GEOCHEMICAL AND MINERALOGICAL ANALYSIS OF CAVE DEPOSITS TO RECONSTRUCT CLIMATE CHANGE IN BARBADOS FOR WATER RESOURCE MANAGEMENT

Water resources in island nations are under the threat of climate change impacts, including drought, flooding, and sea-level rise, and on islands comprised of karst terrain, freshwater aquifers are exploited out of necessity. The island of Barbados depends on groundwater for 90% of its drinking water supply to serve the increasing demands of tourism, agriculture, and native populations. Understanding the potential implications of changes in climate on the groundwater resources is of utmost importance, and few records exist that provide a long-term view of past climate change, and thus future cycles of possible precipitation or drought patterns. A single stalagmite was selected from Harrison’s Cave in Barbados, and through trace element (TE) analysis of strontium, calcium, and magnesium, as well as Scanning Electron Microscope (SEM) and Raman spectroscopy for mineralogical analysis, and fluorescence analysis to detect organic content variability, the reconstruction of precipitation variability and calcite deposition from rock weathering patterns were generated over the Late Holocene (past 1,500 years). Changes in the mineralogy indicate cyclic periods of lamina deposition likely resulting from changes in rainfall and rock weathering. Raman spectral analysis shows a recent period of increased Mg substitution, which may result from changes in groundwater recharge and land use. SEM data indicate detrital layers, which were indicative of changes in dripwater variability and calcite deposition. Differences in the Ca/Mg amounts and fluorescence in the layering provides information on variable weathering related to climatic variability. These physical proxy analysis data provide additional information over the period of deposition to supplement more traditional stable isotope data to better understand climate change cycles and impacts on groundwater recharge in the region. This information is invaluable to the inhabitants of Barbados because the island is isolated and the primary source of water comes from an aquifer that has been significantly depleted in recent years. An understanding of natural shifts in precipitation variability and its influence on recharging groundwater resources, will allow those living on the island to prepare for future changes.