Géoblog

Category: A researcher’s day

How does day-to-day research work? Discover its wonders and challenges: stories of fieldwork adventures, of surprises in the laboratory, thrilling investigations or actions unheard of, that are key to the progress of a research project. Share the doubts and discoveries of the researchers!

  • Toward inclusive fieldwork: A handbook in the making

    Toward inclusive fieldwork: A handbook in the making

    Floreana Miesen is a field technician, involved in a variety of field projects at the Institute of Earth Surface Dynamics (IDYST). Natalie Emch is Equity, Diversity and Inclusion (EDI) officer at the Faculty of Geoscience and the Environment. Through their involvement in this working group, both would like to ensure fieldwork would be a positive learning and professional experience for all. Three other people are actively working in the group: Prof. Georgina King, Dr Ian Delaney and Léa Rodari.

    Fieldwork constitutes a crucial element in teaching and research within Geography and the Earth and Environmental Sciences. It has a pivotal role in shaping a student’s career trajectory and for accomplishing research objectives. Recognizing its significance has raised the following concern: how can we make fieldwork as inclusive and accessible as possible? In a collaborative effort to address this issue, Floreana Miesen and Natalie Emch are actively engaged in a working group tasked with crafting a toolkit to help make fieldwork more accessible. The aim is to come up with solutions that respond to the various needs, by involving the entire student and research community in the reflection process.

    Can you say more about this working group “A good practice guide for fieldwork”?

    N.E : The working group endeavors to collect input and advice from members of the FGSE across different perspectives and institutes. Our aim is to produce a Handbook of Good practice – a useful resource for both teaching staff and students. It will be a support document for preparing and organising any type of field camp, whether for teaching or research purposes. Unlike a set of rigid rules or directives, the Handbook aims to inspire and guide. It will cover aspects such as communication, sanitary installations, accessibility to material to give some examples. We would like the community to know there is a support structure at the faculty to address these challenges related to fieldwork.

    What will be the content of this handbook?

    F.M. :  The document is structured around simple questions for teaching staff and participants. They encompass safety and well-being issues. For examples: “Have the participants been informed about the daily schedule, the mobile phone network coverage, local customs…?” – “Have participants been informed of the equipment to bring and how to obtain it?” – “As a participant, am I uneasy about an issue I wish to raise with the organisers? Is there any constraints I could to share with the organisers, such as family care responsibilities?”

    The important point is to foster timely communication and open dialog between organisers and participants. This initiative seeks to raise awareness about the fact that students may not dare to express significant concerns, such as safety and personal needs. It’s central to avoid assuming that everyone has a sleeping bag, has been to the mountain tops or is free of family duty.

    “The aim of the document is to remove barriers that can hinder or prevent participation and learning, and to create safe and pleasant conditions for everyone.”


    Floreana Miesen

    Work in progress – your input is welcome!

    You are a student, a teacher, a researcher at the FGSE and wish to share your experience on the field? Or do you simply want to know more? Feel free to contact the working group ce-fgse@unil.ch.

    We are still collecting input from different perspectives and across the three FSGE institutes. For instance, we welcome suggestions about:

    • What type of support is needed to organise a successful field camp? (Training in conflict management, in how to deal with anxiety…?)
    • As a participant, what information do you need to prepare a field camp with confidence?

    Why this project for a good practice guide?

    N.E. : UNIL is committed to improve the well-being of its members and the inclusion of people, regardless of their gender, ethnic or migratory background, disability… This work is hence a contribution to UNIL’s ambition to fight inequality. Issues of safety and personal integrity in the field are part of UNIL’s action plan for equality, diversity and inclusion, and our working group is part of this commitment.

    “When people feel safe, respected, valued, supported, they are able to actively contribute.”

    Natalie Emch

    Natalie Emch, why is this project important to you?

    N. E. : When I arrived in 2022, a workshop had just taken place at FGSE with Ann Rowan (University of Bergen, Norway) (March 2022), which addressed the question of inclusivity in fieldwork.  Feedback from the students highlighted that fieldwork was highly valued, as it enabled them to acquire scientific and practical know-how that was distinct from that of the classroom.

    However, some students highlighted their anxieties, their specific needs and lack of clarity around responsibility and field conditions which can interfere with their learning. We observe that due to hierarchical structures and the fact that students are evaluated they can feel shy to speak up.

    This led to the decision to create a working group to address this issue and develop a handbook for good practices. As the EDI officer of FGSE, I have embraced this project and I hope this work will attract more diversity in the field.

    For Floreana, field work is an opportunity to see and feel the study landscape. (Photo: Nikola Schulte-Kellinghaus)

    Floreana Miesen, why is this project important to you?

    F. M.: I enjoy everything related to fieldwork. During my studies in Geography in Germany, I had the opportunity to participate in a lot of field courses and field research. I felt it really was one of the best ways to learn. Fieldwork was my motivation to apply for this position at IDYST. I still appreciate the variety of projects and approaches in the field.  However, I have noticed that students sometimes face challenges. For example, they can feel overwhelmed by the gap between their experience of hiking with friends and the demands of working in mountainous terrain.

    I am convinced that to focus on the learning objectives, students should not be preoccupied with managing challenges related to personal needs exacerbated by a field course. By addressing issues – like physical fitness requirements, personal constraints or financial limitations – this handbook proposes strategies to lower entry barriers. 

    “I would like to convey my enthusiasm for field work, and ensure that more people can enjoy fully this experience.”

    Floreana Miesen

    Links

    A multi-pronged FGSE approach of welfare and security

    The FGSE is committed to protecting its students and employees and to improving study and research conditions from all points of view, through various bodies (Health and Safety Committee, Equality Commission, Ethics Commission, internal support for employees), and through more informal steps such as the production of this Handbook.

    This Handbook of Good Practices for Fieldwork in the making is primarily designed as a list of recommendations, and does not have a binding scope like the two Décanat Directives for fieldwork (Directive à l’intention des membres de la FGSE sur la sécurité et les mesures de protection pour le travail de terrain) and off-campus activities (Directive FGSE pour les travaux de recherche impliquant des déplacements à l’étranger).

    The Fieldwork Directive requires each person involved in fieldwork to carry out an adequate risk assessment beforehand, in an autonomous and personal way. It is more focused – although not only – on physical safety in field camps, while the Handbook of Good Practice focuses on the emotional safety and personal integrity of people participating in camps or excursions, so as to make them more accessible. 

    The future Handbook also develops, deepens and thus very usefully complements the concepts that appear briefly in the second directive, devoted to the elements to be taken into account in general when planning off-campus activities.

  • Fossil stories: testimony to a field in transition

    Fossil stories: testimony to a field in transition

    This series of conversations brings you the thoughts of our research community on field practice and how it is evolving. See also :

    Allison Daley, Institute of Earth Sciences

    As a paleontologist, prof. Allison Daley is passionate about the major events in the history of life and the early evolution of animal species. Her approach is to focus on specimens of exceptional preservation quality, enabling her to unravel the mysteries of animals long since extinct.

    Working in the laboratory at ISTE, but also on fossil sites in Morocco, she tells us about the changes taking place in her field and her actions to promote more inclusive teamwork.

    What’s field work like in your field?

    In my field of paleontology, there are two main types of fieldwork. 

    The first is exploration, with the aim of finding new fossil localities. This can be a challenging quest, even if you have good geological maps and try to target outcrops where you are likely to find new fossils. Access is also sometimes complicated, and a helicopter may be required.

    The second involves collecting samples from sites that are known to be rich and interesting. We spend weeks or months sampling specimens, and documenting their stratigraphic and sedimentological context.

    Where is your main fieldwork based?

    My work is based mainly in Morocco. I work a lot on the Early Ordovician Fezouata site, which contains fossils in an exceptional state of preservation. We can find animal soft parts, sometimes even their internal organs. And this site dates back to a period that fascinates me: just after the Cambrian explosion, but before a second great evolutionary radiation that followed during the Ordovician. Analysis of these fossils opens up fascinating perspectives on the early history of the Earth and the origins of biodiversity.

    What local partners do you work with? 

    My team and I go there on average once a year. But most samples are collected by a local professional collector, Ou Said Ben Moula, and his family, with whom we work a lot. He’s the one who found this exceptional outcrop and introduced it to paleontologists. He has no training in geology, but he knows the terrain like the back of his hand and has acquired incredible knowledge. 

    Mr Ben Moula attaches great importance to scientific research and knows how to recognize rare fossils of great value to paleontology. He therefore offers these specimens to museums and research institutes in the field (in Lausanne, Harvard, the Czech Republic…). He also runs a fossil shop, where he sells more standard fossils with less scientific value from all over Morocco.

    In certain regions of Morocco, the economy is based on the sale of fossils. Entire villages are dedicated to the research and preparation of specimens – such as the trilobites sold in “fossil fairs” – and to the sale of rocks containing shelly fossils, often used in construction as decorative building stone.

    In Morocco, ISTE researcher Dr. Pierre Gueriau (middle) and former ISTE PhD students Dr. Lorenzo Lustri (left) and Dr. Francesc Pérez Peris (right) examine Fezouata Shale fossils together with Moroccan fossil collector Lahcen Ben Moula (at back) (Photo credit: A. Daley).

    What happens to fossils from Morocco?  

    Today, the sale of fossils is a highly controversial business. The practice is sometimes perceived as “plundering” a region’s natural heritage. For my part, I understand the aspiration to preserve fossils locally within a Moroccan institution, and I hope that in time this will be possible thanks to the development of infrastructure in Morocco. However, as things stand at present, exporting is still the best way of studying these specimens and preserving them for the long term. 

    Paleontology is undergoing major changes. There is a growing awareness of a colonialist past. It’s true that Western countries have collected and appropriated many specimens, often without any compensation for the regions from which they came. Fortunately, attitudes and mentalities are changing, and there is hope that the situation will improve.

    Interesting initiatives are beginning to emerge. For example, each sample of the Fezouata collection currently housed at the University Claude Bernard Lyon 1 was imported from Morocco and assigned a specimen number belonging to the Marrakech Collections of the Cadi Ayyad University of Morocco, with a view to eventually return them to a future museum in Marrakech. For the moment, Lyon is simply housing these specimens, pending the establishment of a local infrastructure when the samples are returned.

    This initiative has inspired me personally, and I’m currently building collaborations with professors and museums in Rabat and Agadir. I hope that when the right equipment is available locally, we’ll be able to transfer the collections to these Moroccan institutions. In this way, we will contribute to the preservation of the country’s paleontological heritage and promote scientific research at a local level.

    “I think practices are evolving in the right direction, and I’d like to be part of the change.”

    Allison Daley

    What local collaborations exist with researchers?

    The scientific expertise and interest of local people in paleontology has increased. Khadija El Hariri is an active researcher and champion of the Fezouata locality, with whom we have co-authored several articles on the analysis of the preservation of soft parts from the Fezouata site. Vice-President of the International Paleontological Association and a researcher at Cadi-Ayyad University, Khadija El Hariri is extremely committed to the preservation of fossil sites. Together with Khadija and other researchers from Morocco, France, Belgium, Spain and Switzerland, we worked towards having the Fezouata locality designated as one of the First 100 IUGS Geological Heritage Sites.  Led by a collection of Moroccan universities and local organizations, there is also an initiative to create a UNESCO geopark in the Draa Valley region, so that the paleontological and archeological sites can be recognized and protected as a landscape of international importance, and contribute to education and sustainable development.

    Requests for geoparks always come from the country concerned, because if the project goes ahead, it will bring a huge amount of change. For example, the direct sale of fossils will be prohibited, even though many families make a living from this trade. In return, however, the project will enhance the region’s natural heritage and promote tourism. This could create a number of wonderful opportunities, such as the creation of a local museum in Zagora, or awareness-raising activities in schools. It could also strengthen people’s connection to their region.

    Moroccan fossil collector Mohammed Ou Said Ben Moula stands near the Fezouata Shale locality, with the sign announcing it as one of the First 100 IUGS Geological Heritage Sites (Credit photo : A. Daley)

    What do you see as your role as a researcher in a Swiss institution?

    I’ve been invited to sit on the scientific committee for this UNESCO application. I comment on the documents, explaining the scientific importance of the site. But I’m not involved in the political decision, which is up to the region.

    My role as a foreign researcher is also liked to training early career researchers, for example in the scientific methodologies of phylogeny and taxonomy. This is not always easy. Some Moroccan students, although brilliant and motivated, do not qualify for a PhD in Switzerland, or not directly, if they come from a university that’s too technical, for example, or because we can’t get funding. Our university certainly needs to think about how it can welcome and train promising foreign candidates. 

    For my part, I support early career researchers from Morocco in their applications to federal grants, and I hope that soon I will be able to welcome doctoral students and postdocs from Morocco here in Lausanne.

    Do you need special authorization to collect and bring back samples?

    Yes, we have to announce our arrival locally and regionally. This is important for safety and transparency. During our last exploration, it was professors from Agadir who helped us with these formalities and notified the village council.

    The export of collected samples is also regulated by permits. It’s a fairly cumbersome, time-consuming procedure. But it ensures the traceability of the fossils. The Fezouata fossil collection we purchased for UNIL was exported after permits were obtained from the Ministry of Energy, Mines and the Environment of the federal government of Morocco.

    Any advice for young researchers? What do I need to do before going out in the field?

    It’s not always easy to find out what you need to do before going out into the field. Who should I contact? Who provides authorizations? Good information is essential. For this, of course, a local contact is ideal. He or she will be in a better position to know the procedures, which are not always available on the Internet.

    What do you pay attention to when preparing the site? What’s changed today in the way excavations are organized?

    When I started conducting fieldwork as a young researcher, the question of inclusion didn’t arise at all. I sometimes reported situations in which I felt uncomfortable, or even dangerous. I was then confronted with insulting reactions aimed at ridiculing me.

    These are now discussions that I consider essential and that I lead within my group. I don’t want people to find themselves in situations like mine. We attach great importance to mutual respect, so that concerns and difficulties are expressed and taken into account. We have these exchanges before going out into the field, but also in our day-to-day work. We therefore go beyond the FGSE’s recommendations, which include a pre-departure risk assessment [Directive sur la sécurité et les mesures de protection pour le travail de terrain]!

    It’s encouraging to see that these ideas are gaining in visibility, not only at palaeontology conferences, but also in scientific journals in the field. This testifies to a positive evolution in the scientific community. Discussions also address issues specific to women, such as pregnancy, to ensure participation in fieldwork without discrimination.

    Allison Daley in Morocco examining specimens from the Fezouata Shale (Photo credit : P. Gueriau).

    What are your plans for the future?

    An ambitious project that combines paleontological studies with tourism studies… There are some exciting collaborations in the pipeline, notably with a partner involved in the Geopark.

    More information

  • Studying the impact of glacier retreat on biodiversity

    Studying the impact of glacier retreat on biodiversity

    Gianalberto Losapio, Institute of Earth Surface Dynamics (IDYST)




    Glaciers are the guardians of an entire ecosystem, and their disappearance caused by global warming will lead to a dramatic decline in biodiversity.

    In the field, the members of the Biodiversity Change Group are studying and documenting the impact of glacier retreat on biodiversity and ecosystem. Meet the group.


    “It may seem counter-intuitive, but glaciers and their surroundings provide very favourable conditions for biodiversity,” explains Gianalberto Losapio, PI at the Institute of Earth Surface Dynamics from the Faculty of Geosciences and the Environment (FGSE). “With the disappearance of glaciers, we are losing plant species, some of which may have strong medicinal potential, but also the fauna such as pollinators and predators associated with them”.

    With his Biodiversity Change research group, Gianalberto Losapio is spending part of the summer in the field at Ferpècle in Valais, documenting and studying the impact of glacier retreat on biodiversity and ecosystem functions. For several weeks, Bachelor and Master students, doctoral candidates and scientists from various countries are carrying out insect and plant surveys, analyzing soil and gas emissions, and parametrizing models to predict the distribution of species and conserve biodiversity.

    “Overall, we know that melting glaciers initially lead to an increase in biodiversity, with the arrival of pioneer plants and the colonization of insects. But over time, only few competitive species gain the upper hand such as larches and rhododendrons which ultimately dominate the scene”, explains Losapio. “This mechanism is already clearly visible to the nake eye. One of the missions of our group is to study ways of preserving this biodiversity”.


    This is the case of Luca Eiholzer, who is doing a master’s degree in environmental sciences at the FGSE. Equipped with a square meter and a GPS, he lists the presence/absence of targeted species – i.e. bioindicator species such as trees, moss, etc.– in around a hundred randomly distributed points in the proglacial margin. This data is then used to draw up an assessment of the current situation and projections for the distribution of species, with the help of machine-learning algorithms. “We hope that this information will be useful for the authorities, helping them, for example, to define areas to be protected. At the same time, being out in the field allows me to come face to face with the difficulties of collecting data. It’s very instructive.

    ”Eléa Pierre, a Master student specializing in geosciences, ecology and the environment, is interested in the influence that the presence of livestock can have on glacier margins. “I’m carrying out plant surveys around the Zinal, Arolla and Ferpècle glaciers,” she explains. “The idea is to compare changes in biodiversity depending on whether or not there is grazing around the glacier.
    There is a lot of uncertainty around the effects of livestock in these novel ecosystems.

    But according to our knowledge, large herbivores shape their environment, and not the other way round, through their diet, their dropping, trampling and their general behavior. These data could therefore be used to develop different conservation scenarios for sustainable management as these pastures are currently used by local population”.”


    Preparing for professional life

    Data collection generally lasts all day and is carried out by around fifteen people. The members of the group then meet up in a refuge, where they have their meals and spend the night. “Fieldwork is a great experience because, even though everyone is working on a specific project, we can talk to other researchers, help each other and work together,” says Eléa Pierre. Gianalberto Losapio adds: “We want the projects to be carried out independently, from start to finish. The idea is to prepare students for professional life.”

    Art meets science

    The work and research carried out at Ferpècle also include an artistic component. Gianalberto Losapio is collaborating with visual artist and artistic researcher Maëlle Cornut, who is following the group in the field. Funded by Pro Helvetia and the Swiss Polar Institute, the art-science project, which will run for almost two years, focuses on the consequences of the extinction of glaciers on ecosystems, but also addresses broader concepts such as ecofeminism, ecology decolonization and climate justice. It will include videos superimposing micro images of plants and insects and landscape images to show the interconnections between the various scales. “So far, we’ve done a lot of research and shared our practices and ideas. I’ve now started the production phase, installed several cameras traps, and the concrete part of the project is about to begin”, she explains.

    Gianalberto Losapio, Luca Luca Eiholzer and Maëlle Cornut
  • Jorat Natural Park : first steps towards long-term monitoring

    Jorat Natural Park : first steps towards long-term monitoring

    A new peri-urban park was born in the Jorat woods in 2021, becoming the second of its kind in Switzerland.

    Pascal Vittoz (IDYST) is involved in the initial monitoring of this forest, which is entering a new phase following the complete cessation of logging. How will this forest landscape, a favorite walking spot for Lausanne residents, evolve over the next 50 years? The first milestones have been set, and now we’ll have to let the forest give us the answers, at its own pace.

    Armed with a map and a compass, Pascal Vittoz ventured through the thicket in search of the plot he was to survey today. A traverse through the brush reveals an area dominated by spruces. These conifers, planted in the 19th or early 20th century because of their rapid growth, are still predominant today. Without human intervention for economic reasons, this area would be covered with fir and beech today.

    How will the forest, its wildlife and its inhabitants evolve in the future? That’s what this study is all about. Pascal Vittoz is in charge of monitoring the flora, in particular the undergrowth, in order to study the consequences of the creation of the forest reserve on floristic diversity. These surveys will be carried out every 10 years, in collaboration with a commissioned botanist, Loïc Liberati, former student at FGSE (Faculty of Geosciences and Environment) and Patrice Descombes, former student at FBM (Faculty of Biology and Medicine), and current curator at the Lausanne Botanical Garden. They share the 132 monitoring points randomly distributed throughout the forest plots, according to a plan drawn up by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), with the aim of observing the future of the forest.

    The Jorat Natural Park is divided into parcels to facilitate and organize flora monitoring. In the north, the park’s “core zone” is no longer managed by foresters. (Photo: A. Dreiss).

    The new Jorat Natural Park aims to encourage the presence of dead wood. With it, certain birds that burrow into old trunks, beetles whose larvae feed on wood and fungi that decompose dead trees will flourish. One part of the forest – the central zone of the park – will remain untouched for the next 50 years: no cutting, no logging, no off-trail passage. It will simply be left to its natural evolution, with the exception of a few necessary cuts to ensure trail safety. In the transition zone further south, towards the Chalet à Gobet, logging will continue as before, but certain measures will be put in place to promote biodiversity and welcome the public.

    In each plot, the botanists examine two concentric surfaces around the point selected at random by WSL. They describe the structure of the forest and list the flora in the herbaceous, shrub (less than 3 meters high) and arborescent (more than 3 meters high) strata. This gives us an idea of regeneration: if a tree type is present in all strata, it has a good chance of remaining in the future forest.

    The botanists draw up a complete inventory of the flora in two concentric zones, starting from a central point marked on the photo by a blue stake. The first disc, measuring 10 m², corresponds to the standard used for biodiversity monitoring in Switzerland. The second, measuring 200 m², gives a more complete picture of the undergrowth flora, providing a better description of forest structure, such as tree size and proportion of dead wood.

    Pascal Vittoz measures the tree stratum using a convex grid mirror.

    A beetle trap suspended in the middle of the plot bears witness to the various monitoring activities carried out by other groups of scientists. To explore the future of the forest, regular surveys are carried out to study its uses (pedestrians, bicycles, horses) and fauna (beetles, batrachians, deer…).

    After logging ceases, we can expect the trees to age, leading to a denser, darker forest, with less light reaching the ground and therefore fewer plant species in the undergrowth. However, the vagaries of storms and climate change make predictions difficult. Spruces, for example, could suffer from the heat and be partly decimated by attacks from the bark beetle. In a conventional forest, foresters cut down affected trees to contain their proliferation. But what will happen when there are no longer any health checks on the trees? Will the bark beetle spread further? Will their presence favor species other than spruce?

    « This reserve is set up for 50 years, which is more than half a human lifetime, or about ten times a standard research project. » Pascal Vittoz

    So we’ll have to wait to see the benefits of this park materialize. Typical research projects are planned to last 3 to 4 years. In this case, that’s not long enough to study forest flora, which evolves very slowly. This study, which spans the entire lifespan of a tree, will not deliver its results for several decades.

    What do botanists find in the Jorat woods?
    Wood horsetail
    (photo : P. Vittoz)

    The forest is dominated by spruce and beech, with undergrowth often lacking in plant diversity. However, some wetter areas, such as ash groves, offer surprises and less common species. Horsetail, a common species in the Alps but much more widespread on the Plateau. Horsetails are among the oldest plant species, having appeared nearly 400 million years ago. Some species were important trees in the Carboniferous period, while today’s largest representatives grow to around 1 m.

    More informations

  • Uncovering the secrets underground: how micro-scale processes in soils have global impact

    Uncovering the secrets underground: how micro-scale processes in soils have global impact

    Marco Keiluweit is a specialist expert in soil biogeochemistry who joined the Institute of Earth Surface Dynamics in July 2022. He is particularly interested in the role of soils in climate change and the global carbon cycle. His current research focuses on fundamental processes that regulate soil organic matter dynamics, which determine soil carbon sequestration and soil health. Here, he and his first assistant Emily Lacroix talk about the team’s ambitious agenda. It encompasses both the grand scale of natural environments and the microscopic intricacies at play within them. By connecting these dots, their work will pave the way for advancing our understanding of the complex interplay between soils, climate change, and sustainable agriculture.

    Exploring a complex universe

    Marco Keiluweit: Conducting research in soils is a challenge: they are highly complex and dynamic systems. Plants, microbes, minerals, and organic matter interact and are in a constant state of flux. My aim is to gain a better understanding of the dynamics governing soils. Isolating and describing the physical, biological, and chemical processes involved is a long-term quest.

    Soils are much more than just a pile of dirt; they are teeming with life, with plants, microbes, and minerals interacting in a complex choreography. The physical, biological and chemical processes animating this dance are so intimately interwoven that it becomes difficult to isolate and study them individually.

    The carbon cycle in soils is the key focus of  our research. We are seeking to better understand the mechanisms that store carbon in soil or release carbon from soil. This capacity determines whether soils will accelerate or help mitigate climate change in the future. In fact, soils store around three times more carbon than the atmosphere and biosphere combined. Understanding how soil carbon cycling is affected by climate change is therefore of the utmost importance. 

    Beyond the environmental aspect, the study of soils is also of crucial economic interest. Agricultural fertility and productivity are closely linked to soil carbon cycling. Understanding how this precious element influences the quality of arable land paves the way for more sustainable and efficient farming practices.

    From macro to microscope approaches

    Marco Keiluweit: Delving into the intricate mechanisms of the carbon cycle and deciphering the impact of environmental perturbations such as climate change on these processes requires a multi-level approach. At a macroscopic level, our ultimate goal should be to tailor land management strategies to the unique characteristics of each soil type, achieving the delicate balance of optimizing plant productivity while curbing CO2 emissions.

    By unravelling the intricate relationship between soil management and carbon storage in the soil, scientists hope to unlock the key to maximizing yield while minimizing the carbon footprint of agriculture.

    We are also studying natural ecosystems, for example in the Alps. In alpine soils, 90% of carbon is stored in soils. We are interested in assessing how this vast soil carbon pool responds to changing snow cover. We are currently monitoring how the soil carbon cycle in these systems responds to changing snow melt dynamics in alpine regions.

    Soil microelectrodes that continuously measure the chemical parameters influencing carbon cycling in soils, for example nutrient levels, oxygen content, moisture, etc. Placing several of these sensors in a field allows scientists to assess the spatial, seasonal and temporal variations in soil carbon dynamics in the field.

    Marco Keiluweit: On a smaller scale, our research focuses on the rhizosphere. This is the soil zone where plant roots meet the soil. Roots release carbon compounds into the soil (sugars, organic acids), which microbes absorb, fix in the form of organic carbon, then metabolize and release in the form of CO2. A detailed understanding of these plant-microbe-soil interactions and their variations will enable us to determine under which conditions the soil will tend to store or release carbon.

    A prototype for studying the root system under controlled conditions. The plant is grown in vitro in a medium contained between a glass plate and a molded polymer. It is also possible to test different factors such as nutrient and humidity levels or the presence of micro-organisms on gas transport and consumption.

    Emily Lacroix: My particular interest is in anoxic microsites: pockets in which there is no oxygen. This is particularly true in the vicinity of roots. These pockets have an influence on the global carbon cycle, as microorganisms there convert organic carbon into CO2 less rapidly. My main questions are: where and how do such microsites form in the rhizosphere? Is their frequency linked to soil moisture or texture? Can we measure their influence on the soil’s capacity to fix or release CO2?

    To observe the formation of anoxic pockets (microsites) in situ, Emily Lacroix inserted soil into a reactor. The same soil is mixed with quartz crystals (not very reactive) of different sizes to simulate variations in texture without changing the nature of the soil (see different colours of samples in the image on the left).
    A “false root” – corresponding to a microdialysis probe (photo right) – releases carbon into the soil, just like a real plant root. Its advantage is that it allows precise control of the amount and type of carbon released into the soil.
    The soil’s moisture content can also be modified to identify its potential influence on the formation of anoxic pockets.

    At the end of the experiment, Emily Lacroix measures the oxygen level and its distribution in the sample: a chemical foil reacts to the presence of indicator oxygen (pink square on the left image). This paper is then exposed to a camera equipped with a UV lamp (central image). On the screen, oxygen-rich areas appear orange-red and anoxic areas yellow-green (right image). In this way, it is possible to quickly identify the distribution and number of anoxic zones in the vicinity of a root.

    Marco Keiluweit: Finally, on a microscopic scale, we analyse soil samples using a cutting-edge, high-resolution infrared microscope. Its high level of resolution enables us to describe the interactions of organic matter, minerals or microbes in our samples.

    Characterizing the associations of microbes and minerals in soil samples is one of the feats made possible by the infrared microscope. The resolution of this microscope makes it possible to distinguish different types of soil organic matter (dead or alive) and minerals in soil samples.
    This is the only infrared microscopes of this kind in Switzerland and has a rapidly growing user base FGSE as well as at other  institutions in the fields of geosciences, microbiology and engineering.

    The Road Ahead: Linking fine scale mechanisms to macroscopic observations

    Marco Keiluweit: Our aim is to better predict how soils respond to climate change going forward. And we can only improve our predictions of this response by linking macroscopic observations of change to microscopic mechanisms. We have seen a rapid advance in our understanding of soil carbon dynamics in recent years, which makes me hopeful that we will be better equipped to address the mounting pressures on our soils arising from climate change and intensification of land use in the future

    Emily Lacroix: I hope that my first experiments under controlled conditions will be conclusive, so that I can measure the formation of anoxic pockets (microsites) close to real roots under real conditions. With successful results, I aim to conduct measurements that will enhance our understanding of how these crucial processes influence soil carbon dynamics. 

    Pour en savoir plus

  • Investigation in Madagascar – ethnographic fieldwork in a rural landscape

    Investigation in Madagascar – ethnographic fieldwork in a rural landscape

    This series of conversations brings you the thoughts of our research community on field practice and how it is evolving. See also :

    Christian Kull, Institute of Geography and Durability

    Christian Kull is interested in environmental management in rural landscapes. He has worked in Tanzania, Kenya, India, Vietnam… But it was in Madagascar that he completed his master’s and doctorate. He fell in love with the landscapes of the country’s high plateaus, a mix of forests, terraces and small farms. He tells us how he conducts his ethnographic fieldwork.

    Christian Kull is a geographer. His work aims to shed light on the global environmental issues of our time. Environmental management is a central issue affecting human well-being, economic prosperity and sustainability. Rooted in the scientific disciplines of Political Ecology, Development Studies and Environmental Humanities, Christian Kull explores the historical, ideological and political-economic genesis of environmental problems and the conflicts that accompany them. To understand the dynamics of governance and foreign intervention, he has worked in deprived regions of the world.

    Christian Kull was president of the CER-GSE when it was launched in 2020, and helped to set it up. In this interview, he talks about his long-term work on wildfires and invasive plants.

    What partners do you work with?

    I have a particular interest in local stakeholders. I try to understand how people manage the environment around them, why they plant this or that, cut down trees, burn vegetation… And how these practices interact with national and international policy.

    So I work mainly with peasants, but also with people in the rural world – those with administrative positions, the pastor (churches play an important role here), the local school teacher – and on a more global level, with government and NGO officials, people in bilateral aid and at the university.

    Malagasy farmers explaining land use (Photo: Ch. Kull, 2006).

    How did you first come into contact with the people you want to interview?

    Now, I almost always undertake a project in partnership with the local university, in particular with their school of agronomy, forestry and environment, but also with the geography department. For my Master’s, it was totally different: I bought a plane ticket without knowing whether the professor to whom I had sent a handwritten letter had received it. As soon as I arrived, I knocked on the doors of people at the University of Antananarivo whom I knew only through their articles.

    They introduced me to a student, Arsène Rabarison, whom I then hired as a field assistant, as I didn’t speak Malagasy yet. Arsène also helped me in my learning: discovering rural life, knowing how to behave, learning about networks and how to find accommodation, etc.

    The peasants are welcoming, and in the hamlets you’ll always find someone to offer food and a place to sleep. The next day, they sometimes send a child to show you the way for a few hours.

    “In 1994, I set off with the 1969 Atlas of Madagascar. Some of the plates caught my interest: very precise field maps, 1 km by 1 km, where land use was mapped. My idea for the Master’s degree was to go and see 25 years later what had changed, and to explain these changes by talking to the people on the spot. I arrived in a village I’d chosen without knowing anyone there. But I could show them this map. Some of the elders even remembered the ‘French professor’ who had made it!”

    Do you need permission to discuss your research questions?

    I deal mainly at the local level, with the local town hall. But I also have a letter from the university. For local officials, it’s already a passport if someone in the capital has validated the project.

    When I worked at Monash University in Melbourne, Australia, I had to follow a more bureaucratic ethical procedure, guided by the challenges of medical research, and aimed at avoiding past abuses towards Aborigines – who suffered from exploitative research. In Madagascar, I always managed to argue for oral consent adapted to local traditions (including formulas for thanking God…). I think the farmers appreciated this effort! For them, signing a piece of paper is rather worrying, and they don’t always read well, so oral consent is preferred.

    The ethical form advocated by my thesis university in the USA and by Australian universities was based on the premise that we alone are in a position of domination and power in relation to the locals in these exchanges. Although I have also observed that the figure of the researcher sometimes still commands too much “postcolonial” respect, I am critical of this perspective. I have chosen an oral consent procedure for pragmatic reasons, but also out of conviction. I consider that the people I interview also have a form of power, so I don’t need their signature to formalize our interaction. And I observe it too: if they don’t want to answer, they skirt around the questions with ease, they lie… I trust them! The key point before an interview is to say what I’m doing, that I’m not going to use their name and that they can choose not to answer.

    (Photo : Ch. Kull, 1998)

    How do you deal with sensitive issues that can get people into trouble?

    I’ve worked on fires, which are often illegal. But I never ask directly who started a fire. Instead, I’d say: “Did you see the day before yesterday, there was a fire up there. Why?”. And I’m never told, “I lit the fire for that reason”; but, for example, “I suspect that whoever lit it did so for that reason”.

    In my research, I move forward by piecing together observations, by triangulation, building up an argument little by little as if I were conducting an investigation. The Malagasy way of speaking is also rather indirect, so you have to know how to decode!

    How do you protect data on illegal practices, such as fire? Do you need to ensure source anonymity?

    The issues I’m working on with my partners and team are not highly sensitive, and again, the evidence is indirect since no one says “I started that fire” or “I cleared that forest illegally”.

    However, from the outset, the information gathered is separated from the real name of the source. And no file contains both elements, thus preventing cross-checking. If necessary, a correspondence file exists, but separate and password-protected (the name of the file shouldn’t be obvious about the nature of its contents either!).

    During my PhD, in my notebook, there were no real names. “Goatee” referred to someone with a small beard. I named a peasant “Ruedi”, who reminded me of my uncle of the same name…

    “The context of the interview is important: are we going to people’s homes? Is it relevant? Socially possible? Do we have their trust to do so? What do we have to give in return? Farm families often offer food. During my thesis, I decided to take a photo of the family – back in the days of 35mm film camera, when you had to go up to the city to develop the photos. It wasn’t a means of exchange, but a way of thanking them… That said, after 20 families, word got around, and when I arrived for an appointment, they’d put on their Sunday clothes. It made them really happy.” (Above: examples of family photographs to thank participants. Photo: Ch. Kull, 1998)

    What advice do you have for young researchers before they head out into the field?

    I brainstorm with them on interview guides, but the field is really a learning experience. I trust them. You have to dare to try things out, see what works and adjust if necessary.

    At Bachelor’s level, students are introduced to qualitative research and learn how to construct a survey. So they have a good grounding, and good manuals too. But it’s all theory … until you’re facing someone you want to interview!

    How do you get people to agree to talk about their practices? It’s a social process, where a smile and the way you present yourself are just as important as your knowledge of cultural codes (what’s acceptable, what’s not). Sometimes it’s explaining what you’re doing that’s decisive, sometimes it’s convincing the mayor beforehand. But fortunately, in Madagascar as elsewhere, people like to talk about their lives, as long as someone is interested.

    In the Master’s program, we also try to expose students to an “exotic” context. It has to be justified in terms of budget and climate impact, but these are essential learning moments.

    Are there any mistakes to be avoided when designing an interview?

    A subject close to my heart is that of invasive species. At the beginning, some students ask questions that already contain the answer: “What do you think of these invasive species?” If we ask the question like that, the foresters or farmers will try to please us, and say that these species “invade” them… If we ask them, “What do you think of eucalyptus, their strong and weak points?”, we’ll get other answers. Only then can we go further: “Have you heard that they are invasive? What does that mean to you?” It’s not the same conversation.

    “Here I am with farmer and shop-owner Augustin “Radatatoa”, in 2018, in Laimavo, Madagascar. He’s carrying photos taken in 1994 during my master’s work, which I mailed to him.” (Photo: Ch. Kull)

    How has your relationship with local people developed over time?

    For my PhD, I decided to spend four and a half months immersed in the culture and taking intensive Malagasy language courses. Every afternoon, I got on my bike and went to practice basic exchanges with farmers (“Do you grow rice?”). Then I lived in a village for 10 months. Staying in the field for so long allows you to learn a lot about the context in which specific issues are situated. For me, this is invaluable, and it’s the only time in a career when you have the freedom to do this. Little by little, you come to understand the networks, the stories of friendship, family, clan, religion, all those things that are so opaque at first. That’s what our students don’t always have the time to do now.

    The ethnographic approach takes time. It’s quite different from the more formalized research interactions that are now being taught more and more.

    “I work the old-fashioned way, notebook in hand. At the end of the day, I add notes, reconstruct, sort. I note down my observations, my conversations, but also all my encounters. Otherwise, two years later, I get everything mixed up, and it’s essential to remember people.”

    To go further

    Christian Kull, Institute of Geography and Durability

    Christian Kull is an expert in research on wildfires, a phenomenon that has a major impact on carbon dynamics, biodiversity and ecosystem services. As part of a SNIS project (Swiss Network for International Studies), he is currently exploring the most balanced fire management strategies to meet the needs of local communities and the challenges of climate change. With partners from Swansea University (UK), Antananarivo University (Madagascar), Eduardo Mondlane University (Mozambique), the South African National Parks and the UN Food and Agriculture Organization Madagascar, he is targeting biodiversity hotspots in Madagascar and southern Africa.

    He has also contributed to our understanding of invasive species and plants, deforestation and reforestation, protected areas and agricultural conversion.

    Discover Christian Kull’s profile, blog and scientific publications.

  • Sampling expedition off the coasts of Vancouver: first step to a better understanding of the cycle of chromium in the ocean

    Sampling expedition off the coasts of Vancouver: first step to a better understanding of the cycle of chromium in the ocean

    Isabelle Baconnais, Institute of Earth Sciences

    Isabelle Baconnais, a member of the BOAT (Laboratory for Biological Oceanography Across Time, Institute of Earth Sciences, ISTE)research group, led a maritime expedition off the coasts of Vancouver in October 2022.

    She collected seawater samples and suspended marine particles to measure their chromium content. Her objective is to ultimately determine whether this element could become a tracer of the activity of the marine biological pumps, which have an important role in the ocean carbon cycle.

    These pumps help moving the atmospheric CO2 that dissolved in the surface waters towards the deep waters, thus helping to regulate the planet’s climate by trapping it into the Oceans for hundreds of years. A more precise quantification of the capacity of the biological pumps to transfer the CO2 towards the deep waters would allow to better predict their potential role in regulating the climate change.

    The oceans cover more than 70% of the Earth’s surface. They have a significant influence on the climate, particularly through the absorption of atmospheric carbon dioxide (CO2), one of the main greenhouse gases. Photosynthetic microorganisms (phytoplankton) in surface waters use the dissolved CO2 to generate organic carbon, similarly to terrestrial plants. Phytoplankton are then ingested by other organisms, and some of this organic carbon “sinks” to the deeper waters as e.g. feces or dead bodies. The biological processes participating in the ocean carbon sequestration from the atmosphere are referred to as the biological carbon pump (BCP). This pump is essential for the climate balance. Since the beginning of the industrial era, it has already absorbed about a third of CO2 emissions related to e.g. the combustion of fossil fuels.

    Biological carbon pump (source: ocean-climate.org)

    Several scientific teams have been trying to assess to what extent the activity of this BCP is, or could be, impacted by climate change and viceversa. Modelling of the carbon export is hampered by many uncertainties (e.g. change in the water masses circulation or variation in the nutrient inputs to the ocean). The direct use of carbon as a tracer of the BCP is limited by its ubiquitous presence in high concentrations in the oceans and by its use in various physical and biological processes (photosynthesis, respiration, dissolution etc…) that do not allow clear distinction and quantification of the processes specifically tied to the BCP.

    Chromium has recently become of interest for its potential correlation with the transport of carbon to the deep waters of the modern oceans. However, no direct measurements of chromium in marine particles are currently available to confirm this suggestion (see note). Isabelle Baconnais is conducting research to fill this gap.

    Below, the researcher describes her expedition off the coasts of Vancouver to collect samples of seawater and suspended marine particles (pictures from Maxime Curchod).

    Autumn in Vancouver

    In October 2022, we boarded the Canadian Coast Guard’s hovercrafts SIYAY and MOYTEL for six exciting days in the Strait of Georgia and Saanich Inlet in Canada’s Eastern Pacific. The Strait of Georgia is a dynamic waterway that separates the city of Vancouver from the picturesque Vancouver Island. Saanich Inlet is a partially anoxic fjord, with little to no dissolved oxygen in deep waters, within Vancouver Island.

    The sampling site offered an excellent opportunity to collaborate with scientists from the University of British Columbia (UBC). The laboratory of Professor Roger François supplied the pumps used for the collection of the suspended marine particles. His team (i.e. Maureen Soon) also facilitated contact with the coast guards for the organization of the sampling trips. The equipment and experience provided on site greatly contributed to the success of this sampling expedition.

    The team of Lausanne and Canadian scientists on the deck of the SIYAY.
    From left to right: Isabelle Baconnais, Ed ward Mason (UBC student, back), Roger François (UBC professor, front), Maxime Curchod (FGSEstudent), Lisa Kester, Nicole McHugh and Morgan Griffith (UBC students). Two members of the incredible Coast Guard team in the background.

    Every morning, we arrive at the coast guard’s base to find the massive hovercraft waiting for us on the asphalt. Once the coast guards and scientists finish loading their respective equipment, the hovercraft inflates, and we are in our way in the blink of an eye. Its speed is such that it is forbidden to leave the cabin during transit, lest we be thrown overboard. In return, we quickly arrive on site and begin sampling in the crisp autumn morning of the Canadian West coast. We were particularly lucky regarding the weather since it was unusually sunny and warm for most of the expedition.

    The Vancouver Coast Guard hovercraft: these boats can get into the water very quickly and sail at high speed. They are equipped with the winches and cables needed to immerse the heavy pumps used to sample the marine particles. The sampling trips were carried out over three times two days.

    Using the Canadian coast guard’s hovercraft implies that rescue missions take precedence on the sampling. In case of an emergency call, all sampling device then needs to be quickly brought back onboard and secured as fast as possible. Fortunately, this only occurred once during the entire expedition, and in this instance, we were quickly able to get back to sampling.

    Sampling at sea

    Daily, we proceed to sampling under the curious gaze of the jumping salmons, the killer whales or the sea lions: we immerse the ~30 kg–large volume pumps at specific depths, through which hundreds of liters of water pass and allow the recovery of the suspended marine particles on filters. We also collect seawater in 20L bottles specifically designed for sampling for elements susceptible to contamination, called Go-Flo bottles. We distribute the water into bottles that will be used for different analyses (salinity and oxygen of the water, cadmium concentration, dissolved chromium concentration and isotopic analysis, particulate organic carbon concentration).

    Morgan, Rowena Diggle (student at UBC) and Isabelle collecting seawater samples from the Go-Flo bottles. The flacons must be clearly identified per depth and station, and properly manipulated according to the measures they will be used for. The Go-Flo bottles are hung on a non-metallic line and immersed in water, each at a pre-defined depth. A system of rotary balls allows them to close when given the signal, in order to trap the seawater they contain. These bottles are made without metal elements so as not to contaminate the samples. In general, all equipment coming into contact with the sampled water (winches, containers etc…) must be treated to avoid metal contamination of the samples.

    The unusually warm weather of the early autumn 2022 resulted in elevated biological activity.  The filters recovered from surface waters testified to this, with their beige to greenish color  and their sushi smell. The most notable sampling took place in the deep waters of Saanich Inlet, where the lack of oxygen could be surmised from the strong rotten egg smell emitted by the waters sampled. This smell is characteristic of the bacterial production of hydrogen sulphide H2S in anoxic environments.

    Two killer whales, native to the region, join us on our sampling, taking advantage of the abundance of food offered by a mild weather, late in the season.
    The difference in colour reflects the varying composition of the suspended particles at Saanich Inlet: from the surface waters, rich in biological products (left) to the deep anoxic waters below 140 m (right). The filters sampled at 90 m and 125 m are enriched in iron and manganese oxides, giving them their reddish color.

    Why is chromium of interest? 

    Chromium is a trace element found in seawater in concentrations of the order of 0. 0000001 g per litre of seawater. Its concentration and isotopic ratios vary according to its distribution between chromium 6 (Cr(VI)) and chromium 3 (Cr(III)). Cr(VI) preferentially remains dissolved in seawater while Cr(III), isotopically lighter and formed from the natural reduction of Cr(VI), tends to adsorb onto marine particles.

    The measurement of dissolved chromium concentrations and isotopic ratios has shown that chromium is lost in surface waters and remineralizes deeper in the oceans, which appear to be related to surface biological activity and the marine particle cycling. Direct measurements of chromium in marine particles are currently lacking to confirm these observations. 

    This study, and more broadly the SCriPT project (see ref.  at the bottom of the article), aims to establish a method for measuring chromium concentration and isotopic ratios in marine particles in order to potentially use chromium as a tracer of the marine carbon flux to the deep waters, in other words, the oceanic BCP activity.

    First objective achieved

    Despite the several technical difficulties encountered during this trip (especially due to the fussy large volume pumps), the sampling was overall successful in both the quantity and the quality of the water and particles collected. It is now time to focus on measuring chromium and its isotopic ratios. Protocols do exist for measuring chromium dissolved in the waters, but they are yet to be established for measuring the chromium attached to the suspended particles.  These samples represent the first steps towards a deeper understanding of the cycle of chromium in the oceans.

    Chromium, which is not known to be used in biological processes, could become an excellent tracer of the particles that drive carbon from surface to deep waters, and therefore an indicator of the changes in the BCP brought upon by climate change.

    For more information

    This study is part of the European research project Horizon2020 SCrIPT Stable Chromium Isotopes as a Productivity Tracer (project obtained by Professor Samuel Jaccard of ISTE)

  • High pressure experiments: laboratory tour with Prof. Lukas Baumgartner

    High pressure experiments: laboratory tour with Prof. Lukas Baumgartner

    Lukas Baumgartner shares with us a typical day. Alongside him, we wander from one laboratory to another. On today’s schedule: measurement launches punctuated by intense team discussions.

    In front of three screens, concentrated on the complex settings of the Electron probe microanalyzer, Lukas Baumgartner from ISTE is about to make tonalite (granitoid) stones speak, extracted from an Italian site that he has been studying since his PhD. 

    Moving bodies that tell the story of Earth

    Lukas Baumgartner wants to know everything about the chemical composition of these tonalites and the surrounding rocks – metamorphic sediments. But to understand his approach, we must first go back in time. A long time back.

    The Earth was formed after the Big Bang, by accretion, gradually forming a core, which attracts the heaviest elements, a viscous mantle and a crust that hardened by cooling. In Lausanne, we walk on a crust of about 30 km thick that “floats” on the mantle. The flow of rocks between the crust and the mantle brings them to collide, to move apart, to plunge… These geological movements have consequences on the composition of the rocks, but also more global consequences. The formation of the Alps, for example, is one of them. The variations of CO2 in the atmosphere also result from these phenomena, which is not without importance in these times of global warming!

    “I study a part of these mechanisms, a very small part!” 

    Lukas Baumgertner
    Deep in the earth, the rocks are subject to impressive pressures. The Gotthard tunnel, under 3 km of rock, is already under a pressure of 1000 bars. The rocks are solid, but they move slowly, inexorably. “In the long term, without supervision, a tunnel is bound to be crushed.” (© Tringo | Dreamstime.com)

    Big questions in a human-sized laboratory

    To understand these flows of plutonic rocks under our feet, their thermal consequences and the life span of “thermal anomalies” linked to magma, different methods are available to geologists. Drilling is one of them, but the temperatures and pressures are so high at depth that one hardly goes beyond 10 km. The other solution is what Lukas Baumgartner is using here: studying the rocks accessible at the surface and tracing their history through their chemical composition. At the same time, he exposes minerals to high pressures and temperatures, and compares the consequences of these experiments with what we observe in nature. Finally, thanks to physical laws – such as the diffusion of heat in rocks, or the diffusion of elements in minerals such as garnet – we can estimate the chronology of geological phenomena, such as short igneous and metamorphic events.

    In practice, the Electron probe microanalyzer sends electrons onto the thin section sample (picture below) and measures the emitted X-rays, characteristic for each element. This results in quantitative chemical analyses with high spatial resolution. For these delicate machines, qualified technical support is crucial. In this case, researcher Martin Robyr is always there in case of problems. 

    The collected rocks must go through the sawing and then to the Thin section lab before being analysed with a microprobe. First, the raw or rough rock is cut [top left]. A small saw with a diamond wire allows then the most precise cuts [right]. Finally, the rocks cut in thin layers of 30 micrometers (µm) thick. (© N. Bourquin)

    Here we are, the measurements are launched on the microprobe. While waiting for the results, Lukas moves on to a parallel project. This time, it is about foraminifera and climate history.

    Climate change: an issue as old as the Earth

    While scientists speculate about the intensity of future climate change, the temperatures that the Earth has experienced in the past are also being debated. Our window of observation of the Earth’s temperatures, our archives, are notably the foraminifera. The isotopic composition of these fossilized microscopic marine animals is indeed used to trace the temperature that prevailed during their lifetime. But today, some researchers question whether these isotopic measurements could also be altered by the conditions undergone after the death of foraminifera. In a joint project with Prof. Anders Meibom and his colleagues, Lukas Baumgartner has decided to analyse the reliability of isotopic results. This could change our entire view of the Earth’s history.

    Obviously, once again, to perform a life-size experiment and observe the transformations of foraminifera over several million years is not feasible. As an alternative, why not subject the foraminifera to very high temperatures and pressures, but for a shorter time? An experiment that takes place in a researcher’s time, not that of fossil foraminifera. Then, the researchers will examine the effects on their composition; then, extrapolate over several thousand years what they observed in a few hours. This works because the diffusion law – which describes the change in isotopic composition as a function of time – is proportional to temperature and pressure.

    The key to the enigma in the crystal

    Foraminifera are notably made up of an accumulation of calcite crystals on a nanometric scale. To elucidate the age of foraminifera, one can therefore also look into a calcite crystal (photo below) of the same composition. This is what Lukas Baumgartner and his colleagues are discussing over coffee. The team wonders what diffusion measurements to make on the crystal: at what angle? How to cut the crystal? And how accurately? Each of these details counts. And the decision is based on the literature and the technical means available… 

    (© N. Bourquin)

    Beware, hot stoves

    How to handle such high temperatures and pressures? The hydrothermal lab can reach 2000 bars – the pressure undergone by rocks 7 km below the surface – and 800 °C! To resist the highest pressures, tubes – called bombs – of stellite are used, which resist explosion up to temperatures of 850 °C under pressure. One of these tubes, broken, is prominently displayed next to the installation: it reminds the experimenters that manipulations at these levels of pressure and temperature are eminently dangerous and that the name of these tubes is no coincidence! These tubes are supposed to be almost unbreakable, but this one exploded violently when it cooled down too quickly in contact with water…

    (© N. Bourquin)

    In the furnaces, the samples to be studied can also take placed in mini-tubes of gold or platinum: these metals react very little and resist temperatures up to 1560 °C. 

    In this laboratory, it is also possible to study the composition of minerals and the reaction of water heated to very high temperatures, in order to reconstruct the pressure and temperature conditions experienced by metamorphic rocks. The composition of fluids is for example essential to understand the fluid-rock interactions in geothermal systems. The diffusion rate of the elements is also determined here: it allows to evaluate the critical temperatures and pressures (called critical constants), which give an idea of the stability time of the minerals according to the conditions they go through.

    The tour ends here, and if you want to know more, follow the team’s results!

    More informations