Sulfur and lead isotope ratios in the atmosphere were measured at several selected sites (Harbin, Changchun, Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China and Tsukuba (Japan), to reveal regional sources characteristics over Eastern Asia. Average S isotope ratios for SO2 and sulfate in the atmosphere in China were close to those of the coals used in each region, indicating a considerable contribution of coal combustion to the sulfur compounds in the atmosphere. Most northern cities had around 5% sulfur isotope ratio, while Guiyang, a southwestern city in China, showed a considerably lower sulfur isotope ratio (about -3%) because of the unusually light sulfur isotope ratio of coals in this region. These were considerably different from the value (-1.4%) for Tsukuba (Japan). Lead isotope ratios also suggested that coal combustion considerably contributed to atmospheric lead in some cases in China. At the same time, influences by the emission of Chinese lead ores were also observed in northern cities. Seasonal variations of both sulfur and lead isotope ratios indicated the existence of a certain amount of industrial sources other than coal combustion. In addition, fractionation effect between SO2 and sulfate showed a seasonal tendency (high in winter (0-6%) and low in summer (-1-3%)), suggesting the oxidation pathway of SO2 changed seasonally.

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[1] Surface ozone (O 3 ), carbon monoxide (CO), and total and speciated reactive nitrogen compounds (NO y , NO, NO 2 , PAN, HNO 3 , and particulate NO 3 − ) were measured at Mount Waliguan (WLG; 36.28°N, 100.90°E, 3816 m above sea level (asl)) in the summer of 2006 to further understand the sources of ozone and reactive nitrogen and to investigate the partitioning of reactive nitrogen over the remote Qinghai-Tibetan Plateau. The mean mixing ratios of O 3 , CO, NO y , and daytime NO were 59 ppbv, 149 ppbv, 1.44 ppbv, and 71 pptv, respectively, which (except for NO y ) were higher than those measured from a previous campaign in summer 2003, which is consistent with more frequent transport of anthropogenic pollution from central and eastern China in the measurement period of 2006 (55%) than that of 2003 (25%). The abnormally high values of NO y observed in 2003 were suspected to be due to the positive interference from ammonia (NH 3 ) to the particular catalytic converter used in that study. Varied diurnal patterns were observed for the various NO y components. The ozone production efficiencies (DO 3 /DNO z ), which were estimated from the slope of the O 3 -NO z scatterplot, were 7.7-11.3 for the polluted plumes from central and eastern China. The speciation of reactive nitrogen was investigated for the first time in the remote free troposphere in western China. PAN and particulate NO 3 − were the most abundant reactive nitrogen species at WLG, with average proportions of 32% and 31%, followed by NO x (24%) and HNO 3 (20%). The relatively large contribution of particulate NO 3 − to NO y was due to the presence of high concentrations of NH 3 and crustal particles, which favor the formation of particulate nitrate. An analysis of backward trajectories for the recent 10 years revealed that air masses from central and eastern China dominated the airflow at WLG in summer, suggesting strong impact of anthropogenic forcing on the surface ozone and other trace constituents on the Plateau.

This paper describes the continuous measurements of atmospheric carbon dioxide at Mt. Waliguan (36°17′N, 100°54′E, 3816 m asl) in western China over the period 1994–2000. The CO2 hourly mixing ratios were segregated by horizontal wind direction/speed and vertical winds, respectively, merged by season over the entire measurement period. The short‐term variability in CO2 was examined mainly from the point of view of local winds observed at this station and isobaric back trajectory cluster‐concentration analysis as for local and long‐range transport influence, to permit the selection of hourly average data that is representative of background conditions. From the selected hourly data, daily, monthly and annual averages that are not influenced by local CO2 sources and sinks be computed by discriminating the local and regional impact on the Waliguan CO2 records. On the basis of these results, background CO2 data were then analyzed to evaluate the averaged diurnal variation, monthly mean time series, CO2 mixing ratio distribution in different seasons as well as averaged seasonal cycle. Annual mean and growth rate of CO2 at Waliguan during the period of 1991 to 2000 were further discussed by supplement with NOAA/CMDL flask air sampling records at this station and other monitoring stations located at similar latitudinal band in the Northern Hemisphere. The results from this study can provide atmospheric CO2 characteristics in Asian inland regions, and be used in other studies to improve the understanding of carbon source and sink distributions.

• 54 E, 3816 m asl) in western China over the period 1994-2000. The CO 2 hourly mixing ratios were segregated by horizontal wind direction/speed and vertical winds, respectively, merged by season over the entire measurement period. The short-term variability in CO 2 was examined mainly from the point of view of local winds observed at this station and isobaric back trajectory clusterconcentration analysis as for local and long-range transport influence, to permit the selection of hourly average data that is representative of background conditions. From the selected hourly data, daily, monthly and annual averages that are not influenced by local CO 2 sources and sinks be computed by discriminating the local and regional impact on the Waliguan CO 2 records. On the basis of these results, background CO 2 data were then analyzed to evaluate the averaged diurnal variation, monthly mean time series, CO 2 mixing ratio distribution in different seasons as well as averaged seasonal cycle. Annual mean and growth rate of CO 2 at Waliguan during the period of 1991 to 2000 were further discussed by supplement with NOAA/CMDL flask air sampling records at this station and other monitoring stations located at similar latitudinal band in the Northern Hemisphere. The results from this study can provide atmospheric CO 2 characteristics in Asian inland regions, and be used in other studies to improve the understanding of carbon source and sink distributions.