IMHO the significance of the silicic acid would depend on the time of
year. In the spring silicic acid is generally abundant so adding more of
it would make little difference. One it has all been used up and diatoms
are giving way to other phytoplankton a boost of silicic acid would give
rise to a second diatom bloom - so it would be very significant. And of
course the other question is how effectively the chemical composition of
the silicate in the ash and its particle size as this will determine its
quality as a source of silicic acid.
Have the authors given any serious examination to such questions? Oliver.
On 21/08/2013 09:55, Chris Vivian wrote:
Oliver,
I have seen the paper but cannot post a copy online. In the paper the
authors did measure the release of nitrate, nitrite, ammonia,
phosphate and silicate in leaching experiments and concluded that the
impact of these macronutrients released from Kasatochi ash on primary
productivity was probably minimal. They also suggested that the
release of trace metals other than iron could also have influenced
phytoplankton growth.
Chris.
On Monday, August 19, 2013 4:23:59 PM UTC+1, Oliver Tickell wrote:
I have not found an open source version of this paper yet, but
here is a related one.
http://www.biogeosciences.net/10/3715/2013/bg-10-3715-2013.pdf
<http://www.biogeosciences.net/10/3715/2013/bg-10-3715-2013.pdf>
They do recognise that diatoms need silicic acid but do not seem
to have thought of volcanic ash as a source of silicic acid, only
of iron.
Re olivine application, it is worth noting that olivine is a
mixture of Mg silicate and Fe silicate. Some proportion, to be
determined, of the iron in olivine will become bioavailable as
weathering progresses.
Oliver.
===============
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. Patsch ¨
2
, I. Lorkowski2
, and M. Hort1
1
Institute of Geophysics, KlimaCampus, University of Hamburg,
Hamburg, Germany
2
Institute of Oceanography, KlimaCampus, University of Hamburg,
Hamburg, Germany
Correspondence to: B. Langmann ([email protected] <javascript:>)
Received: 29 June 2012 – Published in Biogeosciences Discuss.: 26
July 2012
Revised: 18 April 2013 – Accepted: 8 May 2013 – Published: 5 June 2013
On 19/08/2013 15:03, Oliver Tickell wrote:
This is very odd. Based on the abstract only (article behind
paywall) it appears that they attribute the diatom bloom to iron
fertilisation. Oddly they have not considered the role of silicic
acid from the dissolution of Mg silicate species in the finely
powdered volcanic ash. Silicic acid is often the limiting
nutrient for diatoms, as they use it to make their silica shells.
There is ample geological evidence of diatom (specifically)
blooms being associated with falls of volcanic ash.
Is anyone able to post the actual article? Oliver.
On 17/08/2013 17:13, Wil Burns wrote:
FYI. wil
MEPS - Vol. 488 - Table of contents
<http://www.int-res.com/abstracts/meps/v488/>
*Mar Ecol Prog Ser (Print ISSN: 0171-8630; Online ISSN: 1616-1599)*
Copyright © 2013 Inter-Research. Published August 15
*Olgun N, Duggen S, Langmann B, Hort M, Waythomas CF, Hoffmann
L, Croot P *
Geochemical evidence of oceanic iron fertilization by the
Kasatochi volcanic eruption in 2008 and the potential impacts on
Pacific sockeye salmon
MEPS 488:81-88
<http://www.int-res.com/abstracts/meps/v488/p81-88/> | Full text
in pdf format
<http://www.int-res.com/articles/meps2013/488/m488p081.pdf>
--
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Master of Science - Energy Policy & Climate Program
Johns Hopkins University
1717 Massachusetts Avenue, NW
Room 104J
Washington, DC 20036
202.663.5976 (Office phone)
650.281.9126 (Mobile)
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