Mobilisation of AS and trace metals in saline, acidic Sopolic Technosols: the role of the rhizosphere and flooding conditions

Purpose The aim of this work was to study the risk of As and metal pollution in saline wetlands affected by slightly acidic mine wastes, in the presence or absence of a plant rhizosphere, under different flooding regimes. Some guide lines for management will be proposed in order to minimise the risk of metal leaching in metal-polluted salt marshes. Materials and methods A microcosm experiment was conducted to assess the influence of two flooding regimes (continuous or alternating) and the presence of rhizosphere (Sarcocornia fruticosa and Phragmites australis) on the mobilisation of As, Cd, Mn, Pb, Zn and Fe in a slightly acidic, saline Spolic Technosol (pH≈6.5; total concentrations:551 mg kg−1 As, 5,640 mg kg−1 Pb, 5,299 mg kg−1 Zn). Results and discussion Metal and As pore water concen trations decreased with flooding time (e.g. from approxi mately 1,700 μg L−1 Cd, 190 mg L−1 Zn and 230 mg L−1 Mn to <400 μg L−1 Cd, <35 mg L−1 Zn, and 50 mg L−1 Mn). A sequential extraction showed that Fe and As were associated mainly with the silicate fraction of the soil, but most of the Mn, Cd, Pb and Zn belonged to the reactive fraction. The rhizosphere of Sarcocornia induced a lower pH, which facilitated higher concentrations of soluble Fe. However, in pots without plants and pots with Phragmites, the combination of Eh and pH led to conditions for formation of siderite, and hence the concentrations of soluble Fe were lower. The concentrations of Mn, Cd, Pb and Zn were lower in vegetated pots, probably due to precipitation of metal carbonates favoured by gas exchange in the rhizosphere. Conclusions The rhizosphere modified soil conditions during the period of flooding and this affected the dynamics of metals. The high levels of soluble metals pose a risk for leaching, transfer to the food web and toxicity for living organisms. In order to reduce the risks, we propose the water saturation of the soil and the establishments of a plant cover.

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Cervantes A.M. Conesa H.M. González Alcaraz M.N. y Álvarez Rogel J. Mobilisation of AS and trace metals in saline acidic Sopolic Technosols: the role of the rhizosphere and flooding conditions. Springer Nature, 2011. https://doi.org/10.1007/s11368-011-0361-4

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Resource type Article
Date of creation 2024-11-05
Date of last revision 2025-01-20
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Metadata identifier 1707170a-ee00-5c41-9a29-81f3e20bf7a1
Metadata language Spanish
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High-value dataset category Earth observation and environment
ISO 19115 topic category biota
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Name of the dataset creator Cervantes, A.M. Conesa, H.M., González Alcaraz, M.N. y Álvarez Rogel, J.
Name of the dataset editor Springer Nature
Other identifier DOI: 10.1007/s11368-011-0361-4
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Email of the dataset creator jose.alvarez@upct.es
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