Decrease of labile Zn and Cd in the rhizosphere of hyperaccumulating Thlaspi caerulescens with time.
By using a rhizobox micro-suction cup technique we studied in-situ mobilization and complexation of Zn and Cd in the rhizosphere of non-hyperaccumulating Thlaspi perfoliatum and two different Thlaspi caerulescens ecotypes, one of them hyperaccumulating Zn, the other Zn and Cd. The dynamic fraction (free metal ions and small labile complexes) of Zn and Cd decreased with time in the rhizosphere solution of the respective hyperaccumulating T. caerulescens ecotypes, and at the end of the experiment, it was significantly smaller than in the other treatments. Furthermore, the rhizosphere solutions of the T. caerulescens ecotypes exhibited a higher UV absorptivity than the solution of the T. perfoliatum rhizosphere and the plant-free soil. Based on our findings we suggest that mobile and labile metal-dissolved soil organic matter complexes play a key role in the rapid replenishment of available metal pools in the rhizosphere of hyperaccumulating T. caerulescens ecotypes, postulated earlier.
Dessureault-Rompré
Jacynthe
J
Institute of Terrestrial Ecosystems (ITES), ETH Zurich, Universitätstrasse 16, CH-8092 Zürich, Switzerland. dessureaultromj@agr.gc.ca
Luster
Jörg
J
Schulin
Rainer
R
Tercier-Waeber
Mary-Lou
ML
Nowack
Bernd
B
D001673:Biodegradation, Environmental; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism; D007854:Lead / Q000032:analysis* / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D031227:Thlaspi / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead