Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity.

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29-60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95-69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24-58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2-1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Multiple trace elements exposure of Grey-cheeked Fulvettas Alcippe morrisonia, a nuclear member in bird mixed-species flocks, and implications for bioindicator.

Birds are vulnerable to metal pollution, which can serve as indicators of environmental safety monitoring. In this study, we evaluated three non-essential (Pb, Cd, and As) and two essential (Cu and Zn) trace elements of living (only feathers) and deceased (feathers and tissues) Grey-cheeked Fulvetta (Alcippe morrisonia) at a highly polluted mine tailings and a reference site. Five metal concentrations in the feathers of living Grey-cheeked Fulvettas were higher at the mine site. Among these, the levels of Cd and Pb in most feathers exceeded the threshold, resulting in an ecotoxicological concern. The correlation analysis suggested that feathers from Grey-cheeked Fulvettas might be useful bioindicators for local metal contamination assessment. The toxicological effects of trace metals on Grey-cheeked Fulvetta might affect its leadership ability. Therefore, understanding the effects of metal pollution on Grey-cheeked Fulvetta would show important practical implications for the conservation of bird communities.

Multipath diffusion process and spatial accumulation simulation of Cd in lead-zinc mining areas.

This study combined process simulation and actual measurement to construct a multipath diffusion and spatial accumulation model of Cd in a typical lead-zinc mining area through accuracy and root mean square error(RMSE) analysis. The results indicated that (1) the diffusion of Cd was in a quadratic inverse proportional relationship with the distance from the pollution source within watershed. The average annual atmospheric Cd sedimentation in study area was 0.71 * 10-6 g and the contribution of runoff diffusion to Cd exceeded 80%. (2) With the increase in the concentration range of Cd content (k) carried by unit runoff sediment, the model accuracy and RMSE showed decreasing trends. However, when the lower and upper limits of k were 10% and 90%, the model accuracy reached 75%. (3) Two sub-watersheds with same dominant wind direction but different runoff directions were selected to verify the model accuracy, indicating that the model construction method can precisely simulate the spatial accumulation of Cd in similar mining areas. The results provide a scientific basis for the prevention of heavy metal diffusion in lead-zinc mines. Future research should focus on the migration pathways of heavy metals through vertical infiltration caused by rainfall to further optimise the model structure and accuracy.

Comprehensive assessment of the microbial community structure in a typical lead-zinc mine soil.

Understanding the microbial community structure in soil contaminated with heavy metals (HMs) is a precondition to conduct bioremediation in mine soil. Samples were collected from a typical lead-zinc (Pb-Zn) mine to assess the microbial community structure of the HMs concentrated in the soil. The goal was to analyze the bacterial and fungal community structures and their interactions using the 16S rRNA genes and internal transcribed spacer high-throughput sequencing. Analyses at different sampling sites showed that contamination with HMs significantly reduced the bacterial richness and diversity but increased that of the fungi. The predominant bacteria genera of Acidobacteriales, Gaiellales, Anaerolineaceae, Sulfurifustis, and Gemmatimonadaceae, and predominant fungal genera of Sordariomycetes, Talaromyces, and Mortierella were assumed as HM resistant genera in Pb-Zn mining area. The pH effect on the bacterial and fungal communities was opposite to those of Cd, Pb, and Zn. This study offers comprehensive outlooks for bacterial and fungal community structures upon multiple HM stresses in the soil around a typical Pb-Zn mine area.

[Potential of Accumulation and Application of Dominant Plants in Lanping Lead-zinc Mine, Yunnan Province].

A field investigation in the abandoned lead-zinc mines in Yunan Province was conducted to assess the accumulation potential of dominant plant species and six heavy metals in mine soils. Eighteen types of plants were selected for the analysis. Local plants and soil were sampled and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and Zn (zinc) concentrations. Bioconcentration and translocation factors were calculated. Cluster analysis was performed to calculate the accumulation potential. The results showed that all dominant plants (18 species and 13 families) were herbaceous plants. The content of heavy metals in these plants was higher than their normal content in plants. The above-ground Cd content of Corydalis yanhusuo, Carum bretschneideri, and Picris hieracioides reached 62.29, 76.49, and 85.09 mg ·kg-1. The bioconcentration factors of Cd in these three plants were 0.57, 0.58, and 0.66, and the translocation factors were 0.89, 0.45, and 1.48, respectively. These plants have a strong ability to absorb and transfer Cd in soil; hence, they have the potential to remediate the Cd-contaminated soil. The above-ground Cd content of Euphorbia fischeriana and Cynoglossum amabile were 0.46 mg ·kg-1and 0.23 mg ·kg-1, respectively, and the bioconcentration factors were less than 0.01. These two plants accumulate low levels of heavy metals and thus, are suitable for growth in high altitude areas of Southwest China. They are considered economic plants for safe use in Cd-contaminated farmlands and have high application value. To protect the ecological environment of the mining areas, the other 13 plants having good tolerance to heavy metal pollution can be used as vegetation restoration plants in mining areas.

[Assessment of Heavy Metal Pollution in Soil and Its Bioaccumulation by Dominant Plants in a Lead-Zinc Mining Area, Nanjing].

To identify plants with potential application in phytoremediation, the concentration of cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) in soil and 14 dominant plants sampled from a lead-zinc mining area in Nanjing City was measured. Furthermore, the heavy metal contamination of soil, and bioaccumulation and translocation of the 6 heavy metals by the 14 plants were evaluated. The results showed that the principal contaminants were Cd, Mn, Zn, and Pb, and their single factor pollution index was 45.71, 11.68, 10.40, and 4.46, respectively. Furthermore, the Nemerow index of this area was 33.45, which indicated that the mining area was severely polluted. All the 14 dominant plant species were metal-tolerant, although the concentration of metal varied between different spices. Among them, Pteris multifida and Trachelospermum jasminoides significantly accumulated the heavy metals. The concentration of Zn in all the dominant plants was beyond the normal range; however, the bio-concentration factor (BCF) of only Digitaria sanguinalis for Zn was>1, while the BCF of the remaining species for the 6 heavy metals was<1. Furthermore, the heavy metal bio-transfer factor (BTF) of the 14 species was generally high. The BTF of Helianthus tuberosus and Dendranthema indicum for the 6 heavy metals was>1. According to the mechanism of heavy metal accumulation, the 14 plant species were classified into 3 types:accumulators (H. tuberosus, D. indicum, Phytolacca americana, Justicia procumbens, D. sanguinalis, Sonchus brachyotus, Solanum nigrum, and Setaria viridis), root compartment (P. multifida and T. jasminoides), and excluders (Solidago decurrens, Duchesnea indica, Carex breviculmis, and Cyrtomium fortunei).

Contaminant characteristics and environmental risk assessment of heavy metals in the paddy soils from lead (Pb)-zinc (Zn) mining areas in Guangdong Province, South China.

In November 2016, the total metal concentrations in nine representative locations in lead (Pb)-zinc (Zn) mining areas, located in Guangdong Province, South China, were determined experimentally by flame atomic absorption spectrometer. The results indicated that the paddy soils were heavily contaminated with Cd (20.25 mg kg-1), Pb (1093.03 mg kg-1), and Zn (867.0 mg kg-1), exceeding their corresponding soil quality standard values and background values. According to the results, the mean enrichment factor levels of the studied metals decreased in the following order: Cd > Zn > Pb > Cu > Ni > Mn > Cr. Among these metals, Cd, Pb, and Zn were predominantly influenced by widespread anthropogenic activities. The highest concentrations of the studied metal pollutants were distributed in the areas surrounding the mining activity district. Multivariate statistical analysis indicated that the major contributing sources of the studied metals were metal ore mining, smelting, and processing activities. However, the composition of soil background was another potential source. Moreover, the assessment results of environment risks showed that the potential ecological risks, in decreasing order, were Cd > Pb > Zn > Cu > Ni > Cr > Mn. Additionally, the non-carcinogenic risk represented the trend of HI Pb > HI Mn > HI Zn > HI Cu , and the carcinogenic risk ranked as CR Cr > CR Cd > CR Ni . Among the environmental risk substances, Cd and Pb were the main contributors that pose ecological harm and health hazards through their serious pollution. Consequently, greater attention should be paid to this situation.

The more involved in lead-zinc mining risk the less frightened: A psychological typhoon eye perspective.

In China, the current situation is that people under indirect threat from unprotected lead-zinc mining tends to oppose it, whereas people under direct threat are likely to 'sail close to the wind'. To understand this puzzle-like phenomenon, we surveyed 220 residents in a lead-zinc mining area located in Fenghuang County of China. We found that: 1) The degree of risk perception of villagers living around the mining site correlated inversely with their degree of involvement in mining risk. We refer to this as the ''involvement'' version of the psychological typhoon eye effect. 2) Perceived benefit and perceived harm provided a satisfactory explanation for this ''involvement'' version of the psychological typhoon eye effect. 3) Risk perception was negatively related to support for the relevant policy which we viewed as constituting a sort of voting behavior. The results may have implications for better understanding how benefited individuals respond to environmental health risks.