TRANSPORT OF DISSOLVED ORGANIC CARBON IN MOUNTAINOUS RIVERS OF DOMINICA, LESSER ANTILLES

Small mountainous rivers on high standing islands around the world provide a significant contribution to the amount of carbon that is delivered to the global ocean. Tropical mountainous regions experience high physical and chemical weathering rates caused by rapid uplift and extreme rainfall events. These result in high concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the mountain streams that is transported to the ocean. Previous studies have shown that some of the highest DOC fluxes in the world occur in small mountainous river systems such as those in New Zealand, Taiwan, and Papua New Guinea. However, very little has been done to quantify the overall carbon transport of river systems in the Caribbean and the effect that local geology and vegetation may have on DOC concentrations. Dominica is a volcanic island, with little organic carbon found in the bedrock, making it a highly suitable natural laboratory to investigate the delivery of organic carbon solely from the soils. Besides uplift and erosion from heavy rainfall, weathering rates are affected by the topography of the watersheds and characteristics of the underlying bedrock. This project investigates the DOC yields from eleven rivers in Dominica and compares the total carbon fluxes from different regions of the island to determine a possible relationship between carbon transport and underlying bedrock of the rivers. Our results show high DOC fluxes and speak to the overall importance of these volcanic islands with regards to the annual global carbon cycle.