Trace gases are gases that are present in small amounts within an environment such as a planet's atmosphere. Trace gases in Earth's atmosphere are gases other than nitrogen (78.1%), oxygen (20.9%), and argon (0.934%) which, in combination, make up 99.934% of its atmosphere (not including water vapor).
The abundance of a trace gas can range from a few parts per trillion (ppt) by volume to several hundred parts per million by volume (ppmv).[1] When a trace gas is added into the atmosphere, that process is called a source. There are two possible types of sources - natural or anthropogenic. Natural sources are caused by processes that occur in nature. In contrast, anthropogenic sources are caused by human activity.
Some sources of a trace gas are biogenic processes, outgassing from solid Earth, ocean emissions, industrial emissions, and in situ formation.[1] A few examples of biogenic sources include photosynthesis, animal excrements, termites, rice paddies, and wetlands. Volcanoes are the main source for trace gases from solid earth. The global ocean is also a source of several trace gases, in particular sulfur-containing gases. In situ trace gas formation occurs through chemical reactions in the gas-phase.[1] Anthropogenic sources are caused by human related activities such as fossil fuel combustion (e.g. in transportation), fossil fuel mining, biomass burning, and industrial activity.
In contrast, a sink is when a trace gas is removed from the atmosphere. Some of the sinks of trace gases are chemical reactions in the atmosphere, mainly with the OH radical, gas-to-particle conversion forming aerosols, wet deposition and dry deposition.[1] Other sinks include microbiological activity in soils.
Below is a chart of several trace gases including their abundances, atmospheric lifetimes, sources, and sinks.
A The Intergovernmental Panel on Climate Change (IPCC) states that "no single atmospheric lifetime can be given" for CO2.[4]: 731 This is mostly due to the high rate of growth and large cumulative magnitude of the disturbances to Earth's carbon cycle by the geologic extraction and burning of fossil carbon.[5] As of year 2014, fossil CO2 emitted as a theoretical 10 to 100 GtC pulse on top of the existing atmospheric concentration was expected to be 50% removed by land vegetation and ocean sinks in less than about a century.[6] A substantial fraction (20-35%) was also projected to remain in the atmosphere for centuries to millennia, where fractional persistence increases with pulse size.[7][8] Thus CO2 lifetime effectively increases as more fossil carbon is extracted by humans.
Mixing and lifetime
The overall abundance of man-made trace gases in Earth's atmosphere is growing. Most originate from industrial activity in the more populated northern hemisphere. Time-series data from measurement stations around the world indicate that it typically takes 1-2 years for their concentrations to become well-mixed throughout the troposphere.[9][10]
The residence time of a trace gas depends on the abundance and rate of removal. The Junge (empirical) relationship describes the relationship between concentration fluctuations and residence time of a gas in the atmosphere. It can expressed as fc = b/τr, where fc is the coefficient of variation, τr is the residence time in years, and b is an empirical constant, which Junge originally gave as 0.14 years.[11] As residence time increases, the concentration variability decreases. This implies that the most reactive gases have the most concentration variability because of their shorter lifetimes. In contrast, more inert gases are non-variable and have longer lifetimes. When measured far from their sources and sinks, the relationship can be used to estimate tropospheric residence times of gases.[11]
The most influential greenhouse gas is water vapor. It frequently occurs in high concentrations, may transition to and from an aerosol (clouds), and is thus not generally classified as a trace gas. Regionally, water vapor can trap up to 80 percent of outgoing IR radiation.[12] Globally, water vapor is responsible for about half of Earth's total greenhouse effect.[13]
The second most important greenhouse gas, and the most important trace gas affected by man-made sources, is carbon dioxide.[12] It contributes about 20% of Earth's total greenhouse effect.[13] The reason that greenhouse gases can absorb infrared radiation is their molecular structure. For example, carbon dioxide has two basic modes of vibration that create a strong dipole moment, which causes its strong absorption of infrared radiation.[12]
In contrast, the most abundant gases (N 2,O 2, and Ar) in the atmosphere are not greenhouse gases. This is because they cannot absorb infrared radiation as they do not have vibrations with a dipole moment.[12] For instance, the triple bonds of atmospheric dinitrogen make for a symmetric molecule with vibrational energy states that are almost totally unaffected at infrared frequencies.
Below is a table of some of the major trace greenhouse gases, their man-made sources, and an estimate of the relative contribution of those sources to the enhanced greenhouse effect that influences global warming.
rice fields, cattle and dairy cows, landfills, oil and gas production
15%
Nitrous oxide
N2O
fertilizers, deforestation
6%
References
^ abcdeWallace, John; Hobbs, Peter (2006). Atmospheric Science: An Introductory Survey. Amsterdam, Boston: Elsevier Academic Press. ISBN9780127329512.
^"Trends in Atmospheric Carbon Dioxide". NOAA Earth System Research Laboratories. Retrieved 2022-01-20.
^"Trends in Atmospheric Methane". NOAA Earth System Research Laboratories. Retrieved 2022-01-20.
^"Chapter 8". AR5 Climate Change 2013: The Physical Science Basis.
^Friedlingstein, P., Jones, M., O'Sullivan, M., Andrew, R., Hauck, J., Peters, G., Peters, W., Pongratz, J., Sitch, S., Le Quéré, C. and 66 others (2019) "Global carbon budget 2019". Earth System Science Data, 11(4): 1783–1838. doi:10.5194/essd-11-1783-2019
^"Figure 8.SM.4" (PDF). Intergovernmental Panel on Climate Change Fifth Assessment Report - Supplemental Material. p. 8SM-16.
^Archer, David (2009). "Atmospheric lifetime of fossil fuel carbon dioxide". Annual Review of Earth and Planetary Sciences. 37 (1): 117–34. Bibcode:2009AREPS..37..117A. doi:10.1146/annurev.earth.031208.100206. hdl:2268/12933.
^Joos, F.; Roth, R.; Fuglestvedt, J.D.; et al. (2013). "Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics: A multi-model analysis". Atmospheric Chemistry and Physics. 13 (5): 2793–2825. doi:10.5194/acpd-12-19799-2012.
^"Long-term global trends of atmospheric trace gases". NOAA Earth System Research Laboratories. Retrieved 8 January 2022.
^"AGAGE Data and Figures". Massachusettes Institute of Technology. Retrieved 8 January 2022.
^ abSlinn, W. G. N. (1988). "A Simple Model for Junge's Relationship between Concentration Fluctuations and Residence Times for Tropospheric Trace Gases". Tellus B: Chemical and Physical Meteorology. 40 (3): 229–232. doi:10.3402/tellusb.v40i3.15909.
^ abcdeTrogler, William C. (1995). "The Environmental Chemistry of Trace Atmospheric Gases". Journal of Chemical Education. 72 (11): 973. doi:10.1021/ed072p973.
^ abGavin Schmidt (2010-10-01). "Taking the Measure of the Greenhouse Effect". NASA Goddard Institute for Space Studies - Science Briefs.
External links
On trace gases and their role
January 26, 2023
trace, gases, that, present, small, amounts, within, environment, such, planet, atmosphere, earth, atmosphere, gases, other, than, nitrogen, oxygen, argon, which, combination, make, atmosphere, including, water, vapor, contents, abundance, sources, sinks, mixi. Trace gases are gases that are present in small amounts within an environment such as a planet s atmosphere Trace gases in Earth s atmosphere are gases other than nitrogen 78 1 oxygen 20 9 and argon 0 934 which in combination make up 99 934 of its atmosphere not including water vapor Contents 1 Abundance sources and sinks 2 Mixing and lifetime 3 Trace greenhouse gases 4 References 5 External linksAbundance sources and sinks EditThe abundance of a trace gas can range from a few parts per trillion ppt by volume to several hundred parts per million by volume ppmv 1 When a trace gas is added into the atmosphere that process is called a source There are two possible types of sources natural or anthropogenic Natural sources are caused by processes that occur in nature In contrast anthropogenic sources are caused by human activity Some sources of a trace gas are biogenic processes outgassing from solid Earth ocean emissions industrial emissions and in situ formation 1 A few examples of biogenic sources include photosynthesis animal excrements termites rice paddies and wetlands Volcanoes are the main source for trace gases from solid earth The global ocean is also a source of several trace gases in particular sulfur containing gases In situ trace gas formation occurs through chemical reactions in the gas phase 1 Anthropogenic sources are caused by human related activities such as fossil fuel combustion e g in transportation fossil fuel mining biomass burning and industrial activity In contrast a sink is when a trace gas is removed from the atmosphere Some of the sinks of trace gases are chemical reactions in the atmosphere mainly with the OH radical gas to particle conversion forming aerosols wet deposition and dry deposition 1 Other sinks include microbiological activity in soils Below is a chart of several trace gases including their abundances atmospheric lifetimes sources and sinks Trace gases taken at pressure 1 atm 1 Gas Chemical formula Fraction of volume of air by the species Residence time or lifetime Major sources Major sinksCarbon dioxide CO2 419 ppm ppmv May 2021 2 Increasing See Note A Biological oceanic combustion anthropogenic photosynthesisNeon Ne 18 18 ppmv Volcanic Helium He 5 24 ppmv Radiogenic Methane CH4 1 89 ppm May 2021 3 9 years Biological anthropogenic OHHydrogen H2 0 56 ppmv 2 years Biological HCHO photolysis soil uptakeNitrous oxide N2O 0 33 ppmv 150 years Biological anthropogenic O 1D in stratosphereCarbon monoxide CO 40 200 ppbv 60 days Photochemical combustion anthropogenic OHOzone O3 10 200 ppbv troposphere Days months Photochemical photolysisFormaldehyde HCHO 0 1 10 ppbv 1 5 hours Photochemical OH photolysisNitrogen species NOx 10 pptv 1 ppmv Variable Soils anthropogenic lightning OHAmmonia NH3 10 pptv 1 ppbv 2 10 days Biological gas to particle conversionSulfur dioxide SO2 10 pptv 1 ppbv Days Photochemical volcanic anthropogenic OH water based oxidationDimethyl sulfide CH3 2S several pptv several ppbv Days Biological ocean OHA The Intergovernmental Panel on Climate Change IPCC states that no single atmospheric lifetime can be given for CO2 4 731 This is mostly due to the high rate of growth and large cumulative magnitude of the disturbances to Earth s carbon cycle by the geologic extraction and burning of fossil carbon 5 As of year 2014 fossil CO2 emitted as a theoretical 10 to 100 GtC pulse on top of the existing atmospheric concentration was expected to be 50 removed by land vegetation and ocean sinks in less than about a century 6 A substantial fraction 20 35 was also projected to remain in the atmosphere for centuries to millennia where fractional persistence increases with pulse size 7 8 Thus CO2 lifetime effectively increases as more fossil carbon is extracted by humans Mixing and lifetime EditThe overall abundance of man made trace gases in Earth s atmosphere is growing Most originate from industrial activity in the more populated northern hemisphere Time series data from measurement stations around the world indicate that it typically takes 1 2 years for their concentrations to become well mixed throughout the troposphere 9 10 The residence time of a trace gas depends on the abundance and rate of removal The Junge empirical relationship describes the relationship between concentration fluctuations and residence time of a gas in the atmosphere It can expressed as fc b tr where fc is the coefficient of variation tr is the residence time in years and b is an empirical constant which Junge originally gave as 0 14 years 11 As residence time increases the concentration variability decreases This implies that the most reactive gases have the most concentration variability because of their shorter lifetimes In contrast more inert gases are non variable and have longer lifetimes When measured far from their sources and sinks the relationship can be used to estimate tropospheric residence times of gases 11 Trace greenhouse gases EditSee also List of greenhouse gases A few examples of the major greenhouse gases are water carbon dioxide methane nitrous oxide ozone and CFCs These gases can absorb infrared radiation from the Earth s surface as it passes through the atmosphere The most influential greenhouse gas is water vapor It frequently occurs in high concentrations may transition to and from an aerosol clouds and is thus not generally classified as a trace gas Regionally water vapor can trap up to 80 percent of outgoing IR radiation 12 Globally water vapor is responsible for about half of Earth s total greenhouse effect 13 The second most important greenhouse gas and the most important trace gas affected by man made sources is carbon dioxide 12 It contributes about 20 of Earth s total greenhouse effect 13 The reason that greenhouse gases can absorb infrared radiation is their molecular structure For example carbon dioxide has two basic modes of vibration that create a strong dipole moment which causes its strong absorption of infrared radiation 12 In contrast the most abundant gases N2 O2 and Ar in the atmosphere are not greenhouse gases This is because they cannot absorb infrared radiation as they do not have vibrations with a dipole moment 12 For instance the triple bonds of atmospheric dinitrogen make for a symmetric molecule with vibrational energy states that are almost totally unaffected at infrared frequencies Below is a table of some of the major trace greenhouse gases their man made sources and an estimate of the relative contribution of those sources to the enhanced greenhouse effect that influences global warming Key Greenhouse Gases and Sources 12 Gas Chemical formula Major human sources Contribution to Increase Year 1995 estimate Carbon dioxide CO2 fossil fuel combustion deforestation 55 Methane CH4 rice fields cattle and dairy cows landfills oil and gas production 15 Nitrous oxide N2O fertilizers deforestation 6 References Edit a b c d e Wallace John Hobbs Peter 2006 Atmospheric Science An Introductory Survey Amsterdam Boston Elsevier Academic Press ISBN 9780127329512 Trends in Atmospheric Carbon Dioxide NOAA Earth System Research Laboratories Retrieved 2022 01 20 Trends in Atmospheric Methane NOAA Earth System Research Laboratories Retrieved 2022 01 20 Chapter 8 AR5 Climate Change 2013 The Physical Science Basis Friedlingstein P Jones M O Sullivan M Andrew R Hauck J Peters G Peters W Pongratz J Sitch S Le Quere C and 66 others 2019 Global carbon budget 2019 Earth System Science Data 11 4 1783 1838 doi 10 5194 essd 11 1783 2019 Figure 8 SM 4 PDF Intergovernmental Panel on Climate Change Fifth Assessment Report Supplemental Material p 8SM 16 Archer David 2009 Atmospheric lifetime of fossil fuel carbon dioxide Annual Review of Earth and Planetary Sciences 37 1 117 34 Bibcode 2009AREPS 37 117A doi 10 1146 annurev earth 031208 100206 hdl 2268 12933 Joos F Roth R Fuglestvedt J D et al 2013 Carbon dioxide and climate impulse response functions for the computation of greenhouse gas metrics A multi model analysis Atmospheric Chemistry and Physics 13 5 2793 2825 doi 10 5194 acpd 12 19799 2012 Long term global trends of atmospheric trace gases NOAA Earth System Research Laboratories Retrieved 8 January 2022 AGAGE Data and Figures Massachusettes Institute of Technology Retrieved 8 January 2022 a b Slinn W G N 1988 A Simple Model for Junge s Relationship between Concentration Fluctuations and Residence Times for Tropospheric Trace Gases Tellus B Chemical and Physical Meteorology 40 3 229 232 doi 10 3402 tellusb v40i3 15909 a b c d e Trogler William C 1995 The Environmental Chemistry of Trace Atmospheric Gases Journal of Chemical Education 72 11 973 doi 10 1021 ed072p973 a b Gavin Schmidt 2010 10 01 Taking the Measure of the Greenhouse Effect NASA Goddard Institute for Space Studies Science Briefs External links EditA description of atmospheric trace gases On trace gases and their role Retrieved from https en wikipedia org w index php title Trace gas amp oldid 1133979910, 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