Arsenic Speciation in Sediments of Poyang Lake and Its Main Branches

摘要

In this paper, arsenic speciations in sediments of Poyang Lake and its main branches were investigated in much details. Sediment samples were collected in different sites of Poyang Lake and its branches. Arsenic is quantified with micro-hydride generation- atomic fluorescence spectrometry. Five chemical combination speciations of arsenic in the sediments are differentiated by the commonly accepted five-step sequential extraction method. The results demonstrated that the total amount of arsenic in all sediments is in accordance with the background value of Poyang Lake district. Total arsenic, trivalent and pentavalent arsenic in the samples are mainly bounded to organic matter or existed as residual forms as well. Three reactive speciations including exchangeable species, carbonate bounded and Fe-Mn bounded forms account for about 20% of the total five fractions. The content of reactive speciations are varied with pH value, oxiding-reducing conditions and organic matter in the sediments, et al. Results also indicated that arsenic levels were much higher in certain branch sediments than that in Poyang lake, which can be explained by the stream pollution resulted from the drainage of minerals mining waste upriver or the sanitary sewage drainage.