Variation in particulate C and N isotope composition following iron fertilization in two successive phytoplankton communities in the Southern Ocean
Berg, G.; Mills, M.; Long, M.; Bellerby, R.; Strass, V.; Savoye, N.; Rottgers, R.; Croot, P.; Webb, A.; Arrigo, K. (2011). Variation in particulate C and N isotope composition following iron fertilization in two successive phytoplankton communities in the Southern Ocean. Global Biogeochem. Cycles 25(3): 16 pp. dx.doi.org/10.1029/2010GB003824 In: Global Biogeochemical Cycles. American Geophysical Union: Washington, DC. ISSN 0886-6236; e-ISSN 1944-9224, more |   |
| Authors | | Top | - Berg, G.
- Mills, M.
- Long, M.
- Bellerby, R.
| - Strass, V.
- Savoye, N., more
- Rottgers, R.
| - Croot, P.
- Webb, A.
- Arrigo, K.
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| Abstract | Surface d15NPON increased 3.92 ± 0.48‰ over the course of 20 days following additions of iron (Fe) to an eddy in close proximity to the Antarctic Polar Front in the Atlantic sector of the Southern Ocean. The change in d15NPON was associated with an increase in the >20 µm size fraction, leading to a maximal difference of 6.23‰ between the >20 µm and <20 µm size fractions. Surface d13CPOC increased 1.18 ± 0.31‰ over the same period. After a decrease in particulate organic matter in the surface layer, a second phytoplankton community developed that accumulated less biomass, had a slower growth rate and was characterized by an offset of 1.56‰ in d13CPOC relative to the first community. During growth of the second community, surface d13CPOC further increased 0.83 ± 0.13‰. Here we speculate on ways that carboxylation, nitrogen assimilation, substrate pool enrichment and community composition may have contributed to the gradual increase in d13CPOC associated with phytoplankton biomass accumulation, as well as the systematic offset in d13CPOC between the two phytoplankton communities. |
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