Chemical characterization as a baseline for watershed management, Drake Bay

Abstract

The article provides a baseline of scientific knowledge on quantified ions in freshwater bodies, in particular five rivers in the Drake Bay area; data to understand at a macro level the risks and vulnerabilities of the ecosystem, as well as to generate alerts in the protection of water resources. A total of 84 representative samples from the Drake, Agujitas, Claro, Llorona and Sierpe rivers were analyzed in three intensive sampling campaigns (two during the summer season and one in winter, corresponding to the years 2019 and 2020). The dissolved ions of chlorides, sulfates, calcium, sodium, magnesium, potassium, zinc, lead, cadmium, copper, arsenic, manganese and mercury were determined; to be used as indicators of environmental quality and human health. The results allow us to highlight that the excess anion concentration comes mainly from the impact of agricultural activity in the study area, a situation that is more evident in the Drake, Llorona and Agujitas rivers, compared to the Claro and Sierpe rivers; However, all the rivers studied present ionic concentrations that allow them to be classified from the chemical point of view, as healthy rivers with an acceptable quality, once they have been compared with the applicable national regulations. On the other hand, the rainy season improves the ionic chemical balance of the salts dissolved in the water, thanks to the dilution factor and the oxidation capacity of the organic mass load that transits over the rivers. Finally, there is no evidence of dissolved heavy metals that favor bioaccumulation processes in the aquatic ecosystems under study.