CHEMICAL PARTITIONING AND BIOAVAILABILITY OF LEAD AND NICKEL IN AN ESTUARINE SYSTEM

摘要

Sediments, water, and biota of an estuarine system were analyzed for concentrations of lead and nickel. Sediments were sequentially extracted to obtain the different chemically extractable fractions (exchangeable, carbonate bound, Fe/Mn-oxide bound, organically bound, and residual fractions) of these metals. Concentrations of these metals in the soft tissue of an estuarine bivalve Villorita cyprinoides var. cochinensis were correlated with the concentrations of these metals present in the various sediment fractions, dissolved, and paniculate phases in water. The degree of correlation between these various environmental variables and biological factors was considered as the index of bioavailability. Metal concentrations in the soft tissue and paniculate phase of water were divided by the corresponding concentrations in the dissolved phase in water to obtain the bioconcentration ratio (BCR) and metal partitioning ratio (MPR), respectively. These ratios were found to be useful in quantifying the metal bioavailability. The relationship between other biological factors and environmental variables is also presented and discussed.