Chelate-assisted phytoextraction of lead from contaminated soils

Citation
Em. Cooper et al., Chelate-assisted phytoextraction of lead from contaminated soils, J ENVIR Q, 28(6), 1999, pp. 1709-1719
Citations number
24
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ENVIRONMENTAL QUALITY
ISSN journal
00472425 → ACNP
Volume
28
Issue
6
Year of publication
1999
Pages
1709 - 1719
Database
ISI
SICI code
0047-2425(199911/12)28:6<1709:CPOLFC>2.0.ZU;2-R
Abstract
Phytoextraction, a remediation strategy for lead (Pb)-contaminated soils th at removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. We evaluated Pb desorption from four contaminated s oils (total Ph 1278-14 349 mg kg(-1)) by seven chelates (CDTA, DTPA, EDDHA, EGTA, HEDTA, HEIDA, and NTA) at three rates (0.2, 2.0, and 20 mmol chelate ks soil(-1)). The three most effective chelates (CDTA, DTPA, and HEDTA) we re used in greenhouse studies with an uncontaminated soil and a Pb-contamin ated soil (total Pb = 3212 mg kg(-1)) to determine the effect of chelate ty pe and rate on growth, Pb uptake, and plant elemental composition. Lead des orption varied with chelate and soil and increased with chelate rate, avera ging 948 mg Pb kg(-1) at the 20 mmol kg(-1) rate vs. 28 mg Pb kg(-1) by the control. The general ranking of chelate effectiveness, based on total Pb d esorbed, was HEDTA > CDTA > DTPA > EGTA > HEIDA > EDDHA similar to NTA. Pla nt uptake of Pb from the contaminated soil was enhanced by CDTA, DTPA, and HEDTA, but with even the most effective treatment (corn, high CDTA rate), t he amount of Pb extracted by plants was rather low (0.4 kg Pb ha(-1)). Lead extractable by the Toxicity Characteristic Leaching Procedure) (TCLP) was increased from 9 mg L-1 in the control to from 47 to 174 mg L-1 in soils tr eated with 20 mmol kg(-1) CDTA or DTPA and chelates generally caused a shif t in Pb from resistant to more soluble chemical fractions.