The accuracy of environmental risk assessment depends upon selecting appropriate matrices to extract the most risk-relevant portion of contaminant(s) from the soil. Here, we applied the chelatants EDTA and tartaric acid to extract a metal-contaminated soil. Pistia stratiotes was applied as an indicator plant to measure accumulation from the metal-laden bulk solutions generated, in a hydroponic experiment lasting 15 days. Speciation modeling was used to elucidate key geo-chemical mechanisms impacting matrix and metal-specific uptake revealed by experimental work. The highest concentrations of soil-borne metals were extracted from soil by EDTA (7.4% for Cd), but their uptake and translocation to the plant were restricted due to the formation of stable metal complexes predominantly with DOC. Tartaric acid solubilized metals to a lesser extent (4.6% for Cd), but a higher proportion was plant available due to its presence mainly in the form of bivalent metal cations. The water extraction showed the lowest metal extraction (e.g., 3.9% for Cd), but the metal species behaved similarly to those extracted by tartaric acid. This study demonstrates that not all extractions are equal and that metal-specific speciation will impact accurate risk assessment in soil (water)-plant systems. In the case of EDTA, a deleterious impact on DOC leaching is an obvious drawback. As such, further work should now determine soil and not only metal-specific impacts of chelatants on the extraction of environmentally relevant portions of metal(loid)s.

• Keywords
• DOC leaching, Metal speciation modeling, Rhizofiltration, Soil chelatants, Water lettuce,
• MeSH
• Araceae * MeSH
• Biodegradation, Environmental MeSH
• Edetic Acid chemistry   MeSH
• Cadmium MeSH
• Soil Pollutants * analysis   MeSH
• Soil chemistry   MeSH
• Metals, Heavy * analysis   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Edetic Acid MeSH
• Cadmium MeSH
• Soil Pollutants * MeSH
• Soil MeSH
• tartaric acid MeSH Browser
• Metals, Heavy * MeSH