title: Arsenic uptake by aquatic macrophyte Spirodela polyrhiza L.: interactions with phosphate and iron.
abstract: The uptake of arsenate (As(V)) and dimethylarsinic acid (DMAA) by aquatic macrophyte Spirodela polyrhiza L. was investigated to determine the influence of arsenic interaction with PO4(3-) and Fe ions. Plants were grown hydroponically on standard Murashige and Skoog (MS) culture solutions. Arsenic concentrations in Fe-oxide (Fe-plaque) on plant surfaces were determined by citrate-bicarbonate-ethylenediaminetetraacetic acid (CBE) technique. S. polyrhiza L. accumulated 51-fold arsenic from arsenate solution compared to that from DMAA solution with initial concentrations of 4.0 and 0.02microM of arsenic and phosphate, respectively. The arsenate uptake was negatively (p<0.001) correlated with phosphate uptake and positively (p<0.05) correlated with iron uptake. About 56% of the total arsenic was accumulated into the plant tissues while 44% was adsorbed on Fe-plaque (CBE-extract), when the plants were grown on arsenate solution. The DMAA uptake into the plant was neither affected by the phosphate concentrations nor correlated (p>0.05) with iron accumulation. The results suggest that adsorption of arsenate on Fe-plaque of the surface of S. polyrhiza L. contributes to the arsenic uptake significantly. Thus, arsenate uptake in S. polyrhiza L. occurred through the phosphate uptake pathway and by physico-chemical adsorption on Fe-plaques of plant surfaces as well. The S. polyrhiza L. uses different mechanisms for DMAA uptake.
authors.affiliation: Graduate School of Natural Science & Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: M Azizur
authors.initials: MA
authors.lastname: Rahman
authors.forename: H
authors.initials: H
authors.lastname: Hasegawa
authors.forename: K
authors.initials: K
authors.lastname: Ueda
authors.forename: T
authors.initials: T
authors.lastname: Maki
authors.forename: M Mahfuzur
authors.initials: MM
authors.lastname: Rahman
mesh_terms: D001149:Arsenates / Q000737:chemistry; D001152:Arsenicals / Q000378:metabolism*; D001639:Bicarbonates / Q000737:chemistry; D002101:Cacodylic Acid / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry; D002951:Citrates / Q000737:chemistry; D003627:Data Interpretation, Statistical; D004492:Edetic Acid / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D010944:Plants / Q000737:chemistry / Q000378:metabolism*; D013054:Spectrophotometry, Atomic
chemical_list: D001149:Arsenates; D001152:Arsenicals; D001639:Bicarbonates; D002614:Chelating Agents; D002951:Citrates; D005290:Ferric Compounds; D010710:Phosphates; C021024:ferric hydroxide; D004492:Edetic Acid; D002101:Cacodylic Acid; D007501:Iron