Ecotoxicological Effects of Combined Pollution from Cadmium and Prometryn on Earthworms

To investigate the biochemical toxicity and cytotoxicity of the heavy metal cadmium and the pesticide prometryn, their single and combined effects on soil animals were studied. Specifically, the study examined how these exposures affected the levels of acetylcholinesterase(AchE), superoxide dismutase(SOD) activity, malondialdehyde(MDA) levels, and the growth of the earthworm species Eisenia fetida, which served as the test organism. The study also assessed reproduction, avoidance behavior, and DNA damage in coelomocytes. The results showed that the LC₅₀ of prometryn for earthworms at 24 h and 48 h were 66.72 mg/kg and 29.41 mg/kg, respectively, which were 11.03 and 12.67 times higher than those of cadmium, obtained by the filter paper method; AchE and SOD activities in earthworms were significantly inhibited with the extension of the dyeing time under the combined exposure of cadmium and prometryn; compound pollution resulted in enhanced oxidative damage in earthworms, with all MDA levels higher than those in the single treatment group; earthworm body weight was not significantly suppressed within 21 d of combined exposure, but reproduction was significantly reduced, and avoidance responses were more significant; combined exposure to cadmium and prometryn induced DNA damage in the coelomocyte of earthworms, and there was a dose-effect relationship with the concentration of the 2 composite pollutants. The combined exposure of cadmium-prometryn resulted in more severe toxicity to earthworms, aggravated the oxidative stress effect of the organism, and enhanced the environmental stress.