污泥土地利用对土壤中重金属形态的影响

土地利用是资源化利用城市污水厂污泥的有效途径，随污泥中的营养成分一起进入土壤中的还有其中的重金属元素，它们有可能成为一种环境安全的隐患。本实验所用的土壤为污泥经过无害化及稳定化处理后，与上海潮滩沙土按不同比例(干污泥质量比)混配而成。种植前后分别对沙土、污泥及混配土的重金属含量及形态进行测试。选择几种花卉植物，如菊花(Calendula officinalis）等进行植物种植试验，一个生长季后对植物中的重金属含量及形态进行测试。应用Tessler连续提取法，对污泥中的重金属进入土壤后，土壤中重金属的含量、赋存状态等方面的规律进行研究，发现污泥的土地利用会明显增加土壤中的重金属含量，而且重金属的形态也有明显的变化，可交换态和碳酸盐结合态的重金属含量有明显的增加；如长期使用，则必须采取相应的措施，以消除有害的影响。

Effects of sewage sludge application to land on species of heavy metals in soil

land application is one of the important disposal for resource reuse of sewage sludge. With humus and nutrients such as nitrogen, phosphorus, potassium and micronutrients, heavy metals of sewage sludge entry the soil when sewage sludge was applied to land. The heavy metals such as zinc, copper, lead, nickel, mercury and cadmium can be accumulated in soil due to the application over many years, and they could be released at the levels being harmful to plant, animals and humans by the food chain. In this paper, the soil used in the experiment was mixed with sandy soil from the beach and sewage sludge in different proportion. Some flower plants such as chrysanthemum (Calendula officinalis) were planted in the mixed soil. After one growth season, the concentrations and species of the heavy metals in the soil was investigated. Research results show that the concentrations and activity of heavy metals increased when the sludge entry the soil. The environmental risk of heavy metal must be considered before large volumes of sewage sludge is applied to land.