Globale Isotopenluftchemie des Treibhausgases Kohlendioxid Abschlussbericht

High precision atmospheric "1"4CO_2 observations at 6 globally distributed background stations have been continued, and extended by two new observational sites in the tropics and in the subantarctic ocean. This unique data set of continuous "1"4CO_2 observations has been used to verify global models of atmospheric CO_2. With the current understanding of the CO_2 sources and sinks, the observed seasonal variations of "1"4CO_2 in the northern hemisphere cannot be explained quantitatively. Particularly unclear is the impact of the biospheric sub-reservoirs with different "1"4C ages on the observed seasonality. Moreover, the "1"4CO_2 level at the southern hemispheric sites, which is mainly determined by equilibration with "1"4C depleted surface ocean water in the circum Antarctic regions, cannot fully be explained by our model estimates. A particularly important finding from our model results is a serious imbalance of bomb "1"4C between all reservoirs exchanging carbon with the atmosphere. The most plausible adjustment of the CO_2 exchange parameters between the carbon reservoirs suggests a smaller uptake of anthropogenic CO_2 by the oceans than previously believed. The global atmospheric observations of "8"5Krypton show a slow down of the increase rates in the last 3 years in both hemisphere. This feature can be qualitatively explained by reduced "8"5Krypton emissions from reprocessing plants of the Former Sowjet Union. Within the southern hemisphere, we observe a significant concentration difference between 41 S and 71 S which can only be explained by a yet unidentified "8"5Krypton source in the southern hemisphere. (orig.)SIGLEAvailable from TIB Hannover: F95B629+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Time series of the partial pressure of carbon dioxide (2001-2004) and preliminary inorganic carbon budget in the Scheldt plume (Belgian coastal waters)

A 4-year time series (2001–2004) of the partial pressure of CO2 (pCO2) and air-sea CO2 fluxes is reported in the Scheldt estuarine plume. This system is oversaturated in CO2 with respect to the atmosphere, except during the spring phytoplanktonic bloom, and acts as a net source of CO2 to the atmosphere of 0.7 mol C m-2 yr-1 that represents 7 to 27% of the inner Scheldt estuary CO2 emission. Results also highlight that a high spatial and temporal coverage of the surface pCO2 in coastal ecosystems is crucial for reliable estimations of air-sea CO2 fluxes. The seasonal variations of pCO2 seem to be more dominated by biological activities (photosynthesis/respiration) than by temperature change. A stochiometrically linked C/P mass balance budget failed to provide net ecosystem production estimates consistent with the pCO2 dynamics in this area. It is hypothesized that this discrepancy is related to physiological characteristics of the dominant phytoplanktonic species (Phaeocystis sp.) within the studied area. On the basis of a preliminary dissolved inorganic carbon input/output budget, the annual emission of CO2 toward the atmosphere seems to be largely due to the outgassing of the inputs of CO2 from the inner Scheldt estuary, rather than due to organic carbon degradation. [KEYWORDS: CO2 air-sea fluxes ; Belgian coastal water; Scheldt estuary.]