城市生活污泥农用对作物和土壤中汞的影响

采用田间小区试验,研究了连续5a施用污泥条件下汞(Hg)在小麦/玉米轮作体系中累积及转运特征.田间试验包括5个处理:施用化肥处理(S0)和4个施用污泥处理,污泥用量分别为4.5t/hm2(S1)、9t/hm2(S2)、18t/hm2(S3)和36t/hm2(S4).结果表明,随着污泥施用年限的增加土壤中Hg累积量显著增加,污泥中所含Hg的投入量与土壤中Hg的累积量之间存在显著的线性回归关系;污泥中的Hg主要累积在表层土壤(0~20cm),累积率达到90%以上;当污泥中的Hg含量低于污泥农用时污染物控制标准限值(GB18918-2002)时,在用量低于2400t/(hm2·a)条件下,连续5a施用并未对小麦和玉米地上部Hg含量产生显著影响.

Effects of domestic sewage sludge on the accumulation and transfer of mercury in crop-soil system

A field experiment was carried out to investigate the effects of domestic sewage sludge on accumulation and transfer of mercury in soil in wheat/maize rotation system. Five treatments were chosen for this work: chemical fertilizer without sewage sludge (S0), chemical fertilizer with 4.5t/hm2 sewage sludge (S1), chemical fertilizer with 9t/hm2 sewage sludge (S2), chemical fertilizer with 18t/hm2sewage sludge (S3), and chemical fertilizer with 36t/hm2 sewage sludge (S4). The results showed that the Hg concentration obviously increased with age of the sewage sludge utilization. There was a significant linear relationship between the input amount of Hg in sewage sludge and accumulated amounts of Hg in soil. The Hg mainly accumulated in 0-20cm topsoil and accumulation rate could reach 90%. The 5-year continuous application of sewage sludge did a little effect on the Hg concentration in crop grains and shoots when the dose of sewage sludge was less than 2400t/(hm2×a), in which the Hg concentration of sewage sludge was less than the Chinese sludge agricultural pollution control standard limit (GB18918-2002).