Sediment toxicity testing: battery test evaluation of shallow urban streams and the effect of sampling method on toxicity

• Main Author: Smith, Jacqueline A.
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/5519

Sediments have been recognized as a potential source of contamination in aquatic environments. Toxicity testing has been used as a tool for studying sediment related toxicity, although many aspects of the methodology are still evolving. However, it has been debated whether or not the results of laboratory assays can be extrapolated to ecosystems effects. As well, questions arise about changes that occur in sediments when they are manipulated in the laboratory during toxicity testing. This study examined the effects of sampling method on sediment toxicity. Toxicity tests were performed on sediment which had been mixed (homogenized) and the toxicity compared to that of undisturbed sediment cores, where the integrity of the sediment had been maintained. Toxicity tests performed on the sediment included Daphnia magna, Chironomus tentans, and Microtox®. Chemical analysis of the sediment was also done, including metals, polynuclear aromatic hydrocarbons (PAH), ammonia, and metal/sulfide ratios. It was found that the method of sampling affected toxicity of sediments to Chironomus tentans in about half the cases. However, the method of sampling did not affect toxicity to Daphnia magna, probably because the type of contaminants found in the sediments were not available to the Daphnia. Daphnia magna were unresponsive to all sediment tested. A bacterial luminescence bioassay (Microtox®) was also performed to compare the sensitivities of the different toxicity tests. It was found that the Microtox® Solid Phase Test was the most sensitive of all the tests, and was able to distinguish between contaminated and uncontaminated sediment. The measurement of metal/AVS ratio in sediment was not found to be a useful tool in determining whether a sediment would be toxic or non-toxic to organisms.