Distribution Characteristics, Source Analysis and Potential Ecological Risk Assessment of Soil Heavy Metals in Typical River Source Areas of Northeastern Hunan Province

Abstract

Soil environmental quality in water source areas related to the residents' life, health and safety, has been the hotspot issues in science of ecological environment protection. A total of 87 surface soil samples were collected from typical river source areas in northeastern Hunan Province, using GIS technique and potential ecological risk assessment index to study the spatial distribution characteristics and Potential ecological risk of soil heavy metals (Cd, Pb, Cr, Hg and As), and the means of multivariate statistical analysis and positive definite matrix factor analysis models (PMF) were used to explain the possible sources and its contribution rates of heavy metals. The results show that:① The soil located in the typical river source area of northeastern Hunan Province was acidic, and the meant of ω(Cd), ω(Pb), ω(Cr), ω(Hg), and ω(As) in soil was 0.20, 41.07, 130.51, 0.29, and 11.63mg·kg-1, respectively. And except As, all of them had enrichment tendency. ② The comprehensive potential ecological risk of soil heavy metals was at a medium level, among which Cr, Pb and As were at a slight level of potential ecological risk, and Cd and Hg all reached a strong level of risk. ③ Cd and Pb of soil had significant homology, which were derived from agricultural activity, Cr and As of soil were affected by both domestic waste discharge and natural parent material, and Hg of soil was mainly derived from fossil combustion and transportation. ④ There were four pollution sources which included household waste discharge source, natural parent material source, Fossil burning and transportation sources, as well as sources of agricultural activities in typical river source area in northeastern Hunan Province, which contributed the rates of heavy metals were 21.36%, 35.92%, 19.30% and 23.42%, respectively, and the contribution rate of man-made sources was higher than that of natural sources. To sum up, this study has reference value for pollution prevention, ecological restoration and beautiful village construction in river source area of northeastern Hunan Province.