Figure 1From: The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifera)Map, showing locations of sampling sites (23A13, F625, F343), sewage disposal beds, extent of historically sewage-contaminated groundwater (Ref. 32), the hydraulic gradient direction in June 2003 (middle arrow), and, for comparison, extremes in hydraulic gradient direction measured between 1987 and 2003.Back to article page