Browsing by Author "Edwards, R"

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    Aerosol iron solubility: comparison between the Australian subtropics and Southern ocean
    (Bureau of Meteorology and CSIRO Oceans and Atmosphere Flagship, 2014-11) Winton, H; Edwards, R; Bowie, A; Chambers, SD; Keywood, MD; Werczynski, S; Williams, AG
    Past changes in the atmospheric deposition of soluble, or bioavailable, trace metals to high nutrient low chlorophyll (HNLC) and nitrogen replete tropical waters have been shown to modulate primary production, atmospheric CO2, and global climate. The deposition of soluble trace metals can also trigger toxic algal blooms, which impact Australia’s fisheries and coral reefs. An understanding of the sources (e.g. mineral dust and biomass emissions) and geochemistry of soluble trace metals in atmospheric aerosols is critical for determining the impact of trace metal deposition on ocean fertility in the past and the future. However, to date no trace metal solubility data exists for biomass emissions from Australian fires and there are very few estimates of soluble trace metal aerosols entering the Southern Ocean. Trace metal clean aerosols were collected during the early‐late dry season experiment at Gunn Point, Northern Territory to investigate the trace metal aerosol solubility associated with biomass burning. Previous studies have suggested that mineral dust is the dominant source of trace metal aerosol. However, mineral dust is relatively insoluble and a significant fraction of soluble trace metals in the atmosphere could originate from biomass burning rather than mineral dust. Here we use the combination of soluble aerosol chemistry, back trajectories and diurnal and advective radon components to identify trace metal source regions throughout the campaign duration. We compare aerosol iron solubility at Gunn Point in the subtropics, where biomass burning can dominate the aerosol load in the dry season, to iron solubility in baseline air at Cape Grim which is representative of the Southern Hemisphere background. In doing this we highlight the importance of aerosol source at different latitudes for the solubility and bioavailability of trace metals.
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    Characterization of insoluble nanoparticles in Antarctic ice cores
    (American Geophysical Union, 2013-12-09) Ellis, A; Edwards, R; van Riessen, A; Saunders, M; Smith, AM; Curran, MAJ; Goodwin, ID; Feiteng, W
    Insoluble nanoparticles in the form of aerosols have significant effects on climate and biogeochemical cycles. Records of these aerosols are essential for understanding paleoclimate forcing and future climate change. These particles and their precursors are emitted to the atmosphere from a variety of primary and secondary sources including biomass burning as well as biogenic, anthropogenic, volcanic, extraterrestrial, and terrestrial mineral emissions. While a large body of research exists with respect to mineral dust particles (on the micrometer scale) derived from ice and sediment cores, very little is known with regards to the history of insoluble particles on the nano scale. Ice core records are the only reliable way to study the past history of these particles. Here, we will present new data regarding the physical and chemical properties of nanoparticles found in ice cores from East Antarctica.
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    Characterization of insoluble nanoparticles in ice cores from Law Dome, East Antarctica
    (Department of Environment Australian Antartic Division, 2013-06-24) Ellis, A; Edwards, R; van Riessen, A; Smith, AM; Curran, MAJ; Goodwin, ID; Feiteng, W
    Insoluble nanoparticles, in the form of aerosols, have significant affects on climate and biogeochemical cycles. Records of these aerosols are essential for understanding paleoclimate forcing and future climate change. While a large body of research exists with respect to mineral dust particles (micron scale) derived from ice cores and sediment cores, very little is known with regards to the history of insoluble nanoparticles. These particles and their precursors are emitted to the atmosphere from a variety of primary and secondary sources including biomass burning, biogenic, anthropogenic, volcanic, and terrestrial mineral emissions. Ice core records are the only reliable way to study the past history of these particles. Here, we will present new data with regards to the physical and chemical properties of these particles as found in the Law Dome ice core, DSS0506 from East Antarctica.
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    Characterizing black carbon in rain and ice cores using coupled tangential flow filtration and transmission electron microscopy
    (European Geosciences Union, 2015-01-01) Ellis, A; Edwards, R; Saunders, M; Chakrabarty, RK; Subramanian, R; van Riessen, A; Smith, AM; Lambrinidis, D; Nunes, LJ; Vallelonga, P; Goodwin, ID; Moy, AD; Curran, MAJ; van Ommen, TD
    Antarctic ice cores have been used to study the history of black carbon (BC), but little is known with regards to the physical and chemical characteristics of these particles in the remote atmosphere. Characterization remains limited by ultra-trace concentrations in ice core samples and the lack of adequate methods to isolate the particles unaltered from the melt water. To investigate the physical and chemical characteristics of these particles, we have developed a tangential flow filtration (TFF) method combined with transmission electron microscopy (TEM). Tests using ultrapure water and polystyrene latex particle standards resulted in excellent blanks and significant particle recovery. This approach has been applied to melt water from Antarctic ice cores as well as tropical rain from Darwin, Australia with successful results: TEM analysis revealed a variety of BC particle morphologies, insoluble coatings, and the attachment of BC to mineral dust particles. The TFF-based concentration of these particles has proven to give excellent results for TEM studies of BC particles in Antarctic ice cores and can be used for future studies of insoluble aerosols in rainwater and ice core samples. © Author(s)
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    Dating Antarctic ice cores using high-temporal resolution black carbon records
    (Antarctic Climate and Ecosystems Cooperative Research Centre, 2016-03-07) Edwards, R; Vallelonga, P; McConnell, JR; Bertler, NAN; Curran, MAJ; Sigil, M; Fudge, TJ; Anschuetz, H; Neff, PD; Emanuelsson, D; Bisiaux, M; Goodwin, D; Smith, AM; Taylor, KC; Moy, AD; Fetieng, W; Ellis, A
    Black carbon aerosols (BC) emitted by fires in the Southern Hemisphere (SH) are transported to Antarctica and preserved in the Antarctic ice sheet. Recent efforts to develop ice core records of BC deposition to Antarctica show variability in BC over a broad range of time scales. The ~ monthly-resolution BC record from the WAIS divide deep ice core displayed strong seasonal variability in modern sections of the record consistent with the timing of SH biomass burning. The record was subsequently used as an annual layer dating proxy in conjunction with other chemical species. If the emissions and transport of BC to Antarctica are stable over long periods of time it may be useful as an annual layer proxy at sites other than WAIS. To date, a rigorous comparison of Antarctic ice core BC seasonality from different locations have not been conducted. Here we present a comparison of BC ice core data from the top sections of the WAIS divide deep core, the Roosevelt Island RICE core, and the Law Dome DSS1213 core. The RICE and Law Dome sites are separated from WAIS by large distances and experience different atmospheric circulation and climate regimes. A detailed description of the data uncertainties and its use in annual layer counting will be discussed.
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    Individual particle morphology, coatings, and impurities of black carbon aerosols in Antarctic ice and tropical rainfall
    (John Wiley & Sons, Inc, 2016-11-04) Ellis, A; Edwards, R; Saunders, M; Chakrabarty, RK; Subramanian, R; Timms, NE; van Riessen, A; Smith, AM; Lambrindis, D; Nunes, LJ; Vallelonga, P; Goodwin, ID; Moy, AD; Curran, MAJ; van Ommen, TD
    Black carbon (BC) aerosols are a large source of climate warming, impact atmospheric chemistry, and are implicated in large-scale changes in atmospheric circulation. Inventories of BC emissions suggest significant changes in the global BC aerosol distribution due to human activity. However, little is known regarding BC's atmospheric distribution or aged particle characteristics before the twentieth century. Here we investigate the prevalence and structural properties of BC particles in Antarctic ice cores from 1759, 1838, and 1930 Common Era (C.E.) using transmission electron microscopy and energy-dispersive X-ray spectroscopy. The study revealed an unexpected diversity in particle morphology, insoluble coatings, and association with metals. In addition to conventionally occurring BC aggregates, we observed single BC monomers, complex aggregates with internally, and externally mixed metal and mineral impurities, tar balls, and organonitrogen coatings. The results of the study show BC particles in the remote Antarctic atmosphere exhibit complexity that is unaccounted for in atmospheric models of BC. ©2016. American Geophysical Union.