Geochemical Baseline Values Determination and Evaluation of Heavy Metal Contamination in Soils of Lanping Mining Valley (Yunnan Province, China)

Abstract

The largest lead/zinc mine in China is located in Lanping mining valley. The real impact of mining activity on the Lanping mining valley has not been studied to date. This study aims to characterize the geochemical baseline values and risk assessment of heavy metal contamination in soils of a study area located in the Lanping mining valley including upstream, mining and downstream areas. The results showed that the mean soil pH value was 6.8, and organic matter was 34.3%, in surface layer of the mining area. The mean soil pH value in the upstream and downstream areas was less than 5.5. The concentrations of Pb and Zn in the mining area were 56 and 47 times above the world average, the concentrations of Pb, Zn and Cd in the upstream area were six, seven, and six times above the world average, and the concentrations of Pb, Zn and Cd in the downstream area were eight, eight, and 18 times above the world average, respectively. The proposed geochemical baseline values of Pb, Cu, Zn and Cd were 169.93, 31.81, 569.06 and 4.13 mg·kg−1, respectively. The pseudo total and ethylene diamine tetraacetic acid (EDTA)-extractable concentrations of Pb, Zn and Cd showed similar tendency as follows: mining area > downstream area > upstream area. The contamination degree with the geoaccumulation index (Igeo) and the improved Nemerow index (IIN) in the upstream and mining areas was non-contamination or slight contamination with low or moderate risk with the individual ecological risk index (Er) and the comprehensive potential ecological risk index (RI), although moderate or heavy contamination with pollution factor (Pi) and the Nemerow index (IN). The contamination degree with Igeo and IIN in the downstream area was non-contamination or extreme contamination with low or extreme risk with Er and RI. The results suggest that the IIN should be recommended to assess the soil contamination of heavy metals and the geochemical baseline values would be important for the environmental management and remediation of soils contaminated by heavy metals.

Toxicity studies on sediments near hydropower plants on the Ślęza and Bystrzyca rivers, Poland, to establish their potential for use for soil enrichment

“…Calculation of toxicity indices for HMs: geochemical method (Pierwoła et al, 2020), LAWA , pollution Factor (P i ) (Kowalska et al, 2018), Nemerow index (IN) (Z. Li et al, 2019), geoaccumulation index (I geo ) (Kilunga et al, 2017;Santos-Francés et al, 2017), contamination factor (C f ) (Solgi & Parmah, 2015), ecological risk index (E r ) (M. S. Rahman et al, 2014;Hakanson, 1980), classification for each sample in the LAWA and geochemical methods (Table A1 in Appendix A), or calculations (other parameters; Table A2); final classification in Table A3.…”

Review of global trends in meeting the ecological challenges of the mining industry. Part I: International research

“…Farther from the mine, the concentration decreased but were nevertheless higher than the average global level by 6-18 times. The soil pollution evaluation used the geoaccumulation index, the ecological risk index, etc., advisable for the environment management and soil recovery control [34].…”

Assessment of trace elements natural enrichment in topsoil by some Italian case studies

“…Although referring to a Regional Geochemical Baseline Mapping is a valid procedure, it would be better to determine the local geochemical baseline, because it is more representative since the trace elements anomalous values recorded to particular sites could be geogenic [2]. In fact, to determine local geochemical baseline, its necessary sampling of topsoil at depths not exceeding 1 m of soils (subsurface horizon) [15,27,28]. The surface layers (from 0 to 20 cm) provided more information on the pollution levels caused by the geogenic processes of soil formation or anthropogenic sources.…”

“…In the hypothesis that it is not possible to carry out a subsurface soil horizon samples and the Regional Geochemical Baseline Mapping is not available, some studies [29][30][31] identify statistical methods (cumulative frequency and normalization method) as useful tools to define the geochemical baseline values. In order to assess the soil pollution status, some studies [28,[32][33][34][35][36] use some quantitative indexes: the geoaccumulation index (I geo ) and the enrichment factor (EF). By comparing the concentrations of a trace element in the topsoil and the locally natural background for the study area, these indexes allow the "health of a soil" assessment.…”