Degraded mangroves as sources of trace elements to aquatic environments. (August 2022) - Queiroz, Hermano Melo
Abstract: Mangrove forests have been reported as sinks for metals because of the immobilization of these elements in their soils. However, climate change may alter the functioning of these ecosystems. We aimed to assess the geochemical dynamics of Mn, Cu, and Zn in the soils of a mangrove forest dead by an extreme weather event in southeastern Brazil. Soil samples were collected from dead and live mangroves adjacent to each other. The physicochemical parameters (total organic carbon, redox potential, and pH), total metal content, particle size, and metal partitioning were determined. Distinct changes in the soil geochemical environment (establishment of suboxic conditions) and a considerable loss of fine particles was caused by the death of the mangroves. Our results also showed a loss of up to 93 % of metals from soil. This study highlights the paradoxical role of mangroves as potential metal sources in the face of climate change. Graphical abstract: Unlabelled Image Highlights: Death of mangrove forests causes more oxidizing soil conditions. Death of mangrove trees leads to loss of fine soil particles. Dead mangrove forests lose up to 90 % of metals from its soils. Extreme weather events may shift mangrove forests into metal sources.