尕海湖泊表层沉积物中汞和砷的赋存特征、生物有效性及其风险性评价研究
Study on the occurrence characteristics, bioavailability and risk assessment of mercury and arsenic from thesurface sediments inLake Gahai
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摘要: 本文报道了柴达木盆地尕海湖泊表层沉积物中重金属元素汞和砷的Tessier化学形态分析测试结果，基于富集因子法（EF）、地质积累指数法（Igeo）、潜在生态风险指数法（PERI）、风险评价编码法（RAC）和次生相与原生相分布比值法（RSP）对研究区内汞和砷的污染程度、潜在生态风险水平以及生物有效性进行了评价。研究结果表明，汞和砷元素的平均含量值分别为0.07 mg/kg和37.28 mg/kg，在空间分布上呈现不均匀特征，且其含量变化趋势存在不同步性。汞和砷主要以残渣态为优势形态，分别占其总量的81.12%和60.49%；劣势组分为碳酸盐结合态，分别占其总量的2.27%和0.52%。RAC评价结果为Hg>As，而RSP评价结果则是As>Hg。Igeo和PERI评价结果显示汞和砷的总体生态风险趋势基本一致，汞的生态风险远高于砷的生态风险。人类活动产生的人为源影响日益凸显，重金属元素譬如汞已成为全国性的污染物，需要引起足够的重视。Abstract: The results of heavy metal elements Hg and As from the surface sediments of Lake Gahai in Qaidam Basin determined by Tessier sequential chemical extraction procedures are reported. Based on the enrichment factor (EF), geo-accumulation index (Igeo), potential ecological risk index (PERI), risk assessment code (RAC) and the ratio of secondary to primary phase distribution (RSP) methods, the pollution degree, potential ecological risk level and bioavailability of Hg and As in the study area were evaluated. The results showed that the average contents of Hg and As element was 0.07 mg/kg and 37.28 mg/kg, respectively, showing an uneven spatial distribution and asynchronous trends in content variation. Hg and As were predominantly presented in the residual phase, accounting for 81.12% and 60.49% of their total amounts, respectively, the subordinate fractions were the carbonate-bound forms, accounting for 2.27% and 0.52% of their total amounts, respectively. The RAC evaluation results suggested Hg>As, while the RSP evaluation results indicated As>Hg. The Igeo and PERI evaluation results showed that the overall ecological risk trends for mercury and arsenic were generally consistent, with the ecological risk of Hg being much higher than that of As. The impact of anthropogenic sources generated by human activities is becoming increasingly prominent, and the heavy metal elements such as Hg has become nationwide pollutant that requires sufficient attention.
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