Biological pump and vertical mixing in the Southern Ocean:: Their impact on atmospheric CO2

被引:17
作者
Popova, EE
Ryabchenko, VA
Fasham, MJR
机构
[1] Southampton Oceanog Ctr, Southampton SO14 3ZH, Hants, England
[2] Russian Acad Sci, PP Shirshov Oceanol Inst, St Petersburg Branch, St Petersburg 199053, Russia
关键词
D O I
10.1029/1999GB900090
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
A global box model simulating nitrogen and carbon cycling in the ocean has been developed. The distinctive feature of the model is the detailed description of the seasonal cycles of the oceanic upper mixed layer (UML) ecosystem. Unlike other ocean regions, phytoplankton productivity in the Southern Ocean is assumed to be limited by low iron availability, leading to twofold decrease in the phytoplankton growth rate. Calculated ecosystem and carbon cycle characteristics are in a good agreement with available observational data and conceptual models of generalized phytoplankton seasonal cycles in the world ocean. The model estimates of the global ocean new production outside of shelf regions and the preindustrial atmospheric pCO(2) are 9.9 Ct C/yr and 282 ppm, respectively. Results of numerical experiments with the model showed that the potential new production which might be reached by allowing phytoplankton maximum growth rate to increase is 29 Gt C/yr (76% of this increase is contributed by the Southern Ocean) and corresponds to an atmospheric pCO(2) of 205 ppm; however, this would require an unrealistic tenfold increase in growth rate. The large contribution of the Southern Ocean is accounted for by the high-nutrient, low-chlorophyll (HNLC) conditions existing in this region caused by the high dissolved inorganic nitrogen concentrations below the UML, deep mixing during the austral summer, and iron limitation of phytoplankton productivity. A realistic (twofold) increase in the phytoplankton growth rate in the Southern Ocean which can be considered as a maximal effect of iron fertilization results in the lowering of atmospheric pCO(2) by only 10 ppm. Changes in the UML depth in the Southern Ocean (a wintertime shallowing and summertime deepening of the UML in comparison with preindustrial conditions) could lead to a decrease of atmospheric pCO(2) by 15 ppm at the most. The combined effect of iron fertilization and these changes in vertical mixing might constitute about 30-35 ppm, that is, less than one half of the lowering of 80 ppm during the last glaciation.
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页码:477 / 498
页数:22
相关论文
共 61 条
[1]   Oceanic primary production .2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll [J].
Antoine, D ;
Andre, JM ;
Morel, A .
GLOBAL BIOGEOCHEMICAL CYCLES, 1996, 10 (01) :57-69
[2]  
BAINBRIDGE A, 1981, HYDROGRAPHYC DATA 19, V1
[3]   RATES OF PHYTOPLANKTON CELL-DIVISION IN THE FIELD AND IN IRON ENRICHMENT EXPERIMENTS [J].
BANSE, K .
LIMNOLOGY AND OCEANOGRAPHY, 1991, 36 (08) :1886-1898
[4]   Low seasonality of low concentrations of surface chlorophyll in the Subantarctic water ring: underwater irradiance, iron, or grazing? [J].
Banse, Karl .
PROGRESS IN OCEANOGRAPHY, 1996, 37 (3-4) :241-291
[5]  
BERGER WH, 1987, 8730 SCRIPPS I OC, P1
[6]  
BOLIN B, 1983, TELLUS B, V35, P206, DOI 10.1111/j.1600-0889.1983.tb00025.x
[7]   CARBON-CYCLE - 1985 GLACIAL TO INTERGLACIAL CHANGES IN THE OPERATION OF THE GLOBAL CARBON-CYCLE [J].
BROECKER, WS ;
PENG, TH .
RADIOCARBON, 1986, 28 (2A) :309-327
[8]   OCEAN CHEMISTRY DURING GLACIAL TIME [J].
BROECKER, WS .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1982, 46 (10) :1689-1705
[9]  
BROECKER WS, 1982, HYDROGRAPHYC DATA 19, V3
[10]  
CONKRIGHT M, 1994, WORLD OCEAN ATLAS 19, V1