Toxic Effects Of Typical Microplastics On Dominant Benthic Animals

Microplastics(MPs)refer to plastic fragments or granules having a particle size of less than 5mm.As a new type of pollutant in the environment,microplastics has become a hot spot in the current research on the interaction between biological and microplastics and the ecotoxicity of microplastic pollution.In this paper,three types of microplastic low-density polyethylene(LDPE),polycaprolactam(PA6),and polyvinyl chloride(PVC)were used as experimental materials,and the Limnodrilus hoffmeisteri and Chironomid were the main tested organisms.A series of toxicological experiments were carried out from the perspectives of mortality,growth and development,oxidative stress and metabolic chemistry.The research results are:(1)Under the toxic effects of short-term(24h or 48h)and long-term(28d)microplastics,the toxic effects of PA6 on Limnodrilus hoffmeisteri and Chironomid were significant compared with LDPE and PVC;The microplastic concentration did not show a significant dose-effect relationship with the mortality,body length and body weight of Limnodrilus hoffmeisteri and Chironomid;Microplastics have certain toxic effects on Limnodrilus hoffmeisteri and Chironomid,and the long-term effects are more obvious than short-term toxic effects;Compared with Limnodrilus hoffmeisteri,the response of Chironomid to microplastics toxic effects is more significant;(2)The toxic effect of high concentration of microplastic PA6 can stimulate the oxidative stress reaction of aquatic organisms,but there are also differences in exposure time;LDPE did not cause significant oxidative damage to Chironomid and Limnodrilus hoffmeisteri;The change of PVC concentration has a more significant effect on the antioxidant system of Limnodrilus hoffmeisteri and Chironomid,and has obvious damage to the antioxidant system of aquatic organisms;(3)Microplastic LDPE and PVC have certain influence on the changes of the material composition in Limnodrilus hoffmeisteri,especially for the metabolism of saturated and unsaturated fatty acids;The toxic effect of high concentration LDPE and PVC reduced the content of fatty acids in Limnodrilus hoffmeisteri excretion as a whole,but the type and content of fatty acids detected increased under low concentration conditions.Secondly,compared with PVC,LDPE has a more significant effect on the change of fatty acids in the excrement of Limnodrilus hoffmeisteri.This study investigated the toxic effects of typical microplastics on the mortality,growth and development,antioxidant system and metabolic chemistry of Chironomid and Limnodrilus hoffmeisteri.The study provides valid data for understanding and assessing the toxic effects of microplastics in freshwater environments and establishing biotoxic-based sediment quality benchmarks.