title: Use of duckweed (Lemna disperma) to assess the phytotoxicity of the products of Fenton oxidation of metsulfuron methyl.
abstract: Because of pressure on water supplies world-wide, there is increasing interest in methods of remediating contaminated ground waters. However, with some remediation processes, the breakdown products are more toxic than the original contaminant. Organic matter and salinity may also influence degradation efficiency. This study tested the efficiency of Fenton oxidation in degrading the sulfonylurea herbicide metsulfuron methyl (MeS), and tested the reaction products for phytotoxicity with the Lemna (duckweed) bioassay. The efficiency of degradation by Fenton's reagent (Fe(2+)=0.09 mM; H(2)O(2)=1.76 mM, 4h) decreased with increasing initial MeS concentration, from 98% with 5 mg/L MeS, to 63% with 70 mg/L MeS. Addition of NaCl (10mM) and organic matter (humic acid at 0.2 and 2.0mg C/L as Total Organic Carbon) reduced the efficiency of degradation at low initial MeS concentrations (5 and 10 mg/L), but had no effect at high concentrations. The residual Fenton's reagent after Fenton's oxidation was toxic to Lemna. After removal of residual iron and H(2)O(2), the measured toxicity to Lemna in the treated samples could be explained by the concentrations of MeS as measured by HPLC/UV detection, so there was no evidence of additional toxicity or amelioration due to the by-products or formulation materials.
authors: Faculty of Engineering and IT, University of Technology, Sydney, Broadway, NSW 2007, Australia.
authors: Javeed M
authors: JM
authors: Abdul
authors: Anne
authors: A
authors: Colville
authors: Richard
authors: R
authors: Lim
authors: Saravanamuthu
authors: S
authors: Vigneswaran
authors: Jaya
authors: J
authors: Kandasamy
mesh_terms: D029064:Araceae / Q000187:drug effects*; D001190:Arylsulfonates / Q000633:toxicity*; D001673:Biodegradation, Environmental; D006812:Humic Substances; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000633:toxicity*; D007501:Iron / Q000737:chemistry / Q000633:toxicity*; D010084:Oxidation-Reduction; D012965:Sodium Chloride / Q000494:pharmacology; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D001190:Arylsulfonates; C045076:Fenton's reagent; D006812:Humic Substances; D014874:Water Pollutants, Chemical; C050296:metsulfuron methyl; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D007501:Iron