Distribution and bioaccumulation of potentially toxic metals in water, sediments, and algal biomass of Santa Catarina Dam

Abstract

The Santa Catarina Dam (SCD) functions as a hydrological regulation system and a provider of key ecosystem services in Querétaro, a Mexican city that has endured rapid urbanization and industrial growth in recent decades. These pressures have increased the vulnerability of the SCD to anthropogenic pollution. In this study, an environmental assessment of the reservoir's pollution status was conducted, combining physicochemical parameters of water quality, potentially toxic metals and elements (PTME) in the water, sediment, and algal biomass. The results show an impact on water quality based on the values ​determined for COD, BOD₅, dissolved oxygen, turbidity, total nitrogen, and total phosphorus, which exceeded the limits established by national and international guidelines. The Overall Index Pollution (OIP) shows that the SCD water is in the range of slightly contaminated to contaminated. In sediments, the Enrichment Factor (EF) values reported a severe enrichment for Li, Zn, Pb, V, Cu, and Sr, suggesting a relevant contribution from industrial activities. The PTME levels in the algal biomass showed a high bioaccumulation of Fe, Mn, Si, Cu, Ni, and Li, according to the Bioaccumulation Factor (BF) values. Principal component analysis (PCA) shows a contribution from anthropogenic and natural sources on the water and sediment quality of the SCD. These findings support the implementation of long-term monitoring of priority contaminants, such as PTME and nutrients, as well as strengthened industrial and agricultural management to prevent further degradation of the SCD.