ERC FUNDED PROJECTS

The recent anthropogenic global warming makes a detailed understanding of coupling processes between climate and biogeochemical cycles of pressing importance. The atmospheric archive of air bubbles enclosed in polar ice cores provides the only direct record of greenhouse gas changes in the past, and the key to understanding the related changes in biogeochemical cycles and climate/greenhouse gas feedbacks. Crucial questions about greenhouse gas variability on very short (decadal) and very long (orbital) time scales still remain open. To answer these questions, the ice core community has proposed new drilling projects with the goal of nearly doubling the time span of the available ice core record to the last 1.5 million years and of covering the entire Holocene greenhouse gas record in unprecedented decadal resolution. These goals have one thing in common: due to glacier flow most of this record will only be found in a very thin layer in the bottom-most ice of the cores. Completely new analytical approaches are needed to unlock the atmospheric archive in this ice in order to gain high-resolution, high-precision measurements, while at the same time drastically reducing sample consumption compared to established techniques. The deepSLice project will make such a step change in ice core analytics by developing a novel coupled Continuous Sublimation Extraction-Quantum Cascade Laser Spectrometer system. It will allow us to simultaneously measure CO2, CH4 and N2O concentrations as well as the isotopic composition of CO2 on air samples of only 1-2 ml at standard pressure and temperature, reducing the required sample size by one order of magnitude. This non-destructive analysis will make it also possible for the complete air sample to be recollected after analysis and used for other measurements. This method will be applied to existing and new ice cores in order to study past changes in greenhouse gases and the underlying biogeochemical cycles in unparalleled detail.

2 255 788 €

Start date: 2015-10-01, End date: 2020-09-30

How are deep mantle processes related to the mapped geological record? How can we reconcile geochemical observations with geophysical inferences? These are first order unanswered questions despite our steady progress in imaging the Earth's internal structure and understanding the high temperature and pressure properties of minerals. To make a breakthrough, we have to understand solid-state convection in the Earth's mantle in much greater detail. Much is known about the physical processes, such as melting and the delicate interaction between thermal and chemical buoyancy, but the parameters that enter their mathematical description are not very well known. Once these parameters are determined, the thermo-chemical evolution of our planet can self-consistently be modelled. The state-of-the-art is to roughly estimate these parameters and qualitatively compare the modelling to some relevant geophysical, geochemical or geological observations. This comparison is not comprehensive and never explains all observables. We propose a radically new approach, where all observables are used together to infer these parameters directly, using a fully non-linear Bayesian inference technique based on neural networks. This will determine for the first time the initial conditions at the Earth's formation, the Earth-like flow parameters essential to model the thermo-chemical evolution of our planet and produce models that are simultaneously consistent with the main different geophysical and geochemical datasets.

3 480 600 €

Start date: 2013-05-01, End date: 2018-04-30

IRMIDYN will study the dynamics of redox-driven iron mineral transformation processes in soils and sediments and impacts on nutrient and trace element behavior using a novel approach based on enriched stable isotopes (e.g., 57Fe, 33S, 67Zn, 113Cd, 198Hg) in combination with innovative experiments and cutting-edge analytical techniques, most importantly 57Fe Mössbauer and Raman micro-spectroscopy and imaging. The thermodynamic stability and occurrence of iron minerals in sufficiently stable Earth surface environments is fairly well understood and supported by field observations. However, the kinetics of iron mineral recrystallization and transformation processes under rapidly changing redox conditions is far less understood, and has to date mostly been studied in in mixed reactors with pure minerals or sediment slurries, but rarely in-situ in complex soils and sediments. Thus, we do not know if and how fast certain iron mineral recrystallization and transformation processes observed in the laboratory actually occur in soils and sediments, and which environmental factors control the transformation rates and products. Redox-driven iron mineral recrystallization and transformation processes are key to understanding the biogeochemical cycles of C, N, P, S, and many trace elements (e.g., As, Zn, Cd, Hg, U). In face of current global challenges caused by massive anthropogenic changes in biogeochemical cycles of nutrients and toxic elements, it is paramount that we begin to understand and quantify the dynamics of these processes in-situ and learn how we can apply our mechanistic (but often reductionist) knowledge to the natural environment. This project will take a large step toward a better understanding of iron mineral dynamics in redox-affected Earth surface environments, with wide implications in biogeochemistry and other fields including environmental engineering, corrosion sciences, archaeology and cultural heritage sciences, and planetary sciences.

3 154 658 €

Start date: 2018-11-01, End date: 2023-10-31

There is a need for a radically new laboratory experimental approach for studying the interaction of seismic waves with the complex media of the Earth’s subsurface. We present here a fundamental new approach to seismic wave experimentation that involves fully immersing a physical seismic experiment within a virtual numerical environment. This enormously challenging endeavour, which is relevant to many outstanding issues in seismology, has not been previously attempted. By continuously varying the output of numerous transponders closely spaced around the physical domain using a control algorithm that takes advantage of measurements made by a scanning Laser-Doppler Vibrometer and a novel theory of exact boundary conditions, waves travelling between the physical and numerical domains will seamlessly propagate back and forth between the two domains without being affected by reflections at the boundaries between the two domains. This will allow us to investigate diverse types of Earth materials using frequencies that are much closer to those of seismic waves propagating through the Earth than previously possible. The novel laboratory enables experimentation under highly controlled conditions. A broad range of long-standing problems in wave propagation and imaging that have eluded Earth scientists and physicists for decades will be addressed. Fine scale heterogeneity, porosity and fluid saturation in real Earth media result in complex frequency-dependent amplitude and phase responses that we can characterize in the laboratory. Synthetically produced complex models can be used in wavefield-focussing experiments and to achieve complete elastic time-reversal for the first time ever. We will study coda waves that can be indicative of slight changes in stress fields before catastrophic fracturing and that might provide pre-cursory signs of earthquakes. Finally, the laboratory is highly relevant to applications such as non-destructive testing, medical imaging and lithotripsy.

3 498 330 €

Start date: 2016-12-01, End date: 2021-11-30