title: Photodegradation of α-cypermethrin in soil in the presence of trace metals (Cu2+, Cd2+, Fe2+ and Zn2+).
abstract: The influence of trace metals (Cu(2+), Zn(2+), Cd(2+) and Fe(2+)) on the photodegradation of α-cypermethrin (α-CYM) in agricultural soil was studied. The soil samples were spiked with α-cypermethrin with/without the presence of metal ions, irradiated under a UV irradiation chamber for a regular period of time and analyzed by using HPLC. The dark control sterile and unsterile soil samples spiked with α-cypermethrin and selected trace metals were incubated for the same interval of time at 25 °C. The results obtained indicated that α-cypermethrin photodegradation followed biphasic kinetics. α-cypermethrin photodegradation half-lives (t1/2) were increased to 0.71 and. 4.5 hours from 0.64 hours respectively in the presence of elevated Zn(2+) and Cu(2+) concentrations. Fe(2+) and Cd(2+) increased the photodegradation reaction kinetics from -1.078 h(-1) to -1.175 h(-1) and -1.397 h(-1) and varied the t1/2 from 0.64 ± 1.41 to 0.59 ± 2.07 and 0.49 ± 2.01 in the soil. Microbes also affected the degradation of α-cypermethrin in metal contaminated soil. The degradation rate was inhibited in unsterile soil and was found to be in the following order: Cd(2+)< Zn(2+)< Cu(2+)< Fe(2+). The degradation/persistence of α-cypermethrin was affected linearly with the increasing soil metal concentrations.
authors.affiliation: Department of Chemistry, Lahore College for Women University, Lahore, Pakistan. naziarafiqchem@gmail.com saadiartariq@yahoo.com.
authors.forename: Nazia
authors.initials: N
authors.lastname: Rafique
authors.forename: Saadia R
authors.initials: SR
authors.lastname: Tariq
mesh_terms: D000383:Agriculture; D007306:Insecticides / Q000032:analysis / Q000737:chemistry*; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D010782:Photolysis; D011722:Pyrethrins / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D007306:Insecticides; D019216:Metals, Heavy; D011722:Pyrethrins; D012987:Soil; D012989:Soil Pollutants; C017160:cypermethrin