Du Laing G, Chapagain S K, Dewispelaere M, Meers E, Kazama F, Tack F M G, Rinklebe J, Verloo M G
Laboratory of Analytical Chemistry and Applied Ecochemistry Ghent University, Faculty of Bioscience Engineering, Coupure Links 653, B-9000, Ghent, Belgium.
J Environ Monit. 2009 Apr;11(4):873-81. doi: 10.1039/b815875d. Epub 2009 Feb 25.
We aimed to assess the presence and availability of arsenic (As) in intertidal marshes of the Scheldt estuary. Arsenic content was determined in soils sampled at 4 sampling depths in 11 marshes, together with other physicochemical characteristics. Subsequently, a greenhouse experiment was set up in which pore water arsenic (As) concentrations were measured 4 times in a 298-day period in 4 marsh soils at different sampling depths (10, 30, 60 and 90 cm) upon adjusting the water table level to 0, 40 and 80 cm below the surface of these soils. The As content in the soil varied significantly with sampling depth and location. Clay and organic matter seem to promote As accumulation in the upper soil layer (0-20 cm below the surface), whereas sulfide precipitation plays a significant role at higher sampling depths (20-100 cm below the surface). The As concentrations in the pore water of the greenhouse experiment often significantly exceeded the Flemish soil sanitation thresholds for groundwater. There were indications that As release is not only affected by the reductive dissolution of Fe/Mn oxides, but also by e.g. a direct reduction of As(V) to As(III). Below the water table, sulfide precipitation seems to lower As mobility when reducing conditions have been sufficiently established. Above the water table, sulfates and bicarbonates induce As release from the solid soil phase to the pore water.
我们旨在评估斯海尔德河河口潮间带湿地中砷（As）的存在情况和可利用性。测定了11个湿地中4个采样深度的土壤中的砷含量，以及其他理化特性。随后，开展了一项温室试验，在将地下水位调整至这些土壤表面以下0、40和80厘米的情况下，在298天内对4种不同采样深度（10、30、60和90厘米）的湿地土壤中的孔隙水砷（As）浓度进行了4次测量。土壤中的砷含量随采样深度和位置的不同而有显著差异。粘土和有机物似乎促进了砷在上层土壤层（地表以下0-20厘米）的积累，而硫化物沉淀在较高采样深度（地表以下20-100厘米）起着重要作用。温室试验中孔隙水中的砷浓度常常显著超过弗拉芒地区地下水土壤卫生阈值。有迹象表明，砷的释放不仅受铁/锰氧化物还原溶解的影响，还受例如将五价砷直接还原为三价砷等因素的影响。在地下水位以下，当还原条件充分建立时，硫化物沉淀似乎会降低砷的迁移性。在地下水位以上，硫酸盐和碳酸氢盐会促使砷从土壤固相释放到孔隙水中。
