Review of "Refractory Black carbon (rBC) variability in a 47-year West Antarctic Snow and Firn core"

Atmospheric Black carbon (BC) strongly affects direct radiative forcing and climate, not only while suspended in the atmosphere but also after deposition onto high albedo surfaces, which are especially sensitive, because the absorption of solar radiation by deposited BC accelerate the snowpack/ice melting. In the Southern Hemisphere, the BC generated in the continents can be transported through the atmosphere from low and mid-latitudes to Antarctica, or it can be emitted in Antarctica by the anthropogenic activities developed in situ. &#160;To assess the potential origin of the BC deposited in the snow of the Antarctic, and establish a possible relationship with the human activities that are carried out there, snow samples were taken in different sites from the Antarctic peninsula during summer periods: Chilean Base O&#8217;Higgins (BO), 2014; La Paloma Glacier 2015 and 2016 (at a distance of 6 km separated from BO); close to Chilean Base Yelcho (BY), 2018 and away from Chilean Base Yelcho 2018 (at a distance of 5 km separated from BY). Shallow snow samples were collected in Whirl-Pak (Nasco) plastics bags from the top of the snowpack, in an area of 1 m2 and 5 cm thick layer, using a clean plastic shovel and disposable dust-free nitrile gloves. Sample weighed around 1500-2000 g, and they were kept always frozen (-20 &#176;C), during transport and storage, until they could be processed in the laboratory. BC concentration in the snow samples was determined by using a novel methodology recently developed, published and patent by the authors (Cereceda et al 2019, https://doi.org/10.1016/j.scitotenv.2019.133934; US 16/690,013-Nov, 2019 ). The methodology consisted of a filter-based optical method where snow samples were microwave-assisted melted, then filtered through a special filtration system able to generate a uniform BC spot on Nuclepore 47 mm polycarbonate filters (Whatman, UK). BC deposited in filters was analyzed using a SootScan&#8482;, Model OT21 Optical Transmissometer (Magee Scientific, USA), where optical transmission was compared between the sample and a reference filter at a wavelength of 880 nm. The BC mass concentration was calculated using a 5-points calibration curve, previously prepared using real diesel BC soot as standard.&#160; Results showed a BC concentration in snow of 1283.8 &#177; 1240 &#181;g kg-1. Snow from O&#8217;Higgins Base presented the highest BC concentration (3395.7 &#181;g kg-1), followed by snow from the site close to Yelcho Base (1309.2 &#181;g kg-1), snow from La Paloma Glacier 2016 (745.9 &#181;g kg-1), snow from the site away from Yelcho Base (734.5 &#181;g kg-1) and snow from La Paloma Glacier 2015 (233.6 &#181;g kg-1). BC values observed in Antarctic snow were higher than others previously reported in the literature (Cereceda et al 2019) and showed the influence that anthropic activities have in the study area, considering that the two highest values of BC concentration in snow were found at sites near the bases, which presented levels comparable to those found in snowy sites in the Andes, continental Chile (Cereceda et al 2019).

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Reduced perchlorate in West Antarctica snow during stratospheric ozone hole

Antarctic Science ◽

10.1017/s0954102016000705 ◽

2017 ◽

Vol 29 (3) ◽

pp. 292-296 ◽

Cited By ~ 4

Author(s):

T.Z. Crawford ◽

Alexandria D. Kub ◽

Kari M. Peterson ◽

Thomas S. Cox ◽

Jihong Cole-Dai

Keyword(s):

Ozone Depletion ◽

Stratospheric Ozone ◽

Stratospheric Ozone Depletion ◽

West Antarctica ◽

The West ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Apparent Correlation ◽

Antarctic Snow ◽

Perchlorate Concentration

AbstractSnowpit samples collected at the West Antarctic Ice Sheet (WAIS) Divide location in January 2013 were analysed to investigate the levels and variations of perchlorate concentrations in Antarctic snow. During 2008–12, the perchlorate concentration in WAIS Divide snow ranged between 6–180 ng l–1 and followed a seasonal cycle. The highest concentrations appeared in the autumn, and the lowest in winter and spring. No apparent correlation was observed between perchlorate and nitrate or chloride concentrations in snow. Since perchlorate is believed to form in the atmosphere when chlorine species are oxidized in reactions involving ozone, perchlorate concentrations were hypothesized to be high during the spring, based on the assumption that stratospheric ozone depletion enhances tropospheric perchlorate production. The data show that perchlorate concentrations in snow were sharply reduced during stratospheric ozone depletion events; the evidence, therefore, does not support the hypothesis. Instead, the results suggest a stratospheric origin of perchlorate in Antarctic snow.

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Sulfur isotopic measurements from a West Antarctic ice core: implications for sulfate source and transport

Annals of Glaciology ◽

10.3189/172756404781814339 ◽

2004 ◽

Vol 39 ◽

pp. 161-168 ◽

Cited By ~ 15

Author(s):

Lee E. Pruett ◽

Karl J. Kreutz ◽

Moire Wadleigh ◽

Paul A. Mayewski ◽

Andrei Kurbatov

Keyword(s):

Ice Core ◽

Sulfur Cycle ◽

South Pole ◽

Marine Aerosols ◽

West Antarctica ◽

West Antarctic ◽

Potential Source ◽

Isotopic Measurements ◽

Firn Core

AbstractMeasurements of δ34S covering the years 1935–76 and including the 1963 Agung (Indonesia) eruption were made on a West Antarctic firn core, RIDSA (78.73˚ S, 116.33˚ W; 1740ma.s.l.), and results are used to unravel potential source functions in the sulfur cycle over West Antarctica. The δ34S values of SO42– range from 3.1‰ to 9.9‰. These values are lower than those reported for central Antarctica, from near South Pole station, of 9.3–18.1‰ (Patris and others, 2000). While the Agung period is isotopically distinct at South Pole, it is not in the RIDSA dataset, suggesting differences in the source associations for the sulfur cycle between these two regions. Given the relatively large input of marine aerosols at RIDSA (determined from Na+ data and the seasonal SO42– cycle), there is likely a large marine biogenic SO42– influence. The δ34S values indicate, however, that this marine biogenic SO42–, with a well-established δ34S of 18‰, is mixing with SO42– that has extremely negative δ34S values to produce the measured isotope values in the RIDSA core. We suggest that the transport and deposition of stratospheric SO42– in West Antarctica, combined with local volcanic input, accounts for the observed variance in δ34S values.

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Refractory black carbon (rBC) variability in a 47-year West Antarctic snow and firn core

The Cryosphere ◽

10.5194/tc-14-1537-2020 ◽

2020 ◽

Vol 14 (5) ◽

pp. 1537-1554 ◽

Cited By ~ 3

Author(s):

Luciano Marquetto ◽

Susan Kaspari ◽

Jefferson Cardia Simões

Keyword(s):

South America ◽

Black Carbon ◽

Southern Hemisphere ◽

Geometric Mean ◽

Austral Summer ◽

West Antarctica ◽

Amundsen Sea ◽

Snow Albedo ◽

The Core ◽

Firn Core

Abstract. Black carbon (BC) is an important climate-forcing agent that affects snow albedo. In this work, we present a record of refractory black carbon (rBC) variability, measured from a 20 m deep snow and firn core drilled in West Antarctica (79∘55′34.6′′ S, 94∘21′13.3′′ W, 2122 m above sea level) during the 2014–2015 austral summer. This is the highest elevation rBC record from West Antarctica. The core was analyzed using the Single Particle Soot Photometer (SP2) coupled to a CETAC Marin-5 nebulizer. Results show a well-defined seasonality with geometric mean concentrations of 0.015 µg L−1 for the wet season (austral summer–fall) and 0.057 µg L−1 for the dry season (austral winter–spring). The core was dated to 47 years (1968–2015) using rBC seasonality as the main parameter, along with sodium (Na), sulfur (S) and strontium (Sr) variations. The annual rBC concentration geometric mean was 0.03 µg L−1, the lowest of all rBC cores in Antarctica referenced in this work, while the annual rBC flux was 6.25 µg m−2 a−1, the lowest flux in West Antarctica rBC records. No long-term trend was observed. Snow albedo reductions at the site due to BC were simulated using SNICAR online and found to be insignificant (−0.48 %) compared to clean snow. Fire spot inventory and BC emission estimates from the Southern Hemisphere suggest Australia and Southern Hemisphere South America as the most probable emission sources of BC to the drilling site, whereas HYSPLIT model particle transport simulations from 1968 to 2015 support Australia and New Zealand as rBC sources, with limited contributions from South America. Spectral analysis (REDFIT method) of the BC record showed cycles related to the Antarctic Oscillation (AAO) and to El Niño–Southern Oscillation (ENSO), but cycles in common with the Amundsen Sea Low (ASL) were not detected. Correlation of rBC records in Antarctica with snow accumulation, elevation and distance to the sea suggests rBC transport to East Antarctica is different from transport to West Antarctica.

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Refractory Black carbon (rBC) variability in a 47-year West Antarctic Snow and Firn core

10.5194/tc-2019-207 ◽

2019 ◽

Author(s):

Luciano Marquetto ◽

Susan Kaspari ◽

Jefferson Cardia Simões

Keyword(s):

Black Carbon ◽

Southern Hemisphere ◽

Southern Oscillation ◽

Geometric Mean ◽

Austral Summer ◽

West Antarctica ◽

Wet Season ◽

Snow Albedo ◽

The Core ◽

Firn Core

Abstract. Black carbon (BC) is an important climate-forcing agent that affects snow albedo. In this work, we present a record of refractory black carbon (rBC) variability, measured from a 20-meter deep snow and firn core drilled in West Antarctica (79°55'34.6"S, 94°21'13.3"W) during the 2014–2015 austral summer. The core was analyzed using a Single Particle Soot Photometer (SP2) coupled to a CETAC Marin-5 nebulizer. Results show a well-defined seasonality with geometric mean concentrations of 0.015 µg L−1 for the wet season (summer/fall) and 0.057 µg L−1 for the dry season (winter/spring). The core was dated to 47 years (1968–2015) using rBC seasonality as the main parameter, along with Na, S and Sr variations. The annual rBC concentration geometric mean was 0.03 µg L−1, the lowest of all rBC cores in Antarctica referenced in this work, while the annual rBC flux was 6.25 µg m−2 a−1, the lowest flux in West Antarctica records so far. No long-term trend was observed. Snow albedo changes in the site due to BC were simulated using SNICAR-online and found to be very low comparing to clean snow (−0.48 %). Fire spots inventory and BC emission estimates from the Southern Hemisphere suggest Australia and Southern Hemisphere South America as the most probable emission sources of BC to the drilling site. Spectral analysis (REDFIT method) of the BC record showed cycles related to the Antarctic Oscillation (AAO) but not to El Niño Southern Oscillation ENSO, and comparison with time series of co-registered Na record suggest BC transport to the site not to be related to the intrusion of marine air masses.

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Large scale changes in 20th century black carbon deposition to Antarctica

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-27815-2011 ◽

2011 ◽

Vol 11 (10) ◽

pp. 27815-27831 ◽

Cited By ~ 7

Author(s):

M. M. Bisiaux ◽

R. Edwards ◽

J. R. McConnell ◽

M. A. J. Curran ◽

T. D. Van Ommen ◽

...

Keyword(s):

Black Carbon ◽

Southern Hemisphere ◽

Atmospheric Chemistry ◽

Large Scale ◽

Atmospheric Transport ◽

Global Climate ◽

Ice Core ◽

Ice Sheet ◽

Antarctic Ice Sheet ◽

West Antarctic

Abstract. Refractory black carbon aerosols (rBC) emitted by biomass burning (fires) and fossil fuel combustion, affect global climate and atmospheric chemistry. In the Southern Hemisphere (SH), rBC is transported in the atmosphere from low latitudes to Antarctica and deposited to the polar ice sheet preserving a history of emissions and atmospheric transport. Here, we present two high-resolution Antarctic rBC ice core records drilled from the West Antarctic Ice Sheet divide and Law Dome on the periphery of the East Antarctic ice sheet. Separated by ~3500 km, the records span calendar years 1850–2001 and reflect the rBC distribution over the Indian and Pacific ocean sectors of the Southern Ocean. Highly correlated over the past 60 yr, the records show that coherent large-scale changes in SH rBC occurred at decadal to inter-annual time scales, notably in ENSO-like periodicities. Decadal trends in the records are similar to inventories of SH rBC emissions from grass fires and biofuels. The combined records suggest a large-scale reduction in rBC from 1950 to 1990 over the remote Southern Hemisphere.

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