中文摘要：

在开封市不同功能区布设8个土壤采样点，分别于1994年和2012年在同地点采集表层（O～20cm）样品，测定土壤As、Pb、Cd和Hg含量，用地积累指数（Igeo）法和污染负荷指数（PLI）法开展重金属污染评价．结果表明：近20a来开封城市土壤重金属污染程度总体上呈下降趋势，但2012年仍存在不同程度的污染，其中以工业区土壤污染最为严重，其次是文教区、行政商业区、休闲娱乐区．与1994年相比，2012年全部样点Pb污染程度以及大部分样点As污染程度出现上升趋势，主要原因是近20a来机动车辆和燃煤数量的快速增加；而大部分样点Hg和Cd污染程度有所下降，主要原因是近20a来工业企业陆续迁出城区或处于倒闭、停产、半停产状态，以及绿地面积增加等．城市土地利用／覆盖变化对土壤重金属污染具有重要影响，由农田转换为城市用地之后，土壤重金属含量和污染程度增加．今后应加强城市土壤多种重金属的定位和连续监测．

英文摘要：

The concentrations of As, Pb, Cd and Hg in the samples were measured by using standard methods of China, and heavy metal pollutions in the city soil were evaluated using geo-accumulation index （Igeo） and pollution load index （PLI）. Eight topsoil （0-20 cm） samples have been collected from different locations in Kaifeng City in 1994 and eight from the same sites in 2012. The results show that：Firstly, heavy metal pollution in Kaifeng city has been descending during recent 20 years, but not eliminated completely in 2012. The most contaminated sample was collected from the industrial district, and the subsequence culture-education district, administration-commerce district and leisure-entertainment district. Secondly, the concentrations of Pb in all urban samples, and As in most samples of 2012 are higher than those of 1994, mainly because of the rapid increase of motor cars and domestic garbage. Meanwhile, the concentrations of Hg and Cd in most soil samples of 2012 are lower than those of 1994, since most industrial enterprises have moved out of Kaifeng City or shut down, and the environmental facilities are widely developed in recent 20 years. Land use and land cover change （LUCC） can affect soil metal pollution in urban area. If farmland is transformed into urban land, heavy metal pollutions in soils for this area will become more serious.