Tropical Subterranean Estuaries and Their Role in Nutrient and Metal Inputs to the Ocean

Matt Charette and Meagan Gonneea, Department of Marine Chemistry and Geochemistry, WHOI

Non-point sources of pollution like submarine groundwater discharge represent a significant, yet poorly quantified threat to the ecology of coastal systems throughout the world. Tropical systems may be particularly endangered due to the ongoing and future shifts in land use and coastal management practices. Pollutants such as macronutrients and trace metals must traverse subterranean estuaries, the zone where fresh ground water mixes with intruding salt water, before discharging into the ocean. There is a growing body of literature suggesting that biogeochemical transformations within subterranean estuaries play a significant role in modulating material fluxes to the coastal ocean, however, they remain largely unexplored, particularly in tropical regions. We propose to study the geochemistry of trace metals and nutrients in geologically contrasting tropical subterranean estuaries: one in western Panama (Liquid Jungle Lab), and another on the Yucatan Peninsula of Mexico. This exploratory research will allow us to gain insight into the workings of tropical subterranean estuaries, which in turn will provide key information on an important endmember for global fluxes of nutrients and metals from coastal groundwater systems.