Avaliação de metais pesados na samambaia Amauropelta rivularioides (Fee), no solo e na água de rio em uma área de agricultura periurbana na fronteira Brasil–Paraguai

Abstract

This study investigated environmental contamination by metals in soils, surface waters, and in the fern Amauropelta rivularioides (Fée) in the peri-urban area of the Santa Virgem River, in Ponta Porã (MS), Brazil, between 2019 and 2020. Samples were collected in five distinct periods of the agricultural calendar. The soils showed high concentrations of As (up to 5.9 mg/kg), Se (7.9 mg/kg), Co (14.9 mg/kg), Mn (524.6 mg/kg), Cu (13.8 mg/kg), and Zn (above 7.0 mg/kg), exceeding reference values from the United States Environmental Protection Agency and the state of Pará. A. rivularioides demonstrated significant bioaccumulation, especially for As (53.9 mg/kg), Pb (74.8 mg/kg), Cr (98.0 mg/kg), and Ba (up to 80 mg/kg in some periods), reflecting the direct transfer of contaminants from the soil to plant tissues. Surface waters showed metal concentrations below the detection limit, but phosphorus occurred at very high levels (up to 5.52 × 10⁶ in the Risk Coefficient), indicating a risk of eutrophication. Environmental indices indicated moderate to very high pollution: the Contamination Factor for As reached 1,762, for Mn 2.93, and for P above 325, with a Pollution Load Index > 1 in all periods. The health risk analysis revealed a Risk Coefficient and Hazard Index far above 1, characterizing chronic risk, while the Incremental Lifetime Cancer Risk values ranged from 0.0159 to 0.0180, indicating significant carcinogenic risk, especially from dermal exposure to As, Pb, and Cr. The results show that intensive agricultural management contributes to soil contamination and bioaccumulation in native vegetation, posing environmental and public health risks. It is concluded that A. rivularioides is an effective bioindicator of metal pollution in agricultural border environments and that monitoring and mitigation measures should be implemented.