Decadal changes in atmospheric CO2 concentration and delta C-13 over two seas and two oceans: Italy to New Zealand
| Autor: | Longinelli, A, Lenaz, R, Ori, C, Langone, L, Selmo, E, Giglio, FLonginelli, A, Giglio, F |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Mediterranean climate
Atmospheric Science δ13C Northern Hemisphere d13C of atmospheric CO2 Mediterranean Red Sea chemistry.chemical_compound Oceanography Mediterranean sea chemistry Isotopes of carbon Carbon dioxide Trend surface analysis Environmental science Atmospheric CO2 concentration Southern Ocean Air mass General Environmental Science |
| Zdroj: | Atmospheric environment (1994) 44 (2010): 4303–4311. doi:10.1016/j.atmosenv.2010.05.038 info:cnr-pdr/source/autori:Longinelli, A; Lenaz, R; Ori, C; Langone, L; Selmo, E; Giglio, FLonginelli, A; Lenaz, R; Ori, C; Langone, L; Selmo, E; Giglio, F/titolo:Decadal changes in atmospheric CO2 concentration and delta C-13 over two seas and two oceans: Italy to New Zealand/doi:10.1016%2Fj.atmosenv.2010.05.038/rivista:Atmospheric environment (1994)/anno:2010/pagina_da:4303/pagina_a:4311/intervallo_pagine:4303–4311/volume:44 |
| DOI: | 10.1016/j.atmosenv.2010.05.038 |
| Popis: | Continuous measurements of the CO 2 concentration were repeatedly carried out from 1996 to 2007 between Italy and New Zealand by means of a Siemens Ultramat 5E analyzer assembled for shipboard use. Along the ship routes discrete air samples were collected from 1998 to 2005 using four-litre Pyrex flasks. The δ 13 C of the CO 2 from the flask air samples was measured according to well-established techniques. The decadal changes of these two variables can now be evaluated from these results. Large variations of the CO 2 concentration were normally recorded in the Mediterranean and the Red Sea. Completely different trends of the CO 2 concentration were observed in the Red Sea (30° N to about 13° N) between 2007 (a marked southward decrease) and 2005 and 2003 when a marked southward increase is apparent, at least between 23° and 13° N. A further difference among different expeditions is related to the decrease or increase of the CO 2 concentration in the Gulf of Aden. The backward trajectories of the air masses help to explain, at least partially, these differences. In the Indian Ocean and Southern Ocean a decrease of a few ppmv of the CO 2 concentration takes place from Cape Guardafui (Northern Somaliland) to southern New Zealand, particularly during 2005 and 2007. The yearly rate of increase of the CO 2 concentration between 1996 and 2007 for the Indian Ocean is of about 1.9 ppmv yr −1 , in excellent agreement with the NOAA/CMDL measurements carried out during the same period at Mahe Isld. (Indian Ocean) and Cape Grim (Tasmania). The δ 13 C results obtained from the CO 2 of flask samples collected in the Mediterranean show the effect of anthropogenic emissions, though this is considerably smaller than expected. This inconsistency may be related to the large terrestrial biospheric sink of CO 2 in the Northern Hemisphere. The results obtained from the Red Sea are quite variable through time and space, particularly in its southern section; their interpretation is not easy. The Indian Ocean and the Southern Ocean show rather homogeneous δ 13 C results even though a variable carbon isotope shift can be calculated from period/cruise to period/cruise. In the case of the Indian Ocean the mean δ 13 C value from the flask air samples collected in 2005 is −8.29‰ and the calculated rate of the carbon isotope shift between 1998 and 2005 is −0.034‰ yr −1 , considerably larger than that calculated at the closest NOAA station (Mahe Isld.) of −0.026‰ yr −1 . This discrepancy may be, at least partially, caused by the small number of measurements carried out at sea. However, the atmosphere over the Indian Ocean is less affected by anthropogenic emissions than in other areas. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|