Antimony (Sb) and arsenic (As) are two hazardous metalloid elements, and the biogeochemical cycle of Sb and As can be better understood by studying plant rhizosphere microorganisms associated with Sb mine waste. In the current study, samples of three types of mine waste—Sb mine tailing, waste rocks, and smelting slag—and associated rhizosphere microorganisms of adapted plants were collected from Qinglong Sb mine, southwest China. 16S rRNA was sequenced and used to study the composition of the mine waste microbial community. The most abundant phylum in all samples was Proteobacteria, followed by Bacteroidota, Acidobacteriota, and Actinobacteriota. The community composition varied among different mine waste types. Gammaproteobacteria was the most abundant microorganism in tailings, Actinobacteria was mainly distributed in waste rock, and Saccharimonadia, Acidobacteriae, and Ktedonobacteria were mainly present in slag. At the family level, the vast majority of Hydrogenophilaceae were found in tailings, Ktedonobacteraceae, Chthoniobacteraceae, and Acidobacteriaceae (Subgroup 1) were mostly found in slag, and Pseudomonadaceae and Micrococcaceae were mainly found in waste rock. Actinobacteriota and Arthrobacter are important taxa for reducing heavy metal(loid) mobility, vegetation restoration, and self-sustaining ecosystem construction on antimony mine waste. The high concentrations of Sb and As reduce microbial diversity.

The Givetian Age witnessed the greatest expansion of stromatoporoid-coral reefs from low to higher latitudes of the Phanerozoic. Multi-proxy seawater surface temperature reconstruction suggests the establishment of a super-greenhouse climate as a major reason for reef expansion, yet many questions remain. This article presents the results of a rare earth element and yttrium (herein referred to as REY, derived from REE + Y) geochemical study as well as mineralogy and oxygen isotope values of two well-documented Middle Givetian reefal carbonate sections (Jiwozhai and Buzhai) of the Jiwozhai Formation of South China. The nearshore Jiwozhai patch reef succession displays greater biodiversity and more abundant coral than the marginal platform Upper Buzhai reef. Reefal and micritic carbonates of the Jiwozhai section are characterized by shale-like post-Archean Australian Shale (PAAS)-normalized REY patterns, by very weak negative Ce anomaly values (Ce/Ce* 0.80–0.96; average = 0.89), slightly elevated Y/Ho values (28.9–39.1; average = 34.1), and near-unity values of (Pr/Yb)N (average = 0.87), (Pr/Tb)N (average = 0.80), and (Tb/Yb)N (average = 1.09). Moreover, REY patterns of deposits of the Jiwozhai section differ markedly from those of modern seawater. The described geochemical aspects of the Jiwozhai section and the positive correlation of REY and Th contents displayed by the section point to a terrestrial siliciclastic contribution contemporaneous with reef-building. In contrast, REY patterns of the Upper Buzhai reef section samples are similar to those of modern seawater characterized by light rare earth element (LREE) depletion (average (Pr/Yb)N = 0.76), negative Ce anomalies (average Ce/Ce* = 0.88), and average super-chondritic Y/Ho ratios (average = 45.4)). Slightly positive Eu anomalies (Eu/Eu* = 0.93–1.94; average = 1.36) of the Upper Buzhai reef section samples are attributed to the negligible effect of hydrothermal fluids. Middle REE (MREE) enrichment (average (Tb/Yb)N = 1.48) of Buzhai section carbonate samples and positive correlation of REY and Th suggest a riverine input. Combined with siliciclastic mineralogy, oxygen isotope values, and reef-building biota morphology of the studied two sections, we suggest that terrestrial nutrients delivered by rivers far outweighed upwelling as a source of nutrients supplied to the Givetian reef ecosystem of South China. Coral and stromatoporoid in tropic oceans thrived in turbid water containing abundant terrestrial sediment and the nutrient-laden water helped expand reef-builder habitats during the Givetian time.

Heavy metal pollution derived from the oxidation of sulfides in Pb-Zn mine tailings has been a common public concern. Although the oxidative dissolution of sphalerite will release cadmium into the soil environment, it is still unclear whether other minerals contain a large amount of cadmium and how much these minerals contribute to the surrounding environmental media. In this paper, XRD, particle size analyzer, SEM-EDS and improved BCR sequential extraction method were used to analyze cadmium rich zinc mine tailing and adjacent farmland soil in Duyun, Guizhou Province. The results show that the average contents of Pb, Zn, and Cd in tailing are 214 ± 71 mg/kg, 2668 ± 773 mg/kg, and 37.5 ± 9.97 mg/kg respectively. While in the surrounding soil, they were 519 ± 280 mg/kg, 3,779 ± 2614 mg/kg, and 30.8 ± 14.4 mg/kg respectively. The mineralogical composition of tailing is mainly dolomite and less pyrite. Cadmium in tailing is mainly in weak acid extractable state, indicating that cadmium mainly exists in dolomite of tailing. Pyrite in tailing generates acid through oxidation, which accelerates the dissolution of dolomite, thus releasing Cd from minerals and migrating to surrounding farmland, resulting in soil cadmium pollution. This study reveals an important process that has been neglected. Carbonate minerals play an important role in the migration of cadmium in the tailing of the Mississippi Valley-type (MVT) lead-zinc mine and the soils affected by the tailing.

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