An evaluation of clam Amiantis umbonella (bivalve) as a bio-indicator of heavy metal pollution in Kuwait marine coastal waters.

摘要

To evaluate the clam Amiantis umbonella as a bio-indicator of metal contamination, the concentrations of a number of metals (Hg, Cd, Pb, Cu, Ni, Mn, Cr, V, Zn, and Fe) were determined in clam's soft tissues, in different organs, water, and sediment in Kuwait Bay of the Arabian Gulf. The primary objective of this study was to evaluate the relationship of all metals concentrations in soft tissue and various organs of clam, water and sediment and to compare them with a reference site, and with results obtained from other geographical areas of the world. Metal concentrations and metal burdens of Pb, Hg, Cu, and Cd in the soft tissues of clam were also compared as a function of clam size.;Hg, Cd, Cu, Ni, Cr, V and Pb were significantly higher in water and sediment near point sources compared to reference sites. The concentration of all metals, except Zn were significantly higher in kidneys, gonads, mantles, gills, livers and hearts of contaminated site clams, compared to the reference site clams. The highest inter-location variability was in kidneys, compared to all other organs. The concentration of Cu, Hg, Ni and Fe in contaminated site clams was significantly higher in the gonads (15.0 ppm, 2.32 ppm, 4.3 ppm, 4.6 ppm wet weight respectively) than in kidneys, mantles and livers. The highest Cr concentration (12.5 ppm) was in the mantles. The liver was found to be the main depository of Cu (16.7 ppm) in contaminated site clams. Among the metals, Cd body burden and concentration was positively correlated to clam's wet weight/length. However, the concentrations of Pb, Hg and Cu were not correlated with clam length or weight, indicating it may be biologically regulated.;The concentrations of Ni, Cu, Cd, Pb, Mn, V and Cr in sediment were highly correlated with those in water. The levels of metals in clams from this study are generally within the range of mean values reported in the literature for other areas of the world. Only elevated levels of Hg (6.2 ppm), Pb (2.0 ppm) and Cd (4.8 ppm) from Kuwait exceeded the levels set by FAO, WHO and FDA for human consumption.