Influence of Ecological and Biological Parameters on the Accumulation of Methylmercury and Trace Elements (Hg, As, Ag, Cd, Cu, Pb, Se) by the Liver of Dolphins from the Western South Atlantic Ocean
Cetaceans are very sensitive to environmental changes and have been considered good bioindicators of environmental contamination. In this study, the analysis of tissues of dolphins was used as a tool for the assessment of marine pollution by trace elements in the Western South Atlantic Ocean. The present work tested whether ecological and biological parameters have an influence on the accumulation of trace elements (As, Cd, Cu, Pb, Se, Ag, Hg) and methylmercury (MeHg) by the liver of three cetaceans species: two species of coastal habit (Pontoporia blainvillei, Sotalia guianensis) and one of oceanic habit (Stenella frontalis), that were incidentally caught in fishing nets in the Southeastern Brazilian coast. Hg concentrations were determined by FI-CV-AAS, using sodium borohydride as a reducing agent. MeHg analysis was made by digesting samples with an alcoholic potassium hydroxide solution followed by dithizonetoluene extraction, and then was identified and quantified in the toluene layer by a CG-ECD. The other trace elements were determined by GF-AAS with PIN platforms. Pd nitrate was used as chemical modifier in all determinations by GF-AAS, except for Cu. MeHg and trace elements concentrations found in liver were of the same order of magnitude as those reported in earlier studies with the same dolphin species from Brazil and Argentina. Inter-species differences were observed on the accumulation of MeHg, Cd and Pb. However, the three cetacean species presented similar hepatic concentrations of As, Cu and Ag. The highest concentrations of these elements were observed in the liver of the oceanic cetacean species. No gender differences were found on the bioaccumulation of trace elements and MeHg. Biological parameters such as, population, body length and sexual maturity influenced on the MeHg and trace element accumulations by liver, according to the cetacean species. S. guianensis, which co-habits the same coastal marine environment that P. blainvillei species, presented a significant difference between hepatic MeHg, Hg and Se concentrations. An inverse and significant linear relationship was found between Hg concentration and the hepatic ratios of MeHg to Hg. A significant positive linear relationship was observed between the molar concentrations of Hg and Se in the liver of each dolphin species. S. guianensis was the only dolphin species that presented a Se:Hg molar ratio close to 1:1, showing that a probable detoxification process can be occurring in its liver. P. blainvillei and S. frontalis presented Se:Hg molar ratios close to 4:1 and 2:1, respectively. Differences found among the concentrations in dolphins were probably due to the preferred prey, bioavailability of elements in each marine environment, and environment variables (water temperature, net primary production). As a consequence, concentrations of trace elements in the tissues of these dolphin species can be considered to be a result of the surrounding environment.
bioaccumulation Brazilian coast ecological and biological parameters liver of marine dolphin species methylmercury trace elements
HA KEHRIG TG SEIXAS O MALM I MOREIRA
Instituto de Biofísica Carlos Chagas Filho,Universidade Federal do Rio de Janeiro,21941-902,Brazil Departamento de Química,Pontifícia Universidade Católica do Rio de Janeiro,22453-900,Brazil
国际会议
2009 International Symposium on Environmental Science and Technology(2009环境科学与技术国际会议)
上海
英文
994-999
2009-06-02（万方平台首次上网日期，不代表论文的发表时间）