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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 12, 6761-6779, 2015
https://doi.org/10.5194/bg-12-6761-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
26 Nov 2015
Two decades of inorganic carbon dynamics along the West Antarctic Peninsula
C. Hauri1,2, S. C. Doney3, T. Takahashi4, M. Erickson5, G. Jiang6, and H. W. Ducklow4 1International Pacific Research Center, SOEST, University of Hawai'i, Honolulu, HI, USA
2International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA
3Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
4Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
5Antarctic Support Contractor, Arlington, VA, USA
6School of Earth Sciences, University of Melbourne, Melbourne, VIC, Australia
Abstract. We present 20 years of seawater inorganic carbon measurements collected along the western shelf and slope of the Antarctic Peninsula. Water column observations from summertime cruises and seasonal surface underway pCO2 measurements provide unique insights into the spatial, seasonal, and interannual variability in this dynamic system. Discrete measurements from depths > 2000 m align well with World Ocean Circulation Experiment observations across the time series and underline the consistency of the data set. Surface total alkalinity and dissolved inorganic carbon data showed large spatial gradients, with a concomitant wide range of Ωarag (< 1 up to 3.9). This spatial variability was mainly driven by increasing influence of biological productivity towards the southern end of the sampling grid and meltwater input along the coast towards the northern end. Large inorganic carbon drawdown through biological production in summer caused high near-shore Ωarag despite glacial and sea-ice meltwater input. In support of previous studies, we observed Redfield behavior of regional C / N nutrient utilization, while the C / P (80.5 ± 2.5) and N / P (11.7 ± 0.3) molar ratios were significantly lower than the Redfield elemental stoichiometric values. Seasonal salinity-based predictions of Ωarag suggest that surface waters remained mostly supersaturated with regard to aragonite throughout the study. However, more than 20 % of the predictions for winters and springs between 1999 and 2013 resulted in Ωarag < 1.2. Such low levels of Ωarag may have implications for important organisms such as pteropods. Even though we did not detect any statistically significant long-term trends, the combination of on\-going ocean acidification and freshwater input may soon induce more unfavorable conditions than the ecosystem experiences today.

Citation: Hauri, C., Doney, S. C., Takahashi, T., Erickson, M., Jiang, G., and Ducklow, H. W.: Two decades of inorganic carbon dynamics along the West Antarctic Peninsula, Biogeosciences, 12, 6761-6779, https://doi.org/10.5194/bg-12-6761-2015, 2015.
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Short summary
Evaluation of a unique 20-year-long time series of inorganic carbon and nutrient observations from the West Antarctic Peninsula region shows that summertime biological productivity and meltwater input drive a large range of surface aragonite saturation states from values < 1 (undersaturated) up to 3.9. Even though we did not detect any statistically significant long-term trends, ongoing ocean acidification and freshwater input may soon induce more unfavorable conditions than seen today.
Evaluation of a unique 20-year-long time series of inorganic carbon and nutrient observations...
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