Stress Effect Induced by Microplastics Coupled with Acid Rain, on Garden Cress, During Short and Long Time: Two Exposures in Comparison

Aim: Plastics, and acid rain, are the results of the anthropogenic activities; although, the injuries caused by acidic precipitation to plants are well known, what happen if acid rain is coupled with microplastics pollution? Methods: In this experiment, we simulated, under controlled condition, a contaminated area from four different kinds of Microplastics (MPs): Polyethylene (PE), Polyvinylchloride (PVC), commercial mixture (PE + PVC) and Polypropylene (PP) subjected to acidic precipitation on Lepidium sativum, both in short then long exposures. At the end of experimentation were analysed: i) plant biometrical parameters (percentage inhibition of seed germination, plant height, leaf number and fresh biomass productions); and ii) oxidative stress (e.g., levels of hydrogen peroxide, glutathione, and ascorbic acid). On plant subjected to long exposure are quantified also: lipidic peroxidation through Malondialdehyde (MDA) concentration, Aminolevulinic Acid (AlA), pigments (Chl-a, Chl-b, carotenoids) and soluble sugars. Results: Our results suggest that root system is more sensitive to MPs coupled with acid rain then above ground biomass. Furthermore, in short exposure toxicity begin with PE+ treatments to shift towards PVC+ toxicity in long exposure at radical level. Conclusion: Our experiment demonstrates that different kinds of microplastics supplied with acid rain are able to interfere in different ways both in short and in long exposure, but also at shoot and root levels, on garden cress.