Although global mercury (Hg) emission from chlor-alkali industry is decreasing, the legacy Hg may still have potential risks due to its environmental persistence. The objective of this work is to study the biogeochemical cycling and potential risk of Hg in the Ya-Er Lake, which was heavily contaminated by historical chlor-alkali production. Higher concentrations of total Hg (THg) in Ya-Er Lake water (16.8 ± 8.4 ng L-1) and sediment (547 ± 489 ng g-1) than other lake systems were observed, reflecting serious Hg pollution in this system. Diffusion rates of Hg at sediment-water interface and budget of Hg showed that release of legacy Hg in sediment (accounting for ∼80%) dominated THg in water, and about 80% methylmercury (MeHg) of total was diffused from sediment. Significant correlations between total organic carbon (TOC) derived from aquaculture and THg diffusion and MeHg concentrations in sediment suggest that TOC plays important roles in controlling legacy Hg release and MeHg production. The actual weekly intakes of Hg via consumption of cultured catfish and wild topmouth culter were higher than the established provisional tolerable weekly intake (PTWI) of MeHg. These results indicated that although the nearby chlor-alkali plant has been shut down for three decades, the release of legacy Hg stored in the sediment still adversely affects this ecosystem. Moreover, aquaculture could enhance MeHg production and control MeHg distribution in the polluted aquatic ecosystem, potentially posing a health risk to surrounding inhabitants through consumption of fish.The mobility of contaminant metals in aqueous subsurface environments is largely controlled by their interaction with humic substances as colloidal constituents of Dissolved Organic Matter. Transport models for predicting carrier-bound migration are based on a competitive partitioning process between solid surface and colloids. However, it has been observed that dissociation of multivalent metals from humic complexes is a slow kinetic process, which is even more impeded with increasing time of contact. Based on findings obtained in isotope exchange experiments, the convoluted time dependence of dissociation was fully described by a complex two-site approach, integrating rate "constants" that are in turn time-dependent. Thus, this study presents the treatment of a particular phenomenon kinetics within kinetics. The analysis showed that the inertization process does not lead to irreversible binding. Consequently, thermodynamic concepts using equilibrium constants remain applicable in speciation and transport modeling if long time frames are appropriate.Potentially toxic elements (PTEs) generated from mining activities have affected ecological diversity and ecosystem functions around the world. Accurately assessing the long-term effects of PTEs is critical to classifying recoverable areas and proposing management strategies. Mining activities that shape geographical patterns of biodiversity in individual regions are increasingly understood, but the complex interactions on broad scales and in changing environments are still unclear. In this study, we developed a series of empirical models that simulate the changes in biodiversity and ecosystem functions in mine-affected regions along elevation gradients (1500-3600 m a.s.l) in the metal-rich Qilian Mountains (∼800 km) on the northeastern Tibetan Plateau (China). Our results confirmed the crucial role of PTEs dispersal, topography, and climatic heterogeneity in the diversification of plant community composition. On average, 54% of the changes in ecosystem functions were explained by the interactions among topography, climate, and PTEs. However, merely 30% of the changes were correlated with a single driver. The changes in species composition (explained variables = 94.8%) in the PTE-polluted habitats located in the warm and humid low-elevation deserts and grasslands were greater than those occurring in the dry alpine deserts and grasslands. The ecosystem functions (soil characteristics, nutrient migration, and plant biomass) experienced greater changes in the humid low-elevation grasslands and alpine deserts. Our results suggest that the processes driven by climate or other factors can result in high-altitude PTE-affected habitat facing greater threats.Biogas production through anaerobic mesophilic digestion is the most straightforward biofuel production route integrated into microalgae-bacteria wastewater treatment plants. Improvement of this biofuel route without adding pretreatment units is possible through the temperature increase. This paper presents a comprehensive evaluation of the transitory effect of different temperatures (35 °C and 55 °C) and hydraulic retention times (HRT) of 15 and 30 d on the long-term methane production using non-pretreated microalgae-bacteria aggregates as a feedstock. The thermophilic transition from mesophilic inoculum adapted to microalgae-bacteria aggregate increased 1.7-fold the methane production (0.41 m3CH4 kgVS-1) at HRT of 30 d. A substantial decrease in the microbial community's diversity present in the anaerobic reactor was observed when thermophilic conditions were applied, explaining the long adaptation period needed. The increase of the operative temperature condition promotes changes in the dominance pathway of methanogenesis from hydrogenotrophic to acetolactic. The energy balance assessment showed a positive net energy ratio when the digester was operated at an HRT of 30 d. A maximum net energy ratio of 1.5 was achieved at mesophilic temperature. This study demonstrated, based on experimental data, that microalgal digestion with an HRT of 30 d favors energy self-sustainability in microalgal wastewater treatment plants.Petrographic and mineralogical analyses combined with sequential extractions and leaching experiments as a function of pH were performed on black clayey sediments fulfilling karsts in the Hydrogeological Experimental Site (HES) of Poitiers (France) to investigate the behavior of arsenic and selenium in a fractured limestone aquifer. Sequential extractions showed that arsenic is mainly associated with pyrite (about 35%) and secondary iron oxyhydroxides (around 13%), along with a substantial exchangeable fraction (about 13%). The soluble fraction and the fraction associated to organic matter are ∼2% and ∼5%, respectively. The distribution of selenium is mainly pyritic (around 39%) or associated with organic matter (about 18%). Its association to secondary iron oxyhydroxides minerals is low (around 2%), whereas its soluble fraction is around 5%.  https://www.selleckchem.com/products/dinaciclib-sch727965.html  SEM analyses revealed the presence of arsenic "hot spots" into euhedral pyrite crystals surrounded by a halo of iron oxyhydroxides resulting from their alteration, and both are enriched with arsenic.