MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
artículos
Título:
Functioning of Schoenoplectus californicus (Cyperaceae) in zinc and lead contaminated sediments
Autor/es:
ARREGHINI, S; DE CABO, L.;; IORIO, A. F. DE
Revista:
SCIENCE OF THE TOTAL ENVIRONMENT
Referencias:
Año: 2006
ISSN:
0048-9697
Resumen:
Wetlands usually provide a natural mechanism to diminish the transport of toxics to other compartments of the ecosystem, immobilizing metals and store them belowground in roots and/or soil. The knowledge of metal uptake and distribution within the plant may contribute to a better understanding of these systems, ensuring that wetlands themselves will not eventually become sources of metal contamination to surrounding areas. This study investigated the ability of a population of Schoenoplectus californicus to tolerate and accumulate lead and zinc in tissues, taking into account metal distribution in sediment fractions. Plants of S. californicus were growth in sediment with Zn and/or Pb amending. Zn and Pb were mainly found in available (exchangeable) and potentially available (bound to organic matter) forms, respectively. The absorption of Zn and Pb in the plant increased with increasing sediment metal concentrations, suggesting that tissue concentrations reflect availability of these metals in the sediments. Both metals accumulated by S. californicusSchoenoplectus californicus to tolerate and accumulate lead and zinc in tissues, taking into account metal distribution in sediment fractions. Plants of S. californicus were growth in sediment with Zn and/or Pb amending. Zn and Pb were mainly found in available (exchangeable) and potentially available (bound to organic matter) forms, respectively. The absorption of Zn and Pb in the plant increased with increasing sediment metal concentrations, suggesting that tissue concentrations reflect availability of these metals in the sediments. Both metals accumulated by S. californicusS. californicus were growth in sediment with Zn and/or Pb amending. Zn and Pb were mainly found in available (exchangeable) and potentially available (bound to organic matter) forms, respectively. The absorption of Zn and Pb in the plant increased with increasing sediment metal concentrations, suggesting that tissue concentrations reflect availability of these metals in the sediments. Both metals accumulated by S. californicusS. californicus were largely retained in roots, as shown by general translocation factor (TF) values < 1. Zn root concentration was similar or higher than exchangeable Zn concentration in sediment and Pb root concentration was similar to Pb concentration in OM fraction. Pb root concentrations increased with increasing sediment metal concentrations, irrespective of Zn addition, but the concentration of Pb in rhizomes increased only in treatments with high doses of metal, associated with the restricted intake in organisms of non-essential metals. The addition of Zn increased significantly its concentration in roots while concentration in rhizomes increased only when both metals were added together. Although the addition of Zn increased its concentration in shoots, these concentrations did not reach the toxic level estimated for plants. plants. Our results point to a tolerance strategy in the presence of high metal concentrations in sediment, was reflected by the reduction of TF in treatments with metal addition. Although Zn and Pb concentration levels in roots were high, they were not sufficient to reduce biomass growth. Comparing this results with those founded in another population of S. californicus, which accumulated 14-times higher Zn concentration shoots and showed poor growth at similar Zn concentration in sediments, we could say that plants in the current study presented a different tolerance, based on a strategy of metal exclusion from aerial biomass. This finding indicates that it is necessary to select a tolerant population prior to its use in constructed wetlands for restoration or mitigation purposes. plants. Our results point to a tolerance strategy in the presence of high metal concentrations in sediment, was reflected by the reduction of TF in treatments with metal addition. Although Zn and Pb concentration levels in roots were high, they were not sufficient to reduce biomass growth. Comparing this results with those founded in another population of S. californicus, which accumulated 14-times higher Zn concentration shoots and showed poor growth at similar Zn concentration in sediments, we could say that plants in the current study presented a different tolerance, based on a strategy of metal exclusion from aerial biomass. This finding indicates that it is necessary to select a tolerant population prior to its use in constructed wetlands for restoration or mitigation purposes.