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Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide
Isotopic Constraints on the Isotopic Constraints on the Global Budget and Trend of Global Budget and Trend of Atmospheric Nitrous OxideAtmospheric Nitrous Oxide
Mao-Chang LiangResearch Center for Environmental Changes, Academia Sinica
Y. L. YungDivisions of Geological and Planetary Sciences, California Institute of
Technology
European Geosciences Union General Assembly 2009, Vienna, Austria, 19 – 24 April 2009
EGU 2009
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
Courtesy of SJ Kao
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
ISI 200 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
N N+ O-
nitrous oxide
14N14N16O (446) _ 14N15N16O (456) -- N 15N14N16O (546) -- N
14N14N18O (448) --18O(δ15N = ½ [δN + δN])
# Source: natural -- land -- ocean anthropogenic -- agriculture, fossil fuels & industry, biomass burning,… # Sink: (stratosphere) -- photolysis and chemistry (~160-220 nm)
N2O continues to increase in the atmosphere. However, contribution of each source is not well-quantified.
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide
EGU 2009
Kim and Craig 1993
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
Liang and Yung 2007
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
EGU 2009 Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide
(1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source(3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary.(6) The lifetimes do not vary with time.
Troposphere
F_ocean F_land
F_anthro.
F_sink
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide
Available measurements:
1. N2O trend
2. 18O
3. 15N ( and )
EGU 2009
(1) Ocean source = prescribed isotopic composition. (2) The isotopic composition of anthropogenic source = land source(3) Solve the mean isotopic composition of land for PRE. (4) Magnitude of the natural and anthropogenic sources are deduced. (5) The strength of STE does not vary.(6) The lifetimes do not vary with time.
Troposphere
F_ocean F_land
F_anthro.
F_sink
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide
Available measurements:
1. N2O trend
2. 18O
3. 15N ( and )
EGU 2009
x: Machida et al. [1995] +: Bernard et al. [2006]
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
x: Rockmann and Levin [2005]x: Park et al. [2009]
Time evolution of δ18O(N2O) and δ15N (N2O)
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
Sources and sinks
OC -- oceanLD -- landAN -- anthropogenicTotal = OC+LD+ANSK -- sinkTD -- trend
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
150 GtC (Broecker 2007)
Models
Source of N2O (in Tg N year-1) †
AR4 Baseline Model Standard Model Extended Model (E1)
Natural sources Soils under natural vegetation 6.6 5.2 5.2 5.2 Oceans 3.8 5 5 5 Atmospheric chemistry 0.6 0 0 0 Natural total 11 10.2 10.2 10.2 Anthropogenic sources
AG+ HE+ ADa 3.6 6.5 5.1 5.5
FF+ BB+ RE b 3.1 0 1.4 3.2 Anthropogenic total 6.7 6.5 6.5 8.7 Total sources 17.7 16.7 16.7 18.9
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009
Use the Caltech/JPL 2-D and MOZART/CAM-CHEM 3-D models for better estimates.
Better measurements are needed as present data have large errors.
Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous OxideEGU 2009