Heterogeneous sulphate formation in the aerosol, the cloud and the frost

2021 ◽  
Author(s):  
Hui Chen ◽  
Jiarong Li ◽  
Chao Zhu ◽  
Hartmut Herrmann ◽  
Jianmin Chen
Keyword(s):  
Atmospheric Chemistry ◽  
North China ◽  
Removal Rate ◽  
Heterogeneous Reactions ◽  
High Concentration ◽  
The North ◽  
Rapid Formation ◽  
Inorganic Composition ◽  
Total Environment ◽  
Comprehensive Study

<p>The rapid formation of sulphate is the main driving force behind the explosive growth of PM<sub>2.5</sub> in China. Our comprehensive study, combined with field observations, laboratory simulations and modelling, indicated that high concentration of hydroperoxide (H<sub>2</sub>O<sub>2</sub>) from heterogeneous reactions significantly promoted sulphate formation in winter north China. Unexpectedly, during the same campaign, a high proportion of sulphate has been observed in the frost. The chemical composition of the frost appeared to be independent of that of PM<sub>2.5</sub>. These findings can be important for the removal rate of SO<sub>2</sub> in the atmosphere and for the occult deposition of sulphate.</p><p>Also, we have investigated the contribution of oxidation channels to sulphate formation in the cloud at the summit of Mt. Tai (1545 m) in summer. Our results suggested that dissolved ozone is the dominant oxidant for the oxidation of S(IV), especially when the pH of the cloud water is less acidic (> 5.5). In recent years, with the increase of ozone concentration in China, the sulphate formation by ozone in the cloud will continue to be pronounced.</p><p> </p><p>References:</p><p>Zhu, C., Li, J.R., Chen, H., Cheng, T.T., Wen, L., Herrmann, H., Xiao, H., Chen, J.M., 2020. Inorganic composition and occult deposition of frost collected under severe polluted area in winter in the North China Plain. Science of the Total Environment 722.</p><p>Li, J.R., Zhu, C., Chen, H., Zhao, D.F., Xue, L.K., Wang, X.F., Li, H.Y., Liu, P.F., Liu, J.F., Zhang, C.L., Mu, Y.J., Zhang, W.J., Zhang, L.M., Herrmann, H., Li, K., Liu, M., Chen, J.M., 2020. The evolution of cloud and aerosol microphysics at the summit of Mt. Tai, China. Atmospheric Chemistry and Physics 20, 13735-13751.</p><p> </p>

scholarly journals In Situ Persulfate Oxidation of 1,2,3-Trichloropropane in Groundwater of North China Plain

2019 ◽  
Vol 16 (15) ◽  
pp. 2752 ◽  
Author(s):  
Hui Li ◽  
Zhantao Han ◽  
Yong Qian ◽  
Xiangke Kong ◽  
Ping Wang
Keyword(s):  
Removal Efficiency ◽  
North China Plain ◽  
North China ◽  
Removal Rate ◽  
Chlorinated Hydrocarbons ◽  
Contaminated Site ◽  
High Concentration ◽  
Chlorinated Hydrocarbon ◽  
Persulfate Oxidation

In situ injection of Fe(II)-activated persulfate was carried out to oxidize chlorinated hydrocarbons and benzene, toluene, ethylbenzene, and xylene (BTEX) in groundwater in a contaminated site in North China Plain. To confirm the degradation of contaminants, an oxidant mixture of persulfate, ferrous sulfate, and citric acid was mixed with the main contaminants including 1,2,3-trichloropropane (TCP) and benzene before field demonstration. Then the mixed oxidant solution of 6 m3 was injected into an aquifer with two different depths of 8 and 15 m to oxidize a high concentration of TCP, other kinds of chlorinated hydrocarbons, and BTEX. In laboratory tests, the removal efficiency of TCP reached 61.4% in 24 h without other contaminants but the removal rate was decreased by the presence of benzene. Organic matter also reduced the TCP degradation rate and the removal efficiency was only 8.3% in 24 h. In the field test, as the solution was injected, the oxidation reaction occurred immediately, accompanied by a sharp increase of oxidation–reduction potential (ORP) and a decrease in pH. Though the concentration of pollutants increased due to the dissolution of non-aqueous phase liquid (NAPL) at the initial stage, BTEX could still be effectively degraded in subsequent time by persulfate in both aquifers, and their removal efficiency approached 100%. However, chlorinated hydrocarbon was relatively difficult to degrade, especially TCP, which had a relatively higher initial concentration, only had a removal efficiency of 30%–45% at different aquifers and monitoring wells. These finding are important for the development of injection technology for chlorinated hydrocarbon and BTEX contaminated site remediation.

Seasonal effects of additional HONO sources and the heterogeneous reactions of N2O5 on nitrate in the North China Plain

2020 ◽  
Author(s):  
Yu Qu ◽  
Junling An
Keyword(s):  
North China Plain ◽  
North China ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Seasonal Effects ◽  
Weather Research And Forecasting ◽  
The North ◽  
The North China Plain ◽  
Four Seasons ◽  
Hydrolysis Of

<p>We coupled the heterogeneous hydrolysis of N<sub>2</sub>O<sub>5</sub> into the newly updated Weather Research and Forecasting model with Chemistry (WRF-Chem) to reveal the relative importance of the hydrolysis of N<sub>2</sub>O<sub>5</sub> and additional nitrous acid (HONO) sources for the formation of nitrate during high PM<sub>2.5</sub> events in the North China Plain (NCP) in four seasons. The results showed that additional HONO sources produced the largest nitrate concentrations in winter and negligible nitrates in summer, leading to a 10% enhancement of a PM<sub>2.5</sub> peak in southern Beijing and a 15% enhancement in southeastern Hebei in winter. In contrast, the hydrolysis of N<sub>2</sub>O<sub>5</sub> produced high nitrate in summer and low nitrate in winter, with the largest contribution of nearly 20% for a PM<sub>2.5</sub> peak in southeastern Hebei in summer. During PM<sub>2.5 </sub>explosive growth events, the additional HONO sources played a key role in nitrate increases in southern Beijing and southwestern Hebei in winter, whereas the hydrolysis of N<sub>2</sub>O<sub>5 </sub>contributed the most to a rapid increase in nitrate in other seasons. HONO photolysis produced more hydroxyl radicals, which were greater than 1.5 μg m<sup>-3</sup> h<sup>-1</sup> in the early explosive stage and led to a rapid nitrate increase at the southwestern Hebei sites in winter, while the heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> contributed greatly to a significant increase in nitrate in summer. The above results suggest that the additional HONO sources and the heterogeneous hydrolysis of N<sub>2</sub>O<sub>5</sub> contributed the most to nitrate formation in NCP in winter and summer, respectively.</p>

scholarly journals Haze pollution in winter and summer in Zibo, a heavily industrialized city neighboring the Jin-Jin-Ji area of China: source, formation, and implications

2018 ◽  
Author(s):  
Hui Li ◽  
Fengkui Duan ◽  
Yongliang Ma ◽  
Kebin He ◽  
Lidan Zhu ◽  
...  
Keyword(s):  
North China ◽  
Control Policy ◽  
Photochemical Activity ◽  
Heterogeneous Reactions ◽  
Air Pollution Control ◽  
The North ◽  
Haze Pollution ◽  
High Concentrations ◽  
Pollution Control Policy ◽  
Haze Days

Abstract. Continuous field observations of haze pollution were conducted in winter and summer during 2015 in Zibo, a highly industrialized city in the North China Plain that is adjacent to the Jing-Jin-Ji area. PM2.5 concentration averaged 146.7 ± 85.8 and 82.2 ± 44.3 μg m−3 in winter and summer, respectively. The chemical component contributions to PM2.5 showed obvious seasonal variation. Organics were high in winter, but secondary inorganic aerosols (SIA) were high in summer. From non-haze to haze days, the concentration of SIA increased, implying an important role of secondary processes in the evolution process of the pollution. The diurnal behavior of several pollutants during haze days appeared to fluctuate more, but during non-haze days, it was much more stable, suggesting that complex mechanisms are involved. Specifically, gaseous precursors, mixed layer height (MLH), photochemical activity, and relative humidity (RH) also played important roles in the diurnal variation of the pollutants. Normally, larger gaseous precursor concentrations, photochemical activity, and RH, and lower MLH favored high concentrations. In winter, the formation of sulfate was mainly influenced by RH, indicating the importance of heterogeneous reactions in its formation. In contrast, in summer, photochemistry and SO2 concentration had the largest impact on the sulfate level. We found that Zibo was an ammonia-rich city, especially in winter, meaning that the formation of nitrate was through homogeneous reactions between HNO3 and NH3 in the gas phase, followed by partitioning into the particle phase. The RH, NO2, and Excess NH4+ were the main influencing factors for nitrate in winter, whereas Excess NH4+, RH, and temperature were the key factors in summer. The secondary organic carbon (SOC) level depended on the MLH and photochemistry. In winter, the effect of the MLH was stronger than that of photochemistry, but a reversed situation occurred in summer because of the intensive photochemistry. Our work suggested that the inter-transport between Zibo, one of the most polluted cities in north China, and its adjacent areas should be taken into account when formulating air pollution control policy.

scholarly journals Significant increase of summertime ozone at Mount Tai in Central Eastern China

2016 ◽  
Vol 16 (16) ◽  
pp. 10637-10650 ◽  
Author(s):  
Lei Sun ◽  
Likun Xue ◽  
Tao Wang ◽  
Jian Gao ◽  
Aijun Ding ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Production Efficiency ◽  
North China ◽  
Climate Model ◽  
Eastern China ◽  
Linear Regression Analysis ◽  
Ozone Production ◽  
The North ◽  
Short Period ◽  
Central Eastern

Abstract. Tropospheric ozone (O3) is a trace gas playing important roles in atmospheric chemistry, air quality and climate change. In contrast to North America and Europe, long-term measurements of surface O3 are very limited in China. We compile available O3 observations at Mt. Tai – the highest mountain over the North China Plain – during 2003–2015 and analyze the decadal change of O3 and its sources. A linear regression analysis shows that summertime O3 measured at Mt. Tai has increased significantly by 1.7 ppbv yr−1 for June and 2.1 ppbv yr−1 for the July–August average. The observed increase is supported by a global chemistry-climate model hindcast (GFDL-AM3) with O3 precursor emissions varying from year to year over 1980–2014. Analysis of satellite data indicates that the O3 increase was mainly due to the increased emissions of O3 precursors, in particular volatile organic compounds (VOCs). An important finding is that the emissions of nitrogen oxides (NOx) have diminished since 2011, but the increase of VOCs appears to have enhanced the ozone production efficiency and contributed to the observed O3 increase in central eastern China. We present evidence that controlling NOx alone, in the absence of VOC controls, is not sufficient to reduce regional O3 levels in North China in a short period.

scholarly journals SO<sub>2</sub> noontime peak phenomenon in the North China Plain

2014 ◽  
Vol 14 (5) ◽  
pp. 5653-5685
Author(s):  
W. Y. Xu ◽  
C. S. Zhao ◽  
L. Ran ◽  
W. L. Lin ◽  
P. Yan ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
North China Plain ◽  
North China ◽  
Transport Processes ◽  
Cloud Physics ◽  
Mountain Valley ◽  
The North ◽  
Diurnal Patterns ◽  
The North China Plain ◽  
Gas Phase Oxidation

Abstract. Frequent SO2 noontime peak phenomenon was discovered in a detailed analysis on the SO2 concentrations in the North China Plain (NCP). The possible causes and their contributions are analysed. The impacts of such a phenomenon on the sulphur cycle were studied and the implications of the phenomenon for atmospheric chemistry, cloud physics and climate were discussed. Different from the common SO2 diurnal patterns with high nighttime concentrations, NCP witnessed high frequencies of SO2 noontime peaks, with an occurrence frequency of 50–72% at the four stations. Down-mixing of elevated pollution layers, plume transport processes, mountain-valley-winds and fog/high RH haze events were the possible causes. The contribution of each process varies from each other and from station to station, however, neither of those four processes can be neglected. SO2 peaks occurring during noontime instead of nighttime will lead to a 13–35% increase in sulphur dry deposition, 9–23% increase in gas phase oxidation and 8–33% increase in aqueous phase conversions, which will increase the hygroscopicity and the light scattering of aerosols, thus having important impacts on atmospheric chemistry, cloud physics and climate.

scholarly journals Rapid formation of a severe regional winter haze episode over a mega-city cluster on the North China Plain

2017 ◽  
Vol 223 ◽  
pp. 605-615 ◽  
Author(s):  
Jie Li ◽  
Huiyun Du ◽  
Zifa Wang ◽  
Yele Sun ◽  
Wenyi Yang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
The North ◽  
The North China Plain ◽  
Rapid Formation ◽  
Haze Episode ◽  
City Cluster

scholarly journals Is water vapor a key player of the wintertime haze in North China Plain?

2019 ◽  
Vol 19 (13) ◽  
pp. 8721-8739 ◽  
Author(s):  
Jiarui Wu ◽  
Naifang Bei ◽  
Bo Hu ◽  
Suixin Liu ◽  
Meng Zhou ◽  
...  
Keyword(s):  
Water Vapor ◽  
North China Plain ◽  
North China ◽  
Temporal Variations ◽  
Effective Radius ◽  
Heterogeneous Reactions ◽  
Hygroscopic Growth ◽  
Near Surface ◽  
The North ◽  
Haze Pollution

Abstract. Water vapor has been proposed to amplify the severe haze pollution in China by enhancing the aerosol–radiation feedback (ARF). Observations have revealed that the near-surface PM2.5 concentrations ([PM2.5]) generally exhibit an increasing trend with relative humidity (RH) in the North China Plain (NCP) during 2015 wintertime, indicating that the aerosol liquid water (ALW) caused by hygroscopic growth could play an important role in the PM2.5 formation and accumulation. Simulations during a persistent and heavy haze pollution episode from 5 December 2015 to 4 January 2016 in the NCP were conducted using the WRF-Chem Model to comprehensively quantify contributions of the ALW effect to near-surface [PM2.5]. The WRF-Chem Model generally performs reasonably well in simulating the temporal variations in RH against measurements in the NCP. The factor separation approach (FSA) was used to evaluate the contribution of the ALW effect on the ARF, photochemistry, and heterogeneous reactions to [PM2.5]. The ALW not only augments particle sizes to enhance aerosol backward scattering but also increases the effective radius to favor aerosol forward scattering. The contribution of the ALW effect on the ARF and photochemistry to near-surface [PM2.5] is not significant, being generally within 1.0 µg m−3 on average in the NCP during the episode. Serving as an excellent substrate for heterogeneous reactions, the ALW substantially enhances the secondary aerosol (SA) formation, with an average contribution of 71 %, 10 %, 26 %, and 48 % to near-surface sulfate, nitrate, ammonium, and secondary organic aerosol concentrations. Nevertheless, the SA enhancement due to the ALW decreases the aerosol optical depth and increases the effective radius to weaken the ARF, reducing near-surface primary aerosols. The contribution of the ALW total effect to near-surface [PM2.5] is 17.5 % on average, which is overwhelmingly dominated by enhanced SA. Model sensitivities also show that when the RH is less than 80 %, the ALW progressively increases near-surface [PM2.5] but commences to decrease when the RH exceeds 80 % due to the high occurrence frequencies of precipitation.

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