Microplastics (MPs) are now ubiquitous in global ecosystem, therefore all biota is at risk of exposure and potential toxicity. In this study, we presented an overview of information based on literature concerning exposure to MPs and the toxicity of such exposure. Currently, four major routes of exposure have been identified including entanglement, contact, ingestion and inhalation. Humans maybe the most exposed organism because they are at the peak of the food chain. Toxicology effect to marine and freshwater organisms are classified based on exposure dosage as either high (mortality, decreased reproductive output, organ damage) or low (changes in behavior with time). On plants, reports have shown that MPs exposure can affect negatively the growth and depending on exposure concentration and types of MPs and oxidative activities. However, effects on plants maybe short-term and transient. Although, toxicity studies regarding human are still ongoing as per reports, plants and animals are still scantly studied. Animal toxicity studies have widely used D. magna as model specie. MPs pollution may have a knock-on effect on trophic structure and functioning of ecosystems by affecting the base of the food chain. We concluded by identifying the gap in knowledge and give recommendations for future research.

Contamination of soils in agroecosystems with microplastics (MPs) is of increasing concern. The contamination of the environment/farmland soils with MPs (1 µm to 5 mm sized particles) and nanoplastics (NPs; <1 µm sized particles) is causing numerous effects on ecological soil functions and human health. MPs enter the soil via several sources, either from intentional plastic use (e.g., plastic mulch, plastic greenhouses, plastic‐coated products) or indirectly from the input of sewage sludge, compost, or irrigation water that is contaminated with plastic. Once in the soil, plastic debris can have various impacts such as changes in soil functions and physicochemical properties and it affects soil organisms due to its toxic behavior. This review paper describes the different effects of plastic waste to understand the consequences for agricultural productivity. Furthermore, we identify knowledge gaps and highlight the required approaches, indicating future research directions on sources, transport, and fate of MPs in soils to improve our understanding of various unspecified abiotic and biotic impacts of MP pollution in agroecosystems.

Numerous methods are available for sampling, extracting, and detecting microplastics (MP; 0.001–5 mm) in soil. However, previous studies mostly focused on pristine MP and changing surface properties due to ageing (e.g. surface photooxidation) that will impact transport in soils are not considered. This study primarily aimed at MP recovery from soil by density separation, focusing on the impact of UV-aging on recovery rates while monitoring MP surface properties to avoid analytical artifacts. Thus, we mixed sandy loam and silt loam topsoil with both, pristine and UV-aged polyethylene terephthalate (PET) and polystyrene (PS) MP, produced from PET bottles and PS plates in three size classes. MP particles were recovered by density separation, using oversaturated NaCl and NaI, solutions, followed by H ₂ O ₂ -treatment to oxidise soil organic matter. Recovery rates were determined gravimetrically after filtration of the supernatant. MP surface properties were characterised by FTIR, Nile red staining, contact angle (CA), and XPS analysis before and after recovery. Recovery rates averaged 81.0%, ranging from 56.5% to 89.7%, with no defined differences between MP type, size, and variant (pristine, UV-aged). Before recovery, FTIR analysis revealed an increase in carbonyl groups, Nile red staining showed a darker colour, CA was significantly decreased, and XPS indicated an increase in surface O/C ratio for UV-aged MP. After recovery, FTIR and Nile red analysis showed no changes, CA of UV-aged MP, however, was found to be increased, probably due to H ₂ O ₂ -treatment that may have removed the oxidised surface layer. In summary, the separation procedure applied was found to successfully recover pristine and UV-aged MP from both, sand and silt soil, regardless of MP type tested (PET, PS).

Comparing pristine microplastic (MP) to aged MP collected from the soil environment, aged MP particles generally have a rougher surface and thus a greater specific surface area, higher crystallinity, more oxygen-containing functional groups, and lower tensile strength, as well as greater mobility and consequently a higher risk of leaching into the groundwater [1, 2]. The aged MP is produced due to the solar UV irradiation and soil abiotic and biotic processes [3]. Thus, pristine and aged MP may behave differently in the environment due to different surface properties and MP extraction from soil consequently must ensure to recover both, pristine and aged MP. Therefore, we aimed to develop a fast and efficient laboratory method to detect pristine and aged MP and to compare the recovery rate of aged and pristine MP. For this purpose, an experiment was conducted by adding pristine and UV-aged (UV irradiation period: 35 d) MP particles of two different types, polyethylene terephthalate (PET) and polystyrene (PS), at three sizes (S: 500 µm, M: 500-630 µm, L: 630 µm -1mm) to sand and loess soil at a concentration of 0.5% w/w. For extraction, a density separation was performed, using saturated NaCl (1.2 g cm-3) and NaI (1.8 g cm- 3) solutions, followed by H2O2 (33 %) treatment to remove soil organic matter. Recovered MP was quantified gravimetrically. The physico-chemical properties of pristine and aged MP before and after extraction were analyzed by Mid-FTIR for changes in surface functional groups and by contact angle (CA) determination for changes in wetting properties due to aging. We found that the recovery rates of pristine and UV-aged particles were the same for both PS and PET, with no significant differences between recovery from sand and loess soils. The average recovery rate of all samples was about 81 %. Pristine MP was hydrophobic (CA≥90) while aged MP was subcritically water repellent (CA>0 and 90° after recovery, probably due to amphiphilic organic matter (OM) compounds sorbed during extraction. In conclusion, the tested recovery procedure did work for pristine and aged MP at all size fractions and loess and sandy soils, while the extraction procedure seems to result in an interaction between polar sites and released OM in case of aged MP.Keywords: Microplastic, Pristine, UV-aged, Recovery, Identification, Quantification.[1] doi: 10.1016/j.scitotenv.2018.02.079. [2] doi: 10.1016/j.watres.2021.117407.117407.[3] doi: 10.1002/jpln.202200136.