High NOx Concentrations Research Articles

Interplay of nitric oxide metabolites and markers of endothelial injury, inflammation, and vascular disease in the spectrum of advanced chronic kidney disease.

Chronic kidney disease is linked to cardiovascular morbidity; therefore, relevant biomarkers are widely investigated. We aimed to assess the relationship between nitric oxide (as measured by its metabolites, NOx), a key endothelial molecule, with markers of endothelial dysfunction, inflammation, antioxidant status, and mineral disorders as well as histologically assessed vascular calcification in uremic and hemodialysis patients with chronic kidney disease. Plasma and serum samples were obtained from 62 patients with renal failure. NOx was assessed by the Griess method, while the other biomarkers were measured by the immunoenzymatic assay. Morphological analysis of arterial calcification was performed in a blinded, semiquantitative manner. Common carotid intima‑media thickness and atherosclerotic plaques were assessed by ultrasonography. In the simple analysis, NOx levels correlated positively with the parameters of renal function, mineral metabolism, endothelial injury, and inflammation. NOx predicted carotid intima‑media thickness in simple (P = 0.014) and multiple analysis (P = 0.036) adjusted for the Framingham risk score, C‑reactive protein, serum creatinine, and parathormone. The occurrence of atherosclerotic plaques in the common carotid artery was correlated with higher NOx concentrations (P = 0.021). In chronic renal failure, NOx is associated with surrogate markers of atherosclerosis, even after adjustment for traditional cardiovascular risk factors, inflammation, and renal function, but not with the presence or grade of medial arterial calcification. Endothelial injury, inflammation, and mineral metabolism markers are associated with NOx levels, though a causal link requires further study.

Mixing state and light absorption enhancement of black carbon aerosols in summertime Nanjing, China

Direct in-situ measurements of aerosol mixing state, optical properties, and chemical composition were performed in summertime of 2014 at Nanjing, China. Aerosols were predominantly internally mixed, with an average effective density of 1.30–1.63 g cm−3 for 50–230 nm particles, increasing with size. Externally mixed, relatively fresh black carbon (BC) was only episodically observed, with a second mode peaking at 0.51–0.91 g cm−3. For particles of 110, 140, 185 and 230 nm, BC accounted for 1.7 ± 1.2%, 4.8 ± 3.0%, 5.3 ± 3.3%, and 5.1 ± 3.3% of the particle mass, while being present in 26.4 ± 5.3%, 58.1 ± 27.7%, 59.8 ± 25.4%, and 62.4 ± 27.9% of the particle number concentration, indicating that BC was heavily coated and may contribute significantly to atmospheric aerosol population. Substantial BC absorption enhancement was observed with Eabs of 1.41 ± 0.39, 1.42 ± 0.40 and 1.35 ± 0.38 at 405, 532 and 781 nm, respectively. High volatile aerosol components, in particular nitrate, were found to play vital roles in BC's absorption enhancement. High Eabs values were associated with elevated NOx and RH. A clear diurnal pattern was observed for Eabs supporting a significant impact from traffic emissions, which stood in contrast with previous studies reporting very thin coating and negligible absorption enhancement for traffic emitted BC. High concentrations of NOx co-emitted with BC from traffic sources and its conversion to particulate nitrate likely contributed to the aging and increased absorption of BC particles, which was even enhanced under high RH above the deliquescence point of ammonium nitrate. Therefore, our results indicated that the mitigation of NOx emissions from traffic was critical for reducing the positive radiative forcing induced by BC, especially under high RH conditions.

Analysis of pollutant emissions during circulating fluidized bed combustion of sewage sludge

In this paper, pollutant emissions during air-CFB combustion of sewage sludge, wheat straw, Scots pine and bituminous coal are discussed. Combustion tests were carried out in a bench-scale circulating fluidized-bed reactor. Time-resolved profiles of emitted pollutants (NO, N2O, NO2, SO2 and CO) are presented and analyzed. The effects fuel type on gaseous emissions are evaluated. Due to the high contents of nitrogen, sulphur and ash in sewage sludge high concentrations of NOx and SO2 may be expected in the flue gas.

Emissions from Combustion of Second-Generation Biodiesel Produced from Seeds of Date Palm Fruit (Phoenix dactylifera L.)

Transportation is a vital necessity without which the entire world would come to a standstill. The fossil fuels used to power transportation are consumed at rates of approximately 100,000 times their rate of natural formation, and their consumption subjects the human environment and ecosystem to significant damage. As substitutes for fossil-based diesel, second-generation biodiesels can eliminate many of the challenges concerning first-generation biodiesels in terms of their high cost and the food versus fuel debate. The seeds of the date palm tree have significant oil content and are a promising prospective energy source. This study investigated the potential environmental benefits of this biofuel in terms of diesel tailpipe emission reduction. The various blends of palm date biodiesel were produced and matched to fuel standard requirements, resulting in four standard-compatible blends that were tested in a diesel engine at varying operating conditions for speed and load. Although the biodiesel emissions had lower concentrations of CO2, CO, and HC relative to fossil diesel, higher concentrations of NOx were detected. The results suggest that date-seed biodiesel could become a sustainable energy source for the transport sector, although further technical and economic investigations will be required before its wide deployment.

NO Oxidation with NaClO, NaClO2, and NaClO3 Solution Using Electron Beam and a One Stage Absorption System

The reduction of high concentrations of NOX and SO2 has been studied for the simulation of NOX and SO2 removal from off-gases generated by diesel engines in which heavy fuel oil is usually used. The combination of electron beam (EB) and a wet scrubber method proved to be very promising for this purpose. In this work, we investigated NOX reduction under EB with the application of NaClO, NaClO2, or NaClO3 as an oxidant in two different scrubber solutions, phosphate buffer (Na2HPO4–KH2PO4)–simulated sea water solution and NaOH–simulated sea water solution. The concentration of buffer in the scrubber solution was 5 mM. The concentration of NaOH in the scrubber solution was 7 mM. Compared with the removal performance of NO for the three different oxidants, the application of NaClO2 gave the best removal efficiency. For the inlet concentration of NO gas set at 1000 ppm and the EB dose set at 10.9 kGy, the application of NaClO2 reaches a maximum of 95.03% NO removal efficiency, while the NaClO oxidant reached a maximum of 49.84% removal efficiency and the NaClO3 oxidant reached a maximum of 54.25% removal efficiency. The results show that the chosen series of oxidants have the potential to be applied in the removal of NOX and SO2 from the off-gases of a diesel engine. For example, they could be used on cargo ships, which generate large amounts of NOX and SO2 from the combustion of heavy oil which contains sulphur and nitrogen.

Influences of planetary boundary layer mixing parameterization on summertime surface ozone concentration and dry deposition over North China

We present a regional modeling study that analyzes how planetary boundary layer (PBL) and surface layer parameterizations influence surface ozone concentrations and dry deposition fluxes over the Beijing-Tianjin-Hebei region in summer (July 2015). We use the Weather Research and Forecasting Model coupled to Chemistry (WRF-Chem) to simulate surface ozone concentration and dry deposition, and examine three PBL schemes: the Yonsei University (YSU), Mellor–Yamada–Janjić (MYJ), and Asymmetric Convective Model version 2 (ACM2) schemes. The model sensitivity to surface layer schemes is also tested by coupling the ACM2 PBL scheme with either the revised MM5-similarity scheme or the Pleim-Xiu surface layer scheme. Key physical and chemical factors for ozone dry deposition parameterization are analyzed to explore the root causes of model discrepancies. We find that all simulations overestimate the summertime daily mean ozone concentrations over North China (42 ppbv in observations vs. 43–50 ppbv in model results for July 2015) that are caused by high biases in daytime ozone and partly compensated by low biases in nighttime ozone. The YSU scheme has the largest overestimate in daily mean ozone concentration, but best reproduces the ozone diurnal cycle. The ACM2 scheme shows the largest underestimates of surface ozone over North China during nighttime, which can be explained by its weakest vertical mixing leading to high NOx concentrations and strong ozone titration near surface. The choices of PBL and surface layer schemes lead to over 20% differences in ozone dry deposition fluxes due to differences in simulated surface ozone concentrations and dry deposition velocities. We find the differences in dry deposition velocity are mainly caused by differences in Monin-Obukhov length during nighttime and surface temperature during daytime. Our study emphasizes the needs to better understand these key PBL and surface factors for reducing the uncertainties in model simulation of surface ozone concentration and dry deposition.

Sea-ice properties and nutrient concentration as drivers of the taxonomic and trophic structure of high-Arctic protist and metazoan communities

In the Arctic Ocean, sea-ice decline will significantly change the structure of biological communities. At the same time, changing nutrient dynamics can have similarly strong and potentially interacting effects. To investigate the response of the taxonomic and trophic structure of planktonic and ice-associated communities to varying sea-ice properties and nutrient concentrations, we analysed four different communities sampled in the Eurasian Basin in summer 2012: (1) protists and (2) metazoans from the under-ice habitat, and (3) protists and (4) metazoans from the epipelagic habitat. The taxonomic composition of protist communities was characterised with 18S meta-barcoding. The taxonomic composition of metazoan communities was determined based on morphology. The analysis of environmental parameters identified (i) a ‘shelf-influenced’ regime with melting sea ice, high-silicate concentrations and low NOx (nitrate + nitrite) concentrations; (ii) a ‘Polar’ regime with low silicate concentrations and low NOx concentrations; and (iii) an ‘Atlantic’ regime with low silicate concentrations and high NOx concentrations. Multivariate analyses of combined bio-environmental datasets showed that taxonomic community structure primarily responded to the variability of sea-ice properties and hydrography across all four communities. Trophic community structure, however, responded significantly to NOx concentrations. In three of the four communities, the most heterotrophic trophic group significantly dominated in the NOx-poor shelf-influenced and Polar regimes compared to the NOx-rich Atlantic regime. The more heterotrophic, NOx-poor regimes were associated with lower productivity and carbon export than the NOx-rich Atlantic regime. For modelling future Arctic ecosystems, it is important to consider that taxonomic diversity can respond to different drivers than trophic diversity.

Effect of ship emissions on O3 in the Yangtze River Delta region of China: Analysis of WRF-Chem modeling

The Yangtze River Delta (YRD) region locates on the eastern coast of China, and it has suffered severe O3 pollutions due to high and mixed emissions of air pollutants. There are 3 different emission sectors for O3 precursors in the region, including anthropogenic VOCS and NOX emissions, ship emissions (mainly NOX), and biogenic emissions from a large forest (biogenic VOCS). This unique emission mixture produces complicated chemical processes in studying the O3 pollutions in the region. This study aims to identify the contribution of the ship emissions to O3 pollutions, as well as the effect of mixing emissions on O3 pollutions in YRD. To identify the individual emission effect, the WRF-Chem model is used in this study. The model generally performs well in simulating meteorological parameters and air pollutants against observations in YRD. Sensitive study suggests that the ship emissions have important effects on the O3 concentrations over ocean and inland, with a maximum increase of 30–50 μg m−3 occurred mainly in the ship track regions. However, the ship emissions have a very complicated effect on the in-land O3 concentrations. In the north of Shanghai, the NOX concentrations are high due to high anthropogenic emissions, and a further increase in NOX emissions from ship results in depressing O3 chemical production. In contrast, in the south of Shanghai, there are high biogenic VOC emissions (mainly isoprene) and low NOx concentrations. As a result, the O3 concentrations are enhanced by 30–50 μg m−3, due to the mixing between ship and forest emissions. This study suggests that ship emissions play important roles in controlling O3 pollutions in YRD. Furthermore, the mixing emissions between ship, anthropogenic, and biogenic emissions in YRD produce a complicated O3 chemical production and need to be carefully considered in controlling strategy of O3 pollution in the region.

Factors controlling dissimilatory nitrate reduction processes in constructed stormwater urban wetlands

Water treatment wetlands are increasingly being used to reduce pollutant loads including nitrogen (N) in urban runoff. Processes such as denitrification (DNF) and anaerobic ammonium oxidation (anammox), which remove N, and dissimilatory nitrate reduction to ammonium (DNRA), which recycles N, play an important role in controlling NOx (NO3− + NO2−) removal versus recycling in wetlands. The relative importance of DNF, anammox and DNRA was investigated in four constructed stormwater urban wetlands in Melbourne, Australia. Rates of DNF and DNRA were variable and did not differ significantly among wetlands. However, rates of DNF and DNRA were significantly different (p < 0.05) in different seasons. The relationship between NOx reduction processes and measured concentrations of water column NOx, chlorophyll a (chl-a), sediment organic carbon (OC), porewater ferrous iron (Fe2+) and sulfide (S2−) and water column temperature were examined using multiple regression analysis (MRA). Anammox was an insignificant pathway (< 0.05% of total nitrate reduction). During winter when average water column temperatures were 12 °C, DNRA was consistently higher than DNF averaging 67 ± 23% of total NOx reduction. The MRA revealed that DNF was positively associated with NOx concentration whereas DNRA was negatively associated with temperature, and porewater Fe2+, and positively associated with chl-a. The ratio between DNF and DNF:(DNF + DNRA) showed a positive correlation with both temperature and NOx concentration in the MRA. At higher temperatures and higher NOx concentrations, DNF increased over DNRA. Overall, this study suggests that at low NOx concentrations, N is recycled internally in these urban stormwater wetlands, but the portion of N removed by DNF increases as NOx concentrations increase.

Quantification of known and unknown terpenoid organosulfates in PM10 using untargeted LC–HRMS/MS: contrasting summertime rural Germany and the North China Plain

Environmental contextSecondary organic aerosols account for a major fraction of atmospheric particulate matter, affecting both climate and human health. Organosulfates, abundant compounds in organic aerosols, are difficult to measure because of the lack of authentic standards. Here we quantify terpene-derived organosulfates in atmospheric particulate matter at a rural site in Germany and at the North China Plain using a combined target/non-target high-resolution mass spectrometry approach. AbstractOrganosulfates (OSs) are a ubiquitous class of compounds in atmospheric aerosol particles. However, a detailed quantification of OSs is commonly hampered because of missing authentic standards and the abundance of unknown OSs. Using a combined targeted and untargeted approach of high-resolution liquid chromatography–Orbitrap mass spectrometry (LC–Orbitrap MS), we quantified for the first time the total concentrations of known and unknown monoterpene (MT) and sesquiterpene (SQT) OSs in summertime PM10 particulate matter from field studies in rural Germany (MEL) and the North China Plain (NCP). At each site, we observed more than 50 MT-OSs, 13 of which were detectable at both sites. For both locations, median concentrations of MT-OSs were in the range of 10 to 40ngm−3, to which the 13 common MT-OSs contributed on average &amp;gt;50%. The main contributor to MT-OSs was C9H16O7S (MT-OS 267) with average mass concentrations of 2.23 and 6.38ngm−3 for MEL and NCP respectively. The concentrations of MT-OSs correlated with the concentrations of MT oxidation products only for MEL. For NCP, the low concentrations of MT oxidation products (i.e. typically &amp;lt;1ngm−3) suggested a suppression of carboxylic acid formation under high concentrations of NOx and particulate sulfate. Furthermore, we observed 17 SQT-OSs for the MEL samples, whereas 40 SQT-OSs were detected in the NCP samples. Only five of these SQT-OSs were detectable at both sites. Correspondingly, the total concentrations of SQT-OSs were larger for NCP than for MEL, which suggested large differences in the particle chemistry. In particular, aerosol acidity was found to be a key factor during SQT-OS formation, and was probably not sufficient in the PM10 from MEL.

Analysis of the impacts of heating emissions on the environment and human health in North China

Cities in North China are facing serious air pollution problems including high concentrations of particles, SO2, and NOx due to heating emissions. The exposure to air pollutants, especially PM2.5, is highly correlated to various adverse health impacts. However, few studies focused on the impact of heating emissions on the environment and health in China. This study aims to address the above-mentioned issues in North China by selecting 62 typical cities with different pollution levels and heating energy consumption as study objects. The heating environment index and PM2.5 concentration were used to show the environmental impact of heating emissions. With respect to the health aspect, eight health endpoints, including the all-cause mortality, cardiovascular mortality, respiratory mortality, lung cancer mortality, chronic bronchitis, cardiovascular diseases, asthma attacks, and acute bronchitis, were evaluated. The results show that the air quality index considering heating emissions is 118.4 [95% confidence interval (CI): 111.5 to 125.2], while that without heating emissions is only 74.3 (95% CI: 68.6 to 79.9). The heating environment index is 0.64 (95% CI: 0.60 to 0.68). The proportion of polluted cities (i.e., with an air quality index larger than 100) is 77.42% considering heating emissions, while it is only 17.74% without considering heating emissions. The average PM2.5 concentration during the heating season in the study region is 75.3 μg/m3 (95% CI: 68.2 to 82.5) and 47.7 μg/m3 (95% CI: 42.6 to 52.7) with and without considering heating emissions, respectively. In terms of the health impact, the total number of premature deaths attributable to heating emissions in the studied cities is 51154, accounting for 0.18‰ of the total population. The analysis shows that heating emissions are the major cause of the health endpoints during the heating season in most cities in North China. This study helps to confirm the quantitative environment and health impacts caused by heating emissions to timely reduce the damage to the human health of residents in North China.

Counteractive effects of regional transport and emission control on the formation of fine particles: a case study during the Hangzhou G20 summit

Abstract. To evaluate the effect of temporary emission control measures on air quality during the 2016 G20 summit held in Hangzhou, China, an intensive field campaign was conducted with a focus on aerosol chemistry and gaseous precursors from 15 August to 12 September 2016. The concentrations of fine particles were reduced during the intense emission control stages, with the reduction of carbonaceous matter being mostly responsible for this observed decrease. This, in turn, was mainly ascribed to the decrease of secondary organic aerosols via the suppression of daytime peak secondary organic carbon (SOC)formation. Although the regional joint control was enacted extending to the Yangtze River Delta region, the effect of long-range transport on the air quality of Hangzhou was ubiquitous. Unexpectedly high NOx concentrations were observed during the control stage, when the strictest restriction on vehicles was implemented, owing to contributions from upstream populous regions such as Jiangsu and Shandong provinces. In addition, the continental outflow traveling over the ocean triggered a short pollution episode on the first day of the G20 summit, resulting in a significant enhancement of the nitrogen/sulfur oxidation rates. In the wake of the summit, all air pollutants evidently rebounded after the various control measures were lifted. Overall, the fraction of secondary inorganic aerosols (SIA; in this case sulfate, nitrate, and ammonium aerosols – SNA) in PM2.5 increased as relative humidity increased; however, the overall concentration of PM2.5 did not increase. Aerosol components that had distinctly different sources and formation mechanisms, e.g., sulfate/nitrate and elemental carbon, exclusively showed strong correlations during the regional/long-range transport episodes. The sulfate, nitrate, and ammonium to elemental carbon (SNA∕EC) ratio, which was used as a proxy for assessing the extent of secondary inorganic aerosol formation, was found to be significantly enhanced under transport conditions from northern China. This study highlighted that emission control strategies were beneficial for curbing particulate pollution, in addition to the fact that regional/long-range transport may offset local emission control effects to some extent.

The prediction of heat efficiency and pollutant emission of non-rated loaded condensing heat exchangers

In order to study the working conditions of condensing heat exchangers under non-rated load conditions, the orthogonal test method was conducted on the condensing gas water heaters by experiment firstly in this paper. Eighty groups of the experimental data about the relationship between the design variables and the object functions were obtained, among them, the design variables include excess air coefficient, flue gas flow, water flow and water flow temperature, and the objective functions include heat exchanger efficiency, NOx and CO emission concentration. The above experimental data were divided into two groups for the training and prediction of neural networks. Here two neural networks of BP artificial neural network (BPNN) and generalized regression neural network (GRNN) will be used to predict the heat efficiency and pollutant emission of condensate heat exchanger at partial load rate. The results show that both BPNN and GRNN structures achieve the required prediction accuracy, and the prediction accuracy of GRNN is higher than that of BPNN. The condensing heat exchanger can achieve higher heat exchanger efficiency and lower concentration of NOx and CO emission at the 90–100% load rate. When the load rate is lower than 30% or higher than 100%, the heat efficiency of the heat exchanger is decreased, and the concentration of pollutant emission is increased rapidly.

NOx instrument intercomparison for laboratory biomass burning source studies and urban ambient measurements in Albuquerque, New Mexico

ABSTRACTUnderstanding nitrogen oxides (NOx = NO + NO2) measurement techniques is important as air-quality standards become more stringent, important sources change, and instrumentation develops. NOx observations are compared in two environments: source testing from the combustion of Southwestern biomass fuels, and urban, ambient NOx. The latter occurred in the urban core of Albuquerque, NM, at an EPA NCORE site during February–March 2017, a relatively clean photochemical environment with ozone (O3) <60 ppb for all but 6 hr. We compare two techniques used to measure NOx in biomass smoke during biomass burning source testing: light absorption at 405 nm and a traditional chemiluminescence monitor. Two additional oxides of nitrogen techniques were added in urban measurements: a cavity attenuated phase shift instrument for direct NO2, and the NOy chemiluminescence instrument (conversion of NOy to NO by molybdenum catalyst). We find agreement similar to laboratory standards for NOx, NO2, and NO comparing all four instruments (R2 > 0.97, slopes between 0.95 and 1.01, intercepts < 2 ppb for 1-hr averages) in the slowly varying ambient setting. Little evidence for significant interferences in NO2 measurements was observed in comparing techniques in late-winter urban Albuquerque. This was also confirmed by negligible NOz contributions as measured with an NOy instrument. For the rapidly varying (1-min) higher NOx concentrations in biomass smoke source testing, larger variability characterized chemiluminescence and absorption instruments. Differences between the two instruments were both positive and negative and occurred for total NOx, NO, and NO2. Nonetheless, integrating the NOx signals over an entire burn experiment and comparing 95 combustion experiments, showed little evidence for large systematic influences of possible interfering species biasing the methods. For concentrations of <2 ppm, a comparison of burn integrated NOx, NO2, and NO yielded slopes of 0.94 to 0.96, R2 of 0.83 to 0.93, and intercepts of 8 to 25 ppb. We attribute the latter, at least in part, to significant noise particularly at low NOx concentrations, resulting from short averaging times during highly dynamic lab burns. Discrepancies between instruments as indicated by the intercepts urge caution with oxides of nitrogen measurements at concentrations <50 ppb for rapidly changing conditions.Implications: Multiple NOx measurement methods were employed to measure NOx concentrations at an EPA NCORE site in Albuquerque, NM, and in smoke produced by the combustion of Southwestern biomass fuels. Agreement shown during intercomparison of these NOx techniques indicated little evidence of significant interfering species biasing the methods in these two environments. Instrument agreement is important to understand for accurately characterizing ambient NOx conditions in a range of environments.

The influence of Animal Fat Methyl Ester (AME) on diesel engine work parameters

This paper presents the analysis of the base energy parameters and composition of exhaust gases for one-cylinder test diesel engine SB 3.1. fuelled by standard diesel fuel (DF) and Animal Fat Methyl Ester (AME). Animal Fat Methyl Ester (AME) is the result of using waste pork fat. A lot of publications analyze the use of fish fat methyl ester (CFME) and chicken fat methyl esters (CFME) but in Polish conditions we have a lot of pork fat waste. All of measurement was carried out on the some engine speed – 1600 rpm (speed of maximum engine torque) and various engine loads. Some of the analysed parameters were read directly from the laboratory measurement systems (e.g. fuel consumption) and the rest of them had been calculated (e.g. total efficiency of engine). Before the engine tests, the basic physical parameters of the used fuels were determined in the fuel laboratory: dynamic viscosity as a function of fuel temperature, distillation curve, combustion heat and calorific value. The calorific value of the used AMF fuel is 37,4 MJ/kg (42,6 MJ/kg for DF). As a result of the AME fuel viscosity analysis, it was found that in the fuel system of the internal combustion engine this fuel should be heated to the temperature 65°C. Hourly AMF fuel consumption is about 9% higher than for standard diesel fuel (DF). The overall efficiency of the engine, taking into account the calorific value of the fuel and the fuel heating energy, is lower by about 7% for the AMF-powered engine than for DF fuelled engine. In the case of an AMF-powered engine, a higher NOx concentration and a lower smoke opacity than for a DF-powered engine are obtained. For more accurate cause and effect analysis, the indicator diagrams and the rate of heat release in the cylinder of the combustion engine fuelled by the tested fuels (AMF and DF) were measured, which includes the second article: The influence of Animals Fat Methyl Ester (AME) on the indicator diagrams and heat release parameters in diesel engine cylinder.

THE RELATIONSHIP BETWEEN LEVELS OF ALDOSTERONE, ESTRADIOL AND SERUM MARKERS OF ENDOTHELIAL DYSFUNCTION IN HYPERTENSIVE WOMEN

Objective: To study the relationship between plasma levels of aldosterone, estradiol and serum markers of endothelial dysfunction (ED) such as stable nitric oxide metabolites NO2-+NO3- (NOx), endothelin-1 (ET-1), homocysteine (HC), von Willebrand factor (vWF) in nondiabetic women with essential hypertension (EH). Design and method: We examined 79 hypertensive, nondiabetic women (mean age 51,4 ± 6,5y, mean EH duration 8,5 ± 7,6y). 28% of the group were smokers, 54% were obese, 76% - with dyslipidemia. Regular menstrual function had 30% of the women, the rest of the group – postmenopausal (median duration of postmenopause was 5,7 ± 3,5y). Circulating NOx levels were studied by spectrophotometry, ET-1, HC, vWF levels – by immunoenzyme assay, aldosterone and estrogen levels - by immunoenzyme assay. Statistical analysis was done using the Statistica 10.0 software. Results: We compared the levels of ED markers in women with a normal (56%), and elevated levels of aldosterone (44%), as well as in women with a normal (62%) and low levels of estradiol (38%). Women with hiperaldosteronemia had higher concentration of NOx (45.3 ± 17.6 and 38.8 ± 16.5 mmol/l, respectively, p < 0.05), E-1 (1.4 ± 1.1 and 0.9 ± 0.8 fmol/l, respectively, p < 0.05) and vWF (1.6 ± 0.8 and 1.3 ± 0.9 mg/dl, respectively, p < 0.05). Aldosterone levels correlated with NOx (r = 0.36, p < 0.05), E-1 (r = 0.3, p < 0.05) and vWF (r = 0.34, p < 0.05) levels. Women with hypoestrogenemia had higher NOx (46.3 ± 16.9 and 37.5 ± 16.0 mmol/l, respectively, p < 0.05), E-1 (1.5 ± 1.1 and 0.8 ± 0.4 fmol/l, respectively, p < 0.05) and vWF (1.6 ± 0.9 and 1.2 ± 0.7 mg/dl, respectively, p < 0.05) levels as well. Estradiol levels correlated with NOx (r = -0.6, p < 0.05) and vWF (r = -0.5, p < 0.05) levels. Conclusions: Our results suggest that women in perimemopausal period demonstrate hormonal disorders with elevation of aldosterone level and decline of estrogen level, which are related to the increase of a number of substances considered as the markers of endothelial dysfunction.

A noble-metal-free SCR-LNT coupled catalytic system used for high-concentration NOx reduction under lean-burn condition

A dual-bed fixed-bed reactor consisting of a selective catalytic reduction (SCR) catalyst and a lean NOx trap (LNT) catalyst is designed and employed for high-concentration NOx removal under lean-burn condition. The lean NOx could be partially reduced over the upstream SCR catalyst (Cu/Al2O3) by C3H6 in the stream, greatly increasing the efficiencies of both NOx storage and NOx reduction over the downstream LNT catalyst (La0.7Sr0.3CoO3). The activity tests for individual catalyst show that the Cu/Al2O3 containing 5 wt.% Cu is the optimal SCR catalyst, which exhibits similar temperature window of activity (300–350 °C) as the LNT catalyst La0.7Sr0.3CoO3. The relative ratio of CuO nanoparticles to surface CuAl2O4 spinel on Cu/Al2O3 is rather important for NO-SCR due to the requirements of appropriate oxidation ability of SCR catalysts. As compared with the single SCR or LNT catalyst, the dual-bed SCR-LNT coupled system shows much lower NOx leak in both lean- and rich-burn periods, especially under the condition of high NOx concentration and high space velocity. Additionally, the NOx to N2O selectivity over this coupled system is as low as ∼4%, showing obvious advantage over conventional noble metals-based SCR and LNT catalysts.

Ozone impacts of gas–aerosol uptake in global chemistry transport models

Abstract. The impact of six heterogeneous gas–aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3, and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density (Sa) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3, and HO2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NOx concentrations and high Sa in the same region. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with the biggest impacts on O3 in springtime when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated. Our results are loosely consistent with results from earlier studies, although the magnitude of changes induced by N2O5 reaction is at the low end of estimates, which seems to fit a trend, whereby the more recent the study the lower the impacts of these reactions.

A hybrid plasma-chemical system for high-NOx flue gas treatment

The reduction of high concentrations of NOx and SO2 from simulated flue gas has been studied. Our aim was to optimise energy consumption for NOx and SO2 removal from off-gases from a diesel generator using heavy fuel oil. A hybrid process: electron beam (EB) plasma and wet scrubber has been applied. A much higher efficiency of NOx and SO2 removal was achieved in comparison to dry, ammonia free, electron beam flue gas treatment (EBFGT). A recorded removal from a concentration of 1500ppm NOx reached 49% at a low dose of 6.5kGy, while only 2% NOx was removed at the same dose if EB only was applied. For SO2, removal efficiency at a dose of 6.5kGy increased from 15% (EB only) to 84% when sea water was used as a wet scrubber agent for 700ppm SO2. The results of this study indicate that EB combined with wet scrubber is a very promising technology to be applied for removal of high concentrations of NOx and SO2 emitted from diesel engines operated e.g. on cargo ships, which are the main sources of SO2 and NOx pollution along their navigation routes.

NOx promotion of SO2 conversion to sulfate: An important mechanism for the occurrence of heavy haze during winter in Beijing.

In this study, concentrations of NOx, SO2, O3 and fine particles (PM2.5) were measured at three monitoring stations in Beijing during 2015. For extreme haze episodes during 25 Nov. - 3 Dec. 2015, observation data confirmed that high concentrations of NOx promoted the conversion of SO2 to sulfate. Annual data confirmed that this is an important mechanism for the occurrence of heavy haze during winter in Beijing. Furthermore, in situ perturbation experiments in a potential aerosol mass (PAM) reactor were carried out at Shengtaizhongxin (STZX) station during both clean and polluted days. The concentrations of SO42-, NH4+, NO3- and organic aerosol were positively related to the concentration of added NO2. These results provide definitive evidence that NO2 can promote the conversion of SO2 to sulfate. At the same time, we found that NO2 can promote the formation of NH4+ and organic compounds in the aerosols. Our results illustrate that strengthened controls of nitrogen oxides is a key step in reducing the fine particles level in China.