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Evaluation of Chloropyromorphite Stability in the Rhizosphere of Brassica juncea and Medicago sativa in a Sand Culture
Author(s) -
Abbaspour Ali,
Arocena Joselito M.
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0062
Subject(s) - rhizosphere , brassica , dissolution , medicago sativa , chemistry , soil water , botany , agronomy , biology , environmental science , soil science , bacteria , genetics
Chloropyromorphite (Pb 5 (PO 4 ) 3 Cl), CP, is the most stable lead (Pb) mineral under normal environmental conditions and precipitates in Pb‐contaminated soils by addition of phosphorous (P). A sand culture experiment was conducted to evaluate the efficiency of Brassica juncea and Medicago sativa roots to dissolve CP in the presence and in the absence of P source. The results showed that the rhizosphere of the plants had lower soluble P and Pb compared with the bulk, which can be attributed to a higher pH in the rhizosphere. Mineralogical transformations of CP in the root surface of the plants including lanarkite (PbSO 4 .PbO) has been confirmed by X‐ray diffraction and scanning electron microscopy techniques. Decrease in soluble P in the rhizosphere as a consequence of P uptake by the plant roots may be a reason for CP dissolution. This study indicates that the dissolution of CP can be promoted by rhizosphere processes.