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Publication
Phytoremediation of cadmium at different salinities by Scirpus maritimus from the Óbidos Lagoon (Portugal)
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Abstract(s)
A greenhouse experiment was performed, to verify if phytoremediation of cadmium
can be done by using the macrophyte Scirpus maritimus from the Obidos Lagoon
(Portugal), plus if water salinity can influence its phytoremediation effectiveness. Two concentrations of cadmium were tested (50 and 100 ƒÊg l-1) to evaluate the plant capability to accumulate cadmium, plus possible toxicity effects of this pollutant. The contamination levels were tested at different water salinity conditions (values equal to 0.0, 5.0, 10.0 and 20.0), in which the plants are usually submerged in, at their natural environment.
S. maritimus mortality was mostly determined by the water salinity and not for the
cadmium contamination, in which more plants died at higher water salinities. The surge of
new shoots, plant length and biomass increments were not proved to be affected by either of those factors, however, plant length and reduction and biomass loss can be induced by
increasing water salinities. There was a biofilm development in all trial vessels,
independently of the type of treatment involved. These suspended microorganisms and
senescent organic matter presented more cadmium, according to initial water level of
cadmium. The amount of water dissolved cadmium was positively related to the initial
contamination levels of the experiment, but it increased also at higher water salinities. This may have resulted from tissue degradation and disruption from dead plants, possibly
potentiated as well by symbiotic organisms and those from the biofilm, some of which may
have promoted tissue decomposition and bioavailability of dissolved cadmium. The plants presented more cadmium in the rhizomes, followed by the stems, and less in the leaves.
More cadmium accumulated in the plant fs rhizomes, according to higher water
contamination levels and lower water salinities. According to the results, salinity could influence the transport of cadmium in the plant, between roots and leaves.
However, the phytoremediation of the Obidos Lagoon by S. maritimus, or other similar systems, may be not be possible, due to the salt stress of the plants, the salt
interference with the cadmium accumulation, and the normal functions of a plant. But the
optimization of phytoremediation processes by S. maritimus could turn possible the use of this plant in freshwater ecosystems.
Description
Dissertação de Mestrado em Biotecnologia dos Recursos Marinhos apresentada à ESTM - Escola Superior de Turismo e Tecnologia do Mar do Instituto Politécnico de Leiria
Keywords
Bioremediation Accumulator plant Heavy metal Halophyte plant Absorption atomic spectrometry Salt marsh