113
Chemical analysis of water
updated by
BSc (Hons1), MSc, PhD, DSc, FRACI, C Chem. Graeme E Batley
BSc (Hons1), PhD, C Chem. Stuart L Simpson
by
Colin F Gibbs
Gastone J Fabris
Andrew P Murray
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Author information
Dr Graeme Batley is Chief Research Scientist and past Director of the Centre for
Environmental Contaminants Research, CSIRO Land and Water at Lucas Heights near
Sydney. He has BSc (Hons1), MSc, PhD and DSc degrees from the University of New
South Wales. He is well known for his research on the analytical and environmental
chemistry of contaminants in natural waters and sediments, in particular on metal
speciation and bioavailability. He has authored over 380 research publications. He was
a recipient of both Environment and Analytical Medals of the Royal Australian Chemical
Institute, and the CSIRO Chairman’s Medal. In 2006, he was jointly awarded the Land
and Water Australia Eureka Prize for Water Research.
CSIRO Land and Water, Lucas Heights, NSW 2234
Email: [email protected]
Dr Stuart Simpson is Senior Principal Research Scientist at the Centre for
Environmental Contaminants Research, CSIRO Land and Water at Lucas Heights near
Sydney. He has BSc (Hons1) and PhD degrees from Canterbury University,
Christchurch, New Zealand. He is an active researcher in the field of sediment quality
assessment and has authored over 150 research publications. He has a broad interest
in the analytical and environmental chemistry of contaminants in aquatic environments,
in particular, the reactivity of metal pollutants and processes controlling contaminant
bioavailability and effects in both surface waters and sediments. In 2006, he was jointly
awarded the Land & Water Australia Eureka Prize for Water Research, and the CSIRO
Medal for Research Achievement.
CSIRO Land and Water, Lucas Heights, NSW 2234
Email: Stuart.simpson@csiro.
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TABLE OF CONTENTS
ABBREVIATIONS ........................................................................................................................
GLOSSARY ...................................................................................................................................
INTRODUCTION – WATER AND ITS IMPORTANCE IN POLICY AND LAW... [113.70]
Introduction.................................................................................................................... [113.70]
The chemical properties of water ................................................................................. [113.80]
Water impurities ............................................................................................................ [113.90]
Murcury accumulation ................................................................................................. [113.100]
Explanation of Table 1................................................................................................. [113.110]
Environment protection policies, beneficial uses and water quality criteria ............... [113.130]
Licensing ..................................................................................................................... [113.140]
The role of water analysis........................................................................................... [113.150]
Water analysis in environmental law .......................................................................... [113.160]
SAMPLING AND SAMPLE HANDLING ..................................................................................
Samplings.................................................................................................................... [113.180]
Sampling handling....................................................................................................... [113.190]
Replication in sampling and analysis.......................................................................... [113.200]
Detection limits............................................................................................................ [113.210]
QUALITY ASSURANCE ............................................................................................. [113.250]
NATA accreditation of laboratories.............................................................................. [113.260]
Standards Australia and Australian standard methods............................................... [113.270]
Professional qualifications........................................................................................... [113.280]
Appointment of analysts.............................................................................................. [113.290]
METHODS OF ANALYSIS ......................................................................................... [113.300]
Overview ..................................................................................................................... [113.300]
Types of waters........................................................................................................... [113.310]
Concentrations of various chemicals in water ............................................................ [113.320]
Types of analysis ........................................................................................................ [113.330]
Conductivity................................................................................................................. [113.340]
Salinity measurement.................................................................................................. [113.350]
Ion-selective electrodes (ISE) ..................................................................................... [113.360]
pH measurement......................................................................................................... [113.370]
The dissolved-oxygen meter....................................................................................... [113.380]
Dissolved oxygen by Winkler titration......................................................................... [113.390]
Biological oxygen demand (BOD) and chemical oxygen demand (COD) ................. [113.400]
Colorimetric methods – nitrogen, phosphorus and surfactants.................................. [113.410]
Determining anionic surfactants.................................................................................. [113.420]
Chlorophyll a ............................................................................................................... [113.430]
Oil-spill fingerprinting................................................................................................... [113.450]
Trace metal determination by spectrometric methods................................................ [113.490]
Atomic absorption spectrometry (AAS)....................................................................... [113.493]
Inductively-coupled plasma atomic emission spectrometry (ICPAES) and inductivelycoupled plasma mass spectrometry (ICPMS) ....................................................... [113.495]
The ICP method.......................................................................................................... [113.497]
Detection limits and analytical working range ............................................................ [113.510]
Interferences ............................................................................................................... [113.520]
Application to water analysis ...................................................................................... [113.530]
Trace metal determination by stripping voltammetric methods .................................. [113.550]
Anodic stripping voltammetry (ASV) ........................................................................... [113.560]
Adsorptive cathodic stripping voltammetry (CSV) ...................................................... [113.590]
Application to water analysis ...................................................................................... [113.600]
ASV and CSV ............................................................................................................. [113.610]
Metal speciation and bioavailability ............................................................................ [113.630]
Analytical determination of metal speciation in natural waters .................................. [113.640]
Chromatography.......................................................................................................... [113.670]
Sample preparation and clean-up............................................................................... [113.680]
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Gas chromatography (GC).......................................................................................... [113.690]
Gas chromatography/mass spectrometry (GC/MS) and GC/FTIR............................. [113.720]
Liquid chromatography................................................................................................ [113.750]
Ion chromatography .................................................................................................... [113.780]
BIBLIOGRAPHY ..........................................................................................................................
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ABBREVIATIONS AND GLOSSARY
ABBREVIATIONS AND GLOSSARY
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Abbreviations
AAS .................................................atomic absorption spectrometry
ANZECC .........................................Australian and New Zealand Environment and
Conservation Council
APHA ..............................................American Public Health Association
ARMCANZ .....................................Agriculture and Resource Management Council of Australia
and New Zealand
ASV .................................................anodic stripping voltammetry
CRM ................................................certified reference material
ICPAES............................................inductively coupled plasma atomic emission spectrometry
ICPMS .............................................inductively coupled plasma mass spectrometry
ISO...................................................International Standards Organisation
NATA...............................................National Association of Testing Authorities
NBS .................................................National Bureau of Standards (American)
NIST ................................................National Institute of Standards and Testing
ng .....................................................nanogram or 10-9 (one trillionth) of a gram
PAH .................................................polycyclic aromatic hydrocarbon
ppb ...................................................parts per billion (equals micrograms per kilogram or per
litre of water)
ppm ..................................................parts per million (equals milligrams per kilogram or per
litre of water)
RACI................................................Royal Australian Chemical Institute
g .................................................. imicrogram or 10-6 (one billionth) of a gram
G
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GLOSSARY
Glossary
analyte — the material being determined in a sample (eg cadmium).
analytical curve — a graphical plot of the relation between the measured response and the
concentration (or mass) of the analyte. Also known as a calibration curve.
accuracy — in analysis, the closeness of agreement between the true value for an analyte in a
sample and the mean value obtained for that analyte following a number of determinations.
anion — a negatively-charged chemical species such as chloride (Cl-).
aromatic — aromatic compounds are a class of organic chemicals including a particularly
stable unsaturated ring structure, usually of six carbons atoms. The simplest is benzene (C6H6).
Other monoaromatics include toluene and xylene. Polycyclic aromatics have several such rings
fused together, eg benzo[a]pyrene. Aromatics containing only carbon and hydrogen are the
well-known “aromatic hydrocarbons”.
arithmetic mean — (the simplest form of average) is the sum of the measurements divided by
the number of measurements.
atom — one of the 117 fundamental chemical entities which cannot be subdivided by chemical
means.
blank — the test reagents without the addition of a sample/analyte. Generally, the result of this
blank determination is subtracted from the sample results to allow for such things as trace
amounts of analyte in the chemicals used in the test.
calibration — the process of determining the relationship between the instrument response (eg,
absorbance or current) and the concentration or mass of the analyte, using a set of calibration
solutions and a matrix solution.
calibration curve — see “analytical curve”.
calibration solutions — a set of reference solutions containing different concentrations of the
analyte prepared by appropriate dilution of a stock solution.
cation — a positively-charged chemical species such as a sodium ion (Na+).
certified reference material — a sample of material that has been analysed at a number of
competent laboratories to certify the concentration of one or more of its analytes. Often
purchased from such organisations as the National Institute of Standards and Technology.
chromatography — a general method of separating the components of a mixture by distribution
between a moving phase and a stationary phase.
chromatogram — the resulting chart record showing the results of chromatography of a
sample.
compound — a chemical composed of more than one type of atom such as sodium chloride
(NaCl).
detection limit — the minimum concentration of analyte that can be detected with a stated
statistical certainty.
complex, complexation — in aqueous solutions containing dissolved metal salts, the metal ions
are surrounded by water molecules which may be more or less firmly bound to them. In these
circumstances, the metal ions are said to be hydrated. A complexation reaction involves the
replacement of one or more of these water molecules with some other entity, usually an
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organic compound referred to, in this context, as a ligand. This may be represented as follows:
M(H2O)n + L <– – – –> M(H2O)n-1L + H2O
where:H2O = water;L = molecule or ion (which is called a ligand when it behaves in this
way)n = number of water molecules around the central ionPositive and negative charges are
not shown.
element — a chemical consisting of only one type of atom such as chlorine (Cl2).
geometric mean — is the antilogarithm of the mean of the logarithms of the measurements.
harmonic mean — the reciprocal of the arithmetic mean of the reciprocals of the
measurements.
hydrocarbon — a chemical compound consisting of hydrogen and carbon only.
immiscible — a term applied to a pair of liquids, meaning that they do not mix freely together.
An obvious example is oil and water.
inorganic chemical — a chemical compound or element not based on carbon and its unique
carbon-carbon bonding.
interferant — a substance which interferes with the analysis of another substance, either by
responding positively or by inhibiting the response by the analyte.
ionisation — the production of positively- or negatively-charged chemical species.
ligand — an ion or molecule that binds to a metal atom to form a complex. See complex,
complexation
matrix solution — a solution that contains all chemicals used in the preparation of the sample
solution plus all constituents in the sample that influence the determination, in similar
concentrations as in the sample solution.
maximum — the highest figure obtained under the sampling regime specified.
mean — the average. (See “arithmetic”, “geometric” and “harmonic means”.)
median — the value such that half the sample results lie above and half lie below it.
micromolar (M) — one millionth of molar concentration, where molar means the molecular
weight in grams dissolved in one litre.
molecule — one unit of a chemical compound (such that it cannot be subdivided without
becoming chemically different).
organic chemical — a compound based on carbon atoms bonded to each other and to other
elements, particularly hydrogen and oxygen.
percentile — the 80th percentile, for example, is that figure where 80% of measurements (or
samples) lie below it. An example of this is one of the criteria for faecal coliform bacteria: a
geometric mean of 200 organisms per 100 ml and an 80 percentile value of not more than 400
organisms per 100 ml. That is, not more than 20% of samples may exceed 400 organisms per
100 ml, (as well as the criterion of a geometric mean not above 200). Sampling regime is
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GLOSSARY
specified as at least five samples in not more that 42 days. (Note, these figures are guidelines
for only one category of water in one State.) It may be seen that the 50th percentile is the same
as the median.
pH — a measure of acidity or alkalinity. More precisely, the pH is the negative logarithm of
the hydrogen ion concentration. A pH less that 7 is acidic, a pH greater that 7 is alkaline. A
water sample at pH 6 has 10 times the acid or hydrogen ion concentration than does one at pH
7.
phase — a physically distinct form of matter, that is, a body of material characterised by its not
mixing with another phase. For example, a system might have three phases: solid, liquid and
gas. Also, oil floating on water would be two separate liquid phases (aqueous phase and
organic phase).
photoionisation — ionisation of a compound caused by light.
phytoplankton — microscopic plants free-floating in the water.
polar — this description of a chemical, including a solvent, means that its molecules either
carry electrical charges normally, or easily have electrical charges induced by the presence of
ions. For example, as solvents, water is very polar, whereas hexane, a saturated hydrocarbon. is
very non-polar. Very polar solvents are good at dissolving salts, which carry electrical charges.
Non-polar solvents dissolve non-polar materials, eg, petrol dissolves tar.
precision — in analysis, the closeness of agreement between results obtained by a number of
repetitive determinations. The precision may be determined by multiplying the standard
deviation for 30 or more determinations by three.
resonance wavelength — a wavelength corresponding in energy to the transfer of an electron
between the ground state and a higher energy level of an atom.
sample solution — a solution prepared from a test solution of the sample submitted for
analysis.
sensitivity — the extent to which an analytical technique responds to a given quantity of
analyte (the slope of the analytical curve).
solvent — the liquid in which chemicals are dissolved. In the context of water analysis, a
solvent is often (incorrectly) used for an organic liquid that does not mix fully with water.
spectrum — a graph of an optical property (usually absorption) against the wavelength (or
frequency) of light. Also, similar presentations of results such as the mass spectrum that is the
abundance of ions plotted against the mass of the ions.
standard deviation — a mathematical measure of the spread or scatter of results from a series
of measurements.
standard solution — a reference solution containing the analyte in a known concentration, used
in calibrating a series of measurements.
stock solution — a reference solution containing the analyte in an appropriately high, known
concentration, from which a range of standard solutions is prepared.
titration — a form of quantitative analysis in which the analyst measures the volume of one
solution needed to exactly react with a known volume of another.
volatile — a substance is described as volatile if it easily forms a gas or vapour.
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INTRODUCTION – WATER AND ITS IMPORTANCE
IN POLICY AND LAW
[113.70] Introduction
An old friend tells a story of a lawyer trying to simplify matters in an environmental pollution
case. He had been given a list of pH measurements for an industrial discharge over the course
of a year. To simplify matters, he added them all together and expounded: “Do you realise,
your Worship, that over the last 12 months the defendant discharged a total pH of 3,987!” This
chapter is aimed particularly at anyone who does not find that immediately hilarious or tragic.
Water analysis is important because the condition of water is vital to the health of the planet
and its plants and animals (including humans). We as a species depend utterly on water both
directly and via our dependence on other animals and plants. We drink it, catch fish from it,
water stock, irrigate crops and use vast amounts of water in industry. Many of the fundamental
processes allowing life on earth take place in water, eg, the regeneration of oxygen from
carbon dioxide which takes place in the oceans as well as in the forests. Seawater is even used
as a raw material for chemical production, the most obvious product being salt. All uses and
natural processes have their different requirements for water quality, often on a scale of
“purity”.
Water itself is an exceptional chemical compound. Everyone knows its formula “H2O”,
signifying its composition of two hydrogen atoms bound to one oxygen atom. However, its
low molecular weight of 18 would normally correspond to a gas, not a liquid. It is only the
involvement of hydrogen bonding that keeps it as a liquid at normal temperatures. The
chemical bonds between the hydrogens and the oxygen within the water molecule are based on
the sharing of negatively-charged electrons between these atoms. The oxygen has a stronger
“pull” for the electrons than do the hydrogen atoms and takes a greater share of them. This
gives a partial negative charge to the oxygen and a partial positive charge to the hydrogen
atoms.
Electrostatic attraction between the oxygen of one molecule and a hydrogen of another (called
“hydrogen bonding”) causes temporary “clumping” of molecules (see Figure 1), which keeps
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water as a liquid at normal temperatures. At higher temperatures, of course, these interactions
are overcome, the molecules shake apart and eventually become gas (steam). Conversely, at
low temperatures the aggregation of molecules becomes more permanent and the water freezes
to ice. Without this hydrogen bonding, the Earth would not be blessed with liquid water, and
life as we know it would be impossible.
[113.80] The chemical properties of water
Even the freezing of water is exceptional, and beneficial to life. All other materials contract in
volume on cooling, thus increasing in density. Water does so until it reaches 4°C (degrees
Celsius). At this point, further cooling causes expansion, decreasing the water’s density. This
means that at temperatures down to 4°C, cold weather causes cooler water from the surface to
sink and mix. However, below that temperature the colder water “floats” at the surface.
Therefore, when ice is formed, it floats on the surface rather than sinking to the bottom. This
plays an important role in insulating lakes, eg, from the effects of freezing weather. If water
behaved like other materials, with ice sinking, many water bodies would eventually freeze
solid, making life impossible for animals.
The chemical properties of water are also exceptional, in particular its ability to dissolve a
wide range of other chemicals. This, like its physical properties, is largely dependent upon the
electrostatic properties of the oxygen–hydrogen bond. In short, the properties of water border
upon the magical.
The water that covers so much of the globe is not static, but constantly on the move (eg, the
“hydrological cycle” and the great ocean currents). Clean water is constantly supplied to the
Earth by the process of evaporation from the oceans, transport in air currents and precipitation
as rainfall (or snow). The resulting river, lake or groundwater is used by plants and animals,
partially recycles through evaporation, but eventually finds its way back to the ocean with its
burden of leachate from the land or contaminants from our activities. This natural recycling of
fresh water is known as the hydrological cycle. Over geological time, the leaching of salt from
the land has made the sea salty. The main salt in seawater is sodium chloride, which remains
dissolved in the water.
When rainwater runs over rocks rich in calcium or magnesium, it slowly dissolves salts of
these elements to form “hard” water. Hard water shows one or both of two characteristics,
according to the precise make-up of the calcium and magnesium salts. Any calcium or
magnesium salts react with soap to form an insoluble product (as a scum), thus destroying the
effectiveness of the soap. Calcium or magnesium bicarbonate in the water (temporary
hardness) will, on boiling, deposit as a “scale” of calcium or magnesium carbonate which may
affect pipes as well as appearing in domestic kettles. In the ocean, much of the calcium is
converted to hard parts of animals and plants and eventually settles to the sediment layer.
[113.90] Water impurites
The energy from the sun that drives the evaporation of water for rain also powers the great
ocean currents. The ocean near the equator is, of course, hotter and evaporates more quickly
than do the cold waters of polar regions. Conversely, greater precipitation occurs in higher
latitudes. The result is warmer, saltier water near the equator and cold, less salty water near the
poles. The cold water, being denser, sinks to the bottom in convection currents of a global
scale. At the same time, the prevailing wind systems set the oceans in horizontal motion, which
is modified by the Earth’s rotation. The end result is a complex spiral of water between poles
and equator and between surface and bottom. These movements carry our persistent pollutants
to all “corners” of the globe. However, the mixing of the oceans with depth is not so fast as to
dilute contaminants rapidly throughout the oceans’ whole volume.
It is often implied that water that is good enough to drink is good enough for any other use.
However, this is not true. Fish and other organisms, including those at sensitive young stages,
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INTRODUCTION – WATER AND ITS IMPORTANCE IN POLICY AND LAW
[113.100]
are continuously immersed in water. They are much more sensitive to contaminants in water
than are humans who only ingest a limited amount of water and are adapted to deal with
impurities in food. Therefore, water for drinking by humans is not the most sensitive use and
does not require the most stringent water quality standards. In fact, the treatment of water by
chlorination to render it bacterially safe for human consumption may cause it to be toxic to
fish.
Such chlorination can also impart an undesirable taste to the water. This is particularly true of
water with high concentrations of organic matter that can become chlorinated during the
treatment process. These chlorinated organic substances are a concern in relation to human
health. Other problems can also affect the taste and odour of drinking water. For example,
water supplies can suffer from the presence of plant organisms (particularly various species of
algae and the blue-green cyanobacteria). These organisms can impart unpleasant tastes and
odours to the water and they are often not removed by conventional water treatment facilities.
Compounds such as geosmin and methyl iso-borneol, which give the water an earthy, musty
smell, are not removed by filtration, nor are they effectively disguised by chlorination. They
can be removed by granular activated-carbon filtration, but this process is not widely used in
Australia because of its high cost. Powdered activated carbon can be added in water filtration
plants when problems occur, but this is less effective.
As well as the need to protect non-human species by maintaining water quality to a standard
that is better than that of drinking water, there are selfish reasons for such standards. The most
obvious (apart from our dependence on the whole ecosystem) is the problem of
bioaccumulation of contaminants by organisms that are a source of food. This occurs in two
ways: via uptake from water into an aquatic organism, and as biomagnification along the “food
chain”, as animals are sequentially eaten by others.
[113.100] Murcury accumulation
One example is the accumulation of mercury in edible fish. The classic case with respect to
mercury occurred in the Japanese fishing village of Minamata, in the early 1950s, where large
numbers of people became very ill and died unpleasant deaths or produced deformed children.
“Minamata disease” was eventually proved to result from the sea dumping by industry (the
Chisso Corporation) of sludge containing mercury compounds. The mercury became
concentrated in fish, in the form of methylmercury that is a serious toxin, affecting the central
nervous system of human consumers. This resulted in the deaths and illnesses of many
thousands of people. In May 1956, the existence of Minamata disease was recognised and in
1959 a Victims’ Mutual Aid Society sued Chisso for damages. It was only in 1996 that a final
settlement was announced including settlement of claims by victims “unrecognised” by the
government. It is no credit to the combination of science and law that such a case took nearly
40 years to determine. The amount paid out by the industry and government over this issue
exceeded 150 billion yen.
It may be argued that the Japanese system is very different from “Western” legal systems.
However, even now, many alleged sufferers are not officially recognised and it is claimed
(Oshima (1997)) that the overly narrow criteria adopted by the Japanese Government are being
accepted internationally as the standard for methylmercury poisoning, thus affecting potential
judgments worldwide (see also Ishimure (1990)).
This tragedy may seem remote from Australia today. However, the commercial fishery for
shark and related species in Victoria (and elsewhere in Australia) is limited by the mercury
content of the fish, despite the fact that mercury concentrations in the water are very low and
probably of largely natural origin. The problem arises because methylmercury, the toxic form
of mercury in fish, is biomagnified along the food chain, so that species such as swordfish and
sharks, that are at the top of the food chain will contain the highest mercury concentrations.
The commercial catching of species that are known to contain high concentrations of mercury
is prohibited. Of course, mercury discharges are subject to particularly stringent control.
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Another classic case of bioaccumulation is that of organochlorine pesticides, eg, dieldrin and
DDT (dichlorodiphenyltrichloroethane). Like many other organic contaminants, these
compounds have a strong tendency to dissolve in lipids (fat or oil) rather than in water. That is,
they have a high lipid / water partition coefficient. For that reason, they are strongly
accumulated from water into the fatty tissue of animals and may be magnified further between
prey and predator. Walker (1975) quotes an example of DDT accumulation in a Californian
lake, along a simplified food chain, as shown in Table 1.
Bird species have been threatened with extinction because of the effect of these pesticides on
the shell thickness of eggs, causing breakage and failure to reproduce.
Sample
DDT (mg/kg)
Lake water
0.02
Plankton (whole sample)
5
Non-predatory fish (per fat weight)
40–1,000
Predatory fish (per fat weight)
80–2,500
Predatory fish (per flesh weight)
1–200
Predatory birds (per fat weight)
1,600
*
Walker (1975)
[113.110] Explanation of Table 1
It is very clear from Table 1 that very small amounts of certain contaminants in water can
cause dire consequences owing to bioconcentration. However, the degree of bioconcentration
(also referred to as biomagnification) varies between elements or substances. Negligible
bioconcentration may occur for some chemicals even at elevated concentrations. This has
implications for the analyst and legislator. If the environment, including animal species, is to
be protected by checking water quality by direct analysis, then extremely sensitive methods are
necessary, particularly for seawater. On the other hand, advantage can be taken of
bioaccumulation by measuring the contaminants in an “indicator” animal such as shellfish.
This has been done for many years in Australia (Smith and Burns (1978); Fabris, Harris and
Tawfick (1978); Burns and Smith (1981); Hefter (1982)) and internationally in the
much-quoted “mussel watch” program: National Academy of Sciences (1980); Goldberg et al
(1978). This use of indicator organisms, while very useful in scientific surveys, is not used
much in legislation which is traditionally based on direct water quality guidelines.
In Australia and New Zealand, water quality guidelines are documented in the ANZECC/
ARMCANZ Guidelines for Fresh and Marine Water Quality: see ANZECC/ARMCANZ
(2000a). These include recommended guideline trigger values for a range of environmental
values: aquatic ecosystem protection, primary industries (including irrigation and general water
uses, stock drinking water, aquaculture and human consumers of food) and on cultural and
spiritual considerations. The guideline documents also provide interim guidelines for sediment
quality. The revision of the Australian Drinking Water Guidelines produced by the National
Health and Medical Research Council and Natural Resource Management Ministerial Council
was released in 2004 (ADWG (2004)). Australia also has guidelines specific to the disposal of
dredged materials at sea (NAGD, 2009), that were a necessary obligation under the London
Protocol through the Commonwealth Environment Protection (Sea Dumping) Act 1981 (the Sea
Dumping Act).
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INTRODUCTION – WATER AND ITS IMPORTANCE IN POLICY AND LAW
[113.150]
The ANZECC/ARMCANZ guidelines have been adopted by all States. These revised
guidelines involve a risk-based approach to regulation that attempts to move away from single
pass/fail numbers to address issues such as algal blooms, or toxicity, and provide hierarchical
frameworks for assessing the key stressors associated with these issues. If the default guideline
trigger value is exceeded, the frameworks prescribe further investigations that refine the
measurement. For example, in the case of metals in waters, the hierarchy of measurements
might begin with a total metal measurement followed by dissolved metal measurements (after
0.45 µm filtration), followed by a consideration of metal speciation. Site-specific assessments
are recommended, where factors that might modify the effects of a stressor (eg, pH, hardness,
turbidity etc) can be considered. The guideline documents are currently the subject of a further
revision due for completion in 2013.
Environment protection policies, beneficial uses and
water quality criteria
[113.130] Setting guidelines based upon the environmental values or type of use
(ecosystem protection, drinking, swimming etc, as described above) does not of itself define
water quality targets for individual water bodies (apart, that is, from “end of pipe” drinking
water standards). States generally adopt a broad framework for managing environmental water
quality, covering the various uses and geographical extent of water bodies.
For example, in Victoria the fundamental goals for water quality are set out in the State
Environment Protection Policy (SEPP) – Waters of Victoria, with schedules for specific
regions. Other States (eg, Western Australia, New South Wales and South Australia) similarly
have “Environment Protection Policies” or “Protection of the Environment Policies”. Tasmania
has “Sustainable Development Policies”.
For the most sensitive use of the waters, water quality guidelines are then applied to set targets
or limits for water quality, sufficient to protect those uses. While different formal structures are
used in different States, the intention is to set acceptable targets for environmental water
quality according to intended use and geographical area. The licensing of discharges to the
environment must then be consistent with achieving or maintaining these targets.
In addition to policies that are specifically aimed at water quality, there is a trend towards
broad policies aimed at minimising pollution in general, such as waste minimisation and
cleaner production. These are important in improving the environment, though are less directly
relevant to analytical evidence in the legal context.
Licensing
[113.140] One important function of licensing of discharges to water is to limit discharge
to that consistent with the “policy objectives” or “level of protection” for the water body
concerned. This has to take into account the number of existing and potential future discharges,
water quality guidelines, any goal of “non-degradation” where applicable, available
technology, and the concept of mixing zones which are exempted from the water quality goals.
Licences may be based primarily on specified standards (chemical or toxicological), or on
technological and economic grounds such as the “best available technology economically
achievable (BATEA)”, if this provides better quality effluent.
The role of water analysis
[113.150] Water analysis is important at all stages of setting standards, monitoring and
enforcement. Maintaining acceptable water quality depends, among other things, on reliable
water analysis. Monitoring of drinking water quality is obviously important and the
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understanding and protection of natural aquatic ecosystems also depend upon reliable analysis.
All of these analytical aspects can operate within the framework of the law. However, legal
considerations arise most frequently in “environmental” issues rather than in the relatively
well-defined area of drinking water standards.
Water analysis in environmental law
[113.160] Water analysis plays an important part in environmental law. Of course, there
are variations between Acts and from State to State. However, many aspects affecting expert
analytical witnesses are consistent across State and federal legislation. As an example, in the
Environment Protection Act 1970 (Vic), s 39, the definition of water pollution includes the
phrase:
so that the physical, chemical or biological condition of the waters is so changed as to make
or be reasonably expected to make those waters–
(a) noxious or poisonous;
(b) harmful or potentially harmful to the health, welfare, safety or property of human
beings;
(c) poisonous, harmful or potentially harmful to animals, birds, wildlife, fish or other
aquatic life;
(d) poisonous, harmful or potentially harmful to plants or other vegetation; or
(e) detrimental to any beneficial use made of those waters.
Traditionally, water quality guidelines and water analysis have been based on chemical
analysis coupled with knowledge of the effect of chemicals on animals, plants and
communities of both. Owing to the gaps in this knowledge and the gulf between, eg, toxicity
tests on single organisms with single chemicals and the effect on complex communities of
complex mixtures of chemicals, more interest is being taken in direct measurements of the
effect of discharge on organisms. One manifestation of this trend could be greater
incorporation of toxicity tests in water discharge licences. It should also be noted that
conditions placed upon waste dischargers may include not only specific limits on the quantity
of contaminants in a discharge but also requirements to monitor the waste stream and/or the
receiving environment. Because providing incorrect monitoring data may be an offence,
analyses of receiving waters may come under legal scrutiny.
Water analysis is also relevant to civil law, eg, damages arising from toxins in the water supply,
failure to provide water of agreed quality, causing a nuisance etc.
Clearly, the expert witness presenting analytical facts and their interpretations needs to be
aware of the legal definition of the terms he or she is using. For example, in the Victorian law
referred to above, the phrase “so changed” should be noted. In the case of proving pollution of
a river, analysis of the river upstream and downstream of the discharge, as well as of the
discharge itself, clearly cover the aspect of change (up- and downstream) and cause
(discharge). In the case of discharge to a lake or marine environment, the existence of baseline
data (before discharge) and post-discharge data is a valuable back-up to the analysis of the
discharge itself. However, this does not mean that a proven discharge of noxious material will
escape the law if such analyses of receiving water are not available, particularly in light of the
phrase “reasonably expected to”.
The word “pollution” is rather loosely used to mean an undesirable excess of a particular water
contaminant. All pollutants are contaminants, but not all contaminants are pollutants. Some
States have attempted to define pollutant levels, but scientists are in general agreement that this
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INTRODUCTION – WATER AND ITS IMPORTANCE IN POLICY AND LAW
[113.160]
limit cannot be justified scientifically. More appropriate is the use of the concept of “significant
risk of harm” as practised in New South Wales, which implies a risk-based assessment of the
type recommended in the new ANZECC/ARMCANZ guidelines. Apart from proving whether
there is a “risk of harm”, water analysis is vital in prosecutions for breaches of discharge
licence or regulations. Such conditions in licences allowing discharge may set limits on both
concentration and flow rate, or a combination of these expressed as “load”. Such figures may
be set as maximum, mean (arithmetic, geometric or harmonic), median, percentile or some
other statistical values (see glossary for explanation of these terms). Such statistics may also
apply to interpretations of the data for receiving water.
These statistics are often used instead of simple arithmetic means for various reasons,
including prevention of unreasonable bias of results by a single high value. Many natural
systems show a very skewed distribution, often approaching a log-normal distribution, with a
few measurements being much higher than the majority. For example, bacterial samplings from
beaches might occasionally include a fragment of dog faeces that would give an extremely
high E coli reading. This would distort any interpretation based on arithmetic means.
A licence or policy may also specify sampling regime (number and frequency of samples).
However, the following example illustrates a loophole to guard against. If a discharge licence
specified “at least five samples in not more than 42 days”, and the licensee measured 20
samples in this period, there may be no explicit law to prevent the favourable results being
quoted and the unfavourable ones being ignored. However, this would be highly unethical and
contrary to the spirit of the law. In all cases, it is the intention of the law that all valid samples
are taken into consideration.
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SAMPLING AND SAMPLE HANDLING
Sampling
[113.180] Sampling may or may not be undertaken by the same people who conduct the
analysis. As with other material evidence, the “chain of possession” of samples must be
properly documented. Statistical aspects of sampling design are beyond the scope of this
chapter and depend on the context of sampling, eg, proving the fact of contamination or
proving licence exceedence. In many cases, the statistical requirements are embodied in the
appropriate section of the licence or legislation. For example, for a “maximum” concentration
to be exceeded, a single analysis may suffice. Where an average is specified, the number of
samples should be specified also. This is not to be confused with the replication or averaging
that may form part of the analytical procedure.
The primary reference to the details of collection and handling of water samples is the set of
guidelines AS/NZS 5667, published by Standards Australia (1998). More recent details as part
of specific guidance on water quality monitoring and reporting are provided in ANZECC/
ARMCANZ (2000b).
Sample handling
[113.190] As a general rule, the containers and preservatives used should be in accordance
with AS/NZS 5667. However, not every combination of circumstances can be predicted and
some samples may require unusual analysis or special treatment. In such cases, the sample
handling should be consistent with the advice of a competent professional chemist.
Preservation may involve the addition of chemicals or the use of temperature control (eg,
freezing). Depending on the type of analysis to be performed, the samples will have different
“holding periods”, ie, the length of time under specified conditions that the material remains
unaltered and, therefore, fit for analysis. The kinds of changes that can occur include bacterial
degradation, chemical changes and physical loss of the analyte (chemical to be analysed).
Replication in sampling and analysis
[113.200] Replication can be introduced at various stages, from sampling to the final stage
of analysis, to increase confidence in the result. At the sampling stage, it is important that the
samples “represent” the water body being examined. As mentioned in “Sampling” (see above,
[113.180]), this may be spelled out under the regulations or policy. However, many less
well-defined cases will confront the scientist. For example, what is the level of cadmium in a
lake or bay? A single test is of little use and replication with space and/or time is usually
necessary. Appropriate guidance is provided in the monitoring and reporting guidelines: see
ANZECC/ARMCANZ (2000b).
There is potential for a conflict of culture between scientists and lawyers in that the law often
seeks “proof beyond reasonable doubt” (often interpreted as simply “proof”), whereas science
seldom deals in certainties, only in levels of probabilities. It is common practice in many
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aspects of science to quote conclusions based on a stated level of statistical probability. A
common level is the “95% confidence limit”, where there is only a 5% chance of the results
arising by random chance.
The statistical aspect may arise in such questions as: “So the defendant did discharge mercury,
but did he contaminate the whole lake?” Other cases, however, will not require such statistical
treatment and, as with other types of evidence, the court would decide on commonsense
grounds whether a single analysis is convincing evidence.
Replication at the analytical stage depends upon the precision and reliability of the test method
and upon cost considerations. It is often the practice to analyse a single sample in duplicate or
triplicate, quoting a single result for the sample (usually the mean). Part of the laboratory’s
quality control procedure would be to accept or reject results based on the level of agreement
between replicates. The stage at which replication should be introduced depends upon the risk
of error in the various stages from sample treatment to final instrumental reading. Where each
analysis is not replicated, the laboratory should have demonstrated good agreement between
replicates as part of its quality control program.
Detection limits
[113.210] There are many criteria for a “good” analytical method. One of these is the
detection limit. For many analytical methods, a value for the detection limit is derived from the
statistics of repeated analyses of the same sample or of a blank. One fairly rigorous definition
of a detection limit is three standard deviations of the blank plus the absolute value of the
blank: American Chemical Society (1980). This definition is not universally agreed, however.
When the analyst reports on a sample for which the method is insufficiently sensitive to give
an answer (ie, the actual concentration is less than the detection limit of the method) he or she
will usually quote a value “less than detection limit” with the detection limit specified. An
example might be “cadmium concentration <0.1 µg/L” (less than 0.1 micrograms per litre).
In the case of chromatographic methods (see Chromatography, [113.670]), complex mixtures
are separated and the components are analysed, often in the form of peaks on a graph. Here,
detection limits often depend on the amount of interfering compounds in the sample (as well as
in the instrument and reagents). Thus, for example, results for substance “X” in a clean sample
might be “less than 2 mg/L” while results for the same compound in a dirty sample might be
“less than 15 mg/L”. Therefore, care should be taken to ensure that detection limits are valid
for the sample, and not merely based on clean standard solutions.
Many laboratories prefer to provide a “Limit of Reporting” (LOR), rather than a detection
limit, where the LOR represents the reporting limit which the laboratory is very confident in
reaching with their procedures. Frequently the LOR is three to ten times greater than the
detection limit for the method.
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