规模化猪场区域农田土壤重金属积累及影响评价分析

为了解长期灌溉猪场废水对农田土壤重金属的影响,采集了河北省京安猪场区域农田清洁区和灌溉8年猪场废水污灌区的耕层(0～20 cm)共52个土壤样品,并测定了样品的pH、养分和Zn、Cu、Cr、Ni、Pb和As全量和有效态含量,根据背景资料、相关分析和主成分分析确定重金属污染来源,应用富集因子分析重金属积累程度,并应用污染指数进行重金属影响评价分析。结果表明,灌溉猪场废水对土壤主要带来Zn和Cu的富集,对Ni、Cr和As几乎没有富集效应,Pb和As的富集主要由施用化肥引起。尽管灌溉8年猪场废水后土壤的Zn、Cu、Cr、Ni、Pb和As含量在安全范围内,但土壤重金属有效态含量不仅与重金属全量正相关,还与土壤pH负相关,而灌溉猪场废水会降低土壤pH,从而增加土壤重金属有效态含量。因此,长期灌溉猪场废水不但要注意土壤Zn和Cu积累,还需采取措施降低土壤Zn、Cu等重金属有效态含量以防重金属带来环境风险。

Accumulation and Assessment of Heavy Metal in Farmland Soils by Swine Wastewater Application

The total and bio-available concentrations of Zn,Cu,Cr,Ni,Pb and As,pH and the contents of soil nutrients of the 52 soil samples(0-20cm) of the groundwater-irrigated farmland soils and the sewage-irrigated farmland soils applied with swine wastewater from Jing'an swine-farm(total 8 years) were measured.The primary source of heavy metals was confirmed according to background investigation,correlation analysis and principal component analysis.Heavy metal accumulation were analyzed by enrichment factors,and the assessment of heavy metals was done by pollution index.The results indicated that swine wastewater irrigation lead to accumulation of Zn and Cu,but not for Cr,Ni and As.Accumulation of Pb and As was from fertilization principally.Swine wastewater irrigation would decrease soil pH and increase the bio-available concentrations of Zn,Cu,Cr,Ni,Pb and As.Though concentrations of Zn,Cu,Cr,Ni,Pb and As in the soils were within the safty range after the application of swine wastewater in the last 8 years,the accumulation of Zn and Cu should be paid attention and some measures should be taken to decrease the bio-available concentrations of heavy metals after long-term application of swine wastewater.