Microplastics are polymer-based materials with carbon as their main framework. During degradation, they release greenhouse gases such as carbon dioxide and methane. Additionally, environmental microplastics can enter plant tissues, triggering oxidative stress in plant cells, adversely affecting photosynthesis, metabolism, gene expression, and other growth parameters. This reduction in plant efficiency in sequestering and utilizing atmospheric carbon dioxide indirectly impacts global carbon cycling, exacerbating the global greenhouse effect. Furthermore, environmental microplastics significantly alter soil structure and the composition of microbial communities, affecting the emissions of greenhouse gases such as carbon dioxide, methane, and nitrous oxide, thus indirectly promoting greenhouse gas emissions. Increasing research suggests a mutual reinforcement between microplastic pollution and global climate warming, where microplastic pollution exacerbates global climate warming, and the rise in global average temperature leads to the resuspension of microplastics in sediments, intensifying microplastic pollution in the environment. This article primarily focuses on the impacts of environmental microplastic pollution on different ecosystems and the relationship between microplastic pollution and global climate warming. It summarizes the effects of microplastic pollution on greenhouse gas emissions in marine, terrestrial, and atmospheric ecosystems, as well as the mechanisms by which microplastics and climate change affect ecosystem services. By delving into the intricate connection between microplastic pollution and greenhouse gas emissions, this paper aims to raise awareness of the climate change caused by microplastic pollution and calls for further research on the impacts of microplastics on ecosystems and global climate change, with the ultimate goal of protecting ecosystems and human health. Graphical Abstract

This study was conducted to investigate the speciation, bioavailability and environmental risk of heavy metals (HMs) in chicken manure (CM) and water-washed swine manure (WSM) and their biochars produced at different pyrolysis temperatures (200 to 800 °C). As the pyrolysis temperature increased, the remaining proportion, toxicity characteristic leaching procedure (TCLP), HCl and diethylenetriamine pentaacetic acid (DTPA) of HMs gradually declined. This result proved that the speciation of HMs in chicken manure biochars (CMB) and water-washed swine manure biochars (WSMB) was influenced by pyrolysis temperature. The proportions of stable fractions were enhanced with increased pyrolysis temperature and weakened the HM validity for vegetation at 800 °C. Finally, the results of the risk assessment showed that the environmental risk of HMs in CMB and WSMB decreased with increasing pyrolysis temperature. Therefore, pyrolysis at 800 °C can provide a practical approach to lessen the initial and underlying heavy metal toxicity of CMB and WSMB to the environment.

Excessive fertilization is often applied to produce rice. To reduce nitrogen loss and improve nitrogen use efficiency (NUE), we studied the effects of application depth (surface application, 5 and 10 cm) and shape of nitrogen fertilizers (row application and deep application of large granular fertilizer) on rice growth, soil N distribution and ammonia volatilization. The results showed that grain yield, shoot biomass and total dry biomass of the treatment with N in large granular fertilizer applied at 10 cm depth were significantly higher than those of all other treatments. Moreover, compared with the surface application, the N recovery efficiency and the N agronomic efficiency of deep application treatments were enhanced by 18.1–52.3% and 35.6–95.6%, respectively. Deep application significantly increased NH₄⁺-N concentration at their fertilization points. During the growth season, N in large granular fertilizer treatments (mixed with clay to form an unusually large pellet of 1.0–1.5 cm in diameter) distributed closer to the roots, while N in other treatments, including row application treatments, was more widely distributed. Compared with the surface application, deep application significantly reduced NH3 volatilization and NH₄⁺-N concentration in surface water by 58.7–64.8% and 26.0–72.5%, respectively. Furthermore, the NH₃ volatilization from large granular treatment was 7.6–11.0% lower than that in the row application. In conclusion, applying N in large granular fertilizer at 10 cm depth reduces ammonia volatilization, and improves rice growth and grain yield, indicating improved NUE and lowered environmental risks.