Global Distribution of Tetrachloroethene in the Troposphere: Measurements and Modeling

Wiedmann, Thomas; Guethner, Brigitte.; Class, Thomas J.; Ballschmiter, Karlheinz

doi:10.1021/es00062a016

Cited by 42 publications

(20 citation statements)

References 45 publications

(44 reference statements)

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“…Average measurements of C 2 Cl 4 in the remote marine boundary layer in 1989 were 13 ± 7 ppt in the NH and 2.7 ± 0.4 in the SH [ Koppmann et al , 1993]. These values are similar to other measurements (21 ± 5 ppt from 30 to 90°N, 7 ± 3 from 0 to 30°N, and 2.2 ± 0.5 in the SH [ Wiedmann et al , 1994]; 16 ± 7 ppt over the North Atlantic [ Blake et al , 1996a]). Tetrachloroethene exhibits a strong interhemispheric gradient [ Wang et al , 1995; Rudolph et al , 1996] with an estimated tropospheric mixing ratio of 5–15 ppt in the NH and 0.7–1.5 ppt in the SH [ Ko and Poulet , 2003].…”

Section: Introductionsupporting

confidence: 80%

“…The AGAGE measurements at Mace Head are approximately 25% larger than the Dimmer et al [2001] measurements in the Arctic in August/September, 1997 and in the North Atlantic in April/May, 1998 if the McCulloch et al [1999] emissions are used. The currently observed AGAGE C 2 Cl 4 mixing ratios are lower than those reported by Wiedmann et al [1994] for 1982–1989 ( McCulloch et al [1999] do not provide emission estimates before 1988) and Blake et al [1996a].…”

Section: Box Model Calculationscontrasting

confidence: 62%

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Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene from the AGAGE observations at Mace Head, Ireland, and Cape Grim, Tasmania

et al. 2006

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In situ observations (every 4 hours) of dichloromethane (CH2Cl2) from April 1995 to December 2004 and trichloroethene (C2HCl3) and tetrachloroethene (C2Cl4) from September 2000 to December 2004 are reported for the Advanced Global Atmospheric Gases Experiment (AGAGE) station at Mace Head, Ireland. At a second AGAGE station at Cape Grim, Tasmania, CH2Cl2 and C2Cl4 data collection commenced in 1998 and 2000, respectively. C2HCl3 is below the limit of detection at Cape Grim except during pollution episodes. At Mace Head CH2Cl2 shows a downward trend from 1995 to 2004 of 0.7 ± 0.2 ppt yr−1 (ppt: expressed as dry mole fractions in 1012), although from 1998 to 2004 the decrease has been only 0.3 ± 0.1ppt yr−1. Conversely, there has been a small but significant growth of 0.05 ± 0.01 ppt yr−1 in CH2Cl2 at Cape Grim. The time series for C2HCl3 and C2Cl4 are relatively short for accurate trend analyses; however, we observe a small but significant decline in C2Cl4 (0.18 ± 0.05 ppt yr−1) at Mace Head. European emissions inferred from AGAGE measurements are compared to recent estimates from industry data and show general agreement for C2HCl3. Emissions estimated from observations are lower than industry emission estimates for C2Cl4 and much lower in the case of CH2Cl2. A study of wildfires in Tasmania, uncontaminated by urban emissions, suggests that the biomass burning source of CH2Cl2 may have been previously overestimated. All three solvents have distinct annual cycles, with the phases and amplitudes reflecting their different chemical reactivity with OH as the primary sink.

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Section: Introductionsupporting

confidence: 80%

Section: Box Model Calculationscontrasting

confidence: 62%

Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene from the AGAGE observations at Mace Head, Ireland, and Cape Grim, Tasmania

et al. 2006

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“…Tetrachloroethene shows a three-step decrease in the global mixing ratios in the lower troposphere (Wiedmann et al, 1994). A first decrease is observed when going from continental air to marine air of the Northern hemisphere.…”

Section: Characterization Of the Age Of Air Massesmentioning

confidence: 97%

Levels and pattern of volatile organic nitrates and halocarbons in the air at Neumayer Station (70°S), Antarctic

et al. 2002

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Levels and patterns of C1-C4/C9 organic nitrates were measured for the first time in Antarctica. The sampling was done by adsorptive enrichment on Tenax TA followed by thermodesorption cold-trap high resolution capillary gas chromatography with electron capture detection. 2-70 l air on-column have been analyzed this way. C1-C9 alkyl mononitrates, C2-C4 alkyl dinitrates, C2-C4 hydroxy alkyl nitrates, and halocarbons could be identified in air samples collected near the German Neumayer Research Station, Antarctica, in February 1999. Volatile biogenic and anthropogenic halocarbons were used to assess the origin of the air parcels analyzed. The average concentration measured for P C2-C6 alkyl nitrates was in the range of 9:2 AE 1:8 ppt(v), while the sum of the mixing ratios of six C2-C4 hydroxy alkyl nitrates was in the range of 1:1 AE 0:2 ppt(v). Moreover, C2-C4 alkyl dinitrates were found at levels near the detection limit of 0.1-0.5 ppt(v). The concentrations of organic nitrates found in Antarctic air represent ultimate baseline levels due to chemical and physical loss processes during long-range transport in the air. The South Atlantic and the Antarctic Ocean as a general secondary source for organic nitrates in terms of an air/sea exchange equilibrium has to be evaluated yet, but it seems logical. Our results confirm the common assumption that there are no biogenic marine sources of C2-C9 organonitrates. We have found a level of >80 ppt(v) for methyl nitrate. This level if it can be confirmed in a systematic survey requires a strong biogenic source of methyl nitrate in the Antarctic Ocean.

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“…Background values, summarized in Table 3, were identified from the literature [45][46][47][48][49][50][67][68][69][70][71][72][73][74][75] for 28 HAPs from measurement studies characterized as rural/ remote, hemispheric baseline, remote ocean, global background, or other terms denoting contributions from only natural sources or long-range transport. For these HAPs, the estimated concentration in each census tract is determined by summing together the estimated background value and the modeled concentrations arising from current emissions.…”

Section: Background Concentrationsmentioning

confidence: 99%

National Estimates of Outdoor Air Toxics Concentrations

Rosenbaum

Axelrad

Woodruff

et al. 1999

Journal of the Air & Waste Management Association

103

120

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The Clean Air Act identifies 189 hazardous air pollutants (HAPs), or "air toxics," associated with a wide range of adverse human health effects. The U.S. Environmental Protection Agency has conducted a modeling study with the Assessment System for Population Exposure Nationwide (ASPEN) to gain a greater understanding of the spatial distribution of concentrations of these HAPs resulting from contributions of multiple emission sources. The study estimates year 1990 long-term outdoor concentrations of 148 air toxics for each census tract in the continental United States, utilizing a Gaussian air dispersion modeling approach. Ratios of median national modeled concentrations to estimated emissions indicate that emission totals without consideration of emission source type can be a misleading indicator of air quality. The results also indicate priorities for improvements in modeling methodology and emissions identification. Model performance evaluation suggests a tendency for underprediction of observed concentrations, which is likely due, at least in part, to a number of limitations of the Gaussian modeling formulation. Emissions estimates for HAPs have a high degree of uncertainty and contribute to discrepancies between modeled and monitored concentration estimates. The model's ranking of concentrations among monitoring sites is reasonably good for most of the gaseous HAPs evaluated, with ranking accuracy ranging from 66 to 100%.

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Global Distribution of Tetrachloroethene in the Troposphere: Measurements and Modeling

Cited by 42 publications

References 45 publications

Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene from the AGAGE observations at Mace Head, Ireland, and Cape Grim, Tasmania

Global trends, seasonal cycles, and European emissions of dichloromethane, trichloroethene, and tetrachloroethene from the AGAGE observations at Mace Head, Ireland, and Cape Grim, Tasmania

Levels and pattern of volatile organic nitrates and halocarbons in the air at Neumayer Station (70°S), Antarctic

National Estimates of Outdoor Air Toxics Concentrations

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