Liang and Yung, Isotopic Constraints on the Global Budget and Trend of Atmospheric Nitrous Oxide...

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

Courtesy of SJ Kao


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.


EGU 2009

Kim and Craig 1993


Liang and Yung 2007


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


Available measurements:

1. N2O trend

2. 18O

3. 15N ( and )

EGU 2009

x: Machida et al. [1995] +: Bernard et al. [2006]


x: Rockmann and Levin [2005]x: Park et al. [2009]

Time evolution of δ18O(N2O) and δ15N (N2O)


Sources and sinks

OC -- oceanLD -- landAN -- anthropogenicTotal = OC+LD+ANSK -- sinkTD -- trend


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


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 Oxide...

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