Heavy metal bioavailability and chelate mobilization efficiency in an assisted phytoextraction process.
The heavy metal bioavailable fraction of a soil is a core parameter to verify the potential risks of contaminant exposure to organisms or plants. The purpose of the present work is to identify the bioavailable metal fraction in soils treated with chelates. This fraction was evaluated directly by analyzing metal concentrations in soil solution and indirectly using sequential extraction procedures. The metal bioavailable fraction was compared with metal accumulated in plant leaves, grown in both untreated and chelate-treated reactors. In order to verify the effect of the readily and slowly biodegradable chelates [S,S]-ethylenediaminedisuccinic acid (EDDS), methylglycine diacetic acid (MGDA), and ethylenediaminetetraacetic acid (EDTA) on metal speciation in soils, a simulation of chelate treatment was made and metal concentrations in different soil compartments before and after the simulation were compared. Lead concentration in the soil solution was positively correlated with metal concentration in the test plants. The soluble fraction showed the best correlation with metal concentration in soil solution. The simulation of the chelate treatment demonstrated that EDTA and EDDS were able to extract part of the organic- and sulfide-bound fraction, which are less available to plants.
Cao
Alessia
A
DIGITA, Department of Geoengineering and Environmental Technologies, University of Cagliari, Piazza d'Armi, Cagliari 09123, Italy.
Cappai
Giovanna
G
Carucci
Alessandra
A
Lai
Tiziana
T
D000085:Acetates / Q000737:chemistry*; D001673:Biodegradation, Environmental; D002614:Chelating Agents / Q000737:chemistry*; D005029:Ethylenediamines / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry / Q000378:metabolism*; D039282:Mirabilis / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D013386:Succinates / Q000737:chemistry
D000085:Acetates; D002614:Chelating Agents; D005029:Ethylenediamines; D019216:Metals, Heavy; D012989:Soil Pollutants; D013386:Succinates; C041447:N,N'-ethylenediamine disuccinic acid