Copper (EHC 200, 1998)

INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY

ENVIRONMENTAL HEALTH CRITERIA 200

COPPER

This report contains the collective views of an international group
of experts and does not necessarily represent the decisions or the
stated policy of the United Nations Environment Programme, the
International Labour Organisation, or the World Health
Organization.

First draft prepared by Dr C. Dameron and colleagues at the
National Research Centre for Environmental Toxicology, Australia,
and by Mr P.D. Howe, Institute of Terrestrial Ecology, Monks Wood,
United Kingdom

Published under the joint sponsorship of the United Nations
Environment Programme, the International Labour Organisation, and
the World Health Organization, and produced within the framework of
the Inter-Organization Programme for the Sound Management of
Chemicals.

World Health Organization
Geneva, 1998

The International Programme on Chemical Safety (IPCS),
established in 1980, is a joint venture of the United Nations
Environment Programme (UNEP), the International Labour Organisation
(ILO), and the World Health Organization (WHO). The overall
objectives of the IPCS are to establish the scientific basis for
assessment of the risk to human health and the environment from
exposure to chemicals, through international peer review processes,
as a prerequisite for the promotion of chemical safety, and to
provide technical assistance in strengthening national capacities
for the sound management of chemicals.

The Inter-Organization Programme for the Sound Management of
Chemicals (IOMC) was established in 1995 by UNEP, ILO, the Food and
Agriculture Organization of the United Nations, WHO, the United
Nations Industrial Development Organization, the United Nations
Institute for Training and Research, and the Organisation for
Economic Co-operation and Development (Participating
Organizations), following recommendations made by the 1992 UN
Conference on Environment and Development to strengthen cooperation
and increase coordination in the field of chemical safety. The
purpose of the IOMC is to promote coordination of the policies and
activities pursued by the Participating Organizations, jointly or
separately, to achieve the sound management of chemicals in
relation to human health and the environment.

WHO Library Cataloguing in Publication Data

Copper.

(Environmental health criteria ; 200)

1.Copper - adverse effects. 2.Copper - toxicity
3.Environmental exposure 4.Occupational exposure
I.International Programme on Chemical Safety II.Series

ISBN 92 4 157200 0 (NLM Classification: QV 65)
ISSN 0250-863X

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letters.

CONTENTS

ENVIRONMENTAL HEALTH CRITERIA FOR COPPER

1. SUMMARY AND CONCLUSIONS

1.1. Identity, physical and chemical properties
1.2. Analytical methods
1.3. Sources of human and environmental exposure
1.4. Environmental transport, distribution and transformation
1.5. Environmental levels and human exposure
1.6. Kinetics and metabolism in laboratory animals and humans
1.7. Effects on laboratory animals and in vitro test systems
1.8. Effects on humans
1.9. Effects on other organisms in the laboratory and field
1.10. Conclusions
1.10.1. Human health
1.10.2. Environmental effects

2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES AND ANALYTICAL
METHODS

2.1. Identity
2.2. Physical and chemical properties
2.3. Analytical methods
2.3.1. Sampling and sample preparation
2.3.1.1 Sampling
2.3.1.2 Separation and concentration
2.3.1.3 Sample preparation
2.3.1.4 "Clean" techniques for measurement
of ultratrace copper levels
2.3.2. Detection and measurement
2.3.2.1 Gravimetric and colorimetric methods
2.3.2.2 Atomic absorption, emission and mass
spectrometry methods
2.3.2.3 Specialized methodologies
2.4. Speciation
2.4.1. Speciation in water and sediments
2.4.1.1 Detection and quantification
2.4.2. Speciation in biological matrices

3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

3.1. Natural sources
3.2. Anthropogenic sources
3.2.1. Production levels and processes
3.3. Copper use

4. ENVIRONMENTAL TRANSPORT AND DISTRIBUTION

4.1. Transport and distribution between media
4.1.1. Air
4.1.2. Water and sediment

4.1.3. Soil
4.1.4. Sewage sludge inputs to land
4.1.5. Biodegradation and abiotic degradation
4.2. Bioaccumulation
4.2.1. Microorganisms
4.2.2. Aquatic plants
4.2.3. Aquatic invertebrates
4.2.4. Fish
4.2.5. Terrestrial plants
4.2.6. Terrestrial invertebrates
4.2.7. Terrestrial mammals

5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

5.1. Environmental levels
5.1.1. Air
5.1.2. Water and sediment
5.1.3. Soil
5.1.4. Biota
5.1.4.1 Aquatic
5.1.4.2 Terrestrial
5.2. General population exposure
5.2.1. Air
5.2.2. Food and beverages
5.2.3. Drinking-water
5.2.3.1 Organoleptic characteristics
5.2.3.2 Copper concentrations in
drinking-water
5.2.4. Miscellaneous exposures
5.3. Occupational exposures
5.4. Total human intake of copper from all environmental
pathways

6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

6.1. Essentiality
6.2. Homoeostasis
6.2.1. Cellular basis of homoeostasis
6.2.2. Absorption in animals and humans
6.2.3. Transport, distribution and storage
6.2.4. Excretion
6.3. Methods of studying homoeostasis
6.3.1. Analytical methods
6.3.2. Intake
6.3.3. Diet
6.3.4. Balance studies
6.4. Biochemical basis of copper toxicity
6.5. Interactions with other dietary components
6.5.1. Protein and amino acids
6.5.2. Phytate and fibre
6.5.3. Ascorbic acid
6.5.4. Zinc
6.5.5. Iron
6.5.6. Carbohydrates

6.5.7. Infant diets
6.5.8. Other interactions (molybdenum, manganese,
selenium)

7. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS

7.1. Single exposure
7.1.1. Oral
7.1.2. Dermal
7.1.3. Inhalation
7.2. Short-term exposure
7.2.1. Oral
7.2.2. Inhalation
7.2.2.1 Copper(II) sulfate
7.2.2.2 Copper chloride
7.3. Repeated exposure: subchronic toxicity
7.3.1. Oral
7.3.1.1 Copper(II) sulfate
7.3.1.2 Copper chloride
7.4. Long-term exposure chronic toxicity or carcinogenicity
7.5. Reproductive and developmental toxicity
7.6. Mutagenicity and related end-points
7.6.1. Copper sulfate
7.6.1.1 In vitro
7.6.1.2 In vivo
7.6.2. Other copper compounds
7.6.2.1 In vitro
7.7. Other studies
7.7.1. Neurotoxicity
7.7.1.1 Copper sulfate
7.7.1.2 Copper chloride
7.7.2. Immunotoxicity
7.7.2.1 Copper(II) sulfate
7.8. Biochemical mechanisms of toxicity

8. EFFECTS ON HUMANS

8.1. General population: copper deficiency and toxicity
8.2. Copper deficiency
8.2.1. Clinical manifestations of copper deficiency
8.2.2. Biological indicators of copper deficiency:
balance studies
8.3. Toxicity of copper in humans
8.3.1. Single exposure
8.3.2. Repeated oral exposures
8.3.2.1 Gastrointestinal and hepatic effects
8.3.2.2 Reproduction and development
8.3.2.3 Cancer
8.3.3. Dermal exposure
8.4. Disorders of copper homoeostasis: populations at risk
8.4.1. Menkes disease
8.4.2. Wilson disease

8.4.3. Hereditary aceruloplasminaemia
8.4.4. Indian childhood cirrhosis
8.4.5. Idiopathic copper toxicosis, or non-Indian
childhood cirrhosis
8.4.6. Chronic liver diseases
8.4.7. Copper in infancy
8.4.8. Malabsorption syndromes
8.4.9. Parenteral nutrition
8.4.10. Haemodialysis patients
8.4.11. Cardiovascular diseases
8.5. Occupational exposure

9. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD

9.1. Bioavailability
9.1.1. Bioavailability in water
9.1.1.1 Predicting effects of copper on fish
gill function
9.1.2. Bioavailability of metals in sediments
9.2. Essentiality
9.2.1. Animals
9.2.2. Plants
9.2.2.1 Aquatic plants
9.2.2.2 Terrestrial plants
9.3. Toxic effects: laboratory experiments
9.3.1. Microorganisms
9.3.1.1 Water
9.3.1.2 Soil
9.3.2. Aquatic organisms
9.3.2.1 Plants
9.3.2.2 Invertebrates
9.3.2.3 Vertebrates
9.3.2.4 Model ecosystems and community
effects
9.3.3. Terrestrial organisms
9.3.3.1 Plants
9.3.3.2 Invertebrates
9.3.3.3 Vertebrates
9.4. Field observations
9.4.1. Microorganisms
9.4.2. Aquatic organisms
9.4.3. Terrestrial organisms
9.4.3.1 Tolerance
9.4.3.2 Copper fungicides and fertilizers

10. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE ENVIRONMENT

10.1. Concepts and principles to assess risk of adverse effects
of essential elements such as copper
10.1.1. Human health risks
10.1.2. Homoeostatic model

10.2. Evaluation of risks to human health
10.2.1. Exposure of general population
10.2.2. Occupational exposures
10.3. Essentiality versus toxicity in humans
10.3.1. Risk of copper deficiency
10.3.2. Risk from excess copper intake
10.3.2.1 General population
10.3.2.2 Occupational risks
10.4. Evaluation of effects on the environment
10.4.1. Concept of environmental risk assessment
10.4.2. Components of risk assessment process
for copper
10.5. Environmental risk assessment for copper
10.5.1. Aquatic biota
10.5.1.1 Overview of exposure data
10.5.1.2 Overview of toxicity data
10.5.2. Terrestrial biota
10.5.2.1 Overview of exposure data
10.5.2.2 Plant foliar levels
10.5.2.3 Assessment of toxicity of copper in
soil

11. CONCLUSIONS AND RECOMMENDATIONS FOR PROTECTION OF HUMAN HEALTH
AND THE ENVIRONMENT

11.1. Human health
11.2. Environmental protection

12. FURTHER RESEARCH

12.1. Health protection
12.2. Environmental protection

13. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES

REFERENCES

RESUME ET CONCLUSIONS

RESUMEN Y CONCLUCIONES

NOTE TO READERS OF THE CRITERIA MONOGRAPHS

Every effort has been made to present information in the criteria
monographs as accurately as possible without unduly delaying their
publication. In the interest of all users of the Environmental Health
Criteria monographs, readers are requested to communicate any errors
that may have occurred to the Director of the International Programme
on Chemical Safety, World Health Organization, Geneva, Switzerland, in
order that they may be included in corrigenda.

* * *

A detailed data profile and a legal file can be obtained from the
International Register of Potentially Toxic Chemicals, Case postale
356, 1219 Châtelaine, Geneva, Switzerland (telephone no. + 41
22 - 9799111, fax no. + 41 22 - 7973460, E-mail irptc@unep.ch).

* * *

This publication was made possible by grant number
5 U01 ES02617-15 from the National Institute of Environmental Health
Sciences, National Institutes of Health, USA, and by financial support
from the European Commission.

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WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR COPPER

Members

Professor D. Culver, retired from Department of Medicine, University
of Califomia, Califorma, USA

Professor H. Dieter, Institute for Water, Soil and Air Hygiene,
Federal Enviromnent Agency, Berlin, Germany

Dr R. Erickson, US Environniental Protection Agency, Duluth,
Minnesota, USA

Dr G.S. Fell, Department of Pathological Biochemistry, University
of Glasgow, Glasgow Royal Infirmary, Glasgow, Scotland

Dr J. Fitzgerald, Environmental Health Branch, Public and
Envircumental Health Service, South Australian Health Commission,
Rundle Mall, Adelaide, South Australia, Australia

Dr T.M. Florence, Centre for Environmental Health Sciences, Oyster
Bay, New South Wales, Australia

Professor J.L. Gollan, Brigham and Women's Hospital, Harvard Medical
School, Gastroenterology Division, Boston, Massachusetts, USA

Dr R.A. Goyer, University of Western Ontario, Chapel Hill, North
Carolina, USA ( Chairman)

Professor T.C. Hutchinson, Trent University, Environmental and
Resource Studies Program, Peterborough, Ontario, Canada

Ms M.E. Meek, Health Protection Branch, Environmental Health
Directorate, Health Canada, Ottawa, Ontario, Canada

Professor MR. Moore, National Research Centre for Environmental
Toxicology, The University of Queensland, Coopers Plains,
Queensland, Australia ( Co-Vice-Chairman)

Professer A. Oskarsson, Department of Food Hygiene, Faculty of
Veterinary Medicine, Swedish University of Agricultural Sciences,
Uppsala, Sweden

Dr S. Sethi, Department of Pathology, Lady Hardinge Medical College
and S.M.T. Sucheta Kripalani Hospital, New Delhi, India

Dr K.H. Summer, National Research Centre for Environment and
Health, Institute of Toxicology, Neuherberg, Germany

Dr J.H.M. Terninink, Department of Toxicology, Wageningen Agricultural
University, Wageningen, The Netherlands ( Co-Vice-Chairman)

Dr R. Uauy, University of Chile, Santiago, Chile

Dr J.M. Weeks, Institute of Terrestrial Ecology, Monks Wood,
Abbots Ripton, Huntingdon, Cambridgeshire, United Kingdom

Observers

Dr W.J. Adams, Kennecott Utah Copper, Magna, Utah, USA (Representing
ICA)

Dr K. Bentley, Department of Health and Family Services, Environmental
Health Policy, Canberra, Australia

Dr K.J. Buckett, Environmental Health Service, Health Department
of Western Australia, Perth, Western Australia, Australia

Professor J.C. Castilla, Ecology Department, Faculty of Biological
Sciences, Pontificia Universidad Catolica de Chile, Santiago, Chile
(Representing the Chilean Govemment)

Dr C. Fortin, Commercial Chemicals Evaluation Branch, Environment
Canada, Ottawa, Ontario, Canada

Dr R. Gaunt, RTZ Ltd, London, United Kingdom (Representing the
European Centre for Ecotoxicology and Toxicology of Chemicals)

Mr M. Thierry Gerschel, Trefîmetaux, Courbevoie, France (Eurometaux)

Dr P. Imray, Environmental Health Branch, Queensland Health,
Brisbane, Queensland, Australia

Mr C.M. Lee, International Copper Association, New York, USA

Dr E.V. Ohanian, Health and Ecological Criteria Division, Office of
Water, US Environinental Protection Agency, Washington, DC, USA

Dr J.-P. Robin, Noranda Metallurgy lue., Occupational Health & Safety,
McGill College, Montreal, Quebec, Canada (Representing ICME)

Secretariat

Dr G.C. Becking, International Programme on Chemical Safety
Inter-regional Research Unit, World Health Organization, Research
Triangle Park, North Carolina, USA ( Secretary)

Mr P. Callan, Departrnent of Health and Family Services, Environmental
Health Policy, Canberra, Australia) ( Co-rapporteur)

Dr C. Dameron, National Research Centre for Environmental Toxicology,
The University of Queensland, Coopers Plains, Queensland, Australia

Mr P.D. Howe, Institute of Terrestrial Ecology, Monks Wood, Abbots
Ripton, Huntingdon, Cambridgeshire, United Kingdom ( Co-rapporteur)

Dr L. Tomaska, Australian and New Zealand Food Authority, Canberra,
Australia ( Co-rapporteur)

WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR COPPER

A WHO Task Group on Enviromnental Health Criteria for Copper met
in Brisbane, Australia, from 24 to 28 June 1996. The meeting was
sponsored by a consortium of Australian Commonwealth and State
Govemments through a national steering committee chaired by Dr K.
Bentley, Director, Health and Envirorimentai Policy, Deparünent of
Health and Family Services, Canberra. ne meeting was co-hosted and
organized by the Department of Health and Family Services,
Commonwealth of Australia, the Queensland Depariments of Health,
Environment and Heritage, and the National Research Centre for
Environmental Toxicology. Participants were welcorned by Dr G.R.
Neville, Principal Medical Adviser, Queensland Health on behalf of the
host organizations. In opening the meeting, Dr G.C. Becking, on behalf
of Dr M. Mercier, Director of the IPCS and the three cooperating
organizations (UNEP/ILO/WHO), thanked the Australian Commonwealth and
State Govemments for their longstanding generous support in providing
funding for this Task Group as well as several previous IPCS Task
Groups and consultations over the last four years. lie thanked the
Staff of Queensland Health and the National Research Centre for
Environmental Toxicology for their excellent work in organizing the
Task Group for Copper. The Task Group reviewed and revised the draft
criteria monograph, and made an evaluation of the risks to human
heaith and the enviromnent from exposure to copper.

The first draft of this monograph was prepared by Dr C, Dameron
and colleagues at the National Research Centre for Environmental
Toxicology, Australia, and by Mr P.D. Howe, Institute of Terrestrial
Ecology, Monks Wood, United Kingdom. The Task Group draft,
incorperating the comments received fiom the IPCS Contact Points for
Enviromnental Health Criteria monographs, was prepared by Mr P.D. Howe
and the Secretariat.

Dr G.C. Becking (IPCS Central Unit, Interregional Research Unit)
and Ms K. Lyle (Sheffield, England) were responsible for the overall
scientific content and technical editing, respectively, of this
moriograph.

The efforts of all who helped in the preparation and
finalization of this publication are gratefully acknowledged.

ABBREVIATIONS

AAS atomic absorption spectroscopy

ALAD aminolaevulinic acid dehydratase

ALAT alanine aminotransferase

AROI acceptable range of oral intake

ASAT aspartate arninotransferase

ASV anodic stripping voltammetry

AVS acid volatile suffides

CEC cation exchange capacity

CNS central nervous system

CSV cathodic stripping voltarrimetry

CT^MAX critical thermal maxima

DT-OCEE deficiency toxicity optimum concentration for essential
elements

EDTA ethylene diamine tetraacetic acid

EPA Enviromnental Protection Agency (USA)

ER endoplasmic reticulum

FI-AAS flow-injection atornic absorption spectroscopy

GF-AAS graphite fumace atomic absorption spectroscopy

GLC gas liquid chromatography

GLC-MS gas liquid chromatography-mass spectrorrietry

HDL high density lipoprotein

HPLC high performance liquid chromatography

IC ion chrornatography

ICC Indian childhood cirrhosis

ICP-AES inductively coupled plasma-atornic emission spectroscopy

ICP-ES inductively coupled plasrna-emission Spectroscopy

ICP-MS inductively coupled plasma-mass spectrometry

ICT idiopathic copper toxicosis

LBW low birth weight

LDL low density lipoprotein

LEC Long-Evans Cinnamon (rat)

LOEC lowest-observed-effect concentration

MATC maximum acceptable toxicant concentration

MRE metal responsive element

NMR nuelcar magnetic resonance

NOAEL no-observed-adverse-effect level

NOEC no-observed-effect concentration

NOEL no-observed-effect level

NTA nitrilotriacetic acid

OCEE optimal concentration of essential elements

PIXE proton-induced X-ray fluorescence - PTDI
provisional tolerable daily intake

RER rough endoplasmic reticulum

SAAM standard algal assay medium

SER smooth endopiasmic reticulurn

SOD superoxide dismutase

TIMS thermal ionization mass spectrometry

UV ultraviolet

XRF X-ray fluorescence

1. SUMMARY AND CONCLUSIONS

1.1 Identity, physical and chemical properties

Copper is a reddish-brown, ductile and malleable metal. It
belongs to group IB of the Periodic Table. In compounds found in the
environment it usually has a valence of 2 but can exist in the
metallic, +1 and +3 valence states. Copper is found naturally in a
wide variety of mineral salts and organic compounds, and in the
metallic form. The metal is sparingly soluble in water, salt or
mildly acidic solutions, but can be dissolved in nitric and sulfuric
acids as well as basic solutions of ammonium hydroxide or carbonate.

Copper possesses high electrical and thermal conductivity and
resists corrosion.

1.2 Analytical methods

The wide range of copper species, inorganic and organic, has led
to the development of an array of sampling techniques, preparation and
analytical methods to quantify the element in environmental and
biological samples. Contamination of the samples with copper from
air, dusts, vessels or reagents during sampling and preparation is a
major source of analytical errors, and "clean" techniques are
essential.

Colorimetric and gravimetric methods for the measurement of
copper are simple to use and are inexpensive; however, their
usefulness is limited to situations where extreme sensitivity is not
essential. For measurement of low concentrations of copper in various
matrices, atomic absorption spectrophotometric (AAS) methods are the
most widely used. A dramatic increase in sensitivity is obtained by
the utilization of graphite furnace atomic absorption
spectrophotometry (GF-AAS) rather than flame AAS. Depending upon
sample pretreatment, separation and concentration procedures,
detection limits of about 1 µg/litre in water by GF-AAS and 20
µg/litre by AAS have been reported and levels of 0.05-0.2 µg/g of
tissue have been detected by GF-AAS. Greater sensitivities can be
achieved through the use of emission techniques such as high
temperature inductively coupled argon plasma techniques followed by
atomic emission spectroscopy (ICP-AES) or a mass spectrometer
(ICP-MS). Other more sensitive and specialized methodologies are
available such as X-ray fluorescence, ion-selective electrodes and
potentiometric methods, and anodic stripping and cathodic stripping
voltametry.

1.3 Sources of human and environmental exposure

Natural sources of copper exposure include windblown dust,
volcanoes, decaying vegetation, forest fires and sea spray.
Anthropogenic emissions include smelters, iron foundries, power
stations and combustion sources such as municipal incinerators. The
major release of copper to land is from tailings and overburdens from

copper mines and sewage sludge. Agricultural use of copper products
accounts for 2% of copper released to soil.

Copper ores are mined, smelted and refined to produce many
industrial and commercial products. Copper is widely used in cooking
utensils and water distribution systems, as well as fertilizers,
bactericides, fungicides, algicides and antifouling paints. It is
also used in animal feed additives and growth promoters, as well as
for disease control in livestock and poultry. Copper is used in
industry as an activator in froth flotation of sulfide ores,
production of wood preservatives, electroplating, azo-dye manufacture,
as a mordant for textile dyes, in petroleum refining and the
manufacture of copper compounds.

1.4 Environmental transport, distribution and transformation

Copper is released to the atmosphere in association with
particulate matter. It is removed by gravitational settling, dry
deposition, washout by rain and rainout. Removal rate and distance
travelled from the source depend on source characteristics, particle
size and wind velocity.

Copper is released to water as a result of natural weathering of
soil and discharges from industries and sewage treatment plants.
Copper compounds may also be intentionally applied to water to kill
algae. Several processes influence the fate of copper in the aqueous
environment. These include complex formation, sorption to hydrous
metal oxides, clays and organic materials, and bioaccumulation.
Information on the physicochemical forms of copper (speciation) is
more informative than total copper concentrations. Much of the copper
discharged to water is in particulate form and tends to settle out,
precipitate out or be adsorbed by organic matter, hydrous iron,
manganese oxides and clay in the sediment or water column. In the
aquatic environment the concentration of copper and its
bioavailability depend on factors such as water hardness and
alkalinity, ionic strength, pH and redox potential, complexing
ligands, suspended particulate matter and carbon, and the interaction
between sediments and water.

The largest release of copper is to land; the major sources of
release are mining operations, agriculture, solid waste and sludge
from treatment works. Most copper deposited in soil is strongly
adsorbed and remains in the upper few centimetres of soil. Copper
adsorbs to organic matter, carbonate minerals, clay minerals, hydrous
iron and manganese oxides. The greatest amount of leaching occurs from
sandy acidic soils. In the terrestrial environment a number of
important factors influence the fate of copper in soil. These include
the nature of the soil itself, pH, presence of oxides, redox
potential, charged surfaces, organic matter and cation exchange.

Bioaccumulation of copper from the environment occurs if the
copper is biologically available. Accumulation factors vary greatly
between different organisms, but tend to be higher at lower exposure
concentrations. Accumulation may lead to exceptionally high body
burdens in certain animals (such as bivalves) and terrestrial plants
(such as those growing on contaminated soils). However, many
organisms are capable of regulating their body copper concentration.

1.5 Environmental levels and human exposure

The concentration of copper in air depends on the proximity of
the site to major sources such as smelters, power plants and
incinerators. Copper is widely distributed in water because it is a
naturally occurring element. However, care must be taken when
interpreting copper concentrations in the aquatic environment. In
aquatic systems the environmental levels of copper are usually
measured as either total or dissolved concentrations, with the latter
being more representative of the bioavailability of the metal.

Average background concentrations of copper in air in rural areas
range from 5 to 50 ng/m³. Copper levels in seawater of 0.15 µg/litre
and in fresh water of 1-20 µg/litre are found in uncontaminated areas.
Sediment is an important sink and reservoir for copper. Background
levels of copper in natural freshwater sediments range from 16 to 5000
mg/kg (dry weight). Copper levels in marine sediments range from 2 to
740 mg/kg (dry weight). In anoxic sediments copper is bound strongly
by sulfide and therefore not bioavailable. Median copper
concentrations in uncontaminated soil were reported to be 30 mg/kg
(range 2-250 mg/kg). Copper is accumulated by plants, invertebrates
and fish. Higher concentrations of copper have been reported in
organisms from copper-contaminated sites than in those from
non-contaminated sites.

For healthy, non-occupationally-exposed humans the major route of
exposure to copper is oral. The mean daily dietary intake of copper
in adults ranges between 0.9 and 2.2 mg. A majority of studies have
found intakes to be at the lower end of that range. The variation
reflects different dietary habits as well as different agricultural
and food processing practices used worldwide. In some cases,
drinking-water may make a substantial additional contribution to the
total daily intake of copper, particularly in households where
corrosive waters have stood in copper pipes. In homes without copper
piping or with noncorrosive water, copper intake from drinking-water
seldom exceeds 0.1 mg/day, although intakes greater than a few mg per
day can result from corrosive water distributed through copper pipes.
In general, total daily oral intakes of copper (food plus
drinking-water) are between 1 and 2 mg/day, although they may
occasionally exceed 5 mg/day. All other intakes of copper (inhalation
and dermal) are insignificant in comparison to the oral route.
Inhalation adds 0.3-2.0 µm/day from dusts and smoke. Women using
copper IUDs are exposed to only 80 µg or less of copper per day from
this source.

1.6 Kinetics and metabolism in laboratory animals and humans

The homoeostasis of copper involves the dual essentiality and
toxicity of the element. Its essentiality arises from its specific
incorporation into a large number of proteins for catalytic and
structural purposes. The cellular pathways of uptake, incorporation
into protein and export of copper are conserved in mammals and
modulated by the metal itself.

Copper is mainly absorbed through the gastrointestinal tract.
From 20 to 60% of the dietary copper is absorbed, with the rest being
excreted through the faeces. Once the metal passes through the
basolateral membrane it is transported to the liver bound to serum
albumin. The liver is the critical organ for copper homoeostasis.
The copper is partitioned for excretion through the bile or
incorporation into intra- and extracellular proteins. The primary
route of excretion is through the bile. The transport of copper to
the peripheral tissues is accomplished through the plasma attached to
serum albumin, ceruloplasmin or low-molecular-weight complexes.

The methods used to study copper homoeostasis in mammals include
dietary analyses and balance studies. Isotope and standardized
biochemical analyses of these processes are essential to understand
copper deficiency and excess.

The biochemical toxicity of copper, when it exceeds homoeostatic
control, is derived from its effects on the structure and function of
biomolecules such as DNA, membranes and proteins directly or through
oxygen-radical mechanisms.

1.7 Effects on laboratory animals and in vitro test systems

The toxicity of a single oral dose of copper varies widely
between species (LD₅₀ range 15-1664 mg Cu/kg body weight). The more
soluble salts (copper(II) sulfate, copper(II) chloride) are generally
more toxic than the less soluble salts (copper(II) hydroxide,
copper(II) oxide). Death is preceded by gastric haemorrhage,
tachycardia, hypotension, haemolytic crisis, convulsions and
paralysis. LD₅₀ values for dermal exposure were reported at > 1124
and > 2058 mg Cu/kg body weight in rats and rabbits respectively.
The inhalation LC₅₀ (exposure duration unspecified) was > 1303 mg
Cu/kg body weight in rabbits, and respiratory function was impaired in
guinea-pigs exposed to 1.3 mg Cu/m³ for 1 h.

Rats given up to 305 mg Cu/kg per day orally in the diet as
copper(II) sulfate for 15 days showed alterations in blood
biochemistry and haematology (particularly anaemia) and adverse
effects on the liver, kidney and lungs. Effects were qualitatively
similar with other copper compounds and in other species. The
no-observed-effect level (NOEL) in this study was 23 mg Cu/kg body
weight per day. However, sheep were particularly sensitive and
repeated doses of 1.5-7.5 mg Cu/kg body weight per day as copper(II)
sulfate or copper(II) acetate resulted in progressive liver damage,
haemolytic crisis and ultimately death.

Long-term exposure in rats and mice showed no overt signs of
toxicity other than a dose-related reduction in growth after ingestion
of 138 mg Cu/kg body weight per day (rats) and 1000 mg Cu/kg body
weight per day (mice). The no-observed-adverse-effect level (NOAEL)
was 17 mg Cu/kg body weight per day in rats, and 44 and 126 mg Cu/kg
body weight per day in male and female mice, respectively. The effects
included inflammation of the liver and degeneration of kidney tubule
epithelium.

Studies of reproductive and developmental toxicity were limited.
Some testicular degeneration and reduced neonatal body and organ
weights were seen in rats at dose levels in excess of 30 mg Cu/kg body
weight per day over extended time periods, and fetotoxic effects and
malformations were seen at high dose levels (> 80 mg Cu/kg body
weight per day).

Copper(II) sulfate was not mutagenic in bacterial assays.
However, a dose-related increase in unscheduled DNA synthesis was seen
in rat hepatocytes. In the mouse micronucleus assay, one study showed
a significant increase in chromosome breaks at the highest intravenous
dose (1.7 mg Cu/kg body weight) but no effect was seen in another
study at intravenous doses up to 5.1 mg Cu/kg body weight.

Studies of neurotoxicity have not shown effects on behaviour but
neurochemical changes have been reported after oral administration of
20-40 mg Cu/kg body weight per day. A limited number of
immunotoxicity studies showed humoral and cell-mediated immune
function impairment in mice after oral intakes from drinking-water of
about 10 mg Cu/kg body weight per day.

1.8 Effects on humans

Copper is an essential element and adverse health effects are
related to deficiency as well as excess. Copper deficiency is
associated with anaemia, neutropenia and bone abnormalities but
clinically evident deficiency is relatively infrequent in humans.
Balance data may be used to anticipate clinical effects, whereas serum
copper and ceruloplasmin levels are useful measures of moderate to
severe deficiency but less sensitive measures of marginal deficiency.

Except for occasional acute incidents of copper poisoning, few
effects are noted in normal populations. Effects of single exposure
following suicidal or accidental oral exposure have been reported as
metallic taste, epigastric pain, headache, nausea, dizziness, vomiting
and diarrhoea, tachycardia, respiratory difficulty, haemolytic
anaemia, haematuria, massive gastrointestinal bleeding, liver and
kidney failure, and death. Gastrointestinal effects have also
resulted from single and repeated ingestion of drinking-water
containing high copper concentrations, and liver failure has been
reported following chronic ingestion of copper. Dermal exposure has
not been associated with systemic toxicity but copper may induce
allergic responses in sensitive individuals. Metal fume fever from
inhalation of high concentrations in the air in the occupational

setting has been reported and, although other respiratory effects have
been attributed to exposure to mixtures containing copper (e.g.
Bordeaux mix, mining and smelting), the role of copper has not been
demonstrated. Workers apparently exposed to high air levels resulting
in an estimated intake of 200 mg Cu/day developed signs suggesting
copper toxicity (e.g. elevated serum copper levels, hepatomegaly).
Available data on reproductive toxicity and carcinogenicity are
inadequate for risk assessment.

A number of groups are described where apparent disorders in
copper homoeostasis result in greater sensitivity to copper deficit or
excess than the general population. Some disorders have a
well-defined genetic basis. These include Menkes disease, a generally
fatal manifestation of copper deficiency; Wilson disease
(hepatolenticular degeneration), a condition leading to progressive
accumulation of copper; and hereditary aceruloplasminaemia, with
clinical symptoms of iron overload. Indian childhood cirrhosis (ICC)
and idiopathic copper toxicosis (ICT) are conditions related to excess
copper which may be associated with genetically based copper
sensitivity, although this has not been demonstrated unequivocally.
These are fatal liver conditions in early childhood where copper
accumulates in the liver. Incidences of the diseases were related to
high copper intake, at least in some cases.

Other groups potentially sensitive to copper excess are
haemodialysis patients and subjects with chronic liver disease.
Groups at risk of copper deficiency include infants (particularly low
birth weight/preterm babies, children recovering from malnutrition,
and babies fed exclusively with cow's milk), people with malabsorption
syndromes (e.g. coeliac disease, sprue, cystic fibrosis), and patients
on total parenteral nutrition. Copper deficiency has been implicated
in the pathogenesis of cardiovascular disease.

1.9 Effects on other organisms in the laboratory and field

The adverse effects of copper must be balanced against its
essentiality. Copper is an essential element for all biota, and care
must be taken to ensure the copper nutritional needs of organisms are
met. At least 12 major proteins require copper as an integral part of
their structure. It is essential for the utilization of iron in the
formation of haemoglobin, and most crustaceans and molluscs possess
the copper-containing haemocyanin as their main oxygen-carrying blood
protein. In plants copper is a component of several enzymes involved
in carbohydrate, nitrogen and cell wall metabolism.

A critical factor in assessing the hazard of copper is its
bioavailability. Adsorption of copper to particles and complexation
by organic matter can greatly limit the degree to which copper will be
accumulated and elicit effects. Other cations and pH can also
significantly affect bioavailability.

Copper has been shown to exert adverse reproductive, biochemical,
physiological and behavioural effects on a variety of aquatic
organisms. Copper concentrations as low as 1-2 µg/litre have been
shown to have adverse effects on aquatic organisms; however, large
variations due to species sensitivity and bioavailability must be
considered in the interpretation and application of this information.

In natural phytoplankton communities chlorophyll a and nitrogen
fixation were significantly reduced at copper concentrations of
> 20 µg/litre and carbon fixation was significantly reduced at
> 10 µg/litre. EC₅₀s (72 h) for algae, based on growth
inhibition, range from 47 to 120 µg Cu/litre.

For freshwater invertebrates, 48-h L(E)C₅₀s range from 5 µg
Cu/litre for a daphnid species to 5300 µg Cu/litre for an ostracod.
For marine invertebrates 96-h LC₅₀s range from 29 µg Cu/litre for the
bay scallop to 9400 µg Cu/litre for the fiddler crab. The acute
toxicity of copper to freshwater and marine fish is highly variable.
For freshwater fish 96-h LC₅₀s range from 3 µg Cu/litre (Arctic
grayling) to 7340 µg Cu/litre (bluegill). For marine fish 96-h LC₅₀s
range from 60 µg Cu/litre for chinook salmon to 1400 µg Cu/litre for
grey mullet.

Although plants require copper as a trace element, at high soil
levels copper can be extremely toxic. Generally visible symptoms of
metal toxicity are small chlorotic leaves and early leaf fall. Growth
is stunted and initiation of roots and development of root laterals
are poor. Reduced root development may result in a lowered water and
nutrient uptake which leads to disturbances in the metabolism and
growth retardation. At the cellular level, copper inhibits a large
number of enzymes and interferes with several aspects of plant
biochemistry (including photosynthesis, pigment synthesis and membrane
integrity) and physiology (including interference with fatty acids,
protein metabolism and inhibition of respiration and nitrogen fixation
processes).

Toxic effects have been observed in laboratory studies of
earthworms exposed to copper in soil; cocoon production is the most
sensitive parameter measured, with significant adverse effects at
50-60 mg Cu/kg.

Adverse field effects on soil microorganisms have been correlated
with enhanced copper concentrations in areas where copper-containing
fertilizers have been applied and in areas near to copper-zinc
smelters. In citrus-growing areas, to which copper-containing
fungicides have been applied, leaf chlorosis has been found to be
significantly correlated with soil copper levels.

Tolerance to copper has been demonstrated in the environment for
phytoplankton, aquatic and terrestrial invertebrates, fish and
terrestrial plants. Tolerance mechanisms which have been proposed in
plants include binding of metal to cell wall material, presence of

metal-tolerant enzymes, complex formation with organic acids with
subsequent removal to the vacuole, and binding to specialized
thiol-rich proteins or phytochelatins.

1.10 Conclusions

1.10.1 Human health

The lower limit of the acceptable range of oral intake (AROI) is
20 µg Cu/kg body weight per day. This figure is arrived at from the
adult basal requirement with an allowance for variations in copper
absorption, retention and storage (WHO, 1996). In infancy, this
figure is 50 µg Cu/kg body weight per day.

The upper limit of the AROI in adults is uncertain but it is most
likely in the range of several but not many mg per day in adults
(several meaning more than 2-3 mg/day). This evaluation is based
solely on studies of gastrointestinal effects of copper-contaminated
drinking-water. A more specific value for the upper AROI could not be
confirmed for any segment of the general population. We have limited
information on the level of ingestion of copper from food that would
provoke adverse health effects.

The available data on toxicity in animals were considered
unhelpful in establishing the upper limit of the AROI, owing to
uncertainty about an appropriate model for humans. Moreover,
traditional methodology for safety assessment, based on application of
uncertainty factors to data in animals, does not adequately address
the special attributes of essential elements such as copper.

From available data on human exposures worldwide, but
particularly in Europe and the Americas, there is greater risk of
health effects from deficiency of copper intake than from excess
copper intake.

1.10.2 Environmental effects

Protection of aquatic life in waters with high bioavailability
will require limiting total dissolved copper to some concentration
less than 10 µg/litre; however, the appropriate concentration limit
will depend on the biota and exposure conditions at sites of concern
and should be set based on further evaluation of all relevant data.

At many sites, physicochemical factors limiting bioavailability
will warrant higher copper limits. Regulatory criteria should take
into account the speciation of copper if dischargers can demonstrate
that the bioavailability of copper in the receiving water can be
measured reliably.

When sampling and analysing environmental media for copper, it is
essential that "clean" techniques be employed.

Because copper is an essential element, procedures to prevent
toxic levels of copper should not incorporate safety factors that
result in recommended concentrations being below natural levels.

2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES AND ANALYTICAL METHODS

2.1 Identity

Copper, the 29th element and the first in group IB of the
Periodic Table, displays four oxidation states: metallic copper Cu⁰,
cuprous ion Cu⁺, cupric Cu²⁺ and trivalent copper ion Cu³⁺.
Copper also forms organometallic compounds. The natural isotopic
abundance is 69.17% ⁶³Cu and 30.83% ⁶⁵Cu, giving the element an
average relative atomic mass of 63.546 (Lide & Frederikse, 1993b).
The limited range of stable isotopes and their common distribution has
inhibited isotopic distribution studies. Useful radioactive copper
isotopes are ⁶⁴Cu (12.701 h half-life) and ⁶⁷Cu (61.92 h half-life);
they decay with the production of ß-particles and gamma-rays (Lide &
Frederikse, 1993b) and are produced in synchrotrons for physical and
biological studies.

Copper is found in a wide variety of mineral salts and organic
compounds, and can also be found naturally in the elemental or
metallic form. The metal is a dull lustrous reddish-brown in colour,
malleable, a good thermal conductor and an excellent electrical
conductor. The metallic form is very stable to dry air at low
temperatures but undergoes a slow reaction in moist air to produce a
hydroxycarbonate or hydroxysulfate that forms a greenish-grey
amorphous film over the surface which protects the underlying metal
from further attack. The metal is sparingly soluble in water, in salt
solutions and in mildly acidic solutions, but can be dissolved in
nitric acid and sulfuric acid as well as in basic solutions of
ammonium hydroxide, ammonium carbonate and cyanide in the presence of
oxygen (Cotton & Wilkinson, 1989).

The electronic configuration of the metallic (Cu⁰) form is
1s²2s²2p⁶3s²3p⁶3d¹⁰4p¹. The common solution oxidation states
are the cuprous (Cu(I) 3d¹⁰) or the cupric (Cu(II) 3d⁹) forms. The
chemistry of the element, especially in biological systems, is
profoundly affected by the electronic/oxidation state. The facile
exchange between oxidation states endows the element with redox
properties which may be of an essential or deleterious nature in
biological systems.

The most important oxidation state in natural, aqueous
environments is copper(II). Any copper(I) present is quickly oxidized
by any oxidizing reagent present, or in a disproportionation reaction,
unless it is stabilized by complex formation. The copper(II) ion
binds preferentially via oxygen to inorganic ligands such as H₂O, OH^-,
CO₃^2-, SO₄^2-, etc. and to organic ligands via phenolic and
carboxylic groups (Cotton & Wilkinson, 1989). Thus, almost all of the
copper in natural samples is complexed with organic compounds
(Neubecker & Allen, 1983; Nor, 1987; Allen & Hansen, 1996).

Many cupric compounds and complexes are soluble in water and have
a characteristic aqua-blue-green colour. The trivalent form of copper
is found in only a few compounds and is a strong oxidizing agent
(Cotton & Wilkinson, 1989). In environmental and mineral environments

the divalent oxidation state readily adsorbs to a variety of hydrated
metal oxides including those of iron, aluminium and manganese (Grant
et al., 1990).

Identification, quantification and speciation of copper is
described in sections 2.3 and 2.4 and the influences on the speciation
in water and soil are described in section 2.4.1.

2.2 Physical and chemical properties

The physical and chemical properties of copper and some of its
salts are summarized in Table 1.

2.3 Analytical methods

The wide range of copper species, inorganic and organic, has lead
to the development of an array of sampling techniques and preparative
and analytical methods to quantify the element in environmental and
biological samples. The following sections offer a brief overview of
these methodologies.

2.3.1 Sampling and sample preparation

Sampling and the subsequent work-up is highly dependent on the
type of sample being analysed and the level of detail needed to
evaluate it. Most of the techniques described below suffer at some
level from the effects of the surrounding milieu or matrix.
Qualitative analysis to determine the presence of copper in a sample,
for instance, may or may not require consideration of the matrix,
whereas quantitation of metals usually does. Quantitation of the
various forms of copper requires a detailed evaluation of the matrix
and the techniques being used.

2.3.1.1 Sampling

Owing to the abundance of copper in the environment, the
collection of samples for copper analysis requires precautions to
avoid accidental contamination. Most plastics and glassware are
relatively free of copper contamination but care should be taken to
avoid heavily pigmented plastics that could contain copper or other
metals that might compromise the analysis. Interference by
contaminating metals is more likely to be a problem in colorimetric
analyses. Vessels to be used in the collection of samples for copper
analysis should be cleaned of dust and debris and washed with a dilute
metal-free mineral acid such as 0.1 mol/litre hydrochloric or nitric
acid, rinsed copiously with clean distilled water and dried in a
dust-free area. Copper is frequently and naturally found in
industrial and household dusts (Kim & Fergusson, 1993) so care should
be taken that the samples are not contaminated. Removal of copper
from washing and rinsing water, and even distilled water, can be
compromised by the use of copper plumbing and brass fixtures. Removal
of metals and other ions can be accomplished through the use of
ion-exchange resins.

Table 1. Physical and chemical properties of copper and some of its salts^a

Copper Copper(II) Cuprous(I) Copper(II) Copper(II) Oxine-copper^b
sulfate oxide hydroxide chloride

CAS registry number 7440-50-8 7758-98-7 1317-39-1 20427-59-2 7447-39-4 10280-28-6

Molecular formula Cu CuSO₄ Cu₂O Cu(OH)₂ CuCl2 C₁₈H₁₂CuN₂O₂

Relative molecular mass 63.55 159.6 141.3 97.56 134.45 351.9

Boiling point (°C) 2567 decomposes to decomposes at decomposes at
CuO at 650 °C 140 °C 993 °C

Melting point (°C) 1083.4 slightly decomposes 1235 decomposes 620 decomposes
at > 200°C at 270°C

Vapour pressure (kPa) 1.33 at
1870 °C

Water solubility insoluble 143 g/litre practically 2.9 mg/litre 706 g/litre insoluble
at 0°C insoluble at 25 °C

^a Lide & Frederikse (1993)
^b Copper 8-hydroxyquinolinate.

2.3.1.2 Separation and concentration

It is not generally necessary that the metal itself be isolated
before analysis, but frequently the metal or at least the inorganic
portion of the sample must be concentrated. The requirement for
concentration of the sample depends on the sensitivity of analytical
method to be employed.

Particulates (dust, smoke, spray) are sampled from air on filters
before analysis. Aqueous samples may need to be dried or concentrated
using an ion-exchange procedure (Vermeiren et al., 1990; Chakrabarti
et al., 1994).

Total copper (in water) includes all forms of copper
irrespective of form, whether dissolved or bound. Suspended copper
refers to copper attached to suspended particles in water large enough
to be filtered by a 0.45 µm membrane filter. Dissolved copper is
defined operationally as all forms of copper which pass through a 0.45
µm membrane filter (ATSDR, 1990). Separation of dissolved and
suspended forms of copper requires filtering. Special measures must
be taken to avoid sample contamination when filtering. First, the
membrane filter and filter holder must be acid cleaned. The filter
must be discarded and the filter holder should be acid rinsed between
samples and subsequently rinsed with metal-free water. Second, glass
fibre filters must not be used. Third, the filter holder and membrane
filter must be conditioned with the sample, i.e. an initial portion of
the sample filtered and discarded. Lastly, if positive pressure
filtration is used, the gas must be passed through a 0.2 µm in-line
filter.

2.3.1.3 Sample preparation

Direct analysis of metals with little modification or preparation
of the sample is desirable but frequently not achievable. Direct
analysis of copper is appropriate when relatively concentrated samples
are analysed (0.1-2 mg/litre or higher), provided they are very low in
interfering inorganics and especially organic materials. More dilute
samples can be concentrated as described above. Concentrated samples
can be diluted with appropriate diluents, usually distilled water or
dilute copper-free mineral acid solutions. Care should be taken to
keep the pH near or below neutral to avoid the formation of insoluble
copper hydroxides.

Sample preparation for the most widely utilized analytical
techniques, or where the removal of the organic matrix is required, is
generally achievable by means of a preceding open vessel oxidative
degradation step involving nitric acid or acid mixtures such as aqua
regia or sulfuric acid/hydrogen peroxide. (Perchloric acid is less
frequently used because of its explosive nature.) A procedure using a
mixture of nitric, perchloric and hydrofluoric acids was reported to
give good recoveries of metals including cadmium, chromium, copper,
manganese, nickel, lead and zinc in estuarine sediments (Bello et al.,
1994). Recently, oxidative UV photolysis (Kolb et al., 1992) and

microwave-assisted acid digestion in a closed vessel have become more
popular in sample preparation for various sample matrices prior to
elemental analyses. Microwave-assisted digestion has been employed as
a sample preparation procedure prior to the measurement of copper
level in human bone (Baranowska et al., 1995), in duck eggs (Jeng &
Yang, 1995), in sediments by anodic stripping voltametry (Olsen et
al., 1994), in marine biological tissues such as mollusc, fish and
crustacean by AAS (Baldwin et al., 1994), in steels and copper alloys
by ICP-AES (Borszeki et al., 1994), and in plant materials (Matejovic
& Durackova, 1994). The microwave digestion procedure is fast
becoming the method of choice because sample preparation is rapid and
the values of blanks are significantly lower than in the traditional
wet and dry mineralization methods (Matejovic & Durackova, 1994). A
fast and quantitative on-line microwave digestion/extraction of copper
from different solid matrices, such as vegetables, powdery dietary
products and sewage sludge, was developed using a flow
injection-atomic absorption system (FI-AAS) (Delaguardia et al.,
1993). A similar FI-AAS method for the determination of copper in
whole blood was also reported by Burguera et al. (1993).

2.3.1.4 "Clean" techniques for measurement of ultratrace copper levels

Information provided by Shiller & Boyle (1987), Windom et al.
(1991) and Hurley et al. (1996) has raised questions concerning the
quality of data collected and reported for trace metals analysis over
the past several decades. The concern is that insufficient care in
sampling, sample preparation and analysis have resulted in samples
being contaminated and the values reported in the sub-mg/litre range
have questionable accuracy. It has been shown that many published
literature values for surface waters are biased on the high side owing
to contamination and/or matrix interferences. Matrix interferences
commonly encountered in copper analyses are chemical, spectral,
ionization and high dissolved solids. Copper determination by ICP
emission spectroscopy (ICP-ES) can suffer from interference by iron,
thallium and vanadium (US EPA, 1986). Copper determination by ICP-MS
emission spectroscopy is susceptible to interference from chlorides,
although procedures have been developed to overcome this interference
in blood serum samples, for example (Lyon & Fell, 1990). Both ICP-ES
and ICP-MS are excellent techniques for measuring copper if care is
taken to eliminate interferences. "Clean" techniques (Prothro, 1993;
US EPA, 1995) address the problem associated with making accurate and
precise trace determinations of metals particularly when attempting to
lower detection limits and report microgram/litre and
sub-microgram/litre concentrations. "Clean" techniques require
special attention to be paid in seven areas:

1. use of "clean" techniques during collecting, handling, storing,
preparing and analysing samples to avoid contamination
2. use of analytical methods that have sufficiently low detection
limits
3. avoidance of interference in the quantification step
4. use of blanks to assess contamination
5. use of matrix spikes and certified reference materials (CRMs) to
assess interference and contamination

6. use of replicates to assess precision
7. use of certified standards.

To achieve accurate and precise measurement of any particular
sample, it is recommended that both the detection limit and the blank
value should be less than one-tenth the sample concentration. This is
a stringent requirement, but one that is especially important in
measuring metals at concentrations near the method detection limit and
at environmentally relevant concentrations. The methods employed to
attain these goals seek to increase sensitivity, decrease
contamination and decrease interference. The specific recommendations
used to achieve these goals and address the seven items above are
provided in Prothro (1993).

2.3.2 Detection and measurement

2.3.2.1 Gravimetric and colorimetric methods

Gravimetric and colorimetric methods were the earliest procedures
used for the measurement of copper. Gravimetric methods are
non-specific and may precipitate other cations including zinc,
cadmium, cobalt and nickel. Useful spectrophotometric reagents for
copper include cuprizone (biscyclohexanoneoxalydihydrazone) (Peterson
& Bollier, 1955), bathrocuproinedisulfonic acid
(2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid) (Zak,
1958), bathocuproine (dimethyl-4,7-diphenyl-1,10-phenanthroline)
(Wharton & Rader, 1970) and more recently 1-(2-pyridylazo)-2-naphthol
(Malvankar & Shinde, 1991), BPKQH (benzyl 2-pyridyl ketone
2-quinolylhydrazone (Garcia-Sanchez et al., 1990) and
2,2'-bichinchioninic acid (Brenner & Harris, 1995). The bathocuproine
method can achieve a limit of detection of 2 µg Cu/litre in water
samples.

Although colorimetric methods can suffer from lack of
specificity, they are nevertheless useful, especially in laboratories
where more sophisticated instrumentation is not available. Beyond a
spectrophotometer and an analytical balance, no specialized equipment
is required. In addition, the methods are, in general, simple,
inexpensive, easily taught and rapidly carried out. Because of these
advantages they should be considered in situations where extreme
sensitivity is not essential.

2.3.2.2 Atomic absorption, emission and mass spectrometry methods

Atomic absorption spectrophotometric (AAS) methods are the most
widely used for the determination of copper in various matrices. A
dramatic increase in sensitivity over that obtained by flame AAS is
obtained with GF-AAS. Increasingly more common is the use of emission
methods in which the sample is introduced into a high temperature
inductively coupled argon plasma (ICP) where the element is rapidly
vaporized and ionized. The element is detected and quantified by
atomic emission spectroscopy (ICP-AES).

A further increase in sensitivity is obtained through the
coupling of the ICP to a mass spectrometer (ICP-MS). The attraction
of the ICP methods is the ability to do multielemental analysis
(Vollkopf & Barnes, 1995) which is the obvious advantage over other
spectroscopic techniques. The ICP-MS technique has the additional
advantage that isotopic information can be obtained, which is
especially useful if stable isotopes of copper are used for
bioavailability and other studies (Lyon et al., 1988, 1995, 1996). An
isotope dilution ICP-MS method (Beary et al., 1994) reported precision
of less than 0.15% for copper and cadmium in zinc ore and for copper
and molybdenum in domestic sludge; others (Lu et al., 1993) reported a
more conservative precision of less than 1% and a detection limit of
58 ng/litre for copper in a number of biological and environmental
reference materials. The International Standards Organization have
published procedures using AAS for the analysis of copper in water
between 0.05 and 200 µg/litre (ISO, 1986). Detection limits are
summarized in Table 2.

2.3.2.3 Specialized methodologies

Many X-ray fluorescence (XRF) methods, which are nondestructive
techniques, have been published for the determination of trace
elements including copper. XRF has for a long time been used as a
rapid and convenient method for trace element determination although
its sensitivity is somewhat lower than anodic stripping voltametry
(ASV) (Viksna et al., 1995). The technique can be used for a variety
of sample types, such as human serum (Viksna et al., 1995),
electrolyte purification solutions (Davidson et al., 1994), human
kidney tumours (Hamilton et al., 1972) and contaminated soils (Wilson
et al., 1995). Field instruments are available for scans of
contaminated sites to estimate the metal in the surface layer of the
soil. A proton-induced X-ray fluorescence technique (PIXE) was also
reported for the measurement of trace elements in amniotic fluid
(Napolitano et al., 1994).

Ion-selective electrode and potentiometric methods have been used
for copper speciation in soil (Town & Powell, 1993), and in seawater
(Román & Rivera, 1992; Soares et al., 1994). Voltammetric methods
have comparable sensitivity to conventional AAS, but also offer
speciation capability (Scarano et al., 1990; Chakrabarti et al., 1994;
Cheng et al., 1994). Voltammetric/potentiometric analyses offer
sensitivity in the parts per billion (µg/kg) range for copper and some
other metals. Potentiometric analysis relies on the elements
electrochemical properties. An attraction of potentiometric methods
is their ability to help in the speciation of copper and limited
multielement detection. ASV has been used to analyse copper in foods
(Holak, 1983). Cathodic stripping voltametry (CSV) is an extremely
sensitive method for copper in both seawater and fresh water, with a
limit of detection of 0.005 µg/litre (Donat et al., 1994).

Some analytical methods for the detection of copper in different
media are summarized in Table 2.

Table 2. Analytical methods for the detection of copper

Medium Sample Method^a Detection Reference
preparation limit

Air filter collection on ICP-AES 1 µg ATSDR
0.8 µm membrane; (1990)
acid digestion

filter collection on AAS 0.05 µg ATSDR
0.8 µm membrane; (1990)
acid digestion

Fresh acidify with 1:1 AAS 20 µg/litre US EPA
water HNO₃ to a pH < 2 (1986)

sample solutions GF-AAS 1 µg/litre US EPA
should contain 0.5% (1986)
HNO₃

filter and acidity ICP 2-10 µg/litre US EPA
sample (1986)

filter and acidity ICP-AES 6 µg/litre ATSDR
sample (1990)

acid digestion with ICP-MS 0.01 µg/litre US EPA
HNO₃, reflux and (1994)
dilute with type 1
water

Sediment acid digestion AAS 1.0 µg/g US EPA
acid digestion GF-AAS 0.05-0.20 µg/g (1986)
acid digestion ICP 0.20-0.50 µg/g US EPA
acid digestion ICP-MS 0.025-0.005 µg/g (1986)

Tissue acid digestion AAS 0.5-1.0 µg/g US EPA
acid digestion GF-AAS 0.05-0.20 µg/g (1986)
acid digestion GF-AAS 0.25 µg/g Lowe et
wet weight al. (1985)
acid digestion ICP 0.04-0.1 µg/g US EPA
acid digestion ICP-MS 0.025-0.05 µg/g (1986)
acid digestion ICP-AES 0.2 µg/g tissue NIOSH
1 µg/100 ml blood (1987)

Food closed system ASV 0.32 µg/g Holak
digestion (1983)

^a See list of abbreviations on p. xxii.

2.4 Speciation

Developing an objective assessment of the hazard that copper
poses to humans and the environment depends on an intimate
understanding of its bioavailability. Bioavailability, defined as the
extent to which the metal is taken up by an organism upon exposure,
depends on the species of the metal or metallo complex and/or how
easily it can be transformed to a more or less bioavailable species.

2.4.1 Speciation in water and sediments

In natural waters, only very small percentages of copper are
present as the "free" aquo ion (Cu²⁺); rather, most copper is
adsorbed to suspended particles or complexed with various ligands
(Florence & Batley, 1980). Inorganic ligands of greatest importance
are hydroxide, carbonate and, in saline waters, chloride (Bodek et
al., 1988). Binding of copper to fulvic and humic acids and to other
organic compounds can be very strong, so that a large proportion of
dissolved copper is often organically complexed (Neubecker et al.,
1983; Coale & Bruland, 1988; Allen & Hansen, 1996). In air, copper is
present in particulate form. In sediments and soils, most copper is
also on or in particles, either as a constituent of mineral phases or
adsorbed to oxide surfaces or organic matter; formation of copper
sulfide can be particularly important in anoxic sediments (DiToro et
al., 1990). Copper speciation in interstitial water can be affected
by high concentrations of inorganic and organic ligands.

Speciation, the identification and quantitation of a metal in its
various oxidation states, inorganic forms and organometallic
complexes, is afforded through a wide variety of techniques (ICME,
1995).

2.4.1.1 Detection and quantification

a) Electrochemical methods

Electrochemical techniques, especially ASV, have been widely used
to measure the "electrochemically labile" fraction of copper in water
samples, with the assumption that the electrochemically labile
fraction is an approximation of the bioavailable fraction of copper
(Neubecker & Allen, 1983; Bruland et al., 1985; Buckley & van den
Berg, 1986; Morrison & Florence, 1989; Florence et al., 1992; Donat et
al., 1994). It has been shown that if the ASV measurement is carried
out in a manner such that the copper complexing agents in the water
sample affect only the efficiency of electrochemical deposition, but
not the stripping process, then ASV-labile copper correlates very well
with bioavailable copper as measured by algal assay (Florence et al.,
1992). Simple ASV analysis of a water sample at the natural pH where
complexing agents affect both the deposition and stripping processes
tends to underestimate the bioavailable fraction of copper (Zhang &
Florence, 1987; Morrison & Florence, 1989).

Electrochemical titrations using ASV can provide information on
the "complexing capacity" of a water sample, as well as quantitative
data on the conditional formation constants of copper with the ligands
present in the sample. Complexing capacity is defined as the total
concentration of ligands, both organic and inorganic, in a water
sample that will bind copper in nonlabile complexes (Donat et al.,
1994).

b) Equilibration methods

Together with electrochemical methods, equilibration techniques
are among the most popular and successful methods used for speciation
studies. The equilibration methods mostly use ion-exchange resins or
weak inorganic exchangers and complexing ligand. The equilibrium
constant of both the resin and the complex has to be satisfied
simultaneously. The distribution ratio for a fixed resin
concentration is measured in the presence of a competing ligand with
known metal equilibria, which determines the partition coefficient for
the resin. Stability constants and ligand concentrations of unknown
solutions can then be measured (Neubecker & Allen, 1983).

The total concentration of most biologically important trace
metals including copper in seawater is in the range 10^-10-10^-8
mol/litre and hence the concentration of any individual metal organic
complex must be considerably lower. Characterization and
identification of individual compounds at these concentrations in
seawater by chemical techniques is very difficult, if not impossible.
The methodology usually involves first extracting and concentrating
the compounds from sample matrices on to a resin, followed by
fractionation according to different chemical and physical properties.
Since the compounds may not be volatile, the most useful technique is
high performance liquid chromatography (HPLC); alternatively, the
compounds can be made volatile by some derivatization steps then
determined by gas liquid chromatography (GLC), or gas liquid
chromatography-mass spectrophotometry (GLC-MS). Thompson & Houk
(1986) reported an HPLC-ICP-MS method of multielemental analysis and
speciation with a limit of detection of 4 ng of copper. Recently, the
sensitivity for copper was increased by using an ion
chromatography-ICP-MS (IC-ICP-MS) technique (McLaren et al., 1993).
The aluminium hydroxide-cation exchange mini-column technique (Zhang &
Florence, 1987) provides a rapid and simple method for determining
bioavailable copper in both seawater and fresh water samples.

2.4.2 Speciation in biological matrices

The speciation of copper in tissue and blood samples has been
studied (Florence & Batley, 1980; Brouwer et al., 1989; Florence et
al., 1992). In particular, techniques have been developed for the
separation and determination of caeruloplasmin in blood plasma (Lyon &
Fell, 1990) and for metallothioneins in tissue samples (Florence et
al., 1992).

3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

3.1 Natural sources

Metal oxides, silicates and other materials are the building
blocks of rocks forming the earth's crust and it is the weathering of
these rocks that creates soils and sediment. Copper oxide, copper
sulfide and other ores are among these components. Copper, along with
other metals, is distributed through the environment by precipitation
and resulting riverine flows which transport the particles. Depending
on the flow dynamics, these particles settle out and form sedimentary
deposits. Volcanic activity injects dust and particles into the
atmosphere; they then settle out on soil and water surfaces. Wind is
a significant factor in moving metal-laden soil particles around the
land surface of the earth, which they can also reach from atmospheric
sources by both wet (rain washout) and dry deposition. An important
source of copper in aquatic sediments is from dead organisms which
settle out and contribute both copper and organic material. This can
be a significant source in the oceans, for example.

Copper has a natural abundance of approximately 60 mg/kg in the
earth's crust and 2.5 × 10^-4 mg/litre in the sea (Lide & Frederikse,
1993). It occurs naturally in many minerals such as cuprite (Cu₂O),
malachite (Cu₂CO₃.Cu(OH)₂), azurite (2CuCO₃.Cu(OH)₂),
chalcopyrite (CuFeS₂), chalcocite (Cu₂S), and bornite (Cu₅FeS₄).
Copper is also found naturally in its metal form (Tuddenham & Dougall,
1978). The copper content of ore deposits ranges from 0.5 to 5% by
weight, whereas igneous rock contains 0.010% (Duby, 1980) and
crystalline rock 0.0055% by weight. The most important sources of
copper are chalcocite, chalcopyrite and malachite (Weant, 1985).

Figures from Cannon et al. (1978) indicate a range of 4-200 mg
Cu/kg and a range of mean concentrations of 2-90 mg Cu/kg in igneous
and sedimentary rocks. Nriagu (1989) estimated mean worldwide
emissions of copper from natural sources as follows: windblown dusts,
0.9-15 × 10³ tonnes; forest fires, 0.1-7.5 × 10³ tonnes; volcanic
particles, 0.9-18 × 10³ tonnes; biogenic processes, 0.1-6.4 × 10³
tonnes; sea salt spray, 0.2-6.9 × 10³ tonnes.

Average background concentrations of copper in air in rural areas
range from 5 to 50 ng/m³. Copper levels in seawater of 0.15 µg/litre
and in freshwater of 1.0-20 µg/litre are found in uncontaminated areas
(Nriagu, 1979b). Background levels of copper in uncontaminated
sediments range from 800 to 5000 mg/kg (dry weight) (Forstner &
Wittmann, 1979). Copper levels in marine sediments range from 2 to
740 mg/kg (dry weight). Median copper concentrations in uncontaminated
soil were reported to average 30 mg Cu/kg with a range of 2-250 mg/kg
(Bowen, 1985). Detailed information on concentrations in the
environment is presented in section 5.1. Copper is found as a natural
component of foods eaten by humans and animals.

3.2 Anthropogenic sources

Anthropogenic sources of copper include emissions from mines,
smelters and foundries producing or utilizing copper, zinc, silver,
gold and lead. Environmental copper can also arise from the burning
of coal for power generation and from municipal waste incinerators. A
major release of copper to land comes from mine tailings and
overburden from mining operations. Other anthropogenic sources of
copper include its use as an antifouling agent in paints, agriculture
(fertilizers, algicides, feed supplements) and animal and human
excreta (animal manure and human sewage sludge). Copper is also
intentionally released into some water bodies to control the growth of
algae (Slooff et al., 1989; ATSDR, 1990).

Although it was estimated that 66% of copper emissions to the
environment in 1983 were from anthropogenic sources (Nriagu, 1989),
there is evidence that industrial emissions are decreasing owing to
stringent controls developed in facilities manufacturing and using
copper (Dann, 1994).

3.2.1 Production levels and processes

The mining and refining of copper takes place on all six
continents. Mines in Chile, USA and Canada account for over 50% of
the annual worldwide production of 11 × 10⁶ tonnes of refined copper
metal (ICSG, 1996). Other major areas for copper mining include
Russia, Australia, Zambia, Indonesia, Peru, China and Poland. It is
estimated that about 40% of the copper used worldwide (approximately
15 × 10⁶ tonnes) comes from recycled metal (ATSDR, 1990). Release of
airborne copper from smelters is currently one of the major sources of
copper to the environment.

The majority of copper metal is produced by smelting of the
copper sulfide ore followed by electrolytic refining (ATSDR, 1990).
Some 10⁶ tonnes were produced in Chile and North America using
solvent extraction technology. The process involves extraction of
copper from acidic leach solutions using organic reagents followed by
electrolytic extraction. The principal sources of copper for this
process are conventional mining of oxide ores in open pits, leaching
of mine dump low-grade ore, and mill tailings and mine water run-off.
Extraction of mine tailings and dumps in this way reduces the
environmental impact of mine wastes by reducing the copper
concentrations in these sources.

3.3 Copper use

The world uses approximately 15 × 10⁶ tonnes of copper a year.
Of this about one-third is derived from recycled metal, and the rest
is supplied from the mining of ore bodies and refining of the
extracted copper.

The unique combination of properties of copper, including
durability, ductility, malleability and electrical and thermal
conductivity, determine its uses in a vast range of applications. A
summary of these uses in the USA, Western Europe and Japan is given in
Table 3, compiled from Marco (1989).

Worldwide, the largest use of copper is in electrical wire and
cable and other electronic applications, which can account for as much
as 65% (9.75 × 10⁶ tonnes) of total annual copper consumption.
Rolled copper is also extensively used in architectural applications
for roofing, rainwater goods and cladding, while rolled copper and
brass are also used for vehicle radiators. Overall, the major
industrialized countries consume over 1.5 × 10⁶ tonnes of rolled
product per year. Approxi mately 15% (2.25 × 10⁶ tonnes) of copper
is used annually in building and construction, including plumbing,
architectural applications such as roofing, guttering and flashing,
and in fixtures and fittings. The remaining 20% (3 × 10⁶ tonnes)
goes to transport equipment, air-conditioning and refrigeration as
well as general and light engineering uses such as machine parts, and
process equipment, coinage, ordnance and consumer goods, such as
domestic appliances as well as production of bronze and brass alloys.

Extruded brass is a raw material for the forging and machining
sectors, and is turned into a wide range of components such as taps,
valves and water fittings, and instrument and machine parts. Over 1.7
× 10⁶ tonnes of extruded copper alloy products are consumed by the
major industrialized countries annually.

Tubes in copper and copper alloys are widely and increasingly
used for domestic plumbing and heating systems, air conditioning,
refrigeration and industrial applications. Over 1.5 × 10⁶ tonnes of
tubes are consumed annually by the major industrialized countries.

A small percentage of copper production goes into the manufacture
of copper compounds, particularly copper sulfate which is used
primarily for industrial and agricultural purposes. In industry,
copper sulfate is used as an activator in the froth flotation of
sulfide ores, production of chromated copper arsenate wood
preservatives, electroplating, azo-dye manufacture, as a mordant for
textile dyes, in petroleum refining and in the manufacture of other
inorganic and organometallic compounds (ATSDR, 1990). Other copper
compounds find uses as pigments, paints, dyes, glasses, catalysts and
fungicides. Copper is finding increasing use as the active ingredient
in antifouling paints. In this context it is also used in paints for
operating theatres and other hospital facilities to reduce inadvertent
contamination of surfaces and transmission of disease-causing
organisms.

Table 3. Copper consumption in 1988^a (in thousands of tonnes)

Use Building and Electrical/ Industrial
construction electronics

Copper wire 0 4293 0
Copper rod 5 164 34
Copper sheet and strip 240 140 225
Copper tube 551 0 424
Alloy wire 7 9 65
Alloy rod 338 114 462
Alloy sheet and strip 66 123 443
Alloy tube 14 8 110
Castings 142 58 292

Totals 1363 4909 2055

^a Based on figures from the USA, western Europe and Japan (about 75%
of world consumption of 11 090 000 tonnes) (Marco, 1989)

In agriculture, copper compounds, especially copper sulfate, are
used as fungicides, pesticides, algicides, nutritional supplements in
animal feeds, and fertilizers. Copper fungicides are used to treat
foliage, seeds, wood, fabric and leather as a protectant against
blights, downy mildews and rusts (ATSDR, 1990). One of the principle
mixtures used to treat foliage for mildew and fungal infections is the
Bordeaux mixture used to spray vines which typically contains 0.05-2%
copper neutralized with soda lime (Pimentel & Marques, 1969). Copper
sulfate is used throughout the world to kill and inhibit the growth of
algae in municipal reservoirs, irrigation equipment and piping,
swimming pools and industrial cooling systems. It is also used in
animal feed additives and growth promoters, as well as for disease
control in livestock and poultry (Grant et al., 1990).

Copper enjoys limited use in human and veterinary medicine,
having been largely replaced by other compounds and treatments.
Copper is, however, a major constituent of many of the metallic
amalgams (e.g. mercury amalgams) used in dentistry. It is also used
to prepare intrauterine devices (IUDs).

4. ENVIRONMENTAL TRANSPORT AND DISTRIBUTION

4.1 Transport and distribution between media

The information reviewed in this section describes the environ
mental fate of copper. The factors affecting the distribution of
copper in air, water, sediment and soil are first described. This is
followed by a review of the factors influencing the bioaccumulation of
copper. This review is not intended to be exhaustive but rather to
present selected representative papers.

4.1.1 Air

Copper is released to the atmosphere in the form of particulate
matter or adsorbed to particulate matter. It is removed by
gravitational settling (bulk deposition), dry deposition (inertial
impaction characterized by a deposition velocity), washout by rain
(attachment to droplets within clouds), and rainout (scrubbing action
below clouds) (Schroeder et al., 1987). Removal rate and distance
travelled from the source depend on source characteristics, particle
size and wind velocity. Gravitational settling governs the removal of
large particles (> 5 µm), whereas smaller particles are removed by
other forms of dry and wet deposition. The relative importance of wet
as compared to dry deposition generally increases with decreasing
particle size (ATSDR, 1990).

Chakrabarti et al. (1993) analysed samples of rainwater (pH 5.3)
and snow (pH 4.7) in Canada; the total copper concentrations were 30.3
µg/litre in the rainwater and 24.6 µg/litre in the snow. In the
rainwater sample 98.3% of the copper was in the soluble phase (< 0.45
µm) and 1.7% in the particulate phase (> 0.45 µm) whereas in the snow
sample 80.5% was found in the particulate phase and 4.8% in the
soluble phase. Another snow sample (pH 3.9) was analysed and revealed
a copper concentration of 5.7 µg/litre with 4.7 µg/litre in the
soluble phase and 1.08 µg/litre in the particulate phase. Kinetic
results suggested that the copper in the snow sample was probably
bound to different sites having different bonding energies in
polyfunctional complexing agents. Four different copper species
having different dissociation rate constants were observed
(3.1 × 10^-2, 1.6 × 10^-3, 6.2 × 10^-5 and 8.8 × 10^-6/s). Cheng et al.
(1994) found that the distribution of copper species in rainwater
collected in Ottawa, Canada, was very similar to that in the
previously reported snow sample. The rainwater sample contained 7.10
µg Cu/litre of which 2.03 µg/litre was in the particulate phase and
5.07 µg/litre in the soluble phase (< 0.45 µm). The scavenging ratio
of the copper concentration in precipitation (mg/litre) to air
concentrations (µg/m³) for large particles displays a seasonal
variation reflecting the more effective scavenging of snow compared
with rain (Chan et al., 1986).

There is large temporal and spatial variability in copper
deposition. Schroeder et al. (1987) reviewed deposition rates and
washout ratios for copper. Copper deposition rates in urban areas

were estimated to be 0.119 and 0.164 kg Cu/ha per year for dry and wet
deposition, respectively. Bulk deposition was reported to range from
0.002 to 3.01 kg Cu/ha per year. In rural areas bulk deposition was
reported to range from 0.018 to 0.5 kg Cu/ha per year and wet
deposition was 0.033 kg Cu/ha per year. The washout ratio is
114 000-612 000 (µg Cu/m³ rain)/(µg Cu/m³ air) [(140-751 µg Cu/kg
rain)/(µg Cu/kg air)].

Ottley & Harrison (1993) calculated the dry deposition flux of
copper to the North Sea to be 350 tonnes Cu/year. Migon et al. (1991)
studied the input of copper through rainfall and dry deposition to the
Ligurian Sea (Mediterranean) over a period of two years. The total
flux was calculated to be 1.85 kg Cu/km² per year. A mean yearly
atmospheric input for copper was calculated at 98 tonnes. Fergusson &
Stewart (1992) estimated deposition flux for copper in the insoluble
component of bulk deposition derived from Christchurch city, New
Zealand. Copper fluxes followed approximately exponential decay
curves away from the city. Deposition rates varied from 0.83 µg
Cu/m² per day (a remote site) to 21 µg Cu/m² per day (an inner city
site). In the city and nearby rural areas soil is not a major source
of atmospheric copper, whereas at remote sites atmospheric copper is
mostly soil-derived.

The atmospheric wet deposition of copper at Chesapeake Bay, USA,
was examined during 1990 and 1991. The monthly integrated atmospheric
fluxes exhibited a high degree of spatial and temporal variability.
The arithmetically averaged annual wet flux was 260 µg Cu/m²
(Scudlark et al., 1994), and this was derived predominantly from
anthropogenic sources. Wu et al. (1994) calculated the dry deposition
flux for Chesapeake Bay to be 290-810 µm Cu/m² per year. Dry
deposition fluxes for Lake Michigan were estimated at 690 and 800 µm
Cu/m² per year.

Migon (1993) compared riverine and atmospheric inputs of copper
with the Ligurian Sea (Mediterranean). Atmospheric inputs were found
to be higher, with a ratio of 16.3 to 32.6.

Chan et al. (1986) reported that in southern Ontario, Canada
during 1982, the mean concentration of copper in precipitation was
1.57 µg Cu/litre of which 1.36 mg Cu/m² was from wet deposition. The
mean concentrations of copper in precipitation were 1.36 and 1.58 µg
Cu/litre for central and northern Ontario, respectively. In both
areas the annual wet deposition averaged 1.13 mg Cu/m².

Remoudaki et al. (1991) calculated the seasonal copper
atmospheric deposition to the western Mediterranean. Atmospheric
deposition of copper during the wet season ranged from 0.0004 to
0.0005 µg Cu/cm² per day and during the dry season 0.0007 to 0.0014
µg Cu/cm² per day.

Gorzelska (1989) analysed snowpack samples from 18 sites in the
vicinity of Inuvik, Canada during 1985 and 1986. Copper
concentrations ranged from 0.1 µg Cu/kg 20 km north of the town to

0.54 µg Cu/kg near a power plant. In all the samples the trace metals
were enriched with respect to crustal material. Mass balance
calculations have shown that most of the copper emitted by the local
sources is transported outside the immediate vicinity of the town.

4.1.2 Water and sediment

Several processes influence the fate of copper in aquatic
systems. These include complexation to inorganic and organic ligands,
sorption to metal oxides, clays, and particulate organic material,
bioaccumulation and exchange between sediment and water (Stiff, 1971;
Callahan et al., 1979).

Much of the copper discharged to water is in particulate form and
tends to settle out, precipitate out or be adsorbed by organic matter,
hydrous iron, manganese oxides and clay in the sediment or water
column. Equilibrium is normally reached within 24 h. Copper
discharged into a river leading into Chesapeake Bay contained 53 µg
Cu/litre, of which 36 µg/litre was in the form of settleable solids
(Helz et al., 1975). The concentration of copper 2-3 km downstream
from the outfall had fallen to 7 µg/litre. Copper in particulate form
includes precipitates, insoluble organic complexes and copper adsorbed
to clay and other mineral solids (Stiff, 1971).

Owing to unacceptable past practices, Macquarie Harbour on the
west coast of Tasmania, Australia contains dissolved copper levels as
high as 560 µg/litre as a result of riverine transport in dissolved
and particulate forms from the Mount Lyell copper mine (Carbon, 1996).
Some 97 × 10⁶ tonnes of mine tailings and 1.4 × 10⁶ tonnes of slag
were deposited into the Queen and King river system over a 78-year
period before closure of the mine.

The copper(I) ion is unstable in aqueous solution, tending to
disproportionate to copper(II) and copper metal unless a stabilizing
ligand is present (Callahan et al., 1979). The only cuprous compounds
stable in water are insoluble ones such as the sulfide, cyanide and
fluoride. In its copper(II) state, copper forms coordination
compounds or complexes with both inorganic and organic ligands.
Ammonia and chloride ions are examples of species that form stable
ligands with copper. Copper also forms stable complexes with organic
ligands such as humic acids. In seawater, organic matter is generally
the most important complexing agent. Samples collected from the
surface waters (< 200 m) of the northeast Pacific revealed that over
99.7% of the total dissolved copper was associated with organically
complexed forms. At depths of 1000 m approximately 50-70% of the
copper was in the organically complexed form. Copper complexation
gave rise to very low cupric ion activities in surface waters, around
1 pg Cu²⁺/litre. The authors reported that two classes of
copper-binding ligands were identified: an extremely strong ligand at
low concentrations dominated in surface waters and a weaker class of
ligand at higher concentrations was found throughout the water column
(Coale & Bruland, 1988).

Tan et al. (1988) collected freshwater river samples from the
Linggi river basin, Malaysia. Samples were separated into colloidal
fractions and soluble fractions. Soluble fractions were classified
according to the lability of the copper forms in the water.
Categories range from very labile (e.g. free metal ion) to nonlabile
(e.g. colloidally bound metal). In this study 18-70% of the dissolved
copper was moderately labile and 13-30% was slowly labile.

Copper in the fresh and estuarine waters of the Cochin estuary,
India, was found to be extensively associated with organic colloidal
matter. The relationship between exchangeable and total particulate
copper did not show a significant correlation during the study,
emphasizing the role of lattice-incorporated copper as distinct from
particulate scavenged/adsorbed exchangeable copper (Shibu et al.,
1990).

A detailed study of the Tamar estuary, United Kingdom, revealed a
decrease in the alpha-coefficient for complexation of Cu²⁺ by natural
organic ligands (log alpha _CuL) from 10.8 to 8.3 with increasing
salinity, demonstrating that major cations compete with copper for the
complexing sites. The free Cu²⁺ concentrations were very low (16.2
< pCu(II) < 18.2) throughout the estuary even though the total
dissolved copper concentrations were high (up to 300 nmol/litre),
probably because of complexation to dissolved organic complex (Van den
Berg et al., 1990).

Giesy et al. (1986) isolated dissolved organic carbon from nine
surface waters in the southeastern USA and found that the binding of
copper by humate occurs with different strengths at a number of sites,
the binding strength at the sites varying by two orders of magnitude,
dependent on the ratio of copper to total organic ligand.

Organic compounds form complexes with 94-98% of dissolved copper
in the surface waters of the North Sea. In all samples strong
copper-chelating compounds were found at concentrations of 4-10 µg
Cu/litre (60-150 nmol/litre). The major inorganic complexes in the
seawater samples were CuCO₃⁰ (60%), CuOH⁺ (16%) and Cu(OH)₂⁰
(16%) (Van den Berg, 1984).

Mackey & Higgins (1988) found that the strong copper-complexing
capacity of seawater can vary by more than three orders of magnitude.
Copper-complexing capacity was related to the phytoplankton biomass.
High values were associated with high phytoplankton mass, whereas when
the biomass was low the copper-complexing capacity was also low. The
authors found that in nutrient-limiting, oligotrophic waters of low
average productivity the copper-complexing capacity was variable.

Midorikawa et al. (1992) identified three classes of natural
organic ligands in coastal seawater classified by differences in their
complexing abilities for copper.

Gardner & Ravenscroft (1991) studied the behaviour of copper
complexation in rivers and estuaries of northeast England. They found
that copper speciation in rivers and estuaries is dominated by organic
complexation. The authors found a mixture of ligands of different
affinities for copper in natural waters. The complexation of copper
discharged to rivers and estuaries occurred very rapidly. Complexation
capacities were consistently in the range 10-25 µg Cu/litre (150-400
nmol/litre). The copper-complexing capacity of Linggi river water
(Malaysia) was in the range 26-74 µg Cu/litre (410-1160 nmol/litre)
(Tan et al., 1988).

Sharma & Millero (1988) measured the oxidation of copper(I) in
air-saturated solutions of seawater as a function of pH (5.3-8.6),
temperature (5-45 °C) and salinity (5-44%). The rate of reaction
increased with pH and temperature, and decreased with salinity (ionic
strength). The results indicate that the rates are controlled by the
concentration of Mg²⁺, Ca²⁺, Cl^- and HCO₃^- through complex
formation and ligand exchange.

Bradley & Cox (1988) found that 80% of the measurable copper in
standard river sediment SRM 1645 was in the organic fraction. In
Yamuna river sediments, India, copper is mainly associated with the
organic matter owing to its high complexing tendency for organic
matter. A high percentage of copper is also found in the residual
fraction, and much lower concentrations are associated with the
carbonate and iron-manganese oxide phases (Gadh et al., 1993).

Calmano et al. (1993) studied the mobilization of copper from
contaminated sediments. The dominant mobilizing factor was pH with
mobilization increasing with increasing acidity. At pH values
of < 4.5 there was a strong influence of pH on mobilization. At
identical pH values the mobilized portions of copper from the oxic
sediment are tenfold higher than those from anoxic sediment.

Samanidou & Fytianos (1990) estimated a mobilization of 10-15% of
copper due to NTA and EDTA in two rivers in northern Greece, with no
consideration of the biodegradation of metal complexes. Samanidou et
al. (1991) estimated that humic substances (~2-3 mg/litre) were able
to cause the long-term release of 70-80% of copper in the same rivers.
In experimental studies copper was remobilized by synthetic complexing
agents more readily than other metals tested (cadmium, lead, manganese
and chromium).

4.1.3 Soil

In the terrestrial environment, a number of important factors
influence the fate of copper in the soil. These include the nature of
the soil itself, its pH, the type and distribution of organic matter,
the soil redox potential, the presence of oxides, the base status of
the soil and its cation exchange capacity (CEC), the rate of litter
decomposition and the proportions of clay to silt to sand particles.
The residence time of copper in the soil is also a function of overall
climate and of the vegetation present at a site.

Most copper deposited on soil from the atmosphere, from
agricultural applications and from sewage sludge amendments is
strongly adsorbed to the upper few centimetres of the soil. It is
especially bound to the organic matter, as well as being adsorbed by
carbonate minerals and hydrous iron and manganese oxides. Copper
binds more strongly than most other metals and is less influenced by
pH as a result. The greatest amount of leaching of copper occurs from
sandy soils, compared with clays and peats, whereas acidic conditions
favour copper leaching to the groundwater from the soil.

Lehmann & Harter (1984) studied the kinetics of copper desorption
from the A horizon of Paxton soil (surface soil), USA, following
addition of copper at rates ranging from 100 to 500 mg/kg. When 500
mg Cu/kg is added to this soil, a