Gaseous mercury distribution in the upper troposphere and lower stratosphere observed onboard the CARIBIC passenger aircraft

Šlemr, F.; Ebinghaus, Ralf; Brenninkmeijer, C. A. M.; Hermann, M.; Kock, H. H.; Martinsson, Bengt G.; Schuck, Tanja; Sprung, Detlev; Velthoven, P. van; Zahn, Andreas; Ziereis, H.

doi:10.5194/acp-9-1957-2009

Cited by 60 publications

(32 citation statements)

References 47 publications

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“…52,53 Further, modeling suggesting that GOM concentration should increase with increasing altitude 48 has been supported by observation. 53,54 Despite current debate about shortcomings in GOM measurement instrumentation, 8,9 the presence of a large tropospheric GOM reservoir as a source of Hg in precipitation is widely accepted. 3 GOM in the free troposphere readily dissolves in cloud droplets or is scavenged by raindrops.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

High Mercury Wet Deposition at a “Clean Air” Site in Puerto Rico

Shanley

Engle

Scholl

et al. 2015

Environ. Sci. Technol.

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Atmospheric mercury deposition measurements are rare in tropical latitudes. Here we report on seven years (April 2005 to April 2012, with gaps) of wet Hg deposition measurements at a tropical wet forest in the Luquillo Mountains, northeastern Puerto Rico, U.S. Despite receiving unpolluted air off the Atlantic Ocean from northeasterly trade winds, during two complete years the site averaged 27.9 μg m(-2) yr(-1) wet Hg deposition, or about 30% more than Florida and the Gulf Coast, the highest deposition areas within the U.S. These high Hg deposition rates are driven in part by high rainfall, which averaged 2855 mm yr(-1). The volume-weighted mean Hg concentration was 9.8 ng L(-1), and was highest during summer and lowest during the winter dry season. Rainout of Hg (decreasing concentration with increasing rainfall depth) was minimal. The high Hg deposition was not supported by gaseous oxidized mercury (GOM) at ground level, which remained near global background concentrations (<10 pg m(-3)). Rather, a strong positive correlation between Hg concentrations and the maximum height of rain detected within clouds (echo tops) suggests that droplets in high convective cloud tops scavenge GOM from above the mixing layer. The high wet Hg deposition at this "clean air" site suggests that other tropical areas may be hotspots for Hg deposition as well.

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Section: Environmental Science and Technologymentioning

confidence: 99%

High Mercury Wet Deposition at a “Clean Air” Site in Puerto Rico

Shanley

Engle

Scholl

et al. 2015

Environ. Sci. Technol.

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“…Since the system is the work horse for atmospheric mercury detection, its analytical performance has been well studied and a number of methodological uncertainties and limitations were identified (e.g. Swartzendruber et al, 2009;Slemr et al, 2009;Lyman et al, 2010). These include calibration nonlinearity at low concentrations, and losses due to interference of oxidants and incomplete capture of Hg 2+ .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of discrepancy between measured and modelled oxidized mercury species

et al. 2013

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Abstract. L. Zhang et al. (2012), in a recent report, compared model estimates with new observations of oxidized and particulate mercury species (Hg2+ and Hgp) in the Great Lakes region and found that the sum of Hg2+ and Hgp varied between a factor of 2 to 10 between measurements and model. They suggested too high emission inputs as Hg2+ and too fast oxidative conversion of Hg0 to Hg2+ and Hgp as possible causes. This study quantitatively explores measurement uncertainties in detail. These include sampling efficiency, composition of sample, interfering species and calibration errors. Model (Global/Regional Atmospheric Heavy Metals Model – GRAHM) sensitivity experiments are used to examine the consistency between various Hg measurements and speciation of Hg near emission sources to better understand the discrepancies between modelled and measured concentrations of Hg2+ and Hgp. We find that the ratio of Hg0, Hg2+ and Hgp in the emission inventories, measurements of surface air concentrations of oxidized Hg and measurements of wet deposition are currently inconsistent with each other in the vicinity of emission sources. Current speciation of Hg emissions suggests higher concentrations of Hg2+ in air and in precipitation near emission sources; however, measured air concentrations of Hg2+ and measured concentrations of Hg in precipitation are not found to be significantly elevated near emission sources compared to the remote regions. The averaged unbiased root mean square error (RMSE) between simulated and observed concentrations of Hg2+ is found to be reduced by 42% and for Hgp reduced by 40% for 21 North American sites investigated, when a ratio for Hg0 : Hg2+ : Hgp in the emissions is changed from 50 : 40 : 10 (as specified in the original inventories) to 90 : 8 : 2. Unbiased RMSE reductions near emissions sources in the eastern United States and Canada are found to be reduced by up to 58% for Hg2+. Significant improvement in the model simulated spatial distribution of wet deposition of mercury in North America is noticed with the modified Hg emission speciation. Measurement-related uncertainties leading to lower estimation of Hg2+ concentrations are 86%. Uncertainties yielding either to higher or lower Hg2+ concentrations are found to be 36%. Finally, anthropogenic emission uncertainties are 106% for Hg2+. Thus it appears that the identified uncertainties for model estimates related to mercury speciation near sources, uncertainties in measurement methodology and uncertainties in emissions can close the gap between modelled and observed estimates of oxidized mercury found in L. Zhang et al. (2012). Model sensitivity simulations show that the measured concentrations of oxidized mercury, in general, are too low to be consistent with measured wet deposition fluxes in North America. Better emission inventories (with respect to speciation), better techniques for measurements of oxidized species and knowledge of mercury reduction reactions in different environments (including in-plume) in all phases are needed for improving the mercury models.

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“…To find out the main contributing source to a certain air parcel during high‐CO events, chemical tracers, such as acetonitrile and CH 3 Cl for biomass burning and C 2 Cl 4 for anthropogenic (urban/industrial) emissions were used to examine the influence of these sources. For those events showing the influence of both source categories, the ratio of ΔTGM/ΔCO (total gaseous mercury), which has been found to be different within anthropogenic (higher value) and biomass/biofuel burning (lower value) plumes [ Slemr et al , 2009], was used to further classify the relative strength of both sources. Furthermore, back trajectory analysis for tracing of source regions, fire maps for fire events, and satellite cloud images for convection were also used to confirm the source region and the pathway of CO uplift from surface sources.…”

Section: Resultsmentioning

confidence: 99%

“…Because of the low temporal resolution of TGM measurements, correlations of TGM versus CO can only be investigated for 16 SCEs of longer duration. Significant correlations were found during 11 events, 7 of which had slopes >7 pg/m 3 ppb, which is characteristic of anthropogenic emissions [ Slemr et al , 2009]. On the basis of the enhancements of anthropogenic tracers, 17 of 29 SCEs were found to be influenced mainly by anthropogenic emissions.…”

Section: Resultsmentioning

confidence: 99%

“…Carbon monoxide was measured with a temporal resolution of 1 s using a modified commercial CO analyzer (Model AL 5002, Aero‐Laser, Garmisch‐Partenkirchen, Germany) based on vacuum ultraviolet fluorescence [ Brenninkmeijer et al , 2007]. The CO scale used prior to July 2010 [ Lai et al , 2010; Slemr et al , 2009] was systematically biased to lower values over the range of 0 to 250 ppbv, as was confirmed by a recent round robin laboratory intercomparison organized by NOAA‐ESRL and Global Atmosphere Watch (GAW) (WMO). The CO data reported here are now based on the NOAA‐ESRL 2004 scale and are 5.4% higher than the values we published previously.…”

Section: Methodsmentioning

confidence: 99%

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Characterization and source regions of 51 high-CO events observed during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights between south China and the Philippines, 2005–2008

Lai¹,

Baker²,

Schuck³

et al. 2011

J. Geophys. Res.

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[1] Carbon monoxide (CO) and other atmospheric trace constituents were measured from onboard an Airbus 340-600 passenger aircraft in the upper troposphere (UT) between south China and the Philippines during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights from May 2005 until March 2008. A total of 132 events having CO enhancements were observed in the UT over the region during the 81 CARIBIC flights from Frankfurt, Germany, to Manila, Philippines, with a stopover in Guangzhou, China. Among these, 51 high-CO events with enhancements more than 50 ppb above background were observed. For these events enhancements ranged from 52.7 to 221.3 ppb and persisted for 3 to 78 min (∼40 to 1200 km), indicating an influence of strong pollution from biomass/biofuel/fossil fuel burning on the trace gas composition of the UT. Back trajectory analysis shows that south China, the Indochinese Peninsula, and the Philippines/Indonesia are the main source regions of the high-CO events. The composition of air parcels originating from south China was found to be primarily influenced by anthropogenic urban/industrial emissions, while emissions from biomass/ biofuel burning contributed substantially to CO enhancements from the Indochinese Peninsula. During the Philippines/Indonesia events, air parcel composition suggests contributions from both biomass/biofuel burning and urban/industrial sources. Long-range transport of air parcels from northeast Asia and India also contributed to CO enhancements in the UT over the region. The general features of regional influence, typical cases, and the contributions of biomass/biofuel burning and anthropogenic emissions are presented and discussed to characterize the air parcels during the observed high-CO events.

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Gaseous mercury distribution in the upper troposphere and lower stratosphere observed onboard the CARIBIC passenger aircraft

Cited by 60 publications

References 47 publications

High Mercury Wet Deposition at a “Clean Air” Site in Puerto Rico

High Mercury Wet Deposition at a “Clean Air” Site in Puerto Rico

Evaluation of discrepancy between measured and modelled oxidized mercury species

Characterization and source regions of 51 high-CO events observed during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights between south China and the Philippines, 2005–2008

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