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Atmospheric Chemistry, Measurements, and Models
Published in Winston Chow, Katherine K. Connor, Peter Mueller, Ronald Wyzga, Donald Porcella, Leonard Levin, Ramsay Chang, Managing Hazardous Air Pollutants, 2020
Peter W. Sage, Peter K. Mueller
Although we are unable to compare the relative rates of HCl and chloride emissions in the U.S. from human activities vs. natural phenomena because information is not available on sea-salt aerosol fluxes being carried over the continent, the available information does permit an order-of-magnitude comparison on global scale. Global HCl and chloride emissions in Table 3 are taken from NRC6 with the following additional assumptions: 90% of sea-salt aerosol, which is produced by breaking of waves in the oceans, is deposited back into the oceans. The remaining 10% is carried over to continental atmospheres.24–26Since approximately one fourth of global coal combustion takes place in the U.S. and since coal combustion accounts for 90% of all HCl and chloride emissions from fuel combustion and manufacturing activities in the U.S., we assumed that global HCl emissions from human activities are four times the U.S. emission.
Fundamentals of Ocean Optics
Published in Victor Raizer, Optical Remote Sensing of Ocean Hydrodynamics, 2019
The third problem worthy our attention is definition of effective electromagnetic parameters of a random scattering media. It is related to the multiple scattering problems. Here we are concerned with effective wave number, Keff, and the effective complex refraction index, neff, that can be used for modeling wave propagation through the scattering volume of spherical particles. Typical environmental examples are fog, clouds, or dense sea salt aerosol. In this case, a stochastic scattering environment is considered as a continuous macroscopic turbulent medium with the average properties of randomly fluctuating fields. This is a classical topic, with a large literature and we refer the reader to well-known books (van de Hulst 1981; Ishimaru 1991; Tsang and Kong 2001; Tsang et al. 2000).
Monitoring of volcanic eruptions: An example of the application of optoelectronics instrumentation in atmospheric science
Published in P. Dakin John, G. W. Brown Robert, Handbook of Optoelectronics, 2017
The measurement bin voltage levels are calculated assuming totally scattering spherical particles with a refractive index of 1.59 as the physical calibration of the spectrometer is usually performed using polystyrene latex spheres (PSL), particles commercially produced to National Institute of Standards and Technology traceability size standards and users also regularly check the instrument calibration using the same particles with any drift corrected by postprocessing of the data. The composition of atmospheric aerosol is however highly variable (Pruppacher and Klett 1997) and hence so are the refractive indices. For example, the refractive index of sea salt at 633 nm is 1.49–1 × 10−7i, while that of soot at 633 nm is 1.75–0.43i (Shettle and Fenn 1979)—the larger complex part of the soot refractive index indicates that soot aerosol is much less efficient at scattering light than sea salt aerosol; in other words, soot is a good absorber. In the situation where there are two particles (one of sea salt and one of soot) of the same geometric size and light is scattered, the voltage of the resultant signal in the spectrometer will be less for the soot particle than for the sea salt particle. This can result in particles being incorrectly sized when the signal is compared to the bin boundary theoretical voltage values. This introduces a source of error into the measurements from optical aerosol spectrometers, but recalibration and data postprocessing, taking into account the approximate aerosol composition, is employed routinely to compensate for this.
A review on the heterogeneous oxidation of SO2 on solid atmospheric particles: Implications for sulfate formation in haze chemistry
Published in Critical Reviews in Environmental Science and Technology, 2023
Qingxin Ma, Chunyan Zhang, Chang Liu, Guangzhi He, Peng Zhang, Hao Li, Biwu Chu, Hong He
Sea salt aerosol, which is mainly derived from wave spray and bubble evaporation, is the dominant aerosol species by mass above the oceans (Gieré & Querol, 2010). The heterogeneous reaction process on sea salt has attracted much attention because it can turn halogen elements in sea salt into more-active halogen-containing species (Finlayson-Pitts, 2003; Rossi, 2003). Field observations show that there are secondary sources of sulfate in sea salt aerosols besides direct emission from the ocean, which is mainly attributed to the aqueous oxidation of SO2 in deliquesced sea salt aerosol by dissolved oxidants to form S(VI) species in the marine boundary layer (Sievering et al., 1992). It was found that the reactions of SO2 with dry NaCl, MgCl2•6H2O, and synthetic sea salt (SSS) do not produce sulfate (Gebel et al., 2000; Li et al., 2007). However, Laskin et al. (2003) demonstrated that replacement of Cl in deliquesced NaCl by •OH radicals contributes to modulating the pH due to acid formation on particles and leads to an increase in the uptake and oxidation of SO2 to sulfate on sea-salt particles.
Primary sources control the variability of aerosol optical properties in the Antarctic Peninsula
Published in Tellus B: Chemical and Physical Meteorology, 2018
Eija Asmi, Kimmo Neitola, Kimmo Teinilä, Edith Rodriguez, Aki Virkkula, John Backman, Matthew Bloss, Jesse Jokela, Heikki Lihavainen, Gerrit de Leeuw, Jussi Paatero, Veijo Aaltonen, Miguel Mei, Gonzalo Gambarte, Gustavo Copes, Marco Albertini, Germán Pérez Fogwill, Jonathan Ferrara, María Elena Barlasina, Ricardo Sánchez
The marine sea salt aerosol, by nature, is highly scattering and facilitates cloud formation as it contains high quantities of potentially good CCN (Murphy et al., 1998). These are particles with favourable size and hygroscopic properties, able to form cloud droplets at low supersaturations and have been observed to be abundant in Arctic and Antarctic marine environments (e.g. Asmi et al., 2010; Zieger et al., 2010). In Antarctica, the sea salt fraction of the total aerosol is dominant especially at the coastal sites with mass concentrations extending from some hundreds of ng m up to several g m and further increasing towards the Southern Ocean (Artaxo and Rabello, 1992; Wagenbach et al., 1998; Virkkula et al., 2006; Weller and Lampert, 2008a; Teinilä et al., 2014). Fresh sea salt is dominated by the coarse mode aerosol particles while aerosol ageing during long-range transport increases the concentrations in the sub-micron range (Teinilä et al., 2014). Towards the inland of the Antarctica, sea salt concentration decreases drastically (Teinilä et al., 2000; Virkkula et al., 2006). In Antarctic high plateaus and at the South Pole, sea salt concentration reaches its maximum in winter (Bodhaine et al., 1986; Jourdain et al., 2008) when passage of marine sea salt rich aerosol to inland is facilitated by the intensified atmospheric circulation and winter cyclonic storms (Bodhaine et al., 1986; Ito, 1989; Kaspari et al., 2005).
Anthropogenic fine aerosols dominate the wintertime regime over the northern Indian Ocean
Published in Tellus B: Chemical and Physical Meteorology, 2018
Krishnakant Budhavant, Srinivas Bikkina, August Andersson, Eija Asmi, John Backman, Jutta Kesti, H. Zahid, S. K. Satheesh, Örjan Gustafsson
The chemical characterization of aerosol particles is informative of their sources and transformation. PM2.5 and PM10 were characterized in terms of major cations (NH4+, Na+, K+, Mg2+ and Ca2+) and major anions (Cl−, NO3− and SO42−) for the six-month sampling period (Fig. 5). Sulphate and ammonia dominate the PM2.5 mass, indicating strong anthropogenic sources for the ambient fine aerosol over the N. Indian Ocean. In the fine mode, SO42- (20%) showed the highest concentration followed by NH4+ (6%), Na+ (5%), K+ (2%), Cl− (1%), Mg2+ (1%); NO3− and Ca2+ were present in smaller amounts. In contrast, for the coarse fraction, Na+ (28%) showed the highest concentration followed by Cl− (17%), NO3− (4%), Mg2+ (3%), Ca2+ (2%), K+ (2%) and NH4+ (negligible amount). These observations clearly showed that marine components like Na+, Cl− and Mg2+ were dominant in coarse mode (48%) while their contribution was much less in the fine mode (7%). The major fraction of sea salt aerosols is generally found in the coarse size range (Heintzenberg et al., 1981; Porter and Clarke, 1997; Budhavant et al., 2016). The main source of sea salt aerosol over the open ocean is sea spray droplets (Blanchard and Woodcock, 1980; Martensson et al., 2003). In fact, the slope of the linear regression analysis of Na+ versus Mg2+ (R2 = 0.99; slope = 0.12) in PM10 is consistent with that typically observed for sea salt aerosols (Mg2+/Na+ ratio in Seawater: 0.12).