Influence of agriculture on surface water quality in three lentic environments in a conservation unit of Brazil

The use of agricultural inputs (AIs) without technical criteria can affect the quality of water sources and impact the biota present in these environments. This research sought to verify whether there was contamination in the surface water bodies of three lentic environments in a fully protected conservation unit in Brazil, called Estação Ecológica de Águas Emendadas (ESECAE), originating from agricultural activity near its perimeter. The ESECAE is the source of water bodies that flow into important hydrographic basins in Brazil and South America. Water quality parameters (WQPs) related to the use of AIs were selected and evaluated to assess compliance with regulatory provisions regarding the priority use of water at the study site. The analysis of the results revealed that in some situations, these parameters exceeded the normative limit in some samples and that, in general, the transport of contaminants originating from rainfall occurred. Total phosphorus (TP) values were high, exceeding regulatory concentration limits in multiple analyses. Consequently, eutrophication processes were verified in these environments. The eutrophic environments favored the proliferation of aquatic macrophytes, such as the invasive species Hyparrhenia rufa . TP concentrations increased during the dry season in these environments. In this context, a process related to the dynamics of phosphorus in aquatic lentic environments under certain conditions was observed. In conclusion, this research highlights the importance of monitoring WQPs in different periods to better assess water quality and to understand contaminant dynamics.