ABSTRACT
In highly industrialized estuaries, there is also a large input of heavy metals, which are accumulated in salt marsh sediments. These high inputs make salt marshes key zones for the biogeochemistry of the estuary, but also for metal cycling. When accumulated in salt marsh sediments, metals can become adsorbed to the sediment constituents and taken up by plant roots and translocated to above-ground plant organs. This plant metal uptake is a very important factor in estuarine remediation. Halimione portulacoides and Spartina maritima are two of the more abundant species in the Mediterranean salt marshes. Plants are known to exudate by their roots low-molecular-weight organic acids (LMWOA) to scavenge metallic elements important for their metabolism and/or in other cases to maintain these metallic elements outside their tissues to avoid toxicity cases. This work explores LMWOA’s natural interaction with metallic ions and how they can in¬uence the phytoremediation potential of these two halophytes. Two trials are addressed in this chapter, starting in an hydroponic greenhouse trial to test the potential enhancement of the pytoremediation process using H. portulacoides, assisted by citric acid addition. Another assisted phytoremediation trial intended to scale up the hydroponic trial to more —eld realistic conditions. In this trial intact cores of S. maritima individuals and sediments were added with several LMWOA. With this experiment became evident that with the addition of citric or acetic acid the phytoremediation potential of this halophyte can be greatly increased. Both these trial showed that assisted phytoremediation is a promising technique for enhancing the remediative process in contaminated salt marshes.
