Abstract
The growing input of many kinds of pollutants, such as pesticide residues and toxic metals, mainly in the estuarine regions, which undergo the impact of agricultural and industrial activities and also of human effluents, has been generating much concern lately, at national and global levels.Estuaries receive the discharge of urban and industrial effluents, which cause the pollution of waters and affect very much the marine life. A rise of the pollutant levels in coastal areas has been observed worldwide and this has lead, in many countries, to various strategies to diminish the impacts caused to the ecosystems. The degree of pollution of the ecosystems can put in danger the health of the populations that use the waters for fishing and leisure activities. Several countries have thus started extensive pollution monitoring programmes, which include analyses of organic and inorganic contaminants in waters ,sediments, marine organisms and others.The main inorganic elements of interest to these kinds of programmes are the ones considered of highest levels of toxicity: mercury, cadmium, lead, arsenic, nickel, copper, zinc, antimony and others.Besides the inorganic elements or compounds, the organic contaminants, such as PCBs (polychlorated biphenyls) and PAHs (aromatic polycyclic hydrocarbons) are of great interest, since they are also very deleterious to biota in coastal and estuarine waters worldwide.The concentrations of potentially toxic substances in marine waters can be extremely low and considerably diversified in space and time, which makes this kind of determination very complex. An alternative approach, which has been in some cases adopted to the determination of toxic substances in marine ecosystems is the biomonitoring by using different species of bivalves. Many elements from seawater and marine sediments can be accumulated by marine invertebrates, such as oysters and mussels. The use of these species as biomonitors allows an estimate of the bioavailability of elements to the biomass in different localities. The mollusks, generally benthonic, can accumulate pollutants without dying.The objective of the present work is to give a contribution to the monitoring of minor and trace elements, such as: As, Ca, Cd, Co, Cr, Fe, Hg, Na, Pb, Se and Zn in some regions of the coast of the state of São Paulo: Cananéia (control), Santos, Bertioga and Caraguatatuba, by means of resident mussels and oysters, by using the methods of neutron activation analysis (AANI) and atomic absorption spectrometry (AAS).The regions that will be studied in the present work have suffered great anthropic impacts, mainly the Baixada Santista region, since, from the 1970´s on, huge amounts of industrial and municipal effluents have been discharged, resulting in contamination of the waters, air and soils. On the other hand, even with the presence of many contaminants, organic and inorganic, the capture of fish, mollusks and crustacea have continued to occur.The data obtained for the possibly contaminated regions will be compared to the ones of clean regions, considered as controls, located in Cananéia and in the Cocanha beach, in Caraguatatuba.Seasonal variations will be studied, for all elements determined, using statistical methods, such as PCA and analysis of variance. It will also be verified if the concentrations of organic contaminats are below the values established by the Brazilian legislation.The experimental part related to the collection of the organisms will be carried out in collaboration with the Oceanographic Institute of USP.
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