Solid-phase partitioning and release-retention mechanisms of copper, lead, zinc and arsenic in soils impacted by artisanal and small-scale gold mining (ASGM) activities.

摘要: Artisanal and small-scale gold mining (ASGM) operations are major contributors to the Philippines' annual (Au) output (at least 60%). Unfortunately, these ASGM activities lacked adequate tailings management strategies, so contamination of environment is prevalent. In this study, soil with copper (Cu), lead (Pb), zinc (Zn) arsenic (As) due in Nabunturan, Davao de Oro, Philippines was investigated. The results showed that ASGM-impacted soils had Cu, Pb, Zn As up 3.6, 83, 73 68 times higher than background levels, respectively were classified as 'extremely' polluted (CD = 30-228; PLI = 5.5-34.8). Minerals typically found porphyry copper-gold ores like pyrite, chalcopyrite, malachite, galena, sphalerite goethite identified by XRD SEM-EDS analyses. Furthermore, sequential extraction indicate substantial Cu (up 90%), Pb 50%), 65%) 48%) partitioned strongly adsorbed, weak acid soluble, reducible oxidisable fractions, which considered 'geochemically mobile' phases environment. Although very high soils, they relatively immobile under oxidising conditions around pH 8.5 because their retention via adsorption hydrous ferric oxides (HFOs), montmorillonite kaolinite. contrast, release from historic site samples exceeded environmental limits for Class A C effluents, could be attributed removal calcite dolomite weathering. enhanced desorption at also likely contributed its soils.