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Longterm accumulation of anthropogenic CO2

Recognizing the need to constrain the oceanic uptake, transport and storage of anthropogenic CO2 during the anthropo-cene as well as to provide a baseline for future estimates of oceanic CO2 uptake, two international ocean research programmes, the World Ocean Circulation Experiment (WOCE) and the Joint Global Ocean Flux Study (JGOFS), jointly conducted a comprehensive survey of inorganic carbon distributions in the global ocean in the 1990s (Wallace, 2001). After completion of the US field...

Rayleigh fractionation

Given that the emissions of N2O are enriched in light isotopologues, the isotopic composition of N2O in the troposphere is unexpectedly heavy. As there are no sinks of N2O in the troposphere, there must be an additional flux of heavy N2O to the troposphere. The source of this flux is the stratosphere. Moore (1974) first observed that the stratosphere is enriched in heavy N2O and since then many other measurements have confirmed this. The heavy N2O is introduced into the lower atmosphere through...

Nh3 Nh2oh No2

Nitrous oxide (N2O) production by nitrifiers and denitrifiers. (From Wrage et al., 2001.) applications have been shown to double N2O emission rates from forest soils (Regina et al., 1998). Furthermore, an increased input of nitrogen deposition affects the nitrogen leaching or runoff from forests (Dise et al., 1998 Gundersen et al., 1998 De Vries et al., 2003a), causing an elevated indirect N2O emission from surface waters (Fig. 17.1). Atmospheric nitrogen deposition may also increase...

References

Anastas, P.T., Webster, L.C. and Williamson, T.C. (1996) Environmentally benign production of commodity chemicals through biotechnology recent progress and future potential. In Green Chemistry. ACS Symposium Series 626, pp. 198-211. Anpo, M., Zhag, S.G., Fujii, Y., Yamashita, H., Koyano, K. and Tatsumi, K.T. (1997) Photocatalytic reduction of CO2 with H2O on Ti-MCM-41 and Ti-MCM-48 mesoporous zeolites at 328K. Chemistry Letters 7, 659-660. Arakawa, H. (1998) Research and development on new...

The Role of Soil Carbon Sequestration in Climate Mitigation over the Next Century

The future trajectory of carbon emissions over the next century depends upon many factors. The IPCC recently developed a range of standard reference emission scenarios (SRES) to provide estimates of possible emissions under a range of different possible futures (IPCC, 2000b). These possible futures depend upon the degree to which society or policy becomes global and whether environmental or economic concerns take precedence in the next century. Among the A1 family of scenarios (global - free...

Permanence and leakage a special problem for carbon sequestration

Leakage is a concern for climate change as the cap that is set, presumably based on a solid assessment of acceptable emissions of carbon to the atmosphere, is not met because reductions taken by some entities are offset by an increase in emissions by entities not under the cap. As permanence is analogous to the spatial leakage problem, it is useful to refer to it as temporal leakage. Spatial leakage occurs because, at a given time, some emitters are not covered by the cap. Temporal leakage...

Controls on N2O production

N2O can be both produced and consumed during denitrification the magnitude and direction of N2O exchange between the soil and atmosphere therefore reflect the net amount of these two opposing processes. The rate of production depends not only on the amount of nitrogen that is nitrified and or Fig. 5.1. Possible ecological niches for nitrogen transformation pathways in fertilized soils. (Redrawn from Wrage et al., 2001.) Fig. 5.1. Possible ecological niches for nitrogen transformation pathways...

Managed carbon sequestration in terrestrial biomass

There is an acceptance that, if used as part of a portfolio of carbon management options, managed sequestration of carbon in terrestrial biomass could have significant contribution to attempts to slow the rise of Ca in the coming decades (Caldiera et al., 2004). The 'coming decades' time frame is significant as models suggest that the future trajectory of Ca rise during the rest of the century will be set in these coming decades. Watson et al. (2000) recognized this potential and concluded that...

Mechanisms of organic carbon burial marine productivity and sedimentation

We can expect that the sedimentary burial flux of carbon will scale in some way with the strength of productivity in the overlying ocean. All we have to do in order to obtain a stronger geologic sink is to increase primary productivity. One way would be to increase the rate of upwelling of deep waters, thus supplying more nutrients such as phosphate (PO4) to the ocean surface where photosynthesis takes place. However, most ocean circulation models predict that the ocean is likely to become more...

Observed Sinks for N2O

Only a few studies are available on observed sinks for N2O. Table 15.1 presents selected examples of observed sinks for N2O. As explained earlier, most terrestrial and aquatic systems have the potential to act Fertilized grassland, poorly drained loamy soil, Berkshire, UK Fertilized grassland, Siggen, south-west Germany Unfertilized grassland, loam, poorly drained, Guelph, Ontario, Canada Unfertilized grassland, clay loam, well-drained, Guelph, Ontario, Canada Fertilized rice paddy, early rice,...

Impact of nitrogen deposition on net emissions of CO2 N2O and CH4 by European forests

A comparison of the net exchange of the three investigated GHGs by European forests can best be done in terms of their GWP. The GWP is an index defined as the cumulative radiative forcing between the present and a chosen future time horizon (by convention 100 years), caused by a unit mass of gas emitted at present (by convention CO2). Using this approach, N2O and CH4 emissions are expressed in terms of CO2 equivalents. In this study it is assumed that 1 kg N2O equals 296 kg CO2 equivalents and...

Andy Ridgwell1 and Ursula Edwards2

1 School of Geographical Sciences, University of Bristol, Bristol, UK 2Occidental Oil and Gas Corporation, Houston, Texas, USA The sequestering (locking up) of carbon in geological formations and removal of carbon dioxide (CO2) from the atmosphere is not a unique, human-driven invention thought up for ameliorating (reducing) the degree of greenhouse gas-driven climate change in the future. CO2 has been spewing from volcanoes on land and the spreading ridges of the ocean throughout geological...

[N2OJa 1I1d1

Where a(l) is the absorption cross section at wavelength l, I(l) is the spectrum of the photolysing radiation or actinic flux and N2O is the local concentration of N2O. The actinic flux is a measure of the direct, scattered and reflected radiation, and varies significantly with time and location. This produces considerable variation in the photolysis rate. It is not surprising then that the N2O photolysis rate peaks near the equator where the solar radiation is greatest. In the remainder of the...

The Inorganic Carbonate Carbon Sedimentary Sink for Fossil Fuel CO2

To see where carbonate rocks come into the greenhouse sink picture, we recap on the sequence of different fates that befall CO2 released to the atmosphere through anthropogenic activities such as the burning of fossil fuels and cement production (Fig. 6.4). Some of the added CO2 may be relatively quickly removed from the atmosphere and taken up by the terrestrial biosphere as a result of 'CO2 fertilization' of plant productivity (although nutrient limitation may limit the importance of this...

Geologic carbon sinks the weathering of silicate rocks on land

Some tens of thousands of years after the burning of fossil fuels has ceased, 8 of fos sil fuel CO2 emissions (assumed to be 4167 Pg C here) will remain in the atmosphere. The atmospheric CO2 concentration is 435 ppm, compared with 376 ppm in 2003 (Keeling and Whorf, 2005) and a pre-Industrial value of 278 ppm (Enting et al., 1994). This would probably give half as much climate change as has already occurred to date. Is this the 'end of the road', or does the geologic carbon sink have any...

Physical removal wet and dry deposition

Henry's law constant, H(T0), for CH4 is very small and it is therefore unlikely that CH4 will partition into the aqueous phase. Hence, physical removal by wet deposition (i.e. removal from the atmosphere by uptake into rain or aerosol species) will not be a significant sink for CH4. Table 11.2 summarizes some Henry's law constants for a range of C1 compounds found in the atmosphere for comparison, from which it Table 11.1. Sources of methane (CH4) in the atmosphere. (From IPCC, 1996.) Table...

Measurement monitoring and enforcement

Much scientific attention is directed at developing and improving the reliability of techniques to estimate the stock of soil carbon at a particular time. This is important and essential work, and more progress is needed. There will, however, always be uncertainty and inaccuracy in these measurements. Measurement error need not be fatal to including carbon sequestration in a cap-and-trade system. A trading system can operate as long as the measurement process is accepted as defining an...

Effect on N2O emissions

Assessing the influence of tillage systems on N2O emissions is not straightforward. Farming systems include a complex mix of tillage tools, timings and frequencies, combined with variations in fertilizer and residue management and crop type, all interacting with local climate, topography and soil type. Soil conditions in NT systems differ from those in tilled systems in several ways SOC and microbial biomass tend to be concentrated near the surface because residues are not buried bulk density...