Trophic transfer of methylmercury and trace elements by tropical estuarine seston and plankton

摘要: Methylmercury (MeHg) and trace elements (TE), mercury, selenium, cadmium, lead copper, were determined in a microbial loop composed by three size classes of autotrophic heterotrophic microorganism samples, 1.2-70 μm (seston, SPM), 70―290 (microplankton) ≥290 (mesoplankton) from five sampling stations within polluted eutrophic estuary the Brazilian Southeast coast one external point under influence bay. TE concentrations range reported for marine microorganisms uncontaminated locations. Microplankton was primarily proto-zooplankton diatoms (>90%) while approximately 50% mesoplankton mainly ofcopepods. MeHg samples did not differ among Cd, Pb Cu seston higher sampled inside Guanabara Bay (0.67 μg Cd g ―1 , 9.26 8.03 ) than (0.17 3.98 2.09 ). Hg, Se points more waters station. The trophic transfer observed between levels prey (seston microplankton) to predator (mesoplankton). successive amplification ratios Hg with increasing (43%), microplankton (59%) (77%) indicate that biomagnification may be occurring along food web. Selenium, is efficiently accumulated organisms through transference, biomagnified web, Pb, present same behavior. Concentrations differed classes, indicating accumulation size-dependent. related taxonomic groups' composition planktonic microorganisms. Results suggest importance role level regulating element transfers. Eutrophication dilution provide process-oriented explanation lower collected at