ALBERT

Description: In the title complex, [La2(C10H10NO3)2(NO3)4(C12H8N2)4], each LaIII ion is ten-coordinated by four N atoms from two bidentate 1,10-phenanthroline ligands and by six O atoms, two from the N-acetyl-N-phenylglycinate ligands and four from two nitrate anions. Two LaIII cations, which exhibit a distorted bicapped square-antiprismatic coordination, are bridged by two N-acetyl-N-phenylglycinate ligands into a dimeric structure, generated by inversion symmetry. There is a π–π contact between the benzene rings [centroid–centroid distance = 3.409 (3) Å].

Description: In the title complex, [CrCl2(C12H8N2)2]Cl, the CrIII ion is situated on a twofold rotation axis and displays a slightly distorted octahedral CrCl2N4 coordination geometry. The Cr environment is composed of a cis arrangement of two 1,10-phenanthroline and two chloride ligands. The chloride counter-anion exhibits half-occupation and is equally disordered over two positions.

Description: In the crystal structure of the binuclear title complex, [Co(N3)2(C12H8N2)]n, each CoII cation is coordinated by two N atoms from one chelating 1,10-phenanthroline ligand and four azide ligands in a slightly distorted octahedral coordination. The two CoII cations of the binuclear complex are related by an inversion centre and are bridged by two symmetry-related azide ligands in both μ1,1 and μ1,3 modes. The μ1,3 bridging mode gives rise to an infinite one-dimensional chain along the a axis, whereas the μ1,1 bridging mode is responsible for the formation of the binuclear CoII complex.

Description: In the crystal of the title hydrated salt, C6H7N4+·C4H5O6−·0.5H2O, the biimidazole monocation, 1H,1′H-[2,2′-biimidazol]-3-ium, is hydrogen bonded, via N—H...O, O—H...O and O—H...N hydrogen bonds, to the hydrogen tartrate anion and the water molecule, which is located on a twofold rotation axis, forming sheets parallel to (001). The sheets are linked via C—H...O hydrogen bonds, forming a three-dimensional structure. There are also C=O...π interactions present [O...π distances are 3.00 (9) and 3.21 (7) Å], involving the carbonyl O atoms and the imidazolium ring, which may help to consolidate the structure. In the cation, the dihedral angle between the rings is 11.6 (2)°.

Description: In the title compound, C13H9BrClNO, the dihedral angle between the substituted benzene rings is 44.25 (11)°. There are strong intramolecular O—H...N hydrogen bonds, which generate S(6) rings, and also intermolecular Cl...Cl [3.431 (3) Å] and Br... Br [3.846 (1) Å] contacts. The crystal packing a C—H...O and C—H...π interactions.

Description: The ICTP regional climate model (RegCM3) coupled with a desert dust model is used to simulate the radiative forcing and related climate effects of dust aerosols over East Asia. Two sets of experiments encompassing the main dust producing months, February to May, for 10 years (1997–2006) are conducted and inter-compared, one without (Exp. 1) and one with (Exp. 2) the radiative effects of dust aerosols. The simulation results are evaluated against ground station and satellite data. The model captures the basic observed climatology over the area of interest. The spatial and temporal variations of near surface concentration, mass load, and emission of dust aerosols from the main source regions are reproduced by model, with the main model deficiency being an overestimate of dust amount over the source regions and underestimate downwind of these source areas. Both the top-of-the-atmosphere (TOA) and surface radiative fluxes are decreased by dust and this causes a surface cooling locally up to −1°C. The inclusion of dust radiative forcing leads to a reduction of dust emission in the East Asia source regions, which is mainly caused by an increase in local stability and a corresponding decrease in dust lifting. Our results indicate that dust effects should be included in the assessment of climate change over East Asia.

Description: This paper presents the first results of the measurements of trace gases and aerosols at three surface sites in and outside Beijing before and during the 2008 Olympics. The official air pollution index near the Olympic Stadium and the data from our nearby site revealed an obvious association between air quality and meteorology and different responses of secondary and primary pollutants to the control measures. Ambient concentrations of vehicle-related nitrogen oxides (NOx) and volatile organic compounds (VOCs) at an urban site dropped by 25% and 20–45% in the first two weeks after full control was put in place, but the levels of ozone, sulfate and nitrate in PM2.5 increased by 16%, 64%, 37%, respectively, compared to the period prior to the full control; wind data and back trajectories indicated the contribution of regional pollution from the North China Plain. Air quality (for both primary and secondary pollutants) improved significantly during the Games, which were also associated with the changes in weather conditions (prolonged rainfall, decreased temperature, and more frequent air masses from clean regions). A comparison of the ozone data at three sites on eight ozone-pollution days, when the air masses were from the southeast-south-southwest sector, showed that regional pollution sources contributed 〉34–88% to the peak ozone concentrations at the urban site in Beijing. Regional sources also contributed significantly to the CO concentrations in urban Beijing. Ozone production efficiencies at two sites were low (~3 ppbv/ppbv), indicating that ozone formation was being controlled by VOCs. Compared with data collected in 2005 at a downwind site, the concentrations of ozone, sulfur dioxide (SO2), total sulfur (SO2+PM2.5 sulfate), carbon monoxide (CO), reactive aromatics (toluene and xylenes) sharply decreased (by 8–64%) in 2008, but no significant changes were observed for the concentrations of PM2.5, fine sulfate, total odd reactive nitrogen (NOy), and longer lived alkanes and benzene. We suggest that these results indicate the success of the government's efforts in reducing emissions of SO2, CO, and VOCs in Beijing, but increased regional emissions during 2005–2008. More stringent control of regional emissions will be needed for significant reductions of ozone and fine particulate pollution in Beijing.

Description: Heterogeneous processes on dust particles are important for understanding the chemistry and radiative balance of the atmosphere. This paper investigates an intense Asian dust storm episode observed at Mount Heng (1269 m a.s.l.) in southern China on 24–26 April 2009. A set of aerosol and trace gas data collected during the study was analyzed to investigate their chemical evolution and heterogeneous photochemistry as the dust traveled to southern China. Results show that the mineral dust arriving at Mt. Heng experienced significant modifications during transport, with large enrichments in secondary species (sulfate, nitrate, and ammonium) compared with the dust composition collected at an upwind mountain top site (Mount Hua). A photochemical age "clock" (−Log10(NOx/NOy)) was employed to quantify the atmospheric processing time. The result indicates an obvious increase in the abundance of secondary water-soluble ions in dust particles with the air mass atmospheric processing time. Based on the observations, a 4-stage evolution process is proposed for carbonate-containing Asian dust, starting from fresh dust to particles coated with hydrophilic and acidic materials. Daytime-enhanced nitrite formation on the dust particles was also observed, which indicates the recent laboratory result of the TiO2 photocatalysis of NO2 as a potential source of nitrite and nitrous acid.

Description: The Project of Atmospheric Combined Pollution Monitoring over Beijing and its Surrounding Areas, was an intensive field campaign conducted over Northern China between June 2009 and August 2011 to provide a comprehensive record of ozone (O3) and nitrogen oxides (NOx) and contribute to an in-depth understanding of air pollution in Northern China and its driving forces. In this campaign, 25 stations in an air-quality monitoring network provided regional-scale spatial coverage. In this study, we analyzed the data on O3 and NOx levels obtained at 22 sites (out of 25 sites due to data availability) over Northern China between 1 September 2009 and 31 August 2010. Our goal was to investigate the O3 spatial-temporal variations and control strategy in this area. Significant diurnal and seasonal variations were noted, with the highest concentrations typically found at around 03:00 p.m. (local time) and in June. The lowest concentrations were generally found during early morning hours (around 06:00 a.m.) and in December. Compared with July and August, June has increased photochemical production due to decreased cloud cover coupled with reduced O3 loss due to less dry deposition, inducing an O3 peak appearing in June. The averaged O3 concentrations were lower in the plains area compared with the mountainous area due to the titration effects of high NOx emissions in urban areas. When the characteristics of O3 pollution in different regions were distinguished by factor analysis, we found high levels of O3 that exceeded China's National Standard throughout the plains, especially over Beijing and the surrounding areas. An integrated analysis with emissions data, meteorological data, and topography over Northern China found that the meteorological conditions were the main factors that dominated the spatial variations of O3, with the presence of abundant emissions of precursors in this area. The smog production algorithm and space-based HCHO/NO2 column ratio were used to show the O3-NOx-VOCs sensitivity and examine the control strategy of O3 over Northern China. The results show that summer O3 production in the plains and northern mountainous areas was sensitive to VOCs and NOx, respectively. The presented results are intended to provide guidance for redefining government strategies to control the photochemical formation of air pollutants over Northern China and are relevant for developing urban agglomerations worldwide.

Description: Conserving more soil water is of great importance to the sustainability of arid and semiarid orchards. Here we integrated fish-scale pits, semicircular mini-catchments for hill slope runoff collection, with mulches to test their effects on soil water storage in a 12-year-old dryland jujube orchard on the Loess Plateau of China, by using soil water measurements from April 2013 to November 2014. This experiment included four treatments: fish-scale pits with branch mulching (FB), fish-scale pits with straw mulching (FS), fish-scale pits without mulching (F), and bare land treatment (CK). Soil water was measured using the TRIME®-IPH time-domain reflectometer (TDR) tool in 20 cm intervals down to a depth of 180 cm, and was measured once every 2 weeks in the 2013 and 2014 growing seasons. The results showed that fish-scale pits with mulching were better in soil water conservation. Average soil water storage (SWS, for short) of FB at soil layer depths of 0–180 cm increased by 14.23 % (2013) and 21.81 % (2014), respectively, compared to CK, but only increased by 4.82 % (2013) and 5.34 % (2014), respectively, for the F treatment. The degree of soil water compensation, WS, was employed here to represent to what extent soil water was recharged from precipitation at the end of the rainy season relative to that at the beginning of the rainy season. A positive (negative) WS larger (lower) soil water content at the end of rainy season than at the beginning. For the treatment of FB, the values of WS over the entire soil profile were greater than 0; for the treatment of F, negative values of WS were observed in depths of 60–100 cm in both years. However, the bare land treatment showed negative values in depths of 40–180 cm. This indicated that integrating fish-scale pits with mulching could significantly increase soil water storage by increasing infiltration and decreasing evaporation, and it showed greater soil water storage and degree of soil water compensation compared to fish-scale pits alone. Since the branches used for mulching here were trimmed jujube branches, the cost of mulching materials was largely reduced. Therefore, integration of fish-scale pits with branch mulching is recommended in orchards for soil water conservation on the Loess Plateau and potentially for other regions.