Quantum Yields for Direct Photolysis of Neonicotinoid Insecticides in Water: Implications for Exposure to Nontarget Aquatic Organisms

• DOI: 10.1021/acs.estlett.5b00136
• Publication Date: 2015-06-16T18:11:06Z
• Authors: Zhe Lu; Jonathan K. Challis; Charles S. Wong
• Keywords: Clothianidin; Neonicotinoid; Thiacloprid; Detritus; Acetamiprid

Environmental fate processes of neonicotinoid insecticides are significant interest, given the serious threats these chemicals can pose to nontarget organisms such as pollinators (e.g., bees). Direct photolysis was investigated using a laboratory photoreactor approximating full-spectrum sunlight predict aquatic neonicotinoids. Quantum yields (ϕc) were 0.019 ± 0.001, 0.013 0.0092 0.0005, 0.0022 0.0003, and 0.0013 0.0002 for thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid, respectively. On basis values, estimated half-lives 0.2–1.5 days different seasons in surface waters at temperate latitudes consistent with 0.98 day half-life observed experimentally outdoors Winnipeg, Manitoba, Canada (50°N), thiamethoxam summer. Light attenuation through shallow clear by natural organic matter) indicated that depths greater than 8 cm negligible, which may help explain reports its environmental persistence.