Characteristics of soil microplastics and ecological risks in the Qilian Mountains region, Northeast Tibetan Plateau

Occurrence characteristics and potential risk of microplastics under different land conditions

Microplastics (MPs) have been extensively studied in aquatic systems; however, their presence in general agricultural systems and in particular, soil still needs comprehensive understanding. This study conducted a field survey at 25 sites to investigate the abundance of MPs in agricultural soil. The MPs in these soil samples were separated using sieves and filters by the density separation method with NaCl solution (d = 1.2 g/cm3). The density of MPs in agricultural soils ranged from 1,700 items/kg to 38,800 items/kg, with an average of 11,716 ±10,726 items/kg. The black-colored MPs were found to be dominant, followed by white, purple, red, and blue. The fibers represented most of the MPs' shapes observed in this research (77.9±17.4%). MPs in agricultural soil samples were tiny particles with sizes of <1,000 µm and 1,000-2,000 µm. A significant difference was observed in the concentration of MPs in locations near and far from residential areas and manufacturing facilities. The average concentration of MPs in the soils adjacent to the residential and manufacturing facilities and near the agricultural solid waste collection sites was 21,471±12,729 items/kg and 20,188±4,403 items/kg, much higher than in distant these locations at 4,418±1,573 items/kg. These results suggest that domestic, industrial, and agricultural activities could contribute to MP pollution in agricultural soil. The ecological dangers MPs pose in terrestrial and aquatic environments have drawn much attention from the scientific community. This work represented the first effort to comprehend the ecological risk of MPs on selected samples of Vietnamese agricultural soil. According to the Pollution Load Index (PLI) values, most agricultural soil samples in this study were contaminated with MPs at hazard level IV. The potential ecological risk index (PERI) values of agricultural soil samples from nearby residential, industrial, or agricultural solid waste areas indicated a higher ecological risk.

Occurrence, sources, and ecological risk of microplastics in groundwater: Impacts by agricultural activities and atmospheric deposition.

The widespread occurrence of microplastics (MPs) in agricultural soils raises global concern, yet a systematic understanding of their national‐scale distribution and drivers remains elusive. Here, we present the first comprehensive, nationwide analysis of MPs in Chinese farmland soils, integrating abundance, morphology, and polymer data from 169 sites across 31 provinces with regional agricultural practices and soil properties. The results showed that the abundance of MPs in Chinese farmland soils ranged from 240 to 12,720 items kg −1 . Among the identified MPs, films were the predominant morphological category, accounting for 58.4%, while small‐sized particles dominated across dimensional distributions, accounting for 65.5%. Polyethylene (PE) was consistently the most prevalent polymer in all soil samples analyzed, accounting for 36.5%. The analysis results further clarified the key driving factors of MP distribution. The accumulation of MPs in soil environments resulting from local agricultural and human activities, or atmospheric deposition, may affect the transport and accumulation of small‐sized MPs. Soil properties also affected the distribution characteristics of MPs. The abundance of MPs and pH were significantly and negatively correlated ( p < 0.01). Soil electrical conductivity (EC) had a significant positive correlation with the abundance of fiber MPs ( p < 0.05), and coarse sand content was positively correlated with pellet MP counts ( p < 0.05). This study establishes that MP pollution in Chinese farmland is a spatially structured mosaic, governed by both human input and soil‐specific retention. Our findings provide an empirical basis for targeted source control (e.g., plastic mulching film management) and advance risk assessment by incorporating soil‐mediated fate processes.

Occurrence, sources, and risks of microplastics in agricultural soils of Weishan Irrigation District in the lower reaches of the Yellow River, China.

Abundance, characteristics, and ecological risks of microplastics in the riverbed sediments around Dhaka city

Although microplastic pollution is a global concern, information on the distribution of microplastics in petroleum and petrochemical urban soils is limited. In this study, we investigated the occurrence, ecological risk, and human exposure risk of microplastics in different land-use types of soil in Daqing Administrative region, a prominent petroleum and petrochemical industrial base in China. Stereoscopic microscopy and Fourier transform infrared spectroscopy (μ-FTIR) were used to study the chemical composition and distribution characteristics of microplastics. We found that the abundance of microplastics in Daqing soil ranged from 714 to 11,122 items/kg, with the highest value in educational land and the lowest in parks and green land. The dominant particle size of microplastics was < 1mm (65.7%), and the shape was mainly fiber (55.1%), with white (28.9%) and black (25.6%) as the predominant colors. The most common polymer types were rayon, polypropylene, and polyethylene. Using the potential ecological risk index (RI) and polymeric risk index (H), we found that all land-use types, except woodland (Level I), were classified into Level V of ecological risk, with the highest risk in industrial land (RI = 14,959.85, H = 588.31). The daily exposure of infants to microplastics was much higher than that of adults. These findings provide valuable data for the pollution and potential risk assessment of microplastics in urban and rural environments, suggesting the importance of taking action to minimize its harmful effects on ecological and human health. In order to control the pollution caused by microplastics, we suggest that people should reduce the unnecessary use of single-use plastic items, such as water bottles, plastic shopping bags, straws, etc. In addition, the government needs to strengthen rubbish collection to prevent plastic waste from leaking into the environment during the period from the rubbish bins to the landfills, and to build recycling systems to increase the recycling rate.

Characterization and risk assessment of microplastics in laver from the Yueqing Bay

Plastic debris (including macro-plastics, microplastics (MPs), and nanoplastics), defined as an emerging contaminant, has been proven to significantly affect soil ecosystem functioning. Accordingly, there is an urgent need to robustly quantify the pollution situation and potential sources of plastics in soils. China as the leading producer and user of agricultural plastics is analyzed as a typical case study to highlight the current situation of farmland macro-plastics and MPs. Our study summarized information on the occurrence and abundance of macro-plastics and MPs in Chinese farmland soils for the first time based on 163 publications with 728 sample sites. The results showed that the average concentration of macro-plastics, and the abundance of MPs in Chinese farmlands were 103 kg ha−1 and 4537 items kg−1 (dry soil), respectively. In addition, this study synthesized the latest scientific evidence on sources of macro-plastics and MPs in farmland soils. Agricultural plastic films and organic wastes are the most reported sources, indicating that they contribute significantly to plastic debris in agricultural soils. Furthermore, the modeling methods for quantifying macro-plastics and MPs in soils and estimating the stock and flow of plastic materials within agricultural systems were also summarized.

The occurrence and distributions characteristics of microplastics in soils of different land use patterns in Karst Plateau, Southwest China

Occurrence and distribution of microplastics in long-term biosolid-applied rehabilitation land: An overlooked pathway for microplastic entry into terrestrial ecosystems in Australia

The pollution of microplastics in sediments: The ecological risk assessment and pollution source analysis

Different functional areas and human activities significantly affect the occurrence and characteristics of microplastics in soils of the Xi'an metropolitan area

Potential ecological risk assessment of microplastics in environmental compartments in Mexico: A meta-analysis.

The large input of mulch film and organic fertilizer have led to increasingly serious microplastic pollution in farmland soil of China. In this study, the microplastic pollution of peanut farmland in Dezhou City, Shandong Province was investigated. The effects of different mulching years (0, 3, 5, and 8 years) and organic fertilizer application on the abundance, particle size, color, and shape of microplastics in farmland soil were analyzed. The results showed that the average abundances of microplastics in peanut soil were 65.33, 316.00, 1 098.67, and 1 346.34 n·kg-1, respectively, after 0, 3, 5, and 8 years of film mulching. The abundance of microplastics decreased with the increase in soil depth. The abundance of microplastics in 0-10, 10-20, and 20-30 cm topsoil was 1 076.00, 603.5, and 440.25 n·kg-1, respectively, and the abundance of microplastics increased significantly with increasing years of film mulching and organic fertilizer application (P<0.05). The particle size of microplastics in the sample plot <1 mm accounted for 77.30% of the total content, and with the increase in film mulching age, the proportion of microplastics with small particle size (<1 mm) increased significantly (P < 0.05). With the increase in soil depth, the proportion of microplastics with small particle size also gradually increased, whereas the application of organic fertilizer had no significant effect on the particle size of microplastics. The color of microplastics in the plot was mainly transparent (49.77%), followed by black (16.35%) and white (16.27%). The planting age and organic fertilizer application had no significant effect on the color of microplastics in the soil (P > 0.05), but the mulching age significantly increased the proportion of transparent microplastics. The abundance proportion of the five types of microplastics were 49.77%, 25.41%, 19.15%, 3.26%, and 2.41%, respectively. These field soil microplastics were mainly composed of polyethylene (PE), polypropylene (PP), and polystyrene (PS) polymers, accounting for 21.37%, 18.57%, and 19.77% of the total, respectively. Therefore, microplastics were widely present in the soil of the peanut field cultivated layer in Dezhou, Shandong, and the applications of mulch film and organic fertilizer were the main source. This study provides an important basis for the prevention and control of soil microplastic pollution in peanut fields.