ENVIRONMENTAL MANAGEMENT: Algae recruited for waterways clean-up

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Most people have heard about the canary in the cage; the hapless sentinel that warns miners of lethal build-ups of poisonous gas by falling off its perch, dead. Researchers have applied a similar principle to their development of a procedure for identifying and removing toxicants from estuarine and coastal waters, using highly sensitive algae as toxicity test subjects.

The use of such ‘lower order’ organisms provides a sensitive measure for toxic contamination that eventually impacts on life further up the food chain. This use of algal sentinels is at the heart of an ecotoxicology procedure called Toxicity Identification and Evaluation (TIE) that CSIRO scientists have developed for the clean-up of environmentally sensitive waterways. The early success of the concept has resulted in further development being funded by some of the world’s biggest mining companies.

One of the problems in eliminating toxicants from effluent that ends up in waterways is that it typically comprises a cocktail of chemicals, and attempting to chemically measure every individual contaminant is expensive, lengthy and tells us little about potential impact.

What the innovative TIE procedure does is reveal the class or related group of chemical compounds causing the damage, and the overall level of toxicity.

Scientists at the Centre for Environmental Contaminants Research (www.clw.csiro.au/cecr/), in collaboration with the NSW Department of Environment and Conservation’s Centre for Ecotoxicology, developed TIE by adapting existing procedures for separating chemicals and complementing this with their groundbreaking use of algae as toxicity test subjects.

One early successful application of TIE revealed that the source of toxicity in offshore discharge from Melbourne Water’s Eastern Treatment Plant for sewerage was ammonia. This enabled the authority to engineer an effective removal. Melbourne Water’s project manager in Marine and Treatment Technology Research, David Gregory, says TIE has quickly become a very useful tool for identifying classes of toxic compounds in effluents: “Knowing the general chemical properties of these substances helps us identify their source and origins, and provide treatment to remove them or prevent them getting into discharge in the first place.”

The leader of CSIRO’s ecotoxicology team, Dr Jenny Stauber, says the TIE technique has also been used by the NSW and Victorian Environment Protection Authorities, Sydney Olympic Park Authority and the Port Kembla and Townsville Port Authorities.

Although there was no external funding to develop TIE for water contaminants, Rio Tinto, BHP Billiton and Xstrata are now providing $300,000 over three years for research into adapting TIE for use in sediment analysis.

The director of CSIRO’s Centre for Environmental Contaminants Research, Dr Graeme Batley, says the TIE procedure can provide a more comprehensive ecological health report than, for example, the US Environmental Protection Agency’s procedure, which only targets higher order organisms like fish.

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