Silent witnesses

How geochemistry tells about climate and environments

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Temperature reconstructions with earthworm calcite

My poster of last Wednesday



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A tourist in Florence

The birth of Venus - Sandro Botticelli c. 1486

The birth of Venus – Sandro Botticelli c. 1486

After four days of Goldschmidt 2013 my brain had reached geochemistry saturation state, so I figured it was time for some tourism. Earlier this week I had only ventured into the city in the early morning, and I only now realised how peacefully quiet it had been. Florence is a virtual ants nest of tourists and the people trying to sell them things; not my favourite habitat.

I did manage to get a ticket for the Uffizi Gallery without too much queueing and spent a while looking at beautiful and some famous paintings such as “The birth of Venus and four portraits by the Dutch 17th century master Rembrandt van Rijn. Of course I had to see the Museo Galileo as well. Lots of fascinating scientific instruments, globes, clocks and what have you. Too bad they didn’t sell any replicas in the museum shop.


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The early bird catches the worm

The "terror bird" Gastornis (

The “terror bird” Gastornis (

For many of us being an early bird becomes progressively more difficult as conference fatigue takes its toll. I was glad to see a sizeable crowd managed to be there for the start of our session on the role of biominerals in biogeochemical cycling, which happened to be about birds and worms, and some other creatures.

Thomas Tütken showed us that the fearsome Eocene terror bird was neither a predator, nor a worm-catcher, but a gentle herbivorous giant instead! Also, the oxygen isotope composition of the bones of large herbivores forms a remarkably good archive of Cenozoic climate, agreeing well with the famous Zachos curve.

Then it was my turn to talk about worms, who are unexpected biomineralisers, and appear to precipitate atmospheric carbon dioxide in carbonate granules in the soil. Loredana Brinza studied metals in these granules, and demonstrated that they can significantly contribute to zinc immobilisation in polluted soils.

From animals we switched to plants, with two presentations about phytoliths: little chunks of silica produced by plants. Jean-Dominique Meunier and Eric Struyf showed that the contribution of phytoliths to global silicium cycling is much larger than previously thought and is of the same order of magnitude as the marine contribution of diatoms. Humans remove a lot of silicium from the global cycle by harvesting crops, and this likely reduces crop yields.

Going from the terrestrial to the marine realm, Ruth Carmichael spoke about nitrogen in bivalves and their potential for nitrogen sequestration as well as reconstruction of nitrogen cycling before human influences, using shells from middens that are thousands of years old. Adilah Ponnurangam stayed with the bivalves, but looked at rare-earth elements and showed that they reflect seawater composition.

The session ended with Michaël Hermoso presenting some meticulous laboratory culture experiments on coccolithophores, and size-related differences in carbon-isotope fractionation. All-in-all a very interesting morning, and a satisfying debut as a session chair.

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Things I learned today

Entrance Triple oxygen isotope compositions of dinosaur egg shells can be used to reconstruct past atmospheric carbon dioxide levels.

Four different geochemical societies were incapable of finding a single woman to award any of their ten prestigious medals to.

Copper and iron isotopes vary with AB0 blood types.

Copper isotope values in blood are a more reliable marker for cancer severity than currently used antigens.

The top half of most sapropels has vanished due to progressive top-down oxidation.

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Palaeo-proxies and trophic positions


I like it when people show how a proxy works, or how it doesn’t. Today at Goldschmidt I enjoyed several presentations doing exactly that. The day started with Johanna Noireaux showing that boron isotopes can only function as a pH proxy in aragonite, and not in calcite.

Anders Meibom presented work by Nehrke et al. demonstrating that contrary to what is commonly thought, foraminifera do not form most of their shell calcite from seawater that is ingested in vacuoles, but by active transport of calcium across the cell membrane. Vacuolisation does explain the presence of magnesium in foraminifera calcite, and also that the amount of magnesium is different between species, and depends on temperature (hence it’s such a good proxy).

Something else I’ve been keen to learn more about, is specific compound stable isotope applications. Yoshito Chikaraishi gave a very clear presentation showing that when bulk carbon and nitrogen isotope compositions look kind of messy, the compositions of specific amino acids can actually give us an accurate picture of the structure of a food web.

Geochemists’ second love (after geochemistry of course), must be food & drink. Apart from learning about trophic positions of various organisms, importantly we learned that a lot of the animals studied make excellent sashimi. When this afternoon I heard a speaker explaining the location of their sampling site mostly in relation to a BBQ restaurant, I knew it was almost time for beer and snacks, and posters.

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Introducing the Bloggers of Goldschmidt 2013

It isn’t long until the start of the annual V.M. Goldschmidt conference, the main international meeting for geochemists to share and discuss ideas. This year’s meeting in Florence, Italy, is set to be one of the largest yet with over 4000 abstracts submitted. The European Association of Geochemistry and the organisers of this 23rd Goldschmidt meeting have assembled a team of writers from the geoblogosphere to cover the science and social activities of the conference. Here is that team, meet Andy, Betsy, Emma, Matt and Simon. Follow our coverage of Goldschmidt 2013 here on the EAG blog and on twitter, using the #Goldschmidt2013 hashtag.

Andy BrayAndy

University of Leeds, UK

I’m a Ph.D. candidate working in Cohen Geochemistry,School of Earth and Environment, University of Leeds, investigating the processes and rates of mineral weathering by soil dwelling micro-organisms. Generally, I’m interested in anything that involves life interacting with rock. That covers things from micron scale biogeo interactions, contaminant geochemistry, Critical Zone processes, global (bio)geochemical cycling and even a bit of astrobiology. In addition to my oral presentation (Thursday 16:45, 10j), I’ll be attending sessions with bio-geo themes and writing on some of the interesting presentations I see. I’m relatively new to blogging and alongside helping to set up the Cohen Geochemistry Users’ Blog, I (sporadically) post articles on the EAG Blog and Tumblr. I will be tweeting throughout Goldschmidt and you can follow me @Brayaw. Come and find me in Florence and talk to me about science or tell me a bad joke, either way I’ll enjoy it. See you at the icebreaker!

BetsyBetsy Swanner

University of TübingenGermany

Greetings from Tuebingen where I am busy preparing for this year’s Goldschmidt meeting. It will be my fifth trip to Goldschmidt, and is always one of the highlights of my professional year. It is however, my first experience as an official blogger, but I have gained some experience writing for the EAG Blog already this year. One of the aspects I am looking forward to most is convening a session for the first time – Session 9e: “Life in ferruginous settings: building the bridge between sedimentology and geomicrobiology”. You can find me at our posters on Wednesday afternoon (164 to 169) and the orals on Thursday afternoon (L05), along with co-conveners Nicole Posth of NordCEE-University of Southern Denmark and Bertus Smith of the University of Johannesburg. I will also be presenting my current postdoctoral research, which investigates the impact of Archean levels of dissolved iron on the growth of a marine cyanobacterium (Session 19e: Phototrophic Life and Earth’s Redox Evolution). See you in Florence! 

Emma VersteeghEmma

University of Reading, UK

I’m a post-doc working at the Department of Geography and Environmental Sciences, University of Reading. My current research focuses on carbonates produced by earthworms, and if they can be used as a proxy for past climate and environments. My broader interests range from stable isotope chemistry to marine ecology, palaeoclimatology and archaeology. Although I have written some short entries on my own blog Silent Witnesses and occasionally tweet as@emmaversteegh, this is the first time I’m having a go at blogging for a conference. Quite exciting! It is also the first time I’m convening a session, with my PI Mark Hodson: 19j The Role of Biominerals in Biogeochmical Cycling, in which Mark will present some of our recent findings on the role of earthworm-produced calcium carbonate in the terrestrial carbon cycle. I will present a poster on Wednesday on Pleistocene and Holocene Temperature Reconstructions Using Earthworm-Produced Calcite. I’m very much looking forward to Goldschmidt 2013 and hope to meet many of you there. 

MattMatt Herod

University of OttawaCanada

I am Ph.D. Candidate working with Dr. Ian Clark in the Department of Earth Science at the University of Ottawa. My research focuses on the environmental geochemistry of iodine and the radioactive isotope iodine-129. This work involves characterizing a 129I baseline in the Canadian Arctic and applying this to the transport and sources of 129I to remote regions as well as to long term radioactive waste disposal. I also work on the transport and fate of 129I from the Fukushima Daichii Nuclear Accident. At this Goldschmidt I’ll be found in aqueous and isotope geochemistry sessions listening to all of the great work that has been going on, and blogging about what I learn at my EGU network blog,GeoSphere. I’ll also be tweeting as @GeoHerod. My own talk is in session 18j: Geochemical and Biological Fate of Anthropogenic Radionuclides. I’ll be speaking on Thursday afternoon about my work on the rainout of 129I from Fukushima and its transfer into groundwater on the west coast of Canada. Hope to see you in Florence!! 

Simon RedfernSimon

University of CambridgeUK

I’m a Mineral Physicist, which means I enjoy applying an understanding of the properties of Earth materials at the atomic scale to a wide range of problems across Earth’s history, on global scale. By studying interactions across varying length scales and time scales I aim to understand how our planet works. I will be talking at Goldschmidt on Monday afternoon, about how synchrotron X-rays can be used to image the geochemistry of plankton calcite shells at the nanoscale. This year I have enjoyed a stint as a British Science Association media fellow, which has involved working at the BBC Science & Environment desk learning about science communication, and I also blog on the EGU network. All this activity started as blog at Geopoem for my students, and I post things there still. I’ll be tweeting, when I have a moment, as @Sim0nRedfern.

We’re aiming to provide a wide coverage of Goldschmidt 2013 via our blogging and tweeting, but make sure you also keep an eye out for the official press releases coming throughout the week.

(re-posted from