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Influence of Chelating Ligands on Arsenic Uptake by Hydroponically Grown Rice Seedlings ( Oryza sativa L.): A Preliminary Study
Author(s) -
Rahman Mohammad Azizur,
Hasegawa Hiroshi,
Ueda Kazumasa,
Maki Teruya,
Rahman M. Mahfuzur
Publication year - 2008
Publication title -
clean – soil, air, water
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 66
eISSN - 1863-0669
pISSN - 1863-0650
DOI - 10.1002/clen.200800048
Subject(s) - edds , arsenic , chemistry , arsenate , chelation , phytoremediation , oryza sativa , ethylenediaminetetraacetic acid , nitrilotriacetic acid , rhizosphere , arsenite , nuclear chemistry , shoot , environmental chemistry , inorganic chemistry , botany , biochemistry , heavy metals , organic chemistry , biology , genetics , bacteria , gene
Abstract Ferric (oxyhydro‐)oxides (FeO x ) precipitate in the rhizosphere at neutral or alkaline pH and are adsorbed on the plant root surfaces. Consequently, the higher binding affinity of arsenate to FeO x and the low iron phytoavailability of the precipitated FeO x make the phytoremediation of arsenic difficult. In the present study, the influence of chelating ligands on arsenic and iron uptake by hydroponically grown rice seedlings ( Oryza sativa L.) was investigated. When chelating ligands were not treated to the growth medium, about 63 and 71% of the total arsenic and iron were distributed in the root extract (outer root surfaces) of rice, respectively. On the other hand, ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS) and hydroxyiminodisuccinic acid (HIDS) desorbed a significant amount of arsenic from FeO x of the outer root surfaces. Therefore, the uptake of arsenic and iron into the roots and their subsequent translocation to the shoots of the rice seedlings increased significantly. The order of increasing arsenic uptake by chelating ligands was HIDS > EDTA > EDDS. Methylglycinediacetic acid (MGDA) and iminodisuccinic acid (IDS) might not be effective in arsenic solubilization from FeO x . The results suggest that EDDS and HIDS would be a good and environmentally safe choice to accelerate arsenic phytoavailability in the phytoremediation process because of their biodegradability and would be a competent alternative to the widely used non‐biodegradable and environmentally persistent EDTA.