Heavy Metal Toxicity Testing in Environmental Samples

摘要: The toxicity of heavy metals in the environment depends on a number physicochemical and biological factors. complexity these relationships has encouraged use bioassays for direct measurement [table: see text] impact toxic selected test species. Fish daphnid are well accepted by scientific regulatory communities, but their length (48 h or more) considerable time effort needed to culture organisms make application sample screening problematical. Microbial biochemical assays based inhibition bioluminescence, enzyme activity, biosynthesis, growth, respiration, heat production typically faster less expensive than traditional fish bioassays. Some tests approach equal sensitivity daphnids metals. Since soil acts as sink airborne waste-applied metals, uptake plants associated impacts important. Growth inhibition, induction, stress proteins have been considered end points. Enzymatic developed that specific metal toxicity. Such can facilitate reduction evaluations. Detection individual may eventually be possible using biosensors consisting genetically engineered microorganisms. Direct solid-phase soil, sediment, sludge toxicity, bacterial bioluminescence activity points, developed. complement nematodes earthworms indicator organisms. Based work reviewed, we draw following conclusions: 1. Microtox assay is sensitive mercury would fail detect certain such cadmium. Among all microbial bioassay growth alga Selenastrum capricornutum appears give lowest EC50s, similar those seen 2. Biosensors, microorganisms, offer an elegant means detecting presence environmental samples. However, at present time, they not designed assessing 3. useful directly bioavailability toxicants samples, thus avoiding need fractionation.+4