February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 3, NUMBER 3, MARCH 1990
ATMOSPHERIC AND OCEANIC CHEMISTRY
Nitrification Rates and 15N Abundances of N2O and NO3- in the Western
North Pacific," N. Yoshida (Dept. Earth Sci., Toyama Univ., Gofuku, Toyama
930, Japan), H. Morimoto et al., Nature, 342(6252), 895-897,
Dec. 21/28, 1989.
Reports simultaneous measurements of the nitrification rates and isotope
data. The amount of N2O-produced nitrification is much lower than expected from
the production of NO3-; N2O in the oxygen-deficient layer is more enriched in
15N than NO3-. Results imply that the contribution of nitrification to the
production of N2O is lower than previously thought and that denitrification is
primarily responsible for the production of N2O.
"Short-Term Changes in the Partial Pressure of CO2 in Eastern
Tropical Atlantic Surface Seawater and in Atmospheric CO2 Mole Fraction,"
C. Oudot (Inst. Fr. Res. Sci. Develop. Coop. (ORSTOM), B.P. 1386, Dakar, Sénégal),
C. Andrié, Tellus, 41B(5), 537-553, Nov. 1989.
Presents continuous CO2 observations made at 3 long-duration oceanic
stations (8 to 12 days) in the eastern tropical Atlantic. At the first location,
the ocean surface was generally slightly undersaturated with respect to the
atmosphere. At the second location, Guinea Dome, the ocean surface was an
important source of CO2 for the atmosphere. The net CO2 flux calculated from
mean data is lower (about 30%) than the net CO2 flux calculated from data taken
over short time intervals. In the Guinea Dome area in summer, the net CO2 flux
can be as high as in the equatorial area.
"Modelling the Seasonal Contribution of a CO2 Fertilization Effect
of the Terrestrial Vegetation to the Amplitude Increase in Atmospheric CO2 at
Mauna Loa Observatory," G.H. Kohlmaier (Inst. Phys. Theor. Chem.,
Niederurseler Hang, Goethe-Univ. Frankfurt/M, D-6000 Frankfurt 50, FRG), E.-O.
Siré et al., ibid., 487-510.
Previous global carbon cycle studies suggest that an observed increase of
the amplitude of the seasonal cycle of CO2 may be entirely due to a CO2
fertilization effect on the terrestrial biota. Comparison of the modelled
amplitude increase with the observed shows that external effects other than
fertilization are operating. For instance: (1) the seasonality of the fossil
fuel consumption in the Northern Hemisphere, which is nearly in phase with the
relative uptake or release of CO2 by the land vegetation, and (2) the seasonally
different transequatorial transport of fossil fuel carbon.
"Climate-Induced Feedbacks for the Global Cycles of Methane and
Nitrous Oxide," M.A.K. Khalil (Inst. Atmos. Sci., Oregon Grad. Ctr.,
Beaverton OR 97006), R.A. Rasmussen, ibid., 554-559.
Measurements indicate CH4 and nitrous oxide both decreased during the little
ice age between 1450 and 1750; the authors believe these decreases were the
response of emissions from the earth's soils, oceans and wetlands to global
climatic change. The combination of the response of wetlands and permafrost to
global warming may add as much or more CH4 and nitrous oxide to the atmosphere
as expected from increasing anthropogenic sources. The global warming that has
apparently occurred over the past century may already have produced about 20% of
the increase of nitrous oxide between the pre-industrial times and the present.
"Seasonal Variation of Methane Emissions from a Temperate Swamp,"
J.O. Wilson (NASA Langley Res. Ctr., MS 483, Hampton VA 23665), P.M. Crill et
al., Biogeochem., 8(1), 55-71, July 1989.
Methane flux measurements made at four sites over a 13-month period show a
strong seasonal variation. Highest emission rates were observed in early spring
and again in late summer in association with changes in plant growth and
physiology. A comparison of flux measurements from fresh and saline wetlands in
the immediate area of Newport News Swamp emphasizes the importance of edaphic
factors in controlling flux.
"Trace Gases in the Atmosphere Above the Ocean," V.M. Koropalov
(Inst. Appl. Geophys.), YE.V. Kryukov et al., Izvestiya, Atmos., Ocean.
Phys., 24(8), 1988 (translated edition Mar. 1989).
Presents measurements of several trace gases obtained during the Soviet-U.S.
gas-aerosol experiments in the Pacific Ocean (SAGATEX-83). The zonal
concentration gradients of CF2Cl2, CFCl3, CCl4, CH3CCl3, CH4 and C2Cl4 in the
ocean atmosphere are determined. Simultaneous measurements of the partial
pressure of CO2 in the surface layer of the ocean and in the atmospheric
boundary layer are used to determine the flux of CO2 between the atmosphere and
ocean in the equatorial zone.
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