A record of atmospheric halocarbons during the twentieth century from polar firn air

Butler, J. H.; Battle, Mark; Bender, Michael L.; Montzka, S. A.; Clarke, Andrew; Saltzman, E. S.; Sucher, Cara M.; Severinghaus, Jeffrey P.; Elkins, James W.

doi:10.1038/21586

Cited by 235 publications

(236 citation statements)

References 44 publications

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“…From May 25 to May 31, 2006, we investigated GEM in the firn air at a remote location 10 km away from Summit Station, central Greenland (72.6°N, 38.5°W, 3200 m elevation). We sampled firn air using established methods (18,19,56) from one borehole at depths of 15,25,30,40,50,58,63,66,70,72,74,76,78, and 79.5 m. A 4-m long bladder was lowered into the borehole after drilling to the sampling depth and pressurized with air from the bottom of the hole, effectively sealing the hole. Two Dekabon (polyethylene/aluminum composite) lines were used to pump firn air from a space left immediately below the bladder.…”

Section: Methodsmentioning

confidence: 99%

Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s

Faïn

Ferrari

Dommergue

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Mercury (Hg) is an extremely toxic pollutant, and its biogeochemical cycle has been perturbed by anthropogenic emissions during recent centuries. In the atmosphere, gaseous elemental mercury (GEM; Hg°) is the predominant form of mercury (up to 95%). Here we report the evolution of atmospheric levels of GEM in mid-to high-northern latitudes inferred from the interstitial air of firn (perennial snowpack) at Summit, Greenland. GEM concentrations increased rapidly after World War II from Ϸ1.5 ng m ؊3 reaching a maximum of Ϸ3 ng m ؊3 around 1970 and decreased until stabilizing at Ϸ1.7 ng m ؊3 around 1995. This reconstruction reproduces real-time measurements available from the Arctic since 1995 and exhibits the same general trend observed in Europe since 1990. Anthropogenic emissions caused a two-fold rise in boreal atmospheric GEM concentrations before the 1970s, which likely contributed to higher deposition of mercury in both industrialized and remotes areas. Once deposited, this toxin becomes available for methylation and, subsequently, the contamination of ecosystems. Implementation of air pollution regulations, however, enabled a large-scale decline in atmospheric mercury levels during the 1980s. The results shown here suggest that potential increases in emissions in the coming decades could have a similar large-scale impact on atmospheric Hg levels.atmosphere ͉ Greenland ͉ past century ͉ pollution

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Section: Methodsmentioning

confidence: 99%

Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s

Faïn

Ferrari

Dommergue

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…Its atmospheric history is well established with agreement between instrumental time series measurements beginning in 1978 and industry-reported production and emission data (Walker et al, 2000), the distribution of dissolved CFC-12 in the oceans (e.g. Weiss et al, 1985), and firn air measurements (Butler et al, 1999;Sturrock et al, 2002). Its atmospheric history (ftp://ftp.cmdl.noaa.gov/hats/firnair/) indicates that the CFC-12 mixing ratio in the atmosphere was less than 1 ppt before the 1940's.…”

Section: Introductionmentioning

confidence: 64%

“…Recently, firn air and ice core studies have been used to examine the atmospheric variability of less abundant trace gases such as methyl chloride, methyl bromide, and carbonyl sulfide Butler et al, 1999;Saito et al, 2007;Saltzman et al, 2008;Sturges et al, 2001a, b;Trudinger et al, 2004;Williams et al, 2007). These measurements, which can potentially be extended to a range of low-level trace gases, allow for examination of the natural variability in atmospheric levels of these compounds as well as the influence of human activities on the trace gas composition of the atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

et al. 2010

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Abstract. In this study, we report measurements of CFC-12 (CCl 2 F 2 ) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition.

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“…The ALE, GAGE, AGAGE and CSIRO data are reported in the SIO05 gravimetric scale; the CSIRO data were placed on an approximate SIO05 scale using the average ratio of ALE to CSIRO monthly means A Note: 1 Gg (gigagram) is equivalent to one kilotonne, and 1 Mg (megagram) is equivalent to one tonne. [5] ALE HP5840A GC-ECD ( 63 Ni) packed SP2100 silicone 1978-1985 [7,11] GAGE HP5880 GC-ECD ( 63 Ni) packed SP2100 silicone 1981-1994 [8,11] AGAGE HP5890 II GC-ECD ( 63 Ni) packed SP2100 silicone 1993-present [11] Aspendale AGAGE Agilent GC 6890-MSD 5973-ADS capillary fused silica/CPSil-5 CB 2005-2009 [11,24] AGAGE Agilent GC 6890N-MSD 5973-Medusa capillary fused silica/CP-PoraBOND Q 2006-2011 [49] Antarctic firn AGAGE HP5890 II GC-ECD ( 63 Ni) packed SP2100 silicone 1936-1991 [10,11] during the ALE-CSIRO overlap period (1978)(1979)(1980)(1981)(1982). The firn data were originally reported in the SIO98 scale, [10] but are now reported in the SIO05 scale; the scales are identical for CCl 4 .…”

Section: Methodsmentioning

confidence: 99%

“…[1,6,8,12] The Antarctic firn data are consistent with no significant pre-industrial atmospheric levels of CCl 4 ; however, given the uncertainties in the inversion of the Antarctic firn data, a pre-industrial level of ,5 ppt cannot be ruled out. [10,24] The complete CCl 4 data record collected at Cape Grim is shown in Fig. 2.…”

Section: Observationsmentioning

confidence: 99%

Australian carbon tetrachloride emissions in a global context

et al. 2014

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Environmental context Carbon tetrachloride in the background atmosphere is a significant environmental concern, responsible for ~10% of observed stratospheric ozone depletion. Atmospheric concentrations of CCl4 are higher than expected from currently identified emission sources: largely residual emissions from production, transport and use. Additional sources are required to balance the expected atmospheric destruction of CCl4 and may contribute to a slower-than-expected recovery of the Antarctic ozone ‘hole’. Abstract Global (1978–2012) and Australian (1996–2011) carbon tetrachloride emissions are estimated from atmospheric observations of CCl4 using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) global network, in particular from Cape Grim, Tasmania. Global and Australian emissions are in decline in response to Montreal Protocol restrictions on CCl4 production and consumption for dispersive uses in the developed and developing world. However, atmospheric data-derived emissions are significantly larger than ‘bottom-up’ estimates from direct and indirect CCl4 production, CCl4 transportation and use. Australian CCl4 emissions are not a result of these sources, and the identification of the origin of Australian emissions may provide a clue to the origin of some of these ‘missing’ global sources.

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A record of atmospheric halocarbons during the twentieth century from polar firn air

Cited by 235 publications

References 44 publications

Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s

Polar firn air reveals large-scale impact of anthropogenic mercury emissions during the 1970s

Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

Australian carbon tetrachloride emissions in a global context

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