Mangroves and associated vegetation under Metals and arsenic lingering impact: the legacies of zinc smelter industry residues and iron ore in southeast Brazil

Vinicius Tavares Kutter^1*Ingrid Tavares Costa¹Alina Criane Pires¹Maria Montes-Bayon²Alfredo Sanz-Medel²Cristiane Pereira de Oliveira³Wilson Machado⁴Emmanoel Vieira Silva-Filho⁴

• ¹Federal University of Pará, Belém, Brazil
• ²University of Oviedo, Oviedo, Asturias, Spain
• ³Federal institute of roraima, Boa Vista, Brazil
• ⁴Fluminense Federal University, Niterói, Rio de Janeiro, Brazil

Mangrove forests play a crucial role in the biogeochemical cycling of trace elements in intertropical coastal regions. This study evaluated the metals and arsenic concentrations in mangrove plants and ferns (leaves, flowers and branches and root) along a tidal creek chronically affected by elevated loadings of zinc smelter industry residues and a tidal creek influenced by iron ore storage (Sepetiba Bay, Brazil). Since phytochelatins can mitigate adverse physiological effects to these plants, selected samples were analyzed for the occurrence of proteins like phytochelatins. The total element contents (As, Zn, Cd, Cr, Cu, Mn, Fe, Ni, and Pb) were determined by ICP-MS and the determination of proteins like phytochelatins was carried out by SEC-HPLC-ICP-MS. A high concentration of As (average of 34.81 mg kg-1) was detected in the fern leaves, with proteins like phytochelatins demonstrating the occurrence of two different chemical species of As in these plants, while three chemical species were found in the leaves and other two in the flowers and branches of mangrove trees. Statistical comparisons between sites showed significant differences in Cr, Cu, and Pb concentrations in leaves and Pb in branches from the Arapucaia Channel, compared to Saco do Engenho Creek. . The higher values of Cr, Cu, Pb in leaf and Pb in branches of mangrove from Arapucaia Channel can be attributed to domestic untreated effluent discharge from Mazomba River and effluent from the ore and coal Itaguaí port. The results indicate a dilution gradient from all metals (except Fe) from the former Cia Mercantil Ingá waste site to the bay. While the Arapucaia channel does not present this metal dilution pattern.