0.3 mol/L phosphoric acid and 0.1 mol/L ascorbic acid were used to extract the sediment samples following a microwave-assisted extraction procedure. 2.0 mmol/L NaH2PO4/0.2 mmol/L EDTA (pH 6.0) were used as the mobile phase, to determine the concentration of As( Ⅲ ), As( Ⅴ ), MMA and DMA in the extracted liquid by high performance liquid chromatography-inductiuely coupled plasma-mass spectrometry (HPLC-ICP-MS). The chromatographic peaks of 4 arsenic species are completely separated in 10 min.The linear correlations are satisfactory. The recoveries are between 94.2％ and 110％. The extraction efficiency of arsenic species were 80.4 ％-98.7 ％. The results show that arsenic species in the surface sediments of Taihu Lake are mainly inorganic arsenic. And organic arsenic species are not detected. The content of As( Ⅴ ) in the samples are higher than that of As( Ⅲ ), which indicate that the surface sediments of Taihu Lake basically are in the oxidizing environment. In the recent 20 years, the arsenic content in the sediment of Taihu Lake had increased evidently. The arsenics were inorganic species in the vertical profiles of sediment, and there were no remarkable differences for the relative ratios of the arsenic species in each section.%以0.3 mol/L磷酸和0.1 mol/L抗坏血酸为提取试剂,对沉积物样品进行微波萃取.以2.0 mmol/LNaH2PO4/0.2 mmol/LEDTA(pH 6.0)为流动相,采用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用技术测定萃取液中As(Ⅲ)、As(V)、MMA和DMA的含量.4种形态砷的色谱峰在10 min内可以得到完全分离,标准曲线线性良好,样品的加标回收率范围为94.2%～110%,样品中砷形态的提取效率为80.4%～98.7%.研究表明,太湖表层沉积物中的砷主要为无机形态,未检出有机砷形态,As(V)形态的含量高于As(Ⅲ),说明太湖表层沉积物基本上处于氧化性沉积环境中.近20年来,太湖湖底沉积物中砷的含量有了显著增加.检测的沉积剖面沉积物中砷的形态亦为无机形态,各沉积剖面沉积物中砷形态的相对比例没有显著差异.
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