scholarly journals Characteristics, sources, and reactions of nitrous acid during winter at an urban site in the Central Plains Economic Region in China

2020 ◽  
Vol 20 (11) ◽  
pp. 7087-7102
Author(s):  
Qi Hao ◽  
Nan Jiang ◽  
Ruiqin Zhang ◽  
Liuming Yang ◽  
Shengli Li
Keyword(s):  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Urban Site ◽  
Steady Increase ◽  
Homogeneous Reaction ◽  
Economic Region ◽  
Central Plains ◽  
Mean Values ◽  
Budget Analysis ◽  
The Mean

Abstract. Nitrous acid (HONO) in the core city of the Central Plains Economic Region in China was measured using an ambient ion monitor from 9 to 31 January 2019. Measurement time intervals were classified into the following periods in accordance with the daily mean values of PM2.5: clean days (CDs), polluted days (PDs), and severely polluted days (SPDs). The HONO concentrations during CD, PD, and SPD periods were 1.2, 2.3, and 3.7 ppbv, respectively. The contributions of the homogeneous reaction, heterogeneous conversion, and direct emissions to HONO sources varied under different pollution levels. The mean values of the net HONO production of the homogeneous reaction (POH+NOnet) in CD, PD, and SPD periods were 0.13, 0.26, and 0.56 ppbv h−1, respectively. The average conversions of NO2 (CHONO) in CD, PD, and SPD periods were 0.72×10-2, 0.64×10-2, and 1.54×10-2 h−1, respectively, indicating that the heterogeneous conversion of NO2 was less important than the homogeneous reaction. Furthermore, the net production of the homogeneous reaction may have been the main factor in the increase of HONO under high-NOx conditions (i.e., when the concentration of NO was higher than that of NO2) at nighttime. Daytime HONO budget analysis showed that the mean values of the unknown source (Punknown) during CD, PD, and SPD periods were 0.26, 0.40, and 1.83 ppbv h−1, respectively. The values of POH+NOnet, CHONO, and Punknown in the SPDs period were comparatively larger than those in other periods, indicating that HONO participated in many reactions. The proportions of nighttime HONO sources also changed during the entire sampling period. Direct emissions and a heterogeneous reaction controlled HONO production in the first half of the night and provided a contribution that is larger than that of the homogeneous reaction. The proportion of homogenization gradually increased in the second half of the night due to the steady increase in NO concentrations. The hourly level of HONO abatement pathways, except for OH + HONO, was at least 0.22 ppbv h−1 in the SPDs period. The cumulative frequency distribution of the HONOemission∕HONO ratio (less than 20 %) was approximately 77 %, which suggested that direct emission was not important. The heterogeneous HONO production increased when the relative humidity (RH) increased, but it decreased when RH increased further. The average HONO∕NOx ratio (4.9 %) was more than twice the assumed globally averaged value (2.0 %).

scholarly journals Characteristics, sources and reactions of nitrous acid during winter in the core city of the Central Plains Economic Region in China via high-time-resolution online measurements

2019 ◽  
Author(s):  
Qi Hao ◽  
Nan Jiang ◽  
Ruiqin Zhang ◽  
Liuming Yang ◽  
Shengli Li
Keyword(s):  
Nitrous Acid ◽  
High Time Resolution ◽  
Homogeneous Reaction ◽  
Economic Region ◽  
Central Plains ◽  
Mean Values ◽  
The Core ◽  
Budget Analysis ◽  
Direct Emission ◽  
The Mean

Abstract. Nitrous acid (HONO) in the core city of the Central Plains Economic Region was measured using an ambient ion monitor from January 9 to 31, 2019. Measurement time intervals were classified into the following periods in accordance with the daily mean values of PM2.5: clean days (CD), pollution days (PD), and severe pollution days (SPD). The HONO concentrations during CD, PD, and SPD were 1.2, 2.3, and 3.7 ppbv, respectively. The contribution of the three sources varied under different pollution levels. The mean values of the net HONO production of the homogeneous reaction (P(OH+NO)net) in CD, PD, and SPD periods were 0.51, 1.03, and 2.18 ppbv h−1, respectively. The average conversions of NO2 (CHONO) in CD, PD, and SPD periods were 0.72 × 10−2, 0.64 × 10−2, and 1.54 × 10−2 ppbv h−1, respectively, indicating that the heterogeneous conversion of NO2 was unimportant. Furthermore, the net production of the homogeneous reaction may have been the main factor for the increase in HONO under high-NOX conditions (i.e., the concentration of NO was higher than that of NO2) at nighttime. Daytime HONO budget analysis showed that the mean values of the unknown source (Punknown) during CD, PD, and SPD periods were 0.26, 0.40, and 1.83 ppbv h−1, respectively. The values of P(OH+NO)net, CHONO, and Punknown in the SPD period were comparatively larger than those in other periods, indicating that HONO participated in many reactions. The proportions of nighttime HONO sources also changed during the entire sampling period. Direct emission and a heterogeneous reaction controlled HONO production in the first half of the night and provided a contribution larger than that of the homogeneous reaction. The proportion of homogenization gradually increased in the second half of the night due to the steady increase in NO concentration. The hourly abatement level of HONO abatement pathways, except for OH + HONO, should be at least 1.47 ppbv h−1 in the SPD period. The cumulative frequency distribution of the HONOemission / HONO ratio (less than 20 %) was approximately 76.7 %, which suggests that direct emission was important. The heterogeneous HONO production increased when the relative humidity (RH) increased from 52 % to 77 %, but it decreased when RH increased further. The average HONO / NOX ratio (4.9 %) was more than twice the assumed globally averaged value (2.0 %).

Budget of nitrous acid (HONO) and its impacts on atmospheric oxidation capacity at an urban site in Guangzhou of China

2021 ◽  
Author(s):  
Yihang Yu ◽  
Peng Cheng ◽  
Huirong Li ◽  
Wenda Yang ◽  
Baobin Han ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Emission Rate ◽  
Chemical Mechanism ◽  
Atmospheric Oxidation ◽  
Urban Site ◽  
Homogeneous Reaction ◽  
Pearl River Delta Region ◽  
Oxidation Capacity ◽  
High Concentrations ◽  
The Impact

<p>Nitrous acid (HONO) can produce hydroxyl radicals (OH) by photolysis and plays an important role in atmospheric photochemistry. Over the years, high concentrations of HONO have been found in the Pearl River Delta region (PRD), which may be one of the reasons for the high atmospheric oxidation capacity. A comprehensive atmospheric observation was conducted at an urban site in Guangzhou from 27 September to 9 November 2018. During the period, HONO ranged from 0.02 to 4.43 ppbv with an average of 0.74±0.70 ppbv. The combustion emission ratio (HONO/NOx) of 0.9±0.4% was derived from 11 fresh plumes. The primary emission rate of HONO during night was calculated with the emission source inventory data to be between 0.04±0.02 and 0.30±0.15 ppbv/h. And the HONO produced by the homogeneous reaction of OH+NO at night was 0.26±0.08 ppbv/h, which can be seemed as secondary results from primary emission. They were both much higher than the increase rate of HONO (0.02 ppbv/h) during night. Soil emission rate of HONO at night was calculated to be 0.019±0.0003 ppbv/h. Deposition was the dominant removal process of HONO during night, and a deposition rate of at least 2.5 cm/s is required to balance the direct emissions and OH+NO reaction. Correlation analysis shows that NH<sub>3</sub> and relative humidity (RH) may participate in the heterogeneous transformation from NO<sub>2</sub> to HONO during night. In the daytime, the average primary emission P<sub>emis</sub> was 0.12±0.01 ppbv/h, and the homogeneous reaction P<sub>OH+NO</sub> was 0.79±0.61 ppbv/h, which was even larger than the unknown sources P<sub>Unknown</sub> (0.65±0.46 ppbv/h). The results showed that the direct and indirect contributions of primary emission to HONO are great at the site, both during daytime and nighttime. Similar to previous studies, P<sub>Unknown</sub> was suggested to be related to the photo-enhanced reaction of NO<sub>2</sub>. The mean OH production rates by photolysis of HONO and O<sub>3</sub> were 3.7×10<sup>6</sup> cm<sup>-3</sup>·s<sup>-1</sup> and 4.9×10<sup>6</sup> cm<sup>-3</sup>·s<sup>-1</sup>, respectively. We further studied the impact of HONO on the atmospheric oxidation by a Master Chemical Mechanism (MCM) box model. When constraining observed HONO in the model, OH and O<sub>3 </sub>increased 59% and 68.8% respectively, showing a remarkable contribution of HONO to the atmospheric oxidation of Guangzhou.</p><p> </p>

Semi-quantitative understanding of source contribution to nitrous acid (HONO) based on 1 year of continuous observation at the SORPES station in eastern China

2020 ◽  
Author(s):  
Yuliang Liu
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Total Concentration ◽  
Eastern China ◽  
Mean Value ◽  
Budget Analysis ◽  
Conversion Frequency ◽  
Yearly Average ◽  
Quantitative Understanding

<p>Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), has long been recognized as of significance to atmospheric chemistry, but its sources are still debated. In this study, we conducted continuous measurement of HONO from November 2017 to November 2018 at the SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was <span>0.69±0.58</span> ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 1.16 ppb h<span><sup>−1</sup></span>. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO to <span>NO<sub><em>x</em></sub></span> were derived from 55 fresh plumes (<span>NO∕NO<sub><em>x</em></sub></span> > 0.85), with a mean value of 0.79 %. During the nighttime, the chemistry of HONO was found to depend on RH, and the heterogeneous reaction of <span>NO<sub>2</sub></span> on an aerosol surface was presumably responsible for HONO production. The average nighttime <span>NO<sub>2</sub></span>-to-HONO conversion frequency (<span><em>C</em><sub>HONO</sub></span>) was determined to be <span>0.0055±0.0032</span> h<span><sup>−1</sup></span> from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced, with an average <span><em>P</em><sub>unknown</sub></span> of 1.04 ppb h<span><sup>−1</sup></span>, based on a semi-quantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Besides the burning-emitted HONO (accounting for about 23 % of the total concentration), the contribution of HONO formed heterogeneously on ground surfaces to measured HONO was an approximately constant proportion of 36 % throughout the year. The soil emission revealed clear seasonal variation and contributed up to 40 % of observed HONO in July and August. A higher propensity for generating HONO on aerosol surfaces occurred in severe hazes (accounting for 40 % of the total concentration in January). Our results highlight ever-changing contributions of HONO sources and encourage more long-term observations to evaluate the contributions from varied sources.</p>

scholarly journals Semi-quantitative understanding of source contribution to nitrous acid (HONO) based on 1 year of continuous observation at the SORPES station in eastern China

2019 ◽  
Vol 19 (20) ◽  
pp. 13289-13308 ◽  
Author(s):  
Yuliang Liu ◽  
Wei Nie ◽  
Zheng Xu ◽  
Tianyi Wang ◽  
Ruoxian Wang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Total Concentration ◽  
Eastern China ◽  
Mean Value ◽  
Budget Analysis ◽  
Conversion Frequency ◽  
Yearly Average ◽  
Quantitative Understanding

Abstract. Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), has long been recognized as of significance to atmospheric chemistry, but its sources are still debated. In this study, we conducted continuous measurement of HONO from November 2017 to November 2018 at the SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was 0.69±0.58 ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 1.16 ppb h−1. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO to NOx were derived from 55 fresh plumes (NO∕NOx > 0.85), with a mean value of 0.79 %. During the nighttime, the chemistry of HONO was found to depend on RH, and heterogeneous reaction of NO2 on an aerosol surface was presumably responsible for HONO production. The average nighttime NO2-to-HONO conversion frequency (CHONO) was determined to be 0.0055±0.0032 h−1 from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced, with an average Punknown of 1.04 ppb h−1, based on a semi-quantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Besides the burning-emitted HONO (accounting for about 23 % of the total concentration), the contribution of HONO formed heterogeneously on ground surfaces to measured HONO was an approximately constant proportion of 36 % throughout the year. The soil emission revealed clear seasonal variation and contributed up to 40 % of observed HONO in July and August. A higher propensity for generating HONO on aerosol surfaces occurred in severe hazes (accounting for 40 % of the total concentration in January). Our results highlight ever-changing contributions of HONO sources and encourage more long-term observations to evaluate the contributions from varied sources.

scholarly journals Contributions of different sources to nitrous acid (HONO) at the SORPES station in eastern China: results from one-year continuous observation

2019 ◽  
Author(s):  
Yuliang Liu ◽  
Wei Nie ◽  
Zheng Xu ◽  
Tianyi Wang ◽  
Ruoxian Wang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Heterogeneous Reaction ◽  
Eastern China ◽  
Early Morning ◽  
Mean Value ◽  
Budget Analysis ◽  
Yearly Average ◽  
Heterogeneous Formation ◽  
One Year

Abstract. Nitrous acid (HONO), a reservoir of the hydroxyl radical (OH), has been long-standing recognized to be of significant importance to atmospheric chemistry, but its sources are still debate. In this study, we conducted continuous measurement of HONO from November 2017 to November 2018 at SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was 0.69 ± 0.58 ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 0.90 ± 0.27 ppb/h. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO and NOx were derived from 55 fresh plumes (NO / NOx > 0.85), with a mean value of 0.79 %. The well-defined seasonal and diurnal patterns with clear wintertime and early morning concentration peaks of both HONO and NOx indicate that NOx is the critical precursor of HONO. During the nighttime, the chemistry of HONO was found to depend on RH, and heterogeneous reaction of NO2 on aerosol surface was presumably responsible for HONO production. The average nighttime NO2-to-HONO conversion frequency (CHONO) was determined to be 0.0055 ± 0.0032 h−1 from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced with an average Punknown of 1.13 ± 0.95 ppb h−1, based on a semiquantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Except for burning-emitted HONO (approximately 23 % of total measured HONO), the contribution of heterogeneous formation on ground surfaces was an approximately constant proportion of 36 % throughout the year. The soil emission revealed clear seasonal variation, and contributed up to 40 % of observed HONO in July and August. A higher propensity for generating HONO on aerosol surface occurred in heavily polluted period (about 40 % of HONO in January). Our results highlight ever-changing contributions of HONO sources, and encourage more long-term observations to evaluate the contribution from varied sources.

scholarly journals Budget of nitrous acid (HONO) and its impacts on atmospheric oxidation capacity at an urban site in the fall season of Guangzhou, China

2021 ◽  
Author(s):  
Yihang Yu ◽  
Peng Cheng ◽  
Huirong Li ◽  
Wenda Yang ◽  
Baobin Han ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Deposition Velocity ◽  
Chemical Mechanism ◽  
Atmospheric Oxidation ◽  
Urban Site ◽  
Enhancement Effect ◽  
Homogeneous Reaction ◽  
Pearl River Delta Region ◽  
Fall Season ◽  
Oxidation Capacity

Abstract. Nitrous acid (HONO) can produce hydroxyl radicals (OH) by photolysis and plays an important role in atmospheric photochemistry. Over the years, high concentrations of HONO have been observed in the Pearl River Delta region (PRD) of China, which may be one reason for the elevated atmospheric oxidation capacity. A comprehensive atmospheric observation campaign was conducted at an urban site in Guangzhou from 27 September to 9 November 2018. During the period, HONO was measured from 0.02 to 4.43 ppbv with an average of 0.74 ± 0.70 ppbv. The emission ratios (HONO/NOx) of 0.9 ± 0.4 % were derived from 11 fresh plumes. The primary emission rates of HONO at night were calculated to be between 0.04 ± 0.02 ppbv h−1 and 0.30 ± 0.15 ppbv h−1 based on a high-resolution emission inventory. The HONO formation rate by the homogeneous reaction of OH + NO at night was 0.26 ± 0.08 ppbv h−1, which can be seen as secondary results from primary emission. They were both much higher than the increase rate of HONO (0.02 ppbv h−1) during night. Soil emission rate of HONO at night was calculated to be 0.019 ± 0.001 ppbv h−1. Assuming dry deposition as the dominant removal process of HONO at night, and a deposition velocity of at least ~2.5 cm s−1 is required to balance the direct emissions and OH + NO reaction. Correlation analysis shows that NH3 and relative humidity (RH) may participate in the heterogeneous transformation from NO2 to HONO at night. In the daytime, the average primary emission Pemis was 0.12 ± 0.01 ppbv h−1, and the homogeneous reaction POH + NO was 0.79 ± 0.61 ppbv h−1, larger than the unknown sources PUnknown (0.65 ± 0.46 ppbv h−1). These results suggest primary emissions as a key factor affecting HONO at our site, both during daytime and nighttime. Similar to previous studies, the daytime unknown source of HONO, PUnknown, appeared to be related to the photo-enhanced conversion of NO2. The daytime average OH production rates by photolysis of HONO was 3.7 × 106 cm−3 s−1, lower than that from O1D + H2O at 4.9 × 106 cm−3 s−1. Simulations of OH and O3 with the Master Chemical Mechanism (MCM) box model suggested strong enhancement effect of HONO on OH and O3 by 59 % and 68.8 %, respectively, showing a remarkable contribution of HONO to the atmospheric oxidation in the fall season of Guangzhou.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

Comparative Study of Intranasal, Subcutaneous and Intravenous Administration of Desamino-D-Arginine Vasopressin (DDAVP)

1986 ◽  
Vol 55 (01) ◽  
pp. 108-111 ◽  
Author(s):  
M Köhler ◽  
P Hellstern ◽  
C Miyashita ◽  
G von Blohn ◽  
E Wenzel
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Factor Xii ◽  
Additional Advantage ◽  
Mean Values ◽  
Routes Of Administration ◽  
The Mean ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThis study was performed to evaluate the influence of different routes of administration on the efficacy of DDAVP treatment. Ten healthy volunteers received DDAVP intranasally (i.n.), subcutaneously (s.c.) and intravenously (i.v.) in a randomized cross-over trial. Factor XII and high molecular weight (HMW)-kininogen levels increased only slightly after DDAVP administration. The mean increase of factor VIII: C was 3.1 (i. v.), 2.3 (s. c.), and 1.3 (i.n.) - fold over baseline. Ristocetin cofactor (von Willebrand factor antigen) increased 3.1 (2.5), 2.0 (2.3) and 1.2 (1.2) - fold over baseline mean values after i.v., s.c. and i.n. DDAVP, respectively. The half-disappearance time of factor VIII and von Willebrand factor (vWF) after DDAVP ranged from five (factor VIII: C) to eight hours (vWF). The mean increase of fibrinolytic activity was more pronounced after i.v. DDAVP. The antidiuretic effect was moderate with no apparent differences between the routes of application. This study provides further evidence that both i.v. and s.c. DDAVP administration result in an appropriate and reliable stimulation of haemostasis. An additional advantage of s. c. administration is its suitability for home treatment.

Comparative Study of effectiveness of mobilization with movement (MWM) and End range mobilization (ERM) techniques in frozen shoulder

2018 ◽  
Vol 4 (4) ◽  
pp. 519-522
Author(s):  
Jeyakumar S ◽  
Jagatheesan Alagesan ◽  
T.S. Muthukumar
Keyword(s):  
Range Of Motion ◽  
Frozen Shoulder ◽  
Type I ◽  
Mean Values ◽  
Functional Activities ◽  
Group A ◽  
The Mean ◽  
Group B

Background: Frozen shoulder is disorder of the connective tissue that limits the normal Range of motion of the shoulder in diabetes, frozen shoulder is thought to be caused by changes to the collagen in the shoulder joint as a result of long term Hypoglycemia. Mobilization is a therapeutic movement of the joint. The goal is to restore normal joint motion and rhythm. The use of mobilization with movement for peripheral joints was developed by mulligan. This technique combines a sustained application of manual technique “gliding” force to the joint with concurrent physiologic motion of joint, either actively or passively. This study aims to find out the effects of mobilization with movement and end range mobilization in frozen shoulder in Type I diabetics. Materials and Methods: 30 subjects both male and female, suffering with shoulder pain and clinically diagnosed with frozen shoulder was recruited for the study and divided into two groups with 15 patients each based on convenient sampling method. Group A patients received mobilization with movement and Group B patients received end range mobilization for three weeks. The outcome measurements were SPADI, Functional hand to back scale, abduction range of motion using goniometer and VAS. Results: The mean values of all parameters showed significant differences in group A as compared to group B in terms of decreased pain, increased abduction range and other outcome measures. Conclusion: Based on the results it has been concluded that treating the type 1 diabetic patient with frozen shoulder, mobilization with movement exercise shows better results than end range mobilization in reducing pain and increase functional activities and mobility in frozen shoulder.

Sign in / Sign up

Export Citation Format

Share Document