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Distribution behavior and toxicity of metals and sulfur in pore water surface sediments of the gulf of saco Cariaco, estado sucre, Venezuela

Abstract:

Because the criterion of sediment quality, derived from the partition equilibrium model, argues that the pore water is a major source of accumulation and toxicity of chemicalspecies in the tissues of benthic organisms, and trying to reproduce the diffusion processes in them, it was considered interesting to study the behavior of metals and sulfur in the pore water of surface sediments of saco Gulf of Cariaco and its absorption into polyacrylamide hydrogels, crosslinked with N,N metilenbisacrylamide. Total concentrations in pore water (μg/L, except S in mg/L) measured by ICP were: Al (173- 530), Cd (<LD-206),Cu (102-387), Cr (139-210), Fe (152-1299), Mn (33-362), Ni (93-266), Pb (66-238), Zn (90-258) and S (584-975). The xerogel, previously impregnated with pore water, were analyzed by EDX- SEM and did not show the presence of toxic metals, except for two sampling locations. The test of survival of Artemia sp. and the hemolytic activity were negative. Principal component analysis associated Ni, Cd, Pb, Cu, Zn, Mn and S to the first component (60%), whereas the second was (24%) positively associated to Fe and Al, and to Cr negatively. These results suggest a mechanical bonding between Mn and Ni, Cu, Pb, Cd and Zn, and their simultaneous remineralization. The total concentrations found in this study were exceeded only in one sampling site when compared to the results reported by Man et al. (2004), in the coastal wetland Mai Po (China). Most metals were unable to diffuse through gel, probably due to formation of colloids or linkage to dissolved organic matter. The results indicated that the sediments are not toxic and are medium to high quality.