[Pollution Characteristics and Source Analysis of Heavy Metals in Farmland Soils in the Taige Canal Valley]

To determine the distribution characteristics of heavy metal pollution in farmland soils and related influencing factors in the Taige canal valley, and guarantee soil environmental quality and safety of agricultural products, 118 topsoil samples were collected from the Taige canal valley's farmland soils, and contents of chromium (Cr), mercury (Hg), arsenic (As), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), and cadmium (Cd) were measured. A single factor index and comprehensive index were used to assess soil heavy metal contamination with the soil background value of the Taihu Lake basin as the evaluation standard. The multivariate statistical analysis and the geostatistical analysis were combined to identify and apportion the pollution sources of soil heavy metals. The results showed that:The average concentrations of Cr, Hg, As, Cu, Zn, Ni, Pb, and Cd in soils were 63.25, 0.25, 7.83, 35.24, 77.25, 31.48, 38.37, and 0.16 mg·kg^-1, respectively, all of which except for Cr and As were higher than the local soil background values. The content of each heavy metal in most soil samples were lower than the risk screening values for soil contamination of agricultural land. The comprehensive index showed that the degree of pollution of soil heavy metals were at a slightly polluted level in 87.29%, moderately polluted level in 5.93%, and severely polluted level in 6.78% of the sampling. Hg, Cu, Zn, Pb, and Cd in the watershed soil were affected by agricultural activities and atmospheric deposition. Cr and Ni were affected by the parent material and industrial production activities. As was mainly derived from the parent material.