Geochemical Evolution in the Modern Groundwater System of Barbados
This research uses major and trace element and isotopic variations in groundwater compositions to constrain the relative influences of 1) mineral-solution reactions with aquifer and aquitard rock, 2) ion exchange in soils, 3) seawater mixing, 4) anthropogenic inputs and 5) variations in amount of recharge in the karst Pleistocene limestone aquifer of Barbados in the West Indies. Major element compositions of groundwater reflect the effects of limestone dissolution and fresh groundwater-seawater mixing in coastal areas, while elevated nitrate concentrations indicate a widespread anthropogenic impact. Groundwater strontium isotopic variations are used to trace soil and rock sources of dissolved constituents. Discrete recharge takes place through sinkholes and dry valley beds, especially where permeable limestone is exposed. Soils influence recharge because of varying infiltration rates. Soils occurring at higher elevations are more permeable than those at lower elevations. Consequently, there is greater potential for diffuse recharge to take place through soils at higher elevations on the island. Recharge was quantified by mass-balance calculations and by comparison of chloride concentrations and oxygen isotopic compositions of groundwater and rainwater. The results indicate that recharge is due to rapid infiltration, occurs only during the wettest months of the year, and represents 15-25% of annual rainfall.
This research is detailed in the following publications:
Jones, I. C. and Banner, J. L., 2003, Estimating recharge thresholds in tropical karst island aquifers: Barbados, Puerto Rico and Guam, Journal of Hydrology, in press.
Jones, I. C. and Banner, J. L., 2003, Hydrogeologic and climatic influences on spatial and interannual variation of recharge to a tropical karst island aquifer, Water Resources Research, in press.
Jones,
I. C., Banner, J. L., and Humphrey, J. D., 2000, Constraining recharge in a tropical karst
aquifer. Water Resources Research 36,
1289-1299.
Temporal Evolution of Groundwater on Barbados as Recorded in Speleothems
Our studies of the modern system pose the questions: How has the composition of groundwater on Barbados changed through time? To what extent does this reflect interactions between climatic and hydrologic systems? This is addressed through geochronologic and geochemical studies of speleothems - see Banner et al. (1996) in publication list.
This research project is also critically evaluating the suitability of speleothems and proxies for paleoclimate reconstructions. This is the Ph.D. research of Patrick Mickler.
More about groundwater in urban environments
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