separation-identification-conventional-microplastics-from-farmland

Separation and Identification of Conventional Microplastics from Farmland Soils

Microplastics (MPs) pollution in the terrestrial environment has received increasing attention over the last decade, with increasing studies describing ...

Southern University of Science and Technology

There is a major knowledge gap concerning the extent of microplastic pollution in agronomic regions of China, which represent a plastic use hotspot. In order to clarify the amendment of agronomic region and plastic film mulching mode to microplastics distribution, the characteristics of microplastics distributed in agricultural soils from three typical regions (Beijing (BJ), Shandong (SD), and Xinjiang (XJ)) with two plastic film mulching modes (greenhouse (G) and conventional field-based film mulching (M)) in China were investigated. Microplastics weight and their response to planting regions were also evaluated in this study. The result showed that the average abundance of microplastics in soils from BJ, SD, and XJ was 1.83 × 10 items kg, 4.02 × 10 items kg, and 3.39 × 10 items kg, and the estimated weight of microplastics per kg of dry soils was 3.12 mg kg, 5.63 mg kg, and 7.99 mg kg, respectively. Microplastics in farmland were mainly of small particle size (50 to 250 μm), with their abundance decreasing with increasing particle size. Among the microplastics detected, polyethylene and polypropylene were the two dominant types present, accounting for 50.0% and 19.7%, respectively. The standard total effect of planting regions on microplastic number and weight was 31.8% and 32.3%, and plastic film mulching modes (G vs. M) could explain 34.4% of the total variation of microplastic compositions with a contribution rate of 65.6% in this study. This research provides key data for an assessment of the environmental risk of microplastics and supports the development of guidelines for the sustainable use of agricultural plastic film. Further, it is necessary to quantify and assess the contribution of other different plastic sources to microplastics in soil. Big data technologies or isotope tracer techniques may be promising approaches.

Occurrence and characteristics of microplastics in soils from greenhouse and open-field cultivation using plastic mulch film.

To reveal the feedbacks and regulating mechanisms of microplastic types and doses on microbial community, a microcosm experiment was carried out with two non-degradable microplastics [polyethylene (PE) and polyvinyl chloride (PVC)] and four biodegradable microplastics [poly(butylene succinate) (PBS), polyhydroxyalkanoates (PHA), poly(butyleneadipate-co-terephthalate) (PBAT), and polypropylene carbonate (PPC)] at different levels (1 %, 7 %, and 28 %). As a result, the content of total carbon (TC), soil organic carbon (SOC), and microbial biomass carbon (MBC) (expect MBC in PBS soil) increased with increasing doses of microplastics, and increased at the lowest PE dose rate. Biodegradable microplastics created a more active ecological niche while enriching more pathogens than non-degradable microplastics. Structural equation modeling indicated that microbial diversities were in a type-dependent assembly, whereas microbial compositions were more profoundly affected by the microplastic doses, ultimately. The standardized total effect coefficient of microplastic types on bacterial and fungal diversities was - 0.429 and - 0.282, and that of doses on bacterial and fungal compositions was 0.487 and 0.336, respectively. Both microplastic types and doses significantly impacted pH, electrical conductivity, total nitrogen, TC, SOC, and MBC, subsequently inhibiting microbial diversities and stimulating microbial compositions with particular pathways. The results provide a comprehensive understanding for evaluating the potential risk of microplastics.

Regulatory path for soil microbial communities depends on the type and dose of microplastics.

This study investigates the complex dynamics of additive release from microplastics in aquatic environments under natural ultraviolet (UV) radiation, which is critical for assessing ecotoxicological impacts and developing pollution remediation strategies. We focused on release kinetics of additives (Dimethyl phthalate (DMP), Dibutyl phthalate (DBP), Di(2-ethylhexyl) phthalate (DEHP), Bisphenol A (BPA) and Decabromodiphenyl ether (BDE-209)) from polyvinyl chloride (PVC), polyethylene (PE), and acrylonitrile-butadiene-styrene (ABS) microplastics exposed to UV light, exploring the interplay between additive release, photodegradation, and microplastic aging. Initial results showed a consistent release pattern, but under UV exposure, the release became more complex due to additive degradation and changes in the microplastics' structure. Factors such as polymer type, microplastic size, additive content, and environmental conditions (UV or darkness) significantly influenced the release quantity and kinetics. UV-induced additive degradation altered the concentration gradient between the microplastic and water, while aging, marked by changes in surface chemistry and internal polymer breakdown, accelerated additive release. By applying Inner Particle Diffusion (IPD) and Aqueous Boundary Layer Diffusion (ABLD) models, we demonstrated how UV-induced degradation and aging affected key parameters like the diffusion and partition coefficients, impacting the overall release process. These insights lay the foundation for understanding the environmental risks posed by microplastic additives and developing strategies to mitigate their impact in aquatic ecosystems.

Complex release dynamics of microplastic additives: An interplay of additive degradation and microplastic aging.

As the main component of electronic products, plastics contain complex and diverse metal additives. Recycling process is not conducive to stable existence of metal additives in electronic plastics. Once the e-waste plastics enter the environment, they will continue to release harmful metals into environment after aging, causing serious hazards. This study delved into the analysis and comparison of metal content of e-waste plastics, elucidating aging process and metal leaching behavior over a 112-day natural light exposure period. The findings underscored that metal content in recycled plastics surpassed that in their new counterparts. Specifically, Ti content in new plastics remained below 100 mg/kg, while recycled plastics exhibited Ti content surpassing 100 mg/kg threshold. Throughout prolonged natural light exposure, metals such as Zn, Ba and Sb demonstrated a heightened likelihood of release from electronic plastics in comparison to other metals. The aging process during light exposure led to fragmentation of electronic plastics, accompanied by a reduction in particle size. Notably, the particle size reduction was more pronounced in poly acrylonitrile butadiene styrene (ABS) and recycled ABS, experiencing reductions of 40 µm and 85 µm, respectively. This phenomenon was attributed to the presence of polybutadiene structural units, which proved more susceptible to aging. Along with the breaking of plastics, the ABS plastics released metal species such as Pb, Cd, Ni, Al that had not been detected in other plastics solutions. The collective evidence from this study suggested that ABS and recycled ABS electronic plastics might pose a heightened potential environmental risk compared to other electronic plastics.

Ruimin Qi

School of Environmental Science and Engineering

Southern University of Science and Technology

Separation and Identification of Conventional Microplastics from Farmland Soils

Ruimin Qi

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}School of Environmental Science and Engineering

Southern University of Science and Technology

Separation and Identification of Conventional Microplastics from Farmland Soils

School of Environmental Science and Engineering