10.1021/acs.estlett.5b00136.s001 Zhe Lu Zhe Lu Jonathan K. Challis Jonathan K. Challis Charles S. Wong Charles S. Wong Quantum Yields for Direct Photolysis of Neonicotinoid Insecticides in Water: Implications for Exposure to Nontarget Aquatic Organisms American Chemical Society 2015 thiamethoxam quantum Nontarget Aquatic OrganismsEnvironmental fate processes e.g photolysi surface waters neonicotinoid Direct 2015-07-14 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Quantum_Yields_for_Direct_Photolysis_of_Neonicotinoid_Insecticides_in_Water_Implications_for_Exposure_to_Nontarget_Aquatic_Organisms/2150455 Environmental fate processes of neonicotinoid insecticides are of 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 to predict the aquatic fate of neonicotinoids. Quantum yields (ϕ<sub>c</sub>) were 0.019 ± 0.001, 0.013 ± 0.001, 0.0092 ± 0.0005, 0.0022 ± 0.0003, and 0.0013 ± 0.0002 for thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid, respectively. On the basis of these values, estimated half-lives were 0.2–1.5 days for different seasons in surface waters at temperate latitudes for thiamethoxam, consistent with the 0.98 day half-life observed experimentally outdoors at Winnipeg, Manitoba, Canada (50°N), for thiamethoxam in summer. Light attenuation through shallow clear surface waters (e.g., by natural organic matter) indicated that photolysis of thiamethoxam at depths greater than 8 cm was negligible, which may help explain reports of its environmental persistence.