Arseniccompoundsinleavesandrootsofradishgrownin Arseniccompoundsinleavesandrootsofradishgrownin soiltreatedbyarsenite,arsenateanddimethylarsinicacid soiltreatedbyarsenite,arsenateanddimethylarsinicacid ² Pavel Tlustos Ï 1 *, Walter Goessler 2 , Jir Ïina Sza  kova  1 and Jir Ïi BalõÂk 1 1 Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture, CZ-165 21 Prague 6, Suchdol, Czech Republic 2 Institute for Chemistry, Karl-Franzens-University Graz, Universita ¨tsplatz 1, A-8010 Graz, Austria Received 12 June 2001; Accepted 13 December 2001 The effect of arsenite [arsenicIII)], arsenate [arsenicV)] and dimethylarsinic acid DMA) on the growthofradishandtheconcentrationofarseniccompoundsintherootsandleavesofradishwere investigated. Radish was grown in pots on Luvisols individually amended with arsenic concentrations of 20mgkg 1 in the form of arsenicIII), arsenicV), and DMA. In untreated soil, arsenate was the dominant arsenic compound; arsenite and DMA were also present. ArsenicIII) added to the soil was oxidized to arsenicV), so that no differences between arsenicIII) and arsenicV) soil treatments were observed. On DMA treatment, this compound remained in soil in highconcentrationinsolubleandplant-availablestates,andthesumofarsenicIII),arsenicV)and methylarsonicacidMA)reachedonly30%ofwater-extractablearseniccontent.Alowportionofsoil arsenic added as DMA was immobilized, via adsorption, compared with inorganic compounds. ArsenicIII) was the dominant compound in radish roots planted in the untreated soil, whereas in leavesmostofthearsenicpresentwasarsenicV).DMAwasalsodetectedinbothplanttissues.A similardistributionofarseniccompoundswasalsofoundonarsenicIII)andarsenicV)treatments. OnDMAtreatment,thiscompoundshowedhighstabilityandtheDMAconcentrationexceededthe sumoftheremainingarseniccompounds[arsenicIII),arsenicV)andMA]inbothrootsandleaves of radish. Copyright # 2002JohnWiley&Sons,Ltd. KEYWORDS: radish; arsenite; arsenate; dimethylarsinic acid; soil; HPLC±ICP-MS; plant availability INTRODUCTION Arsenic behavior and its transformations in soil and dependence on different physicochemical soil properties are widely investigated. 1 The influences of soil texture, pH, redox potential, organic matter content, inter-element inter- actions on arsenic sorption/desorption and plant availability have already been discussed. 1±3 However, there is very little detailed information to be found concerning individual arsenic compounds in soil. The literature suggests that arsenic in soil is present mostly in the pentavalent state, but that it can be easily changed to arsenite under reducing soil conditions. 2±5 When the redox potential of soil suspensions dropped below 0 mV, most of the arsenic was present as arsenite [arsenicIII)]. Under partially oxidizing conditions both arsenicIII) and arsenate [arsenicV)] were present. 4 Small percentages of methylated arsenic compounds in soils were also reported. 5 Mineralization of organoarsenicals in soil under different soil conditions was also mentioned. The main metabolite from degradation of methylarsonic acid MA) and dimethylarsinic acid DMA) was arsenate, and DMA demethylates directly to arsenicV) rather than through MA as an intermediate. 5 The rate of MA miner- alization was slower than that of DMA under the same conditions. Transformation of arsenate to MA or of MA to DMA was negligible. 6 Phytoavailability and phytotoxicity of individual arsenic compounds in soils were summarized by Sheppard. 7 Differences in arsenic responses were probably caused by the soil properties and the source of arsenic. Inorganic and *Correspondence to: P. Tlustos Ï, Department of Agrochemistry and Plant Nutrition, Czech University of Agriculture, CZ-165 21 Prague 6, Suchdol, Czech Republic. ² This paper is based on work presented at the 5th International Conference on Environmental and Biological Aspects of Main-Group Organometals ICEBAMO-5) held at Schielleiten, near Graz, Austria, 5±9 June 2001. Contract/grant sponsor: Grant Agency of Czech Republic; Contract/ grant number: 511/95/0557. Contract/grant sponsor: AKTION O È stereich±Tschechische Republic; Contract/grant number: 500 12. DOI:10.1002/aoc.282 Copyright # 2002 John Wiley & Sons, Ltd. APPLIED ORGANOMETALLIC CHEMISTRY Appl. Organometal. Chem. 2002; 16: 216±220