Spatial characteristics of heavy metal pollution and the potential ecological risk of a typical mining area: A case study in China

摘要

The goal of the presented research was to evaluate the possible heavy metal pollution in soil by applying Hakanson risk evaluation method with adjusting assessment domain combined with ArcGIS technology. The assessment standards were adjusted based on the amount and types of studied heavy metals. Topsoil samples in mining area were collected and tested the content of five kinds of heavy metals, Arsenic (As), mercury (Hg), copper (Cu), lead (Pb) and zinc (Zn). The area of different risk levels and the area ratio in each township were accurately calculate, and the regions with high pollution risk were further precisely located. The results indicate the following: (1) It was observed that the accuracy of soil-heavy metal assessment in Suxian was evidently improved by using Hakanson potential ecological risk with assessment domain adjustment. (2) The single factor and Nemero pollution indexes showed an evident contamination of five types of heavy metals in Suxian. (3) There is a high index of comprehensive ecological risk in Suxian; approximately 82.9% of Suxian is at a strong (level 3 or higher) risk level, demonstrating serious soil pollution. The quite strong risk region with,the portion of 18.33% of total area is primarily concentrated in the area of the large Polymetallic mine and coal mining area. Using the single factor ecological risk index, the distribution of large areas of As and Pb high-risk pollution were explored. More than half of the soil in Suxian presents a strong Hg (level 3 and higher) risk level, and the primary strong ecological risk and quite strong ecological risk townships were identified as well. (4) A more finely characterized pollution status was achieved from this pollution assessment in Suxian based on the township level, rendering the study results a more practical guide and increasing their significance. (C) 2017 The Authors. Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.