Abstract
Nowadays, organisms are increasingly being used in biomonitoring to assess bioavailability and bioaccumulation of contaminants. This approach can use both native and transplanted organisms in order to accomplish this task. In Brazil, most of the studies related to bioaccumulation of contaminants in oysters deal with metals. The present work employs this kind of test in Brazilian coastal estuaries (Santos and Paranaguá) to evaluate total mercury and polycyclic aromatic hydrocarbon contamination in sediments and oysters (native and caged Crassostrea rhizophorae). The methodologies employed were based on known USEPA methods. Results have shown a significant contamination in Santos sediments and consequent bioavailability of organisms. Paranaguá sediments presented lower contamination in sediments, but native oysters were able to accumulate total Hg. The experiments done with caged oysters did not show significant bioaccumulation of Hg and PAHs in the Paranaguá site, but proved to be an excellent tool to assess bioavailability in the Santos estuary since they were able to bioaccumulate up to 1,600% of total PAH in the samples from the inner part of this estuary when compared to control organisms. Multivariate statistical analyses employed to these results have separated the sites evaluated and the most contaminated samples from the least contaminated.
Highlights
Some organic and inorganic chemical contaminants have the capacity of persisting in the environment, bioaccumulate in tissues, and are toxic to organisms
The main classes of elements and compounds that belong to this category are some metals such as mercury, cadmium, and lead as well as those denominated POPs such as pesticides, dioxins, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) [1, 2]
Native oysters (Crassostrea rhizophorae) (Guilding, 1828) (Bivalvia: Ostreidae) were collected where possible, and one cage containing about 30 oysters from the same species was placed at each point for bioaccumulation assessment
Summary
Some organic and inorganic chemical contaminants have the capacity of persisting in the environment, bioaccumulate in tissues, and are toxic to organisms. The contaminants interact with sediments, water column, and organisms; such interactions are controlled by several physical and chemical processes, and the final result may be the chemical release, immobilization, or their transformation into more reactive forms or subproducts, which are more effectively available to organisms [3]. Bioaccumulation is the process by which a chemical is absorbed by an organism exposed to it. It is a net result of competing processes of absorption, ingestion, digestion, and excretion [5] and involves the endogenous processes of biological depuration. Bioaccumulation studies can be interpreted in human health risk analysis when the target
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