Nocturnal Concentrations Research Articles

A mixed layer height parameterization in a 3-D chemical transport model: Implications for gas and aerosol simulations

Vertical mixing within the planetary boundary layer (PBL) is crucial for determining surface-level pollutant concentrations. However, standard PBL schemes in chemical transport models (CTMs) often fail to adequately define the upper bounds of vertical mixing, particularly at night. This limitation frequently results in overestimated nocturnal concentrations of pollutants near the surface. To address this issue, we propose a parameterization of mixed layer height (MLH) derived from the Yonsei University (YSU) PBL scheme and thoroughly evaluate it by comparing simulations with various observations. We utilized the Weather Research and Forecasting model coupled with GEOS-Chem (WRF-GC) to simulate gas and aerosol distributions over South Korea during the Satellite Integrated Joint Monitoring of Air Quality (SIJAQ) campaign in 2021. The WRF-GC simulations incorporating the MLH parameterization improved the excessive titration of O3 and the overproduction of HNO3 and NO3− in the model. Consequently, the model performances in gaseous and aerosol simulations showed a better agreement with observations, with changes in normalized mean biases (NMBs) of NOX (from 50 % to −27 %), O3 (from −49 % to −28 %), NO3− (from 126 % to 91 %), NH4+ (from 113 % to 85 %), BC (from 322 % to 135 %), and PM2.5 (from 58 % to 28 %).

Respiratory and Photosynthetic Responses of Antarctic Vascular Plants Are Differentially Affected by CO2 Enrichment and Nocturnal Warming

Projected rises in atmospheric CO2 concentration and minimum night-time temperatures may have important effects on plant carbon metabolism altering the carbon balance of the only two vascular plant species in the Antarctic Peninsula. We assessed the effect of nocturnal warming (8/5 °C vs. 8/8 °C day/night) and CO2 concentrations (400 ppm and 750 ppm) on gas exchange, non-structural carbohydrates, two respiratory-related enzymes, and mitochondrial size and number in two species of vascular plants. In Colobanthus quitensis, light-saturated photosynthesis measured at 400 ppm was reduced when plants were grown in the elevated CO2 or in the nocturnal warming treatments. Growth in elevated CO2 reduced stomatal conductance but nocturnal warming did not. The short-term sensitivity of respiration, relative protein abundance, and mitochondrial traits were not responsive to either treatment in this species. Moreover, some acclimation to nocturnal warming at ambient CO2 was observed. Altogether, these responses in C. quitensis led to an increase in the respiration-assimilation ratio in plants grown in elevated CO2. The response of Deschampsia antarctica to the experimental treatments was quite distinct. Photosynthesis was not affected by either treatment; however, respiration acclimated to temperature in the elevated CO2 treatment. The observed short-term changes in thermal sensitivity indicate type I acclimation of respiration. Growth in elevated CO2 and nocturnal warming resulted in a reduction in mitochondrial numbers and an increase in mitochondrial size in D. antarctica. Overall, our results suggest that with climate change D. antarctica could be more successful than C. quitensis, due to its ability to make metabolic adjustments to maintain its carbon balance.

PINEAL GLAND AND PREECLAMPSIA – A MODERN VIEW OF THE PROBLEM (LITERATURE REVIEW)

Preeclampsia is a complex pathological process which development signifi cantly depends on a decrease in melatonin levels of pregnant women as a result of the pineal gland and placenta dysfunction. The most important hormone of the pineal gland is melatonin, which is a derivative of tryptophan – an essential amino acid. Melatonin is a powerful natural antioxidant. When it’s levels are decreased, there is a risk of preeclampsia progression as a pathological condition of pregnant women, accompanied by high blood pressure, systemic multiple- organ failure and even cerebral edema and convulsions.Thus, although preeclampsia is considered a disease of the mother, it should rather be considered as a pathological condition of the placenta that aff ects both mother’s and fetus health. As the key factor of placental diorders is an oxidative stress, many researchers consider melatonin to be a potentially useful option for treating preeclampsia. It is noted that pregnant women with preeclampsia have a decrease in nocturnal concentrations of melatonin in comparison with healthy pregnant women that may indicate about pineal gland dysfunction in preeclampsia. Therefore, the normalization of melatonin levels may be a promising direction in the treatment of pregnant women with preeclampsia.

ОЦЕНКА НОЧНЫХ ЭМИССИЙ ПАРНИКОВЫХ ГАЗОВ В ГОРОДЕ ЕКАТЕРИНБУРГ ЗА 2018-2019 ГГ

Surface fluxes of carbon gases in Yekaterinburg during 2018-2019 are estimated, their values are 82.77 ± 28.31, 6120 ± 2132, 17.97 ± 6.6 t/(km2 year) for СО, СО2, and СН4, respectively. Continuous measurements of concentrations in the atmospheric surface layer were conducted at the Institute of Industrial Ecology (Ural Branch, Russian Academy of Sciences) in Yekaterinburg using the Picarro G2401 gas analyzer. The regions with increasing nocturnal concentrations of carbon gases in calm conditions were detected during the surface fluxes estimation: wind speed was 0-1 m/s. Further calculation of surface fluxes for the selected time intervals was based on the measured concentrations and some meteorological parameters (the height of the atmospheric boundary layer, temperature, etc.). The results of the present study are comparable with the results of the studies that used a similar method. A surface fluxes growth is observed as the population size increases, while a dependence on the population density is not revealed. The largest contribution to the total uncertainty is made by the height of the atmospheric boundary layer.

Winter ClNO<sub>2</sub> formation in the region of fresh anthropogenic emissions: seasonal variability and insights into daytime peaks in northern China

Abstract. Nitryl chloride (ClNO2) is an important chlorine reservoir in the atmosphere that affects the oxidation of volatile organic compounds (VOCs) and the production of ROx radicals and ozone (O3). This study presents measurements of ClNO2 and related compounds at urban, polluted rural, and polluted lower tropospheric (mountaintop) sites in the winter of 2017–2018 over the North China Plain (NCP). The nocturnal concentrations of ClNO2 were lower at the urban and polluted rural sites but higher at the polluted lower tropospheric site. The winter concentrations of ClNO2 were generally lower than the summer concentrations that were previously observed at these sites, which was due to the lower nitrate radical (NO3) production rate (P(NO3)) and the smaller N2O5 uptake coefficients (γ(N2O5)) in winter, despite the higher ratios of dinitrogen pentoxide (N2O5) to NO3 in winter. Significant daytime peaks of ClNO2 were observed at all the sites during the winter campaigns, with ClNO2 mixing ratios of up to 1.3 ppbv. Vertical transport of ClNO2 from the residual layers and prolonged photochemical lifetime of ClNO2 in winter may explain the elevated daytime concentrations. The daytime-averaged chlorine radical (Cl) production rates (P(Cl)) from the daytime ClNO2 were 0.17, 0.11, and 0.12 ppbv h−1 at the polluted rural, urban, and polluted lower tropospheric sites, respectively, which were approximately 3–4 times higher than the campaign-averaged conditions. Box model calculations showed that the Cl atoms liberated during the daytime peaks of ClNO2 increased the ROx levels by up to 27 %–37 % and increased the daily O3 productions by up to 13 %–18 %. Our results provide new insights into the ClNO2 processes in the lower troposphere impacted by fresh and intense anthropogenic emissions and reveal that ClNO2 can be an important daytime source of Cl radicals under certain conditions in winter.

Efficacy and safety of electroacupuncture combined with Suanzaoren decoction for insomnia following stroke: study protocol for a randomized controlled trial

BackgroundInsomnia is a common but frequently overlooked sleep disorder after stroke, and there are limited effective therapies for insomnia following stroke. Traditional Chinese medicine (TCM), including acupuncture and the Chinese herbal medication (CHM) Suanzaoren decoction (SZRD), has been reported as an alternative option for insomnia relief after stroke in China for thousands of years. Here, this study aims to investigate the efficacy and safety of electroacupuncture (EA) in combination with SZRD in the treatment of insomnia following stroke.MethodsA total of 240 patients with post-stroke insomnia will be included and randomized into four groups: the EA group, SZRD group, EA & SZRD group, and sham group. The same acupoints (GV20, GV24, HT7, and SP6) will be used in the EA group, EA & SZRD group, and sham group, and these patients will receive the EA treatment or sham manipulation every other day for 4 consecutive weeks. SZRD treatments will be given to participants in the SZRD group and EA & SZRD group twice a day for 4 consecutive weeks. The primary outcome measures include Pittsburgh Sleep Quality Index scores and polysomnography. Secondary outcome measures include the Insomnia Severity Index, the National Institutes of Health Stroke Scale, the Hospital Anxiety and Depression Scale, brain magnetic resonance imaging, functional magnetic resonance imaging, and nocturnal melatonin concentrations. The primary and secondary outcomes will be assessed at baseline (before treatment), during the 2nd and 4th weeks of the intervention, and at the 8th and 12th weeks of follow-up. Safety assessments will be evaluated at baseline and during the 4th week of the intervention.DiscussionThis study will contribute to assessing whether the combination of these two therapies is more beneficial for post-stroke insomnia than their independent use, and the results of this clinical trial will improve our understanding of the possible mechanisms underlying the effects of combination therapies.Trial registrationChinese Clinical Trials Register ChiCTR2000031413. Registered on March 30, 2020

Improved Nocturnal Glycaemia and Reduced Insulin Use Following Clinical Exercise Trial Participation in Individuals With Type 1 Diabetes.

Aim: To explore the influence of clinical exercise trial participation on glycaemia and insulin therapy use in adults with type 1 diabetes (T1D).Research Design and Methods: This study involved a secondary analysis of data collected from 16 individuals with T1D who completed a randomized clinical trial consisting of 23-h in-patient phases with a 45-min evening bout of moderate intensity continuous exercise. Participants were switched from their usual basal-bolus therapy to ultra-long acting insulin degludec and rapid-acting insulin aspart as well as provided with unblinded interstitial flash-glucose monitoring systems. To assess the impact of clinical trial participation, weekly data obtained at the screening visit (pre-study involvement) were compared against those collated on the last experimental visit (post-study involvement). Interstitial glucose [iG] data were split into distinct glycaemic ranges and stratified into day (06:00–23:59) and night (00:00–05:59) time periods. A p-value of ≤ 0.05 was accepted for significance.Results: Following study completion, there were significant decreases in both the mean nocturnal iG concentration (Δ-0.9 ± 4.5 mmol.L−1, p < 0.001) and the time spent in severe hyperglycaemia (Δ-7.2 ± 9.8%, p = 0.028) during the night-time period. The total daily (Δ-7.3 ± 8.4 IU, p = 0.003) and basal only (Δ-2.3 ± 3.8 IU, p = 0.033) insulin dose requirements were reduced over the course of study involvement.Conclusions: Participation in clinical research may foster improved nocturnal glycaemia and reduced insulin therapy use in people with T1D. Recognition of these outcomes may help encourage volunteers to partake in clinical research opportunities for improved diabetes-related health outcomes.Clinical Trial Registration: DRKS.de; DRKS00013509.

The comparison of nocturnal and fasting ghrelin concentration in children with growth hormone deficiency and with idiopathic short stature

The comparison of nocturnal and fasting ghrelin concentration in children with growth hormone deficiency and with idiopathic short stature

Sources and health risks of PM2.5-bound polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in a North China rural area

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are typical persistent organic pollutants (POPs), which have high toxicity, bioaccumulation and long-distance transfer capability. Daily variation, sources of PCBs and OCPs in PM2.5 are rarely explored in polluted rural area. Here, the sources and health risks of the PCBs and OCPs were evaluated for 48 PM2.5 samples collected in winter 2017 in Wangdu, a heavy polluted rural area in the North China Plain. The average diurnal and nocturnal concentrations of Σ18PCBs and Σ15OCPs were 1.74-24.37 and 1.77-100.49, 11.67-408.81 and 16.89-865.60 pg/m3, respectively. Hexa-CBs and penta-CBs accounted for higher proportions (29.0% and 33.6%) of clean and polluted samples, respectively. Hexachlorobenzene (HCB) was the dominant contributor to OCPs with an average concentration of 116.17 pg/m3. Hexachlorocyclohexane (ΣHCHs) and dichlorodiphenyltrichloroethane (ΣDDTs) were the other two main classes in OCPs with the average concentrations of 4.33 and 15.89 pg/m3, respectively. β-HCH and p,p’-DDE were the main degradation products of HCHs and DDTs, respectively. The principal component analysis and characteristic ratio method indicated both waste incineration and industrial activities were the main sources of PCBs, contributing 76.8% and 12.7%, respectively. The loadings of OCPs were attributed to their application characteristics and the characteristic ratio method reflected a current or past use of OCPs. Health risk assessment showed that the respiratory exposure quantity of doxin-like PCBs (DL-PCBs) and the lifetime cancer risk from airborne OCPs exposure was negligible, while the other exposure modes may pose a risk to human bodies.

Sympathetic Hyperactivity and Sleep Disorders in Individuals With Type 2 Diabetes.

Introduction: Many studies on the impact of type 2 diabetes mellitus (T2DM) on sleep breathing have shown a higher prevalence and severity of sleep apnea-hypopnea syndrome (SAHS) in those with T2DM. Moreover, an increased activity of the sympathetic nervous system has been described in both pathologies. This cross-sectional study aimed to assess sympathetic activity in patients with T2DM, and to investigate the relationship between sympathetic activity and polysomnographic parameters.Materials and Methods: Thirty-six patients with T2DM without known clinical macrovascular nor pulmonary disease and 11 controls underwent respiratory polygraphy, and their cardiac variability and 24-h urine total metanephrines were measured.Results: SAHS was highly prevalent with a mean apnea-hypopnea index (AHI) in the range of moderate SAHS. In patients with T2DM, the nocturnal concentration of total metanephrines in urine were higher than diurnal levels [247.0 (120.0–1375.0) vs. 210.0 (92.0–670.0), p = 0.039]. The nocturnal total metanephrine concentration was positively and significantly associatedwith the percentage of sleeping time spent with oxygen saturation <90%(CT90). In the entire population and in subjects with T2DM, the multivariate regression analysis showed a direct interaction between the nocturnal concentration of urine metanephrines and the CT90.Conclusion: These findings suggest that the increase in sympathetic activity previously described in patients with T2DM could be mediated through nocturnal breathing disturbances. The diagnosis and treatment of SAHS may influence sympathetic activity disorders and may contribute to an improvement in T2DM and cardiovascular risk.

Estudo da associação entre óxidos de nitrogênio e concentração de ozônio com parâmetros meteorológicos

O presente estudo investiga as relações das medidas tanto da concentração de ozônio (O3) como de óxidos de nitrogênio (NOx = NO + NO2) em função das condições meteorológicas para a atmosfera de Campo Grande, MS, no período compreendido de janeiro a dezembro de 2015. Variações diurnas e sazonais de poluentes gasosos foram investigadas e comparadas usando os resultados da análise de séries temporais. Os ciclos diurnos de O3 e de NOx se relacionam inversamente com o O3 superficial, que apresenta picos ao meio dia, e menores concentrações noturnas. Os resultados mostram que as concentrações máximas de O3 e oxidantes (Ox = O3 + NOx) em Campo Grande geralmente aparecem no início da tarde, por volta das 15:00 horas. A variação diária das concentrações de NO mostra um ciclo muito claro com dois picos, um aparecendo por volta das 07:00 e outro às 11:00 horas. No nível mais baixo, o NO2 é o principal componente do NOx, enquanto o NO domina a maior taxa de mistura. Fortes correlações positivas foram observadas entre o O3 com a temperatura e a radiação solar, e com forte correlação negativa com a umidade relativa do ar, durante o período estudado.

Seasonal and geographical variability of nitryl chloride and its precursors in Northern Europe

Measurements of nitryl chloride (ClNO2) and its precursors (O3, NO2, particulate chloride) were made in 2014–2016 at three contrasting locations in the United Kingdom: Leicester, Penlee Point and Weybourne. ClNO2 was observed at all sites and in every season, with the highest concentrations between 00:00 and 04:00 GMT. The median nocturnal concentration of ClNO2 ranged between the detection limit (4.2 ppt) and 139 ppt. A clear seasonal cycle, with maxima in spring and winter, and significant differences between locations in the same season were observed. The main source of particulate chloride was sea salt aerosol (including at Leicester, ∼200 km from the coast). In general, ClNO2 levels were controlled by the concentrations of O3 and NO2, rather than by the uptake and reaction of N2O5 with particulate chloride. Under these conditions, the seasonality and geographical distribution of ClNO2 can be explained in terms of O3‐limited and NO2‐limited regimes affecting the formation of the N2O5 precursor. A global version of the GEOS‐Chem model at medium resolution (2° × 2.5°) was not able to fully capture the observed seasonality of ClNO2, mostly because the model overestimated the concentrations of the precursors, particularly of nocturnal O3. A higher‐resolution (0.25° × 0.3125°) version of GEOS‐Chem showed better agreement with the observations, although it still overestimated ClNO2 concentrations during summer.

Increased nocturnal CO2 concentration during breeze circulation events in a tropical reservoir

The Balbina reservoir (59°28'50'' W, 1°53'25'' S), located near the city of Manaus, AM in central Amazonia, is the second largest hydroelectric reservoir in the Amazon basin. Carbon dioxide concentration measurements were performed at high frequency (10 Hz) at this reservoir with an IRGA Model LiCOR 7500A and meteorological variables were measured with a floating platform with sensors 2 meters above the surface of the lake. Maximum and minimum CO2 concentrations were observed during the night, related to forest breeze enriched with CO2 and the respiration or photosynthetic activity of the lake. Due to the dimensions of the lake, both land and lake breezes control the concentration of CO2. CO2 showed a strong correlation with the meteorological variables, temperature (- 0.76) and relative humidity (0.71). However, only the wind direction showed a statistically significant effect at 5% in the cross-correlation. Our results corroborate other studies in this lake and other Amazonian reservoirs.

Continuous Glucose Monitoring in Female NOD Mice Reveals Daily Rhythms and a Negative Correlation With Body Temperature.

Previous studies with continuous glucose monitoring in mice have been limited to several days or weeks, with the mouse's physical attachment to the equipment affecting behavior and measurements. In the current study, we measured blood glucose and body temperature at 10-second intervals for 12 weeks in a cohort of NOD/ShiLtJ female mice using wireless telemetry. This allowed us to obtain a high-resolution profile of the circadian rhythm of these two parameters and the onset of hyperglycemic development in real time. The most striking observations were the elevated nocturnal concentrations of glucose into the diabetic range days before elevations in diurnal glucose (when glucose concentrations are historically measured) and the strong, negative correlation between elevated blood glucose concentrations and body temperature with a steady decline of the body temperature with diabetes development. Taken together, this technological advancement provides improved resolution in the study of the disease trajectory of diabetes in mouse models, including relevant translatability to the current technologies of continuous glucose monitoring now regularly used in patients.

Observations of N2O5 and ClNO2 at a polluted urban surface site in North China: High N2O5 uptake coefficients and low ClNO2 product yields

Dinitrogen pentoxide (N2O5) and its heterogeneous uptake product, nitryl chloride (ClNO2), play important roles in the nocturnal boundary layer chemistry. To understand the abundances and chemistry of N2O5 and ClNO2 in the polluted urban atmosphere in North China, field measurements were conducted by deploying a chemical ionization mass spectrometer in urban Ji'nan in September 2014. The observed surface N2O5 concentrations were relatively low, with an average nocturnal value of 22 pptv, although the source of NO3 was rather strong, i.e., the NO2 and O3 were at very high levels. The N2O5 concentration peaked in the early evening, which was associated with thermal power plant plumes and residual O3. Nocturnal N2O5 was lost very rapidly, mainly through heterogeneous reactions on aerosol surfaces. The estimated N2O5 uptake coefficient was in the range of 0.042–0.092, among the highest values obtained from ground based field measurements. The fast heterogeneous reaction of N2O5 on high loadings of aerosols generated relatively high levels of ClNO2, with an average nocturnal concentration of 132 pptv. Despite the rich chloride content in aerosols, the ClNO2 product yield was low, 0.014 and 0.082 in two nighttime cases, much lower than the calculated values from the experiment-derived parameterization. The suppressed chlorine activation in polluted urban atmospheres was possibly associated with the reduced hygroscopicity, solubility, and activity of chloride in complex ambient aerosols.

Relationship of nocturnal concentrations of melatonin, gamma-aminobutyric acid and total antioxidants in peripheral blood with insomnia after stroke: study protocol for a prospective non-randomized controlled trial.

Melatonin and gamma-aminobutyric acid (GABA) have been shown to regulate sleep. The nocturnal concentrations of melatonin, GABA and total antioxidants may relate to insomnia in stroke patients. In this prospective single-center non-randomized controlled clinical trial performed in the China Rehabilitation Research Center, we analyzed the relationship of nocturnal concentrations of melatonin, GABA and total antioxidants with insomnia after stroke. Patients during rehabilitation of stroke were recruited and assigned to the insomnia group or non-insomnia group. Simultaneously, persons without stroke or insomnia served as normal controls. Each group contained 25 cases. The primary outcome was nocturnal concentrations of melatonin, GABA and total antioxidants in peripheral blood. The secondary outcomes were Pittsburgh Sleep Quality Index, Insomnia Severity Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Morningness-Eveningness Questionnaire (Chinese version), and National Institute of Health Stroke Scale. The relationship of nocturnal concentrations of melatonin, GABA and total antioxidants with insomnia after stroke was analyzed and showed that they were lower in the insomnia group than in the non-insomnia group. The severity of stroke was higher in the insomnia group than in the non-insomnia group. Correlation analysis demonstrated that the nocturnal concentrations of melatonin and GABA were associated with insomnia after stroke. This trial was registered at ClinicalTrials.gov, identifier: NCT03202121.

Day-night variability of water-soluble ions in PM10 samples collected at a traffic site in southeastern Spain

The present work reports diurnal and nocturnal concentrations of water-soluble ions associated to PM10 samples collected during the warm and cold seasons in the urban center of Elche (Southeastern Spain). Statistical differences between daytime and nighttime levels of PM10 were only observed during winter. The lower concentrations during the night were most likely the result of a reduction in traffic-induced road dust resuspension, since nocturnal concentrations of calcium also exhibited a significant decrease compared to daytime levels. During the warm season, nitrate was the only component that showed a statistically significant increase from day to night. The lower nocturnal temperatures that prevent the thermal decomposition of ammonium nitrate and the formation of nitric acid favored by the higher relative humidity at night are the most probable reasons for this variation. The close relationship between nitrate formation and relative humidity during nighttime was supported by the results of the correlation analysis. The reaction of sulfuric and nitric acids with CaCO3 occurred to a greater extent during daytime in summer.

Variation of Size Distribution and the Influencing Factors of Aerosol in Northern Suburbs of Nanjing

The size distribution of particulate was analyzed by the FA-3 9 stage sampler in Northern-suburb of Nanjing from January to November in 2014. First, the monitoring result from FA-3 was compared with the results of the same period obtained from a medium flow size grading sampler (KC-120H) and online monitoring instrument of the Environmental Protection Agency. The data correlation coefficients were all greater than 0.95. The fine particle concentration from FA-3 was lower by 13.9% and 16.6%, while PM10 concentration was higher by 15.2% and 13.3% respectively. However, the deviations were in the acceptable range of atmospheric sampling which could indicate the accurate classification and sampling of particulate for FA-3. Particulate pollution in Northern-suburb Nanjing was serous in which the annual average concentrations of PM1.1, PM2.1 and PM10 were(65.6±37.6), (91.0±54.7) and (168.0±87.0) μg·m-3 respectively; fine particles dominated and most of them had a diameter of less than 1.1 μm. Particle size distribution was bimodal with peaks at 0.43-0.65 and 9-10 μm; the median diameter was 1.83 μm which was in the accumulation mode. In winter, the concentration of fine particle size was higher and in spring the coarse particle size was higher; in summer, the fine particle size concentration was not significantly reduced but coarse particle size was obviously lower than those in other seasons. The differences of particle size distribution in day and at night were very small in coarse segment and in fine segment, the nocturnal concentrations were mostly higher than diurnal concentrations. The precipitation had cleaning effect for each size range of particulate except in summer and the effect was more distinct in fine particle size. In haze days, with the aggravation of haze level, the particle concentration in the diameter range of 0.43-2.1 μm increased gradually while in this segment the particle concentration was significantly negatively correlated with visibility. Using relative humidity of 70% as the demarcation, the particle size distribution changed significantly:when humidity was greater than 70%, mass concentration of particle with a diameter of less than 0.43 μm reduced significantly but that with diameter range of 0.43-2.1 μm increased obviously which should be related to the particle hygroscopic growth. The air mass sources could be divided into four categories in northern-suburb of Nanjing. Air mass from the northwest with rapid transport velocity was the cleanest in which the fine particle size concentration was significantly lower than those in other directions; the air mass from local and surrounding was the most severely polluted with high concentrations in both fine and coarse segment, its transmission distance was short and wind speed was small which contributed greatly to air pollution of Nanjing with probability of occurrence of pollution reaching 73.9%.

Size-resolved aerosol composition at an urban and a rural site in the Po Valley in summertime: implications for secondary aerosol formation

Abstract. The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles.

Plasma soluble erythropoietin receptor is decreased during sleep in Andean highlanders with Chronic Mountain Sickness.

Excessive erythrocytosis (EE) is the main sign of Chronic Mountain Sickness (CMS), a highly prevalent syndrome in Andean highlanders. Low pulse O2 saturation (SpO2) during sleep and serum androgens have been suggested to contribute to EE in CMS patients. However, whether these factors have a significant impact on the erythropoietin (Epo) system leading to EE is still unclear. We have recently shown that morning soluble Epo receptor (sEpoR), an endogenous Epo antagonist, is decreased in CMS patients suggesting increased Epo availability (increased Epo/sEpoR). The present study aimed to characterize the nocturnal concentration profile of sEpoR and Epo and their relationship with SpO2, Hct, and serum testosterone in healthy highlanders (HH) and CMS patients. Epo and sEpoR concentrations were evaluated every 4 h (6 PM to 6 AM) and nighttime SpO2 was continuously monitored (10 PM to 6 AM) in 39 male participants (CMS, n = 23; HH, n = 16) aged 21-65 yr from Cerro de Pasco, Peru (4,340 m). CMS patients showed higher serum Epo concentrations throughout the night and lower sEpoR from 10 PM to 6 AM. Consequently, Epo/sEpoR was significantly higher in the CMS group at every time point. Mean sleep-time SpO2 was lower in CMS patients compared with HH, while the percentage of sleep time spent with SpO2 < 80% was higher. Multiple-regression analysis showed mean sleep-time SpO2 and Epo/sEpoR as significant predictors of hematocrit corrected for potential confounders (age, body mass index, and testosterone). Testosterone levels were associated neither with Hct nor with erythropoietic factors. In conclusion, our results show sustained erythropoietic stimulus driven by the Epo system in CMS patients, further enhanced by a continuous exposure to accentuated nocturnal hypoxemia.