• 关键词：砷(As)  化学形态  富营养化  风险评价  风险指数编码法(RAC)

• 基金项目：国家自然科学基金（No.21277136）；国家国际科技合作专项（No.2011DFB91710）

• 车霏霏
• 1. 中国科学院城市环境研究所, 城市环境与健康重点实验室, 厦门 361021;2. 中国科学院大学, 北京 100049

• 甄卓
• 1. 中国科学院城市环境研究所, 城市环境与健康重点实验室, 厦门 361021;2.中国科学院大学, 北京 100049

• 王大鹏
• 1. 中国科学院城市环境研究所, 城市环境与健康重点实验室, 厦门 361021;2. 中国科学院大学, 北京 100049

• 颜昌宙
• 中国科学院城市环境研究所, 城市环境与健康重点实验室, 厦门 361021

• 摘要：以太湖不同营养水平湖区为研究对象，采用改进的砷（As）形态连续提取法对表层沉积物中As的化学形态进行分析研究，探讨了沉积物中总砷（TAs）和As形态的分布特征及其与沉积物中营养盐和总有机碳（TOC）的相关性，并利用潜在生态风险评价（E_rⁱ）和风险指数编码法（RAC）评估了各湖区沉积物中As的生态风险水平.结果表明，各湖区表层沉积物中TAs的平均含量约为14.23~16.59 mg·kg^-1，其中，竺山湾的TAs平均含量相对最高.As形态表现出明显的空间分布特征，其中，北部富营养湖区（竺山湾、梅梁湾、贡湖湾）中的有效态As（非专性吸附态和专性吸附态）与潜在有效态As（无定形氧化铁结合态、晶体形氧化铁结合态、有机结合态）的含量与百分比均高于中营养水平的南太湖，而北部湖区的残渣态As含量则低于南太湖.Pearson相关分析结果显示，除晶体形氧化铁结合态As和残渣态As外，沉积物总氮（TN）、总磷（TP）和TOC与其他As形态均存在显著的正相关关系.潜在生态风险评价结果表明，各湖区沉积物TAs均处于低风险；而RAC评价结果表明，各湖区沉积物的有效态As基本处于中等风险水平，且北部湖区的RAC指数均明显高于南太湖.

• Abstract：A modified sequential extraction procedure for arsenic (As) fractions was applied to analyze the chemical fractions of As in the surface sediments from different eutrophic regions of Lake Taihu, including Zhushan Bay, Meiliang Bay, Gonghu Bay and Southern Lake Taihu. Spatial distributions of total arsenic (TAs) and As fractions were examined in these collected sediments, as well as their correlations with nutrients and total organic carbon (TOC). In addition, ecological risk of As were evaluated by the potential ecological risk assessment (Eⁱ_r) and risk assessment code (RAC) in these collected sediments. Results show that the average concentrations of TAs ranged from 14.23 mg·kg^-1 to 16.59 mg·kg^-1 with the maximum value in Zhushan Bay. The distributions of As fractions exhibited obvious spatial difference. The concentrations and proportions of available As (including non-specifically sorbed As and specifically sorbed As) and potential available As (including amorphous Fe oxides bound As, crystalline Fe oxides bound As, and organo-As compounds) were higher in northern eutrophic regions (Zhushan Bay, Meiliang Bay and Gonghu Bay) than in Southern Lake Taihu. In comparison, residual As in northern regions were lower than those in Southern Lake Taihu. Furthermore, various As fractions were positively correlated with total nitrogen (TN), total phosphorus (TP) and TOC, except for crystalline Fe oxides bound As and residual As. The risks of TAs in the four regions were in low level based on Eⁱ_r index. Meanwhile, the risks of available As in these sediments were almost in moderate level according to RAC index. Moreover, the RAC values of As were obviously higher in northern regions than in Southern Lake Taihu.

• Key words：arsenic (As)  chemical fraction  eutrophication  risk assessment  risk assessment code (RAC)

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