硫铁矿冶炼区不同土地利用方式及土壤类型对重金属迁移的影响

为探讨硫铁矿冶炼区不同土地利用方式和土壤类型对重金属元素迁移的影响，采集了毕节市林口废弃硫铁矿冶炼厂内耕地砂壤土及附近林地石灰土表层和深层样共40组。室内测试土壤理化指标Pb、Zn、Cd全量和有效态含量，并对重金属元素含量的水平和垂直分布特征及重金属元素含量的相关性进行了讨论。结果表明:土壤中Pb和Zn的含量均符合土壤环境质量二级标准值，耕地表层土壤Cd含量是贵州省农业土壤背景值的7倍。土壤Cd有效态含量占全量的比值最大，而Pb和Zn有效态含量占全量的比值差别较小。耕地砂壤土Zn和Cd的全量随剖面深度的增加表现为先增大后减小，Pb呈减少的趋势；Pb和Zn的有效态含量随剖面深度的增加而减少，Cd有效态含量呈波动变化。林地石灰土中Pb、Zn、Cd的全量和有效态含量均随剖面深度的增加而减少，且Pb、Zn、Cd全量之间及全量与有效态含量之间都具有显著的正相关关系，而在耕地中各元素的相关性不明显。土壤频繁的扰动和偏酸性的环境有利于重金属垂向迁移。 

Effects of different land use and soil type on the migration of heavy metals in a pyrite smelting area

The objective of this work is to understand the impact of the Weihe pyrite smelting on the surrounding environment and migration of soil heavy metals due to different land uses and soil types. In total 12 surface soil samples and 28 deep soil samples on 4 profiles were collected from the cultivated land and woodland in or near the smelting area. The total and available contents of heavy metals and soil chemical and physical properties were analyzed. The results indicate that the concentrations of total lead (as Pb) and zinc (as Zn) in the soils are generally less than the threshold levels of China Environmental Quality Standard for Soils（GB 15618-1995 Class II）, while the concentrations of total and available cadmium (as Cd) in soils exceed the soil background values of Guizhou Province. Cd has the highest value, while the difference between Pb and Zn is relatively small. The total contents of Zn and Cd in the farmland soils first increase and then decrease at depth, but Pb keeps a decreasing trend. The available contents of Pb and Zn decrease with the depths, while Cd shows a fluctuating trend. The total and available contents of the three heavy metals in woodland soils exhibit a decreasing trend at depth. There is a remarkable positive correlation between the total contents and available contents of Pb, Zn and Cd, and also a remarkable positive correlation among the total contents of the three heavy metals in woodland lime soils, but not in farmland soils. A soil environment with frequent disturbances and an acidic condition is favorable for the migration of heavy metals in a vertical direction.