Regional atmospheric pollutant transport mechanisms over the North China Plain driven by topography and planetary boundary layer processes Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Jiannong Quan, Youjun Dou, Xiujuan Zhao, Quan Liu, Zhaobin Sun, Yubing Pan, Xingcan Jia, Zhigang Cheng, Pengkun Ma, Jie Su, Jinyuan Xin, Yangang Liu Abstract Comprehensive measurements were conducted in winter 2018 and combined with RMPAS-Chem model simulations to analyze the regional transport mechanisms of atmospheric pollutants over the North China Plain. The instruments used consisted of four Vaisala CL51 ceilometers for planetary boundary layer (PBL) heights and aerosol backscatter profiles, two wind profilers, one radiosonde for the profiles of meteorological variables, and an instrumented King-Air 350 aircraft for the profiles of atmospheric pollutants and meteorological variables. Additionally, observations from Environmental Protection Bureau stations were also analyzed, including hourly concentrations of surface PM2.5, SO2, NO2, CO, and O3. The results suggest that regional atmospheric pollutant transport is driven by a combination of topography and PBL processes. First, a mountain-induced vertical vortex forms over downwind regions; this elevates ground pollutants to form an elevated pollutant layer (EPL) at an altitude of 1.4–1.7 km. The EPL is then transported to Beijing via an enhanced southerly wind. Finally, the pollutants in the EPL are transported downward to the surface through PBL processes.

Adaptive spatial sampling design for environmental field prediction using low-cost sensing technologies Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Eun-Hye Yoo, Andrew Zammit-Mangion, Michael G. Chipeta Abstract The last decade has seen an explosion in data sources available for monitoring and prediction of environmental phenomena. While several inferential methods have been developed to make predictions on the underlying process by combining these data, an optimal sampling design for additional data collection in the presence of multiple heterogeneous sources has not yet been developed. Here, we provide an adaptive spatial design strategy based on a utility function that combines both prediction uncertainty and risk-factor criteria. Prediction uncertainty is obtained through a spatial data fusion approach based on fixed rank kriging that can tackle data with differing spatial supports and signal-to-noise ratios. We focus on the application of low-cost portable sensors, which tend to be relatively noisy, for air pollution monitoring, where data from regulatory stations as well as numeric modeling systems are also available. Although we find that spatial adaptive sampling designs can help to improve predictions and reduce prediction uncertainty, low-cost portable sensors are only likely to be beneficial if they are sufficient in number and quality. Our conclusions are based on a multi-factorial simulation experiment, and on a realistic simulation of pollutants in the Erie and Niagara counties in Western New York.

Dynamics and mechanisms of volatile organic compound exchanges in a winter wheat field Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): A. Bachy, M. Aubinet, C. Amelynck, N. Schoon, B. Bodson, P. Delaplace, A. De Ligne, A. Digrado, P. du Jardin, M.-L. Fauconnier, A. Mozaffar, J.-F. Müller, B. Heinesch Abstract The understanding of biogenic volatile organic compound (BVOC) exchanges has become a key scientific issue because of their high reactivity and their impact in the atmosphere. However, so far, few studies have focused on BVOCs exchanged by agricultural species, and in particular by winter wheat, despite this species being the leading worldwide crop in terms of harvested area. This study for the first time investigated BVOC exchanges from winter wheat during most developmental stages of the plant. Fluxes were measured in Belgium at the ecosystem-scale using the disjunct eddy covariance by mass scanning technique, and a proton-transfer-reaction mass spectrometer for BVOC ambient mixing ratio measurements. As is usually observed for crops and grasses, the winter wheat field emitted mainly methanol, although bi-directional exchanges were observed. The second most exchanged compound was acetic acid which was captured during the entire growing season. Bi-directional exchanges of acetaldehyde and acetone were also reported. Terpene exchanges were 22 times smaller than oxygenated VOC (OVOC) exchanges. For all compounds, the exchanges were the most pronounced at the end of the growing season, i.e., under warm, dry and sunny conditions. Senescence-induced emissions were furthermore observed for methanol and acetaldehyde. For all investigated OVOCs, the exchanges very likely originated from both the soil and the plants. Despite their mixed origin, the MEGAN (Model of Emissions of Gases and Aerosols from Nature) v2.1 up-scaling model could adequately reproduce the methanol, acetaldehyde and acetone exchanges measured at this site during the mature and senescence phases of the plant, when the standard emission factor and the leaf age factor were adapted based on the measurements. In contrast, the model failed to reproduce the measured acetic acid exchanges. When the standard emission factor values currently assigned in MEGAN were applied, however, the exchanges were largely over-estimated for all compounds.

Chemical nature of zinc in size fractionated particulate matter from residual oil combustion - A comparative study Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Sidhartha Pattanaik, Frank E. Huggins Abstract Although zinc is ubiquitous in ambient particulate matter (PM), exposure to size fractionated residual oil fly ash (ROFA) PM is of particular concern due to several studies implicating particle zinc in mortality, adverse respiratory and cardiac effects. The lack of zinc speciation data is an impediment to our understanding of the biological mechanism of Zn induced toxicity. ROFA PM2.5+ samples (i.e. particle with aerodynamic diameter >2.5 μm) are prepared in a small 732 kW practical fire tube boiler by combusting one No. 5 and three No. 6 residual oil(s) of varying sulfur and ash contents. The combined X-ray absorption spectroscopy and selective extraction method is used to determine the Zn speciation in PM2.5+ samples. The Zn speciation in ROFA PM2.5 (i.e. particle with aerodynamic diameter <2.5 μm) samples, reported earlier, is included here for comparison purposes. The data show that zinc sulfate is predominant in both fractions. In addition, an appreciable amount of zinc phosphate was detected in the PM2.5 fraction. The insoluble zinc forms in both the fractions are identified as Zn-sorbed-ferrihydrite and zinc sulphide. The variation of Zn speciation across different size fractions has implication on the bioavailability and toxicity of Zn. Such source specific speciation data are needed for developing source inventories, and for amending existing regulations/framing new regulations for different size fractions. Graphical abstract

Effects of European emission reductions on air quality in the Netherlands and the associated health effects Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Guus J.M. Velders, Rob J.M. Maas, Gerben P. Geilenkirchen, Frank A.A.M. de Leeuw, Norbert E. Ligterink, Paul Ruyssenaars, Wilco J. de Vries, Joost Wesseling Abstract Policies implemented in Europe since the 1970s to improve the air quality have resulted in decreases in emissions in many countries with corresponding reductions in concentrations of sulphur dioxide (SO2), nitrogen dioxide (NO2) and particulate matter (PM). We report here how much the air quality and associated health effects in the Netherlands have improved since 1980 and which countries, sectors and policies are responsible for this. To quantify the effects of emission reduction policies since 1980 we calculated the ambient concentrations of air pollutants in the Netherlands from 1980 to 2015, using two scenarios. A Baseline scenario with reported emissions in Europe and a World Avoided scenario which assumed that no air quality policies were adopted from 1980 onwards which would result in the growth in emissions of air pollutants. In the World Avoided scenario, the annual average PM2.5 concentration in the Netherlands increases from 59 μg m−3 in 1980 to 102 μg m−3 in 2015, while in reality (Baseline scenario) concentrations decreased to about 12 μg m−3. The avoided PM2.5 concentration in 2015 accounts for more than half (56%) of reductions in emissions in sectors outside the Netherlands. Foreign (38%) and domestic (16%) industry is the main contributing sector, followed by agriculture (23%) and transport (15%). In 2015, the avoided concentrations of air pollutants correspond to about 700,000 avoided years of life lost in the Netherlands per year, with an associated number of avoided attributable deaths of about 66,000 per year, and an increase in average life expectancy of about 6 years. The corresponding avoided monetary health damage amounts to between € 35 and € 77 billion per year in 2015. Graphical abstract

The oxidation mechanism of 3,4-dihydroxy-2-butanone in the aqueous phase for secondary organic aerosols formation Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Luyao Xu, Guochun Lv, Wen Liu, Xiaomin Sun, Chenxi Zhang, Zhiqiang Li Abstract 3,4-dihydroxy-2-butanone (DHBO) is a major oxidation product of IEPOX and can easily be oxidized in tropospheric aqueous phase. The aqueous oxidation mechanism of DHBO has investigated by DFT and initial reaction rate constants also have calculated through TST. In the aqueous phase, the following trend in reactivity of initial reaction can be obtained: OH ≫ SO4− > NO3, which bases on the calculated rate constants (k(OH) = 1.20 × 108 L mol−1 s−1, k(SO4−) = 8.51 × 105 L mol−1 s−1 and k(NO3) = 2.86 × 105 L mol−1 s−1) at 298 K and 1 atm. After initial reaction, the major products of DHBO further react with OH radical at presence of O2. The final products include acetic acid and methylglyoxal, which are important SOA precursors. This work provides a reference for oxidation mechanism of dihydroxycarbonyl of isoprene-driven in aqueous and help understand SOA formation. Graphical abstract

Observed dependence of surface ozone on increasing temperature in Shanghai, China Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Yixuan Gu, Ke Li, Jianming Xu, Hong Liao, Guangqiang Zhou Abstract Eight-year measurements at urban (Xujiahui, XJH) and remote (Dongtan, DT) sites during time period 2010–2017 are employed to examine the surface ozone (O3)-temperature relationship in Shanghai, China. O3 pollution was getting worse in Shanghai, with daily maximum O3 concentrations increasing at a rate of 2.47 ppb yr−1 in urban site. The climate penalty (mO3-T), defined as the slope of O3 change with increasing temperature, exhibited largest values in summer. Summertime O3 increased faster as temperature increased, with mean rates of 6.65 and 13.68 ppb °C−1, respectively in XJH and DT above 30 °C. Sensitivity experiments indicate that the temperature dependence of biogenic volatile organic compounds (VOCs) emissions could be the main chemical driver of the high-temperature O3 response in summer, since the simulated mO3-T are most sensitive to changes of biogenic isoprene emissions. NOx emission reductions strengthened the high-temperature O3 response, with summer mean mO3-T values increasing from 1.52 ppb°C−1 during 2010–2012 to 2.97 ppb °C−1 during 2013–2017. As NOx emissions continue to decrease, the O3 production in urban Shanghai tend to become transitional and the dependence of mO3-T on the biogenic VOC emissions might be weakened. Model results suggest that anthropogenic VOC emission reductions would effectively relieve O3 pollution and reduce the sensitivity of O3 to increasing temperatures in urban Shanghai. Tailored emission reductions as well as scientific city planning strategies should be formulated to balance VOC/NOx ratios, so as to wrestle with the challenges for future O3 pollution under a warming climate.

Ecotoxicity, genotoxicity, and oxidative potential tests of atmospheric PM10 particles Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): S. Romano, M.R. Perrone, S. Becagli, M.C. Pietrogrande, M. Russo, R. Caricato, M.G. Lionetto Abstract The aim of the present work was to investigate the likely toxicological impact of atmospheric PM10 particles by comparing different effect-based methodologies, namely the Vibrio fischeri bioluminescence inhibition bioassay to evaluate ecotoxicity, the SOS Chromotest assay to estimate genotoxicity, and the Dithiothreitol (DTT) and Ascorbic Acid (AA) acellular assays to assess oxidative potential. The chemical composition was characterized for about 30 species, to assess the potential health impact of specific chemical components. Atmospheric particles were collected from spring to summer at a coastal site of the Central Mediterranean, away from large sources of local pollution. The Toxicity Unit (TU) index, used to assess the ecotoxicity, showed that 33% of the samples were toxic. The Induction Factor (IF), generally used to assess particle's genotoxicity, varied from 0.3 to 1.5 that represents the threshold value for genotoxicity. The oxidative potential (OP) determined by the DTT and AA assay varied within the 4.9–34.5 and 4.8–140.6 nmol min−1 range, respectively. DTT-OP and TU values were significantly correlated with OC, EC, and nss-K+, likely because the DTT and Vibrio fischeri responses were mainly associated with species from combustion sources. The IF factor was significantly correlated with some metals (Al, Ba, La, P, Sr, and Ti) likely from traffic sources and did not show any significant correlation with TU and OP values. Overall, paper's results proved the episodic occurrence of ecotoxicity and genotoxicity levels in PM10 particles sampled directly from their natural environment and away from strong pollution sources, highlighting the role mainly of carbonaceous compounds and heavy metals. The impact of spurious correlations between DTT- and AA-OPV and chemical species concentration has also been addressed. Graphical abstract

Burden of ischemic heart disease and stroke attributable to exposure to atmospheric PM2.5 in Hubei province, China Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Wenyuan Yu, Suyang Liu, Junfeng Jiang, Gongbo Chen, Huijuan Luo, Yuanshan Fu, Lingling Xie, Baojing Li, Na Li, Shu Chen, Hao Xiang, Shenglan Tang Abstract Studies on mortality and disability-adjusted life years (DALYs) of cardiovascular diseases (CVDs) attributable to exposure to ambient PM2.5 in China are very limited. This study aims to provide a city-level estimation of the PM2.5-related disease burden of two major CVDs, ischemic heart disease (IHD) and stroke, by age and sex in Hubei province, China in 2016. PM2.5 mass concentrations (μg/m3) at different cities were obtained from the Hubei Provincial Environmental Quality Supervision and Administration Bureau. The city-level demographic data in Hubei were obtained from the sixth demographic census of China in 2010. Sex- and age-specific mortality and DALY data were extracted from the Global Burden of Disease Study (GBD) 2016. The integrated exposure-response (IER) model, developed by the GBD, was used to estimate PM2.5-related CVD premature deaths and DALYs in Hubei province. We found that 55.76 thousand deaths and 1.11 million DALYs of IHD and stroke could be attributed to exposure to ambient PM2.5 in Hubei. Disease burden of IHD and stroke attributable to PM2.5 increased with age and were higher in males than in females. The PM2.5-related disease burden of IHD and stroke was mainly concentrated in the eastern part of Hubei. The highest population attributable fraction (PAF) of IHD and stroke was mainly concentrated in the western part of Hubei. Our findings suggest that China needs proper air quality management measures to effectively reduce ambient PM2.5, especially for cities with heavy disease burden.

Source apportionment of airborne particulate matters over the Athabasca oil sands region: Inter-comparison between PMF modeling and ground-based remote sensing Publication date: 15 January 2020 Source: Atmospheric Environment, Volume 221 Author(s): Zhenyu Xing, Ying Xiong, Ke Du Abstract The airborne particulate matters (PM) emissions associated with oil sands mining and processing operations in Athabasca oil sands regions (AOSR) could impact ambient air quality. But to what scales the effects could geographically reach remains unclear. The study was conducted to investigate the geographical influence of PM emissions within the AOSR at three sampling sites. The first site is sandwiched by oil sands mining and processing facilities. The second site is an urban site and close to the oil sands mining and processing areas. The third site is a remote rural site. Over the 2-year period (2015 and 2016), the observed geometric mean PM2.5 concentrations at Fort McKay (in AOSR), Fort McMurray (near AOSR), and Anzac (far away from AOSR) were 4.81, 5.89, and 3.30 μg/m3, respectively. The temporal variations of PM2.5 showed more elevated concentrations in spring and summer than winter and fall, which was consistent with the aerosol optical depth (AOD) observation. The Positive Matrix Factorization (PMF) modeling results at the above three sites suggest that anthropogenic sources were the dominant contributors of ambient aerosol concentrations within AOSR. According to the depleted vanadium (V) content in the surface dust factor from near AOSR site to remote site, the influence of petroleum coke dust as the primary source on aerosol emissions is geographically limited. The result also revealed the considerably long lasting influence of bitumen spill on the local aerosol source contributions. From the ground-based remote sensing observations of aerosol optical properties, petroleum coke could influence the atmospheric aerosol levels over AOSR with highly light-absorbing coarse-mode aerosols under warm and dry weather conditions.