Characterization of atmospheric trace gases and particle matters in Hangzhou, China

Abstract

<p><strong>Abstract.</strong> The Yangtze River Delta (YRD) is one of the most densely populated regions in China with severe air quality issues, which has not been fully understood. Thus, in this study, based on one-year (2013) continuous measurement at a National Reference Climatological Station (NRCS, 30.22° N, 120.17° E, 41.7 m a.s.l.) in the center of Hangzhou in the YRD, we investigated the seasonal characteristics, interspecies relationships, and the local emissions and the regional potential source contributions of trace gases (including O<sub>3</sub>, NO<sub>x</sub>, NO<sub>y</sub>, SO<sub>2</sub> and CO) and particulate matters (PM<sub>2.5</sub> and PM<sub>10</sub>). Results revealed severe two-tier air pollution (photochemical and haze pollution) occurred in this region, with frequent exceedances in O<sub>3</sub> (38 days) and PM<sub>2.5</sub> (62 days). O<sub>3</sub> and PM<sub>2.5</sub> both exhibited distinct seasonal variations with reversed patterns: O<sub>3</sub> reaching a maximum in warm seasons (May and July) but PM<sub>2.5</sub> in cold seasons (November to January). The overall results from interspecies correlation indicated a strong local photochemistry favoring the O<sub>3</sub> production under a volatile organic compound (VOC)-limited regime, whereas it moved towards an optimum O<sub>3</sub> production zone during warm seasons, accompanying with a formation of secondary fine particles under high O<sub>3</sub>. The emission maps of PM<sub>2.5</sub>, CO, NO<sub>x</sub>, and SO<sub>2</sub> demonstrated that local emissions were both significant for these species on seasonal scale. The contributions from the regional transports among inland cities (Zhejiang, Jiangsu, Anhui, and Jiangxi Province) on seasonal scale were further confirmed to be crucial to air pollution at NRCS site by using the backward trajectories simulations. Air masses transported from Yellow Sea, East Sea, and South Sea were also found to be highly relevant to the elevated pollutants, especially for NO<sub>x</sub> and O<sub>3</sub>. Case studies of photochemical pollution (O<sub>3</sub>) and haze (PM<sub>2.5</sub>) episodes both suggested the combined importance of local atmospheric photochemistry and synoptic conditions during the accumulation (related with anticyclones) and dilution process (related with cyclones). This study supplements a general picture of the air pollution state in the YRD region, specifically elucidates the role of local emission and regional transport, and interprets the physical and photochemical processes during haze and photochemical pollution episodes. Moreover, this work suggests that cross-regional control measures are crucial to improve air quality in the YRD region, and further emphasizes the importance of local thermally induced circulation on air quality.</p>

Review of Desert Mobility Assessment and Desertification Monitoring Based on Remote Sensing

“…These methods typically require surface measurements of the imagery transits and the consideration of factors such as terrain relief to accurately correct for atmospheric and sensor effects. However, meeting the aforementioned conditions is often challenging for most remote sensing images available today, thus resulting in their complexity [43]. Based on the performance of the atmospheric correction processor ATCOR, Pflug et al [44] combined two data sources and ensured the consistent quality of the atmospheric correction to obtain a denser time series.…”

Study on the Spatial Distribution Characteristics and Poverty Inducements of Poverty-Stricken Villages in Henan Province

“…In terms of research content, they have analyzed the spatial geographical distribution characteristics of poverty villages in their administrative regions [7,8], the causes of poverty [9,10], and the treatment methods [11][12][13]. The spatial and geographical distribution characteristics of poverty villages have focused on the analysis of local poverty distribution patterns in provinces [14], cities [15], counties [16], and concentrated poverty areas [17,18]. Some scholars have analyzed the distribution characteristics of poverty-stricken villages in karst landforms and mountainous regions from the perspective of geomorphology and regional resources.…”