Life cycle assessment of plastic waste in Suzhou, China: Management strategies toward sustainable express delivery.

The explosive growth of China's express delivery industry has greatly increased plastic waste, with low-value plastics not effectively utilized, such as PE packaging bags, which are often not recycled and end up in landfills or incinerators, causing significant resource waste and severe plastic pollution. A gate -to- grave life cycle assessment was adopted to assess the impacts of express delivery plastic waste (EDPW) management models (S1, landfill; S2, incineration; S3, mechanical pelletization), with Suzhou, China as a case. Results showed that mechanical pelletization, was the most environmentally advantageous, exhibiting a comprehensive environmental impact potential of -215.54 Pt, significantly lower than that of landfill (S1, 78.45 Pt) and incineration (S2, -121.77 Pt). The analysis identified that the end-of-life disposal and sorting stages were the principal contributors to environmental impacts in all three models, with transportation and transfer stages of residual waste having minimal effects. In terms of all environmental impact categories, human carcinogenic toxicity (HTc) emerged as the most significant contributor in all three scenarios. Specifically, S1 exhibited the most detrimental effect on human health, while S2 and S3 showed positive environmental impacts. Based on these findings, it is recommended that the application and innovation in mechanical recycling technologies be enhanced, the promotion of the eco-friendly transformation of packaging materials be pursued, and a sustainable express delivery packaging recycling management system be established. These strategies are essential for achieving more eco-friendly management of EDPW, reducing its environmental pollution, and moving towards more sustainable express delivery management practices.

Spatiotemporal variations of PM2.5 organic molecular markers in five central cities of the Yangtze River Delta, East China in autumn and winter: Implications for regional and local sources of organic aerosols.

Information on the spatiotemporal variations in the composition and sources of organic aerosols (OA) is needed to identify regional influences and to establish effective control measures. Here, 23-h PM2.5 samples were collected in five central cities of the Yangtze River Delta in eastern China, including Nanjing, Suzhou, Wuxi, Changzhou, and Zhenjiang, every three days from 2020/09/01 to 2021/02/28. Each sample was analyzed for water-soluble inorganic ions, organic carbon (OC), elemental carbon (EC), and organic molecular markers (OMMs). Generally, the major components of PM2.5, including NH4+, SO42-, NO3-, OC, and EC, exhibited similar temporal patterns across the five cities. In all OMM groups, the concentrations of PAHs, oxygenated PAHs, and secondary products of isoprene showed strong correlations (r = 0.79±0.050 - 0.93±0.028) and low coefficient of divergence (COD = 0.22±0.024 - 0.30±0.033) between sampling sites, indicating a homogeneous spatial distribution of industrial emissions and biogenic secondary OA in autumn and winter. Other OMMs showed wider r (e.g., steranes and hopanes, 0.20 - 0.80) and COD (0.26 - 0.69) ranges for all site pairs, probably due to the influence of local emissions. Based on the source apportionment results using Positive matrix factorization, the biomass burning factor dominated the contribution to OC and EC in winter and showed strong correlations (r = 0.84±0.063) between the sampling sites, indicating regional transport of emissions from biomass burning and fossil fuel combustion in the heating season. Traffic-related factors had the greatest spatial heterogeneity (r = 0.27±0.19 - 0.51±0.16) and contributed significantly to OC at their maximum levels.

Size-resolved light-absorbing organic carbon and organic molecular markers in Nanjing, east China: Seasonal variations and sources.

Owing to the potential influence of light-absorbing organic carbon (OC), also termed "brown carbon" (BrC), on the planetary radiation budget, many studies have focused on its absorption in single-sized ranges of particulate matter (PM). However, the size distribution and organic tracer-based source apportionment of BrC absorption have not been extensively investigated. In this study, size-resolved PM samples were collected using multi-stage impactors from eastern Nanjing during each season in 2017. The light absorption of methanol-extractable OC at 365 nm (Abs365, Mm-1) was determined using spectrophotometry, and a series of organic molecular markers (OMMs) was measured using a gas chromatography-mass spectrometer. Fine PM with an aerodynamic diameter <2.1 µm (PM2.1) dominated Abs365 (79.8 ± 10.4%) of the total size ranges with maxima and minima in winter and summer, respectively. The distributions of Abs365 shifted to larger PM sizes from winter to spring and summer due to lower primary emissions and increased BrC chromophores in dust. Except for low-volatility (po,*L < 10-10 atm) polycyclic aromatic hydrocarbons (PAHs), the non-polar OMMs, including n-alkanes, PAHs, oxygenated PAHs, and steranes, showed a bimodal distribution pattern. Secondary products of biogenic precursors and biomass burning tracers presented a unimodal distribution peaking at 0.4-0.7 µm, while sugar alcohols and saccharides were enriched in coarse PM. Their seasonal variations in average concentrations reflected intense photochemical reactions in summer, more biomass burning emissions in winter, and stronger microbial activity in spring and summer. Positive matrix factorization was used for the source apportionment of Abs365 in fine and coarse PM samples. Biomass burning contributed an average of 53.9% to the Abs365 of PM2.1 extracts. The Abs365 of coarse PM extracts was associated with various dust-related sources where the aging processes of aerosol organics could occur.

Seasonal Characteristics of the Chemical Composition of Fine Particles in Residences of Nanjing, China.

Indoor fine particulate matter (PM2.5) and its chemical composition is important for human exposure as people spend most of their time indoors. However, few studies have investigated the multiseasonal characteristics of indoor PM2.5 and its chemical composition in China. In this study, the chemical composition of PM2.5 samples in residences was analyzed over four seasons in Nanjing, China. Indoor water-soluble ions exhibited similar seasonal variations (winter > autumn > summer > spring) to those from outdoors (winter > autumn > spring > summer) except in summer. Whereas, indoor metallic elements exhibited a different seasonal pattern from that of outdoors. The highest concentrations of indoor metallic elements were observed in summer when the outdoor concentrations were low. The different seasonal variations of the chemical composition between indoor and outdoor PM2.5 indicated that people should consider both indoor and outdoor sources to reduce their exposure to air pollutants in different seasons. The carcinogenic risks for metallic elements were within the acceptable levels, while manganese (Mn) was found to have potential noncarcinogenic risk to humans. More attention should be paid to the pollution of Mn in the study area in the future. Moreover, the cumulative effect of noncarcinogenic PM2.5-bound elements should not be ignored.

Spatiotemporal Variations of Indoor PM2.5 Concentrations in Nanjing, China.

Indoor fine particulate matter (PM2.5) is important since people spend most of their time indoors. However, knowledge of the spatiotemporal variations of indoor PM2.5 concentrations within a city is limited. In this study, the spatiotemporal distributions of indoor PM2.5 levels in Nanjing, China were modeled by the multizone airflow and contaminant transport program (CONTAM), based on the geographically distributed residences, human activities, and outdoor PM2.5 concentrations. The accuracy of the CONTAM model was verified, with a good agreement between the model simulations and measurements (r = 0.940, N = 110). Two different scenarios were considered to examine the building performance and influence of occupant behaviors. Higher PM2.5 concentrations were observed under the scenario when indoor activities were considered. Seasonal variability was observed in indoor PM2.5 levels, with the highest concentrations occurring in the winter and the lowest occurring in the summer. Building characteristics have a significant effect on the spatial distribution of indoor PM2.5 concentrations, with multistory residences being more vulnerable to outdoor PM2.5 infiltration than high-rise residences. The overall population exposure to PM2.5 in Nanjing was estimated. It would be overestimated by 16.67% if indoor exposure was not taken into account, which would lead to a bias in the health impacts assessment.

Spatial distribution of the public's risk perception for air pollution: A nationwide study in China.

Severe air pollution problems have led to a rise in the Chinese public's concern. Risk perception is one of the most important indicators of the public's concern about air pollution. However, there existed few studies exploring the spatial distribution of risk perception. To fill the gap, psychometric paradigm methods was adopted to assess the public's risk perception of air pollution. A nationwide empirical study was conducted from December 2016 to February 2017 and 10,653 completed questionnaires were collected. According to a series of screening strategies, 9744 qualified questionnaires were included as a sample, which covered 31 China provinces (Hong Kong, Macao and Taiwan were not included in this study). We found that 45% of the respondents were dissatisfied with the current air quality, many respondents concerned a lot about air pollution (76%) and worried about the harmful consequences of being exposed to air pollution (86%). There was significant difference in the public's risk perception and attitude toward air pollution among different regions: the respondents in the northeast region, northern coastal region, eastern coastal region and Middle Yellow river region perceived higher air pollution risk and lower satisfaction with air quality than other regions; and the public's trust in the government increased from coastal regions to inland regions. In addition, the hierarchical linear model (HLM) was used to explore the effects of demographic, environmental and economic factors on public risk perception and attitude toward air pollution. Based on this, the characteristics of sensitive populations regarding air pollution were identified. What's more, we found that PM2.5 has a positive influence on perceived risk factor (PR) and can strengthen the positive correlation between PR and satisfaction with air quality (SAQ). Finally, policy implications behind these results were discussed, which can provide references and lay the foundation for policymakers and subsequent researchers.

Detection method and toxicity study of a new disinfection by-product, 2,2,4-trichloro-5-methoxycyclopenta-4-ene-1,3-dione (TCMCD), in chlorinated drinking water.

The detection method of 2,2,4-trichloro-5-methoxycyclopenta-4-ene-1,3-dione (TCMCD), a new disinfection by-product, was established and optimized. Drinking water samples from eight cities in Jiangsu Province, China, were analyzed and TCMCD was detected ranging from 42 to 171 ng/L among the water samples from the three cities. Toxicity of TCMCD was studied using the exposure of zebrafish and the human peripheral blood lymphocyte micronucleus assay. The results showed that TCMCD is fatal to zebrafish embryos and is a potential mutagen to human beings.