Determining safe contaminant concentrations
Inadequate guidelines, tools and frameworks for water and sediment quality assessment impede decision-making processes, increasing the costs to both industries and regulators.
The Australian New Zealand Guidelines for Fresh and Marine Water Quality are undergoing revision, with CSIRO addressing contaminants in waters and sediments.
The guidelines are produced as part of the Australian National Water Quality Management Strategy (NWQMS) which advises on sustainable use of water resources in Australia and New Zealand. They are designed to help stakeholders assess water quality and make decisions about its use.
Many of the existing water quality guideline values are of low reliability due to limited toxicity data, but in the 15 years since the 2000 Guidelines were released, there have been significant research advances in this area.
The challenge is to incorporate new findings from water and sediment assessments into the protocol to ensure more reliability of guideline values and the application.
This will allow environmental managers to better assess the risks posed by aquatic contaminants, target management to areas of greatest ecological risk, and save unnecessary expenditure where guidelines were previously unreliable.
Revised protocols and new guidelines
We have been working with other national experts to produce two written protocols for deriving water guideline values for contaminants. The publications are:
- Revised Method for Deriving Australian and New Zealand Water Quality Guideline Values for Toxicants
- Technical Rationale for Changes to the Method for Deriving Australian and New Zealand Water Quality Guideline Values for Toxicants
New guideline derivations use these latest protocols and new toxicity data for a number of contaminants. Having more toxicity data, better considerations of data quality and improved derivation protocols will make the new guidelines more valuable.
They will be added to a suite of new, more reliable guideline values for contaminants prioritised by environmental agencies that are being developed under contract for the Commonwealth Department of Agriculture and Water Resources.
CSIRO has also produced comprehensive documentation on the revision of sediment quality guidelines (Revision of the ANZECC/ARMCANZ Sediment Quality Guidelines) that recommend the use of multiple lines of evidence (from chemistry, toxicity, bioaccumulation and ecology) in a weight of evidence assessment process where guideline values are exceeded. This has been peer reviewed and subjected to public comment so is ready for adoption.
CSIRO's book, Sediment Quality Assessment; A Practical Guide is also available.
Improved approaches benefit industry and the environment
Quality science can make a big difference to the effectiveness and efficiency of environmental regulation.
For example, the current low reliability guideline value for aluminium in marine waters is frequently exceeded naturally in coastal waters, causing public concern. Following the new protocols, we undertook careful toxicity testing leading to a high reliability value that was almost 50 times higher than the previous guideline value, while still being protective of the health of aquatic organisms.
Many industries can now safely discharge waters that were previously deemed to be too hazardous to discharge. In undertaking these studies, mechanisms of toxicity are now better understood and are being adopted in later derivations.