Spatiotemporal mapping of chemical and physical fluxes at the river–ocean transition zone

Abstract

The proposed study characterizes the flow of chemical and physical fluxes on the river-ocean boundary, which is among the most significant ecological boundaries, as freshwater supplied by rivers and ocean water come together. These nutrient fluxes are crucial to the well-being of the ecosystem, the management of water quality, and curbing environmental degradation. This has significantly improved, but high-resolution data and the necessity of integrating real-time monitoring technologies to capture the variability of such fluxes is necessitated because of issues such as the river discharge, tidal cycles and human activities. The research utilized field sampling, in situ sensors, remote sensors and GIS to quantify the time and spatial distribution of the parameters such as salinity, nutrient levels, and dissolved oxygen. The results point out that there are significant differences in the fluxes among the sites with the river-mouth regions having higher nutrient and particulate fluxes compared to the nutrient-depleted coastal lands. As an example, River Mouth 1 had the maximum nitrate flux (6.2 µmol/m²/s) and Coastal Ocean 1 the lowest (1.8 µmol/m²/s). The optimal model performance was observed in River Mouth 1 (RMSE = 0.18, R2 = 0.85) and the poor performance in Coastal Ocean 1 (RMSE = 0.45, R2 = 0.72). The results establish the importance of understanding the forces in transitional regions to improve coastal management, predict the environmental changes and shape sustainable policy. This paper recommends that there is a need to enhance real time data integration as well as the need to enhance predictive models so as to manage superior river-ocean systems and ecosystems.