Too bad they did not explore the effect on relative abundance of
phytoplankton. Seabed deposits show that volcanic ash is associated with
increased populations of diatoms - to be expected since diatoms tend to
predominate so long as the silica they need to be build their shells is
present as silicic acid. This has implications for CO2 since diatoms are
effective at sequestering surface water CO2 to deep ocean layers (as
various forms of solid / dissolved C). more so than other phytoplankton.
Oliver.
On 23/03/2013 11:48, Andrew Lockley wrote:
Poster's note : paper from earlier thread, which commentators describe
as demonstrating limited potential for OIF generally, due to low macro
nutrient supply. (Eg
http://news.mongabay.com/2013/0322-iron-fertilization-fail.html)
http://onlinelibrary.wiley.com/doi/10.1002/grl.50221/abstract
Keywords:
iron fertilization;volcanic eruption;Eyjafjallajökull Volcano
Abstract
[1] Aerosol deposition from the 2010 eruption of the Icelandic volcano
Eyjafjallajökull resulted in significant dissolved iron (DFe) inputs
to the Iceland Basin of the North Atlantic. Unique ship-board
measurements indicated strongly enhanced DFe concentrations (up to 10
nM) immediately under the ash plume. Bioassay experiments performed
with ash collected at sea under the plume also demonstrated the
potential for associated Fe release to stimulate phytoplankton growth
and nutrient drawdown. Combining Fe dissolution measurements with
modeled ash deposition suggested that the eruption had the potential
to increase DFe by >0.2 nM over an area of up to 570,000 km2. Although
satellite ocean color data only indicated minor increases in
phytoplankton abundance over a relatively constrained area, comparison
of in situ nitrate concentrations with historical records suggested
that ash deposition may have resulted in enhanced major nutrient
drawdown. Our observations thus suggest that the 2010 Eyjafjallajökull
eruption resulted in a significant perturbation to the biogeochemistry
of the Iceland Basin.
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