The nonsteroidal anti-inflammatory drug diclofenac (DCF) is considered a contaminant of emerging concern. DCF can co-exist with heavy metals in aquatic environments, causing unexpected risks to aquatic organisms. This study aimed to assess the combined effects of DCF and cadmium (Cd) at environmentally relevant concentrations on the bioconcentration and status of oxidative stress and detoxification in Chironomus riparius larvae. The larvae were exposed to DCF (2 and 20 μg L⁻¹) and Cd (5 and 50 μg L⁻¹) alone or in mixtures for 48 h. The combined exposure to DCF and Cd was found to reciprocally facilitate the accumulation of each compound in larvae compared with single exposures. As indicated by the antioxidant enzyme activities, reduced glutathione levels, and malondialdehyde contents, the low concentration of the mixture (2 μg L⁻¹ DCF + 5 μg L⁻¹ Cd) did not alter the oxidative stress status in larvae, while the high concentration of the mixture (20 μg L⁻¹ DCF + 50 μg L⁻¹ Cd) induced stronger oxidative damage to larvae compared with single exposures. The expression levels of eight genes (CuZnSOD, MnSOD, CAT, GSTd3, GSTe1, GSTs4, CYP4G, and CYP9AT2) significantly decreased due to the high concentration of the mixture compared with single exposures in most cases. Overall, the results suggest that the mixture of DCF and Cd might exert greater ecological risks to aquatic insects compared with their individual compounds.

非甾体类抗炎药双氯芬酸（DCF）被认为是引起人们关注的污染物。DCF可以与重金属在水生环境中共存，对水生生物造成意想不到的风险。这项研究旨在评估在环境相关浓度下DCF和镉（Cd）对河岸线虫（Chironomus riparius）幼虫的生物浓度以及氧化应激和排毒状态的综合影响。幼虫暴露于DCF（2和20μgL ^-1）和Cd（5和50μgL ^-1）单独或混合48小时。与单次接触相比，发现DCF和Cd的共同接触可促进每种化合物在幼虫中的积累。如抗氧化酶活性，降低的谷胱甘肽水平和丙二醛含量所示，低浓度的混合物（2μgL ^-1 DCF + 5μgL ^-1 Cd）不会改变幼虫的氧化应激状态，而与单次接触相比，浓度较高的混合物（20μgL ^-1 DCF + 50μgL ^-1 Cd）对幼虫的氧化损伤更强。八个基因（CuZnSOD，MnSOD，CAT，GSTd3，与大多数情况下的单次暴露相比，由于混合物的高浓度，GSTe1，GSTs4，CYP4G和CYP9AT2）显着降低。总体而言，结果表明，DCF和Cd的混合物与其单独的化合物相比，可能对水生昆虫造成更大的生态风险。