Year-round records of bulk aerosol composition over the Zhongshan Station, Coastal East Antarctica

Xu, Guang-Xin; Chen, Liqi; Zhang, Miming; Zhang, Yuanhui; Wang, Jianjun; Qiu, Lin

doi:10.1007/s11869-018-0642-9

Cited by 16 publications

(16 citation statements)

References 49 publications

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“…It can be noted that Fe and Pb had the lowest CEFs (with the median value lower than 3), with enrichment factor values decreasing in the following order: Cd > Cu > Pb ≈ Fe. According to the results, Fe may be attributable to crustal local inputs, confirming the results of previous studies carried out in the same study area [10,13,14] and in other Antarctic regions [73,74].…”

Section: Source Identificationsupporting

confidence: 90%

“…The marine biogenic activities can also contribute to the metal content in PM10. It is known that some metals (Pb, Cd, Hg) can be methylated in the ocean by polar marine According to the results, Fe may be attributable to crustal local inputs, confirming the results of previous studies carried out in the same study area [10,13,14] and in other Antarctic regions [73,74].…”

Section: Source Identificationsupporting

confidence: 89%

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Seasonal Evolution of the Chemical Composition of Atmospheric Aerosol in Terra Nova Bay (Antarctica)

et al. 2021

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Atmospheric aerosol samples were collected at Faraglione Camp, 3 km away from the Italian Mario Zucchelli Station (Terra Nova Bay, Ross Sea), from 1 December 2013 to 2 February 2014. A two-step extraction procedure was applied to characterize the soluble and insoluble components of PM10-bound metals. Samples were analyzed for Al, Fe, Cd, Cu, and Pb by square wave anodic stripping voltammetry (SWASV) and by graphite furnace atomic absorption spectrophotometer (GF-AAS). The mean atmospheric concentrations were (reported as means ± SD) Al 24 ± 3 ng m−3; Fe 23 ± 4 ng m−3; Cd 0.92 ± 0.53 pg m−3; Cu 43 ± 9 pg m−3, and Pb 16 ± 5 pg m−3. The fractionation pattern was metal-specific, with Al, Fe, and Pb mainly present in the insoluble fractions, Cd in the soluble one, and Cu equally distributed between the two fractions. The summer evolution showed overall constant behavior of both fractions for Al and Fe, while a bell-shaped trend was observed for the three trace metals. Cd and Cu showed a bell-shaped evolution involving both fractions. A seasonal increase in Pb occurred only for the insoluble fraction, while the soluble fraction remained almost constant. Sequential extraction and enrichment factors indicated a crustal origin for Al, Fe, and Pb, and additional (marine or anthropogenic) contributions for Cd and Cu. Back trajectory analysis showed a strong contribution of air masses derived from the Antarctic plateau. A potential low contribution from anthropized areas cannot be excluded. Further studies are necessary to better characterize the chemical composition of the aerosol, to discriminate between natural and anthropogenic sources, and to evaluate a quantitative source apportionment.

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Section: Source Identificationsupporting

confidence: 90%

Section: Source Identificationsupporting

confidence: 89%

Seasonal Evolution of the Chemical Composition of Atmospheric Aerosol in Terra Nova Bay (Antarctica)

et al. 2021

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“…N 2 fixation should be below detection in the winter Southern Ocean due to the cold temperatures, lowlight and low-iron conditions, and high NO − 3 concentrations (Jiang et al, 2018;Knapp et al, 2012;Kustka et al, 2003). NH + 4 aerosols are unlikely to be abundant over regions of the Southern Ocean remote from islands and coastal Antarctica, particularly in winter when NH + 4 aerosol concentrations have been shown to reach a minimum (Legrand et al, 1998;Xu et al, 2019). Moreover, the aerosols that are present over the open Southern Ocean will derive mainly from surface ocean NH 3 efflux; once re-deposited, this NH + 4 does not constitute a new input to surface waters (Altieri et al, 2021).…”

Section: Ammonium Production and Other Sources Of Ammoniummentioning

confidence: 99%

Biogeochemical controls on ammonium accumulation in the surface layer of the Southern Ocean

et al. 2022

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Abstract. The production and removal of ammonium (NH4+) are essential upper-ocean nitrogen cycle pathways, yet in the Southern Ocean where NH4+ has been observed to accumulate in surface waters, its mixed-layer cycling remains poorly understood. For surface seawater samples collected between Cape Town and the Marginal Ice Zone in winter 2017, we found that NH4+ concentrations were 5-fold higher than is typical for summer and lower north than south of the Subantarctic Front (0.01–0.26 µM versus 0.19–0.70 µM). Our observations confirm that NH4+ accumulates in the Southern Ocean's winter mixed layer, particularly in polar waters. NH4+ assimilation rates were highest near the Polar Front (12.9 ± 0.4 nM d−1) and in the Subantarctic Zone (10.0 ± 1.5 nM d−1), decreasing towards the Marginal Ice Zone (3.0 ± 0.8 nM d−1) despite the high ambient NH4+ concentrations in these southernmost waters, likely due to the low temperatures and limited light availability. By contrast, rates of NH4+ oxidation were higher south than north of the Polar Front (16.0 ± 0.8 versus 11.1 ± 0.5 nM d−1), perhaps due to the lower-light and higher-iron conditions characteristic of polar waters. NH4+ concentrations were also measured along five transects of the Southern Ocean (Subtropical Zone to Marginal Ice Zone) spanning the 2018/19 annual cycle. These measurements reveal that mixed-layer NH4+ accumulation south of the Subantarctic Front derives from sustained heterotrophic NH4+ production in late summer through winter that, in net, outpaces NH4+ removal by temperature-, light-, and iron-limited microorganisms. Our observations thus imply that the Southern Ocean becomes a biological source of CO2 to the atmosphere in autumn and winter not only because nitrate drawdown is weak but also because the ambient conditions favour net heterotrophy and NH4+ accumulation.

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“…Those that are present mainly originate from surface ocean NH 3 efflux; once redeposited, this NH₄⁺ does not constitute a new input term to surface waters (Altieri et al, 2021). Additionally, NH₄⁺ aerosol concentrations are at a minimum in winter (Legrand et al, 1998;Xu et al, 2019). NH₄⁺ deposition to the surface Southern Ocean is thus likely minimal.…”

Section: Ammonium Production and Other Inputsmentioning

confidence: 99%

Biogeochemical controls on wintertime ammonium accumulation in the surface layer of the Southern Ocean

Smith

Altieri

Mdutyana

et al. 2021

Preprint

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Abstract. The production and consumption of ammonium (NH4+) are essential upper-ocean nitrogen cycle pathways, yet in the Southern Ocean where NH4+ has been observed to accumulate in surface waters, its mixed-layer cycling remains poorly understood. For surface samples collected between Cape Town and the marginal ice zone (MIZ) in winter 2017, we found that NH4+ concentrations were five-fold higher than is typical for summer, and lower north than south of the Subantarctic Front (SAF; 0.01–0.26 µM versus 0.19–0.70 µM). Our observations confirm that NH4+ accumulates in the Southern Ocean’s winter mixed layer, particularly in polar waters. NH4+ uptake rates were highest near the Polar Front (PF; 12.9 ± 0.4 nM day−1) and in the Subantarctic Zone (10.0 ± 1.5 nM day−1), decreasing towards the MIZ (3.0 ± 0.8 nM day−1) despite high ambient NH4+ concentrations, likely due to low sea surface temperatures and light availability. By contrast, rates of NH4+ oxidation were higher south than north of the PF (16.0 ± 0.8 versus 11.1 ± 0.5 nM day−1), perhaps due to the lower light and higher iron conditions characteristic of polar waters. Augmenting our dataset with NH4+ concentration measurements spanning the 2018/2019 annual cycle reveals that mixed-layer NH4+ accumulation south of the SAF likely derives from sustained heterotrophic NH4+ production in late summer through winter that outpaces NH4+ consumption by temperature-, light, and iron-limited microorganisms. Our observations thus imply that the Southern Ocean becomes a biological source of CO2 to the atmosphere for half the year not only because nitrate drawdown is weak, but also because the ambient conditions favour net heterotrophy and NH4+ accumulation.

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Year-round records of bulk aerosol composition over the Zhongshan Station, Coastal East Antarctica

Cited by 16 publications

References 49 publications

Seasonal Evolution of the Chemical Composition of Atmospheric Aerosol in Terra Nova Bay (Antarctica)

Seasonal Evolution of the Chemical Composition of Atmospheric Aerosol in Terra Nova Bay (Antarctica)

Biogeochemical controls on ammonium accumulation in the surface layer of the Southern Ocean

Biogeochemical controls on wintertime ammonium accumulation in the surface layer of the Southern Ocean

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