scholarly journals Increased inorganic aerosol fraction contributes to air pollution and haze in China

2019 ◽  
Vol 19 (9) ◽  
pp. 5881-5888 ◽  
Author(s):  
Yonghong Wang ◽  
Yuesi Wang ◽  
Lili Wang ◽  
Tuukka Petäjä ◽  
Qiaozhi Zha ◽  
...  
Keyword(s):  
Satellite Observation ◽  
Pollution Level ◽  
Mass Fractions ◽  
Particle Pollution ◽  
Aerosol Fraction ◽  
Inorganic Aerosol ◽  
Haze Days ◽  
Inorganic Precursors ◽  
Reduced Surface

Abstract. The detailed formation mechanism of an increased number of haze events in China is still not very clear. Here, we found that reduced surface visibility from 1980 to 2010 and an increase in satellite-derived columnar concentrations of inorganic precursors from 2002 to 2012 are connected with each other. Typically, higher inorganic mass fractions lead to increased aerosol water uptake and light-scattering ability in elevated relative humidity. Satellite observation of aerosol precursors of NO2 and SO2 showed increased concentrations during the study period. Our in situ measurement of aerosol chemical composition in Beijing also confirmed increased contribution of inorganic aerosol fraction as a function of the increased particle pollution level. Our investigations demonstrate that the increased inorganic fraction in the aerosol particles is a key component in the frequently occurring haze days during the study period, and particularly the reduction of nitrate, sulfate and their precursor gases would contribute towards better visibility in China.

scholarly journals Increased inorganic aerosol fraction contributes to air pollution and haze in China

2018 ◽  
Author(s):  
Yonghong Wang ◽  
Yuesi Wang ◽  
Lili Wang ◽  
Tuukka Petäjä ◽  
Qiaozhi Zha ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Satellite Observation ◽  
Pollution Level ◽  
Mass Fractions ◽  
Particle Pollution ◽  
Aerosol Fraction ◽  
Inorganic Aerosol ◽  
Haze Days ◽  
Reduced Surface

Abstract. The detailed formation mechanism of increased number of haze events in China is still not very clear. Here, we found that reduced surface visibility and an increase in satellite derived columnar concentration of inorganic precursor concentrations are connected with each other. Typically higher inorganic mass fractions lead to increased aerosol water uptake and light scattering ability in elevated relative humidity. Satellite observation of aerosol precursors of NO2 and SO2 showed increased concentrations during study period. Our in-situ measurement of aerosol chemical composition in Beijing also confirmed increased contribution of inorganic aerosol fraction as a function of increased particle pollution level. Our investigations demonstrate that the increased inorganic fraction in the aerosol particles is a key component in the frequently occurring haze days during studying period, and particularly the reduction of nitrate, sulfate and their precursor gases would contribute towards better air quality in China.

scholarly journals Microwave Sensors for In Situ Monitoring of Trace Metals in Polluted Water

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3147
Author(s):  
Ilaria Frau ◽  
Stephen Wylie ◽  
Patrick Byrne ◽  
Patrizia Onnis ◽  
Jeff Cullen ◽  
...  
Keyword(s):  
Trace Metals ◽  
In Situ Monitoring ◽  
Polluted Water ◽  
Pollution Level ◽  
Mining Areas ◽  
Low Concentrations ◽  
The Uk ◽  
Microwave Sensors ◽  
Immediate Response

Thousands of pollutants are threatening our water supply, putting at risk human and environmental health. Between them, trace metals are of significant concern, due to their high toxicity at low concentrations. Abandoned mining areas are globally one of the major sources of toxic metals. Nowadays, no method can guarantee an immediate response for quantifying these pollutants. In this work, a novel technique based on microwave spectroscopy and planar sensors for in situ real-time monitoring of water quality is described. The sensors were developed to directly probe water samples, and in situ trial measurements were performed in freshwater in four polluted mining areas in the UK. Planar microwave sensors were able detect the water pollution level with an immediate response specifically depicted at three resonant peaks in the GHz range. To the authors’ best knowledge, this is the first time that planar microwave sensors were tested in situ, demonstrating the ability to use this method for classifying more and less polluted water using a multiple-peak approach.

scholarly journals The variation characteristics and possible sources of atmospheric water-soluble ions in Beijing

2016 ◽  
Author(s):  
Pengfei Liu ◽  
Chenglong Zhang ◽  
Yujing Mu ◽  
Chengtang Liu ◽  
Chaoyang Xue ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Water Soluble ◽  
Effective Control ◽  
Pollution Level ◽  
Summer Maize ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Variation Characteristics ◽  
Oxidation Ratio ◽  
Haze Days

Abstract. The North China plain (NCP) including Beijing is currently suffering from severe haze events due to high pollution level of atmospheric fine particles called PM2.5. To mitigate the serious pollution status, identification of the sources of PM2.5 is urgently needed for the effective control measures. A total of 235 daily samples of PM2.5 were collected in Beijing through the year of 2014, and the variation characteristics of water-soluble ions (WSIs) in the PM2.5 were comprehensively analyzed for recognizing their possible sources. The results indicated that the periodic emissions from farmers' activities made evident contribution to the atmospheric WSIs in Beijing. The unusually high ratio of Cl− to Na+ in summer could be rationally explained by the prevailing fertilization of NH4Cl for planting summer maize in the vast area of NCP. The remarkable elevation of Cl− in winter was ascribed to coal combustion for heating by farmers. The most serious pollution episodes in autumn were coincident with significant elevation of Ca2+ which was ascribed to be from harvest of the summer maize and tillage for planting the winter wheat. The mineral dust emission from the harvest and tillage not only increased the atmospheric concentrations of the primary pollutants, but also greatly accelerated formation of sulfate and nitrate through heterogeneous reactions of NO2 and SO2 on the mineral dust. The relatively high concentration of K+ in winter and autumn further confirmed that crop straw burning made evident contribution to atmospheric PM2.5 in Beijing. The backward trajectories also indicated that the highest concentrations of WSIs usually occurred in the air parcel from southwest/south regions with high density of farmers. In addition, the values of nitrogen oxidation ratio (NOR) and the sulfur oxidation ratio (SOR) were found to be much higher under haze days than under non-haze days, implying that formation of sulfate and nitrate was greatly accelerated through heterogeneous or multiphase reactions of NO2 and SO2 on PM2.5.

scholarly journals In situ observations of aerosol particles remaining from evaporated cirrus crystals: Comparing clean and polluted air masses

2002 ◽  
Vol 2 (5) ◽  
pp. 1599-1633 ◽  
Author(s):  
M. Seifert ◽  
J. Ström ◽  
R. Krejci ◽  
A. Minikin ◽  
A. Petzold ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Aerosol Particles ◽  
Pollution Level ◽  
Size Distributions ◽  
Number Density ◽  
Particle Volume ◽  
The North ◽  
In Situ Observations

Abstract. In situ observations of aerosol particles contained in cirrus crystals are presented and compared to interstitial aerosol size distributions (non-activated particles in between the cirrus crystals). The observations were conducted in cirrus clouds in the Southern and Northern Hemisphere mid-latitudes during the INCA project. The first campaign in March and April 2000 was performed from Punta Arenas, Chile (54° S) in pristine air. The second campaign in September and October 2000 was performed from Prestwick, Scotland (53° N) in the vicinity of the North Atlantic flight corridor. Size distribution measurements of crystal residuals (particles remaining after evaporation of the crystals) show that small aerosol particles (Dp < 0.1µm) dominate the number density of residuals. The crystal residual size distributions were significantly different in the two campaigns. On average the residual size distributions were shifted towards larger sizes in the Southern Hemisphere. For a given integral residual number density, the calculated particle volume was on average three times larger in the Southern Hemisphere. This may be of significance to the vertical redistribution of aerosol mass by clouds in the tropopause region. In both campaigns the mean residual size increased with increasing crystal number density. The observations of ambient aerosol particles were consistent with the expected higher pollution level in the Northern Hemisphere. The fraction of residual particles only contributes to approximately a percent or less of the total number of particles, which is the sum of the residual and interstitial particles.

MARINE-EO project: Monitoring and forecast of eutrophication around fish farms, a Maliakos Gulf case (Eastern Mediterranean).

2021 ◽  
Author(s):  
Amandine Declerck ◽  
Matthias Delpey ◽  
Thibaut Voirand ◽  
Ioanna Varkitzi
Keyword(s):  
Water Quality ◽  
High Resolution ◽  
Real Time ◽  
Chlorophyll A ◽  
Satellite Observation ◽  
Risk Level ◽  
Fish Farms ◽  
Ocean Modelling ◽  
Monitoring And Forecasting

&lt;p&gt;Keywords: eutrophication; high resolution ocean modeling ; Chla satellite data ; biogeochemistry&lt;/p&gt;&lt;p&gt;Maliakos Gulf corresponds to mesotrophic waters that can reach eutrophic conditions and are occasionally subject to Harmful Algal Blooms (HAB) (Varkitzi et al. 2018). At the same time, it is an important fish farming and aquaculture production area. A large issue is thus related to the monitoring and forecasting of the risk of occurrence of algae blooms in the Gulf. For this purpose, the present study couples predictions from a high-resolution numerical ocean model with satellite observation to improve the monitoring and anticipation of threats for the local fish farms induced by occasional eutrophication.&lt;/p&gt;&lt;p&gt;This solution is developed in the frame of the MARINE-EO project (https://marine-eo.eu/). It combines satellite observation with high-resolution ocean modelling to provide detailed information as a support to fish farms management and operations. It is implemented in an operational platform, which provides continuous information in real time as well as short term predictions. The deployed solution uses CMEMS physical products as an input data and offers to refine this solution in order to provide a local information on site using a downscaling strategy. High resolution satellite products and ocean modelling allow to include the impact of local coastal processes on currents and water quality parameters to provide a proper monitoring and forecasting solution at the scale of a specific fish farm.&lt;/p&gt;&lt;p&gt;To model specific eutrophication processes, a NPZD (Nutrients-Phytoplankton-Zooplankton-Detritus) biogeochemical model is used. Included in the MOHID Water modelling system, the water quality module (Mateus, 2006) considering 18 properties: nutrients and organic matter (nitrogen, phosphorus and silica biogeochemical cycles), oxygen and organisms (phytoplankton and zooplankton) was deployed in the western Aegean Sea. The simulated chlorophyll a concentrations are used to compute a risk level for the eutrophication occurrence. To complete this indicator, another risk level was based on the eutrophication variation following Primpas et al. (2010) formulation. In addition to model forecasts, ocean color observations from the Sentinel-2 MSI and Landsat-8 OLI sensors are used to provide high resolution chlorophyll a concentrations maps in case of bloom events. The processing chain uses the sixth version of the Quasi-Analytical Algorithm initially developed by Lee et al. (2002) and an empirical relation based on a database built using the HydroLight software to compute chlorophyll a concentration.&lt;/p&gt;&lt;p&gt;Two past eutrophication events monitored in situ (Varkitzi et al. 2018) were studied to assess the accuracy of the developed tool. Although few in situ data were available on environmental input (as rivers flow and nutrient concentrations), it was possible using statistics to reproduce qualitatively these blooms. Finally, an operational demonstration was conducted during 2 months of the 2020 autumn season, to showcase real time monitoring and predictive perspectives.&lt;/p&gt;

scholarly journals Simulating Secondary Inorganic Aerosols using the chemistry transport model MOCAGE version R2.15.0

2015 ◽  
Vol 8 (4) ◽  
pp. 3593-3651 ◽  
Author(s):  
J. Guth ◽  
B. Josse ◽  
V. Marécal ◽  
M. Joly
Keyword(s):  
North America ◽  
Transport Model ◽  
Regional Scale ◽  
In Situ Measurements ◽  
Aerosol Composition ◽  
Chemistry Transport Model ◽  
Inorganic Aerosols ◽  
Modis Aod ◽  
Inorganic Aerosol

Abstract. In this study we develop a Secondary Inorganic Aerosol (SIA) module for the chemistry transport model MOCAGE developed at CNRM. Based on the thermodynamic equilibrium module ISORROPIA II, the new version of the model is evaluated both at the global scale and at the regional scale. The results show high concentrations of secondary inorganic aerosols in the most polluted regions being Europe, Asia and the eastern part of North America. Asia shows higher sulfate concentrations than other regions thanks to emissions reduction in Europe and North America. Using two simulations, one with and the other without secondary inorganic aerosol formation, the model global outputs are compared to previous studies, to MODIS AOD retrievals, and also to in situ measurements from the HTAP database. The model shows a better agreement in all geographical regions with MODIS AOD retrievals when introducing SIA. It also provides a good statistical agreement with in situ measurements of secondary inorganic aerosol composition: sulfate, nitrate and ammonium. In addition, the simulation with SIA gives generally a better agreement for secondary inorganic aerosols precursors (nitric acid, sulfur dioxide, ammonia) in particular with a reduction of the Modified Normalised Mean Bias (MNMB). At the regional scale, over Europe, the model simulation with SIA are compared to the in situ measurements from the EMEP database and shows a good agreement with secondary inorganic aerosol composition. The results at the regional scale are consistent with those obtained with the global simulations. The AIRBASE database was used to compare the model to regulated air quality pollutants being particulate matter, ozone and nitrogen dioxide concentrations. The introduction of the SIA in MOCAGE provides a reduction of the PM2.5 MNMB of 0.44 on a yearly basis and even 0.52 on a three spring months period (March, April, May) when SIA are maximum.

4H-SiC Epitaxial Growth on Carbon-Face Substrates with Reduced Surface Roughness

2006 ◽  
Vol 527-529 ◽  
pp. 153-158 ◽  
Author(s):  
Takashi Aigo ◽  
M. Sawamura ◽  
Tatsuo Fujimoto ◽  
Masakazu Katsuno ◽  
Hirokatsu Yashiro ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Substrate Temperature ◽  
Epitaxial Layer ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Semiconductor Interface ◽  
Surface Morphologies ◽  
Reduced Surface ◽  
Quality Metal

4H-SiC epitaxial layers on Carbon-face (C-face) substrates were grown by a low-pressure hot-wall type chemical vapor deposition system. The C-face substrates were prepared by fine mechanical polishing using diamond abrasives with the grit size of 0.25 %m and in-situ HCl etching at 1400°C, which produced surface roughness of 0.27 nm. The use of the smooth substrates made it possible to decrease the substrate temperature and specular surface morphologies were realized at C/Si ratios of 1.5 or less both for a substrate temperature of 1550°C and for that of 1500°C. Surface roughness of 0.26 nm and the residual donor concentration of 6.7×1014 cm-3 were obtained for a C-face epitaxial layer grown at a C/Si ratio of 1.5 and at a substrate temperature of 1550°C. Schottky barrier diodes were fabricated on a non-doped C-face epitaxial layer grown at 1500°C and it was verified that a high quality metal-semiconductor interface was formed on the epitaxial layer.

scholarly journals Arctic stratospheric dehydration – Part 1: Unprecedented observation of vertical redistribution of water

2013 ◽  
Vol 13 (22) ◽  
pp. 11503-11517 ◽  
Author(s):  
S. M. Khaykin ◽  
I. Engel ◽  
H. Vömel ◽  
I. M. Formanyuk ◽  
R. Kivi ◽  
...  
Keyword(s):  
Water Vapour ◽  
Stratospheric Ozone ◽  
Measurement Techniques ◽  
Thick Layer ◽  
Satellite Observation ◽  
The Arctic ◽  
Ice Particles ◽  
Climate Interactions ◽  
Stratospheric Clouds

Abstract. We present high-resolution measurements of water vapour, aerosols and clouds in the Arctic stratosphere in January and February 2010 carried out by in situ instrumentation on balloon sondes and high-altitude aircraft combined with satellite observations. The measurements provide unparalleled evidence of dehydration and rehydration due to gravitational settling of ice particles. An extreme cooling of the Arctic stratospheric vortex during the second half of January 2010 resulted in a rare synoptic-scale outbreak of ice polar stratospheric clouds (PSCs) remotely detected by the lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite. The widespread occurrence of ice clouds was followed by sedimentation and consequent sublimation of ice particles, leading to vertical redistribution of water inside the vortex. A sequence of balloon and aircraft soundings with chilled mirror and Lyman- α hygrometers (Cryogenic Frostpoint Hygrometer, CFH; Fast In Situ Stratospheric Hygrometer, FISH; Fluorescent Airborne Stratospheric Hygrometer, FLASH) and backscatter sondes (Compact Optical Backscatter Aerosol Detector, COBALD) conducted in January 2010 within the LAPBIAT (Lapland Atmosphere-Biosphere Facility) and RECONCILE (Reconciliation of Essential Process Parameters for an Enhanced Predictability of Arctic Stratospheric Ozone Loss and its Climate Interactions) campaigns captured various phases of this phenomenon: ice formation, irreversible dehydration and rehydration. Consistent observations of water vapour by these independent measurement techniques show clear signatures of irreversible dehydration of the vortex air by up to 1.6 ppmv in the 20–24 km altitude range and rehydration by up to 0.9 ppmv in a 1 km thick layer below. Comparison with space-borne Aura MLS (Microwave Limb Sounder) water vapour observations allow the spatiotemporal evolution of dehydrated air masses within the Arctic vortex to be derived and upscaled.

scholarly journals Field characterization of the PM<sub>2.5</sub> Aerosol Chemical Speciation Monitor: insights into the composition, sources, and processes of fine particles in eastern China

2017 ◽  
Vol 17 (23) ◽  
pp. 14501-14517 ◽  
Author(s):  
Yunjiang Zhang ◽  
Lili Tang ◽  
Philip L. Croteau ◽  
Olivier Favez ◽  
Yele Sun ◽  
...  
Keyword(s):  
Chemical Speciation ◽  
Fine Particles ◽  
Eastern China ◽  
Temporal Variations ◽  
Inorganic Aerosols ◽  
Mass Fractions ◽  
Highly Correlated ◽  
First Time

Abstract. A PM2.5-capable aerosol chemical speciation monitor (Q-ACSM) was deployed in urban Nanjing, China, for the first time to measure in situ non-refractory fine particle (NR-PM2.5) composition from 20 October to 19 November 2015, along with parallel measurements of submicron aerosol (PM1) species by a standard Q-ACSM. Our results show that the NR-PM2.5 species (organics, sulfate, nitrate, and ammonium) measured by the PM2.5-Q-ACSM are highly correlated (r2 > 0.9) with those measured by a Sunset Lab OC  /  EC analyzer and a Monitor for AeRosols and GAses (MARGA). The comparisons between the two Q-ACSMs illustrated similar temporal variations in all NR species between PM1 and PM2.5, yet substantial mass fractions of aerosol species were observed in the size range of 1–2.5 µm. On average, NR-PM1−2.5 contributed 53 % of the total NR-PM2.5, with sulfate and secondary organic aerosols (SOAs) being the two largest contributors (26 and 27 %, respectively). Positive matrix factorization of organic aerosol showed similar temporal variations in both primary and secondary OAs between PM1 and PM2.5, although the mass spectra were slightly different due to more thermal decomposition on the capture vaporizer of the PM2.5-Q-ACSM. We observed an enhancement of SOA under high relative humidity conditions, which is associated with simultaneous increases in aerosol pH, gas-phase species (NO2, SO2, and NH3) concentrations and aerosol water content driven by secondary inorganic aerosols. These results likely indicate an enhanced reactive uptake of SOA precursors upon aqueous particles. Therefore, reducing anthropogenic NOx, SO2, and NH3 emissions might not only reduce secondary inorganic aerosols but also the SOA burden during haze episodes in China.

scholarly journals Inferring iron oxides species content in atmospheric mineral dust from DSCOVR EPIC observations

2021 ◽  
Author(s):  
Sujung Go ◽  
Alexei Lyapustin ◽  
Gregory L. Schuster ◽  
Myungje Choi ◽  
Paul Ginoux ◽  
...  
Keyword(s):  
Refractive Index ◽  
Iron Oxide ◽  
Middle East ◽  
Iron Oxides ◽  
Mineral Dust ◽  
Dust Particles ◽  
Refractive Indices ◽  
Mass Fractions ◽  
Mass Concentrations

Abstract. The iron-oxide content of dust in the atmosphere and most notably its apportionment between hematite (α-Fe2O3) and goethite (α-FeOOH) are key determinants in quantifying dust's light absorption, its top of atmosphere UV radiances used for dust monitoring, and ultimately shortwave dust direct radiative effects (DRE). Hematite and goethite column mass concentrations and iron-oxide mass fractions of total dust mass concentration were retrieved from the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) measurements in the ultraviolet–visible (UV–Vis) channels. The retrievals were performed for dust-identified aerosol plumes using aerosol optical depth (AOD) and spectral imaginary refractive index provided by the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm over six continental regions (North America, North Africa, West Asia, Central Asia, East Asia, and Australia). The dust particles are represented as an internal mixture of non-absorbing host and absorbing hematite and goethite. We use the Maxwell–Garnett effective medium approximation with carefully selected complex refractive indices of hematite and goethite that produce mass fractions of iron oxides species consistent with in situ values found in the literature to derive the hematite and goethite volumetric/mass concentrations from MAIAC EPIC products. We compared the retrieved hematite and goethite concentrations with in situ dust aerosol mineralogical content measurements, as well as with published data. Our data display variations within the published range of hematite, goethite, and iron-oxide mass fractions for pure mineral dust cases. A specific analysis is presented for 15 sites over the main dust source regions. Sites in the central Sahara, Sahel, and Middle East exhibit a greater temporal variability of iron oxides relative to other sites. Niger site (13.52° N, 2.63° E) is dominated by goethite over Harmattan season with median of ~2 weight percentage (wt.%) of iron-oxide. Saudi Arabia site (27.49° N, 41.98° E) over Middle East also exhibited surge of goethite content with the beginning of Shamal season. The Sahel dust is richer in iron-oxide than Saharan and northern China dust except in Summer. The Bodélé Depression area shows a distinctively lower iron-oxide concentration (~1 wt. %) throughout the year. Finally, we show that EPIC data allow to constrain the hematite refractive index. Specifically, we select 5 out of 13 different number of hematite refractive indices widely variable in published laboratory studies by constraining the iron-oxide mass ratio to the known measured values. Provided climatology of hematite and goethite mass fractions across main dust regions of the Earth will be useful for dust shortwave DRE studies and climate modeling. 

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