The ecophysiological adaptations of water hyacinth (metal hyperaccumulator) under adverse environmental conditions are not yet clearly elucidated. This work evaluated photosynthetic pigments and chlorophyll a fluorescence in water hyacinth plants sampled in different regions (upper, middle and lower) of Paraíba do Sul river (PSR) and Imbé river, Brazil. Additionally Mn, Fe, Zn, Cu, Cr, Pb and Ni were quantified on the shoots and roots. Roots were the preferential site of metal accumulation. Cromium was not detected in the shoots. Iron and Mn were the elements detected in higher concentrations in all samples. Zinc and Cu were detected in higher concentrations in roots of plants from middle and upper PSR, sites of higher anthropogenic activity. The highest concentrations of almost all metals were verified in plants from middle PSR. Regarding photosynthetic adaptations, plants from middle and upper PSR showed the highest concentrations of photosynthetic pigments, as well as the highest values of F v /F m and F v /F 0 . The photosynthetic performance of plants suggests that they are not under stress conditions, even in regions of higher anthropogenic activity. Positive correlation was observed among nonphotochemical quenching and carotenoids, suggesting dissipation of energy in the form of heat as an strategy to keep the stable photochemical photosynthesis functioning, confirmed by values of the F v /F m . It is possible that such adaptative strategy is efficient as a long term response to stress factors, once literature data suggest that this is not a preferential path for photosynthesis in stress circumstances under short time controlled conditions. Key-words: pollution, Paraíba do Sul river, energy dissipation, photosynthetic pigments, nonphotochemical quenchings. resuMoAs adaptações ecofisiológicas de aguapé (hiperacumuladora de metais) sob condições ambientais adversas ainda não estão totalmente elucidadas. Este trabalho avaliou pigmentos fotossintéticos e fluorescência da clorofila a em aguapé coletados em diferentes regiões (alto, médio e baixo) do rio Paraíba do Sul (RPS) e no rio Imbé, Brasil. Adicionalmente Mn, Fe, Zn, Cu, Pb e Ni foram quantificados na parte área e raízes. Ferro e Mn foram os elementos detectados em maiores concentrações em todas as amostras. Zinco e Cu foram detectados em maiores concentrações nas raízes de plantas do médio e alto RPS, locais de grande atividade antropogênica. As mais elevadas concentrações de quase todos os metais foram verificadas nas plantas do médio RPS. Com relação às adaptações fotossintéticas, plantas do médio e alto RPS mostraram as maiores concentrações de pigmentos fotossintéticos, assim como os mais elevados valores de F v /F m e F v /F 0 . As avaliações fotossintéticas destas plantas sugerem que elas não estejam sob condições de estresse, mesmo nas regiões de grande atividade antropogênica. Correlação positiva foi observada entre quenching não-fotoquímico e carotenóides, sugerindo que a dissipação de energia na forma de calor seja uma estratégia para ...
In this work, the structural and ecophysiological alterations (chlorophyll a
ResumoEste trabalho avaliou as variações espaciais e temporais na concentração de metais (Fe, Mn, Cu, Zn, Ni, Cr e Pb) em aguapé [Eichhornia crassipes (Mart.) Solms)] (raiz e parte aérea), no material particulado aderido às raízes do aguapé e no sedimento na região do baixo, médio e alto rio Paraíba do Sul (RPS) e rio Imbé, ambos no sudeste brasileiro. As amostras foram coletadas no período chuvoso e seco de 2006. Ferro e Mn foram os elementos encontrados em maiores concentrações em todos os compartimentos de ambos os rios. Nas plantas, o sítio preferencial de acúmulo de todos os metais foram as raízes. As concentrações de metais em aguapé sugerem que os metais na forma bioassimilável tendem a estar mais disponíveis na estação seca no baixo e médio RPS, provavelmente devido à menor concentração de material particulado em suspensão. Entretanto, nos demais locais analisados não houve variação temporal. As diferentes matrizes analisadas mostraram uma variação espacial de metais no RPS, provavelmente devido a particularidades geoquímicas e antropogências de cada região. O RPS apresentou altas concentrações de Cu, Zn, Ni, Cr e Pb quando comparado com o rio Imbé, em especial a região do médio RPS, mas menores concentrações do que outros rios reconhecidamente poluídos do mundo. Cu, Zn, Ni, Cr e Pb) in water hyacinths [Eichhornia crassipes (Mart.) Solms)] (root and leaves), the particulate material adhering to their roots and the sediment along the Paraíba do Sul River (PSR -high, medium and low) and Imbé River, both in southeastern Brazil. Samples were collected in 2006 at the rainy and dry seasons. Iron and Mn showed the highest concentrations in all samples for both rivers. Roots presented the highest concentrations for all metals. Metal concentrations in the water hyacinths suggest that in the dry season, particularly in the low and medium PSR, metals were more easily bioassimilated, probably due to geochemical and anthropogenic particularities of each region. Overall, PSR presented high contents of metals Cu, Zn, Ni, Cr and Pb compared to the Imbé River, but lower concentrations than those admittedly polluted rivers around the world.
The watershed of a large tropical coastal lagoon, historically hosting large sugarcane crops, which has been reduced during the last decades. It suggests that land use and land cover changes (LULCC) would lower the trophic state of the coastal lagoon due to less fertilization application and consequently reducing nutrient transfer into the lagoon. In this context, this study assessed the influence of LULCC, represented by the reduction of the sugarcane crops on the trophic state of a large tropical coastal lagoon. This influence was assessed by means of information about the long-term overall mass-balance budget, involving the estimation of the N and P loads from the sugarcane crops, other anthropogenic sources and natural processes; measurements of the river N and P fluxes into the lagoon; its seaward outflow and the long-term lacustrine nutrient retention. The results indicate that sugarcane crop reduction represented a decrease of 686 t of N and 51 t of P being emitted to the lagoon watershed. However, N and P loads from sugarcane crops were partially replaced by other anthropogenic activities, but even with the reduction of the nutrient fluxes, the long-term supereutrophic responses of the coastal lagoon was maintained. The sediment-related C/N and isotopic composition of the lagoon was sensitive to LULCC, indicating changes on the organic matter inputs into the lagoon. The trophic state was also influenced by the soil N and P accumulation and the long-term nutrient retention within the lagoon imposed by its restricted water connection to the sea.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.