Efeitos da salinidade no acúmulo de metais pesados e nas características anatômicas, fisiológicas e bioquímicas em plantas do manguezal

• Autor(a) principal: Campos, Caroline Quenupe
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/10433
• topic: Stress; Climate change; Bioaccumulation; Bioacumulação; Estresse; Rhizophora mangle; Agronomia; Manguezais; Laguncularia racemosa; Plantas do manguezal; Salinidade; Mudanças climáticas; 57

The mangroves are coastal ecosystems frequently exposed to the pollution by heavy metals, which accumulate in sediments at high level content. It is known that the bioavailability and toxicity by such metals in the sediment is modified by the salinity, pH, soil organic matter, and other factors. According to the Intergovernmental Panel on Climate Change (IPCC), there is a forecasting of decreasing in precipitation with a consequent increasing of the salinity in tropical regions. Despite of the relevance of this theme, few is known about the morphological, anatomical, physiological and biochemical mechanisms of mangrove species in metal accumulation under different environmental conditions. The accumulation of metals in plant tissues is determined by the bioavailability of such elements in the sediment and by the efficiency of the plant absorption and translocation of such metals in root and vascular tissues. In this context, the present study has the objective of evaluate the effect of different levels of salinity on the accumulation of Chrome, Arsenio, Mercury, Lead; and into the anatomical, physiological and biochemical traits of Laguncularia racemosa (L.) Gaertn. e Rhizophora mangle L. Thus, propagules of L. racemosa and R. mangle were cultivated during to 16 months in a vegetation green-house and afterwards exposed to modified Hoagland and Arnon (1950) solutions, containing three distinct NaCl concentration (3, 7 and 11 g L-1 ) with addition of 28 µg L-1 of Cr2O7, 2 µg L-1 of As2O3, 10 µg L-1 of HgCl2 and 10 µg L-1 of PbCl2. The outcomes were statistically analyzed by the Tukey test in 5% of significance; the multivariate factorial analysis (FA); the linear discriminant analysis; and the Spearman correlation test. We performed the following analysis: 1) quantification of Chrome, Arsenio, Mercury and Lead in leaves, stem and roots; 2) determination of the factor of translocation; 3) leaf anatomy; gas exchanges; and 4) APX, CAT and SOD enzyme activity. The results show that R. mangle traits is more affected by salinity than L. racemosa, exhibiting a negative correlation to CAT activity, As stem content, and translocation factor of As (stem/root). Moreover, the results show a positive correlation between salinity and the Hg translocation factor (shoot/root). However, L. racemosa show a higher sensitivity to the heavy metal concentration, mainly to the Chrome, Arsenio and Mercury presence in roots. Those metals positively influenced the stomatal density and conductance, and the vascular bundle area from the central vein. The results also indicated that, under a more saline condition, there is a higher absorption of Cr, Pb, As e Hg in L. racemosa. Whereas higher concentrations of Cr and Hg were observed in R. mangle under lower salinity conditions. The results highlight that L. racemosa and R. mangle exhibit distinct anatomical, physiological and biochemical responses to the different levels of salinity evaluated, and to the bioaccumulation of Cr, Pb, As and Hg, as well.