大同盆地浅层含水层沉积物中砷的生物可利用性评价

摘要

以采自大同盆地野外试验场的含水层沉积物为研究对象，调查高砷含水层中生物可利用性砷的含量及其影响因素。经实验室测定，沉积物总体呈碱性，Al、Fe等金属元素含量较高。利用连续提取法发现沉积物中砷结合形态主要为无定形和低结晶铁铝氧化物结合态，其次是残余态砷。其中铁铝氧化物形态的砷所占比例达53.54％，非专性吸附态和专性吸附态占14.33％，生物可利用形态的砷较少，这与体外模拟方法测定的生物可利用性砷含量较低吻合。体外模拟实验还发现：肠阶段生物可利用性砷含量比胃阶段低，生理学提取法（PBET）和体外消化法（IVG）测定的生物可利用性砷差异较小。%The aquifer sediment samples collected from the test site of high arsenic level groundwater in Datong Basin were used to investigate the content of bioavailable arsenic and interaction with environmental conditions. The results showed that the contents of Al and Fe were high in these alkaline sediments.Amorphous and poorly crystalline of As with Fe and Al oxides were dominant and followed by residual phase in these sediments.It was 53.54% of all arsenic speciation for Fe and Al oxides containing arsenic,only 14.33% for adsorbed arsenic. Therefore,content of bioavailable arsenic was low in the sediment samples,which was consistent with the result of vitro simulative assay.We also found from vitro simulative assay that the content of bioavailable arsenic was lower in intestine phase than in the stomach phase.The concentration difference of bioavailable arsenic is low between physiologically based extraction test (PBET)and vitro gastrointestinal method (IVG).