Phenotypic plasticity of the leaves can interfere with the plant sensitivity to ozone (O3) toxic effect. This study aimed to assess whether the leaf structure of Ipomoea nil changes due to climatic variations and whether these changes affect the species' sensitivity. Field exposures, in different seasons (winter and spring) were made. The leaves that developed during the winter were thinner, with a lower proportion of photosynthetic tissues, higher proportion of intercellular spaces and lower density and stomatal index compared to those developed during the spring. The temperature and relative humidity positively influenced the leaf thickness and stomatal index. The visible injuries during winter were positively correlated with the palisade parenchyma thickness and negatively correlated with the percentage of spongy parenchyma; during the spring, the symptoms were positively correlated with the stomatal density. In conclusion, the leaf structure of I. nil varied among the seasons, interfering in its sensitivity to O3.

Atmospheric PM10 were measured for 12 months at 18 sites along a 2500 km profile across northern China. Annual mean PM10 concentrations in urban, rural village, and rural field sites were 180 ± 171, 182 ± 154, and 128 ± 89 μg/m3, respectively. The similarities in PM10 concentrations between urban and rural village sites suggest that strong localized emissions and severe contamination in rural residential areas are derived from solid fuels combustion in households. High PM10 concentrations in Wuwei and Taiyuan were caused by either sandstorms or industrial activities. Relatively low PM10 concentrations were observed in coastal areas of Dalian and Yantai. Particulate air pollution was much higher in winter and spring than in summer and fall. Multiple regression analysis indicates that 35% of the total variance can be attributed to sandstorms, precipitation and residential energy consumption. Over 40% of the measurements in both urban and rural village areas exceeded the national ambient air quality standard.

A detailed investigation was conducted into the concentration of polycyclic aromatic hydrocarbons (PAHs) associated with PM10 particles collected during 2012 in an urban area in Cordoba, Argentina. Their composition was studied and the lifetime lung cancer risk resulting from exposure to total and individual PAHs was estimated. Samples of PM10 were collected daily on fiber glass filters with PAHs being extracted with methylene chloride and analyzed by HPLC. Mean PAH concentrations were higher during autumn and winter. In contrast, during warm months, high ambient temperature and wind speed contributed to a decrease in the PAH ambient concentrations. The PAH levels found in the present study were within the range of those reported in other polluted urban areas. However risk factors calculated for exposure to individual and cumulative PAHs exceeded the carcinogenic benchmark level of 1 × 10−6 early in childhood, implying that these PAH concentrations represent a serious risk to public health.

Excessive nitrogen input in natural ecosystems is a major threat to biodiversity. A coastal dune area near Amsterdam in the Netherlands suffers from high atmospheric nitrogen deposition affecting sensitive habitats such as fixed coastal dunes with herbaceous vegetation (‘grey dunes’). To mitigate its effect year round grazing was applied from 2007 until 2012. In winter, when natural food supply is low, the cattle received supplementary hay that caused additional inputs of nitrogen. Estimates based on nitrogen contents of hay, as well as of manure, showed the input through winter feeding (c. 3–14 kg N ha−1.y−1) is in the same order of magnitude as both the actual deposition (c. 17 kg N ha−1.y−1) and the critical load for a number of herbaceous habitat types (10–15 kg N ha−1.y−1). Locally, the effect of winter feeding adds to the effect of nitrogen redistribution within the area caused by the cattle's terrain usage. We conclude that winter feeding may aggravate effects of atmospheric nitrogen deposition.

The chemical composition of Beijing aerosol was measured during summer and winter. Two distinct episodes were identified. Water-soluble potassium (K+) increased significantly during the firework episode in winter with an episode to non-episode ratio of 4.97, whereas the biomass burning (BB) episode in summer was characterized by high episode to non-episode ratios of levoglucosan (6.38) and K+ (6.90). The BB and firework episodes had only a minor influence on the water-soluble OC (organic carbon) to OC ratio. Based on separate investigations of episode and non-episode periods, it was found that: (i) sulfate correlated strongly with both relative humidity and nitrate during the typical winter period presumably indicating the importance of the aqueous-phase oxidation of sulfur dioxide by nitrogen dioxide, (ii) oxalate and WSOC during both winter and summer in Beijing were mainly due to secondary formation, and (iii) high humidity can significantly enhance the formation potential of WSOC in winter.

Carbon monoxide (CO) emissions in China in 2005–2010 were estimated by inversion, using the Green's function method from vertical CO profiles derived from MOPITT Version 5 satellite data and a tagged CO simulation, and validated with independent in situ observations from the World Data Centre for Greenhouse Gases. Modeling with a posteriori emission successfully reproduced CO outflow from the continent to the East China Sea, Sea of Japan, and Japanese islands during winter and spring, and compensated for underestimates in central and eastern China in summer. A posteriori emissions showed large seasonal variations in which December and March emissions were on average 23% larger than August emissions, consistent with other studies. Estimated Chinese CO emissions were 184.4, 173.1, 184.6, 158.4, 157.4, and 157.3 Tg/year for 2005–2010, respectively. The decrease after 2007 is partly attributed to Chinese socioeconomic conditions and improved combustion efficiency.

Tropospheric O3 is a strong oxidant that may affect vegetation and human health. Here we report on the O3 fluxes from a poplar plantation in Belgium during one year. Surprisingly, the winter and autumn O3 fluxes were of similar magnitude to ones observed during most of the peak vegetation development. Largest O3 uptakes were recorded at the beginning of the growing season in correspondence to a minimum stomatal uptake. Wind speed was the most important control and explained 44% of the variability in the nighttime O3 fluxes, suggesting that turbulent mixing and the mechanical destruction of O3 played a substantial role in the O3 fluxes. The stomatal O3 uptake accounted for a seasonal average of 59% of the total O3 uptake. Multiple regression and partial correlation analyses showed that net ecosystem exchange was not affected by the stomatal O3 uptake.

Pristine mountains are ideal settings to study transport and behavior of persistent organic pollutants (POPs) along gradients of climate and land cover. The present work investigated the concentrations and patterns of 28 organochlorine pesticides (OCPs), 25 polychlorinated biphenyl (PCBs), 13 polybrominated diphenyl ethers (PBDEs), and 3 hexabromocyclododecane (HBCDs) isomers in the air of the Shergyla Mountain, southeastern Tibetan Plateau. Endosulfan І, hexachlorobenzene, pentachlorobenzene, hexachlorocyclohexanes and dichlorodibenzotrichloroethane and its degradation products (DDTs) were the predominant compounds while PBDEs and HBCDs showed the lowest background concentrations. Most of the target POPs had significantly higher concentrations in summer than those in winter. Increasing trends of the concentrations of DDTs and endosulfan were found with increasing altitude on the western slope in the Shergyla Mountain. Potential forest filter effect was observed based on the lower air concentrations of the target POPs in the forest than the ones out of the forest.

Atmospheric pollution has become a significant challenge in Beijing metropolitan region, China. In this study, wavelet analysis and gray analysis were proposed to explore the temporal characteristics of particulate matter (PM10) and its relationships with meteorological factors during 2001–2012. The analysis indicated that air quality had got better significantly over the last decade. It was clearly interannual, seasonal, and monthly variation of atmospheric pollution, which represented that the air quality was the worst in spring, and got better in summer, subsequently tended to be more serious in autumn and winter. Generally atmospheric pressure was the most important meteorological feature influencing on PM10, followed by relative humidity and wind speed. However, the dominant meteorological factors influencing the atmospheric pollution were different in the four seasons. The results suggest that urban design and effective measures based on the relationship between meteorological factors and PM10 would be effective for improving atmospheric pollution.

Fifteen polycyclic aromatic hydrocarbons (PAHs) in PM2.5 samples collected in five different cities (Hong Kong (HK), Guangzhou (GZ), Xiamen (XM), Xi'an (XA) and Beijing (BJ)) in China in the winter 2012–12 were analyzed by gas chromatography-mass spectrometry. The biological effects of organic extracts were assayed using the human bronchial epithelial cells BEAS-2B. All sixteen priority PAHs can be found in the PM2.5 samples of XA and BJ, but not in HK, GZ and XM, demonstrating the differential spatial source and distribution of PAHs. Our results showed that the total PAHs ranged from 3.35 to 80.45 ng/m3 air, leading by BJ, followed by XA, XM, GZ and HK. In the cell culture study, transcript levels of pro-inflammatory cytokine interleukin-6 (IL-6), CYP1A1 and CYP1B1 were found to be induced in the treatment. The cells exposed to extracts from XA and BJ demonstrated significant migratory activities, indicating a sign of increase of tumorigenicity.