No abstract

High arsenic (As) groundwater is frequently found in inland basins, yet the contributions of different processes to aqueous As distributions remain unresolved. In the Hetao Basin, a typical inland basin, groundwater As concentrations generally increased from the alluvial fan through the transition area to the flat plain. A geochemical process‐based reactive transport model was established to evaluate and quantify the processes of As mobilization in the northwestern Hetao Basin. Thirty‐six groundwater samples and eight sediment samples were collected from the alluvial fan to the flat plain to investigate the geochemical characteristics of the groundwater system. Along the approximate flow path, groundwater evolved from oxic‐suboxic conditions to anoxic conditions, with increasing concentrations of As, Fe (II), and NH4+, and decreasing Eh and SO42−/Cl−. Modeling results indicated that the observed concentrations of Fe (II) were caused by reductive dissolution of Fe (III) oxides and subsequent precipitation of mackinawite and siderite. Reductive dissolution of Fe (III) oxides was primarily driven by organic matter degradation (>75%), followed by H2S oxidation (<25%). More As was sequestered by mackinawite precipitation and adsorption than that released via abiotic reduction of Fe (III) oxides by H2S. Reductive dissolution of Fe (III) oxides was the dominant mechanism for liberating As in both the transition area and the flat plain (>70%), and As desorption under elevated pH and competitive adsorption by HCO3− and PO43− made an important contribution to As enrichment (up to 30%). Overall, this study provides an insight into the relative contributions of different geochemical processes to As enrichment in inland basins.

No abstract

High arsenic (As) groundwater (>10 μg/L) has been increasingly observed throughout the world (Bundschuh

No abstract

The evaluation of groundwater quality plays an important part in the evaluation of groundwater resources. It analyses the temporal and spatial distributions and utilisation of underground water according to the main components and corresponding water quality standards for underground water. Thereby, it can provide a scientific basis for the development, utilisation, planning, and management of groundwater resources. Set pair analysis (SPA), based on the improved five-element connectivity degree, was used in this research to establish a comprehensive evaluation model of water quality, so as to evaluate the groundwater quality in XuChang, Henan Province, China. Meanwhile, fuzzy evaluation was also used to measure groundwater quality. As demonstrated in the research results, SPA is proven to be convenient and useful with objective and stable results, it therefore is an effective approach with which to evaluate groundwater quality. In addition, the results obtained using SPA matched those from fuzzy comprehensive evaluation; it was concluded, based on the analysis, that the groundwater in XuChang was severely polluted. The groundwater quality at the observation points located in the lower reaches is poorer than that of the upper reaches; hazardous substances permeate underground to pollute shallow groundwater through decomposition and loss due to weathering and rainfall.

No abstract

No abstract