Detection of pollutants in marine organisms and in the environment as markers of environmental quality

Abstract

This chapter presents an overview of various techniques of detection of different types of pollutants such as organochlorine pesticides (e.g. DDT, HCHs, aldrin, dieldrin, endrin, Hepox, heptaclor), polychlorinated biphenyls (PCBs), trace metals and heavy metals etc. in different compartments (water, sediment and biota) of the marine environment. Among the various techniques of measurement of the concentration of pollutants in the marine environment it has highlighted the recent advancements of analysis of chlorinated hydrocarbons using gas chromatography coupled with electron capture detector. The biogeochemistry of trace elements in the oceans is controlled by the competing processes of particle scavenging, uptake and releases by marine microorganisms and is regulated by chemical speciation. The chemical speciation controls the geochemistry of these elements and their availability to microorganisms. For these reasons, chemical speciation is of great significance to understand the chemical processes in the oceans. Electroanalytical methods are very useful to evaluate these processes and to determine trace elements and their chemical speciation in natural waters. In this regard, cathodic stripping voltammetry (CSV) and chronopotentiometry are very much significant to determine trace elements and their chemical speciation in seawater. Apart from these elements CSV technique has also been developed to determine several organic compounds including purines, folic acid, sulfur containing amino acids and various thiol compounds (cysteine and glutathione) in seawater. Heavy metal concentrations in the aquatic environment can be determined by the modern technique of flame or graphite furnace atomic absorption spectrophotometry The impact of pollutants on the marine organisms can be measured in terms of the biological responses of the organisms exposed to different types of pollutants. The biomarkers which are found to receive special attention are : metallothionein induction, acetylcholinesterase inhibition, cytochrome P450 system induction, imposex, lysosomal enlargement and lysosomal membrane destabilization, peroxisome proliferation and DNA integrity. These biomarkers are of great significance to evaluate exposure to and the effects of different contaminants (metals, organic xenobiotics and organometallic compounds) and they can be measured using different methodological approaches (biochemistry, cytochemistry, and immunochemical methods based on the use of biotechnology. Marine bivalve mollusks such as mussels are appropriate sentinel species for most of the biomarkers proposed except for the induction of the cytochrome P450 system, which should be measured in fish and the degree of imposex which is known as a biomarker of exposure to TBT specifically measured in certain gastropod mollusks. Genotoxic agent can affect the integrity of DNA. Thus, DNA damage (strand breaks) has been proposed as a useful parameter for assessing the genotoxic properties of environmental contaminants. The level of double strandedness with respect to total DNA determined the effect of various genotoxic chemicals on the integrity of DNA