HR: 16:45h
AN: H24C-04 INVITED     [Abstracts]
TI: Groundwater Flow and Arsenic Biogeochemistry in Bangladesh
AU: * Harvey, C F
EM: charvey@mit.edu
AF: MIT, 48-321, Cambridge, MA 01742 United States
AB: Although groundwater in Bangladesh is severely contaminated by arsenic, little is known about the complex transient patterns of groundwater flow that flush solutes from aquifers and carry solutes into the subsurface. Hydrologic modeling results for our field site in the Munshiganj district indicate that groundwater flow is vigorous, flushing the aquifer over time-scales of decades and also introducing solute loads into the aquifer with recharge from rice fields, ponds and rivers. The combined hydrologic and biogeochemical results from our field site imply that the biogeochemistry of the aquifer system may not be in steady-state, and that the net effect of competing processes could either increase or decrease arsenic concentrations over the next decades. Modeling results suggest that irrigation has greatly changed the location, timing and chemical content of recharge to the aquifer, drawing large fluxes of anoxic water into the aquifer during the dry season that may mobilize arsenic from oxides in near-surface sediments.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1040 Isotopic composition/chemistry
DE: 1045 Low-temperature geochemistry
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting