Phytoremediation of Organic and Mineral Soils Contaminated with Multiple Trace Elements.

Trace element (TE) contamination is a common problem at industrial sites.  These sites often contain several contaminants whose varying properties make remediation efforts complex.  Phytoremediation using plant species which can accumulate multiple contaminants is a promising remediation strategy because it is inexpensive and can be performed in situ.  The overall objective of this study was to examine a multi-stage phytoremediation approach which initially targeted readily available TEs and subsequently used the chelating agent ethylenediaminetetraacetic acid (EDTA) to enhance the phytoextraction of lead and other sparingly available TEs in organic and mineral soils.  A growth room study was carried out to study the germination and early growth of three Brassica species (B. juncea, B. carinata, and B. napus) as well as the native grass Deschampsia caespitosa in contaminated mineral and organic soils and in uncontaminated soil.  A second experiment examined the effects of soil type, fertilizer, and EDTA on the uptake of TEs by D. caespitosa.  Results from the germination study showed that emergence was delayed for all Brassica species in the contaminated organic soil although percent germination was not significantly different between species in the different soils.  Both contaminated soils were associated with stunted growth of all Brassica species.  In contrast, percent germination of D. caespitosa was highest in the contaminated organic soil.  Stunted growth for D. caespitosa was seen in the contaminated mineral soil. Results from the second experiment will also be presented. These results will be useful in developing effective phytoremediation strategies for mineral and organic soils contaminated with a mixture of trace elements.