规模化猪场废水灌溉农田土壤Pb, Cd和As空间变异及影响因子分析

    Spatial variability and affecting factors of Pb, Cd and As in farmland soils irrigated by swine wastewater

    • 摘要: 为了了解长期灌溉猪场废水对农田土壤Pb、Cd和As(简称重金属)的影响,采集了河北省京安猪场周边农田的清洁区和灌溉8年猪场废水的污灌区耕层(0~20 cm)共52个土壤样品,并测定了样品中重金属的全量和有效态含量,应用GIS结合地统计学方法对重金属进行了空间结构和分布特征分析,探讨规模化猪场周边农田土壤重金属积累的影响因子及其贡献。结果表明,重金属全量和有效态含量的变异函数均很好地符合球状模型,其中全铅、有效铅、全砷、全镉和有效砷受随机性因素和结构性因素共同影响,有效镉主要受结构性因素影响。根据背景调查、重金属与pH值和土壤养分的相关性分析以及重金属变异函数分析,土壤中Cd和As污染来源为猪场废水和化肥,Pb的污染来源为化肥。富集因子分析表明,污灌猪场废水对土壤Cd和As富集效应很小,施用化肥对Pb富集有较大贡献。灌溉猪场废水会降低土壤pH值而增加重金属有效态含量,因此,需注意施用猪场废水带来重金属污染风险。

       

      Abstract: To study Pb, Cd and As (heavy metals) in soils affected by long-term irrigation of swine wastewater, 52 soil samples in the plough horizon (0~20 cm) of groundwater-irrigation farmland soils and sewage-irrigation farmland soils were collected and the total and bio-available contents of heavy metals in soils were measured respectively. And sewage-irrigation farmland soils were irrigated with swine wastewater for eight years from Jing’an swine farm in Hebei Province. Spatial variability of heavy metals was studied using Geographic Information System (GIS) technique and geostatistical analysis. The aim was to explore the affecting factors and accumulation contributions of Pb, Cd and As due to swine wastewater application. The results indicated that the spatial variability of total contents of Pb, As and Cd and bio-available contents of Pb and As in soils were dominated by random factors and structural factors together, whereas bio-available content of Cd in soils was primarily controlled by structural factors because of high self-correlation. According to the analysis of background investigated, the variogram analysis, and the correlation analysis among pH value, the contents of heavy metals and soil nutriments in soils, it could be known that the Cd and As were associated with swine wastewater and fertilizer, whereas Pb was associated with fertilizer. The enrichment factor showed that the contribution of swine wastewater for Cd and As was little, and the contribution of fertilizer for Pb was large correspondingly. Attention should be paid to the pollution risk of Pb, Cd and As because pH value in soils would decrease and the bio-available concentrations of Pb, Cd and As would increase after swine wastewater was irrigated.

       

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