Seasonal variation and origins of volatile organic compounds observed during 2 years at a western Mediterranean remote background site (Ersa, Cape Corsica)

An original time series of about 300 atmospheric measurements of a wide range of volatile organic compounds (VOCs) was obtained at a remote Mediterranean station on the northern tip of Corsica (Ersa, France) over 25 months from June 2012 to June 2014. This study presents the seasonal variabilities of 35 selected VOCs and their various associated sources. The VOC abundance was largely dominated by oxygenated VOCs (OVOCs) along with primary anthropogenic VOCs with a long lifetime in the atmosphere. VOC temporal variations were then examined. Primarily of local origin, biogenic VOCs exhibited notable seasonal and interannual variations, related to temperature and solar radiation. Anthropogenic compounds showed increased concentrations in winter (JFM months) followed by a decrease in spring/summer (AMJ/JAS months) and higher winter concentration levels in 2013 than in 2014 by up to 0.3 µg m−3 in the cases of propane, acetylene and benzene. OVOC concentrations were generally high in summertime, mainly due to secondary anthropogenic/biogenic and primary biogenic sources, whereas their lower concentrations during autumn and winter were potentially more influenced by primary/secondary anthropogenic sources. Moreover, an apportionment factorial analysis was applied to a database comprising a selection of 14 individual or grouped VOCs by means of the positive matrix factorization (PMF) technique. A PMF five-factor solution was taken on. It includes an anthropogenic factor (which contributed 39 % to the total concentration of the VOCs selected in the PMF analysis) connected to the regional background pollution, three other anthropogenic factors (namely short-lived anthropogenic sources, evaporative sources, and long-lived combustion sources, which together accounted for 57 %) originating from either nearby or more distant emission areas (such as Italy and south of France), and a local biogenic source (4 %). Variations in these main sources impacting VOC concentrations observed at the Ersa station were also investigated at seasonal and interannual scales. In spring and summer, VOC concentrations observed at Ersa were the lowest in the 2-year period, despite higher biogenic source contributions. During these seasons, anthropogenic sources advected to Ersa were largely influenced by chemical transformations and vertical dispersion phenomena and were mainly of regional origins. During autumn and winter, anthropogenic sources showed higher contributions when European air masses were advected to Ersa and could be associated with potential emission areas located in Italy and possibly more distant ones in central Europe. Higher VOC winter concentrations in 2013 than in 2014 could be related to contribution variations in anthropogenic sources probably governed by their emission strength with external parameters, i.e. weaker dispersion phenomena and the pollutant depletion. High-frequency observations collected during several intensive field campaigns conducted at Ersa during the three summers 2012–2014 confirmed findings drawn from bi-weekly samples of the 2-year period in terms of summer concentration levels and source apportionment. However, they also suggested that higher sampling frequency and temporal resolution, in particular to observe VOC concentration variations during the daily cycle, would have been necessary to confirm the deconvolution of the different anthropogenic sources identified following the PMF approach. Finally, comparisons of the 25 months of Ersa observations with VOC measurements conducted at 17 other European monitoring stations highlighted the representativeness of the Ersa station for monitoring seasonal variations in VOC regional pollution impacting continental Europe. Nevertheless, VOC winter concentration levels can significantly vary between sites, pointing out spatial variations in anthropogenic source contributions. As a result, Ersa concentration variations in winter were more representative of VOC regional pollution impacting central Europe. Moreover, interannual and spatial variations in VOC winter concentration levels were significantly impacted by synoptic phenomena influencing meteorological conditions observed in continental Europe, suggesting that short observation periods may reflect the variability of the identified parameters under the specific meteorological conditions of the study period.

Snow pollution in the water area of the world heritage lake

The monitoring of the snow cover of the water area and the surrounding territory of Lake Baikal showed that the pollution of the area caused by the local sources spreads dozens of kilometers depending on the prevailing wind direction and reaches regional proportions in the central zone of Baikal’s basin. Air and snow pollution of the lake’s water area has been detected near the littoral residential zones and in the estuary of the Selenga River. The research also showed a small increase in the regional pollution for the past 5years (by a factor of 1,1 - 2 depending on a pollutant). However, according to the data gathered for the last 15years, the pollution decreased by a factor of two at the end of the 1990s and at the beginning of the 2000s due to the decline in manufacturing output.

Seasonal variation and origins of volatile organic compounds observed during two years at a western Mediterranean remote background site (Ersa, Cape Corsica)

An original time series of about 300 atmospheric measurements of a wide range of volatile organic compounds (VOCs) has been obtained at a remote Mediterranean station on the northern tip of Corsica Island (Ersa, France) over 25 months from June 2012 to June 2014. This study presents the seasonal variabilities of 25 selected VOCs, and their various associated sources. The VOC speciation was largely dominated by oxygenated VOCs (OVOCs) along with primary anthropogenic VOCs having a long lifetime in the atmosphere. VOC temporal variations are then examined. Primarily of local origin, biogenic VOCs exhibited notable seasonal and interannual variations, related to temperature and solar radiation ones. Anthropogenic compounds have shown an increasing concentration trend in winter (JFM months) followed by a decrease in spring/summer (AMJ/JAS months), and different concentration levels in winter periods of 2013 and 2014. OVOC concentrations were generally higher in summertime, mainly due to secondary and biogenic sources, whereas their concentrations during fall and winter were potentially more influenced by anthropogenic primary/secondary sources. Moreover, an apportionment factorial analysis was applied to a database comprising a selection of 14 primary individual or grouped VOCs by means of the positive matrix factorization (PMF) technique. A PMF solution composed of 5 factors was taken on. It includes a biogenic factor (which contributed 4 % to the total VOC mass), three anthropogenic factors (namely short-lived anthropogenic sources, evaporative sources, and long-lived combustion sources; which together accounted for 57 %), originating from either nearby or more distant emission areas (such as Italy and south of France); and a remaining one (39 %) connected to the regional background pollution. Variations in these main sources impacting VOC concentrations observed at the receptor site are also investigated at seasonal and interannual scales. In spring and summer, VOC concentrations observed at Ersa were the lowest in the 2-yr period, despite higher biogenic source contributions and since anthropogenic sources advected to Ersa were largely influenced by chemical transformations and vertical dispersion phenomena and were mainly of regional origins. During fall and winter, anthropogenic sources showed higher accumulated contributions when European air masses were advected to Ersa and could be associated to potential emission areas located in Italy and possibly more distant ones in central Europe. Higher VOC concentrations during winter 2013 compared to winter 2014 ones could be related to anthropogenic source contribution variations probably governed by emission strength of the main anthropogenic sources identified in this study together with external parameters, i.e. weaker dispersion phenomena and pollutant depletion. High frequency observations collected during several intensive field campaigns conducted at Ersa during the three summers 2012–2014 confirmed findings from bi-weekly samples in terms of summer concentration levels and source apportionment. However, they suggest that higher sampling frequency and temporal resolution, in particular to observe VOC concentrations variation during the daily cycle, are needed to confirm the deconvolution of the different anthropogenic sources identified by PMF approach. Finally, comparisons of the 25 months of observations at Ersa with VOC measurements conducted at 17 other European monitoring stations highlight the representativeness of the Ersa background station for monitoring seasonal variations in VOC regional pollution impacting continental Europe. Nevertheless, winter VOC concentration levels can significantly vary between sites, pointing out spatial variations in anthropogenic source contributions. As a result, Ersa concentration variations in winter were more representative of VOC regional pollution impacting central Europe. Interannual and spatial VOC concentration variations in winter were also significantly impacted by synoptic phenomena influencing meteorological conditions observed in continental Europe, suggesting that short observation periods may reflect the variability of the identified parameters under the specific meteorological conditions of the studied period.

Leading small groups in China's inter-city governmental cooperation

PurposeOver the past several decades, there has been an increasing trend towards inter-city cooperation, which is an efficient policy option to deal with the challenges from globalization, regionalization and the externalities resulting from urban entrepreneurialism. Specific to China, the city governments, which mainly refer to prefecture-level and county-level governments, have also made many attempts to cooperate with respect to their local economic development and public affairs. Nevertheless, the results of these initiations to cooperate vary to a great extent. Based on a review of regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu. The findings demonstrate that China's idiosyncratic institutional background has a significant impact on the shaping of inter-city cooperation. For the most part, leading small groups (LSGs) and their leadership property tend to determine the effectiveness of inter-city cooperation.Design/methodology/approachTo examine the effect of the LSGs, we categorize them into three types, groups with strong leadership, weak leadership and self-forming leadership. Through reviewing regional pollution governance in the Xiaoqing River area, tourism cooperation initiatives at Weishan Lake and transport integration between Jinan and Laiwu, we try to probe the role of leading groups in the settlement of cross-administrative border issues.FindingsBased on these three cases, the conclusion can be drawn that the leadership type of the LSG can exert an important influence on the efficiency of inter-city cooperation. If there is a leader with a higher administrative rank or authority, the cooperation can be quite efficient. Otherwise, the cooperative ending might be very negative. In terms of the operation principle, we can infer that even though the cities are always self-development oriented, the leader with higher authority or a strong coordinating capacity can convince and persuade the city leaders to overcome their self-centered behavior template and boost the cooperation to March on smoothly. Also, it means that the LSG is constrained by its personalistic characteristic. Key command derives from the person who chairs the LSG other than specific rules and norms. If the lead of the LSG leaves his position, the cooperation might just become paralyzed. From this point of view, the lack of legal basis remains to be the LSGs' significant deficiency and the future reform should attach more importance to the legalization of the LSGs so the operation of LSGs can be more standard and stable.Originality/valueMany scholars have proposed their own theoretical models to explain the reason some cities successfully and effectively form cooperative relations, while the other cities do not. However, their models do not consider the idiosyncratic context of China or, how and to which extent LSGs can promote cooperation. Therefore, this paper seeks to probe which path in the context of China cities usually follows in the formation of joint efforts, and what role LSGs play in enabling cities to cooperate.