scholarly journals Effects of mineral dust on global atmospheric nitrate concentrations

2015 ◽  
Vol 15 (8) ◽  
pp. 11525-11572 ◽  
Author(s):  
V. A. Karydis ◽  
A. P. Tsimpidi ◽  
A. Pozzer ◽  
M. Astitha ◽  
J. Lelieveld
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Atmospheric Chemistry ◽  
Mineral Dust ◽  
Dust Aerosol ◽  
Dust Particles ◽  
Metallic Ions ◽  
Aerosol Formation ◽  
Atmospheric Nitrate ◽  
Nitrate Aerosol

Abstract. This study provides an assessment of the chemical composition and global aerosol load of the major inorganic aerosol components and determines the effect of mineral dust on their formation, focusing on aerosol nitrate. To account for this effect, the mineral dust aerosol components (i.e., Ca2+, Mg2+, K+, Na+) and their emissions are added to the ECHAM5/MESSy Atmospheric Chemistry model (EMAC). Gas/aerosol partitioning is simulated using the ISORROPIA-II thermodynamic equilibrium model that considers the interactions of K+-Ca2+-Mg2+-NH4+-Na+-SO42−-NO3−-Cl−-H2O aerosol components. Emissions of mineral dust aerosol components (K+-Ca2+-Mg2+-Na+) are calculated online by taking into account the soil particle size distribution and chemical composition of different deserts worldwide. The presence of the metallic ions on the simulated suite of components can substantially affect the nitrate partitioning into the aerosol phase due to thermodynamic interactions. The updated model improved the nitrate predictions over remote areas and found that the fine aerosol nitrate concentration is highest over urban and industrialized areas (1–3 μg m−3), while coarse aerosol nitrate is highest close to deserts (1–4 μg m−3). The contribution of mineral dust components to nitrate formation is large in areas with high dust concentrations with impacts that can extend across southern Europe, western USA and northeastern China. The tropospheric burden of aerosol nitrate increases by 44% by considering the interactions of nitrate with mineral dust cations. The calculated global average nitrate aerosol concentration near the surface increases by 36% while the coarse and fine mode concentrations of nitrate increase by 53 and 21%, respectively. Sensitivity tests show that nitrate aerosol formation is most sensitive to the chemical composition of the emitted mineral dust, followed by the soil size distribution of dust particles, the magnitude of the mineral dust emissions, and the aerosol state assumption.

scholarly journals Effects of mineral dust on global atmospheric nitrate concentrations

2016 ◽  
Vol 16 (3) ◽  
pp. 1491-1509 ◽  
Author(s):  
V. A. Karydis ◽  
A. P. Tsimpidi ◽  
A. Pozzer ◽  
M. Astitha ◽  
J. Lelieveld
Keyword(s):  
Chemical Composition ◽  
Size Distribution ◽  
Atmospheric Chemistry ◽  
Mineral Dust ◽  
Dust Particles ◽  
Metallic Ions ◽  
Atmospheric Nitrate ◽  
Inorganic Aerosol ◽  
Aerosol State ◽  
Nitrate Aerosol

Abstract. This study assesses the chemical composition and global aerosol load of the major inorganic aerosol components, focusing on mineral dust and aerosol nitrate. The mineral dust aerosol components (i.e., Ca2+, Mg2+, K+, Na+) and their emissions are included in the ECHAM5/MESSy Atmospheric Chemistry model (EMAC). Gas/aerosol partitioning is simulated using the ISORROPIA-II thermodynamic equilibrium model that considers K+, Ca2+, Mg2+, NH4+, Na+, SO42−, NO3−, Cl−, and H2O aerosol components. Emissions of mineral dust are calculated online by taking into account the soil particle size distribution and chemical composition of different deserts worldwide. Presence of metallic ions can substantially affect the nitrate partitioning into the aerosol phase due to thermodynamic interactions. The model simulates highest fine aerosol nitrate concentration over urban and industrialized areas (1–3 µg m−3), while coarse aerosol nitrate is highest close to deserts (1–4 µg m−3). The influence of mineral dust on nitrate formation extends across southern Europe, western USA, and northeastern China. The tropospheric burden of aerosol nitrate increases by 44 % when considering interactions of nitrate with mineral dust. The calculated global average nitrate aerosol concentration near the surface increases by 36 %, while the coarse- and fine-mode concentrations of nitrate increase by 53 and 21 %, respectively. Other inorganic aerosol components are affected by reactive dust components as well (e.g., the tropospheric burden of chloride increases by 9 %, ammonium decreases by 41 %, and sulfate increases by 7 %). Sensitivity tests show that nitrate aerosol is most sensitive to the chemical composition of the emitted mineral dust, followed by the soil size distribution of dust particles, the magnitude of the mineral dust emissions, and the aerosol state assumption.

A comparative evaluation of water uptake on several mineral dust sources

2010 ◽  
Vol 7 (2) ◽  
pp. 162 ◽  
Author(s):  
Juan G. Navea ◽  
Haihan Chen ◽  
Min Huang ◽  
Gregory R. Carmichel ◽  
Vicki H. Grassian
Keyword(s):  
Chemical Composition ◽  
Relative Humidity ◽  
Dust Particle ◽  
Water Uptake ◽  
Mineral Dust ◽  
Dust Storms ◽  
Dust Aerosol ◽  
Dust Particles ◽  
Particle Interactions ◽  
Dust Sources

Environmental context. Dust particles produced from wind blown soils are of global significance as these dust particles not only impact visibility, as evident in the recent 2009 Australian dust storm, but also atmospheric chemistry, climate and biogeochemical cycles. The amount of water vapour in the atmosphere (relative humidity) can play a role in these global processes yet there are few studies and little quantitative data on water-dust particle interactions. The focus of this research is on quantifying water-dust particle interactions for several dust sources including Asia and Africa where dust storms are most prevalent. Abstract. Mineral dust aerosol provides a reactive surface in the troposphere. The reactivity of mineral dust depends on the source region as chemical composition and mineralogy of the aerosol affects its interaction with atmospheric gases. Furthermore, the impact of mineral dust aerosol in atmospheric processes and climate is a function of relative humidity. In this study, we have investigated water uptake of complex dust samples. In particular, water uptake as a function of relative humidity has been measured on three different dust sources that have been characterised using a variety of bulk and surface techniques. For these well-characterised dust samples, it is shown that although there are variations in chemical composition and mineralogy, on a per mass basis, water uptake capacities for the three dusts are very similar and are comparable to single component clay samples. These results suggest that the measured uptake of water of these bulk samples is dominated by the clay component.

scholarly journals Measurement of scattering and absorption properties of dust aerosol in a Gobi farmland region of northwest China — a potential anthropogenic influence

2017 ◽  
Author(s):  
Jianrong Bi ◽  
Jianping Huang ◽  
Jinsen Shi ◽  
Zhiyuan Hu ◽  
Tian Zhou ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Source Region ◽  
Inversion Layer ◽  
Vertical Mixing ◽  
Northwest China ◽  
Single Scattering ◽  
Dust Aerosol ◽  
Dust Particles ◽  
Valley Wind ◽  
Average Mass

Abstract. We conducted a comprehensive field campaign on exploring the optical characteristics of mineral dust in Dunhuang farmland nearby the Gobi deserts of northwest China during spring of 2012. The day-to-day and diurnal variations of dust aerosol showed prominent features throughout the experiment, primarily attributable to frequent dust events and local anthropogenic emissions. The overall average mass concentration of the particulate matter with an aerodynamic diameter less than 10 μm (PM10), light scattering coefficient (σsp,670), absorption coefficient (σap,670), and single-scattering albedo (SSA670) were 113±169 μgm-3, 53.3 ± 74.8 Mm-1,  3.2± 2.4 Mm-1, and 0.913 ± 0.05, which were comparable to the background levels in southern United States, but smaller than that in the eastern and other northwestern China. The anthropogenic dust produced by agricultural cultivations (e.g., land planning, plowing, and disking) exerted a significant superimposed effect on high dust concentrations in Dunhuang farmland prior to the growing season (i.e., from 1 April to 10 May). Strong south valley wind and vertical mixing in daytime scavenged the pollution and weak northeast mountain wind and stable inversion layer at night favorably accumulated the air pollutants near the surface. In the afternoon (13:00–18:00 LT), mean SSA670 was 0.945 ± 0.04 that was predominant by dust particles, whereas finer particles and lower SSA670 values (~ 0.90–0.92) were measured at night, suggesting the potential influence by the mixed dust-pollutants. During a typical biomass burning event on 4 April 2012, σap,670 changed from ~ 2.0 Mm-1 to 4.75 Mm-1 and SSA670 changed from ~ 0.90 to ~ 0.83, implying remarkable modification of aerosol absorptive properties induced by human activities. The findings of this study would help to advance an in-depth understanding of the interaction among dust aerosol, atmospheric chemistry, and climate change in desert source region.

scholarly journals Hygroscopicity of Different Types of Aerosol Particles: Case Studies Using Multi-Instrument Data in Megacity Beijing, China

2020 ◽  
Vol 12 (5) ◽  
pp. 785 ◽  
Author(s):  
Tong Wu ◽  
Zhanqing Li ◽  
Jun Chen ◽  
Yuying Wang ◽  
Hao Wu ◽  
...  
Keyword(s):  
Enhancement Factor ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Dust Aerosol ◽  
Dust Particles ◽  
Chemical Components ◽  
Hygroscopic Growth ◽  
Microphysical Properties ◽  
Fine Mode ◽  
Fine Mode Aerosol

Water uptake by aerosol particles alters its light-scattering characteristics significantly. However, the hygroscopicities of different aerosol particles are not the same due to their different chemical and physical properties. Such differences are explored by making use of extensive measurements concerning aerosol optical and microphysical properties made during a field experiment from December 2018 to March 2019 in Beijing. The aerosol hygroscopic growth was captured by the aerosol optical characteristics obtained from micropulse lidar, aerosol chemical composition, and aerosol particle size distribution information from ground monitoring, together with conventional meteorological measurements. Aerosol hygroscopicity behaves rather distinctly for mineral dust coarse-mode aerosol (Case I) and non-dust fine-mode aerosol (Case II) in terms of the hygroscopic enhancement factor, f β ( R H , λ 532 ) , calculated for the same humidity range. The two types of aerosols were identified by applying the polarization lidar photometer networking method (POLIPHON). The hygroscopicity for non-dust aerosol was much higher than that for dust conditions with the f β ( R H , λ 532 ) being around 1.4 and 3.1, respectively, at the relative humidity of 86% for the two cases identified in this study. To study the effect of dust particles on the hygroscopicity of the overall atmospheric aerosol, the two types of aerosols were identified and separated by applying the polarization lidar photometer networking method in Case I. The hygroscopic enhancement factor of separated non-dust fine-mode particles in Case I had been significantly strengthened, getting closer to that of the total aerosol in Case II. These results were verified by the hygroscopicity parameter, κ (Case I non-dust particles: 0.357 ± 0.024; Case II total: 0.344 ± 0.026), based on the chemical components obtained by an aerosol chemical speciation instrument, both of which showed strong hygroscopicity. It was found that non-dust fine-mode aerosol contributes more during hygroscopic growth and that non-hygroscopic mineral dust aerosol may reduce the total hygroscopicity per unit volume in Beijing.

scholarly journals Heterogeneous reactions of mineral dust aerosol: implications for tropospheric oxidation capacity

2017 ◽  
Author(s):  
Mingjin Tang ◽  
Xin Huang ◽  
Keding Lu ◽  
Maofa Ge ◽  
Yongjie Li ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Dust Aerosol ◽  
Heterogeneous Reactions ◽  
Dust Particles ◽  
Laboratory Studies ◽  
Research Strategies ◽  
Aerosol Composition ◽  
Oxidation Capacity ◽  
Open Questions ◽  
Modelling Studies

Abstract. Heterogeneous reactions of mineral dust aerosol with trace gases in the atmosphere could directly and indirectly affect tropospheric oxidation capacity, in addition to aerosol composition and physicochemical properties. In this article we provide a comprehensive and critical review of laboratory studies of heterogeneous uptake of OH, NO3, O3, and their directly related species as well (including HO2, H2O2, HCHO, HONO, and N2O5) by mineral dust particles. Atmospheric importance of heterogeneous uptake as sinks for these species are assessed (i) by comparing their lifetimes with respect to heterogeneous reactions with mineral dust to lifetimes with respect to other major loss processes and (ii) by discussing relevant field and modelling studies. We have also outlined major open questions and challenges in laboratory studies of heterogeneous uptake by mineral dust and discussed research strategies to address them in order to better understand the effects of heterogeneous reactions with mineral dust on tropospheric oxidation capacity.

scholarly journals Measurement of scattering and absorption properties of dust aerosol in a Gobi farmland region of northwestern China – a potential anthropogenic influence

2017 ◽  
Vol 17 (12) ◽  
pp. 7775-7792 ◽  
Author(s):  
Jianrong Bi ◽  
Jianping Huang ◽  
Jinsen Shi ◽  
Zhiyuan Hu ◽  
Tian Zhou ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Source Region ◽  
Inversion Layer ◽  
Vertical Mixing ◽  
Northwest China ◽  
Dust Aerosol ◽  
Dust Particles ◽  
Gobi Desert ◽  
Valley Wind ◽  
Average Mass

Abstract. We conducted a comprehensive field campaign to explore the optical characteristics of mineral dust in Dunhuang farmland near the Gobi Desert of northwest China during spring of 2012. The day-to-day and diurnal variations of dust aerosol showed prominent features throughout the experiment, primarily attributable to frequent dust events and local anthropogenic emissions. The overall average mass concentrations of the particulate matter with an aerodynamic diameter less than 10 µm (PM10), light scattering coefficient (σsp, 670), absorption coefficient (σap, 670), and single-scattering albedo (SSA670) were 113 ± 169 µg m−3, 53.3 ± 74.8 Mm−1, 3.2 ± 2.4 Mm−1, and 0.913 ± 0.05, respectively, which were comparable to the background levels in the southern United States but smaller than those in the eastern and other northwestern Chinese cities. The anthropogenic dust produced by agricultural cultivations (e.g., land planning, plowing, and disking) exerted a significant superimposed effect on high dust concentrations in Dunhuang farmland prior to the growing season (i.e., from 1 April to 10 May). Strong south valley wind and vertical mixing in daytime scavenged the pollution, and the weak northeast mountain wind and stable inversion layer at night favorably accumulated the air pollutants near the surface. In the afternoon (13:00–18:00 LT, local time), mean SSA670 was 0.945 ± 0.04 predominantly from dust particles, whereas finer particles and lower SSA670 values ( ∼  0.90–0.92) were measured at night, suggesting the potential influence by the mixed dust pollutants. During a typical biomass burning event on 4 April 2012, σap, 670 increased from  ∼  2.0 to 4.75 Mm−1 and SSA670 changed from  ∼  0.90 to  ∼  0.83, implying remarkable modification of aerosol absorptive properties induced by human activities. The findings of this study would help to advance an in-depth understanding of the interaction among dust aerosol, atmospheric chemistry, and climate change in a desert source region.

scholarly journals Influence of measurement uncertainties on soluble aerosol iron over the oceans

2015 ◽  
Vol 12 (17) ◽  
pp. 14377-14400 ◽  
Author(s):  
N. Meskhidze ◽  
M. S. Johnson ◽  
D. Hurley ◽  
K. Dawson
Keyword(s):  
Transport Model ◽  
Mineral Dust ◽  
Operational Definition ◽  
Dust Aerosol ◽  
Global Ocean ◽  
Dust Particles ◽  
Chemical Transport Model ◽  
Water Leaching ◽  
Wide Range ◽  
Flow Through

Abstract. The atmospheric supply of dust iron (Fe) plays a crucial role in the Earth's biogeochemical cycle and is of specific importance as a micronutrient in the marine environment. Observations show several orders of magnitude variability in the fractional solubility of Fe in dust aerosols, making it hard to assess the role of mineral dust for global ocean biogeochemical Fe cycle. In this study we compare the operational solubility of dust aerosol Fe associated with one of the flow-through leaching protocols to the results of the global 3-D chemical transport model GEOS-Chem. In the protocol aerosol Fe is defined soluble by first deionized water leaching of mineral dust through a 0.45 μm pore size membrane followed by acidification and storage of the leachate over a long period of time prior to the analysis. To assess the concentrations of soluble Fe inferred by this flow-through leaching protocol we are using in situ measurements of dust size distribution with the prescribed of 50 % fractional solubility of Fe in less than 0.45 μm sized dust particles collected in the leachate. In the model, the fractional solubility of Fe is either explicitly calculated using complex dust Fe dissolution module, or prescribed to be 1 and 4 %. Calculations show that the fractional solubility of Fe derived through the flow-through leaching is typically higher compared to the model results. The largest differences (>30 %) are predicted to occur farther away from the dust source regions, over the areas where sub-0.45 μm sized mineral dust particles contribute a larger fraction of the total dust mass. This study suggests that inconsistences in the operational definition of soluble Fe could contribute to the wide range of the fractional solubility of dust aerosol Fe reported in the literature.

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