The co-contamination discharge of Phthalate esters (PAEs) by human activities and the increased UV radiation is increasing in aquatic ecosystems. However, little information is available about the combined detrimental effects of UV and PAEs on phytoplankton. In this study, the combined effects of UV-B irradiation and di-(2-ethylhexyl) phthalate (DEHP) on photosynthesis and antioxidant system of Scenedesmus acuminatus, and the DEHP degradation were investigated. Results showed that UV-B radiation decreased the chlorophyll a fluorescence yield, photosynthetic activity (Fv/Fm), pigment content and superoxide dismutase activity. This radiation also increased the reactive oxygen species (ROS) production and soluble protein and malondialdehyde contents. UV-B radiation with 10 mg L⁻¹ DEHP improved the Fv/Fm and alleviated the cell damage of S. acuminatus, and the addition of high DEHP concentration (≥50 mg L⁻¹) aggravated cell damage. The ROS generation also decreased with the increased DEHP concentration. UV-B radiation can effectively promote the DEHP degradation, with the highest degradation rate of 89.9% at an initial DEHP concentration of 10 mg L⁻¹ within 6 h. This result may be attributed to that UV-B irradiance induced DEHP degradation under the regulation of ROS generated by S. acuminatus. Our findings will contribute to the understanding of the combined toxic mechanisms of UV-B and DEHP and in the evaluation of ecological environment risks for primary producers in aquatic ecosystems.

在水生生态系统中，人类活动和邻苯二甲酸酯（PAE）的共污染排放正在增加。但是，关于紫外线和PAE对浮游植物的综合有害影响的信息很少。本研究研究了UV-B辐射和邻苯二甲酸二（2-乙基己基）酯（DEHP）对尖角藻光合作用和抗氧化系统的联合作用以及DEHP的降解。结果表明，UV-B辐射降低了叶绿素a的荧光产量，光合活性（Fv / Fm），色素含量和超氧化物歧化酶活性。这种辐射还增加了活性氧（ROS）的产生以及可溶性蛋白质和丙二醛的含量。10 mg L的UV-B辐射^-1 DEHP可改善Fv / Fm并减轻刺五加对细胞的损伤，而高DEHP浓度（≥50mg L ^-1）的添加会加剧细胞损伤。随着DEHP浓度的增加，ROS的产生也减少。UV-B辐射可有效促进DEHP降解，在6 h内初始DEHP浓度为10 mg L ^-1时，最高降解率为89.9％。该结果可能归因于在由S. acuminatus产生的ROS的调节下，UV-B辐照导致DEHP降解。。我们的发现将有助于理解UV-B和DEHP的综合毒性机理，并有助于评估水生生态系统初级生产者的生态环境风险。