COMBINED EFFECTS OF POLYSTYRENE MICROPLASTICS AND GREEN SYNTHSIZED IRON-OXIDE NANOPARTICLES ON PHYSICOCHEMICAL PROPERTIES AND NUTRIENT PROFILE OF COPPER STRESSED SOIL

Abstract

Background Soil is a vital component of agriculture, providing essential nutrients and support for plant growth. However, soil health can be negatively impacted by various stressors, such as heavy metal pollution, microplastics contamination and nanoparticles. Soil physicochemical parameters and nutrient status are important to observe in the presence of these stressors. Objectives The study aimed to investigate the combined impact of polystyrene microplastics (PSMPs) and green synthesized iron oxide nanoparticles (GIONPs) on the physiochemical properties of Cu stressed soil. Furthermore, the impact of PSMPs, GIONPs were also observed on micro and macro-nutrients as well as heavy metals of Cu stressed soil. Methodology Different concentrations of Cu (0, 50, 100, 200, and 400mg/kg) PSMPs (0%, 1% and 3% w/w) and GIONPs (100ppm) were added to soil contains 3% w/w organic matter. Soil physicochemical properties (pH, EC) and nutrients profile was analysed via atomic adsorption spectrophotometer-(ASS). Micronutrients included (Fe, Zn, Cu, Mn), Macronutrients (No3- , Po4 3-) and Heavy metals (Pb, Cd). Analysis carried out at two stages i.e. pre-sowing soil (14 days incubated soil) and post harvesting soil (after 60 days of maize cultivation). Results The results showed that the increasing concentration of Cu in soil showed a negative effect on soil physicochemical properties and the levels of micronutrients, essential for soil health. Soil pH and EC disrupted with the addition of Cu, PSMPs and GIONPs. The soil pH decreased (8.6-8.4) in both soils, while, EC increased (434 µS/cm -615 µS/cm) in pre-sowing soil with the addition of Cu. However, soil pH (8.6-8.8) and EC (426 µS/cm -580 µS/cm) increased with addition of GIONPs, PSMPs in pre-sowing soil. While, in post-harvest soil pH increased (8.9 -9.13) and EC decreased (130 µS/cm -150 µS/cm) over all with the addition of Cu,PSMPs and XIII GIONPs in soil. Cu, PSMPs and GIONPs adsorbed the nutrients in pre-sowing and post-harvest soil. However, PSMPs and GION showed less reduction as compared to Cu in post-harvest soil significantly ,the concentration ranged from 307 mg/kg -12 mg/kg, 8342 mg/kg- 8342 mg/kg, 389 mg/kg- 280 mg/kg, 44 mg/kg – 30 mg/kg and 19 mg/kg -10 mg/kg, 31mg/kg -19 mg/kg respectively. The adsorption capacity of GIONPs was greater as compared to PSMPs in soil. Addition of GIONPs adsorbed more as compared to PSMPs in soil. Moreover, addition of 3% PSMPs showed greater adsorption as compared to 1% PSMPs in soil. Conclusion Cu, PSMPs and GIONPs acted as vector of nutrients in this study, thus reduced the bioavailability of nutrients in soil. The significant difference in soil pH, EC and nutrients was observed in pre- sowing and post-harvest soil. Moreover, the adsorption capacity of GIONPs was greater as compared to PSMPs in soil as the addition of GIONPs adsorbed more as compared to PSMPs in soil. Additionally, addition of 3% PSMPs showed greater adsorption as compared to 1% PSMPs in soil. This research highlights the need to consider the combined impact of multiple stressors on soil health and nutrient status. However, this research provides valuable insights into the complex relationships between different soil stressors and their impact on soil health and nutrient status.