Volume 7 Number 2 - July 2001

95-108: THE REVISED AUSTRALIAN AND NEW ZEALAND WATER QUALITY GUIDELINES FOR TOXICANTS: APPROACH TO THEIR DERIVATION AND APPLICATION
John Chapman
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Abstract: The revised Australian and New Zealand water quality guidelines for toxicants present chemical-specific guideline figures for around 200 organic and inorganic (metallic and non-metallic) toxicants covering freshwater and marine systems. These figures are termed “trigger values” because it is intended that, if they are exceeded, further investigations will be triggered. Toxicant guideline trigger values have been derived primarily according to risk assessment principles and recommendations for their use follow a hierarchical decision framework that is also risk-based. This paper discusses the approach and philosophy behind derivation of the revised guideline trigger values, which are estimates of the highest concentration of chemicals that are expected to have no adverse effect. It is intended that, wherever possible, the figures should be applied at specific sites according to a risk-based decision scheme, taking into account the interaction of natural water quality and other parameters with toxic chemicals at the specific site. Such site-specific assessment is therefore an integral part of these guidelines and the detailed decision scheme is intended to assist a catchment manager to arrive at a final guideline value appropriate to the location being studied. A range of approaches may be used to address these interactions depending on the specific issues at hand and the availability of data. The decision-tree framework described in this paper provides catchment managers with practical guidance on how to apply the trigger values to specific sites according to local environmental conditions and also helps to focus future research needs. Key words: water quality guidelines, toxicants, derivation, site-specific.

109-122: INCORPORATING METAL SPECIATION AND BIOAVAILABILITY INTO WATER QUALITY GUIDELINES FOR PROTECTING AQUATIC ECOSYSTEMS
Scott J Markich, Paul L Brown, Graeme E Batley, Simon C Apte and Jennifer L Stauber
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Abstract: Guidelines for metals in aquatic ecosystems are typically based on total concentrations. However, it is well established that metal bioavailability (ie. the ability of a metal to bind or traverse the cell membrane) is critically dependent on the physicochemical form, or speciation, of a metal. As such, guidelines based on total concentrations may be overprotective, since only a fraction of the total concentration may be bioavailable. Following a risk-based approach, a decision tree was developed to account for metal speciation and bioavailability in aquatic ecosystems. The decision tree includes three increasingly complex levels of analysis: (i) total acid-soluble (unfiltered) metal concentration; (ii) dissolved (filtered) acid-soluble metal concentration, and (iii) the concentration of specific metal species (eg. geochemical modelling) or groups of metal species (eg. chemical measurement) and/or biological testing. The complexity of analysis for a water sample depends on guideline conformity at each level of the decision tree. As part of this approach, algorithms for hardness-dependency were derived for Cd, Cr(III), Cu, Pb, Ni and Zn in freshwaters (= 2.5‰ salinity), because of its established effect on the bioavailability of these metals. The measurement of metal speciation and bioavailability permits guidelines for protecting aquatic ecosystems to be potentially relaxed on a site-specific basis. This signifies a move to develop chemical indicators further so that they better reflect biological effects. Key words: metal speciation, water quality guidelines, aquatic ecosystems, hardness, geochemical modelling.

123-136: DERIVATION OF THE AUSTRALIAN AND NEW ZEALAND WATER QUALITY GUIDELINES FOR TOXICANTS
Michael St. J. Warne
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Abstract: A new framework was developed and used to derive the Australian and New Zealand (ANZECC & ARMCANZ 2000) water quality guidelines for metal, inorganic and organic toxicants. This framework incorporates the principles of risk and recent advances in ecotoxicity modelling. As such, it is a significant advance on the previous ANZECC (1992) and other international water quality guidelines. Two different methods were used to derive the guidelines: a modification of the Canadian (CCME 1991) assessment factor method, and a new statistical distribution method called the Burr Type III method (Campbell et al. 2000) which was developed from the Aldenberg and Slob (1993) method. This paper provides the rules governing the framework, details of the collation and screening of the toxicity data and the methods used to derive the guidelines. Key words: toxicants, trigger values, statistical distribution, assessment factor.

137-156: DERIVATION OF WATER QUALITY GUIDELINE VALUES FOR HEAVY METALS USING A RISK-BASED METHODOLOGY: AN APPROACH FOR NEW ZEALAND
Christopher W Hickey and Eric Pyle
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Abstract: The Australian and New Zealand Environment and Conservation Council (ANZECC) has undertaken a revision of the water quality guidelines for Australia (ANZECC 1992). The revised ANZECC guidelines adopt a statistical approach, which the Ministry for the Environment had proposed for New Zealand before the ANZECC review commenced. In this paper we present the results of the application of the risk-based methodology to guideline calculations for a selected range of priority metals, and discuss their application in relation to the narrative guidelines in the New Zealand Resource Management Act 1991. Guidelines were calculated for freshwater and marine species using chronic (long-term) effects data and 99% level of protection with 50% confidence and 95% level of protection with 50% confidence. The use of the 99% protection guideline values is recommended for waters to be protected from ‘adverse effects'. For receiving waters requiring protection from ‘significant adverse effects', the statistical approach can be used to vary the level of protection according to the values to be protected. In most cases the 95% protection guideline values are recommended, but in certain circumstances the 90% could be used. All of these guideline values would be implemented on a soluble (ie. < 0.45 µm) metals basis. A number of limitations to the available datasets were identified, including: (i) minimal data available for some contaminants (eg. CrIII and As) which are of concern in the New Zealand environment because of their widespread use in timber treatment; (ii) the datasets used for guideline derivation included very few Australian or New Zealand studies with native species. This largely results from the use of chronic data, whereas the majority of Australasian studies are of acute exposures; (iii) the need to include a range of endpoints (other than the recommended ‘no observed effect concentration' (NOEC)) in order to increase the number of species represented; and (iv) the datasets were generally identified as being under-represented in freshwater aquatic insects and marine fish species. We recommend that environmental monitoring data from carefully designed programmes be fed back into the criteria assessment programmes to evaluate the applicability of the guidelines used. Key words: New Zealand , toxicants, metals, freshwater, marine, water quality guidelines.

157-174: CONSIDERATIONS WHEN APPLYING THE REVISED TOXICANT GUIDELINES
John C Chapman, Michael StJ Warne and Ron WR Patra
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Abstract: The risk-based decision scheme devised for deriving site-specific water quality guidelines allows the national trigger values for toxicants to be adjusted to take into account the characteristics of the particular site under study. The scheme provides the opportunity to apply the guidelines in a more realistic manner to take into account the variety of factors that can potentially modify the toxicity of a chemical. It enhances confidence in the use of guidelines at particular sites. It is usually not necessary to proceed through each step in turn at each site, as the approach can be tailored to deal with the significant issues and water quality parameters at that site. For many chemicals, apart from metals, there are limited quantitative data available to enable users to make better estimates of bioavailable concentrations or to adjust trigger values to account for the water quality conditions at the study site. Where only general trends are available, users can only make estimates of increased or decreased risk under the specific conditions. This paper provides some examples, where data are available, of these quantitative relationships for specific chemicals. When data sets were robust, such as for pentachlorophenol, simple overall quantitative adjustments for factors that affect toxicity (in this case, pH) gave as good estimates of changes in the guideline values as more complex manipulations of each data point, followed by recalculation of the guideline value. Background information is given that may assist with qualitative estimates of risk, and other approaches to the decision scheme are discussed, including use of a weight-of-evidence approach to deal with different types of site-specific direct toxicity assessment data. These can assist users of the guidelines to apply the decision scheme as effectively as currently possible, and to focus future research to fill gaps in knowledge. Key words: Water quality guidelines; application; decision scheme.

175-198: DIRECT TOXICITY ASSESSMENT (DTA) FOR WATER QUALITY GUIDELINES IN AUSTRALIA AND NEW ZEALAND
R A van Dam and J C Chapman
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Abstract: Direct toxicity assessment (DTA) involves the assessment of the adverse impacts of complex mixtures of compounds, ranging from concentrated industrial effluents to natural waters, on aquatic organisms. The major benefit of DTA is that it can assess the toxicity of waters, in which the number of unidentified components may number thousands, and their behaviour, or interactions cannot be predicted. Thus, DTA enables a greater understanding of potential impacts to aquatic environments, which in turn aids in the development of environmental protection measures. The Australian and New Zealand Guidelines for Fresh and Marine Water Quality has recently undergone a major revision, particularly in its philosophical approach. The emphasis is on deriving water quality guideline values that more accurately reflect the particular ecosystem being considered. Thus, site-specific issues and characteristics are of major importance. As such, DTA has been recommended as one of the tools available for developing more relevant guideline values, and for establishing whether aquatic ecosystems are being adequately protected. This paper discusses a number of important aspects of DTA, including its advantages and limitations, its potential applications and the recommended use of DTA in the revised Water Quality Guidelines. The current status of DTA in Australia and New Zealand is briefly reviewed, and three case studies highlighting the benefits of the approach are presented. Guidance and considerations for the development of DTA test methods are detailed in order to provide managers with an increased awareness of the requirements. Finally, recommendations for carrying out DTA for the purposes recommended in the revised Water Quality Guidelines are presented. Key words: direct toxicity assessment, whole effluent toxicity testing, water quality guidelines, Australia , New Zealand .

199-208: GUIDELINES FOR WATER QUALITY MONITORING AND REPORTING
Barmuta LA, Maher WA and Batley GE
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Abstract: The Australian Guidelines for Water Quality Monitoring and Reporting (ANZECC & ARMCANZ 2001b) is one of the series of documents that form part of the National Water Quality Management Strategy. It is complementary to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ 2001a) and provides much of the generic, background advice necessary to plan and carry out a program of monitoring water quality. Emphasis is placed on clearly articulating the objectives of a program after a conceptual model of the key processes has been articulated by the monitoring team. This process will identify a number of candidate variables for potential monitoring which will include a range of physical, chemical, ecotoxicological and biological variables. The use of professional statistical expertise is then strongly encouraged when planning the study design of the program, which should clearly articulate the spatial and temporal features than need to be captured in sampling. Generic considerations of field sampling and laboratory analysis are covered, with extensive cross-references to protocols in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality and elsewhere. A variety of descriptive and inferential statistical procedures can be used to explore and analyse the data, and, again, professional statistical advice is essential to ensure that methods are being chosen and used correctly. The method for using the trigger value procedure recommended by the Australian and New Zealand Guidelines for Fresh and Marine Water Quality for physical and chemical values is described in some detail. Finally, advice is provided about the reporting and dissemination of results to a variety of likely stakeholders in the outcomes of a water quality monitoring program. Key words: water quality, monitoring, impact assessment, trigger value.