Impact of Metal Accumulation on Photosynthetic Pigments, Carbon Assimilation, and Oxidative Metabolism in Mangroves Affected by the Fundāo Dam Tailings Plume

Abstract

The effects of iron, manganese, zinc, copper, and lead on the chlorophyll content, carbon assimilation, and the antiradical activity of Rhizophora mangle and Laguncularia racemosa were evaluated in regions affected by the Fundão dam disruption in Brazil. The mine waste which settled and accumulated in the sediments could represent long-term contamination. It can be expected that the iron oxyhydroxides deposited in the sediments will be solubilized, leading to chronic contamination by trace metals and the accumulation of these metals in the biota. In this sense, biological indicators prove to be important tools to assess this type of damage. The different bioaccumulation of metals by the species revealed that R. mangle was more impacted by Mn and Cu and that L. racemosa showed alterations in its physiological responses in the presence of Cu, Zn, and Fe. The concentration of these metals in the leaves, with values above previous local reference limits, was associated with reductions in the chlorophyll-a and chlorophyll-b content and carbon assimilation, mainly in L. racemosa. The antiradical activity was also altered, suggesting a lower ability of both species to eliminate reactive oxygen species (ROS). A possible reason for the symptoms of oxidative stress may be due to the reduced efficiency of antioxidant defense by Cu2+ and Zn2+. In addition, the presence of Pb in the leaf tissue may be toxic to the fauna and the bioaccumulation of this metal and trace elements can be a way to transfer them into the food web by biomagnification.

Ecophysiological response of Populus alba L. to multiple stress factors during the revitalisation of coal fly ash lagoons at different stages of weathering

“…The exposure of P. alba to oxidative stress at L11 is also indicated by the decrease in the Chl a + b/Tot Carot ratio compared to L3, which occurs because of the accumulation of leaf tissue damage and progressive tissue aging due to its prolonged exposure to environmental stresses ( Stoeva and Bineva, 2003 ). This is unlike the Chl a/b ratio as an early warning indicator of the toxic effects of metal accumulation in plants ( D’Addazio et al., 2023 ), which remains unchanged compared to L3. These results are in line with earlier research that also showed a decrease in chlorophyll and carotenoid content, as well as an increase in MDA in poplars in response to drought ( Kim et al., 2022 ) and heavy metal stress ( Chandra and Kang, 2016 ).…”

Impact of Particulate Matter (PM10 and PM2.5) from a Thermoelectric Power Plant on Morpho-Functional Traits of Rhizophora mangle L. Leaves

“…Additionally, a lower chlorophyll content may produce a decrease in photosynthesis, biomass production, net primary production, and even affect gross primary production in the long term [47,48]. D'Addazio [49] pointed out that, although metal uptake by mangrove trees translates into short-term bioremediation, the long-term decrease in carbon uptake and primary productivity may reduce or outweigh ecosystem services provided by mangrove forests, including metal uptake.…”