Mobility of metals in salt marsh sediments colonised by Spartina maritima (Tagus estuary, Portugal)

Abstract

Chemical associations of Zn, Pb, Cu, Co and Cd were determined using a sequential extraction procedure in sediments colonised by S. maritima in three salt marshes within the Tagus estuary: Rosário, Corroios and Pancas. Concentrations of these metals were also analysed in above-and belowground parts of Spartina maritima, as well as in sediments colonised by the plant. The highest metal concentrations in sediments were found in the marshes near the industrial and urban areas, whereas metal concentrations in plants were not significantly different among sites. This was thought to be a consequence of differences observed in metal bioavailability: Metals in Pancas, the least polluted location, were largely associated to easily accessible fractions for plant uptake, probably as a result of low organic matter content and high sandy fraction in sediments. S. maritima was able to induce the concentration of metals between its roots in the three salt marshes. The results obtained in this study indicate that S. maritima could be useful to induce phytostabilisation of metals in sediments, although the effectiveness to modify chemical associations is highly dependent on existing sediment parameters, and thus different results could be obtained depending on site characteristics.

Halophytes as sources of metals in estuarine systems with low levels of contamination

“…Similar behaviour was noted in Z. noltii in the present work, but for the other two studied species, the aboveground biomass presented lower metal values in comparison with the belowground biomass, which is in agreement with previous studies (Duarte et al 2010). Our results showed that the heavy metal concentrations were higher in the belowground organs (in agreement with Cambrollé et al 2008;Reboreda et al 2008;Duarte et al 2010) of both S. maritimus and S. maritima, which suggests the ability to accumulate heavy metals; in contrast, Z. noltii showed similar concentration levels in both aboveground and belowground organs but still accumulated metal. The three studied species presented higher belowground biomass values in the spring than the other seasons, and many of the heavy metal concentrations were higher in autumn and winter.…”

“…When plants accumulate metals, the roots and rhizomes generally show higher concentrations than the aboveground parts (Sinicrope et al 1992). This behaviour could be seen in other studies like Reboreda et al (2008) and Duarte et al (2010). It was also confirmed that heavy metal accumulation is not strictly independent of biomass production (Caçador et al 2009;Duarte et al 2010).…”

“…Most salt marsh plants accumulate large amounts of metals in both their aerial and belowground organs (Caçador et al 2000). Salt marsh species greatly influence the inputs and outputs of metals and nutrients in the marsh (Caçador et al 2004;Reboreda and Caçador 2007;Reboreda et al 2008;Sousa et al 2008;Caçador et al 2009) owing to the different uptake rates of these elements. As the highest levels of metal accumulation are found in the root tissues (Caçador et al 2000;Reboreda and Caçador 2007), the decomposition of root litter may also be a source of metals released to the surrounding sediment through leaching (Weis and Weis 2004;Pereira et al 2007).…”

Distribuição de mercúrio total em sedimentos da plataforma continental Amazônica: Brasil

“…Além disso, o processo de transporte e deposição/sedimentação do material particulado em suspensão dependerá também de um conjunto de fatores físico-químicos, que incluem além da salinidade, o tempo de residência das águas, a baixa velocidade de fluxo de corrente, potencial redox, pH, teor de matéria orgânica, tamanho das partículas, concentração de sulfetos e presença de bactéria sulfatoredutoras (Machado 2004;Cardoso et al 2008;Reboreda et al 2008). Segundo os autores ainda, ambientes aquáticos com maior tempo de residência ou que não apresentam competência de transporte possibilitam a deposição do material particulado em suspensão no sedimento, ficando a biodisponibilidade dos metais associados controlada aos fatores físico-químicos supracitados.…”

Avaliação da dinâmica do mercúrio (Hg) na Bacia do Rio Madeira nos ambientes lêntico e lótico

“…A baixa solubilidade do Hg na água, devido ao pH, facilita a deposição dele (REBOREDA et al, 2008). O que demonstra a insignificância dessa matriz na biomagnificação ao longo da cadeia trófica aquática.…”