Tuesday, October 29, 2019

Environmental Toxicology. Homework 6 Essay Example | Topics and Well Written Essays - 250 words

Environmental Toxicology. Homework 6 - Essay Example 36 Bioassessibility refers to the amount of a pollutant that can be dissolved by the digestive fluids. Lead enters the body through either ingestion or inhalation. As much as it can be eliminated, continuous exposure leads to accumulation as well as intoxication. Analysis of waste materials indicates that 40% of lead was present as cerrussite (Brack, 2011). Cerrussite is a highly bio accessible lead-carrying molecule. However, 65% of lead also exists in the waste in a bio accessible form (Brack, 2011). This shows that lead which does not exist as cerrussite is also high bio accessible. Lead bearing minerals such as sulfur and oxygen make it more bio accessible. Presence of these stable minerals is evident in the stomach and the intestinal phase. The higher the residence of the lead in the gut the higher the bio accessibility. 13. Briefly describe the chemical and biological processes by which mercury from a coal-fired power plant enters a lake and makes it way to humans through fish caught and consumed by a fisherman or fisherwoman. Coal fired power plants emit mercury, which accumulates as sediments. Sulfur reducing bacteria then converts the mercury into methyl mercury. The sediments are then passed into water bodies and into the systems of fishes. Mercury is bio accumulative and hence it is retained in the bodies of the fish. There is a high bio concentration of methyl mercury in these aquatic organisms (Brack, 2011). Fishermen catch the fish and as they consume them, methyl mercury is passed on to

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