中文摘要：

为研究不同种植年限下蔬菜大棚土壤中As的总量和赋存形态的变化,在山东省聊城市市郊某百棚村种植年限为2～14a间的大棚内采集0—20cm和20—40cm土层的土壤,并在大棚外的露天农田设置对照点,分别采用王水消解法和欧盟BCR提取法对土壤中As的总量和赋存形态进行了分析,同时测定土壤pH、粒径、SOM、NO3-、NH4＋和有效磷含量等指标。结果表明,大棚内土壤As含量范围为11.3～21.4mg/kg,显著高于山东省土壤环境背景值和农田土壤中As的含量（P〈0.05）,但除种植年限为14a的大棚外,均可达到国家土壤环境质量标准要求,达标率为93.7%;各种植年限大棚土壤中As的潜在生态危害系数均〈40,具有轻微的生态危害。大棚土壤中As的平均含量随耕种年限先上升后降低,至7a后再次持续上升;在深度变化上,种植年限在5a内和10a以上的大棚0—20cm土层中As含量均高于20—40cm土层,而6～9a间大棚则正好相反。大棚土壤中各形态As所占比例表现为残渣态（87.9%）〉可还原态（8.0%）〉可氧化态（2.9%）〉酸提取态（1.2%）;酸提取态As含量随种植年限增加呈持续增加的趋势,且0—20cm土层含量明显高于20—40cm土层。相关分析表明,3种提取态As与土壤理化性质均存在不同程度的相关性,由此说明大棚土壤中非残渣态的活性As可能来源于耕种过程中施用的畜禽粪便、化肥等肥料。

英文摘要：

In order to study the change of arsenic content and speciation in soil of vegetable greenhouse with different cultivating years,soil samples were collected from 0—20cm and 20—40cm soil layers in the vegetable greenhouses which had been cultivated for 2to 14 years in a village located in the suburb of Liaocheng city,Shandong province.The soils outside the experimental greenhouses were set as the control points.Soil samples were digested by aqua regia for the analysis of total arsenic content.The fractions of arsenic were determined by the BCR sequential extraction procedure.Moreover,the basic physicochemical properties of soil including pH value,particle sizes,soil organic matter,nitrate,ammonium and available phosphorus content were also analyzed.The results showed that total arsenic content in greenhouse soil was between 11.3mg/kg and 21.4mg/kg,which was significantly higher than the background value in Shandong province and soil arsenic content in field soil outside greenhouse（P〈0.05）.However,the total arsenic contents were all lower than the national standard value for soil environment quality except that in greenhouse of14 cultivating years,and the standard-reaching rate was 93.7%.The potential ecological risk coefficients of soil arsenic were all lower than 40 in all greenhouses,indicating the light ecological risk.Soil total arsenic content in greenhouses increased at first,then decreased until the 7th cultivating year,and continually increased again with the increase of cultivating years.Arsenic contents in 0—20cm soil layer were higher than those in 20—40cm soil layer in greenhouses when their cultivating years were within 5years or over 10 years,while the opposite tendency was observed in greenhouses of 6—9cultivating years.The speciation distribution of arsenic in greenhouse soil was as follows：residual arsenic（87.9%）〉reducible arsenic（8.0%）〉oxidizable arsenic（2.9%）〉acid extractable arsenic（1.2%）.The content of acid extractable arsenicincreased with the cultivatin