Fig. 3: Vertical profiles of groundwater and clay pore water properties.
From: Arsenic contamination of Bangladesh aquifers exacerbated by clay layers
A generic site litholog is displayed on the right with shading in the panels indicating the extent of major clay/silt layers encountered. a Water levels are the annual average (December 2012–November 2013) groundwater elevations in meters above sea level. b Tritium (3H) concentrations and d Oxygen-18 isotopic composition in water (δ18O) are one-time measurements with analytical error bars smaller than the symbol size. c Tritium-helium (3H/3He) ages were corrected for radiogenic He contribution and degassing at the time of sampling, where necessary; error bars indicate propagated analytical errors or standard deviations of the ages determined under different assumptions, whichever error is greater. e Arsenic, f iron, and h chloride concentrations in groundwater were averaged from discrete samples collected in 2011–2012 (arsenic data through 2016/17 from well nest M-Middle are shown in Fig. 1b); at depths where >3 samples were measured, standard deviations are also shown (As and Fe); Cl standard deviations are smaller than the symbol size. g Dissolved organic carbon concentrations.
