Oxidative Dissolution of Sulfide Minerals Tends to Accumulate More Dissolved Heavy Metals in Deep Seawater Environments than in Shallow Seawater Environments.

Deep-sea mining magnifies the release of heavy metals into seawater through oxidative dissolution of seafloor massive sulfide (SMS). At present, there is little information about how the metals released into seawater might be affected by the mineral assemblages, seawater conditions, and solid percentages. Here, leaching experiments were carried out to examine the behavior of three sulfides from the Southwest Indian Ridge, under conditions that replicated deep and shallow seawater environments at three solid-liquid ratios. The results demonstrated that sphalerite dissolved rapidly, and the metals released in both experimental conditions were comparable, potentially reflecting galvanic interactions between the sulfide minerals. Large quantities of the released metals were removed from the solutions when hydrous ferric oxides formed, especially for shallow seawater conditions. A comparison of metal concentrations in the leachates with the baseline metal concentrations in natural seawater indicated that most of the released metals, when diluted with seawater, would not have widespread impacts on ecosystems. Based on the obtained unique oxidative dissolution properties of each SMS at variable solid-liquid ratios, targeted wastewater discharge treatments are proposed to minimize impacts from the dissolved metals. This study will support the development of robust guidelines for deep-sea mining activities.

Transformation of minerals and mobility of heavy metals during oxidative weathering of seafloor massive sulfide and their environmental significance.

Seafloor massive sulfide (SMS) deposits have received widespread attention because of their potential as available metal resources. Deep-sea mining operations significantly increase the exposure of fresh sulfide to oxygenated seawater. Knowledge about mineral transformation and the fate of heavy metals during sulfide oxidation remains insufficient, which is unfavorable for eco-friendly deep-sea mining. Here, a series of partially or completely oxidized sulfide samples collected from the Yuhuang hydrothermal field, Southwest Indian Ridge, were examined for detailed mineralogical, geochemical, and morphological analyses. Models for mineral conversion and heavy metal mobility over time were established through the obtained results to assess the potential environmental impacts associated with deep-sea mining. The absence of hydrous ferric sulfates in the pure oxide samples suggests that they were transformed into iron (oxy)hydroxides after long-term exposure in seawater. There are also indications that amorphous iron (oxy)hydroxides dehydrated to layer-like goethite and that schwertmannite hydrolyzed to globular goethite. The microorganism-related morphology of secondary minerals strengthens the case that sulfide oxidation is a microbially mediated process. The enrichment of Cu, Zn, V, and U in oxidation products indicates that they can serve as effective purification agents to retain heavy metals originated from sulfide and seawater. Heavy metal contents display a progressively increasing trend in the oxide profiles, which can be well explained by our models for oxide crust accumulation. Because secondary minerals have excellent adsorption capability and mineral transformation is a reaction removal of sulfate radicals, we conclude that sulfide oxidation provides a sink for oceanic heavy metal cycles and a sulfur source in balancing the global biogeochemical sulfur cycle. In addition, mining SMS deposits containing a large quantity of Fe-bearing sulfide minerals or iron oxides from inactive hydrothermal fields are conducive to reducing environmental hazards and maintaining the economic value of remaining deposits.

The prevalence and risk factors of potentially inappropriate medication use in older Chinese inpatients with multimorbidity and polypharmacy: a cross-sectional study.

BACKGROUND: Multimorbidity and polypharmacy are common problems among the older population globally. They not only reduce the quality of life of older adults but also increase the prevalence of potentially inappropriate medication (PIM) use. This study aimed to examine the prevalence and the predictors of PIMs in hospitalized geriatric patients with multimorbidity and polypharmacy in Chengdu based on the 2015 American Geriatric Society Beers Criteria (2015 AGS Beers Criteria) and 2019 American Geriatric Society Beers Criteria (2019 AGS Beers Criteria). METHODS: From 2016 to 2018, a cross-sectional study was conducted using electronic medical data from nine tertiary hospitals in Chengdu. The 2019 and 2015 AGS Beers Criteria were used to evaluate the PIM status of older inpatients (age ≥65 years), and logistic regression was used to identify the risk factors for PIM use. RESULTS: A total of 17,352 inpatients were included in the study between 2016 and 2018. The prevalence of PIM use based on the 2019 AGS Beers Criteria (72.54%) was slightly higher than that based on the 2015 AGS Beers Criteria (70.10%). Further, the prevalence of PIM use based on the 2019 AGS Beers Criteria showed an increasing trend, from 71.17% in 2016 to 73.39% in 2018. Logistic regression demonstrated that female, advanced age, and polypharmacy were positively associated with PIM use in older adults. The most frequently used PIMs in the inpatients were diuretics, benzodiazepines, non-steroidal anti-inflammatory drugs, antipsychotics, and selective serotonin reuptake inhibitors. CONCLUSIONS: There is a high prevalence of PIM use in older inpatients with multimorbidity and polypharmacy in Chengdu. The 2019 AGS Beers Criteria is more sensitive for evaluating older adults in Chengdu than the 2015 AGS Beers Criteria. Further, based on the 2019 AGS Beers Criteria, the prevalence of PIM use is increasing year by year. Research on interventions rationing PIM use in the geriatric population in Chengdu are necessary in the future.

Deep high-temperature hydrothermal circulation in a detachment faulting system on the ultra-slow spreading ridge.

Coupled magmatic and tectonic activity plays an important role in high-temperature hydrothermal circulation at mid-ocean ridges. The circulation patterns for such systems have been elucidated by microearthquakes and geochemical data over a broad spectrum of spreading rates, but such data have not been generally available for ultra-slow spreading ridges. Here we report new geophysical and fluid geochemical data for high-temperature active hydrothermal venting at Dragon Horn area (49.7°E) on the Southwest Indian Ridge. Twin detachment faults penetrating to the depth of 13 ± 2 km below the seafloor were identified based on the microearthquakes. The geochemical composition of the hydrothermal fluids suggests a long reaction path involving both mafic and ultramafic lithologies. Combined with numerical simulations, our results demonstrate that these hydrothermal fluids could circulate ~ 6 km deeper than the Moho boundary and to much greater depths than those at Trans-Atlantic Geotraverse and Logachev-1 hydrothermal fields on the Mid-Atlantic Ridge.

Melting of recycled ancient crust responsible for the Gutenberg discontinuity.

A discontinuity in the seismic velocity associated with the lithosphere-asthenosphere interface, known as the Gutenberg discontinuity, is enigmatic in its origin. While partial mantle melts are frequently suggested to explain this discontinuity, it is not well known which factors critically regulate the melt production. Here, we report geochemical evidence showing that the melt fractions in the lithosphere-asthenosphere boundary were enhanced not only by accumulation of compacted carbonated melts related to recycled ancient marine sediments, but also by partial melting of a pyroxene-rich mantle domain related to the recycled oceanic eclogite/pyroxenites. This conclusion is derived from the first set of Mg isotope data for a suite of young petit-spot basalts erupted on the northwest Pacific plate, where a clearly defined Gutenberg discontinuity exists. Our results reveal a specific linkage between the Gutenberg discontinuity beneath the normal oceanic regions and the recycling of ancient subducted crust and carbonate through the deep Earth.

Synthesis, Characterization, and Biological Evaluations of 1,3,5-Triazine Derivatives of Metformin Cyclization with Berberine and Magnolol in the Presence of Sodium Methylate.

The novel target products were synthesized in the formation of a triazine ring from berberine, magnolol, and metformin catalyzed by sodium methylate. The structures of products 1-3 were firstly confirmed by extensive spectroscopic analyses and single-crystal X-ray diffraction. The crystal structures of the target product 2 and the intermediate product 7b were reported for the first time. All target products were evaluated for their anti-inflammatory and antidiabetic activities against INS-1 and RAW264.1 cells in vitro and all products showed excellent anti-inflammatory effects and anti-insulin resistance effects. Our studies indicated that new compounds 1-3 were found to be active against inflammation and insulin resistance.