期刊
GLOBAL BIOGEOCHEMICAL CYCLES
卷 26, 期 -, 页码 -出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2010GB004028
关键词
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资金
- NSF-OPP [0823101]
- NASA
In connection with the Palmer LTER program, mixed layer water samples were collected during the cruise of the L. M. Gould in Jan., 2008 at 49 stations on a 20 x 100 km grid in the West Antarctica Peninsula (WAP) region of the Southern Ocean. In this study, [O-2]/[Ar] ratios and the triple isotope composition of dissolved O-2 were measured, and were used to estimate net community O-2 production (NCP) and gross primary O-2 production (GPP), respectively. These estimates are further converted to carbon export production, primary production and the f-ratio. Our measurements give NCP ranging from -3 to 76 mmol O-2 m(-2) day(-1) (-25 to 650 mg C m(-2) day(-1)), and GPP from 40 to 220 mmol O-2 m(-2) day(-1) (180 to 1010 mg C m(-2) day(-1)). The O-2 NCP/GPP ratios range from -0.04 to 0.43, corresponding to f-ratios of -0.08 to 0.83. NCP and the NCP/GPP ratio are highest in the northern coastal areas, and decrease to lower values toward the southern coastal area and the open ocean. The inshore-offshore gradient appears to be regulated primarily by iron availability, as supported by the positive correlation between NCP and F-v/F-m ratios (r(2) = 0.22, p < 0.05). Mixed layer depth (MLD) is inversely correlated with NCP (r(2) = 0.21, p < 0.002) and NCP/GPP (r(2) = 0.21, p < 0.02), and highest NCP occurred in the fresh water lenses probably formed from melted coastal glaciers. These results suggest that export production and the f-ratio increase where water stratification is intensified by input of fresh meltwater, and that mixed layer stratification is the major factor regulating NCP in the inner-shelf and coastal regions. Along-shelf variability of phytoplankton community composition is highly correlated with NCP, i.e., NCP increases when the diatom-dominated community in the south transitions to the cryptophyte-dominated one in the north. A high correlation is also observed between NCP and the logarithm of the surface chlorophyll concentration (r(2) = 0.72, p < 0.0001), which makes it possible to estimate carbon export as a function of Chl a concentration in this region.
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