PubMed · 11509694
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D Kennedy. 2001-08-17. Going it alone.. https://doi.org/10.1126/science.293.5533.1221
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Chloroform (CHCl3) is a short-lived ozone-depleting substance not currently regulated under the Montreal Protocol. Due to the unique meteorological conditions in East Asia, CHCl3 emitted in this region has a greater potential to reach the stratosphere and contribute to ozone depletion. As an essential component of national CHCl3 emissions, southeastern China has attracted increasing attention. However, long-term observational data in this region remain relatively scarce, with no updates since 2020. In this study, we continuously measured atmospheric CHCl3 concentrations at a remote monitoring station in southeastern China from 1 June 2023 to 31 May 2025. Frequent concentration enhancements were observed during the monitoring period, with mixing ratios ranging from 9.3 to 134.1 ppt and an average value of 36.8 ± 19.7 ppt. Back-trajectory analysis indicated that air masses associated with elevated CHCl3 levels primarily originated from coastal industrial provinces in eastern China. Using the Potential Source Contribution Function and Concentration Weighted Trajectory methods, we identified the Yangtze River Delta (Jiangsu, Anhui, and Zhejiang Provinces) and Jiangxi Province as dominant source regions. Emissions of CHCl3 in southeastern China were estimated using the Tracer Ratio Method to be approximately 30.1 ± 5.3 Gg/yr from 2023-06-01 to 2025-05-31, indicating overall stability relative to earlier estimates and no apparent upward trend. These findings provide updated insights into the current status of CHCl3 emissions in southeastern China and highlight the need for continued monitoring and emission assessment of CHCl3 in East Asia, given its unregulated status and implications for ozone layer recovery.
The wet, dry and total atmospheric depositions of some metals (Al, Cd, Cr, Cu, Fe, Na, Pb and Zn) were sampled at two sites and atmospheric fallout fluxes were determined for these locations. This work, led by two different research groups, allowed to reach two main goals: to define a simple analytical procedure to secure accurate shipboard sampling and analysis of atmospheric deposition, and to assess anthropogenic impacts of heavy metals to the environment. The first step about the validation step showed that the prevalent deposition type was dry deposition which represents 40, 60 and 80% for Cd, Cu and Pb, respectively. This prevalence of dry deposition in total atmospheric fallout supported the necessity of funnel wall rinsing which contains 30, 50 and 40% of collected Cd, Cu and Pb, respectively. Moreover, the reproducibility of atmospheric deposition collection was determined. The second step was performed by comparing two sampling sites. A rural sampling site, situated in Morvan's regional park (250 km south-east of Paris), was chosen for its isolation from any local and regional contamination sources. Fluxes obtained in this area were compared with those obtained at an urban site (Créteil, suburb of Paris) allowing comparison between urban and rural areas and demonstrating the impact of anthropogenic activities on atmospheric deposition of Cr, Cu and Pb.
This paper presents an assessment of the air quality for the principal cities in developed and developing countries. Part of the vast and widely dispersed information on air quality that is available at this time on the Internet was compiled, thus making possible a comprehensive evaluation of the tendencies that emerged at the end of the 20th century. Likewise, these values are compared to the air quality thresholds recommended by two international organizations: guideline levels of the World Health Organization (WHO) and limit values of the European Union (EU), in order to determine air quality concentration levels in large cities around the world. The current situation of air quality worldwide indicates that SO(2) maintains a downward tendency throughout the world, with the exception of some Central American and Asian cities. NO(2) maintains levels very close to the WHO guideline value around the world. For particulate matter, it is a major problem in almost all of Asia, exceeding 300 microg/m(3) in many cities. Ozone shows average values that exceed the selected guideline values in all of the analyses demonstrating that it is a global problem. In general, the worldwide trend is to a reduction in the concentrations of pollutants because of the increasingly strong restrictions which local governments and international organizations impose. However, in poor countries and those with low average incomes, concentrations of air pollutants remain high and the trend will be the elevation of their ground levels as they develop, making the problem even worse.