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在快速城镇化的背景下,通过转换农用地类型实现研究区重金属超标农用地的安全利用。采用单因子指数法对研究区农用地重金属元素Cd、Pb、Cu污染状况进行评价,依据农用地安全利用标准,采用地类转换的方式调整超标程度严重的农用地类型。结果表明:(1)地类转换对研究区重金属超标农用地安全利用影响显著。从相对污染程度变化情况来看,所有点位相对污染程度均降低。绝大部分点位污染等级降低一到三级不等,个别点位虽单因子污染指数减小,但污染等级没有发生变化。(2)从地类转换后的结果来看,有些地类转换调整之后虽然相对污染等级降低,但污染指数仍大于3;另一种情况是经过地类转换,污染指数有所降低,但污染等级并未发生改变。(3)从分布情况来看,主要分布在中部城镇建成区附近,城镇周边分散有个别地块,地类转换之后,超标程度较重区域向集中分布区域中心缩减,城镇周边明显减少。
Under the background of rapid urbanization, the safe use of excessive heavy metal in agricultural land in the research area is realized by converting the types of agricultural land. The single factor index method was used to evaluate the pollution status of heavy metals Cd, Pb and Cu in agricultural land in the study area. According to the standard of safe use of agricultural land, the type of agricultural land with serious overriding degree was adjusted by means of land conversion. The results showed that: (1) Land-use conversion had a significant impact on the safe utilization of farmland over-standard for heavy metals in the study area. From the relative changes in the level of pollution point of view, all the relative pollution levels are reduced. The pollution level of most points decreased from one level to three levels. Although the single factor pollution index decreased, the pollution level did not change. (2) According to the results after land conversion, although the relative pollution level is reduced after some land conversion and adjustment, the pollution index still exceeds 3; on the other hand, the pollution index is reduced after land conversion, but the pollution index is reduced, but the pollution Rank has not changed. (3) According to the distribution, it is mainly distributed in the vicinity of the built-up area of central cities and towns. There are some plots scattered around the towns. After the land-type conversion, the heavily-exceeded areas shrink to the centers of concentrated distribution and the surrounding areas of cities and towns are obviously reduced.