Spatio-temporal dynamics of arsenic and its relationship with physicochemical parameters in the Tampamachoco lagoon, Veracruz, Mexico

Coastal lagoons are commonly regarded as critical sinks for hazardous chemical agents (HCAs) due to their unique hydrodynamics and significant anthropogenic pressures. Among these agents, arsenic (As) is of particular concern due to its environmental persistence, high toxicity, and ability to mimic essential elements like phosphorus (P) in cellular processes, making it a highly polluting agent and a multisystemic disruptor. In estuarine-lagoon systems such as Tampamachoco, the environmental kinetics of As are considered high, as they depend on physicochemical variables that influence speciation and bioavailability, posing a risk to food security and public health. This study analyzed the spatio-temporal dynamics of this metalloid and its correlation with physicochemical parameters including pH, salinity, temperature, dissolved oxygen, electrical conductivity, and total dissolved solids over an annual cycle from January to December 2025. The dry season (June and August) yielded the highest peak concentrations of As (0.013 mg/L and 0.018 mg/L, respectively), in contrast to the cold fronts and rainy seasons. Although the reported concentrations did not exceed the maximum permissible limits established by Mexican regulatory frameworks (NOM-001-SEMARNAT-2021) of 0.1 mg/L, low inverse correlations were observed with electrical conductivity (ρ=-0.386), salinity (ρ=-0.276), and total dissolved solids (ρ=-0.381), alongside a low positive correlation with temperature (ρ=0.326). These data suggest that As does not follow the general ionic load of the matrix; rather, its presence appears to be governed by temperature-dependent processes rather than evaporation or salt concentration mechanisms.