Speciation Analysis And Study Of Bioavailability Of Heavy Metal In Sediment

In this paper, GBW07310 and nine sediment samples were treated with BCR procedure and four-grade-five-step procedure with the intention to indicate the high accuracy of the four-grade-five-step procedure. And the concentrations of heavy metal of different fractions were got. At the same time, six mixed organic acids of low molecular weight which produced by plant roots were used to extract heavy metal in sediment samples with different extract procedures.The chemical and toxicological characteristic of heavy metals, which association with the organic matter and sulphide, is different. The two different speciations of heavy metals have different influences on the migration, conversion and toxicity of metals.The extract results that treated with GBW07301 and sediment samples indicated that the fraction of different biological availability could be separated; the pre-extraction of the fraction bound to the organic matter was eliminated. And so, the four-grade-five-step procedure could distinguish the metal speciation bound to organic matter from that to the sulphide completely on different sediment samples, showing the good adaptability on different locations.The extract results of mixed organic acids showed that the concentration of heavy metal extracted in one step contained exchengeable fraction, reducible fraction and oxidable fraction. Extracting in one step is the best extract procedure which could totally and exactly show the activate concentration and extract concentration of heavy metal in sediments by mixed organic acids. The concentration of heavy metal extracted by mixed organic acids in one step equals to the concentration of heavy metal that could be absorbed by plants.In the three fractions of heavy metal in sediment samples that extracted by mixed organic acids, the most extract percentage of heavy metal is exchengeable fraction , the second is oxidable fraction, and the least is reducible fraction. So we could conclude that the exchengeable fraction of heavy metal is the most easily activate and extract fraction absorbed by plants, oxidable fraction is the second, and reducible fraction is the least.In the six kinds of mixed organic acids simulated in the experiment, for the same heavy metal, the concentration extracted by mixed organic acids of grass'root is the largest, and the concentration extracted by mixed organic acids of radish's root is the lowest.