天津污灌区菜地土壤团聚体中有机碳和重金属含量特征

以天津某污灌菜地土壤为研究对象,分析干筛法所得不同粒径土壤团聚体颗粒中有机碳及重金属含量特征.结果表明,土壤团聚体粗大颗粒(2 mm)含量最大,约为70%.0.25～0.5 mm粒级团聚体中Cu、Zn、Cd和Pb含量最高,Cr含量在5～8 mm粒径团聚体中最高,As在不同颗粒中含量差异较小,不同重金属元素含量随土层深度增加而减小.污灌土壤中重金属富集因子表现为Cd Pb Zn Cu Cr As,在0.25～0.5 mm粒级团聚体颗粒中Cu、Zn、Cd和Pb分布因子最高,而5～8 mm粒径团聚体中重金属负载因子最大.土壤有机碳含量整体上随团聚体粒径增加表现为先增加后降低,不同粒径团聚体中Cu、Cd、Pb和As含量与有机碳含量呈显著正相关(p0.05).

Characteristics of organic carbon and heavy metals in aggregates of wastewater irrigation soils of Tianjin

Organic carbon and heavy metal concentrations in different sizes of soil aggregates in wastewater irrigated vegetable soils of Tianjin were studied. Results showed that >2 mm soil aggregate was largest, being about 70%. The highest contents of heavy metals were distributed in the 0.25~0.5 mm aggregate for Cu, Zn, Cd and Pb, and in the 5~8 mm aggregate for Cr, while there was no difference among the concentration of As in different size aggregates. The content of different heavy metals decreased with increasing of the depth of soil layer. Heavy metal enrichment factors in polluted soil was Cd > Pb > Zn > Cu > Cr > As, Cu, Zn, Cd and Pb showed the highest distribution factor in the aggregate particle of 0.25~0.5 mm, and the 5~8 mm particle size aggregates had the largest loading factor of heavy metals. The soil organic carbon content as a whole increased first and then decreased with the aggregate particle size increasing. The contents of Cu, Cd, Pb and As in different particle size aggregates were positively correlated with organic content (p<0.05).