Interannual variability of carbon fluxes in the North Sea from 1970 to 2006 - Competing effects of abiotic and biotic drivers on the gas-exchange of CO₂

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• 作者：Ina Lorkowski ; ^{ina.lorkowski@zmaw.de} ; Johannes Pä ; tsch ; Andreas Moll ; Wilfried Kü ; hn
• 关键词：North Sea ; carbon budget ; biological carbon pump ; solubility carbon pump ; shelf pump ; ECOHAM
• 刊名：Estuarine ; Coastal and Shelf Science
• 出版年：2012
• 期刊代码：79_02727714
• 类别：env
• 出版时间：20 March, 2012
• 卷：100
• 期：Complete
• 页码：38-57
• 文件大小：1595 K

摘要

The three-dimensional biogeochemical model ECOHAM was applied to the Northwest European Continental Shelf (NECS) (47掳 41鈥?- 63掳 53鈥?N, 15掳 5鈥?W - 13掳 55鈥?E) for the years 1970-2006. The development of annual carbon fluxes was analysed for the North Sea as the inner shelf region. We divided the North Sea into several regions, the northern North Sea, the southern North Sea, the German Bight and the Southern Bight for a more detailed analysis. To separate the effect of physical and biological processes a second simulation without biology was performed. The results of our method for calculating the biological pCO₂ were in good agreement with the biological pCO₂ calculated after the method of . While in the standard run the North Sea acted as sink for atmospheric CO₂, in the run without biology the North Sea was a continuous source for atmospheric CO₂.

The main drivers of the air-sea flux variability were identified as being temperature, net ecosystem production and pH. The eutrophication due to high riverine nutrient inputs during the 1980s had no significant effect on the air-sea flux of CO₂ because in contrast to net primary production, net ecosystem production did not respond to the period of higher phosphate input. The increase of sea surface temperature of 0.027聽掳C聽yr^鈭? over the simulation period and the pH decline of 0.002聽yr^鈭? led to a decline of the uptake of atmospheric CO₂ by the North Sea of about 30%in the last decade of the simulation period. A special feature occurred in the year 1996, where a cold sea surface temperature anomaly led to an additional (physical) uptake of atmospheric CO₂ and corresponded with a low primary and net ecosystem production, which on the other hand led to less biologically induced uptake of CO₂.

Our results indicate an ongoing decline of the uptake capacity for atmospheric carbon dioxide of the North Sea for future scenarios.