Northeast China has been reported as having serious air pollution in China with increasing occurrences of severe haze episodes. Changchun City, as the center of Northeast China, has longstanding industry and is an important agricultural base. Additionally, Changchun City has a long winter requiring heating of buildings emitting pollution into the air. These factors contribute to the complexity of haze pollution in this area. In order to analyze the causes of heavy haze, surface air quality has been monitored from 2013 to 2015. By using satellite and meteorological data, atmospheric pollution status, spatio-temporal variations and formation have been analyzed. Results indicated that the air quality in 88.9% of days exceeding air quality index (AQI) level-1 standard (AQI >50) according to the National Ambient Air Quality Standard (NAAQS) of China. Conversely, 33.7% of the days showed a higher level with AQI > 100. Extreme haze events (AQI > 300) occurred frequently during agricultural harvesting period (from October 10 to November 10), intensive winter heating period (from Late-December to February) and period of spring windblown dust (April and May). Most daily concentrations of gaseous pollutants, i.e., NO 2 (43.8 μg/m 3), CO (0.9 mg/m 3), SO 2 (37.9 μg/m 3), and O 3 (74.9 μg/m 3) were evaluated within level-1 concentration limits of NAAQS standards. However, particulate matter (PM 2.5 and PM 10) concentrations (67.3 μg/m 3 and 115.2 μg/m 3 , respectively) were significantly higher than their level-1 limits. Severe haze in spring was caused by offsite transported dust and windblown surface soil. Heavy haze periods during fall and winter were mainly formed by intensive emissions of atmospheric pollutants and steady weather conditions (i.e., low wind speed and inversion layer). The overlay emissions of widespread straw burning and coal combustion for heating were the dominant factors contributing to haze in autumn, while intensive coal burning during the coldest time was the primary component of total emissions. In addition, general emissions including automobile exhaust, road and construction dust, residential and industrial activities, have significantly increased in recent years, making heavy haze a more frequent occurrence. Therefore, both improved technological strategies and optimized pollution management on a regional scale are necessary to minimize emissions in specified seasons in Changchun City, as well as comprehensive control measures in Northeast China.
Investigations using electrical impedance spectroscopy to measure the responses of fish embryos to the cryoprotective chemicals, methanol and dimethyl sulphoxide (DMSO), were carried out. Zebrafish (Danio rerio) embryos were used as a model to study the newly proposed technique. The normalised permittivity and conductivity changes of the embryos were measured continuously over a 20-min period in a customised embryo-holding chamber. The normalised permittivity and conductivity spectra were obtained during embryo exposure to different concentrations of methanol (1.0, 2.0 and 3.0 M) and DMSO (0.5, 1.0 and 2.0 M) solutions. The results showed significant permittivity and conductivity changes after embryo exposure to methanol and DMSO at the optimum embryo loading level (six embryos). Embryos in different concentrations of methanol and DMSO also resulted in quantitative responses shown in the normalised permittivity and conductivity spectra. The results demonstrated that fish embryo membrane permeability to cryoprotective chemicals could be monitored in real-time. The measurement of permittivity at a lower frequency range (10-10(3) Hz) and conductivity at a higher frequency range (10(4)-10(6) Hz) during fish embryo exposure to cryoprotective chemicals using impedance spectroscopy can be used as a new tool for the fast screening of most effective cryoprotective chemicals. The results from the present study also demonstrated the possibility of quantifying the level of cryoprotective chemicals penetrating the fish embryos.
Carbonaceous aerosol, one of the major components of atmospheric aerosols, significantly affects haze episodes, climate change, and human health. Northeastern China suffers severe air pollution, especially in some periods (e.g., the Spring Festival). However, studies on carbonaceous aerosols in typical northeast industrial cities (i.e., Changchun) are rare, limiting further comprehension of the atmospheric haze formation. In this study, we monitored the concentrations of carbonaceous aerosols (i.e., OC and EC) in Changchun during the Lunar New Year of 2018 (i.e., from Lunar 20 December to Lunar 20 January), and analyzed the temporal variation and source contributions via the HYbrid-Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model with the potential source contribution factor weights (PSCF) method. The daily concentrations of OC and EC were 9.00 ± 2.81 and 1.57 ± 0.46 µg m−3, respectively, and were significantly lower at nighttime than at the day during the Spring Festival. The concentrations during the major period (i.e., OC: 8.13 ± 2.93 µg m−3; EC: 1.47 ± 0.47 µg m−3 in festival days), including the Lunar Little New Year; the Lunar New Year’s Eve; New Year’s Day; Lunar 5 January, and the Spring Lantern Festival, were mainly from the northwestward with the wind speed of 4–6 m/s being lower than that of normal period (OC: 9.87 ± 2.46 µg m−3; EC: 1.67 ± 0.44 µg m−3) from the southeastward with a wind speed of 6–7 m/s. The direction of the airflow trajectory was mainly in local, northwestward, and northward, carrying particulate matter and gaseous pollutants. In major period, the daily concentration of atmospheric pollutants presented a bimodal trend, with peaks appearing regularly from 11:00 a.m. to 12:00 p.m. and 5:00 p.m. 10:00 p.m., which might be related to traffic, cooking, and firecrackers. The OC/EC was greater than 2 during the whole period, indicating the generation of secondary organic aerosols (i.e., SOC). This study was essential to understand the formation mechanisms of severe pollution episodes and develop control measures for the industrial cities of Northeast China during the Spring Festival.
Generally, the period (i.e., October and November) was seriously affected by frequent atmospheric pollution under concentrative seasonal crop residue burning and coal burning in Jilin Province, Northeast China. A strict straw open burning ban policy was implemented in Jilin Province during October and November 2018. However, the quantitative effect of straw fire control and its effect on air quality are still unclear. In this study, using multisource data, we evaluated the status of straw-burning control and its contribution to air quality improvement in late autumn and early winter (i.e., October and November) of 2018 at a provincial level. The results showed that the open burning of straw was effectively controlled in October and November 2018 by comparing farmland fire point data to those collected in 2015–2017. There were significant positive correlations among the fire points, aerosol optical depth (AOD), and ground-monitored air quality index (AQI) on a spatial scale. The concentration values of AQI, PM2.5, and PM10 were significantly lower than for the other three years of 2015, 2016, and 2017. Based on meteorological analysis, similar conditions were found in 2018 and 2017, which were worse than that in 2016. Combined with emissions, meteorological conditions, and source apportionment information, if the straw-burning control of 2018 had been performed in 2016 and 2017, the PM2.5 concentrations could have been reduced by at least 30.6%. These results suggest the necessity of straw burning control in the improvement of air quality during the period of late autumn and early winter. Nevertheless, the comprehensive impact of straw-burning control on air quality should be further evaluated for the whole post-harvest period (i.e., October to April of the following year) as the straw-burning period can be postponed in some cities. Furthermore, the establishment of a scientific and reasonable planned burning of straw is also crucial in gradually reducing atmospheric pollution and the actual operation of local governments in those areas where straw can be burned under certain conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.