Hydrochemical monitoring of rivers in the Bocas del Toro region of Panama: insights into impacts on coastal environments

Abstract:

The chemical composition of river waters can be used to understand biogeochemical processes occurring in watersheds and to help predict the response of coastal environments to freshwater inflows. Despite advancements in empirical and process-based models, accurately simulating the temporal dynamics and fine spatial variability of river chemistry remains a challenge. Data at these scales are critical, however, to addressing a variety of research and environmental problems. So, time-series sampling remains a necessary, but challenging approach for characterizing many river systems, especially in the tropics.

Here, we report on-going times-series measurements of river discharge and hydrochemistry from rivers in the Bocas del Toro region of Panama and apply them to understanding solute budgets of the Almirante Bay. Our dataset includes 6 rivers with variable catchment areas (6 to 3123 km²) and landcover attributes (e.g., population density, slope, ecosystem type) sampled every two weeks. Assuming an absence of evaporite deposits, which is supported by regional geologic mapping, differences in riverine chloride concentrations imply spatial variations in evapo-transpiration fluxes, which will be further tested using water isotopic measurements. Using dissolved Si data for all of the rivers as well as marine waters, we will construct a Si budget for Almirante Bay to help elucidate the origins of seasonal hypoxia and the role of Si bio-mineralizing organisms.