Hydrogeochemical contrasts between low and high arsenic groundwater and its implications for arsenic mobilization in shallow aquifers of the northern Yinchuan Basin, P.R. China

Hydrochemical processes in a shallow coal seam gas aquifer and its overlying stream–alluvial system: implications for recharge and inter-aquifer connectivity

“…Following recent work by Huang and Pang (2012) and Guo et al (2014), the d-excess values are presented together with TDS contents to further document the processes driving groundwater salinisation (Fig.4). Two distinctive trends can be observed in Fig.4 Fig.4).…”

Factors influencing the distribution of arsenic, fluorine and iodine in shallow groundwater in the oasis zone in the southern margin of the Tarim Basin in Xinjiang, P. R. China

“…Previous studies showed that As concentration in shallow groundwater in the Tarim Basin is related to reductive dissolution of Fe(III) oxides [6]. High TDS (ranged between 199 and 358694 mg/L, with an average of 11532 mg/L) and pH values in groundwater in the study area lead to the reduce of Ca 2+ ion activity, which inhibit the formation of CaF2 and promote the enrichment of groundwater [10]. Under weak alkaline conditions, Iadsorbed on the sediment will migrate to groundwater, which indirectly promotes the enrichment of groundwater I [11].…”

High Radionuclides in Groundwater of an Inland Basin from Northwest China: Origin and Fate

“…Groundwater usually evolves from oxic conditions to reducing conditions from alluvial fans to flat plain in those above-mentioned basins. ,, In the flat plain under reducing conditions, reductive dissolution of Fe/Mn oxides has generally been observed. ,, As a result of high affinity of Fe/Mn oxides for Ra, reductive dissolution of those solids would mobilize Ra into groundwater . In addition to dissolution, α recoil processes of Th–U series result in Ra enrichment in groundwater. , In contrast, precipitation of barite eliminates groundwater Ra as a result of relatively high concentrations of Ba and SO 4 2– , which generally balances released Ra via reductive dissolution and α recoil processes in the Hetao basin.…”

“…However, Ra adsorption may be significantly affected by redox conditions as a result of the redox sensitivity of Fe/Mn oxides with the high affinity for Ra. , Accordingly, Ra would be mobilized in reducing groundwater systems, where Fe/Mn oxides are subject to reductive dissolution. Reductive dissolution of Fe/Mn oxides has been accepted as the major mechanism of As mobilization in high As groundwater aquifers, which have been observed worldwide. − However, few data are available for Ra mobilization and geochemical processes in those aquifers hosting high As groundwater, although high concentrations of groundwater U have been documented in the recharge areas of high As groundwater. , Sources and immobilization mechanisms of Ra and Rn are poorly understood within those Quaternary aquifers.…”