Microplastics as pollutants in agricultural soils

Abstract

Microplastics (MPs) as emerging persistent pollutants have been a growing global concern.Although MPs are extensively studied in aquatic systems, their presence and fate in agricultural systems are not fully understood. In the agricultural soils, major causes of MPs pollution include application of biosolids and compost, wastewater irrigation, mulching film, polymer-based fertilizers and pesticides, and atmospheric deposition. The fate and dispersion of MPs in the soil environment are mainly associated with the soil characteristics, cultivation practices, and diversity of soil biota. Although there is emerging pollution of MPs in the soil environment, no standardized detection and quantification techniques are available. This study comprehensively reviews the sources, fate, and dispersion of MPs in the soil environment, discusses the interactions and effects of MPs on soil biota, and highlights the recent advancements in detection and quantification methods of MPs. The prospects for future research include biomagnification potency, cytotoxic effects on human/animals, nonlinear behavior in the soil environment, standardized analytical methods, best management practices, and global policies in the agricultural industry for the sake of sustainable development.

Land Application of Biosolids in Europe: Possibilities, Con-Straints and Future Perspectives

“…In addition, MPs are often mixed with heavy metals, dioxins, and polycyclic aromatic hydrocarbons [44]. Deliberate addition of flame-retardants and plasticizers to the plastic products, which subsequently become MPs, can cause hazards to soil flora and fauna [45].…”

“…Overall research on MPs pollution in agricultural soils is still in an embryonic stage. There are many knowledge gaps regarding: (a) plant ability to accumulate MPs from soil through uptake; (b) how absorbed MPs affect the plant growth and subsequently reach the food chain; (c) how soil microorganisms (bacteria and fungi) can be affected by the exposure to MPs; (d) thresholds for plastic particles to bring positive or negative impacts to the microbial activity; (e) transfer of MPs from one trophic level to another; (f) the effects of MPs on the growth, survival and metabolism of soil animals (invertebrates); (g) the bioaccumulation and biomagnification tendencies of MPs in the soil environment [45].…”

“…Depending on the origin, shape, size, and composition of MPs, it is necessary to standardize specific methods for sample collection, identification, and analysis of MPs in the organic matter-rich agricultural soils [45].…”

“…Thus, organic fertilizers may be a source of environmental MPs that should not be overlooked. Nevertheless, several questions such as ecological threats, dispersion mechanisms, and development in analytical and quantification technologies still require further studies in view of the high heterogeneity of the soil environment [45].…”

Agro-Pollutants and their Nano-Remediation from Soil and Water: A Mini-Review

“…The remediation of polluted soils and water was and still one of the critical environmental issues, which means the removal of pollutants from soil and water using different strategies such as fungi ormyco-remediation (Butu et al 2020), the cultivated plants by phytoremediation (Khan et al 2020), earthworms or vermi-remediation (Karimi et al 2020;Lacalle et al 2020;Zeb et al 2020), or soil micro-organisms by bioremediation (Kalsi et al 2020), or by using some biosorbent materials like biochar (Wang et al 2021), fly ash and organic fertilizers (Hu et al 2020), humic substances (Dong et al 2021) and nanomaterials through green remediation (Yin et al 2021) or combined remediation (Gu et al 2020). Agricultural soil could be contaminated by several pollutants such as heavy metals (Hu et al 2020), poly-and perfluoroalkyl substances (Bolan et al 2021), and microplastics (Kumar et al 2020a). This remediation could be achieved through different mechanisms such as phytoextraction , bioaugmentationand bio-stimulation (Lacalle et al 2020),immobilization (Chen et al 2020), biodegradation (Krohn et al 2021), and vermi-accumulation, vermi-transformation and vermi-degradation in case of earthworms (Zeb et al 2020).…”