Thanks! My last sentence should have read "And of course the other
question is re 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." So you understood.
the rate of weathering is proportionate to surface area so small
particles are hugely more effective at releasing silicic acid than large
ones. Olivine grain sizes of 0.1mm are proposed for terrestrial
application and far smaller than this (~ micrometre scale) for marine
use so that the particles can weather during their residence in the
water column. The 'powdery' fraction of the ash will give the greatest
silicic acid contribution.
It's hard for me to comment further without seeing the paper but it's
good to know that these questions have been considered, Oliver.
On 21/08/2013 15:05, Chris Vivian wrote:
Oliver,
Bear in mind that the North East Pacific is a high-nutrient,
low-chlorophyll (HNLC) area that is known to be limited by iron. The
paper gives estimated sea water concentrations of silicate in the
North East Pacific in the top 20 metre mixed layer in August 2008 when
the volcanic eruption occurred of 5,000-15,000 nM (nana molar)
compared to an estimated 6-20 nM supply from the ash fallout over the
fertilized area in the Gulf of Alaska.
Your second point was unclear but I assumed you were querying the
release rate of the silicate from the ash. The ash used in the
experiment was collected on a fishing boat during the eruption and
stored dry in containers. The experiment only used the < 2 mm size
fraction. The release rate of silicate in the experiments was 170 nmol
silicate per gram of ash in the first hour and up to 585 nmol silicate
per gram of ash after 20 hours.
Chris.
On Wednesday, August 21, 2013 10:12:19 AM UTC+1, Oliver Tickell wrote:
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])
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>
--
Dr. Wil Burns, Associate Director
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)
[email protected]
http://advanced.jhu.edu/academic/environmental/master-of-science-in-energy-policy-and-climate/index.html
<http://advanced.jhu.edu/academic/environmental/master-of-science-in-energy-policy-and-climate/index.html>
SSRN site (selected publications):
http://ssrn.com/author=240348
�
Skype ID: Wil.Burns
Teaching Climate/Energy Law & Policy Blog:
http://www.teachingclimatelaw.org
<http://www.teachingclimatelaw.org>
--
You received this message because you are subscribed to the
Google Groups "geoengineering" group.
To unsubscribe from this group and stop receiving emails
from it, send an email to [email protected].
To post to this group, send email to
[email protected].
Visit this group at
http://groups.google.com/group/geoengineering
<http://groups.google.com/group/geoengineering>.
For more options, visit
https://groups.google.com/groups/opt_out
<https://groups.google.com/groups/opt_out>.
--
You received this message because you are subscribed to the
Google Groups "geoengineering" group.
To unsubscribe from this group and stop receiving emails
from it, send an email to [email protected].
To post to this group, send email to
[email protected].
Visit this group at
http://groups.google.com/group/geoengineering
<http://groups.google.com/group/geoengineering>.
For more options, visit
https://groups.google.com/groups/opt_out
<https://groups.google.com/groups/opt_out>.
--
You received this message because you are subscribed to the
Google Groups "geoengineering" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected] <javascript:>.
To post to this group, send email to [email protected]
<javascript:>.
Visit this group at http://groups.google.com/group/geoengineering
<http://groups.google.com/group/geoengineering>.
For more options, visit https://groups.google.com/groups/opt_out
<https://groups.google.com/groups/opt_out>.
--
You received this message because you are subscribed to the Google
Groups "geoengineering" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/geoengineering.
For more options, visit https://groups.google.com/groups/opt_out.
--
You received this message because you are subscribed to the Google Groups
"geoengineering" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/geoengineering.
For more options, visit https://groups.google.com/groups/opt_out.
