I work as tenured Associate Professor of Soil Chemistry at the Earth Surface Science Research Group of the Institute for Biodiversity and Ecosystem Dynamics.
In addition, from 2014 to 2020 I was Director of the Bachelor programme Future Planet Studies.
Of the various soil scientific disciplines, soil chemistry holds my particular interest. I am fascinated by biogeochemistry in general and in particular by understanding the fate of Soil Organic Matter (SOM) in terrestrial ecosystems. How does the chemistry of soils and sediments regulate the transport, transformation and preservation/degradation of SOM? How is this chemistry, and thereby the fate of SOM, altered by natural or human-induced change? What are the implications for the functioning of ecosystems, and how can we use this knowledge to optimize the ecosystem services rendered by the soil?
For my personal background and CV, more information about my research interest, or a list of my publications, please click on the appropriate tab above.
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You can download my complete Curriculum Vitae in pdf format via the link below.
As Associate Professor I am responsible for research and teaching (Bachelor, Master and PhD levels) in Soil Chemistry.
I provided a detailed description of my current research interest on a separate page. Please click here or select the tab 'Research interests' above.
I am also currently Director of the Bachelor program Future Planet Studies
As Assistant Professor I was responsible for research and teaching (Bachelor, Master and PhD levels) in Soil Chemistry.
Research topic: upper forest line transitions in the Ecuadorian Andes
During my Postdoc project, I worked in the multi-disciplinary RUFLE research project of the Earth Surface Processes and Materials research group and the Paleo-Ecology and Landscape Ecology research group of IBED, together with two PhD students.
The overall aim was to study past upper forest line fluctuations in Ecuador and use the information to reconstruct the natural position of the upper forest line in the absence of human impact in the form of clear-cutting and burning. To this end, I developed a new technique to reconstruct past vegetation compositions. I showed that a combination of chain-lengts of n -alkanes and n -alcohols from the epicuticular waxes on the leaves and roots of plants can be used to distinguish plant species from one another, and developed a first database of such patterns in Ecuadorian vegetation. I was also able to prove that the straight-chain lipid patterns are preserved unaltered in peat deposits and in the volcanic ash soils of the Ecuadorian Andes for thousands of years. In close cooperation with the Computational Geo-Ecology group of IBED, I subsequently developed the advanced, new 'Vegetation Reconstruction with the Help of Inverse modeling and Biomarkers'(VERHIB) model to unravel such mixed straight-chain lipid records into the most likely combination of plant species from which they originated. Within the project we combined the results of this so-called biomarker analysis, with fossil pollen analysis. This combination of proxies greatly enhanced our abilities to reconstruct past vegetation dynamics and allowed us to reconstruct past forest compositions and past upper forestline dynamics in the Ecuadorian Andes with previously unattainable accuracy.
Research topic: the mobility of aluminium, iron and organic matter in acidic sandy soils.
During my Ph.D. studies, first I succesfully tested the applicability of the new experimental technique of diffusive gradients in thin films (DGT). Specifically, I investigated its ability to distinguish 'free' dissolved Al and Fe from their dissolved organic complexes. Subsequently, I used a combination of DGT and mathematical modeling (Model V and Model VI) to investigate the influence of changes in pH and metal/organic carbon ratios on the degree and type of complexation of Al and Fe with dissolved organic matter in acidic sandy soil solutions. Finally, I used a combination of the before mentioned techniques to study the role of the interactions of Al, Fe and organic matter on the formation of podzols.
Altogether, my research led to a firm establishment of the DGT technique and further vindication of Model Vand Model VI for the analysis of Al and Fe speciation in acidic soil solutions. Furthermore, my studies gave new insights into the mechanisms that regulate the mobility of Al, Fe and DOM in acidic sandy soils in general and the process of podzolization in particular.
Environmental Chemistry is a study of analytical chemisty that focusses on environmental issues such as soil- and water pollution. Within the framework of my Masters studies I investigated:
In general, my current research interest lies in the study of the carbon cycle in soils from a molecular point of view, and in particular the influence of land management and environmental change on (soil) ecosystems.
The LEX4BIO project: closing the N and P loops in agriculture without polluting soils and crops
LEX4BIO is a large EU Horizon 2020 collaborative project that will identify and quantify nutrient-rich side-streams and evaluates technologies for producing safe, efficient and regionally targeted bio-based fertilizers in the EU. LEX4BIO provides policy recommendations for achieving a higher use efficiency of bio-based fertilizers and socioeconomic improvements for the rural population.
Together with University of Amsterdam colleagues Chris Slootweg and John Parsons I will lead the workpackage that focussses on risk assessment of the application of novel recycling fertilisers. When we use waste streams to produce fertilizers in an attempt to close the P and N loops, what are the risks of introducing contaminants? What contaminants should we worry about? What can we expect to be their fate and bioavailability in soils? And how can prevent them from potentially ending up in the crops grown on those soils?
The project just started and will involve a PostDoc and a PhD researcher at the UvA.
Boosting women’s production, processing and trading of quality foods in Africa’s growing cities can improve food and nutrition security of vulnerable populations. This inter- and trans-disciplinary project examines opportunities and constraints, field-tests innovative food production and processing methods, and designs inclusive business models for women food entrepreneurs.
As co-PI of this NWO-WOTRO funded project I collaborate with UvA colleague Dr. Nicky Pouw of the Governance and Inclusive Development Group of the Faculty of Social and Behavioural Sciences and several partners from The Netherlands, Kenya, Burkina Faso and Germany to lead three PhD students: Tamara Jonkman (Natural Sciences, IBED), Likoko Eunice (Social and Behavioural Sciences, AISSR) and Kini Janvier (Social and Behavioural Sciences, AISSR).
More information and the latest news about the project on: http://knowledge4food.net/research-project/women-food-entrepreneurs-in-kenya-and-burkina-faso/
Water management in low lying Delta Areas in many cases requires control of infiltration or seepage of water. We aim to develop a bio-based geo-engineering technology for in-situ permeability reduction that will be applied to reduce the infiltration loss or the seepage burden due the unwanted flow of water through highly permeable layers in the sub-surface. Naturally occurring processes involving the precipitation of organic matter and aluminum reduce the permeability. We aim to utilize the great potential of these natural processes for engineering purposes. Members of the user group provide access to casestudy sites, provide existing data and enable and facilitate the acquisition of new data. In addition, they will also carry out a field test based on the proposed in-situ technology. Development of applied in-situ technology and fundamental insight to processes are parallel processes in this program.
As co-PI of this NWO-STW funded project I collaborate with Prof. dr. Timo Heimovaara and Dr. Susanne Laumann of TU Delft as well as several partners from The Netherlands and Germany to supervise two PhD students: Olaf Brock (IBED, UvA) and Jiani Zhou (Geo-engineering, TU Delft).
More information about the project on:http://www.stw.nl/en/node/7142
Within the plethora of soil functions, the role of soils in the global carbon cycle continues to fascinate me. Not only because of the obvious link with climate change, but also because of the relation with fertility and therefore food supply. To unravel the carbon cycle in soils we need detailed soil chemical investigations of carbon dynamics under climate and land use change, and increased occurrence of extreme meteorological events. I see great promise for a combination of molecular characterization techniques and (compound specific) C, H, N and O isotope analysis. However, such investigations need to be carried out in close collaboration with in-depth analysis and modeling of the role and response of belowground biodiversity, as well as physical processes such as erosion. Not only to get a complete picture of the processes driving the carbon cycle, but also to be able transcend from the molecular level to higher scale levels. I feel that there is much progress to be made by intensifying such connections.
Closely linked to investigating the carbon cycle is the use of the molecular and/or isotopic signature of soil organic matter as proxy, or biomarker, in environmental reconstructions. Such studies are essential to unravel the response of ecosystems to environmental change, be it anthropogenic or natural. On the other hand, studies of transformations of soil organic matter are needed to assess the stability and applicability of molecular / isotopic proxies in soils. My research within the RUFLE project showed the potential of advancement in this area by the development and use of new analytical techniques, both molecular chemical (biomarker analysis) and computational (the VERHIB model). There is great potential to further develop and apply such proxies, and great interest for such proxies from the paleo-ecological and geo-archaeological communities. An exciting expansion would be the combination with the emerging application of biological proxies such as the use of ancient DNA. Again process based understanding of molecular transformations is needed to assess the applicability.
Click the link below for a short video of exploratory fieldwork in St. Eustatius in December 2012 in search of suitable records for biomarkers together with colleagues from the Paleo-ecology research group and Geo-archaeologists from SECAR.