Composição química do sedimento e de folhas das espécies do manguezal do estuário do Rio São Mateus, Espírito Santo, Brasil

Abstract

-(Chemical composition of sediments and leaves of mangrove species at the São Mateus river estuary, Espírito Santo State, Brazil). We analyzed nutrient concentrations in leaves and sediments, and element accumulation capacity in foliar tissues of Avicennia germinans (L.) Stearn., Avicennia schaueriana Staft & Leechm., Laguncularia racemosa (L.) Gaertn. f. and Rhizophora mangle L. in four sites along the São Mateus River estuary mangrove, Espírito Santo State, SE-Brazil. In sediment, elements decrease following the sequence: Mg > Ca > Fe > K > Mn > P > Zn > Cu and showed inter and intraespecific variation. Avicennia leaves showed the greatest N, K and Mg concentrations and lowest Ca concentrations. Rhizophora mangle presented the greatest Mn concentration, and Laguncularia racemosa the greatest Fe level. Sediment nutrient concentrations reflected the influence of granulometry in this compartment. Nutrient accumulation in leaves varied according to species and study site but it was not correlated with sediment concentrations. Results confirmed the mangrove role as a biogeochemistry barrier blocking heavy metal up to tropical coastal areas. However, it is necessary periodic sampling so that it can be possible a better understanding of the nutrient dynamic.Key words -heavy metals, leaves, mangrove, nutrients RESUMO -(Composição química do sedimento e de folhas das espécies do manguezal do estuário do Rio São Mateus, Espírito Santo, Brasil). As concentrações de nutrientes das folhas e do sedimento e a capacidade de acumulação de elementos químicos dos tecidos foliares das espécies Avicennia germinans (L.) Stearn., Avicennia schaueriana Staft & Leechm., Laguncularia racemosa (L.) Gaertn. f. e Rhizophora mangle L. foram analisadas em quatro estações de estudo no manguezal do estuário do Rio São Mateus, no Estado do Espírito Santo. De modo geral, os elementos determinados no sedimento seguiram a ordem: Mg > Ca > Fe > K > Mn > P > Zn > Cu, apresentando variações inter e intraespecíficas. No tecido foliar, as espécies de Avicennia apresentaram maiores teores de N, K e Mg e menores concentrações de Ca. Rhizophora mangle exibiu maior concentração de Mn e Laguncularia racemosa, maior teor de Fe em relação às demais espécies. Os resultados demonstraram que a concentração de nutrientes do sedimento refletiu a influência da granulometria neste compartimento. O acúmulo de nutrientes nas folhas variou de acordo com a espécie e estação de estudo, mas não refletiu as concentrações do sedimento. Os dados confirmaram o papel do manguezal como barreira biogeoquímica ao trânsito de metais pesados. Entretanto, torna-se desejável uma amostragem periódica para um melhor entendimento da dinâmica de nutrientes.Palavras-chave -folhas, manguezal, metais pesados, nutrientes IntroduçãoO conhecimento da dinâmica e da estrutura dos ecossistemas demanda a compreensão dos teores de nutrientes, sua distribuição nas plantas e no solo, processos de ciclagem e fluxos de entrada e de saída (Hay & Lacerda 1984). A comunidade vegetal representa p...

Distribution of Cu, Fe, Mn, and Zn in Two Mangroves of Southern Brazil

“…Average values of leaf concentrations were consistent with the values described in the literature on Brazilian mangroves Bernini and Rezende 2010;Cuzzuol and Rocha 2012). The variation in the leaf concentrations observed among the studied species (Table 3) was partly due to the salt excluding condition of the Rhizophora gender species, or to the salt including condition of the Avicennia and Avicennia gender species (Lacerda et al 1985;Bernini et al 2006). Specifically, the low leaf levels of Fe, Zn and Cu in R mangle could be due to the salt exclusion mechanism, which affected the absorption of these elements (Lacerda et al 1985).…”

“…In the studied areas, the differences in Fe, Mn, Cu, and Zn concentrations in the soils, both between the species and mangroves could be related to temporal (Cuzzuol and Rocha 2012) and spatial variations, which were linked to the chemical and physical characteristics of the soil (Bernini et al 2006;. Tides variation also interfered on the availability of chemical elements (Lacerda et al 1986), resulting in a concentration/dilution effect on the nutrients of this ecosystem (Ong Che 1999).…”

“…In their study on southeastern Brazilian mangroves, Machado et al (2005) (Bernini et al 2006). In the case of Fe, in particular, beyond the above descriptions, the genetic efficiency of plants in the mechanisms involving morphological and anatomical alterations of the roots is also to be considered (Römheld andMarschner 1986, Mengel andKirkby 1987).…”

Heterogeneity of elemental composition and natural abundance of stables isotopes of C and N in soils and leaves of mangroves at their southernmost West Atlantic range

“…The N and P concentrations are within the upper range of variation in mangroves elsewhere indicating that the sediments in these mangrove sites are quite fertile as suggested also by the soil analyses (Lacerda et al, 1985;Medina et al, 2001;Bernini et al, 2006;Lugo et al, 2007;Medina et al, 2010). Besides, the N/P molar ratios are all below 30 for the mangrove species, and slightly above 30 in the associated species, well below the values reported from P-limited mangroves in the Caribbean .…”

“…These cations sequences have a wide range of variations among mangroves that are associated with the influence of marine waters. In São Matheus, Brasil (≈18ºS) Bernini et al (2006) reported K concentrations in sediments of 5.9 mmol kg -1 , well below the values obtained in our sites in Santa Catarina, and the cation sequence was Mg>Ca>K. In Bragança peninsula (Para, Brasil, ≈1ºS) K concentrations decreased towards to coast but were always higher than Ca concentrations (Medina et al 2001) The average Na/K molar ratios are larger for PA (18), followed by TA (7) and LA (2), differing markedly from the Na/K ratio of standard sea water (46). This indicates that all three sites are within a humid climate zone, rainfall counteracting Na accumulation in the superficial soil layer.…”