Aerosol mass and the absorbing fraction are important variables, needed to constrain the role of atmospheric particles in the Earth radiation budget, both directly and indirectly through CCN ...activation. In particular, their monitoring in remote areas and mountain sites is essential for determining source regions, elucidating the mechanisms of long range transport of anthropogenic pollutants, and validating regional and global models. Since March 2006, aerosol mass and black carbon concentration have been monitored at the Nepal Climate Observatory-Pyramid, a permanent high-altitude research station located in the Khumbu valley at 5079 m a.s.l. below Mt. Everest. The first two-year averages of PM1 and PM1−10 mass were 1.94 μg m−3 and 1.88 μg m−3, with standard deviations of 3.90 μg m−3 and 4.45 μg m−3, respectively, while the black carbon concentration average is 160.5 ng m−3, with a standard deviation of 296.1 ng m−3. Both aerosol mass and black carbon show well defined annual cycles, with a maximum during the pre-monsoon season and a minimum during the monsoon. They also display a typical diurnal cycle during all the seasons, with the lowest particle concentration recorded during the night, and a considerable increase during the afternoon, revealing the major role played by thermal winds in influencing the behaviour of atmospheric compounds over the high Himalayas. The aerosol concentration is subject to high variability: in fact, as well as frequent "background conditions" (55% of the time) when BC concentrations are mainly below 100 ng m−3, concentrations up to 5 μg m−3 are reached during some episodes (a few days every year) in the pre-monsoon seasons. The variability of PM and BC is the result of both short-term changes due to thermal wind development in the valley, and long-range transport/synoptic circulation. At NCO-P, higher concentrations of PM1 and BC are mostly associated with regional circulation and westerly air masses from the Middle East, while the strongest contributions of mineral dust arrive from the Middle East and regional circulation, with a special contribution from North Africa and South-West Arabian Peninsula in post-monsoon and winter season.
Disruption or loss of oligodendrocytes (OLs) and myelin has devastating effects on CNS function and integrity, which occur in diverse neurological disorders, including Multiple Sclerosis (MS), ...Alzheimer’s disease and neuropsychiatric disorders. Hence, there is a need to develop new therapies that promote oligodendrocyte regeneration and myelin repair. A promising approach is drug repurposing, but most agents have potentially contrasting biological actions depending on the cellular context and their dose-dependent effects on intracellular pathways. Here, we have used a combined systems biology and neurobiological approach to identify compounds that exert positive and negative effects on oligodendroglia, depending on concentration. Notably, next generation pharmacogenomic analysis identified the PI3K/Akt modulator LY294002 as the most highly ranked small molecule with both pro- and anti-oligodendroglial concentration-dependent effects. We validated these in silico findings using multidisciplinary approaches to reveal a profoundly bipartite effect of LY294002 on the generation of OPCs and their differentiation into myelinating oligodendrocytes in both postnatal and adult contexts. Finally, we employed transcriptional profiling and signalling pathway activity assays to determine cell-specific mechanisms of action of LY294002 on oligodendrocytes and resolve optimal in vivo conditions required to promote myelin repair. These results demonstrate the power of multidisciplinary strategies in determining the therapeutic potential of small molecules in neurodegenerative disorders.
Display omitted
The Kathmandu Valley in south Asia is considered as one of the global "hot spots" in terms of urban air pollution. It is facing severe air quality problems as a result of rapid urbanization and land ...use change, socioeconomic transformation, and high population growth. In this paper, we present the first full year (February 2013-January 2014) analysis of simultaneous measurements of two short-lived climate forcers/pollutants (SLCF/P), i.e., ozone (O3) and equivalent black carbon (hereinafter noted as BC) and aerosol number concentration at Paknajol, in the city center of Kathmandu. The diurnal behavior of equivalent BC and aerosol number concentration indicated that local pollution sources represent the major contributions to air pollution in this city. In addition to photochemistry, the planetary boundary layer (PBL) and wind play important roles in determining O3 variability, as suggested by the analysis of seasonal changes of the diurnal cycles and the correlation with meteorological parameters and aerosol properties. Especially during pre-monsoon, high values of O3 were found during the afternoon/evening. This could be related to mixing and entrainment processes between upper residual layers and the PBL. The high O3 concentrations, in particular during pre-monsoon, appeared well related to the impact of major open vegetation fires occurring at the regional scale. On a synoptic-scale perspective, westerly and regional atmospheric circulations appeared to be especially conducive for the occurrence of the high BC and O3 values. The very high values of SLCF/P, detected during the whole measurement period, indicated persisting adverse air quality conditions, dangerous for the health of over 3 million residents of the Kathmandu Valley, and the environment. Consequently, all of this information may be useful for implementing control measures to mitigate the occurrence of acute pollution levels in the Kathmandu Valley and surrounding area.
Methane (CH4) is an important climate forcer, contributing about 17% of the total radiative forcing by long living greenhouse gases. The Po basin is one of the most polluted and densely populated ...areas in Europe representing an important source region for CH4.
The aim of this work was to test an inter-species correlation approach to derive estimates of anthropogenic CH4 emissions for the period 2015–2019 from the Po basin by combining CO bottom-up inventory data and continuous CH4 and CO observations from a mountain site in the northern Italy. The tested methodology suggested lower emissions in respect to EDGAR (−17%) and the Italian National Inventory (−40%) for the Po basin. However, despite the two bottom-up inventories, the emissions derived from the atmospheric observations reported an increasing tendency from 2015 to 2019 for the CH4 emissions. A sensitivity study revealed that using different subsets of the atmospheric observations implied a difference of 26% in the CH4 emission estimates. The highest agreement with two bottom-up CH4 inventories (EDGAR and the Italian national inventory) were obtained when atmospheric data were strictly selected for periods representative of air mass transport from the Po basin.
Our study identified various challenges when using this methodology as a benchmark to verify bottom-up CH4 inventories. Issues could be attributed to the annual aggregation of the proxies used to derive the emission amounts, to the CO bottom-up inventory used as input information and to the relatively high sensitivity of the results to the different subsets of the atmospheric observations. However, the use of different bottom-up inventories as input data for CO emissions can potentially provide information that should be carefully considered for the purpose of integrating CH4 bottom-up inventories.
•We tested and used an inter-species correlation approach to calculate anthropogenic CH4 emissions from the Po basin.•Atmospheric observations from a mountain site were used.•Differences with bottom-up inventories were pointed out for 4 investigated years.•An accurate selection of the atmospheric data is pivotal for getting reliable information.•Yearly aggregation of data and input CO emissions led to further uncertainties.
This work investigates the variability of ozone (O3), carbon monoxide (CO) and equivalent black carbon (BC) at the Italian Climate Observatory "O. Vittori" (ICO-OV), part of the Mt. Cimone global ...GAW-WMO station (Italy). For this purpose, ICO-OV observations carried out in the period January 2007–June 2009, have been analyzed and correlated with the outputs of the FLEXPART Lagrangian dispersion model to specifically evaluate the influence of biomass burning (BB) and anthropogenic emissions younger than 20 days. During the investigation period, the average O3, CO and BC at ICO-OV were 54 ± 3 ppb, 122 ± 7 ppb and 213 ± 34 ng m−3 (mean ± expanded uncertainty with p < 95%), with clear seasonal cycles characterized by summer maxima and winter minima for O3 and BC and spring maximum and summer minimum for CO. According to FLEXPART outputs, BB impact is maximized during the warm months from July to September but appeared to have a significant contribution to the observed tracers only during specific transport events. We characterised in detail five "representative" events with respect to transport scales (i.e. global, regional and local), source regions and O3, CO and BC variations. For these events, very large variability of enhancement ratios O3/CO (from −0.22 to 0.71) and BC/CO (from 2.69 to 29.83 ng m−3 ppb−1) were observed. CO contributions related with anthropogenic emissions (COant) contributed to 17.4% of the mean CO value observed at ICO-OV, with the warm months appearing particularly affected by transport events of air-masses rich in anthropogenic pollution. The proportion of tracer variability that is described by FLEXPART COant peaked to 37% (in May–September) for CO, 19% (in May–September) for O3 and 32% (in January–April) for BC. During May–September, the analysis of the correlation among CO, O3 and BC as a function of the COant indicated that ICO-OV was influenced by air-masses rich in anthropogenic pollution transported from the regional to the global scale. On the other side, CO and O3 were negatively correlated during October–December, when FLEXPART does not show significant presence of recent anthropogenic emissions and only a few observations are characterized by enhanced BC. Such behaviour may be attributed to an ensemble of processes concurrent in enhancing O3 with low CO (upper troposphere/lower stratosphere intrusions) and to O3 titration by NO in polluted air-masses along with lower photochemical activity. An intermediate situation occurs in January–April when CO and O3 were almost uncorrelated and BC enhancements were associated to relatively old (10 days) anthropogenic emissions.
The Mediterranean basin represents a hot spot area for short-term O3 distribution and anthropogenic contributions to it. This is why we analysed in this work the surface O3 variability observed at ...Mt. Cimone WMO/GAW global station (CMN, 44°12′ N, 10°42′ E, 2165 m a.s.l., Italy) from 1991 to 2011. The measurements performed at this mountain observatory represent the longest surface O3 record at a baseline site in the Mediterranean basin.
Monthly O3 averages at CMN show a typical seasonal cycle characterised by a winter minimum and a spring – summer maxima. The shape of the mean annual variation of O3 is well comparable with those observed at other four baseline sites in the Alps and in the Mediterranean region: Jungfraujoch – Swiss Alps, Sonnblick – Austrian Alps, Mt. Krvavec– Slovenia and Giordan Lightouse – Island of Gozo, Malta. In general, O3 levels at CMN show higher values during warm months, which is likely to be related both to vertical transport of polluted air-masses at regional and continental scales and to enhanced photochemistry.
Here, we also investigate the influence of specific atmospheric processes (i.e. the occurrence of heat-waves, North Atlantic Oscillation, thermal transport of air-masses from the regional PBL and stratospheric intrusions) in affecting O3 variability at CMN.
Overall, a significant positive (95% confidence level) linear trend in monthly O3 mole fraction was observed over the period 1991–2011 (0.21 ± 0.10 nmol/molyr−1) while no trend (-0.02 ± 0.12 nmol/molyr−1) was detected for the 1996–2011, when measurements were carried out by an homogeneous experimental set-up. On a seasonal basis, a positive trend has been observed for 1996–2011 (0.34 ± 0.32 nmol/molyr−1) only for spring. Significant decreases of the seasonal O3 growth-rates have been detected at CMN during 1991–2011 from winter to spring and only for summer during 1996–2011.
•We analysed 19 years of surface O3 data at the Mt. Cimone station (2165 m, Italy).•High O3 values were observed during summer in the Mediterranean region.•NAO variability appeared to affect winter O3, while heat-waves affected summer O3.•O3 increased over 1991–2011 but no trends were detected for the 1996–2011.•Summer O3 growth-rates showed a slowing-down in recent years.
The paper presents the first 2 years of continuous surface ozone (O3 ) observations and systematic assessment of the influence of stratospheric intrusions (SI) at the Nepal Climate Observatory at ...Pyramid (NCO-P; 27°57' N, 86°48' E), located in the southern Himalayas at 5079 m a.s.l.. Continuous O3 monitoring has been carried out at this GAW-WMO station in the framework of the Ev-K2-CNR SHARE and UNEP ABC projects since March 2006. Over the period March 2006-February 2008, an average O3 value of 49±12 ppbv (±1&\delta;) was recorded, with a large annual cycle characterized by a maximum during the pre-monsoon (61±9 ppbv) and a minimum during the monsoon (39±10 ppbv). In general, the average O3 diurnal cycles had different shapes in the different seasons, suggesting an important interaction between the synoptic-scale circulation and the local mountain wind regime. Short-term O3 behaviour in the middle/lower troposphere (e.g. at the altitude level of NCO-P) can be significantly affected by deep SI which, representing one of the most important natural input for tropospheric O3 , can also influence the regional atmosphere radiative forcing. To identify days possibly influenced by SI at the NCO-P, a specially designed statistical methodology was applied to the time series of observed and modelled stratospheric tracers. On this basis, during the 2-year investigation, 14.1% of analysed days were found to be affected by SI. The SI frequency showed a clear seasonal cycle, with minimum during the summer monsoon (1.2%) and higher values during the rest of the year (21.5%). As suggested by back-trajectory analysis, the position of the subtropical jet stream could play an important role in determining the occurrence of deep SI transport on the southern Himalayas. We estimated the fraction of O3 due to SI at the NCO-P. This analysis led to the conclusion that during SI O3 significantly increased by 27.1% (+13 ppbv) with respect to periods not affected by such events. Moreover, the integral contribution of SI (O3S ) to O3 at the NCO-P was also calculated, showing that up to 13.7% of O3 recorded at the measurement site could be possibly attributed to SI. On a seasonal basis, the lowest SI contributions were found during the summer monsoon (less than 0.1%), while the highest were found during the winter period (up to 24.2%). Even considering the rather large uncertainty associated with these estimates, the obtained results indicated that, during non-monsoon periods, high O3 levels could affect NCO-P during SI, thus influencing the variability of tropospheric O3 over the southern Himalayas.
Atmospheric aerosols in the PM10 and PM1 fractions have been sampled at the Global Atmospheric Watch station Mount Cimone, Italy (2165 m above mean sea level) for 3 months during summer 2004, and ...simultaneous size distributions have been derived by means of an optical particle counter. Samples have been analyzed by X‐ray fluorescence, ion chromatography, and thermal‐optical methodology in order to quantify their elemental, ionic, and carbonaceous constituents. The concentration of PM10 was 16.1 ± 9.8 μg m−3 (average and standard deviation). Source apportionment allowed us to identify, quantify and characterize the following aerosol classes: anthropogenic pollution (10 μg m−3), mineral dust (4 μg m−3), and sea salt (0.2 μg m−3). Pollution has been further split into ammonium sulfate (44%), organic matter (42%), and other compounds (14%). The nitrate/sulfate ratio in the polluted aerosol was 0.1. Fine particles have been completely related to the polluted aerosol component, and they represented 70% in weight of pollution. Coarse particles characterized the dust and salt components, and crustal oxides have been found to be the largest responsible for the aerosol concentration variations that occurred during the campaign. Nitrate has also been found in the coarse particles, representing ∼10% of mineral dust. The analysis of the transport mechanisms responsible for aerosol fluctuations permitted us to identify the origin of the major aerosol components: Pollution has been ascribed to regional transport driven by boundary layer meteorology, whereas mineral dust has been related to long‐range transport events originating in the Sahara and Sahel. A particularly significant Saharan episode has been identified on 10 August 2004 (PM10 daily concentration, 69.9 μg m−3). Average elemental ratios for the African dust events were as follows: Si/Al = 2.31, Fe/Ca = 0.94, Ca/Al = 0.90, K/Ca = 0.44, Ti/Ca = 0.11, and Ti/Fe = 0.12.
In this work, we analysed reactive gases (O3, CO, NOx) and aerosol properties (eqBC, σs and particle number concentration) collected at the WMO/GAW Mt. Cimone station (2165 m a.s.l., Italy) during ...the summer of 2012 in the framework of PEGASOS project. The major aim of this experiment is providing a characterization of the variability of summer atmospheric composition over the central Mediterranean basin, which is considered as a global “hot-spot” for atmospheric pollution and climate change.
The atmospheric tracers have been analysed as a function of (i) meteorological parameters, (ii) synoptic-scale circulation and (iii) anthropogenic emission source proximity as estimated by O3/NOx ratio variability. In particular, we identified three O3/NOx regimes which tagged the distance of anthropogenic sources: near outflow (23% of hourly data), far-outflow (38% of data) and background (39% of data). The highest levels of anthropogenic pollutants (e.g. O3, CO, eqBC, accumulation particles) were concomitant with fresh emissions from northern Italy under near-outflow conditions: once injected to the free troposphere, these air-masses, rich in pollutants and climate-forcers (i.e. O3, eqBC) and soil dust, can be spread over a large region, thus significantly affecting regional climate. Moreover, based on the anthropogenic source proximity, atmospheric tracer variability and synoptic-scale atmospheric circulation, we categorized and characterised four types of atmospheric regimes associated with (1) air-mass transport from the free troposphere, (2) transport of fresh emitted pollutants from the PBL, (3) transport at regional/continental scale of aged anthropogenic (4) transport of air-mass rich in mineral dust from northern Africa (i.e. coming from more than 1000 km).
Lastly, by analysing the probability density functions (PDFs) of trace gases and aerosol properties, “fingerprints” of the mentioned atmospheric regimes were pointed out. Such information is useful for the implementation of early-warning services, for the timely detection of event occurrence as well as for the definition of observation-based diagnostic for model verifications.
•Mt. Cimone (Italy) is strategic to study Mediterranean summer atmospheric composition.•We investigate processes affecting summer trace gas and aerosols at Mt. Cimone.•Impact of different atmospheric regimes was investigated.•77% of observations can be tagged to aged emissions or background conditions.•Tracer probability density functions are able to detect specific event.
To study the influence of polluted air-mass transport carrying ozone （O3） and black carbon （BC） in the high Himalayas, since March 2006 the Nepal Climate Observatory at Pyramid （NCO-P） GAW-WMO global ...station （Nepal, 5079 m a.s.l.） is operative. During the first 5-year measurements, the O3 and BC concentrations have shown a mean value of 48 ± 12 ppb （± standard deviation） and 208 ± 374 ng/m3, respectively. Both O3 and BC showed well defined seasonal cycles with maxima during pre-monsoon （O3 ： 61.3 ± 7.7 ppbV; BC： 444 ± 433 ng/m3） and minima during the summer monsoon （O3 ： 40.1 ± 12.4 ppbV; BC： 64 ± 101 ng/m3）. The analysis of the days characterised by the presence of a significant BC increase with respect to the typical seasonal cycle identified 156 days affected by ＂acute＂ pollution events, corresponding to 9.1% of the entire data-set. Such events mostly occur in the pre-monsoon period, when the O3 diurnal variability is strongly related to the transport of polluted air-mass rich on BC. On average, these ＂acute＂ pollution events were characterised by dramatic increases of BC （352%） and O3 （29%） levels compared with the remaining days.
PDF
