چكيده لاتين
Microplastics, as plastic particles smaller than 5 mm, are recognized as emerging environmental pollutants that can have detrimental effects on terrestrial and aquatic ecosystems and pose health risks through their entry into the food chain. Compost derived from municipal solid waste, due to its heterogeneous composition and lack of an efficient separation system for organic and plastic waste, may contain significant amounts of these particles. Therefore, compost can act as a major source of microplastics transferring into agricultural soils and urban green spaces.
This study aims to identify and evaluate the abundance and diversity of microplastics in compost produced by municipal solid waste processing centers in Isfahan Province. Three compost production facilities in different cities within the province were investigated. Sampling was conducted across three seasons (autumn, winter, and spring), yielding a total of 24 samples (8 samples from each facility). Microplastics were extracted through density separation and organic matter digestion methods, followed by quantification and polymer identification using microscopic and spectroscopic techniques. Statistical analysis was performed using SPSS software to examine significant differences in the number and types of microplastics under various temporal and spatial conditions.
The results revealed that the abundance of microplastics in the studied compost samples was 46,050 ± 8,654, 38,000 ± 7,725, and 34,050 ± 7,140 particles per kilogram of dry compost for facilities S1, S2, and S3, respectively. The predominant polymers identified in facility S1 included polyethylene (40%), polypropylene (34%), polyethylene terephthalate (16%), polystyrene (7%), and polyamide and polyvinyl chloride (each 1%). In facility S2, the dominant polymers were polyethylene (40%), polypropylene (34%), polyvinyl chloride (16%), polyethylene terephthalate (7%), along with polystyrene, polyacrylonitrile, and polyamide (each 1%). In facility S3, polyolefin (34%), polyethylene (18%), polypropylene (14%), polyethylene terephthalate (9%), polyvinyl chloride (4%), polystyrene (1%), polyacrylonitrile (1%), and polyamide (1%) were the main polymer components.
The diversity and abundance of microplastics indicate multiple sources of contamination before compost production and show significantly higher levels than those reported in compost from other parts of the world. Statistical analysis also revealed that microplastic abundance was higher during warmer periods compared to colder ones, with a significant difference observed between facilities S1 and S3.
These findings underscore the need to enhance waste management processes, particularly in reducing plastic waste generation and improving source separation, to mitigate microplastic contamination in compost. Moreover, stricter quality control standards for compost production, economic tools for managing plastic waste, and advanced technologies are recommended to reduce microplastic pollution.
