Potential Ecological Risk Assessment of Heavy Metals in Cultivated Land Based on Soil Geochemical Zoning: Yishui County, North China Case Study

Linsong Yu,Kai Zang,Hongbo Liu,Zeming Shi,Xiuwen Zhang,Fugui Zhang,Ling He,Fang Wan

doi:10.3390/w13233322

Abstract

Various human production activities have caused tremendous damage to the soil ecological environment of cultivated land. Regional ecological risk assessments and the safe use of cultivated land have received widespread attention. The ecological risk assessment of heavy metals based on soil geochemical zoning has not been reported in the past. Using 14,389 topsoil samples, considering comprehensive geological background information, Yishui County in northern China was divided into three soil geochemical areas and 14 soil geochemical sub-regions by means of principal component factor superposition. The results of environmental quality and risk assessments of eight heavy metals based on soil geochemical zoning show that the single pollution index was greater than 1.0 and the Nemerow pollution index was greater than 0.7 for Ni in a sub-region, indicating that Ni pollution had reached the early warning limit, which demonstrates that Ni has a certain enrichment trend. Meanwhile, the geoaccumulation index of Ni and Cr was greater than zero in some sub-regions, indicating a slight pollution level. In addition, the potential ecological risk factor of the measured heavy metals was greater than 40 in 9 sub-regions, indicating a moderate ecological hazard, and the risk index was greater than 150 in a sub-region, revealing moderate ecological intensity, in which Hg and Cd were leading contributors to potential ecological hazards with a contribution rate between 58% and 76%. This method is suitable for the evaluation of soil environmental quality and safety for medium and large scales, and can provide a scientific basis for further zoning and grading prevention and control of soil pollution in cultivated land.

Highlights

According to a report of the National General Survey of Soil Contamination in China (2014), the total excess rate of heavy metals in soil is 16.1%, of which the proportions of slightly, lightly, moderately, and severely polluted sites were 11.2, 2.3, 1.5 and 1.1%, respectively, and the excess rates of Cd, Hg, As, Pb, Cu, Cr, Zn, and Ni were 7.0, 1.6, 2.7, 1.5, 2.1, 1.1, 0.9 and 4.8%, respectively
In this study, a method based on soil geochemical zoning was employed to assess the potential ecological risk of cultivated soil
On the basis of a geological structure background, the soil pH of cultivated land in the study area was used as the dominant variable, and three soil geochemical zones with 14 soil geochemical sub-regions were obtained by means of superimposing multi-element combination factors

Summary

Introduction

According to a report of the National General Survey of Soil Contamination in China (2014), the total excess rate of heavy metals in soil is 16.1%, of which the proportions of slightly, lightly, moderately, and severely polluted sites were 11.2, 2.3, 1.5 and 1.1%, respectively, and the excess rates of Cd, Hg, As, Pb, Cu, Cr, Zn, and Ni were 7.0, 1.6, 2.7, 1.5, 2.1, 1.1, 0.9 and 4.8%, respectively. Soil heavy metal pollution as a result of natural background and anthropogenic factors significantly affects environmental quality [1,2,3,4,5,6,7,8,9,10,11]. As, Cd and other elements, as heavy metal elements with strong toxicity in the soil environment, have strong accumulation and bioaccumulation. They can be transformed into crops through soil crops in the cultivated soil, and endanger human health through the food chain [12,13,14]. Regional ecological risk assessments and the safe utilization of cultivated land are of increasing public concern [15,16,17]

Methods

Results

Conclusion