Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 10, 3715-3729, 2013
http://www.biogeosciences.net/10/3715/2013/
doi:10.5194/bg-10-3715-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
05 Jun 2013
The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study
A. Lindenthal1, B. Langmann1, J. Pätsch2, I. Lorkowski2, and M. Hort1 1Institute of Geophysics, KlimaCampus, University of Hamburg, Hamburg, Germany
2Institute of Oceanography, KlimaCampus, University of Hamburg, Hamburg, Germany
Abstract. In high-nutrient–low-chlorophyll regions, phytoplankton growth is limited by the availability of water-soluble iron. The eruption of Kasatochi volcano in August 2008 led to ash deposition into the iron-limited NE Pacific Ocean. Volcanic ash released iron upon contact with seawater and generated a massive phytoplankton bloom. Here we investigate this event with a one-dimensional ocean biogeochemical column model to illuminate the ocean response to iron fertilisation by volcanic ash. The results indicate that the added iron triggered a phytoplankton bloom in the summer of 2008. Associated with this bloom, macronutrient concentrations such as nitrate and silicate decline and zooplankton biomass is enhanced in the ocean mixed layer. The simulated development of the drawdown of carbon dioxide and increase of pH in surface seawater is in good agreement with available observations. Sensitivity studies with different supply dates of iron to the ocean emphasise the favourable oceanic conditions in the NE Pacific to generate massive phytoplankton blooms in particular during July and August in comparison to other months. By varying the amount of volcanic ash and associated bio-available iron supplied to the ocean, model results demonstrate that the NE Pacific Ocean has higher, but limited capabilities to consume CO2 after iron fertilisation than those observed after the volcanic eruption of Kasatochi.

Citation: Lindenthal, A., Langmann, B., Pätsch, J., Lorkowski, I., and Hort, M.: The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study, Biogeosciences, 10, 3715-3729, doi:10.5194/bg-10-3715-2013, 2013.
Publications Copernicus
Download
Share