In surface waters, the illumination of photoactive engineered nanomaterials (ENMs) with ultraviolet (UV) light triggers the formation of reactive intermediates, consequently altering the ecotoxicological potential of co‐occurring organic micropollutants including pesticides due to catalytic degradation. Simultaneously, omnipresent natural organic matter (NOM) adsorbs onto ENM surfaces, altering the ENM surface properties. Also, NOM absorbs light, reducing the photo(cata)lytic transformation of pesticides. Interactions between these environmental factors impact 1) directly the ecotoxicity of photoactive ENMs, and 2) indirectly the degradation of pesticides. We assessed the impact of field‐relevant UV radiation (up to 2.6 W UVA/m²), NOM (4 mg TOC/L), and photoactive ENM (nTiO₂, 50 µg/L) on the acute toxicity of 6 pesticides in Daphnia magna. We selected azoxystrobin, dimethoate, malathion, parathion, permethrin, and pirimicarb because of their varying photo‐ and hydrolytic stabilities. Increasing UVA alone partially reduced pesticide toxicity, seemingly due to enhanced degradation. Even at 50 µg/L, nano‐sized titanium dioxide (nTiO₂) reduced but also increased pesticide toxicity (depending on the applied pesticide), which is attributable to 1) more efficient degradation and potentially 2) photocatalytically induced formation of toxic by‐products. Natural organic matter 1) partially reduced pesticide toxicity, not evidently accompanied by enhanced pesticide degradation, but also 2) inhibited pesticide degradation, effectively increasing the pesticide toxicity. Predicting the ecotoxicological potential of pesticides based on their interaction with UV light or interaction with NOM was hardly possible, which was even more difficult in the presence of nTiO₂. Environ Toxicol Chem 2020;39:2237–2246. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

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在田间条件下降低农药毒性？二氧化钛纳米粒子，紫外线和天然有机物的相互作用

在地表水中，用紫外线（UV）照射光敏工程纳米材料（ENM）触发了反应性中间体的形成，因此由于催化降解而改变了包括农药在内的共生有机微量污染物的生态毒理学潜力。同时，无所不在的天然有机物（NOM）吸附到ENM表面上，从而改变了ENM表面特性。另外，NOM吸收光，减少了农药的光催化转化。这些环境因素之间的相互作用影响1）直接影响光敏ENM的生态毒性，以及2）间接影响农药的降解。我们评估了与场相关的紫外线辐射（高达2.6 W UVA /m²），NOM（4 mg TOC / L）和光敏性ENM（nTiO ₂，50 µg / L）对6种农药对大型蚤的急性毒性。我们选择了嘧菌酯，乐果，马拉硫磷，对硫磷，氯菊酯和吡虫威，因为它们具有不同的光稳定性和水解稳定性。单独增加UVA可能部分降低了农药的毒性，这似乎是由于降解加剧所致。即使浓度为50 µg / L，纳米级二氧化钛（nTiO ₂）降低但也增加了农药的毒性（取决于所施用的农药），这可归因于1）更有效的降解以及潜在的2）光催化诱导的有毒副产物的形成。天然有机物1）部分降低了农药的毒性，没有明显伴随农药降解的增加，而且2）抑制了农药的降解，有效地提高了农药的毒性。很难根据农药与紫外线的相互作用或与NOM的相互作用来预测农药的生态毒理学潜力，而在存在nTiO ₂的情况下，农药的生态毒理学潜力就更大了。Environ Toxicol Chem 2020； 39：2237-2246。©2020作者。环境毒理学与化学 由Wiley Periodicals LLC代表SETAC发行。