International Journal of Science, Engineering and TechnologyAuthors: Dr. Kalpana Singh
Abstract: Microplastic contamination and rising environmental temperatures are two of the most pressing pressures on the Earth ecosystem and may have serious effects on the soil-dwelling invertebrates. Although the biological effects of microplastics and heat stress have been studied on their own, the combined impacts in soil animals and environment are not well understood. In this paper we provide a critical narrative review of the potential interactions between microplastic exposure and heat stress in soil invertebrates and examine biological effects, ecological effects and research challenges related to the combination of the two environmental stressors. It considers published studies on oxidative stress, feeding behaviour, energy utilization, growth, reproduction, survival and physiological responses of earthworms, springtails, mites and nematodes. We also study how microplastic features, including particle size, shape, polymer composition and concentration, may affect biological responses at higher temperatures. The review also explores the potential effects of combined exposure on decomposition, nutrient cycling, soil structure and soil fauna and microorganisms. It notes that the effects of combined exposure may be additive, synergistic, antagonistic or negligible depending on the organism, exposure conditions and environment. Thus, the effects of microplastic exposure and heat stress should not be expected to be more than the effects of individual stressors in every case. By combining the findings from previous literature, in this paper we have highlighted some of the major knowledge gaps in the field of realistic exposure conditions, long-term ecological response and the mechanisms of combined-stressor effects. We stress that we need to include multiple environmental pressures in soil ecotoxicology and that we need to develop evidence-based approaches to maintain soil biodiversity and ecosystem functioning under changing climatic conditions.
