Mutual Interactions between Roots of Salt Marsh Plants and Sediments and Their Relevance for Toxicity Endpoints and Rhizoremediation;pp. 103-127
Authors: (C. Marisa R. Almeida, Ana P. Mucha, Pedro N. Carvalho, M. Clara Basto, M. Teresa S. D. Vasconcelos, CIMAR / CIIMAR – Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Porto, Portugal, and others)
Abstract: The biogeochemistry at the rhizosphere of salt marsh plants only recently has started being thoroughly investigated. Knowledge on the subject is relevant to realize the potentialities of those plants for rhizoremediation (biological remediation that takes advantage of the synergy between vegetation and rhizosphere microorganisms). Roots and microorganisms living in the root zone and growing on the root exudates, can act as an independent subsystem in the sediment, which is called the rhizosphere. The concentrations of oxygen, carbon dioxide, organic matter and speciation and concentration of trace chemical species are different at the rhizosphere and surrounding sediment and condition the pH and redox potential. In the ambit of a project on this topic, targeting different salt marsh plants (Halimione portulacoides, Juncus maritimus and Scirpus maritimus) which colonize estuarine sediments in Cávado, Douro and Sado Portuguese Rivers, the role vegetation plays on distribution and remediation of trace metals, organochlorine pesticides and butyltin compounds has been surveyed. Studies in situ, ex situ and in vitro have been carried out. Attention has been also paid to the influence on the biological response of plants, of metal complexing exudates and possible synergistic or antagonistic effects of different pollutants concomitantly present at the rhizosphere. A summary of the results obtained so far by our research team is presented in this chapter.