共查询到20条相似文献，搜索用时 26 毫秒
1.
Nicholas J. Gingerysty Charles A. Odame-Ankrah Nick Jordan Hans D. Osthoff 《环境科学学报(英文版)》2021,33(9):184-193
The reference method to quantify mixing ratios of the criteria air pollutant nitrogen dioxide (NO2) is NO-O3 chemiluminescence (CL), in which mixing ratios of nitric oxide (NO) are measured by sampling ambient air directly, and mixing ratios of NOx (= sum of NO and NO2) are measured by converting NO2 to NO using, for example, heated molybdenum catalyst or, more selectively, photolytic conversion (P-CL). In this work, the nitrous acid (HONO) interference in the measurement of NO2 by P-CL was investigated. Results with two photolytic NO2 converters are presented. The first used radiation centered at 395 nm, a wavelength region commonly utilized in P-CL. The second used light at 415 nm, where the overlap with the HONO absorption spectrum and hence its photolysis rate are less. Mixing ratios of NO2, NOx and HONO entering and exiting the converters were quantified by Thermal Dissociation Cavity Ring-down Spectroscopy (TD-CRDS). Both converters exhibited high NO2 conversion efficiency (CFNO2; > 90%) and partial conversion of HONO. Plots of CF against flow rate were consistent with photolysis frequencies of 4.2 s-1 and 2.9 s-1 for NO2 and 0.25 s-1 and 0.10 s?1 for HONO at 395 nm and 415 nm, respectively. CFHONO was larger than predicted from the overlap of the emission and HONO absorption spectra. The results imply that measurements of NO2 by P-CL marginally but systematically overestimate true NO2 concentrations, and that this interference should be considered in environments with high HONO:NO2 ratios such as the marine boundary layer or in biomass burning plumes. 相似文献
2.
Chengzhi Xing Cheng Liu Qihou Hu Qingyan Fu Shanshan Wang Hua Lin Yizhi Zhu Shuntian Wang Weiwei Wang Zeeshan Jave Xiangguang Ji Jianguo Liu 《环境科学学报(英文版)》2021,33(7):44-55
Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations were operated from 02 to 21 December 2018 in Leshan, southwest China, to measure HONO, NO2 and aerosol extinction vertical distributions, and these were the first MAX-DOAS measurement results in Sichuan Basin. During the measurement period, characteristic ranges for surface concentration were found to be 0.26–4.58 km?1 and averaged at 0.93 km?1 for aerosol extinction, 0.49 to 35.2 ppb and averaged at 4.57 ppb for NO2 and 0.03 to 7.38 ppb and averaged at 1.05 ppb for HONO. Moreover, vertical profiles of aerosol, NO2 and HONO were retrieved from MAX-DOAS measurements using the Heidelberg Profile (HEIPRO) algorithm. By analysing the vertical gradients of pollutants and meteorological information, we found that aerosol and HONO are strongly localised, while NO2 is mainly transmitted from the north direction (city center direction). Nitrogen oxides such as HONO and NO2 are important for the production of hydroxyl radical (OH) and oxidative capacity in the troposphere. In this study, the averaged value of OH production rate from HONO is about 0.63 ppb/hr and maximum value of ratio between OH production from HONO and from (HONO+O3) is > 93% before12:00 in Leshan. In addition, combustion emission contributes to 26% for the source of HONO in Leshan, and we found that more NO2 being converted to HONO under the conditions with high aerosol extinction coefficient and high relative humidity is also a dominant factor for the secondary produce of HONO. 相似文献
3.
Fanhao Meng Min Qin Wu Fang Jun Duan Ke Tang Helu Zhang Dou Shao Zhitang Liao Yan Feng Yong Huang Ting Ni Pinhua Xie Jianguo Liu Wenqing Liu 《环境科学学报(英文版)》2022,34(4):297-307
To investigate nitrous acid(HONO) levels and potential HONO sources above crop rotation fields. The HONO fluxes were measured by the aerodynamic gradient(AG) method from 14 December 2019 to 2 January 2020 over an agricultural field in the Huaihe River Basin. The ambient HONO levels were measured at two different heights(0.15 and 1.5 m), showing a typical diurnal cycle with low daytime levels and high nighttime levels. The upward HONO fluxes were mostly observed during the day, whereas deposition... 相似文献
4.
The heterogeneous uptake processes of hydrogen peroxide on Arizona test dust and two types of authentic Chinese mineral dusts, i.e., Inner Mongolia desert dust and Xinjiang calciferous dust, were investigated using a Knudsen cell reactor coupled with a quadrupole mass spectrometer. The uptake coefficients were measured as a function of the initial concentration of H_2O_2 from 2.6 × 10~(11) to 1.2 × 10~(12)molecules/cm~3, and the temperature dependence of the uptake coefficients was investigated over a range from 253 to 313 K. The concentration of H_2O_2 showed little effect on the uptake coefficients of these heterogeneous processes. As a function of temperature, the initial uptake coefficients decrease with increasing temperature, whereas the steady state uptake coefficients of Arizona test dust and Inner Mongolia desert dust increase with increasing temperature. Implications for the understanding of the uptake processes onto mineral dust samples were also discussed. 相似文献
5.
Zhiyan Li Pinhua Xie Renzhi Hu Dan Wang Huawei Jin Hao Chen Chuan Lin Wenqing Liu 《环境科学学报(英文版)》2020,32(9):248-255
The nitrate radical(NO3) and dinitrogen pentoxide(N2.5) play an important role in the nocturnal atmosphere chemistry.Observations of N03 radicals and N2 O5 were performed in a semirural ground site at Tai’Zhou in polluted southern China using cavity ring down spectroscopy(CRDS) from 23 May to 15 June 2018.The observed N03 and N2 O5 concentrations were relatively low,with 1 min average value of 4.4±2.2 and 26.0±35.7 pptV,respective... 相似文献
6.
Fugitive road dust (FRD) contributes a great deal to urban rainwater and air pollution and is commonly controlled by water-sprinkling in most Chinese cities. However, there is a lack of information on its effectiveness. We used the Testing Re-entrained Aerosol Kinetic Emissions from Roads (TRAKER) method to monitor different types of roads in Baoding city before and within 1 hr after water-sprinkling and obtained the road dirtiness index (a) and PM concentration in the road environment (), to evaluate the removal efficiency for PM deposited on the road surface () and the reduction efficiency for the PM concentration in the road environment (). The results give that the for three types of roads is ranked: branch road (87%-–100%) > major arterial road (80%-83%) > minor arterial road (68%-77%), and the ranked: minor arterial road (70%) > branch road (46%-58%) > major arterial road (37%-53%). The and varied non-linearly with time and presented a quadratic curve. The average effective control time (> 0) was 62 min on the major and minor arterial roads, and much longer than 1 hr on branch roads. The values diminished completely by 72 min on average from the end of sprinkling for the three types of roads. Water-sprinkling can remove PM10 particles from the road surface and reduce their concentration in the road environment more thoroughly than PM2.5. Our findings could be helpful for controlling urban FRD emissions more efficiently and precisely. 相似文献
7.
《环境科学学报(英文版)》2024,36(2):559-569
Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon (BC), which were harmful to human health and were difficult to capture by conventional electrostatic precipitators (ESPs). In this study, nanoscale carbon black was adopted as simulated particles (SP) with similar physicochemical properties for black carbon emitted from ships (SP-BC) to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures. The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20 nm. The outlet number concentration of SP-BC under 27 kV at 130°C was three times that of the inlet. While the reduction of the flow rate could strengthen the capture of SP-BC below 20 nm, and under the combined action of low flow rate and maximum applied voltage, the collection efficiency of 20-100 nm SP-BC could exceed 90%. In addition, the escape and capture characteristics of SP-BC under long-term rapping were revealed. The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping, and the nanoscale SP-BC was trapped in the grooves after rapping. The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources. 相似文献
8.
Ruixue Wang Ning Yang Jianlong Li Li Xu Narcisse T. Tson Lin Du Wenxing Wang 《环境科学学报(英文版)》2022,34(4):149-159
Despite the heterogeneous reaction of sulfur dioxide (SO2) on mineral dust particles significantly affects the atmospheric environment, the effect of acidic gases on the formation of sulfite and sulfate from this reaction is not particularly clear. In this work, using the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique, we employed a mineral dust particle model (CaCO3) combined with NO2 and acetic acid to investigate their effects on the heterogeneous reaction of SO2 on CaCO3 particles. It was found that water vapor can promote the formation of sulfite and simulated radiation can facilitate the oxidation of sulfite to sulfate. The addition of NO2 or acetic acid to the reaction system altered the production of sulfate and sulfite accordingly. There was a synergistic effect between NO2 and SO2 that promoted the oxidation of sulfite to sulfate, and a competitive effect between acetic acid and SO2 that inhibited the formation of sulfite. Moreover, light and water vapor can also affect the heterogeneous reaction of SO2 with the coexistence of multiple gases. These findings improve our understanding of the effects of organic and inorganic gases and environmental factors on the formation of sulfite and sulfate in heterogeneous reactions. 相似文献
9.
《环境科学学报(英文版)》2023,35(11):70-82
To investigate the effect of frequently occurring mineral dust on the formation of secondary organic aerosol (SOA), 106 volatile organic compounds (VOCs), trace gas pollutants and chemical components of PM2.5 were measured continuously in January 2021 in Wuhan, Central China. The observation period was divided into two stages that included a haze period and a following dust period, based on the ratio of PM2.5 and PM10 concentrations. The average ratio of secondary organic carbon (SOC) to elemental carbon (EC) was 1.98 during the dust period, which was higher than that during the haze period (0.69). The contribution of SOA to PM2.5 also increased from 2.75% to 8.64%. The analysis of the relationships between the SOA and relative humidity (RH) and the odd oxygen (e.g., OX = O3 + NO2) levels suggested that photochemical reactions played a more important role in the enhancement of SOA production during the dust period than the aqueous-phase reactions. The heterogeneous photochemical production of OH radicals in the presence of metal oxides during the dust period was believed to be enhanced. Meanwhile, the ratios of trans-2-butene to cis-2-butene and m-/p-xylene to ethylbenzene (X/E) dropped significantly, confirming that stronger photochemical reactions occurred and SOA precursors formed efficiently. These results verified the laboratory findings that metal oxides in mineral dust could catalyse the oxidation of VOCs and induce higher SOA production. 相似文献
10.
While the transformation of antimony(Sb) in paddy soil has been previously investigated, the biogeochemical processes of highly chemical active Sb in the soil remain poorly understood. In addition, there is a lack of quantitative understanding of Sb transformation in soil. Therefore, in this study, the kinetics of exogenous Sb in paddy soils were investigated under anaerobic and aerobic incubation conditions. The dissolved Sb(V) and the Sb(V) extracted by diffusive gradient technique decreased u... 相似文献
11.
《环境科学学报(英文版)》2023,35(10):83-97
Daytime HONO photolysis is an important source of atmospheric hydroxyl radicals (OH). Knowledge of HONO formation chemistry under typical haze conditions, however, is still limited. In the Multiphase chemistry experiment in Fogs and Aerosols in the North China Plain in 2018, we investigated the wintertime HONO formation and its atmospheric implications at a rural site Gucheng. Three different episodes based on atmospheric aerosol loading levels were classified: clean periods (CPs), moderately polluted periods (MPPs) and severely polluted periods (SPPs). Correlation analysis revealed that HONO formation via heterogeneous conversion of was more efficient on aerosol surfaces than on ground, highlighting the important role of aerosols in promoting HONO formation. Daytime HONO budget analysis indicated a large missing source (with an average production rate of 0.66 ± 0.26, 0.97 ± 0.47 and 1.45 ± 0.55 ppbV/hr for CPs, MPPs and SPPs, respectively), which strongly correlated with photo-enhanced reactions ( heterogeneous reaction and particulate nitrate photolysis). Average OH formation derived from HONO photolysis reached up to (0.92 ± 0.71), (1.75 ± 1.26) and (1.82 ± 1.47) ppbV/hr in CPs, MPPs and SPPs respectively, much higher than that from photolysis (i.e., (0.004 ± 0.004), (0.006 ± 0.007) and (0.0035 ± 0.0034) ppbV/hr). Such high OH production rates could markedly regulate the atmospheric oxidation capacity and hence promote the formation of secondary aerosols and pollutants. 相似文献
12.
Heterogeneous reactions of NO2 on different surfaces play an important role in atmospheric NOx removal and HONO formation, having profound impacts on photochemistry in polluted urban areas. Previous studies have suggested that the NO2 uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during the daytime. However, the uptake behavior of NO2 varies with different surfaces, and different uptake coefficients were used or derived in different studies. To obtain a more holistic picture of heterogeneous NO2 uptake on different surfaces, a series of laboratory experiments using different flow tube reactors was conducted, and the NO2 uptake coefficients (γ) were determined on inorganic particles, sea water and urban grime. The results showed that heterogeneous reactions on those surfaces were generally weak in dark conditions, with the measured γ varied from <10?8 to 3.2 × 10?7 under different humidity. A photo-enhanced uptake of NO2 on urban grime was observed, with the obvious formation of HONO and NO from the heterogeneous reaction. The photo-enhanced γ was measured to be 1.9 × 10?6 at 5% relative humidity (RH) and 5.8 × 10?6 at 70% RH on urban grime, showing a positive RH dependence for both NO2 uptake and HONO formation. The results demonstrate an important role of urban grime in the daytime NO2-to-HONO conversion, and could be helpful to explain the unknown daytime HONO source in the polluted urban area. 相似文献
13.
《环境科学学报(英文版)》2023,35(3):524-532
The study of atmospheric polycyclic aromatic hydrocarbons (PAHs) in northeastern Tibetan Plateau with fragile ecological environment and complex atmospheric circulation system is blank. To understand the characteristics and sources of persistent organic pollutants in the atmosphere of the northeastern Tibetan Plateau, we monitored levels in the central Qilian Mountain. From 2016 to 2017, we collected 45-pair (particle + gas) samples using active air samplers to investigate the sources, transport paths, and their influencing factors. Sources of PAHs were analysed with a source diagnostic model, and atmospheric transport paths were calculated. The concentration range for ∑15PAHs was 439–4666 pg/m3, and the average was 2015 pg/m3. The PAHs in central Qilian Mountain are mainly low molecular weight (LMW) PAHs. Winter concentrations of PAHs were higher than those in summer. The transport of PAHs is mainly affected by westerlies, and there are seasonal differences. Source analysis showed that PAHs mainly came from coal and biomass combustion and vehicle emissions, with seasonal differences. This study clarifies the concentration and seasonal variation of PAHs in the northern Tibetan Plateau, which is conducive to understanding the atmospheric transport process and fate of pollutants. The background site of Qilian Mountains located in the Silk Road economic belt has the value and significance of long-term observation of pollutants. 相似文献
14.
Lanxiadi Chen Chao Peng Jingchuan Chen Jie Chen Wenjun Gu Xiaohong Jia Zhijun Wu Qiyuan Wang Mingjin Tang 《环境科学学报(英文版)》2023,35(5):210-221
Mineral dust is an important type of ice nucleating particles in the troposphere;however,the effects of heterogeneous reactions on ice nucleation (IN) activities of mineral dust remain to be elucidated.A droplet-freezing apparatus (Guangzhou Institute of Geochemistry Ice Nucleation Apparatus,GIGINA) was developed in this work to measure IN activities of atmospheric particles in the immersion freezing mode,and its performance was validated by a series of experimental characterizations.This appara... 相似文献
15.
《环境科学学报(英文版)》2023,130(8):65-74
Heterogeneous reaction of NO2 with mineral dust aerosol may play important roles in troposphere chemistry, and has been investigated by a number of laboratory studies. However, the influence of mineralogy on this reaction has not been well understood, and its impact on aerosol hygroscopicity is not yet clear. This work investigated heterogeneous reactions of NO2 (∼10 ppmv) with K-feldspar, illite, kaolinite, montmorillonite and Arizona Test Dust (ATD) at room temperature as a function of relative humidity (<1% to 80%) and reaction time (up to 24 hr). Heterogeneous reactivity towards NO2 was low for illite, kaolinite, montmorillonite and ATD, and uptake coefficients of NO2, γ(NO2), were determined to be around or smaller than 1×10−8; K-feldspar exhibited higher reactivity towards NO2, and CaCO3 is most reactive among the nine mineral dust samples considered in this and previous work. After heterogeneous reaction with NO2 for 24 hr, increase in hygroscopicity was nearly insignificant for illite, kaolinite and montmorillonite, and small but significant for K-feldspar; in addition, large increase in hygroscopicity was observed for ATD, although the increase in hygroscopicity was still smaller than CaCO3. 相似文献
16.
Deng Lin Shengrui Tong Wenqian Zhang Weiran Li Fangjie Li Chenhui Ji Gen Zhang Meifang Chen Xinran Zhang Zhen Wang Maofa Ge Xiang He 《环境科学学报(英文版)》2022,34(4):343-353
As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation. In contrast, the concentration of particulate matter in the first period (period Ⅰ) was significantly higher than that in the second period (period Ⅱ). Comparing to HONO sources in the two periods, we found that the direct vehicle emission was an essential source of the ambient HONO during both periods at night, especially in period Ⅱ. The heterogeneous reaction of NO2 was the dominant source in period Ⅰ, while the homogeneous reaction of NO with OH was more critical source at night in period Ⅱ. In the daytime, the heterogeneous reaction of NO2 was a significant source and was confirmed by the good correlation coefficients (R2) between the unknown sources (Punknown) with NO2, PM2.5, NO2 × PM2.5 in period Ⅰ. Moreover, when solar radiation and OH radicals were considered to explore unknown sources in the daytime, the enhanced correlation of Punknown with photolysis rate of NO2 and OH ( × OH) were 0.93 in period Ⅰ, 0.95 in period Ⅱ. These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals. 相似文献
17.
Air pollutants can potentially lead to nitration of allergic proteins, thus promoting sensitization of these allergens. However, little is currently known about the nitration status of house dust mite(HDM) allergens. We identified the occurrence of nitrated products of two major HDM allergens Der f 1 and Der p 1 in dust samples collected from college dormitories in eastern China and assessed their associated health risk. The results showed that both non-nitrated and nitrated forms of the two all... 相似文献
18.
Yang Ding Huanfang Huang Wei Chen Yuan Zhang Wenwen Chen Xinli Xing Shihua Qi 《环境科学学报(英文版)》2022,34(5):453-464
Long-range atmospheric transport(LRAT) plays a crucial role in the occurrence of persistent organic pollutants(POPs) in remote regions. When studying the LRAT of POPs on the Tibetan Plateau, westerly-controlled regions have received insufficient attention compared with regions influenced by the Indian monsoon or air flow from East Asia. We investigated the residual levels of POPs in soils from the eastern Pamirs and used air backward trajectory analysis to elucidate the influence of potential so... 相似文献
19.
Ning Liu Yanxia Cheng Ting Zhang Shunzhang Chen Feize Li Renwei Qing Tu Lan Yuanyou Yang Jiali Liao 《环境科学学报(英文版)》2023,35(2):915-922
As a biosorbent, algae are frequently used for the biotreatment or bioremediation of water contaminated by heavy metal or radionuclides. However, it is unclear that whether or not the biomineralization of these metal or radionuclides can be induced by algae in the process of bioremediation and what the mechanism is. In this work, Ankistrodsemus sp. has been used to treat the uranium-contaminated water, and more than 98% of uranium in the solution can be removed by the alga, when the initial uranium concentration ranges from 10 to 80 mg/L. Especially, an unusual phenomenon of algae-induced uranium biomineralization has been found in the process of uranium bioremediation and its mineralization mechanism has been explored by multiple approaches. It is worth noticing that the biomineralization of uranium induced by Ankistrodsemus sp. is significantly affected by contact time and pH. Uranium is captured rapidly on the cell surface via complexation with the carboxylate radical, amino and amide groups of the microalgae cells, which provides nucleation sites for the precipitation of insoluble minerals. Uranium stimulates Ankistrodsemus sp. to metabolize potassium ions (K+), which may endow algae with the ability to biomineralize uranium into the rose-like compreignacite (K2[(UO2)6O4(OH)6]•8H2O). As the time increased, the amorphous gradually converted into compreignacite crystals and a large number of crystals would expand over both inside and outside the cells. To the best of our knowledge, this is the first investigated microalgae with a time-dependent uranium biomineralization ability and superior tolerance to uranium. This work validates that Ankistrodsemus sp. is a promising alga for the treatment of uranium-contaminated wastewater. 相似文献
20.
Yun-Hong Zhang Wen-Xiu Pei Shuai-Shuai M Zhe Chen Yue Zhu Shu-Feng Pang 《环境科学学报(英文版)》2023,35(5):320-327
The high NO3− concentration in fine particulate matters (PM2.5) during heavy haze events has attracted much attention, but the formation mechanism of nitrates remains largely uncertain, especially concerning heterogeneous uptake of NOX by aqueous phase. In this work, the heterogeneous uptake of NO2 by sodium acetate (NaAc) droplets with different NO2 concentrations and relative humidity (RH) conditions is investigated by microscopic Fourier transform infrared spectrometer (micro-FTIR). The IR feature changes of aqueous droplets indicate the acetate depletion and nitrite formation in humid environment. This implies that acetate droplets can provide the alkaline aqueous circumstances caused by acetate hydrolysis and acetic acid (HAc) volatilization for nitrite formation during the NO2 heterogeneous uptake. Meanwhile, the nitrite formation will exhibit a pH neutralizing effect on acetate hydrolysis, further facilitating HAc volatilization and acetate depletion. The heterogeneous uptake coefficient increases from 5.2 × 10−6 to 1.27 × 10−5 as RH decreases from 90% to 60% due to the enhanced HAc volatilization. Furthermore, no obvious change in uptake coefficient with different NO2 concentrations is observed. This work may provide a new pathway for atmospheric nitrogen cycling and secondary nitrite aerosol formation. 相似文献