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Nitrogen dioxide (NO₂) and formaldehyde (HCHO) play vital roles in atmospheric photochemical processes. Their tropospheric vertical column density (TVCD) distributions have been monitored by satellite instruments. Evaluation of these observations is essential for applying these observations to study photochemistry. Assessing satellite products using observations at rural sites, where local emissions are minimal, is particularly useful due in part to the spatial homogeneity of trace gases. In this study, we evaluate OMI and TROPOMI NO₂and HCHO TVCDs using multi‐axis differential optical absorption spectroscopy (MAX‐DOAS) measurements at a rural site in the east coast of the Shandong province, China in spring 2018 during the Ozone Photochemistry and Export from China Experiment (OPECE) measurement campaign. On days not affected by local burning, we found generally good agreement of NO₂data after using consistent a priori profiles in satellite and MAX‐DOAS retrievals and accounting for low biases in scattering weights in one of the OMI products. In comparison, satellite HCHO products exhibited weaker correlations with MAX‐DOAS data, in contrast to satellite NO₂products. However, TROPOMI HCHO products showed significantly better agreement with MAX‐DOAS measurements compared to OMI data. Furthermore, case studies of the vertical profiles measured by MAX‐DOAS on burning days revealed large enhancements of nitrous acid (HONO), NO₂, and HCHO in the upper boundary layer, accompanied with considerable variability, particularly in HONO enhancements.

 

The continued development of the automotive industry has led to a rapid increase in the amount of waste rubber tires, the problem of “black pollution” has become more serious but is often ignored. In this study, the emission characteristics, health risks, and environmental effects of volatile organic compounds (VOCs) from a typical, recycled rubber plant were studied. A total of 15 samples were collected by summa canisters, and 100 VOC species were detected by the GC/MS-FID system. In this study, the total VOCs (TVOCs) concentration ranged from 1000 ± 99 to 19,700 ± 19,000 µg/m3, aromatics and alkanes were the predominant components, and m/p-xylene (14.63 ± 4.07%–48.87 ± 3.20%) could be possibly regarded as a VOCs emission marker. We also found that specific similarities and differences in VOCs emission characteristics in each process were affected by raw materials, production conditions, and process equipment. The assessment of health risks showed that devulcanizing and cooling had both non-carcinogenic and carcinogenic risks, yarding had carcinogenic risks, and open training and refining had potential carcinogenic risks. Moreover, m/p-xylene and benzene were the main non-carcinogenic species, while benzene, ethylbenzene, and carbon tetrachloride were the dominant risk compounds. In the evaluation results of LOH, m/p-xylene (25.26–67.87%) was identified as the most key individual species and should be prioritized for control. In conclusion, the research results will provide the necessary reference to standardize the measurement method of the VOCs source component spectrum and build a localized source component spectrum. 

Ambient carbonyls are critical precursors of ozone (O3) and secondary organic aerosols (SOA). To better understand the pollution characteristics of carbonyls in Taiyuan, field samplings were conducted, and 13 carbonyls were detected in an urban site of Taiyuan for the four seasons. The total concentration of carbonyls in the atmosphere was 19.67 ± 8.56 μg/m3. Formaldehyde (7.70 ± 4.78 μg/m3), acetaldehyde (2.95 ± 1.20 μg/m3) and acetone (5.57 ± 2.41 μg/m3) were the dominant carbonyl compounds, accounting for more than 85% of the total carbonyls. The highest values for formaldehyde and acetone occurred in summer and autumn, respectively, and the lowest occurred in winter. The variations for acetaldehyde were not distinct in the four seasons. Formaldehyde and acetone levels increased obviously in the daytime and decreased at night, while acetaldehyde did not show significant diurnal variations. Higher temperature and stronger sunlight intensity could facilitate the photochemical reaction of volatile organic compounds (VOCs) and enhance the O3 levels in summer. Formaldehyde and acetaldehyde contributed 70–95% of carbonyls’ ozone formation potential (OFP) caused by carbonyls with the highest totals of 268.62 μg/m3 and 38.14 μg/m3, respectively. The highest concentrations of carbonyls from south and southwest winds in summer suggest that the coke industries in the southern Taiyuan Basin should be, firstly, controlled for the alleviation of ozone pollution. 

Abstract. A new ion source (IS) utilizing vacuum ultraviolet (VUV) light is developed and characterized for use with iodide–chemical ionization massspectrometers (I−-CIMS). The VUV-IS utilizes a compact krypton lamp that emits light at two wavelengths corresponding to energies of∼10.030 and 10.641 eV. The VUV light photoionizes either methyl iodide (ionization potential, IP = 9.54 ± 0.02 eV)or benzene (IP = 9.24378 ± 0.00007 eV) to form cations and photoelectrons. The electrons react with methyl iodide to formI−, which serves as the reagent ion for the CIMS. The VUV-IS is characterized by measuring the sensitivity of a quadrupole CIMS (Q-CIMS) toformic acid, molecular chlorine, and nitryl chloride under a variety of flow and pressure conditions. The sensitivity of the Q-CIMS, with theVUV-IS, reached up to ∼700 Hz pptv−1, with detection limits of less than 1 pptv for a 1 min integration period. Thereliability of the Q-CIMS with a VUV-IS is demonstrated with data from a month-long ground-based field campaign. The VUV-IS is further tested byoperation on a high-resolution time-of-flight CIMS (TOF-CIMS). Sensitivities greater than 25 Hz pptv−1 were obtained for formic acid andmolecular chlorine, which were similar to that obtained with a radioactive source. In addition, the mass spectra from sampling ambient air wascleaner with the VUV-IS on the TOF-CIMS compared to measurements using a radioactive source. These results demonstrate that the VUV lamp is a viablesubstitute for radioactive ion sources on I−-CIMS systems for most applications. In addition, initial tests demonstrate that the VUV-IS canbe extended to other reagent ions by the use of VUV absorbers with low IPs to serve as a source of photoelectrons for high IP electron attachers,such as SF6-. 

Ischemic heart injury causes permanent cardiomyocyte loss and fibrosis impairing cardiac function. Tissue derived biomaterials have shown promise as an injectable treatment for the post‐ischemic heart. Specifically, decellularized extracellular matrix (dECM) is a protein rich suspension that forms a therapeutic hydrogel once injected and improves the heart post‐injury response in rodents and pig models. Current dECM‐derived biomaterials are delivered to the heart as a liquid dECM hydrogel precursor or colloidal suspension, which gels over several minutes. To increase the functionality of the dECM therapy, an injectable solid dECM microparticle formulation derived from heart tissue to control sizing and extend stability in aqueous conditions is developed. When delivered into the infarcted mouse heart, these dECM microparticles protect cardiac function promote vessel density and reduce left ventricular remodeling by sustained delivery of biomolecules. Longer retention, higher stiffness, and slower protein release of dECM microparticles are noted compared to liquid dECM hydrogel precursor. In addition, the dECM microparticle can be developed as a platform for macromolecule delivery. Together, the results suggest that dECM microparticles can be developed as a modular therapy for heart injury.

 

Abstract. Mixing ratios of volatile organic compounds (VOCs) were recordedin two field campaigns in central Beijing as part of the Air Pollution andHuman Health in a Chinese Megacity (APHH) project. These data were used tocalculate, for the first time in Beijing, the surface–atmosphere fluxes ofVOCs using eddy covariance, giving a top-down estimation of VOC emissionsfrom a central area of the city. The results were then used to evaluate theaccuracy of the Multi-resolution Emission Inventory for China (MEIC). TheAPHH winter and summer campaigns took place in November and December 2016and May and June 2017, respectively. The largest VOC fluxes observed were ofsmall oxygenated compounds such as methanol, ethanol + formic acid andacetaldehyde, with average emission rates of 8.31 ± 8.5, 3.97 ± 3.9 and 1.83 ± 2.0 nmol m−2 s−1, respectively, in the summer.A large flux of isoprene was observed in the summer, with an average emissionrate of 5.31 ± 7.7 nmol m−2 s−1. While oxygenated VOCs madeup 60 % of the molar VOC flux measured, when fluxes were scaled by ozoneformation potential and peroxyacyl nitrate (PAN) formation potential thehigh reactivity of isoprene and monoterpenes meant that these speciesrepresented 30 % and 28 % of the flux contribution to ozone and PANformation potential, respectively. Comparison of measured fluxes with theemission inventory showed that the inventory failed to capture the magnitudeof VOC emissions at the local scale.