Species distribution of arsenic in sediments after an unexpected emergent discharge of high-arsenic wastewater into a river

• Published in: Frontiers of environmental science & engineering 2013-08, Vol.7 (4), p.568-578
• Main Authors: Liu, Ruiping, Xu, Wei, Wu, Kun, Gong, Wenxin, Liu, Huijuan, Qu, Jiuhui
• Format: Article
• Language: English
• Subjects: Arsenates; Arsenic; Arsenite; arsenites; Binding; binding phases; biogeography; carbon; Deionization; Discharge; Earth and Environmental Science; Environment; Extraction procedures; Geographical distribution; hydrochloric acid; iron; Magnesium chloride; Manganese; Organic carbon; Particle size; pollution; Precipitates; Research Article; river sediments; river water; Rivers; Sediment samplers; Sediments; Sodium phosphate; species distribution; Surface water; unexpected discharge of high-As wastewater; Wastewater; 废水排放; 形态分布; 总砷含量; 污染事故; 物种分布; 磷酸二氢钠; 表层沉积物; 高砷废水
• ISSN: 2095-2201; 2095-221X
• DOI: 10.1007/s11783-013-0514-3

The unexpected emergent discharge of high- arsenic wastewater into water environments results in significantly increased levels of arsenic in water; however, the species distribution of arsenic in sediments has never been reported before for such cases. This study focuses on an As pollution accident in the Dasha River, and uses sequential extraction procedures with deionized water, l mol-L-1 MgC12 at pH = 8, 1 mol.L-1 NaH2PO4 at pH = 5, and 1 mol. L-1 HC1 to investigate four binding phases of arsenic （i.e., water soluble, ion-exchangeable, strongly- bound, and precipitates） in sediments at different layers in different cross-sections along the fiver. The average ratio of arsenite （As（III）） to arsenate （As（V）） was found to decrease from 0.74：1 in fiver water to 0.48：1 in sediment, owing to its higher affinity toward As（V） than As（III）. The content of arsenic in the sediments was relatively low and the maximum content was observed to be 36.3 mg-kg1 for As（IID and 97.5 mg.kg1 for As（V）. As（III） and As（V） showed different binding phases in sediments, and the average fractions of these four species were determined to be 0.09, 0.11, 0.17, and 0.63 for As（III） and 0.03, 0.14, 0.63, and 0.20 for As（V）, respectively. For all the sediment samples, the content of arsenic showed no relationship with the characteristics of the sediments such as the particle diameter, the content of organic carbon, Fe, and Mn, although a negative correlation with particle diameter was observed for the sediments in the uppermost 2-cm layer. The unexpected emergent As incident results in the high content of total arsenic in the surface sediment, which may be potential secondary source to the elevated As levels in surface water.