Plastic film mulching and use of wastewaters for irrigation have been common agricultural practices for over half a century in Tunisia, especially in arid regions, resulting in the undesired creation of a pathway for microplastics (MPs) to enter farmland soil. In order to assess the extent and characteristics of soil contamination by MPs in the Moknine province, an area of intensive agricultural practices, 16 farmland soil samples were collected and characterized. The total concentration of targeted MPs was 50–880 items/kg; among them, the most common MPs type being polypropylene (PP), mainly occurring as white/transparent fibers with small size (cross section <0.3 mm). SEM images of MPs surfaces revealed multiple features related to environmental exposure and degradation. ATR-FTIR spectroscopy and pyrolysis-GC/MS analyses enabled the accurate identification of MPs separated from the embedding soil micro- and macro-aggregates. Finally, contamination of the polymeric microparticles with a broad range of metals was found by ICP-MS analysis, suggesting that MPs can be vectors for transporting heavy metals in the soil and indicators of soil contamination as a result of mismanagement of industrial wastewaters.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5–2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles’ effects on different stages of crops and soil quality.

Microplastic pollution is a major global environmental problem in both aquatic and terrestrial environments. Pesticides are frequently applied to agricultural soil to reduce the effects of pests on crops, but may also affect the degradation of plastics. In this study, we generated microplastics from polyethylene (PE) film and biodegradable poly(butylene adipate-co-terephthalate) (PBAT) film and determined (1) the effect of prothioconazole on degradation of the microplastics, and (2) the adsorption and release characteristics of heavy metals (Cr, Cu, As, Pb, Ba, and Sn) by the microplastics during degradation process. Changes of surface functional groups and morphologies were measured by FTIR and SEM, while metal concentrations were determined by ICPMS. Prothioconazole was found to promote plastic degradation. PBAT degraded faster and adsorbed more heavy metals from the soil than PE. Whether the microplastics adsorb or release heavy metals depended on the metal and their concentrations. Prothioconazole inhibited the adsorption of Cr, As, Pb and Ba by microplastics, promoted the adsorption of Cu, and had no significant effect for Sn. These results can help to assess the ecological risk of microplastic pollution from plastic mulch when combined with heavy metals.

The extensive utilization of phthalate-containing products has lead to ubiquitous contamination of phthalate esters (PAEs) in various matrices. However, comprehensive knowledge of their pollution in Chinese farmland and associated risks is still limited. In this study, 15 PAEs were determined in soils from agricultural fields throughout the Mainland China. The concentrations of Σ15PAEs were in the range of 75.0–6369 μg kg−1. Three provinces (i.e., Fujian, Guangdong and Xinjiang, China) showed the highest loadings of PAEs. Bis(2-Ethylhexyl) phthalate (DEHP) was found as the most abundant component and contributed 71.5% to the ∑15PAEs. The major source of PAEs in arable soils was associated with the application of agricultural plastic films, followed by the activities for soil fertility. Furthermore, the non-cancer and carcinogenic risks of target PAEs were estimated. The hazard indexes (HIs) of PAEs in all samples were below 1 and the carcinogenic risk levels were all within 10−4. Results from this study will provide valuable information for Chinese agricultural soil management and risk avoidance.

Plastic film mulch (PFM) is a double-edged-sword agricultural technology, which greatly improves global agricultural production but can also cause severe plastic pollution of the environment. Here, we characterized and quantified the amount of macro- and micro-plastics accumulated after 32 years of continuous plastic mulch film use in an agricultural field. An interactive field trial was established in 1987, where the effect of plastic mulching and N fertilization on maize yield was investigated. We assessed the abundance and type of macroplastics (>5 mm) at 0–20 cm soil depth and microplastic (<5 mm) at 0–100 cm depth. In the PFM plot, we found about 10 times more macroplastic particles in the fertilized plots than in the non-fertilized plots (6796 vs 653 pieces/m²), and the amount of film microplastics was about twice as abundant in the fertilized plots than in the non-fertilized plots (3.7 × 10⁶ vs 2.2 × 10⁶ particles/kg soil). These differences can be explained by entanglement of plastics with plant roots and stems, which made it more difficult to remove plastic film after harvest. Macroplastics consisted mainly of films, while microplastics consisted of films, fibers, and granules, with the films being identified as polyethylene originating from the plastic mulch films. Plastic mulch films contributed 33%–56% to the total microplastics in 0–100 cm depth. The total number of microplastics in the topsoil (0–10 cm) ranged as 7183–10,586 particles/kg, with an average of 8885 particles/kg. In the deep subsoil (80–100 cm) the plastic concentration ranged as 2268–3529 particles/kg, with an average of 2899 particles/kg. Long-term use of plastic mulch films caused considerable pollution of not only surface, but also subsurface soil. Migration of plastic to deeper soil layers makes removal and remediation more difficult, implying that the plastic pollution legacy will remain in soil for centuries.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5–2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles’ effects on different stages of crops and soil quality.

High ammonia (NH₃) emissions from fertilized soil in China have led to various concerns regarding environmental safety and public health. In response to China's blue skies protection campaign, effective NH₃ reduction measures need to consider both mitigation efficiency and food security. In this context, we conducted a meta-analysis (including 2980 observations from 447 studies) to select effective measures based on absolute (AV) and yield-scaled (YSAV) NH₃ volatilization reduction potential, with the aim of establishing a comprehensive NH₃ mitigation framework covering various crop production sectors, and offering a range of potential solutions. The results showed that manipulating crop density, using an intermittent irrigation regime for paddy field rice, applying N as split applications or partially substituting inorganic fertilizer N with organic N sources could achieve reductions in AV and YSAV reduction of 10–20 %; adopting drip irrigation regimes, adding water surface barrier films to paddy fields, or using double inhibitor (urease and nitrification), slow-release or biofertilizers could achieve 20–40 % mitigation; plastic film mulching, applying fertilizer by irrigation or using controlled-release fertilizers could yield 40–60 % reduction; use of a urease inhibitor, fully substituting fertilizer N with organic N, or applying fertilizer by deep placement could decrease AV and YSAV by over 60 %. In addition, use of soil amendments, applying suitable inorganic N sources, or adopting crop rotation, intercropping or a rice-fish production model all had significant benefits to control AV. The adoption of any particular strategy should consider local accessibility and affordability, direct intervention by local/government authorities and demonstration to encourage the uptake of technologies and practices, particularly in NH₃ pollution hotspot areas. Together, this could ensure food security and environmental sustainability.

The distribution of six priority phthalic acid esters (PAEs) in suburban farmland, vegetable, orchard and wasteland soils of Tianjin were obtained with gas chromatography-mass spectrometer analysis in 2009. Results showed that total PAEs varied from 0.05 to 10.4 μg g⁻¹, with the median value as 0.32 μg g⁻¹. Di-(2-ethylhexyl) phthalate and di-n-butyl phthalate are most abundant species. PAEs concentrations for the four types of soils exhibited decreasing order as vegetable soil > wasteland soil > farmland soil > orchard soil. PAEs exhibited elevated levels in more developed regions when compared with other studies. The agricultural plastic film could elevate the PAEs contents in soils. Principal component analysis indicated the emission from cosmetics and personal care products and plasticizers were important sources for PAEs in suburban soils in Tianjin. The higher PAEs contents in wasteland soils from suburban area should be paid more attention owing to large amounts of solid wastes appeared with the ongoing urbanization.

The sorption behavior of phthalate additives in plastic and microplastic litter is an important process controlling the exposure, net health risk and ecotoxicity of these co-occurring pollutants. Plastic crystallinity and particle morphology are hypothesized to be important variables for microplastics sorption behavior, but to date there have been few direct studies to explicitly test for the influence of these parameters. To address this, in this study we explored the sorption of dibutyl phthalate (DBP) as a probe molecule to diverse polyethylene microplastics including irregularly-shaped pure polyethylene microplastics (IPPM), black plastic film microplastics (BPFM), white plastic film microplastics (WPFM), and commercial microspheres (CM), which had crystallinities ranging from 17 to 99%. Sorption kinetics for all materials could be well represented with both a pseudo-first-order (R² = 0.87–0.93) and pseudo-second-order model (R² = 0.87–0.93). Further, sorption was highly linear in the concentration range of 0.5–10 mg L⁻¹, with no greater performance from a linear sorption model (R² = 0.96–0.99) than the non-linear Freundlich or Temkin sorption models. The partition coefficient (Kd) of DBP sorption onto IPPM, BPFM, WPFM and CMs were 1974.55 L kg⁻¹, 1483.85 L kg⁻¹, 1477.45 L kg⁻¹ and 509.37 L kg⁻¹, respectively, showing a significant decrease with increasing crystallinity (r² = 0.98). The particle size of microplastics (27–1000 μm) is, however, an indecisive factor affecting their sorption behavior for DBP in this study. This study provides new insight that crystallinity plays a governing role on the sorption of phthalate from microplastic. This should be considered in future exposure studies and assessments of phthalates from plastics and microplastics.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5–2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles’ effects on different stages of crops and soil quality.