Table Of ContentCONTRIBUTORS
OWEN P. BRICKER
KENNETH Y. CHEN
BERT A. EICH EN BERGER
CLIFFORD C. HACH
JOHN D. HEM
JAMES R. KRAMER
PAUL E. LARSON
H. E. TAYLOR
RICHARD D. VANOUS
WATER ANALYSIS
VOLUME I INORGANIC SPECIES,
PART 1
Edited by
ROGER A. MINEAR
Department of Civil Engineering
The University of Tennessee
Knoxville, Tennessee
LAWRENCE H. KEITH
Radian Corporation
Austin, Texas
ACADEMIC PRESS
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COPYRIGHT © 1982, BY ACADEMIC PRESS, INC.
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Library of Congress Cataloging in Publication Data
Main entry under title:
Water analysis.
Includes bibliographies and index.
Contents: v. 1. Inorganic Species, Part 1.
1. Water—Analysis. I. Minear, R. A.
II. Keith, Lawrence Η., Date.
QD142.W36 628.1'61 82-1755
ISBN 0-12-498301-4 (v.l AACR2
PRINTED IN THE UNITED STATES OF AMERICA
82 83 84 85 9 8 7 6 5 4 3 2 1
LIST OF CONTRIBUTORS
Numbers in parentheses indicate the pages on which the author's contributions begin.
OWEN P. BRICKER* (55) Maryland Geological Survey, Baltimore,
Maryland 21218
KENNETH Y. CHEN (1) University of Southern California, Environ
mental Engineering Program, Los Angeles, California 90007
BERT A. EICHENBERGER (1) University of Southern California, Envi
ronmental Engineering Program, Los Angeles, California 90007
CLIFFORD C. HACH (163) Hach Company, Loveland, Colorado 80537
JOHN D. HEM (137) U.S. Geological Survey, Menlo Park, California
94025
JAMES R. KRAMER (85) Department of Geology, McMaster Univer
sity, Hamilton, Ontario L8S 4MI, Canada
PAUL E. LARSON (163) Hach Company, Loveland, Colorado 80537
H. E. TAYLOR (235) U.S. Geological Survey, Water Resources Divi
sion, Arvada, Colorado 80002
RICHARD D. VANOUS (163) Hach Company, Loveland, Colorado
80537
* Present address: U.S. Geological Survey, Reston, Virginia 22092.
vii
PREFACE
This is the first of three volumes designed to present both the theoreti
cal and the practical aspects of understanding and determining the trace-
level components that are found in all natural, pristine, and polluted wa
ters. We have attempted to provide in a single source a collection of
detailed treatments on each of the important aspects necessary to such an
understanding. In doing so we have selected a cadre of distinguished
authors, from both the United States and abroad, to discuss each aspect
in a level of detail not generally presented for the individual topics.
The treatise separately considers the various inorganic and organic
components that occur in water. While this separation is traditional, it
does provide some distinct organizational advantages. This is important
because of the wide-ranging audience likely to be using these works. Both
practicing professionals and students in environmentally related disci
plines will find these volumes to be a useful reference source. This in
cludes biologists, chemists, environmental scientists, public and environ
mental health scientists, and the various engineering disciplines
(chemical, civil, sanitary, etc.). The scope and level of treatment of the
individual topics is necessarily variable, being dependent on the subject
matter and the particular author's judgment. But in each case the topics
are dealt with in far greater depth than the usually superficial treatment
found in conventional textbooks. Thus it is our intent that these volumes
will serve as a complete text on state-of-the-art treatments of this complex
subject.
Volume I is the first of two focusing on the inorganic constituents in
water. It first presents a background on the inorganic constituents found
in water. A general treatment of the sources of representative species
found in both natural waters and wastewaters is followed by a discussion
on the effects of hydrolysis, complexation, and dissolution in conjunction
with redox and pH in the environmental dynamics of these species. This
sets the stage for a detailed discussion of these topics in the succeeding
two chapters.
The fourth chapter deals with conductance, a general measure of solu
tion ionic content. Both reaction rates and equilibrium composition in
water are regulated by ionic strengths so that solution behavior is ulti
mately tied to the nature and the total amount of dissolved species, which,
in turn, can be measured by conductance. Although conductance mea
surements are thus a widely applied parameter in aqueous measurements,
they do have their limits of use and interpretation. So the underlying
ix
χ Preface
theory is presented with the practical applications to guide the reader in
the proper use and interpretation of conductance data. This same format
will be found in most of the chapters throughout this work.
Turbidity, like conductance, is an indirect or surrogate measurement of
some of the components comprising that complex material we refer to as
"water." However, while conductance measurements pertain to charged,
dissolved species in water, turbidity measurements relate to undissolved,
suspended matter in water. This relationship is not a simple one, and the
in-depth treatment of light scattering theory principles in Chapter 5 is
intended to give the reader a sufficient understanding of the complexity of
turbidimetric responses so that application and interpretation of turbidi-
metric data can be applied intelligently.
Chapter 6 concludes this volume with a survey of general water quality
analytical procedures used for measuring individual inorganic species.
This chapter, in turn, sets the stage for Volume II, which is organized by
specific analytical methods and instruments for individual inorganic
species.
ORIGIN AND NATURE OF SELECTED
INORGANIC CONSTITUENTS IN
NATURAL WATERS
Bert A. Eichenberger and Kenneth Y. Chen
University of Southern California
Environmental Engineering Program
Los Angeles, California
I. Introduction 1
II. Chemical Reactions of Inorganic Species
in Aqueous Solution 2
A. Hydrolysis Reactions 2
B. Complexation with Inorganic Ligands 3
C. Complexation with Organic Ligands 3
D. Eh-pH Effects 4
III. Origin and Nature of Trace Inorganic
Constituents in Natural Waters 5
A. Metallic Species 5
B. Nonmetallic Species 38
References 44
I. INTRODUCTION
Inorganic species enter natural waters from a variety of sources. The
weathering of rocks and soils directly exposed to surface waters is usually
the largest natural source. Atmospheric fallout of particulate matter from
natural sources as well as from anthropogenic inputs, which include the
combustion of fossil fuels and material processing, can introduce rela
tively large quantities of inorganic species into natural-water systems.
Other anthropogenic inputs, including the discharging of various treated
and untreated liquid wastes to the receiving waters or the contamination
of the aquatic system through various construction, mining, lumbering, or
similar activities, can introduce large quantities of inorganic constituents
into natural waters. Degradation products of plant and animal tissue also
contribute small amounts of inorganic species to receiving waters.
Natural-water systems are highly complex electrolyte solutions in con
tact with a variety of inorganic and organic solids. Inorganic constituents
WATER ANALYSIS, VOL I -|
Copyright © 1982 by Academic Press, Inc.
All rights of reproduction in any form reserved.
ISBN 0-12-498301-4
2 Bert A. Eichenberger and Kenneth Y. Chen
from whatever source, once having entered natural-water systems, are
subject to the complex abiotic and biological interactions occurring in the
natural environment. In general, the origin and nature of major inorganic
species of carbon, nitrogen, sulfur, phosphorus, and chloride are de
scribed in great detail in most water-chemistry textbooks [1-3]; therefore,
in this chapter, these species will be discussed only in terms of their effect
on the presence of trace inorganic species, especially trace metals.
The solubility of minerals and coordination compounds of inorganic
ions is considered the most important phenomenon responsible for the
presence of trace elements in natural waters. The significant parameters
controlling the solubility of mineral phases are the pH and redox of the
solution, the type and concentration of complexing inorganic and organic
ligands and chelating agents, and the oxidation state of the mineral com
ponents. For ease of discussion, inorganic constituents are divided into
two groups: (1) metallic species and (2) nonmetallic species.
II. CHEMICAL REACTIONS OF INORGANIC SPECIES IN
AQUEOUS SOLUTION
The possible interactions occurring between metallic species and other
solution species are described, followed by a discussion of individual
metals.
A. Hydrolysis Reactions
Soluble hydrolysis products are particularly important in natural-water
systems in which trace concentrations of metal ions are present. The low
cation concentrations and the relatively wide range of pH over which
hydroxo and oxo complexes can be present can significantly affect the
chemical behavior of these metals [1].
The chemical species and oxidation states of the hydrolysis products
formed in aquatic systems can control many aspects of chemical behav
ior, e.g., (1) the adsorption of soluble species on particulates; (2) the
tendency of the metal species to coagulate colloidal particles and to form
precipitates; (3) the solubility of the controlling solid phase; (4) the extent
to which the ions can be complexed in solution; and (5) the oxidation or
reduction of the metal species to another valence state.
Stumm and Morgan [1] established two general rules for the hydrolysis
of cations: (1) the tendency of metal ions solutions to hydrolyze increases
with dilution and with increasing pH, and (2) the fraction of polynuclear
complexes in a solution decreases on dilution. The establishment of hy-
1 Inorganic Species 3
drolysis equilibria is frequently very fast, as long as the hydrolysis species
are simple. Polynuclear species are formed rather slowly. Many of these
polynuclear hydroxo complexes may be considered as kinetic intermedi
ates in the formation of insoluble metal oxides and are thus thermodynam-
ically unstable. The slow kinetics of condensation reactions is one of the
reasons that wide variance is often observed in the literature for the values
of hydrolysis constants [1].
B. Complexation with Inorganic Ligands
Complexation of trace elements by both inorganic and organic ligands
plays a significant role in affecting the migration of metal species through
natural aquatic systems. The most important inorganic complexing
species are bicarbonate, chloride, fluoride, hydroxide, sulfate and sulfide,
and phosphate.
Quite commonly the concentrations of anionic species in water are
sufficient to form complexes with the metal ions by replacing coordinated
water from aquo complexes. The reactions between metal ions and inor
ganic ligands yield various soluble and insoluble species depending on the
metal concentration, ligand concentration, and pH. The formation of in
soluble ligand complexes can greatly affect the distribution of metals be
tween the solid and aqueous phases by the formation of metal-ligand
precipitates. This is particularly true at the sediment-water interface of
natural systems where concentration and redox gradients are usually the
largest [4].
Most inorganic ligands of significance in natural waters tend to be pres
ent at concentrations many orders of magnitude greater than the trace-
metal ions they tend to complex. Each metal ion has a speciation in simple
aqueous solutions that is dependent upon the stability of the hydrolysis
products and the tendency of the metal ion to form complexes with other
inorganic ligands. The pH at which hydrolysis products are formed in any
significant amount is dependent upon the concentration of the ligand com
peting with OH~ for the metal ion [5]. A systematic treatment of the status
of metal ions in aqueous solutions is presented elsewhere [1].
C. Complexation with Organic Ligands
Significant concentrations of natural and synthetic complexing ligands
are present in many aquatic systems. Concentrations of dissolved organic
matter in natural waters usually range from 0.1 to 10 mg/L. The upper
concentration is reached in polluted lakes, streams, and estuaries. The
lower concentration is more typically encountered in unpolluted and
4 Bert A. Eichenberger and Kenneth Y. Chen
nonproductive freshwater systems [1]. The reported organic matter in
natural systems includes compounds such as amino acids, humic acid,
fulvic acid, fatty acids, citric acid, polysaccharides, organic phosphorous
compounds, aromatic compounds containing alcohol and carboxyl func
tional groups, and porphyrins which contain donor atoms suitable for
complex formation [1, 4-6].
The term metal-organic describes structural configurations in which
the metal is bonded to organic matter by way of (1) carbon atoms yielding
organometallic compounds; (2) carboxyl groups producing salts of organic
acids; (3) electron-donating atoms, Ο, N, S, P, etc., forming coordination
complexes; or (4) π-electron-donating arrangements (olefinic bonds,
aromatic rings, etc.). Porphyrin-type materials are widespread in living
systems. Porphyrin complexes isolated from various organisms include
chlorophylls, iron porphyrins, vitamin B , and many other compounds in
12
which the tetrapyrole system is bonded to copper, cadmium, manganese,
and zinc [5].
It has been noted by many investigators that organic ligands can play a
major role in natural waters by complexing trace-metal ions and keeping
them in solution. In addition to this important effect on the speciation of
metal ions, organic ligands are likely to mediate large interactions (compe
tition) among those metal ions [6].
Recent determinations of trace-metal-natural-organic-matter stability
constants have confirmed that humic substances are significant complex
ing agents in natural waters [7-9]. Despite this fact, progress has been
slow in the development of the chemical structure and properties of these
compounds due to their complexity. The functional groups of humic acid
are predominantly carboxylic, phenolic, and alcohol, which are important
with respect to metal coordination [7, 10].
D. Eh-pH Effects
The pH and E of the water system can control solubilization or
h
agglomeration and therefore subsequent sedimentation of the metal
species. The pH also affects the bonding of metals to particulates because
hydrogen ions can influence adsorption and ion exchange by competing
for active sites, modifying the sites, or changing the degree of protolysis of
the sorbing material [1, 11].
The hydrous oxides of iron and manganese are important in the aquatic
environment because changes in redox potential, acidity, and ligand con
centrations can lead to the formation or dissolution of these colloidal
particulates. As the pH decreases, the surface charges and attractive
forces become diminished and metal ions sorbed to hydrous oxides are
