湖南攸县典型煤矿和工厂区水稻田土壤镉污染特征及污染途径分析

Characteristics and Inputs of Cd Contamination in Paddy Soils in Typical Mining and Industrial Areas in Youxian County,Hunan Province

为了解湖南攸县水稻田土壤镉污染特征及污染途径，选择煤矿区、煤矿工厂区和工厂区三类典型样地进行农田土壤、灌溉水渠底泥及典型含Cd工业产品和副产品如煤、煤矸石和水泥等介质中Cd含量的分析研究．结果表明：①三类样地农田和表层自然土壤以及灌溉渠底泥中的平均Cd含量都超过了土壤环境质量标准0．3mg·kg^-1，煤矿区和煤矿工厂区的煤矸石Cd含量以及工厂区的水泥Cd含量都与相应自然土壤中含量相似，工厂区Cd的大气沉降通量较高；②三类样地土壤Cd剖面垂直分布差异明显，煤矿区和煤矿工厂区0～40cm剖面的农田土壤Cd较自然土壤高，煤矿区农田和自然土壤中的Cd垂直向下迁移的潜力较高；③煤矿工厂区和工厂区点源下风向农田表土Cd含量明显比上风向低；④攸县煤矿区和煤矿工厂区农田土壤Cd的灌溉水输入途径较为重要，而煤矿工厂区和工厂区农田土壤Cd的大气输入途径也较为明显．

In order to explore input pathways and pollution characteristics of Cd contamination in paddy soil in Youxian, Hunan Province, Cd contents in paddy soils, sediments of irrigation canals, typical mineral and industrial products such as coal, gangue and cement were analyzed. It was suggested that the average contents of Cd both in surface paddy soil and the corresponding natural soil were higher than the soil quality standard 0.3 mg·kg^-1. Gd contents in gangue and cement were similar as those in the corresponding natural soils. The atmosphere deposition of Cd was the highest in factory area. The profiles of Cd in 0-100 cm paddy soil and 0-40 cm in natural soils varied significantly from the upper to the lower layer. Cd contents in 0-40 cm layer in paddy soil were much higher than those in corresponding natural soils in mineral and mineral-factory areas. The potentiality for downward movement of Cd in soils in mineral area was the highest among the three studied areas. It suggested Cd contents in surface paddy soil were higher in upwind areas than those in downwind areas in mineral-factory and factory areas. It could be concluded that the main input pathways of Cd in mineral and mineral-factory areas were from irrigation water, while contribution of atmosphere deposition in mineral-factory and factory areas was also very significant.