The Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agriculture and Resource Management Council of
Australia and New Zealand (ARMCANZ) have announced that the 1997
review of the Australian Water Quality Guidelines will include for the first time,
consideration of sediment quality guidelines. For this reason, it is timely to
review the methods for establishing such guidelines, and the manner in which
they could be used in managing the quality of sediments in Australian rivers,
lakes and drainage systems.
In this thesis, the problem of the development of sediment quality guidelines is
introduced and basic questions relating to the development of such guidelines
are addressed. The importance of sediment monitoring and sediment quality
assessment in aquatic ecosystem management is demonstrated, and the role of
sediment quality guidelines in the process of sediment quality assessment is
discussed. The arguments considered in this thesis are illustrated by specific
reference to the setting and use of sediment quality guidelines for heavy metal
contamination.
A number of physico-chemical factors (grain size distribution, pH, redox
potential, alkalinity and hardness, salinity, organic matter) can affect the
bioavailability and toxicity of contaminants in sediments, and these factors may
vary spatially and temporally within and between sediment deposits. Changes
in physico-chemical conditions as a result of natural or anthropogenic
processes may lead to major changes in bioavailability of sediment
contaminants. The variability of these physico-chemical factors has
ramifications for the way in which sediment quality guidelines are derived and
used.
Factors affecting the way in which toxicity is measured (test species chosen,
toxicological end-point measured, duration of test relative to life-cycle), and
toxicity data is interpreted, are also important to the development of useful
sediment quality guidelines. All of these factors must be taken into account in
deriving sediment quality guidelines for Australian conditions.
The large number of factors affecting the sensitivity and efficiency of sediment
quality guidelines means that a simple set of numerical guidelines, as has been
used in the past, is not appropriate. A multi-step assessment procedure will be
required.
Methods of setting sediment quality guidelines that have been used by
authorities in overseas jurisdictions were reviewed. Advantages and
disadvantages of the various methods were compared. None of the methods
used overseas has been shown to be applicable to Australian conditions. In the
absence of a suitable method for deriving Australian sediment quality guidelines
in the short term, the adoption of the Canadian Interim Sediment Quality
Guidelines as interim sediment quality guidelines for Australia is recommended.
Sediment quality guidelines need to be viewed in the context of the overall
environmental management process, of which they form an integral part. The
policy background to environmental management in Australia, and the
management frameworks that have been put in place to implement the policy,
are outlined. The AS/NZS/ISO 14000 series of standards for environmental
management systems provides a framework which is consistent with the
principles and objectives of environmental management in Australia. It
therefore provides an appropriate framework within which to develop and use
sediment quality guidelines.
Within the broad AS/NZS/ISO 14000 policy, a framework for the
development and use of sediment quality guidelines is proposed, which will
provide a technically and legally defensible basis for the management of aquatic
sediments in Australia, in the short term and long term. The proposed
framework involves the setting of Interim Sediment Quality Guidelines for
Australia, based on the best scientific knowledge currently available. The
framework recognises that the factors affecting the bioavailability and toxicity
of sediment contaminants are complex, and that the current level of knowledge
of sediment processes is incomplete. Therefore, a conservative approach to
setting guidelines is taken, and a highly sensitive guideline based on that used in
Canada, is proposed. The framework further recognises that this approach will
lead to over protection of the environment in some cases, so a "Decision
Tree" approach is taken. The "decision tree" allows the consideration of more
complex interactions than can be incorporated into simple numeric guidelines,
while attempting to simplify the assessment process. In keeping with the ISO
14000 series of standards for environmental management, the framework also
explicitly includes steps designed to ensure that monitoring data are regularly
collated, and analysed, and where necessary, guidelines are able to be updated
in light of new knowledge gleaned from the review process.
The proposed framework is appropriate to, and supportive of, the principles of
environmental management as set out in Australian Government policy
documents, inter governmental and international agreements, and legislation.
It provides a basis for the on-going collection of data suited to increasing our
understanding of the factors influencing the behaviour of contaminants in
sediments, and thereby lead to continual improvement in sediment quality
guidelines for use in Australian conditions.
| Identifer | oai:union.ndltd.org:ADTP/218805 |
| Date | January 1997 |
| Creators | Buckley, David, n/a |
| Publisher | University of Canberra. Resource, Environmental & Heritage Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright David Buckley |
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