Spatial and temporal patterns of groundwater arsenic in shallow and deep groundwater of Yinchuan Plain, China

Groundwater is a strategic resource in Yinchuan Plain, with deep groundwater increasingly used for drinking water supply to reduce arsenic exposure of rural villagers who have relied on shallow tube wells for drinking. To understand the sources and mobilization processes for arsenic enrichment in groundwater, a well water and sediment geochemistry study was carried out. Considerable spatial variability of groundwater arsenic exists. Arsenic concentration in deeper groundwater (40–250m) was generally less than 10μg/L (n=26) except for seven wells, with a mean of 7.0μg/L (n=33). For shallower depths (4–40m), As concentration increased from