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Metal budgeting

Geochemical estimates of metal bioavailability, Bioaccumulation by aquatic macrophytes and microphytes

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Organisms as biomonitors

Metal bioaccumulation, Biochemical monitors of metal bioavailability

FIGURE 24.1 Processes responsible for biogeochemical cycling of metals from sediments to interstitial waters.

FIGURE 24.1 Processes responsible for biogeochemical cycling of metals from sediments to interstitial waters.

FIGURE 24.2 Biotic and abiotic factors regulating the metal bioavailability in sediments.

Dissolved organic carbon Humic and fulvic acids M-organic

M-inorganic anions

FIGURE 24.3 Trace metals in natural waters exist in different oxidation states or forms complexed or bound to inorganic and organic matter and the distribution of these forms is often referred to as the speciation.

metal are more available and toxic than others. This fact has been recognized in recent environmental legislation relating to surface water quality, e.g., for copper, aluminum, and silver [16]. As a consequence, industry and environmental regulators require an increasing amount of information on metal speciation.

Microbial activity and animal activity (bioturbation) releasing bound metals [18]; exchange of ions between rhizosphere and metals partitioned in interstitial waters [18] (Figure 24.3 and Figure 24.4)

Once released into the interstitial water, metals become available in the waters of upper surface and thus facilitate the process of bioconcentration. In wetland ecosystems, physicochemical and biological processes operate that provide a suitable situation for removal of metals [19]. It is clear that development of a rational, effective, and economic strategy to remediate contaminated sedi-

Vesicular, arbuscular ectomycorrhiza (ECM)

Extra matrical mycelia metal binding sites adsorb toxic metals

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Hyp fil

hal mantle of ECM act as ter or barrier for metals on the root surface

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