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Mining activities are well-known sources of potentially toxic elements (PTEs) pollution, which often jeopardize the biosphere, pedosphere, and hydrosphere. However, the soil and groundwater pollution caused by active private mining activities has long been neglected. This study investigated the occurrence of PTEs and cyanide (CN) in agricultural soils, mine tailings, and groundwater nearby the cyanide baths from a private gold mine in Hainan Province, southern China. Results indicated that concentrations of Pb, As, Cd, Hg, and CN in different soil depths and mine tailings were up to ten thousand mg/kg, and relatively higher content of As and Pb was detected in groundwater. The chemical forms of Cd, Pb, As, and Hg varied greatly in different soil depths; over 80% of Cd distributed in the water-soluble fraction, suggesting its higher mobility in soils, while approximately 60–90% of Pb, As, and Hg distributed in other chemical fractions, indicating relatively lower mobility in soils. The pollution indices also revealed the serious pollution and deterioration of site quality in this area. Human risk assessments also reflected a high non-carcinogenic/carcinogenic health risk in this area. The framework of integrated management strategies for private metal mines was proposed to mitigate PTEs pollution and reduce health risks. [ABSTRACT FROM AUTHOR]

• A virtual district metering area (V-DMA) was first proposed to modularize the water supply network. • A visual analytic hierarchical process (V-AHP) was developed to identify the leakage areas. • Combination of subjective and objective weights accurately judged the actual leakage situation. • Integration of V-AHP with V-DMA revealed the high leakage areas in each V-DMA. • The specific problems existing in each V-DMA partition were revealed by the V-AHP model. Assessment and early warning of leakage risk in the water distribution network are important for securing urban sustainable development. However, the identification of high leakage areas in urban water distribution networks lacks visual model-driven approaches. In the current study, the model parameters of the water distribution network (i.e., leakage point density, pipe age and material, road load, and average pressure of the pipe network) were collected in Haidian Island, Hainan Province, China as a case. The virtual district metering area (V-DMA) was used to modularize the water distribution network. A visual analytic hierarchical process (V-AHP) based on the V-DMA was established for identifying the leakage high-risk areas in the V-DMA. The first and second-level discriminant matrices (i.e., subjective and objective weights, respectively) were calculated based on the model parameters. Integration of V-AHP with V-DMA reveals insight into high leakage areas of urban water distribution networks, which was consistent with in-situ observations. Overall, this study provides a simple, efficient, and practically applicable method for identifying the leakage areas in water distribution networks. [ABSTRACT FROM AUTHOR]

The establishment of new buffer zone in the mine areas lacks the basis of theoretical model. As a case study, this study presents the partition model of new buffer zone in a small-scale mine area located in the remote mountainous region of Hainan province, China. The investigation carried out by integration of geostatistical interpolation maps using unmanned aerial vehicle has revealed that As, Cd, Pb, Zn, and Hg are mainly distributed near the tailing ponds and the dressing plant, while Cr and Cu are prominent near the agricultural area. The partition model of buffer zone was established in accordance to the transport velocity of the liquid phase heavy metal in soil. The boundary line of buffer zone is integrated by comparing the 'predicted' heavy metal concentrations with the 'measured' heavy metal concentrations. Principal component analysis (PCA) and the variations of heavy metal concentrations with elevation, slope, and distance were performed to further evaluate the reliability of the predicted buffer zone, indicating that the new buffer zone has a significant effect on minimizing transport of heavy metals from the mining area into the agricultural land. This study is suggestive to provide risk control and sustainable development strategy for the ecosystem protection in mine areas. [Display omitted] • Unmanned aerial vehicle is used to acquire the remote sensing pictures of polluted area. • The geostatistical method is used to visualize the spatial distribution of heavy metals. • Prediction of a buffer zone has been carried out using a novel model in this field. • The reliability of the predicted buffer zone is validated. • The buffer zone has a significant effect on minimizing transport of heavy metals from mine area. [ABSTRACT FROM AUTHOR]