1
21
8.0
12
43
a) All titrations have fulvic acid concentrations of 5 to
6x10"4 M and 0.1 M KN03 supporting electrolyte at 25 C.
A-9
-------
TABLE A.11. Experimental Methods
Numerical Experimental
Code Method
1
Anodic Stripping Voltametry (ASV)
2
AAa- Vary Sediment Concentration
3
AA- Vary Metal Concentration
4
Competing Ligand
5
Continuous Ultrafiltration
6
Continuous Variation
7
Differential Pulse Anodic Stripping Voltametry(DPAS)
8
Fluorescence
9
Fluorescence Quenching
10
Gel Filtration
11
Ion Exchange
12
Ion Exchange-AA
13
Ion Exchange-DPAS
14
Ion Exchange-Scintillation Counting
15
Ion Exchange-Spectrophotometric
16
Ion Selective Electrode (ISE)
17
Liquid Scintillation Counting
18
Metal Titration-AA
19
Potentiometric Titration-Conventional
20
Potentiometric Titration-Constant pH
21
Potentiometric Titration-ISE
22
Stopped Flow Spectrometry
23
Titrimetric-ASV
a) AA=Atomic Absorption Spectroscopy
A-ll
-------
TABLE A.13. Stability Constants for Al(III)-Fulvic Acid and
Al(III)-Humic Acid Complexes
*
f-
u>
Sample
Concentration
Temp
dH
|i
tog K
K Units
ExDerimental Method
Reaction
Armadale Podzol(l)
3.7
0 IN KCI
3.7
L/Moles
6
3
1
1
Armadale PodzolMI
1.70
O.tN KCI
37
U Moles
15
3
1
1
Armadale Podzot(n
2.35 .
0.00
53
L/Moles
6
3
1
1
Armadale Podzotyll
.2J1_
0 15N KCI
2.8
L/Moles
6
3
1
1
ChinsuraWesl Benqal<2)
2 0320 x10-4 M
30 C
4.0
11
3
2
Chinsura West Benoal<21
4 0640 XlO-4 M
30 C
4 0
11
3
2
Chinsura Wesl Bengal<2)
6 0960 xlO—4 M
30 C
4.0
11
3
2
Chinsura Wesl Benqal(2)
8 1200 xtO-4 M
30 C
4.0
11
3
2
Chinsura Wesl Benpal(2)
101600 xlO—4 M
30 C
4 0
11
3
2
Chinsun-Wsst BwaaK?)
30 C
4 0
3.15*
(L/Molesll
11
3
0.90
2
ChinsuraWesl Benaal(2
300
5 5
3.38
(L/Molps)|
11
3
0 90
2
Broiler House Litter(3i
7 xlO—5 M
3,5
Q.1NKPL-
2.93
(L/Molesli
12
3
0.60
3
14 X10-5-M
3 5
O IN KCI
2.81
(L/Moles)j
12
3
0 60
3
21 >10-$ M
3 5
0 IN KCI
2.93
(L/Molesli
12
3
0 60
3
28 *10-5 M
3 5
0 IN KCI
2.9
(L/Moles)j
12
3
0 60
3
9 6 xi0-5 M
5 5
0 IN KCI
3 99
(L/Moles)|
12
3
0.83
3
18 2 xlO—5 M
5 5
0 IN KCI
4.01
(L/Moles)j
12
3
0 83
3
28 8 xlO—5 M
55
0 IN KCI
3.99
(L/Moles)
12
3
0.83
3
38.4 XlO -5 M
5.5
0 1N KC
3 93
(L/Moles)
12
3
0 83
3
48 0 xlO-5 M
5.5
0 IN KC
3.98
(L/MolesM
12
3
0 83
3
0* Fulvic Acid
(2) Humic Acid
(3) Organic Matter Extra
(t (Both HA and FA1
'Average Value
Inferences in Tables A. 15 - A. 34 are cited by number and can be found in numerical
order at the end of this appendix.
-------
TABLE A.15. Stability Constants for Cd(II)-Fulvic Acid Complexes
Sample
Concentration
Temp
BH
H
bgk2
K UllilS
Experimental Method
_Qcaclioa_
Befeience
Sewape Sludge
2 *10-3 M
25 C
_5.0_
4 0
0 1M KCI04
3 04 L/Moles
2.27 L/Moles
2 3
L/Moles
21
i
6
Water Fulvic Acid
5 6 *10-4 M
25 C
0 IM KCI
3 15
L/Moles
21
2
7
Waler Fulvic Acid
5 6 *10-4 M
25 C
5,0
0 1M KCI
3.48
L/Moles
21
2
7
Wator Fulvic Acid
5 6 X IP 4 M
C
6 0
0 IM KCI
3.68
L/Moles
21
2
7
Walor Fulvic Acid
5-6 *10-4 M
25 C
7.0
0 1M KCI
3 01
L/Moles
21
2
7
Water Fulvic Acid
5 6 *10-4 M
25 C
9 0
0 IM KCI
4.08
L/Moles
21
2
7
Soil Fulvic Acid
5 6 xlO—4 M
25 C
4.0
0 IM KCI
3 23
L/Moles
?1
2
7
Soil Fulvic Acid
5 6 *10-4 M
25 C
5 0
0 IM KCI
3.8
L/Moles
21
2
7
Soil Fulvic Acid
5 6 *10-4 M
25 C
6.0
0 IM KCI
4 08
L/Moles
21
2
7
Soil Fulvic Acid
5 6 x1&-4 M
25 C
7 0
0 IM KCI
4.32
L/Moles
21
2
7
Soil Fulvic Acid
5 6 *10—4 M
25 C
8 0
0 IM KCI
4 63
L/Moles
21
2
7
Waler Fulvic Acid
0 28 *10-4 M
25 C
7 0
0 1MKNO3
3 84
L/Moles
10
1
8
Waler Fulvic Add
0 56 *10-4 M
25 Q
7,0
01MKNQ3
3 81
L/Moles
10
1
8
Water Fulvic Add
1 06 xlO—4 M
25 C
7 Q
0 1MKHO3
3.40
L/Moles
10
1
8
Waler Fulvic Acid
Soil Fulvic Acid
0 30 *10-4 M
25 C
6 0
0 1MKNO3
3 64
L/Moles
10
1
8
O IM KN03
4.46
L/Moles
10
8
Soil Fulvic Acid
061 xlO—4 M
25 C
e 0
0 IM KN03
4 38
L/Moles
10
8
Soil Fulvic Acid
1 31 *10—4 M
25 C
01MKNO3
4 26
L/Moles
10
1
8
Soil Fulvic Acid
Soil Fulvic Acid
4 1 xlO—4 M
25 0
25 C
6.0
0.IMKNO3
4 11
L/Moles
10
1
8
6 0
0 1MKNO3
4 15
L/Moles
10
1
8
Soil Fulvic Acid
5 6 xlO-4 M
25 C
6.0
0.1MKNQ3
4 08
L/Moles
10
1
8
-------
TABLE A.16. Continued
Sample
Concentration
Temp
oil
loa kl
loa k2
LoaK
K Units
ExDerimenlal Method
Iteacli&n
Reteffinj
Giand River Sediment
Unliaclionaled
20 C
7 5
5.59
L/Moles
2
i
14
Oroanic
20 C
7.5
7 01
1 /Moles
2
i
14
Grand River Sediment
i
14
Unlracltonaled
20 C
7 5
6 06
L/Moles
3
t
14
Oroanic
20 C
7 5
6 15
L/Moles
3
i
14
Swains Mills
2 0 *10-5 M
6 5
5.72
L/Moles
23
i
15
Chanel HMI
2 9 *10—6 M
5 7
4 87
L/Moles
23
i
15
2 9 *10-6 M
6 0
4.99
I/Moles
23
i
15
2 9 *10-fi M
6 5
5.15
L/Moles
23
i
15
2.9 *10—fi M
7 0
5.2
L/Moles
23
i
15
I ake Waccamaw
9 1 *10-5 M
6 5
4.51
L/Moles
23
i
15
Black Lake
12 6 *10—5 M
6 5
4.81
L/Moles
23
i
15
Sediment Fractions:
Des Plainea-
Bulk
25 C
7 5
5.90
L/Moles
17
16
Oiidi2afales
25 C
7.5
8 02
L/Moles
17
t
16
Grand River-
1 /Moles
17
16
Buh
25 C
7.5
5 93
L/Moles
17
L
t
16
Oiidi?abtos
25 C
7 5
7 14
1 /Moles
17
1 6
Kan7aU-
L/Moles
17
1
1 6
Butk
25 C
7 5
7.08
1 /Moles
17
1
16
Oxidizahlas
25 C
7 5
8 91
L/Moles
17
i
1 6
1. Michkian
L/Moles
17
l
I 6
Bulk
25 C
7 5
6.17
L/Moles
i
1 6
Oxidizahtea
25 C
7 5
B.04
L/Moles
17
1
1 6
Wahash
L/Moles
17
1
1 6
Bulk
25 C
7.5
6 75
L/Moles
17
l
16
Oxidizablea
25 C
7.5
9.08
L/Moles
17
1
1 6
Averaoe Value
L/Moles
17
1
16
Bulk
25 C
7 5
6 36
L/Moles
17
t
16
Oxidizables
25 C
7 5
8 24
L/Moles
17
1
16
Suhiianum Deal
.15 g/20ml
6.65(4)
L/Moles
17
4
1
17
1 n See reference lor
lescriolion ol sample
<21 Cd Water Complex
3S
I3> Weighted lor value
ol binding capacity 141
loa K inl
-------
TABLE A.18. Stability Constants for Cu(II)-Fulvic Acid Complexes
Concentration
Temp
tit
M
loa kl
loa k2
loa K
K Units
Expnfimcnlal Method
_ HuiicLioiL
i
Reference
!
SewcNJo Sliidae
2 *10—3 M
25 C
JLQ
8.0
0 1 M KCI04
3 88 L/Moles
2 11 (./Moles
2.30
L/Moles
21
1
e 1
LuHe Celyn Wales
20 C
0 02
8 00 L/Moles
8 05 L/Moles
8 42
L/Moles
IP
1
8 !
Soil Fulvic Acid
4.0
0 1 M KN03
5 60 L/Moles
3 95 L/Moles
4 36
L/Moles
21
1
18
Soil Fulvic Acid
5.0
0 1 M KN03
6 00 L/Moles
4 08 L/Moles
4 6
L/Moles
21
»
18
Soil Fulvic Acid
6 0
0 1 M KN03
6 30 L/Moles
3 78 L/Molos
4.2
L/Moles
21
1
18
Waler Fulvic Add
4 0
0 1 M KN03
5 48 L/Moles
4.00 L/Moles
4 49
L/Moles
21
1
19
Waler Fulvic Acid
4.7
0 1 MKN03
6 00 L/Moles
3 85 L/Moles
4.39
L/Moles
21
19
Water FuMc Add
5 0
0 1 MKN03
5 95 L/Moles
3 70 L/Moles
4.08
L/Moles
21
19
Waler Fulvic Add
6 0
0 1 M KN03
6.11 L/Moles
3 85 L/Moles
4.37
L/Moles
21
3
19
Annadala Podfol
3 *10—4 M
24 -0 1 C
3 5
0 IN KCI
5.78
(L/Motesli
15
1,50
19
Aimadala Podzol
A *10—4 M
24 -0 1 C
3.5
0 1N KCI
5 79
(L/Moles ti
15
3
1 59
19
Aimadala Podzol
0 *10—4 M
24 -0.1 C
3 5
0 IN KCI
5.75
a/Moles)l
15
3
3
J
19
Armadale Podzol
12 *10—4 M
24 -0 1 C
3.5
0 IN KCI
5 78
(L/Molesli
15
J^5SL_
19
Aimadala Podzol
15 *10—4 M
24 -O.I C
3 5
0 IN KCI
5 80
H/Molesli
15
3
.u§a_
19
Aifnariala PocJjol
24 -0 1 C
0 IN KCI
5.78*
(L/Moles)i
15
3
1.50
19
Armadale Podzol
12 *10-4 M
24 -0 1 C
5.0
0 IN KCI
8 67
(L/Molesti
15
2 Q0
19
Aimadala Podzol
1.5 *10-4 M
24 -0.1 C
5.0
0 IN KCI
8 87
(L/Moles VI
15
3
2 00
19
Aimadala Podzol
18 *10-4 M
24 -0 1 C
5.0
0 IN KCI
8 66
(L/Molesti
15
3
2 0 Q
19
Armadale Podxol
2 1 *10—4 M
24 -0 1 C
5 0
0 IN KCI
8 76
IL/Molesli
15
3
2 QQ
19
Armadale Podzol
2 4 *10—4 M
24 -0 1 C
5 0
0 IN KCI
8.7
(L/Molesti
15
3
2 00
19
Aimadate-Efidiol
Aimadala Podzol
24 -0 1 C"
o
5.0
0 IN KCI
8 67
(L/Molesti
15
3
2 00
19
0 1N KCI
8.69*
(L/MplesM
15
3
2.00
19 .
Aimadala Podzol
2 24 *10—6 M
25 C
7 6
0 01M KN03
7 82
L/Moles 1
13
1
20
Aimadala Podzol
3 0
0 10M KCI
3.3
L/Moles
9
3
1
1
Aimadala Podzol
5.0
0 10M KCI
4.0
L/Moles
6
3
1
1
Afiii^dat? PotJjol
3 0
0 10M KCI
3.3
L/Moles
15
3
1
1
Aimadala Podzol
5 0
0 10M KCI
4 0
L/Moles
15
3
1
1
Amiadalo Podzol
3 0
0 00
4.7
L/Moles
9
3
1
1
Aimadala Podzol
3 0
0 15
2 6
L/Moles
6
3
1
1
Black 1 ako-NC
«5ma/l
5,89
UMoies
23
1
21
Black 1 ake-NC
30ma/l
5.43
L/Moles
23
1
21
Black Lake-NC
60ma/l
5.54
L/Moles
23
1
21
Soil Fulvic Acid
2 8 uM
5 0
0 1M KN03
5 78
. UMelss
7
1
22
Soil fulvic Acfcl
4 8 uM
5 0
01MKNO3
5.90
L/Moles
7
22
Soil Fulvic Acid
6.7 uM
5 0
0IMKNO3
5 70
L/Moles
7
1
22
Soil fulvic Acid
5 0
01MKNO3
5.78*
L/Moles
7
22
Soil Fulvic Acid
2 8 uM
6 0
0 1MKNO3
5 70
MMfiles
7
1
2?
Soil Fulvic Acid
4 8 uM
6.0
0 1M KN03
5.48
L/Moles
1
22
Soil Fulvic Acid
6 7 uM
6 0
0 1MKNO3
5.00
L/Moles
7
_... 1
22
Soil Fulvic Acid
5 0
0 1M KN03
5.48*
L/Moles
7
1
22
Soil Fulvic Acid
22 1 uM
0 |MKN03
4.68
L/Molfs
9
23
Soil Fulvic Acid
19 7 uM
6 0
0 1MKNO3
5 03
L/Moles
9
1
23
Soil Fulvic Acid
196 uM
7.0
0 1M KN03
5,45
L/Moles
9
23
'Avoraoe Value
-------
TABLED A .19. Continued
Sample
Basin Swamp:
.Id.
Concentration
Iemp.
(4L
tog hi
Jag Js2_
JogJL
jpsiimuolaLMellifiil
IkatUon
0 0 025
5,8 xlQ-6 M_
0 026 0.125
5 8 *10-6 M
_6.2i_
6.2
QJfitiKNQl
-4JU.
1-/Moles
0.1 ON KN03
5 30
0.126-0.4
5.8 X10-6JJ-
fiJQM KN03
00.025
2.1 HIP—5 M
0.026 0.125
2.1 xlQ—6 M
0126-0.4
2.1 X10-6 M-
0 0 025
1.4 Hi0—6 M
0 026 0 125
1.4 XlO—6 M
0 ION KNQ3
0ION KNQ3
-&JUL
l/Moles
i_ iLlSti KNQ3
X!L
0.1 ON KN03
-2.42-
L/Moles
16
flJON KN03
6.85
0 12604
1.4 X10-6 M
00.025
1.2 XlO 6 M
6.25
6.25_
-L/Melea
_Lfi_
0J0MKNQ3
6.26
L/Molea
_Lfi_
0.1 ON KN03
0.0260.125
1.2 XlO—6 M_
Q.10N KN03
L/Moles
0.126 0.4
1.2 X10-6 M
6.25
0.1QN KNQ3
5 56
L/Molea
00.025
1.3 nlO-6 M
6.25_
0 ION KNQ3
0.026 0.125
1.3 XlO—6 M
6,25
0.10N KNQ3
6 72
L/Molea
M
0.126 0.4
1.3 xlO—6 M
6.2 5_
0.10NKNQ3
5,54
L/Molea
£.E. US Watets(2)
-5JL
6.52-0 45
4.89-0.82
5.76
-16.
Bioitef House Litlei(3)
14 KlO—6 M_
JL5L
0 1NKCI
7.15
(L/Moloa)!
12.
1.44
JL1NKQL
7.14
(L/Moles)|
AZ
Bipitef House Llller(3)
1SL2js1
28.8 xlO-6 M
MKC1_
0.1NKC1
OlNKCI
7.19
(L/Moles)|
J2_
7.15
IL/Molesll
12
JLltLKGL
_8.26_
_fi.2Z_
_(LZMfil£tsU-
_L2_
(LZMflleJSli
_12_
Bioii
Bioiler Housa Liller<3\
48.0 »1Q—6 M
5.5
HlJtiKCL
JL1NKCI
8.24
8.28
(L/MolesH
(L/Moles)|
_1SL
-12.
1.44_
JL44_
1.44
JL66_
1£L_
-L6&-
Sample l-Pond Water
.2§_£L
_fiJL
0.1M NaN03
_5JL
9.5
Sill
Sphagnum Peal
25_C
0.1M NaNQ3
15 q/200ml
4.6
(L/Moles)l
ilfi_
10.1
iL/Moles)i
_lfi_
7.65(41
-------
TABLE A.21. Stability Constants for Fe(III)-Fulvic Acid and
Fe( 111)-Humic Acid Complexes
Samole
Concentration
Terno.
oH
ii
loo K
K Units
Experimental Molhod
Roue lion
i
Rslerer
Aimadala Podzaldt
1.70
0.1N KCI
6.1
(L/Molesll
6
3
1
1
Armadiila Podzol(1l
1.70
0 00
7 6
fl /Moleslj
6
3
1
1
Armadale Podzof/D
1.70
0 15N KCI
5.4
fL/Molasli
6
3
1
1
Bh Horizon-Princa Edward Island/11
3 *10-5 M
25 0 C
1.0
0.10 N NaCI04
4.45
L/Moles
22
1 /
27
Bh Horizon-Prince Edward Island/ M
3 *10-5 M
25 0 C
15
0.10 N NaCI04
4.18
L/Moles
22
1
27
Bh Horizon Prince Edward Island/ M
3 *10-5 M
25 0 C
2.5
0.10 N NaCID4
4.18
L/Molus
22
1
27
Chinsura West Benaal(2)
30 C
4.0
1 1
3
1
2
4J5fi4fi_xl£L=4-M_
6 0960 *10-4 M
3QJG
30 C
-4J1
4 .0
1 1
3
1
2
1 1
3
1
2
Chinsura-Wesl Banoal/2)
Cliinsura-Wesl Benaal/2)
6.1280 xtO-4 M
30 C
4.0
1 1
3
1
2
10.1600 *10-4 M
30 C
4.0
1 1
3
1
2
Chinstira Wesl Benaal<2)
30 C
4.0
3 56*
(L/Moleal|
1 1
3
1
2
Chinsura West Benaal/2)
30 C
5.5
3.87
(L/Molesli
1 1
3
1
2
ft) Fulvic Acid
(21 llumic Acid
'Averaae Value
-------
TABLE A.23. Stability Constants for Mn(II)-Fulvic Acid Complexes
Samole
Concentration
Temp.
oH
(i
log K
K Units
Experimental Method
Reaction
1
Reference
Armadale Podzol
0.6 x10—3 M
24- 0.1 C
3.5
0.1N KCI
1.46
l
12
3
1.10
5
Armadale Podzol
3.0 xlO—3 M
24- 0.1 C
5 0
0.1N KCI
3.8
(L/MolasV)
12
3
1.10
5
Armadale Podzol
4.5 xlO—3 M
24- 0.1 C
5.0
0.1N KCI
3.73
(L/Moles)|
12
3
1.10
5
Armadale Podzol
5.5 X10—3 M
24- 0.1 C
5.0
0.1N KCI
3.78
(L/Moles1|
12
3
1.10
5
Armadale Podzol
24- 0.1 C
5.0
0.1N KCI
3.78*
(L/Moles)|
12
3
1.10
5
Armadale Podzol
3.0
0.1N KCI
2.1
IL/Molesll
6
3
1
Armadale Podzol
5.0
0.1N KCI
3.7
(L/Molesl)
6
3
1
1
Armadale Podzol
3.0
0.1N KCI
2.2
(L/Molestl
15
3
1
1
Armadale Podzol
5.0
0.1N KCI
3.7
(L/MolesU
15
3
1
1
Armadale Podzai
3.0
0.00
2.9
(L/Moleat|
6
3
1
1
Armadale Podzol
3.0
0.15
1.7
(L/Moles)|
6
3
1
1
*Averaae Value
-------
TABLE
A. 25. Stability
Constants for Pb(II)
-Fulvic Acid Complexes
Sainolo
Concentration
TemD
PM
M
toa kl
loo k2
loa K
K Unite
Experimental Method
Reaction
i
Reference
Sewaae Sludoe
2 *10-3 M
25 C
5
0 1M KCK34
4 22 L/Moles
2 62 L/Moles
2.77
l/Moles
21
1
6
Armadale Podzol
0 6 x10—3 M
24 -0 1 C
3.5
0 IN KCI
3.1
(L/Moles)|
12
3
0.75
5
Afmadale Podzol
12 xlO—3 M
24 -0 1 C
3 5
0 IN KCI
3 07
(L/Moles li
12
3
0 75
5
Aimadale Podzol
1 B *10—3 M
24 -0 1 C
3.5
0 IN KCI
3 09
(L/Moles)}
12
3
0 75
5
Afmadale Podzol
2 4 xlO—3 M
24 -0 1 C
3.5
0 IN KCI
3.09
I L/Moles ti
12
3
0.75
5
Afmadale Podzol
30 xlO—3 M
l 24 -0 1 C
3 5
0 IN KCI
3.08
(L/Moles)j
12
3
0.75
5
Aimadale Podzol
3.09*
-------
TABLE A.27. Stability Constants for Zn(II)-Fulvic Acid Complexes
Sample
Concentration
Terra).
dH
n
k>a K
K Units
Experimental Method
Reaction
i
Relerence
Lake Celvn-Wales
20 C
8.00
0.02
5,14
L/Moles
10
1
8
Armadale Podzol
3.0 *10-4 M
24 -0.1 C
3.5
0.1 NKCI
1.72
(L/Moles)|
15
3
0.58
19
Armadale Podzol
6.0 xlO—4 M
24 -0.1 C
3-5
0.1 NKCI
1.74
(L/Molesll
15
3
0.58
19
Armadale Podzol
9.0 xlO—4 M
24 -0.1 C
3.5
0.1 N KCI
1.73
(L/Molesli
15
3
0.58
19
Armadale Podzol
12.0 x10—4 M
24 -0.1 C
3.5
0.1 N KCI
1.73
(L/Moles)}
15
3
0.58
19
Armadale Podzol
15.0 x10—4 M
24 -0.1 C
3.5
0.1 N KCI
1.74
(L/Moles)}
15
3
0.58
19
Armadale Podzol
24 -0.1 C
3.5
0.1 N KCI
1.73'
(L/Moles)f
15
3
0.58
19
Armadale Podzol
3.0 x10—4 M
24 -0.1 C
5.0
0.1 N KCI
2.34
(L/Moles\)
15
3
0.56
19
Armadale Podzol
6.0 xlO—4 M
24 -0.1 C
5.0
0.1 N KCI
2.34
(L/Mo|#$)J .
15
3
0.56
19
Armadale Podzol
9.0 xlO—4 M
24 -0.1 C
5.0
0.1 N KCI
2.34
(L/Molesll
15
3
0.56
19
Armadale Podzol
12.0 x10—4 M
24 -0.1 C
5,Q
0.1 N KCI
2.34
(L/Molesif
15
3
0.56
19
Armadale Podzol
15.0 xlO—4 M
24 -0.1 C
5.0
0.1 N KCI
2,33
(L/Moleslf
15
3
0.56
19
Armadale Podzol
24 -0.1 C
5.0
0.1 NKCI
2.34*
(L/Moles\|
15
3
0.56
19
Armadale Podzol
3.0
0.1 N KCI
2,4
(L/Mo|es)i
6
3
1
1
Armadale Podzol
5.0
0.1 N KCI
3,7
(L/MolesH
6
3
1
1
Armadale Podzol
3.0
0.1 N KCI
2,2
(L/MolesM
15
3
1
1
Armadale Podzol
5.0
0.1 N KCI
3.G
(L/Moles^
15
3
1
1
Armadale Podzol
3.0
0.00
3.2
(L/Molestf
6
3
1
1
Armadale Podzol
3.0
0.15 N KCI
2
(L/Moles1|
6
3
1
1
Soils(1)-
32
Room
7
0.1N KCI
5.79
(L/Moles>|
14
3
not aiven
29
2
Room
7
0.1N KCI
4 62
(L/Molesli
14
3
not aiven
29
31
Room
7
0.1N KCI
7.49
fL/Moles>|
14
3
not aiven
29
12
Room
7
0.1N KCI
5.36
(L/Moles)}
14
3
not aiven
29
19
Room
7
0.1N KC|
(L/Moleslj
14
3
not aiven
29
38
Room
7
0.1N KCI
7.59
(L/Moles\|
14
3
not aiven
29
33
Room
7
0.1N KCI
4.53
(L/Molesli
14
3
not aiven
29
18
Room
7
0.1N KCI
6.5
(L/Molesli
14
3
not aiven
29
26
'
Room
7
0.1N KCI
9.3
(L/Molesli
14
3
not aiven
29
8
Room
7
0.1N KCI
8.34
(L/MolesM
14
3
not aiven
29
1
Room
7
0.1N KCI
6.65
(L/Molesli
14
3
not qiven
29
30
Room
7
0.1N KCI
8.2
(L/Moles)i
14
3
not aiven
29
25
Room
7
0.1N KCI
6.89
(L/Molesli
14
3
not aiven
29
3
Room
7
0.1N KCI
5.75
(L/Moles\i
14
3
not aiven
29
20
Room
7
0.IN KCI '
7.25
(L/MolesW
14
3
not aiven
29
4
Room
7
0.1N KCI
(L/Molesl|
14
3
not aiven
29
5
Room
7
0.1N KCI
:e,98
(UMoles)j
14
3
not aiven
29
39
Room
7
0.1N KCI
7.01
(L/Moles>|
14
3
not aiven
29
24
Room
7
0.1N KCI
5.85
/L/Moles^
14
3
not aiven
29
22
Room
7
0 IN KCI
(L/Moles)i
14
3
not qiven
29
-------
TABLE A.28. Stability Constants for Zn(II)-Huraic Acid Complexes
U)
Samole
Concenlialion
Temp.
Dll
u
k>a K
K Units
Experimental Method
Reaction
i
Reference
Aldrich
20fig/l
6.8
5.0Q
IVrnq HA
18
2
9
Yolo Clay loam
7.84 -39.2 nia
3.6
0 IN KCI
4.42
L/Moles
15
3
1
31
Yolo Clay loam
7.84 -39 2 mq
5.6
0.1N KCI
6-19
L/Moles
15
3
1
31
Yolo Clay loam
7.84 -39.2 mq
7.0
0.1N KCI
6.99
L/Moles
15
3
1
31
Chinsura-West Bengal
2.4880 xlO—4 M
30 C
4.0
1 1
3
2
4.9759 xlO—4 M
30 C
4.0
-
11
3
2
Chinsura-West Benaal
7.4637 xlO—4 M
30 C
4.0
1 1 *
3
2
Chinsura-West Benaal
9.9520 10—4 M
30 C
4.0
1 1
3
2
Chinsura-West Benaal
12 4395 *10—4 M
30 C
4.0
11
3
2
Chinsura-West Bengal
30 C
4.0
2.93*
/L/Moles)|
11
3
1.09
2
Chinsura-West Benaal
30 C
5.5
3.60
/L/Moles)}
1 1
3
1.09
2
Garden Peat/1)
20 C
8.00
0.02
4.93
L/Moles
10
1
8
Broiler House Litter/2)
14 xlO—6 M
3.5
0.1N KCI
$.32
/L/Moles)|
12
3
1.04
3
Broiler House Litter/21
21 X10-6 M
3.5
0,1N KQ
5.49
/L/Moles)|
12
3
1.04
3
Broiler House Litter/2)
28 xlO—6 M
3.5
0.1N KCI
5.43
(L/Molestj
12
3
1.04
3
Broiler House Litter/2)
35 xlO—6 M
3.5
0.1 N KCI
5.45
/L/Moles)j
12
3
1.04
3
Broiler House Litler/2)
42 xlO-6 M
3.5
0.1N KCI
3
3
56 xlO—6 M
35
O.'IN KCI
3
3
Broiler House Utter/2)
9 6 xlO—€ M
5.5
P IN KCI
5.75
(L/Molestj
12
3
1.06
3
Broiler House Litler/2)
19 2 xlO—6 M
5.5
0.1N KCI
5.72
/L/Moles))
12
3
1.06
3
Broiler House Litter/2)
28.8 xlO—6 M
5,5
Q,1N KCI
5.72
/L/Moles)}
12
3
1.06
3
Broiler House Litter/2)
38 4 x10-€ M
5,5
0.1N KCI
5,72
/L/Moles)j
12
3
1.06
3
BroNer House Litter/2)
48.0 xlO—6 M
5.5
0.1 N KCI
6-74
/L/Moles)}
12
3
1.06
3
Soil Samoles/3)-
32
Room
7
9,IN KCI
10.31
/L/Moles)j
14
3
not aiven
29
2
Room
7
9,IN KCI
7.74
-------
TARl F A.29. Percent Cadmium Bound by 0.005 g/L of Humic Acid
Reaction
Number (a)
1
1:1 complex
1
1
3
1:2 complex
4
1:2 complex
4
1:1 complex
Percent Cadmium Bound
PH
3
0.03
33
97
<.00001
<.00001
26
4
0.1
57
99
<.0001
<.0001
49
6
0.3
82
1 00
0.0007
0.0001
77
Reference
1 1
14
1 6
1 1
1 0
17
(a) Reactions given in Table A. 12.
A-33
-------
TABLE A.31. Percent Zinc Bound by 0.005 g/L of Humic Acid
Reaction Percent Zinc Bound Reference
Number (a) pH
(a) Reactions given in Table A. 12.
6
1 0.005 1 5 8
1 88 95 99 16
3 0.03 0.09 0.3 2
3 20 41 71 31
4 35 60 84 1 7
1:1 complex
A-35
-------
TABLE A.33. Log K Values for Copper-Humic Acid Complexes at
Specific pH Values
PH
K Units
Reference
3
4
6
1.00
1.44
1.98
L/g
32
2.07
2.31
2.60
L/g
2
2.41
2.85
3.39
L/g
24, 25
2.85
3.29
3.83
L/g
1 7
3.06
3.50
4.04
L/g
8
-2.03
-1.15
-0.07
L2/g2
1 0
-1.04
-0.17
0.91
L2/g2
32
A-37
-------
Table A.35. Chosen Stability Constants for Metals
pH
Metal 3 __i
Cd " 2.0 2.3 3.0
Cu 2.8 3.2 3.8
Zn 2.0 2.3 3.0
A-39
-------
13. van de Meent, D., A. Los, J. W. De Leeuw, P. A. Schenck and W. Salomons.
1981. "Stability Constants and Binding Capacities of Fractionated Suspended
Matter for Cadmium." Fnviron. Tech. Lett. 2:569-578.
14. Allen, H. E., M. T. Unger, I. Bertahas and C. Mlklosh. 1982. "Strength
of Metal Binding by Sediment Fractions." Thalassia Jugoslavia.
18(1-4)5123-134.
15. Shuman, M. S., and G. P. Woodward. 1977. "Stability Constants of
Copper-Organic Chelates in Aquatic Samples." Env. Sci. Techno!. 11(8):809-813.
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