Atmospheric Environment

Extreme levels and chemistry of PM from the consumer fireworks in the Netherlands Publication date: 1 September 2019 Source: Atmospheric Environment, Volume 212 Author(s): Harry ten Brink, René Otjes, Ernie Weijers Abstract Mass concentrations of Particulate Matter (PM) in New-Year's nights can be high in the Netherlands because of the unconstrained use of consumer fireworks. In the study presented here the chemical compounds of the PM were determined. It is for the first time that this information was used to deduced the average composition of the explosive mixture/black powder. Measurements were made during the turn of the year 2007–2008 at an urban background location, when hourly PM10 mass concentrations exceeded 2000 μg m−3 at street sites. These extreme levels were due to the stagnant weather conditions occurring that night. The on-line artefact-free “MARGA” was deployed for assessment of the major compounds. These were found to be the (hygroscopic) salts KCl, MgSO4 and K2SO4. The mass ratio of sulphur and potassium showed that a standard black powder mix is used as explosive. The potassium was for 65% present as KCl. This is the reduction product of the oxidiser KClO4, which is hence the main oxidiser. The rest of the potassium was present in the form of K2SO4. We proved that this compound derives from the “standard” oxidiser KNO3 of black powder. The formation of the SO42--salts is explained as follows. The sulphur in the black powder oxidises to H2SO4. This compound reacts with the reduction product of the KNO3 to K2SO4. MgSO4 forms in a reaction of the main colouring agent magnesium with the H2SO4. The full composition of the PM, including carbonaceous material and trace metals, was obtained from an analysis of 24-hr filter samples. This showed that the mentioned salts comprised about half of the mass, while almost all of the remainder is “carbon” deriving from the incomplete combustion of the cardboard wrapping. About 85% of the PM10 is in the more harmful PM2.5.

Multiple perspectives for modeling regional PM2.5 transport across cities in the Beijing–Tianjin–Hebei region during haze episodes Publication date: 1 September 2019 Source: Atmospheric Environment, Volume 212 Author(s): Hanyu Zhang, Shuiyuan Cheng, Sen Yao, Xiaoqi Wang, Junfeng Zhang Abstract Regional transport always plays a crucial role in the formation and dissipation of haze over the Beijing–Tianjin–Hebei (BTH) region. This study, conducted using pollution and meteorological observations and the Weather Research and Forecasting model (WRF) coupled with the Comprehensive Air Quality Model with Extensions (CAMx), investigated the possible meteorological causes for the occurrence of haze pollution and quantitatively assessed the PM2.5 transport contribution to haze episodes that occurred in Beijing in January and July 2015. The results indicated that modeling system reproduced the spatial-temporal variation in PM2.5 concentrations in the BTH region well. During the study period, haze episodes were primarily attributed to meteorological conditions such as planetary boundary layer height, relative humidity, wind vector, and temperature inversion, in the context of pollution emissions. Analysis of surface PM2.5 transport showed that 62.89% of the surface PM2.5 in Beijing was came from local emissions, with the remaining 23.69% and 13.42%, on average, originating from short- and long-range transport during the study period. The percentage of contribution varied with the evolutionary stage of the haze episodes, showing the joint influence of local emissions and regional transport on haze pollution in Beijing. Additionally, investigation of vertical PM2.5 transport identified the following three major pathways: a northwest–southeast pathway in January (at all layers below 1200 m, though it was stronger above 600 m), a southeast–northwest pathway in July (at all layers below 800 m), and a southwest–northeast pathway during both months (at a height of 200–1200 m). Moreover, the magnitude of daily PM2.5 transport fluxes during the haze episodes was generally stronger than the corresponding monthly average. These results provide a scientific basis for strategic control of both multiple cities and provinces and in-depth knowledge of the mechanisms and sources of haze pollution in the BTH region. Graphical abstract

Comparative statistical models for estimating potential roles of relative humidity and temperature on the concentrations of secondary inorganic aerosol: Statistical insights on air pollution episodes at Beijing during January 2013 Publication date: 1 September 2019 Source: Atmospheric Environment, Volume 212 Author(s): Bin Han, Yunlong Wang, Rui Zhang, Wen Yang, Zhiqiang Ma, Wei Geng, Zhipeng Bai Abstract Heavy air pollution attacked Beijing and its surrounding areas in January of 2013, which attracted large attentions from around the world. In this study, we conducted highly time-resolved measurements of inorganic ions associated with PM2.5 at an urban site in Beijing during this period. We applied the curve fitting method, the quantile regression model and the probability function model to evaluate the relationship between secondary inorganic ions (sulfate, nitrate and ammonium, SNA) and meteorological parameters (relative humidity (RH) and temperature). In our model results, RH was regarded as one of the key factors of high concentrations of SNA, and high level of RH would enhance the concentrations of SNA. In addition, the effect of temperature was also important and noticeable. We further constructed a probability function model to investigate the joint effects of RH and temperature. The model results showed higher RH and a temperature of approximately −5 °C (−4∼-6 °C for sulfate and nitrate; −5∼-7 °C for ammonium) would be the most suitable conditions for the high concentrations of SNA during the air pollution episodes in Beijing. Graphical abstract

Evaluation of semi-static enclosure technique for rapid surveys of biogenic volatile organic compounds (BVOCs) emission measurements Publication date: 1 September 2019 Source: Atmospheric Environment, Volume 212 Author(s): Lingyu Li, Alex B. Guenther, Shaodong Xie, Dasa Gu, Roger Seco, Sanjeevi Nagalingam, Dongyun Yan Abstract Biogenic volatile organic compounds (BVOCs) are important drivers of atmospheric chemical composition and accurate model simulations require characterization of the emissions associated with specific vegetation types which is typically determined using enclosure measurements. Static enclosure techniques were used for past BVOC emission measurement studies, especially in the 1960s–1980s, but are no longer widely used because of concerns that the resulting emission rates are not representative. The main advantages of the static approach are the capability for rapid measurements and a lower detection limit that enables the use of less sensitive analytical techniques. We evaluate a version of the static approach which we call the semi-static approach. In order to evaluate the performance of the semi-static approach for BVOCs emission measurements, multiple replicate measurements for different plants were conducted in a laboratory growth chamber using both semi-static and dynamic enclosure techniques. Variability of replicate measurements was calculated and the results from the two techniques were compared. The semi-static technique provided consistent measurements for isoprene but not for α-pinene, β-pinene and other compounds that are stored in leaves. The measured isoprene emission factors were much higher than dynamic measurements. There were a large number of compounds to be detected by dynamic technique that could not be detected by the semi-static technique. But the semi-static technique could still provide qualitative information on categorization of non, low and high emitters for some compounds.

Ozone dose-response relationships for soil microbial dynamics of winter wheat in North China Publication date: 1 September 2019 Source: Atmospheric Environment, Volume 212 Author(s): Enzhu Hu, Ruinan Dong, Xiangli Nan, Zaijian Yuan, Hongxing Zhang, Xiaoke Wang, Weiwei Zhang Abstract Dynamic responses of soil microbial properties of winter wheat (Triticum aestivum L.) to elevated ozone concentration have never been quantified. In this study, the winter wheat was cultivated under two contrasting ozone treatments: non-filtered ambient air (hereinafter called NF) and elevated ozone (effective increase in 9-h mean ozone concentration of 34.91 ± 1.42 nL·L−1 (mean ± SE) above ambient, hereinafter called EO3). Linear regressions between the response ratio of each variable (i.e. EO3/NF) and the increments of exposure- or flux-based ozone indices (i.e. EO3 - NF) were conducted. The results showed that the response ratios of soil microbial biomass C and N, as well as cumulative CO2 and N2O effluxes significantly correlated with the increments of ozone indices. The ΔPOD0 (increment of integrated phytotoxic ozone dose with no threshold) and the ΔAOT40 (increment of accumulated hourly O3 concentrations over a threshold of 40 nL·L−1) performed better than ΔSUM06, ΔW126 and the increments of other flux-based ozone indices. They showed stronger linear relationships with soil microbial biomass than that with gas effluxes. The expanded deviations from the effect-free line indicated distinct cumulative detrimental ozone impacts on soil microbial properties. Ammonia nitrogen content and nitrite reductase activity showed non-significantly adaptive and self-adjustment responses to accumulative ozone stress. The ozone dose-response relationships obtained here will benefit the ecological modeling that evaluates the dynamic responses or predicts the feedback effects of sustainable agro-ecosystems under global climate change.

Application of a sensor network of low cost optical particle counters for assessing the impact of quarry emissions on its vicinity Publication date: 15 August 2019 Source: Atmospheric Environment, Volume 211 Author(s): Yuval, Hadas Magen Molho, Ohad Zivan, David M. Broday, Raanan Raz Abstract The adverse health effects of inhaled particulate matter (PM) are global concern. Yet, in general, estimating the exposure to PM is challenging due to the sparsity of standard air quality monitoring stations and the low accuracy of dispersion models when high spatial resolution is required. The city of Elad, Israel, is situated less than 1 km from the Migdal Tzedek stone quarry, and public concerns were raised regarding the impact of the quarry's PM emissions on the city air quality. This work describes a year-long campaign of continuous measurements of particle number concentration (PNC) in few locations in the city and its vicinity, using a network of low cost optical particle counters (OPCs). To assess the possible impact of the quarry on the city we examined the OPCs' accuracy, coherency, and their capability to detect the quarry's impact on the PNC levels in the city. Using PNC time series in two size channels from a network of five nodes, PM10 and PM2.5 records from a nearby reference air quality monitoring station, and meteorological data, we could conclude that the quarry's impact on the city was small relative to the background PNC levels. Yet, more importantly, this work demonstrates the use of a network of low cost OPCs for responding to an environmental query for which the sparse standard air quality monitoring observations were not sufficient. The trade-offs between deployment of a network of cheap low-quality instruments and the use of a single high-end device are discussed. Graphical abstract

Significant secondary organic aerosol production from aqueous-phase processing of two intermediate volatility organic compounds Publication date: 15 August 2019 Source: Atmospheric Environment, Volume 211 Author(s): Junchen Lu, Xinlei Ge, Yu Liu, Yanfang Chen, Xinchun Xie, Yang Ou, Zhaolian Ye, Mindong Chen Abstract Intermediate volatility organic compounds (IVOCs) recently have been identified as an important group of air pollutants, and they can contribute significantly to the secondary organic aerosol (SOA) formation via gas-phase reactions. However, significance of the SOA from aqueous oxidation of IVOCs was largely unknown. Here, we investigated the aqueous aging of two model IVOCs of naphthoquinone (NAQ) and phenanthrene (PHE) at a staring concentration of 10 μM. Both species were found to have high SOA yields (∼50%) against hydroxyl radical photochemical oxidation. PHE can be slowly oxidized under dark conditions (∼10% in 8 h) while NAQ cannot, but it can photo-degrade itself under simulated sunlight at a high rate (∼56% in 1 h). A group of oxygenated products were formed and its concentrations increased continuously throughout hydroxyl radical-mediated aging of both precursors. Aqueous aging led to enhancements of light absorption, especially for NAQ, and the oxygenated products were likely light chromophores. Our findings highlight the possible significance of SOA from aqueous oxidation of IVOCs. Future investigations on a broad spectrum of IVOCs and inclusion of such SOA formation pathway into climate and air quality models should be considered. Graphical abstract

Characterization of trace aerosol compositions produced during the OH radical-initiated photooxidation of β-pinene Publication date: 15 August 2019 Source: Atmospheric Environment, Volume 211 Author(s): Peng Zhang, Jingyun Huang, Jinian Shu, Pengkun Ma, Bo Yang Abstract The detailed molecular composition of laboratory-generated secondary organic aerosols (SOA) during the high-NO photooxidation of β-pinene (βP) was investigated using a novel thermal desorption dichloromethane-assisted low-pressure photoionization mass spectrometry (TD-CH2Cl2-assisted LPPI-MS) technique. We found that protonated norpinone gave the highest signal intensity, which supported that assumption that this compound was the key oxidation species responsible for promoting βP-SOA formation. In addition to the previously identified monomers (i.e., 2,2-dimethylcyclobutyl-1,3-dicarboxaldehyde (m/z 140), pinene aldehyde (m/z150), myrtenol (m/z 152), (2,2-dimethyl-3-acetyl)-cyclobutylformate (m/z 156), pinene acid (m/z 166), and isomers of pinalic-3-acid (m/z 170)), two additional nitrogen-containing species (i.e., C10 hydroxy nitrate and C10carbonyl nitrate) were also observed at m/z values of 214 and 216 in the mass spectrum of βP-SOA. Furthermore, the losses of 18 (H2O), 46 (NO2), and 64 (H2O + NO2) were attributed to the typical fragmentation pathways of the two nitrogen-containing species. Overall, these results not only contribute to an improved understanding of βP-SOA formation, but they also indicate that TD-CH2Cl2-assisted LPPI-MS can be used as a novel detection means to study SOA formation.

Characteristics of isoprene emission from moso bamboo leaves in a forest in central Taiwan Publication date: 15 August 2019 Source: Atmospheric Environment, Volume 211 Author(s): Tingwei Chang, Tomonori Kume, Motonori Okumura, Yoshiko Kosugi Abstract The expansion of moso bamboo (Phyllostachys edulis) may potentially impact regional isoprene emissions. Modeling based on field measurements is an effective approach for assessing the potential impact of the moso bamboo expansion. The G93 algorithm is one of the most widely used models, however no studies have tested the applicability of the algorithm for moso bamboo isoprene emission. This study was undertaken to establish a model for reproducing moso bamboo isoprene emission fluxes. To this aim, this study examined 1) the isoprene emission ability of moso bamboo, and 2) its responses to environmental factors such as leaf temperature and light. We also tested 3) the reproducibility of the G93 algorithm for moso bamboo isoprene emission fluxes. This study used a chamber method with a modified photosynthesis system and carbon absorbents to quantify isoprene emitted from bamboo leaves in central Taiwan under the humid subtropical climate. First, we screened isoprene emission from 12 bamboo species, and the results confirmed that moso bamboo exhibited significant isoprene emission potential. Second, we measured isoprene emission fluxes from moso bamboo leaves with light controls every month from summer to spring. The isoprene emission fluxes increased with photosynthetic photon flux density (PPFD); under sufficient PPFD conditions, the seasonal changes in the isoprene emission fluxes were regulated by leaf temperature, and low isoprene emission fluxes were found in low leaf temperature conditions. Thirdly, overestimations were observed in the G93 algorithm with the original parameters in periods with leaf temperatures <23 °C. Using the G93 algorithm with site-specific parameters could improve the overestimation in the low-temperature period. This study suggests the necessity of parameterization in the G93 algorithm to reproduce the suppression of isoprene emission fluxes from moso bamboo leaves in the low-temperature period.

Estimation of biomass-burning emissions by fusing the fire radiative power retrievals from polar-orbiting and geostationary satellites across the conterminous United States Publication date: 15 August 2019 Source: Atmospheric Environment, Volume 211 Author(s): Fangjun Li, Xiaoyang Zhang, David P. Roy, Shobha Kondragunta Abstract Biomass burning is an important source of atmospheric greenhouse gases and aerosols, and its emissions can be estimated using Fire Radiative Power (FRP) retrievals from polar-orbiting and geostationary satellites. Accurate and timely estimation of biomass-burning emissions (BBE) requires high-spatiotemporal-resolution FRP that is characterized by accurate diurnal FRP cycle. This study is to estimate hourly reliable BBE in a 0.25° × 0.3125° grid across the conterminous United States (CONUS) to be used in chemical transport models for air quality forecast. To do this, this study for the first time fused FRP retrievals from the Geostationary Operational Environmental Satellite (GOES) with those from Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 after GOES FRP was angularly adjusted and was further calibrated against MODIS FRP. The FRP data was obtained from Terra and Aqua MODIS 1 km active fire products with fire observations of four times a day and from 4 km GOES WF_ABBA (WildFire Automated Biomass Burning Algorithm) fire products for GOES-W (GOES-11 and 15) and GOES-E (GOES-13) with observations every 5–15 min across the CONUS from 2011 to 2015. The diurnal FRP cycles at an interval of 15 min for a grid were reconstructed using the ecosystem-specific diurnal FRP climatology and actually available MODIS-GOES fused FRP, which were applied to estimate hourly BBE across the CONUS. The results indicate that the reconstructed diurnal FRP cycle varied significantly in magnitude and shape among 45 CONUS ecosystems. The biomass burning released 717 Gg particulate matter smaller than 2.5 μm in diameter (PM2.5) in the CONUS each year; however, it presented significant temporal (diurnal, seasonal, and interannual) and spatial variations. Finally, the BBE estimates were evaluated using available data sources and compared well (a difference of ∼4%) with emissions derived from Landsat burned areas in the western CONUS and with hourly carbon monoxide emissions simulated using a biogeochemical model over the Rim Fire in California (difference < 1%). The BBE estimates showed similar seasonal variation to six available BBE inventories but with variable magnitude.