Mixing Of Dust Research Articles

Mineralogy and geochemistry of Asian dust: dependence on migration path, fractionation, and reactions with polluted air

Abstract. Mineralogical and geochemical data are essential for estimating the effects of long-range transport of Asian dust on the atmosphere, biosphere, cryosphere, and pedosphere. However, consistent long-term data sets of dust samples are rare. This study analyzed 25 samples collected during 14 Asian dust events occurring between 2005 and 2018 on the Korean Peninsula and compared them to 34 soil samples (<20 µm) obtained from the Mongolian Gobi Desert, which is a major source of Asian dust. The mineralogical and geochemical characteristics of Asian dust were consistent with those of fine source soils in general. In dust, clay minerals were most abundant, followed by quartz, plagioclase, K-feldspar, calcite, and gypsum. The trace element contents were influenced by the mixing of dust with polluted air and the fractionation of rare earth elements. Time-series analyses of the geochemical data of dust, combined with satellite remote sensing images, showed a significant increase in the Ca content in the dust crossing the Chinese Loess Plateau and the sandy deserts of northern China. Calcareous sediments in the sandy deserts and pedogenic calcite-rich loess are probable sources of additional Ca. Dust-laden air migrating toward Korea mixes with polluted air over East Asia. Gypsum, a minor mineral in source soils, was formed by the reaction between calcite and pollutants. This study describes not only the representative properties of Asian dust but also their variation according to the migration path, fractionation, and atmospheric reactions.

MODERNIZATION OF DEVICES FOR PURIFICATION OF AIR FROM SOLID HIGH-DISPERSED AEROSOLS

A device for cleaning solid particles with a dispersion of 0.1 μm is proposed. The principle of the apparatus is based on coagulation of particles on slots perforated in the form of slots, using irrigation of contaminated air with water through nozzles with a dispersed composition from 2.0 microns to 10 microns. When a threephase fl ow passes through the slots of the fi rst separator plate, turbulent coagulation occurs due to turbulence of the fl ow in streams with a small turbulence scale, which leads to particle coarsening. When the jet runs onto the second plate, a boundary layer is formed that has an increased viscosity to the components of the jet. Viscosity is formed due to the sedimentation and mixing of water particles and dust (including coarsened) on the surface of the second plate, where particles are mainly deposited. The dependences of the apparatus effi ciency on the width of the slots and their mutual arrangement on the fi rst and second plates, the combination of which provides a mode of increased coagulation and high effi - ciency of particle capture by the apparatus, are revealed.

Zinc isotope revealing zinc's sources and transport processes in karst region

The heavy metal pollution, mainly caused by mining-related activities over extended period of time, is imposing a severe threat to environments and human health. Environmental systems, including rivers and paddy soils, have been widely established as one of the key sinks of potentially harmful metals. Aiming to understand contamination sources and pathways of Zn in karst area, we studied the Zn concentration and isotope composition of river waters, sediments, mine tailings, paddy soils, dust and three soil profiles with different levels of Zn-pollution around a Zn-mine, southwestern China. The distinct Zn isotope compositions among tailing (−0.42 ± 0.02‰), dust (−0.24 ± 0.02‰), and geogenic soil (−0.16 ± 0.03‰) allowed for separation of anthropogenic-Zn from native Zn. In the plot of δ66Zn value and 1/Zn, all samples can be explained by the mixing of three components: mining-input, agricultural input, and background. Evolution of these three components helps produce direct sources: dust and geogenic soil. Under this framework, the Zn pollution in paddy soil and sediment can be explained by mixing of mine-tailing, dust, and geogenic soil. Our study shows that the contamination of mine drainage is limited in the area due to the relatively high pH buffered by carbonate in karst area. While the dust contributes most of the anthropogenic Zn with an average value of 19.5%. The dominant pathway of anthropogenic Zn from dust to paddy soil or sediment is through the long-term wind dispersion of fine-grained material from the tailing and the physical transmission. Under the special hydrogeological conditions of karst, mining activities will increase the migration of heavy metals. The Fe-Al oxides control the migration of Zn in soil profile, but probably do not lead to significantly Zn isotopes fractionation. This further enhances the reliability of Zn isotopes as a “fingerprint” in karst area.

Direct Radiative Effect of Absorbing Aerosols: Sensitivity to Mixing State, Brown Carbon, and Soil Dust Refractive Index and Shape

Key Points Aerosol absorption is sensitive to mixing state, brown carbon, and soil dust optical properties Blanching reduces coating brown carbon radiative effect; soil dust radiative effect uncertainty due to the refractive index is large Radiative effect of radiation‐absorbing aerosol total uncertainty is mainly due to dust refractive index and brown carbon treatment

Analysis of a Severe Regional Haze-fog-dust Episode over North China in Autumn by Using Multiple Observation Data

ABSTRACT The mixing of dust and haze is an important factor in the variation of fine particles. In this study, multiple observation data were used to analyze the characteristics and formation of a haze-fog-dust event that occurred in North China between November 23 and November 30 of 2018. This episode can be roughly divided into two stages, haze-fog and dust, with the transition occurring on November 27. Our analysis shows that stable weather conditions and temperature inversions in North China caused the haze-fog event (November 23–26), during which the PM2.5 concentration gradually increased. After November 27, the arrival of cold air accompanied by dust activity rendered meteorological conditions favorable to air quality in the northern part but not the central or southern part of North China. Instead, continuous adverse conditions and the dust backflow, which trapped dust aerosols in the southern part of North China for nearly two days, were responsible for high PM2.5 concentrations in Jinan and Zhengzhou after November 27 (146 and 156 µg m–3 vs. 114 and 144 µg m–3 before November 27, respectively). This study highlights the effect of dust transport on regional environmental pollution during the autumn and the winter.

Development of Simulator for Mine Dust and Disturbing Environment

In order to explore the influence of interference factors on the light scattering dust detector, a spherical experimental cabin is developed, which can control the particle size, mass concentration distribution and relative humidity of dust. Combining with the fluid simulation experiment, the best method for rapid mixing dust is determined. The particle size, mass concentration and relative humidity of the dust are monitored and controlled by the sensor system inside the spherical cabin and the upper computer software. The wireless transmission between the sensor and the upper computer is realized. The control range of particle size is 0.5-10 μm, mass concentration is 0-10 mg/m3 and relative humidity is 5-85%.

Long-Term Aerosol Trends and Variability over Central Saudi Arabia Using Optical Characteristics from Solar Village AERONET Measurements

Natural and anthropogenic aerosols over the Kingdom of Saudi Arabia (KSA) play a major role in affecting the regional radiation budget. The long-term variability of these aerosols’ physical and optical parameters, including aerosol optical depth (AOD) and Ångström exponent (α), were measured at a location near central KSA using the Solar Village (SV) AERONET (Aerosol Robotic Network) station during the period December 1999–January 2013. The AERONET measurements show an overall increase in AOD on an annual basis. This upward trend is mainly attributed to a prolonged increase in the monthly/seasonal mean AOD during March–June and during August–September. In contrast, lower AOD values were observed during November–December. This can be attributed to a low frequency of dust outbreaks and higher precipitation rates. An overall, weak declining trend in α was observed, except during the summer. The spring and summer seasons experienced a pronounced increase in the number of coarse particles (~2 µm) during April 2006–January 2013 as compared to December 1999–March 2006, suggesting an increase in natural aerosol loadings. Using the HYSPLIT model, it was found that the March 2009 dust storm contributed to the mixing of long-transported dust with anthropogenic local emissions near the SV. The results suggest that extensive industrial activity contributed to the increase of anthropogenic emissions over KSA during the period April 2006–January 2013.

High-resolution radiative transfer modelling of M33

ABSTRACT In this work, we characterize the contributions from both ongoing star formation and the ambient radiation field in Local Group galaxy M33, as well as estimate the scale of the local dust-energy balance (i.e. the scale at which the dust is re-emitting starlight generated in that same region) in this galaxy through high-resolution radiative transfer (RT) modelling, with defined stellar and dust geometries. We have characterized the spectral energy distribution (SED) of M33 from UV to sub-mm wavelengths, at a spatial scale of 100 pc. We constructed input maps of the various stellar and dust geometries for use in the RT modelling. By modifying our dust mix (fewer very small carbon grains and a lower silicate-to-carbon ratio as compared to the Milky Way), we can much better fit the sub-mm dust continuum. Using this new dust composition, we find that we are able to well reproduce the observed SED of M33 using our adopted model. In terms of stellar attenuation by dust, we find a reasonably strong, broad UV bump, as well as significant systematic differences in the amount of dust attenuation when compared to standard SED modelling. We also find discrepancies in the residuals of the spiral arms versus the diffuse interstellar medium (ISM), indicating a difference in properties between these two regimes. The dust emission is dominated by heating due to the young stellar populations at all wavelengths (∼80 per cent at 10 $\mu$m to ∼50 per cent at 1 mm). We find that the local dust-energy balance is restored at spatial scales greater than around 1.5 kpc.

Impact of dust-polluted convective clouds over the Tibetan Plateau on downstream precipitation

Based on satellite observations and reanalysis datasets, this study focuses on the effect of aerosols on clouds over the Tibetan Plateau (TP) and the impact of dust-polluted convective clouds on precipitation over downstream regions. A heavy dust event is detected by Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) over the northern slope of the TP on 16 July and 17 July 2016. The high aerosol optical depth (AOD) values are mainly distributed over the northern slope of the TP. Simultaneously, the CloudSat satellite observes deep convective clouds over the northern slope area of the TP, in which convective clouds and dust mix at the same height. With the AOD increasing from 16 July to its peak on 17 July, the ice particle size decreases to a minimum, and convective clouds develop at higher heights because of the prolonged cloud life. Accordingly, a larger ice water path (IWP) is induced by the development of convective clouds that move eastwardly from 16 to 17 July. In the following days, under favorable meteorological conditions, some of the developed convective clouds continuously move eastward and merge with the convective cloud clusters along the motion path, which induces significant precipitation over the Yangtze River basin on 17 July. Furthermore, driven by the northward wind, some developed convective cloud clusters move northward and induce strong precipitation over North China on 19 July. The indirect effect of dust aerosols over the TP could enhance the plateau's cloud development and potentially contribute to downstream precipitation, which is a meaningful factor for weather forecasting.

The Fornax 3D project: dust mix and gas properties in the centre of early-type galaxy FCC 167

Galaxies continuously reprocess their interstellar material. We can therefore expect changing dust grain properties in galaxies that have followed different evolutionary pathways. Determining the intrinsic dust grain mix of a galaxy helps in reconstructing its evolutionary history. Early-type galaxies occasionally display regular dust lanes in their central regions. Owing to the relatively simple geometry and composition of their stellar bodies, these galaxies are ideal to disentangle dust mix variations from geometric effects. We therefore modelled the various components of such a galaxy (FCC 167). We reconstructed its recent history and investigated the possible fate of the dust lane. Observations from MUSE and the Atacama Large Millimeter/submillimeter Array (ALMA) reveal a nested interstellar medium structure. An ionised-gas disc pervades the central regions of FCC 167, including those occupied by the main dust lane. Inward of the dust lane, we also find a disc/ring of cold molecular gas where stars are forming and HII regions contribute to the ionised-gas emission. Further in, the gas ionisation points towards an active galactic nucleus and the fuelling of a central supermassive black hole from its surrounding ionised and molecular reservoir. Observational constraints and radiative transfer models suggest the dust and gas are distributed in a ring-like geometry and the dust mix lacks small grains. The derived dust destruction timescales from sputtering in hot gas are short, and we conclude that the dust must be strongly self-shielding and clumpy or will quickly be eroded and disappear. Our findings show how detailed analyses of individual systems can complement statistical studies of dust-lane ETGs.

Variability of depolarization of aerosol particles in the megacity of Beijing: implications for the interaction between anthropogenic pollutants and mineral dust particles

Abstract. East Asia is suffering from severe air pollution problems due to intensive anthropogenic emissions and natural mineral dust aerosols. During transport, the aerosol particles undergo complex mixing processes, resulting in great impacts on regional air quality, human health and climate. In this study, we conducted a long-term observation using an optical particle counter equipped with a polarization detection module (POPC) at an urban site in Beijing. Mass concentrations of both PM2.5 and PM10 estimated from POPC compared well with ground-based measurements. The results revealed that the observed depolarization ratio (δ, termed as the ratio of the intensity of the s-polarized signal to the intensity of the 120∘ backward scattering signal [s/(s+p)]) for aerosol particles in the fine mode was generally much lower in summer than that in spring as a result of predominance of different aerosol types. Mineral dust particles in the coarse mode normally had a large δ value (0.3±0.05) owing to their nonspherical shape; however, particles in the fine mode mostly had water-soluble compositions, which led to an apparent decrease of their δ values in particular high relative humidity (RH) conditions. Because the observation site was subject to the impact of frequent dust events in spring, the δ value of particle at 1 µm was almost twice as high as that (0.07±0.01) in summer. Based on size-resolved δ values, anthropogenic pollutants, mineral dust and polluted mineral dust particles and their contribution to local air quality could be well distinguished. About 26.7 % of substandard days (daily averaged PM2.5 concentration larger than 75 µg m−3) in Beijing featured high atmospheric loading of coarse-mode particles in winter and springtime. In particular, during severe pollution episodes in winter, the δ values of coarse-mode particles decreased by 13 %, which implies a high possibility of dust-related heterogeneous processes in pollution formation. During dust events, δ values of particles with optical size (Dp) of 5 µm evidently decreased, with an increase of the PM2.5 ∕ PM10 ratio as well as RH, indicating the morphological changes of mineral dust. This study confirmed that high RH tends to promote water absorption processes on the dust surface as well as the coating of soluble compounds, and suggested that remote sensing techniques for aerosols may underestimate the impact of dust particles due to the complex mixing of dust and anthropogenic particles in urban areas, and the interaction between dust particles and pollutants should be considered well by the optical model.

EVALUATING PERMEABILITY AND MECHANICAL PROPERTIES OF WASTE MARBLE DUST MIX CONCRETE AND BENTONITE MIX CONCRETE

In this research attempt is made to examine Waste Marble Dust Mix (WMD) Concrete and Bentonite Mix Concrete. For physical and chemical properties of both concrete mixes, cylinders were examined in the laboratory for permeability testing, scanning electronic microscopy test, slump test, compressive strength test, and split tensile test. Cylinders were prepared in the ratio 1:2:4 with varying marble dust and bentonite content with 5% increment up to 20%. At 28 days with 10% replacement of marble dust and bentonite with cement, the permeability of WMD and Bentonite concrete were decreased by 21% and 34%. Increasing the percentage of WMD and bentonite from 10 to 20%, the MD concrete permeability was drastically increased. After crossing 10% limit it starts working as over burdening additives and allows water to flow through the cylinders, while with bentonite mix concrete by 20% replacement with cement, the permeability was further decreased up to 43%. The compressive and split strength test results of both mixes were totally different from each other. The compressive strength of WMD mix concrete decreased as the percentage of WMD was increased. At 28 days with 10% replacement, the compressive and split tensile strength were reduced by 8.9% and 2.1%. Whereas in bentonite mix, the concrete compressive and split strength were increased by 7.2% and 1.45 and were furthermore increased up to 20% replacement.

Transport, mixing and feedback of dust, biomass burning and anthropogenic pollutants in eastern Asia: a case study

Abstract. Anthropogenic fossil fuel (FF) combustion, biomass burning (BB) and desert dust are the main sources of air pollutants around the globe but are particularly intensive and important for air quality in Asia in spring. In this study, we investigate the vertical distribution, transport characteristics, source contribution and meteorological feedback of these aerosols in a unique pollution episode that occurred in eastern Asia based on various measurement data and modeling methods. In this episode, the Yangtze River Delta (YRD) in eastern China experienced persistent air pollution, dramatically changing from secondary fine particulate pollution to dust pollution in late March 2015. The Eulerian and Lagrangian models were conducted to investigate the vertical structure, transport characteristics and mechanisms of the multi-scale, multisource and multiday air pollution episode. The regional polluted continental aerosols mainly accumulated near the surface, mixed with dust aerosol downwash from the upper planetary boundary layer (PBL) and middle–lower troposphere (MLT), and further transported by large-scale cold fronts and warm conveyor belts. BB smoke from Southeast Asia was transported by westerlies around the altitude of 3 km from southern China, was further mixed with dust and FF aerosols in eastern China and experienced long-range transport over the Pacific. These pollutants could all be transported to the YRD region and cause a structure of multilayer pollution there. These pollutants could also cause significant feedback with MLT meteorology and then enhance local anthropogenic pollution. This study highlights the importance of intensive vertical measurement in eastern China and the downwind Pacific Ocean and raises the need for quantitative understanding of environmental and climate impacts of these pollution sources.

Study of the Influence of Fly Ash and Its Content in Marshall Properties of Asphalt Concrete

The study presents possible use of fly ash in asphalt concrete and also an insight on the effect of different fly ash content on Marshall Properties and Optimum Bitumen Content (OBC). Use of a VG-10 grade bitumen was done for the preparation of mix. Four fly ash content, 3%, 5%, 7% and 9% with varying bitumen contents were prepared and compared with 5% cement mix and 5% stone dust mix. Consideration of filler content in mix design is very important. At different filler contents asphalt concrete mixes behave differently. Marshall Stability of mix increase with the increase in filler content at OBC. However, stability only increase till 7% fly ash content. With more inclusion of fly ash in the mix, stability decreases. A maximum stability of 15.88 kN is observed at 7% fly ash content at 6.30% OBC. In contrast to that, mixes become less flexible when filler content is increased in mix (mixes show lower flow value). Thus, increased viscosity (as shown from increased flow value) results in increase in OBC with increase in fly ash content. Additionally, mixes with fly ash behaves superiorly when compared to other conventional mix. Fly ash mix at 7% content at OBC, though with high cost is economically feasible and superior in physical characteristics (in the case, Marshall properties) compared to other fly ash content mix and cement mix.

Mechanisms of dissolved and labile particulate iron supply to shelf waters and phytoplankton blooms off South Georgia, Southern Ocean

Abstract. The island of South Georgia is situated in the iron (Fe)-depleted Antarctic Circumpolar Current of the Southern Ocean. Iron emanating from its shelf system fuels large phytoplankton blooms downstream of the island, but the actual supply mechanisms are unclear. To address this, we present an inventory of Fe, manganese (Mn), and aluminium (Al) in shelf sediments, pore waters, and the water column in the vicinity of South Georgia, alongside data on zooplankton-mediated Fe cycling processes, and provide estimates of the relative dissolved Fe (DFe) fluxes from these sources. Seafloor sediments, modified by authigenic Fe precipitation, were the main particulate Fe source to shelf bottom waters as indicated by the similar Fe ∕ Mn and Fe ∕ Al ratios for shelf sediments and suspended particles in the water column. Less than 1 % of the total particulate Fe pool was leachable surface-adsorbed (labile) Fe and therefore potentially available to organisms. Pore waters formed the primary DFe source to shelf bottom waters, supplying 0.1–44 µmol DFe m−2 d−1. However, we estimate that only 0.41±0.26 µmol DFe m−2 d−1 was transferred to the surface mixed layer by vertical diffusive and advective mixing. Other trace metal sources to surface waters included glacial flour released by melting glaciers and via zooplankton egestion and excretion processes. On average 6.5±8.2 µmol m−2 d−1 of labile particulate Fe was supplied to the surface mixed layer via faecal pellets formed by Antarctic krill (Euphausia superba), with a further 1.1±2.2 µmol DFe m−2 d−1 released directly by the krill. The faecal pellets released by krill included seafloor-derived lithogenic and authigenic material and settled algal debris, in addition to freshly ingested suspended phytoplankton cells. The Fe requirement of the phytoplankton blooms ∼ 1250 km downstream of South Georgia was estimated as 0.33±0.11 µmol m−2 d−1, with the DFe supply by horizontal/vertical mixing, deep winter mixing, and aeolian dust estimated as ∼0.12 µmol m−2 d−1. We hypothesize that a substantial contribution of DFe was provided through recycling of biogenically stored Fe following luxury Fe uptake by phytoplankton on the Fe-rich shelf. This process would allow Fe to be retained in the surface mixed layer of waters downstream of South Georgia through continuous recycling and biological uptake, supplying the large downstream phytoplankton blooms.

From Tropospheric Folding to Khamsin and Foehn Winds: How Atmospheric Dynamics Advanced a Record-Breaking Dust Episode in Crete

A record-breaking dust episode took place in Crete on 22 March 2018. The event was characterized by surface concentrations exceeding 1 mg m−3 for a period of 4–7 h, reaching record values higher than 6 mg m−3 at the background station of Finokalia. We present here a detailed analysis of the atmospheric dynamical processes during this period, to identify the main reasons for such extreme dust advection over Crete. At the synoptic scale, the weakening of the polar vortex and the meridional transport of polar air masses at upper tropospheric layers resulted in a strong jet streak over north Africa and Central Mediterranean and corresponding tropospheric folding that brought cold stratospheric air in mid and upper troposphere. Cyclogenesis occurred at the Gulf of Sirte in Libya, resulting in strong winds over the north-east parts of Libya, enhancing particle emissions. The dust plume traveled at low altitude (0.5–3 km) along the warm conveyor belt preceding the depression cold front. This type of dusty southerly wind is commonly known as “Khamsin”. As the flow approached Crete, Foehn winds at the lee side of the island favored the downward mixing of dust towards the surface, resulting in local maxima of PM10 in Heraklion and Finokalia. The analysis is based on the combination of high-resolution WRF-Chem simulations reaching up to 1 × 1 km grid space over Crete, ground-based and satellite remote sensing of the dust plumes (PollyXT LiDAR, MSG-SEVIRI, MODIS) and detailed surface aerosol in situ measurements at urban (Heraklion, Chania, Greece) and background (Finokalia) stations in Crete.

Radiative absorption enhancement of dust mixed with anthropogenic pollution over East Asia

Abstract. The particle mixing state plays a significant yet poorly quantified role in aerosol radiative forcing, especially for the mixing of dust (mineral absorbing) and anthropogenic pollution (black carbon absorbing) over East Asia. We have investigated the absorption enhancement of mixed-type aerosols over East Asia by using the Aerosol Robotic Network observations and radiative transfer model calculations. The mixed-type aerosols exhibit significantly enhanced absorbing ability than the corresponding unmixed dust and anthropogenic aerosols, as revealed in the spectral behavior of absorbing aerosol optical depth, single scattering albedo, and imaginary refractive index. The aerosol radiative efficiencies for the dust, mixed-type, and anthropogenic aerosols are −101.0, −112.9, and −98.3 Wm-2τ-1 at the bottom of the atmosphere (BOA); −42.3, −22.5, and −39.8 Wm-2τ-1 at the top of the atmosphere (TOA); and 58.7, 90.3, and 58.5 Wm-2τ-1 in the atmosphere (ATM), respectively. The BOA cooling and ATM heating efficiencies of the mixed-type aerosols are significantly higher than those of the unmixed aerosol types over the East Asia region, resulting in atmospheric stabilization. In addition, the mixed-type aerosols correspond to a lower TOA cooling efficiency, indicating that the cooling effect by the corresponding individual aerosol components is partially counteracted. We conclude that the interaction between dust and anthropogenic pollution not only represents a viable aerosol formation pathway but also results in unfavorable dispersion conditions, both exacerbating the regional air pollution in East Asia. Our results highlight the necessity to accurately account for the mixing state of aerosols in atmospheric models over East Asia in order to better understand the formation mechanism for regional air pollution and to assess its impacts on human health, weather, and climate.

Physical and Chemical Properties of Bottom Ash and Coir Dust Mix Used as Horticultural Substrates

Physical and Chemical Properties of Bottom Ash and Coir Dust Mix Used as Horticultural Substrates

The practical benefit of Phadiatop test as the first-line in vitro allergen-specific immunoglobulin E (sIgE) screening of aeroallergens among Chinese asthmatics: a validation study.

Phadiatop test is a variant of ImmunoCAP assay that covers a mixture of common aeroallergens. Its diagnostic efficiency in Chinese population remains so far inadequate. We validated Phadiatop testing with ImmunoCAP assays in a Chinese cohort. Phadiatop test was performed for serum samples from 290 asthmatics and 92 healthy controls previously tested with "classic" ImmunoCAP for house dust mix (hx2), molds and yeasts mix (mx2), tree pollen mix (tx4) and weed mix (wx5). Phadiatop positivity was shown in 46.2% of 290 asthmatic patients. Using ImmunoCAP as the gold standard, the concordance rate was 91.7%; negative predictive value, 92.9%; and positive predictive value, 90.2%. The sensitivity of Phadiatop test was high for hx2 (98.2%), tx4 (100%) and wx5 (95.5%), but not for mx2 (78.4%). Yet the mx2 allergen-specific immunoglobulin E (sIgE) level in all missed cases was relatively low (0.35 to 0.90 kUA/L). The total Phadiatop sIgE level was correlated with the ImmunoCAP sIgE levels for all allergen mixes combined (rs =0.941, P<0.001) or each allergen mix, particularly the hx2 (rs =0.924) (all P<0.001), 0.53 kUA/L used as a cut-off would optimize the diagnostic performance of Phadiatop testing, yielding 89.4% sensitivity and 97.5% specificity in indentifying serums positive to any of these allergen mixes. Overall, Phadiatop test may efficiently detect sensitization to common aeroallergen mixes. In light of the currently rigorous administration on crude extracts for skin tests in China, using Phadiatop as the first-line test for suspected atopy can be cost-effective.

Pronounced changes in air quality, atmospheric and meteorological parameters, and strong mixing of smoke associated with a dust event over Bakersfield, California

On September 28, 2016, an intense dust storm impacted the city of Bakersfield and surrounding areas in California. The dust event coincided with smoke aerosols from the forest fire located in the northwest of Bakersfield. In California, forest fires are frequent during summer and fall seasons. The forest fire smoke plumes were subjected to large dispersion and appeared widespread. In this study, we present a detailed analysis of satellite and surface observations indicating pronounced changes in air quality, aerosol characteristics, trace gases, along the prevailing meteorological conditions over Bakersfield associated with the dust event and its interactions with the forest fire smoke. Back trajectory simulations clearly show inflow of the dust airmass from the Mojave Desert located east of Bakersfield, in contrast to the forward trajectories originating from the forest fire event located in the northwestern region, suggesting possibility of mixing of smoke and dust in the Bakersfield area. In addition, low and strong wavelength dependence of aerosol single scattering albedo also supports the observations of strong aerosol mixing of dust and smoke.