- Occasional poetry No.4
-
Pillars of Salt (excerpt)
We always look back,
attracted by that feeling
of having been there before – the roads
sinking, the soil weeping (scab on scab
lifted), fences sunk to gullies
catching the garbage of paddocks,
strainers blocked by stubble
and machinery and the rungs
of collapsed rainwater tanks / and maybe
the chimney and fireplace
of a corroded farmhouse, once
the guts of the storm, now
a salty trinket.
© 2003, John Kinsella
From: Peripheral Light: Selected and New Poems
Publisher: Fremantle Arts Centre Press, Fremantle, 2003
ISBN: 1 86368362 3
Read the entire poem at http://australia.poetryinternationalweb.org/
Image from www.agric.wa.gov.au
- Next journal club meeting - carbon in China
-
The next meeting (already notified by Talitha) is on Tuesday 7 July, 1pm, second-floor lunch area, Soil Science building, UWA.
The article to be mused upon is :
Piao S, Fang J, Ciais P, Peylin P, Huang Y, Sitch S, Wang T. 2009. Carbon balance of terrestrial ecosystems in China. Nature, 458:1009-1014.
- Astonishing reasoning on Greenland from U.S. scientists
-
The good news (for some of the approximately 57,600 Greenlanders, at least): Greenland now has much more control over its destiny, following the decision from Denmark to allow self-rule for Greenlanders (see the article at the Sydney Morning Herald).
The not-so-good news: the following excerpt from this, and other, articles on this event is a real jaw-dropper:
"US scientists believe Greenland's northern tip is especially rich in
oil and gas and they say global warming could help unlock the untapped
wealth under the ice-cap and provide a solid foundation for an
independent economy."
Let's just hope that these are the same ubiquitous and apocryphal "U.S. scientists" who seem to crop up occasionally in news articles to justify not-to-be-disputed points of view. Let's also hope they have sufficient integrity to be greenhouse sceptics.
It's hard to imagine a more cynical and blithely pragmatic approach to the issue of global warming, whether or not one has doubts about the anthropogenic hypothesis (which would be too large a can of worms ever to be opened on this blog).
Image from cartophilia.com
- Small data set, high impact
-
[Musings by Talitha Santini]
The first
article for the revived Journal Club was ‘Jarosite as an indicator of
water-limited chemical weathering on Mars' (Elwood Madden et al. [2004] Nature, 431:821-823), chosen by Talitha because it was a short and
reasonably simple article about soils on another planet. The authors used
observations of jarosite and gypsum as alteration products of the basaltic
parent rock at the Meridiani Planum landing site on Mars to argue a case for
chemical weathering on Mars being water-limited. Using geochemical modelling
software, a basaltic mineral assemblage (using data from Rosenbauer
et al. [1983]) was titrated into a fluid containing SO42-,
Na+, K+, Ca2+, Fe2+, Mg2+,
Al3+, and dissolved SiO2, under current Martian
atmospheric O2 and CO2 fugacities, at 298 K and 104Pa
total atmospheric pressure. The authors modelled both mineral assemblages as
basalt weathering progressed, and the final mineral assemblages at different water:rock
ratios. Modelling indicated that jarosite could only be present as a result of
basalt weathering if (a) a large quantity of water reacted completely with a
small amount of rock (for example, water creating an alteration rind on rock
surfaces); or (b) a small amount of water reacted only partially with a large
amount of rock. It was concluded that once jarosite formed, water must have
been removed quickly in order to halt chemical weathering before pH increased
and jarosite was converted to an iron (oxy)hydroxide - hence the article's
title.
Once we
started examining the article, we realized how little data were required to have
an article published in Nature. The
authors used only five pieces of information about Mars (the presence of a
basaltic parent rock, the presence of jarosite and gypsum, and Martian
atmospheric O2 and CO2 fugacities and atmospheric
pressure) and a geochemical model designed for Earth surface conditions. This
got us thinking about having a look at some Martian soil
data from NASA (presented in Rieder et
al. [1997]) and publishing our own articles. It's a good example of
researchers considering data critically and extracting as much information as
possible with the tools they have available to them. The tools we have
available aren't perfect though, and one of the criticisms of this article was
the ‘Earth-centric' modelling - that is, the use of Earth surface conditions to
simulate Martian weathering processes. Where possible, the authors used
(current) Martian conditions; however, in the case of temperature and pressure,
current Earth conditions were used.
The ‘suppression of mineral phases...at the
discretion of the operator' also raised debate about using geochemical
models to simulate weathering. The problem is that models generally predict
phase assemblages at thermodynamic equilibrium, which may not actually occur in
the field. The authors cite the example of slow goethite formation hindering
its occurrence in acid mine drainage environments despite being the
thermodynamically stable iron phase. Kinetics were only included in this model ‘through the suppression of mineral phases unlikely to form in a geologically relevant time period.'
So why should we care about soils on Mars, anyway? We came up with a few answers to
this: for the pure basic science objectives of understanding the properties and
history of Martian surface materials and understanding how soils develop under
different environmental conditions; because soil on another planet is
inherently interesting; and because we may even want to annex Mars one day as a
replacement Earth, in which case an understanding of its soils would be pretty
important.
The next article will be chosen by Bree, with the next meeting scheduled for July
1.
Image from www.andersonfreepress.net
- I feel good, I feel stupid
-
This was something I sent around to our School's postgraduate students, after being sent the article by Prof. Martin Fey:
Schwartz, M.A. (2008) The importance of stupidity in scientific research. Journal of
Cell Science121:1771 .
This
should be essential reading for postgraduate students in any
discipline. (It's irrelevant that it's in a
biology journal.) Essentially Schwartz's argument is that since research is on the very edge of human knowledge, feeling lost or stupid should be felt regularly by researchers. This normalisation of the self-doubt that many of us feel (and not just while doing our graduate research!) is surprisingly encouraging.
"...we don’t do a good enough job of teaching our students
how to be productively stupid – that is, if we don’t feel stupid it
means we’re not really trying."
It's great to see articles in scientific journals that acknowledge the humanity of researchers.
Image from www.cartoonstock.com
- time for a little poetry
-
|
Christopher James
We buried him with a potato in each hand
on New Year’s Day when the ground was hard as luck,
wearing just cotton, his dancing shoes plus
a half bottle of pear cider to stave off the thirst.
In his *** pocket
we left a taxi number
and a packet of sunflower seeds; at his feet was
the cricket bat he used to notch up a century
against the Fenstanton eleven.
We dropped in his
trowel and a shower of rosettes
then let the lid fall on his willow casket.
The sky was hard as enamel; there was
a callus of frost on the face of the fields.
Dust to dust; but
this was no ordinary muck.
The burial plot was by his allotment, where
the water butt brimmed with algae and the shed door
swung and slammed as we shook back the soil.
During the service,
my mother asked
the funeral director to leave; take away some hair
and the resemblance was too close; and yet
my father never looked so smart.
I kept expecting him
to walk in, his brow
steaming with rain, soil under his fingernails
smelling of hot ashes and compost;
looking for fresh tea in the pot.
©
2009, The Poetry Society
Publisher: The Poetry Society (website), London, 2009
|
 One
of an occasional series of poems (this is No. 3) selected simply because they mention
the word 'soil'.
In
this poem soil helps to signify death, most likely drawing from the biblical
creation story:
"By the sweat of your brow you will eat your food until you return to the ground, since from it you were taken; for dust you are and to dust you will return." (Genesis 3:19)
The
second mention of soil perhaps tells us about the character of the dead
man; earthy, with few pretensions.
But
never mind the references to soil, and biblical allusion - it's a beautiful
poem.
|
- Journal club revived
-
[Edit at 29 May 2009 - the date has been shifted to Wednesday 3 June]
The poster at right was prepared by Talitha to publicise the first meeting of the Soil Science Journal Club for 2009...
...we'll be discussing the article: Madden MEE, Bodnar RJ, Rimstidt JD. 2004. Jarosite as an indicator of water-limited chemical weathering on Mars. Nature, 431:821-823.
Maybe we'll see you there?
[The second-floor lunch area is on the top floor of the School of Earth & Environment (South) building (i.e. the Soil Science building).]
- Renewable energy
-
It may be that we see a bit more activity on this blog, following Talitha's suggestion to crank up the old-style journal club. That is, a club with more than one person in it, who actually read and discuss journal articles, and post their musings on this site (formerly created for that very purpose).
I'd be very keen on this sort of development, particulary as I thought I heard an offer for participants to take charge of at least some of the selection of articles and the blogging. As Talitha put it, a bit like a book club, but with less reading. Less work for me? - sounds very worthwhile.
Partly, this springs from my newly acquired role as one of the Graduate Research Coordinators in the School of Earth and Environment. Lots of this role is administrative, to be sure, but the opportuntity to interact with many of the School's motivated and scarily smart graduate research students is inspiring (and a lot of fun).
(Image from www.hardbacker.com)
- Urban Soils
-
The journal Urban Ecosystems has just published a Special Issue on Soils. As our planet and its human populations become increasingly urbanised, this would seem to be a growth area for the earth and ecological sciences.
Some of the articles from this issue of the journal:
I'm definitely looking forward to reading some of these.
- Science and sustainability
-
A recent article in Environmental Science and Technology identifies scientific facilities as high energy users.
University sustainability, as rightly pointed out by Sky elsewhere in myResearchSpace ("A Sustainable Campus"), commonly focuses on 'green' or ecological issues . Dr Mills makes the point that "much can be done to enhance sustainability within the scientific enterprise itself". The diagram at left, from Mills' article, suggests that the practice of science can result in comparatively high energy usage.
The main contributors to high energy use are identified as laboratories, computing, and clean environments.
Mills goes so fas as to suggest that sustainability, or at least energy usage, issues should be amongst the criteria against which research grants are assessed (pity the poor folks in space research).
It would definitely be interesting to analyse the energy use of earth science projects. Many (especially involving remote area or ocean travel, drilling or remote sensing) could come in fairly high.
Image from pubs.acs.org
- Cleaning your bathroom with soil science
-
I was very proud of myself in the weekend. Some time after renovating our bathrooms at home, we found brownish water stains on the otherwise glossy white acrylic vanity tops. Not a good look. Guessing that these were some sort of iron oxide precipitate, I suggested that my wife try a mixture of lemon juice and baking soda on the stain. As you might expect, this was based on a re-interpretation of a commonly used method for selectively dissolving iron oxides in soils, the DCB (dithionite-citrate-bicarbonate) method. The basis of the method was first published by Mehra and Jackson in 1960; I'm more familiar with the method instructions in Loeppert and Inskeep (1996).
To dissolve iron oxides efficiently your [cleaning] solutions needs to have three key properties:
- something to reduce Fe3+ to Fe2+
- something to form a complex with Fe2+
- a buffer to keep the pH high enough.
In Mehra and Jackson's method 1.=dithionite, 2.=citrate, and 3.=sodium bicarbonate. Fortunately this can be approximated using household ingredients. In the lemon juice / baking soda system, the reducing agent (1.) is the ascorbic acid (vitamin C!) in the lemon juice (dithionite is kind of nasty to handle anyway); the lemon juice is also a good source of citric acid (2.). Baking soda is sodium bicarbonate (3.), so no substitution problems there. We applied the mixture to the stain, left it for a moment, and scrubbed with an old toothbrush. Better than abrasive cleaners on an acrylic vanity top, and the stain was completely removed!
I've used adaptations of this method successfully before to remove iron stains from kettles (half a lemon and a teaspoonful of baking soda in the kettle; fill with water, boil, discard, and rinse) and toilets (similar to kettles, but you'll need to add hot water to the bowl...)
Literature
Loeppert, R.H. & Inskeep, W.H. (1996). Iron. In Methods of Soil Analysis. Part 3 - Chemical Methods. (Eds D.L. Sparks, A.L. Page, P.A. Helmke, R.H. Loeppert, P.N. Soltanpour, M.A. Tabatabai, C.T. Johnston and M.E. Sumner) pp. 639-664. (Soil Science Society of America: Madison, WI, USA).
Mehra, O.P. & Jackson, M.L. (1960). Iron oxide removal from soils and clays by a dithionite-citrate system buffered with sodium bicarbonate. In Clays and Clay Minerals, Proc. 7th Natl. Congr.; Pergamon, London.
P.S. If you're sensitive about such things, it's usually me who cleans the bathrooms in our house. I was redecorating the bedroom at the time...
Soil image from www.agric.wa.gov.au
- Digging for gold
-
Musings on:
Anand RR, Cornelius M, Phang C, 2007. Use of vegetation and soil in mineral exploration in areas of transported overburden, Yilgarn Craton, Western Australia: a contribution towards understanding metal transportation processes.Geochemistry-Exploration Environment Analysis, 7: 267-288.
The use of soils and vegetation as sample media for geochemical exploration is not new. In recent years there seems to have been a resurgence of interest in sampling soils, and particularly plants, with the expectation that these media carry a signature of underlying ore bodies. In many cases the rock or regolith which hosts the ore body may be masked by transported sediments, so that even the weathered ghostly imprint of an ore may lie well below the surface.
Several mechanisms may allow the formation of signatures of ore bodies in surface soils, even in a transported overburden. In addition to purely chemical or physical processes, it is possible that plants can access ore-forming elements at depth, as deep roots search the regolith for water. Not only can this give anomalous concentrations of trace elements in plant tissues, but biological re-cycling can subsequently enrich surface soils with a signature of what lies beneath.
These ideas are the basis for Anand et al's. article. They took vegetation (mulga; Acacia aneura and related species) and soil samples across known but unexploited gold and/or base-metal (Cu, Zn, Ag) deposits in Western Australia, where much of the bedrock is covered by deeply weathered regolith profiles and, in many cases, transported sediments as well. They found that analysis of soils did not clearly delineate the vertical projection of underlying ores (even using selective extractions for trace elements which commonly improve signal:noise ratios). In contrast the living plant tissues, and particularly the litter layer, showed clear signatures of underlying mineralization, with peak concentrations in both media vertically over the ore body.
These results are of obviously practical importance to exploration geochemists, demonstrating that (at least in some instances) vegetation sampling and analysis offers an additional tool to "see through" weathered and/or transported material to ore bodies beneath. It is possibly more generally significant, from an "understanding the Earth" point of view, that vegetation may be important in redistributing trace elements in earth surface environments, particularly in arid regions where plants' search for water requires root growth to great depth. In such environments, geochemical signatures in soils may well be the result of millennia of plant uptake.
Image of the Moolart Well prospect from www.regisresources.com
- New Comment on A Soil Scientist's Lament
-
A new Comment has been posted in reply to A soil scientist's lament, by Professor
Philippe Baveye (the author of the article mused upon in the original post).
It's well worth reading. You can get to it by clicking here, too (scroll down to the bottom of the page).
- the soil on Mars
-
...musings on Amundson R, Ewing S, Dietrich W, Sutter B, Owen J, Chadwick OA, Nishiizumi K, Walvoord M, McKay C. 2008. On the in situ aqueous alteration of soils on Mars. Geochimica et Cosmochimica Acta 72:3845-3864.
It's great when an article related to one's own discipline is about something exotic, and it would be hard to imagine a more exotic environment than the surface of Mars. I enjoy highlighting interesting developments to students, so this year's Introduction to Geochemistry students had the data from this article as an example when we learned about mass balance during weathering. And this was my first crack at teaching this geochemical topic to students as well, so I learned a lot too. We used the subject matter, if not the Martian data, in a prac class, using an excellent dataset published by Oh & Richter (2005).
Amundson et al.'s hypothesis is that liquid water must have existed on Mars at some stage in that planet's history, based on the mineralogical record (minerals which need water to form, such as smectites and jarosite, have been identified on the Martian surface). Amundson et al. further tested this hypothesis by using elemental analysis data from conveniently exposed "soil profiles" on Mars, within the Gusev and Endurance craters investigated by the Mars Exploration Rover (Opportunity) mission. They were looking for evidence of absolute loss or gain of elements which might reflect transport by liquid water - and they found exactly that. Soils were depleted in major rock-forming elements (Si, Al, Mg, Ca, Fe, etc.) relative to the likely parent materials (Gusev basalt, or aeolian dust), probably representing earlier weathering mediated by water. A key result was the enrichment in the soil profiles of sulfur, chlorine and bromine, consistent with the aqueous transport of sulfate, chloride and bromide salts followed by drying.
The point is also made that comparable environments (very dry and cold; e.g., some of Antarctica) exist on Earth, and similar soil-forming processes have occurred here (on Earth, that is!) as well. The authors refer to such terrestrial soils as being "abiotic"; a bit of a misnomer, I thought, where perhaps they meant the absence of higher organisms (surely some microorganisms were present in all the Earth examples - were they there on Mars?). Plus there is the usual issue with mass-balance approaches (fully acknowledged) of matching the weathered/altered material to its assumed parent material.
This was a fun article to read. It's not often that I get to read and use a publication that contains so much language usually reserved (in my reading experience) for science fiction - Mars landers, differences in gravity - all wonderful stuff.
Image from www.nasa.gov
- A good excuse for not posting
-
I've been doing a lot of marking lately, and not much else, it seems. Certainly no blogging for weeks, sadly.
The reason is my experience of one of the less salubrious hazards of cycling to work; about a month ago I came off second-best in a bingle with a car at a roundabout. I like cycling; it keeps me fit, reduces my carbon footprint and saves me money. But a split second of bad timing, and I end up with an AC joint dislocation (see image at right, with my cyborg implant at bottom so the ligaments can grow back together), and four broken ribs. Could have been worse, probably; in a perverse sense, I'm lucky.
The ability to work from home has been a godsend. My indispensable colleagues have had to pick up what lectures remained in the last weeks of semester, and I've been churning away when I can at marking assignments, lab reports and so on. Next stop exam papers, a PhD thesis to examine, and several ARC proposal assessments - all classifiable under 'marking'. It's surprising to think how much time academics spend on assessing others' work. It could go on all year...