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The Corona Virus disease 2019 (COVID-19) outbreak has changed the lifestyles of billions of people. Face masks, as a daily protective tool, have become a must-have item. The number of masks discarded has soared, making environmental and hygiene problems impossible to ignore. The rapid development of biodegradable materials may be one of the solutions to this issue. In this study, life cycle assessment (LCA) was used as a method to quantitatively analyze the environmental impacts of two disposable medical masks, biodegradable polylactic acid (PLA) and fossil-based polypropylene (PP). The results show that human toxicity (63.93%), acidification (39.93%), global warming potential (36.29%), and abiotic depletion (83.55%) of disposable medical masks mainly made of PLA were significantly lower than those of PP. The photochemical oxidation (4.89%) for PLA masks was slightly higher. The manufacturing cost per unit hour was 0.060 yuan (PP) and 0.0675 yuan (PLA). It was estimated that the replacement could reduce global carbon emissions by 321,392,700 tons and 466,400 tons for China. Furthermore, the process improvements in the raw material acquisition stage could maximize the benefits of carbon reduction. [Display omitted] • Feasibility of PLA as a substitute for PP in the disposable masks production verified by LCA. • The replacement can reduce annual global carbon emissions by about 321 million tons. • The manufacturing cost are 0.06 yuan/h (PP) and 0.0675 yuan/h (PLA). • Raw material acquisition stage has the greatest impact on the carbon emission. [ABSTRACT FROM AUTHOR]

• The DOC released from plastic that can be used by microorganisms in soil. • Plastic carbon participated in soil carbon cycle was confirmed. • PE plastic farmland in northwest China, 1.39 × 105 tons of excess CO 2 emissions. • Replace PE plastic film with biodegradable film, 7.5-fold more excess CO 2 emissions. Plastic film mulching is an important agricultural practice, but its accumulation in soil threatens soil health. Here, we explored the effects of plastic film on soil carbon cycling through microcosmic incubation and estimated the excess carbon dioxide (CO 2) emissions of farmland soils through Meta-analysis. The results showed that plastic film released dissolved organic carbon (DOC) into the soil, which was rapidly used by microorganisms and accelerated the decomposition of soil organic carbon (SOC), increasing CO 2 emissions. Soil moisture content and soil carbon content affected the rate of DOC release from plastic. We estimated that residual plastic film farmland in six northwest provinces of China, 1.39 × 105 tons of excess CO 2 emissions in 2020. The soil excess CO 2 emissions was influenced by polyethylene (PE) plastic concentration and soil type. Replace PE plastic film with biodegradable film, 1.05 × 106 tons of excess CO 2 emissions, 7.5 times that of PE plastics. [Display omitted] [ABSTRACT FROM AUTHOR]

Trade drives increased life-cycle carbon dioxide (CO 2) emissions and carbon leakage from plastics, increasing the environmental burden on the supply chain. Therefore, assessing the characteristics and drivers of plastic carbon emissions will help develop emission reduction strategies from a supply chain perspective. In this study, we present a model framework for life-cycle assessment, optimized input-output analysis, and structural decomposition analysis. Specifically, for the first time, we assess the life-cycle CO 2 emissions of plastics in China, the world's largest producer and consumer, and consider the input, production, consumption, and income stages of the plastic supply chain. China's plastic CO 2 emissions increased by 38.07% from 2010 to 2021 and, under a business-as-usual path, will consume 4.2–5.4% of the global carbon budget by 2050. From a supply chain perspective, each economic sector assumes different responsibilities for emissions at different stages. Despite increasing emissions, China's economic structure has potentially improved the embodied carbon leakage from the intersectoral and international trade in plastics. Furthermore, regarding socioeconomic factors, the levels of final demand (63%) and primary input (61%) dominated the increase in plastic CO 2 emissions from 2012 to 2020, and the intensity of emissions was the key to reducing emissions. The novelty of this study is that the model we proposed can solve the data limitations of the global plastics supply chain and focuses for the first time on the input and income stages and their drivers. [Display omitted] • An optimized input-output approach is applied to study plastic CO 2 emissions. • The importance of inputs and income on plastic CO 2 emissions is revealed. • Characteristics and drivers of plastic CO 2 emissions in the economic sector are investigated. • The potential impact of the economic structure on plastic-embodied carbon leakage is analyzed. • Measures to reduce CO 2 emissions from different trade supply chain perspectives are proposed. [ABSTRACT FROM AUTHOR]