Heavy Metals in Agricultural Soils of the Lihe River Watershed, East China: Spatial Distribution, Ecological Risk, and Pollution Source

Abstract

Concentrations of cadmium, chromium, copper, nickel, lead, and zinc in agricultural soils at 32 sites in the Lihe River Watershed of the Taihu region, East China, and their potential ecological risks and possible sources were investigated. Enrichment factor analysis demonstrated enrichment in the order Cd > Pb > Zn > Cu > Ni > Cr. The potential ecological risk index and risk assessment code analyses indicated that, of the metals studied, Cd posed the most significant ecological risk in the study area. Statistical analyses, GIS mapping, and enrichment factor analysis suggested that Cd, Pb, Cu, and Zn were derived mainly from anthropogenic sources, including agricultural, industrial, and vehicular emissions, while Cr and Ni were mainly from natural sources. Positive matrix factorization revealed that Cd, Cr, Cu, Ni, Pb, and Zn were sourced from industrial and vehicular emissions (73.7%, 21.3%, 71.4%, 20.3%, 75.0%, and 62.2%, respectively), the agricultural sector (26.3%, 36.3%, 6.8%, 38.9%, 15.7%, and 6.9%, respectively), and parent materials (0%, 42.4%, 21.8%, 40.8%, 9.2%, and 30.9%, respectively). It was recommended that strategies be implemented to reduce industrial point-source pollution.

Evaluation of Heavy Metals Contamination in Agricultural Soils

“…The high concentration of Cr in WWI soil may be due to the dumping of waste by printing and chemical industries in the drain. The mean concentration of Cr in the agricultural soils in the present study was higher than the concentration of Cr in agricultural soils of India [36], and other studies from the world [15,19].…”

“…Where C i is the metal concentration and C Fe is the concentration of the reference element (Fe) in the sample and continental crust. Background values for EF calculation were taken the same as taken for Igeo calculation.An EF value of 0.5-1.5 indicates that a metal derives primarily from crustal materials through natural weathering processes, while EF> 1.5 indicates that a signi cant portion of metal arises from non-crustal or anthropogenic processes [19].…”

“…the higher the range of human activities, the higher the coe cient of variation will be. It has been classi ed in to three categories: low variation (CV <0.15), medium variation (0.15 < CV < 0.36) and high variation (CV > 0.36), and is calculated as given in equation 3 [19].…”

“…Ecological risk assessment is a technique used to identify the environmental impacts of metals in soil on the organisms and is calculated using Equations (4 and 5). RI is the ecological risk index de ned as the sum of the potential ecological risk index (E i ) of various metals present in the soil [19].…”

“…The high EF value for these metals indicates the anthropogenic input of these metals in agricultural soils. The agricultural soils of east China had also shown enrichment with Cd, Pb, and Zn, which were mainly derived from anthropogenic sources [19].…”