农田施用沼液的重金属污染评价及承载力估算——以江苏滨海稻麦轮作田为例

以江苏滨海稻麦轮作田为对象,研究沼液施用0,3,5a对土壤和作物籽粒重金属（Cu、Zn、Pb、Cd）含量的影响,评价其污染风险并估算农田沼液承载力.结果表明：沼液施用3,5a后,土壤和作物籽粒中Cu、Zn、Pb、Cd均未超标,内梅罗指数与土壤和农产品综合质量指数显示农田重金属污染程度属于清洁.土壤Cu和Zn显著富集,沼液施用5a后,小麦季土壤Cu、Zn含量分别为22.59,63.08mg/kg,较未施用分别提高了19.52%和28.89%.水稻季土壤Cu、Zn含量分别为26.12,78.74mg/kg,较未施用分别提高了27.73%和31.80%.小麦和水稻籽粒Zn含量随沼液施用年限增加而增加（P<0.05）,沼液施用5a分别达到25.07,30.98mg/kg,较未施用分别提高了23.50%和16.29%.小麦季和水稻季0~15cm土壤中Cu的累积速率分别为0.74,1.13mg/（kg·a）,Zn的累积速率分别为2.83,3.80mg/（kg·a）.基于土壤重金属累积速率,江苏滨海稻麦轮作田沼液安全施用年限为63a.

Assessment of heavy metal pollution and bearing capacity estimation of continuous biogas slurry application on cropland: A case study of the coastal rice-wheat rotated farmland in Jiangsu,China

In order to evaluate the pollution risk and estimate the bearing capacity, the coastal rice-wheat rotated farmland in Jiangsu Province was studied to investigate the effects of biogas slurry application for 0, 3, and 5years on heavy metal (Cu, Zn, Pb, Cd) contents in soil and crop grains. Cu, Zn, Pb, and Cd contents in soil and crop grains did not exceed the national standard limits after 3 and 5years of biogas slurry application, and the degree of heavy metal pollution in farmland met the requirements of cleaning according to Nemerow index and the Influence Index of Comprehensive Quality. The Cu and Zn contents in soil enriched significantly after 5years of application of biogas slurry and the contents of Cu and Zn in wheat and rice season were 22.59 and 63.08mg/kg (26.12 and 78.74mg/kg), which were 19.52% and 28.89% (27.73% and 31.80%) higher than those grains without application. As the increasing of application age of biogas slurry, the content of Zn in crop grains increased significantly (P<0.05) and the Zn contents in wheat and rice grains reached up to 25.07 and 30.98mg/kg after 5years of biogas slurry application, which was 23.50% and 16.29% higher than those grains without application. The accumulation rate of Cu and Zn in soil (0~15cm depth) was 0.74mg/(kg·a), 2.83mg/(kg·a) and 1.13mg/(kg·a), 3.80mg/(kg·a) for wheat and rice season, respectively. Based on the accumulation rate of heavy metals in soil, the safe application period of biogas slurry in coastal rice-wheat rotated farmland was 63years.