Extraction of Lead and Cadmium from Soils by Cysteine and Glutathione
Metal-thiol complexes can enhance metal uptake by plant roots and microorganisms, therefore it is important to determine whether thiols effectively solubilize these metals from the soil matrix. Extractions were conducted by combining 1 g contaminated soil and 10 mL of 10 mmol L–1 thiol solution and...
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Published in | Journal of environmental quality Vol. 38; no. 6; pp. 2245 - 2252 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Madison
American Society of Agronomy, Crop Science Society of America, Soil Science Society
01.11.2009
American Society of Agronomy |
Subjects | |
Online Access | Get full text |
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Summary: | Metal-thiol complexes can enhance metal uptake by plant roots and microorganisms, therefore it is important to determine whether thiols effectively solubilize these metals from the soil matrix. Extractions were conducted by combining 1 g contaminated soil and 10 mL of 10 mmol L–1 thiol solution and shaking for 1 h. Both cysteine and glutathione extracted between 5 and 45% of Pb and Cd from laboratory and field-contaminated soils at pHs > 6 after 1 h. In the presence of oxygen, the half-life of reduced cysteine was on the order of 0.1 h and dissolved metal concentrations decreased to nearly zero over 24 h. In extractions with glutathione, both the metals and thiol were more stable, with a half-life for glutathione of 23 h, and stable dissolved metal concentrations over 24 h in the presence of oxygen. In cysteine extractions, Pb was primarily removed from the Fe/Mn oxide fraction of the amended soil and dissolved Fe concentrations followed dissolved Pb concentrations, whereas this pool of Pb was unavailable to thiol extraction in aged field contaminated soils. Iron is hypothesized to play a role in the oxidation of cysteine via both reductive dissolution of iron oxides and in the photolytic oxidation of the Fe-thiol complex in the aqueous phase. While overall cysteine was more effective than glutathione at extracting Pb from soils, its propensity to oxidize may limit its ability to increase the bioavailability of this metal to plants or microorganisms in oxic environments. |
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Bibliography: | http://dx.doi.org/10.2134/jeq2008.0524 All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 0047-2425 1537-2537 |
DOI: | 10.2134/jeq2008.0524 |