Methane is a potent greenhouse gas with ever-rising atmospheric concentrations. While anthropogenic sources are comparably well understood, it is still a major scientific challenge to understand and quantify the contribution of natural sources. One reason for this knowledge gap is that (bio)geochemical and geological controls on methane dynamics in aquatic and terrestrial systems as well as the spatial distribution of methane in marine and aquatic sediments, soils and permafrost areas is not well constrained.
The topics of the session will include:
- methane formation (biological and geological processes
- subsurface fluid flow and methane/hydrocarbon transport mechanisms
- ‘marine’ methane-rich systems: e.g. gas hydrates, shallow gas, cold seep-related systems
- ‘terrestrial’ methane-rich systems: e.g. wet lands (natural & artificial), lakes (from puddles to inland seas), permafrost areas and rivers
- methane-associated (bio)geochemical reactions, microbial communities and food web structures
- methane-derived carbonates and microbe-mineral interactions
- monitoring of methane emission
- methane in paleo environments

The session will highlight the significance of (geo)physical, geological, (bio/geo)chemical and (micro)biological controls on methane release in ocean, permafrost, wetlands, lake and river environments.
We will also discuss recent advances on gas hydrate properties & occurrences in sediments.
We aim at gathering scientists from the fields of geology, (bio/geo)chemistry, (geo)physics, modeling, (micro)biology and ecology, to evaluate our current knowledge of aquatic and terrestrial methane dynamics, interactions between element cycles and ecosystems, environmental controls and mechanisms.
A further intention is to create synergies between marine and terrestrial sciences for a multifaceted view on methane dynamics.
This session is also an invitation to scientists from the wider field of environmental geo- and/or bio-engineering dealing with natural methane emissions as an alternative energy source.
We also welcome specialists designing instruments for monitoring methane.

Mineral nucleation and growth processes are well studied for material science and industry applications under controlled laboratory conditions, but our understanding of these complex multistage pathways in natural environments is still rather incomplete. Monitoring precise and quantitative environmental parameters over long time periods is often difficult, imposing great uncertainties on growth processes and physicochemical properties of minerals used to reconstruct Earth’s history, such as microbialites, speleothems, or authigenic cements. Recent findings suggest that nano-clusters, colloidal particles, organic matter or microbes may be fundamental to nucleation and growth processes, especially if kinetics are sluggish at Earth surface temperatures. Thus, it is imperative to investigate mineral formation at the nano- and micro-scale within a broad, interdisciplinary perspective.
In this session we welcome oral and poster presentations from multiple fields including sedimentology, mineralogy, geochemistry, physical chemistry, biology and engineering that contribute to a better understanding of mineral nucleation and growth processes. Contributions may include process-oriented studies in modern systems, the ancient rock record, experiments, computer simulations, and high-resolution microscopy and spectroscopy techniques. We intend to reach a wide community of researchers sharing the common goal of improving our understanding of the fundamental processes underlying mineral formation, which is essential to read our Earth’s geological archive.

In spring and summer 2018, Central and Northern Europe faced a severe drought with rainfall deficits beginning as early as April and lasting until late August in some regions (partly combined with a heat wave in July and August). Due to higher spring temperatures and high radiation the Baltic Sea showed a very unusal low pCO2 signal since late April and a spectacular summer bloom this year. The impact on terrestrial ecosystems became obvious through crop failure and forest fires. This transdiciplinary session calls for scientific results from Earth Observation showing the impact of the drought and for presentations from the interface between science a climate action e.g. adaptation strategies, questions on measuring, reporting and verification of inventories or general communication of climate change to societies.

During the past decades numerous sediment records have become available from lakes and paleolakes through shallow and (ICDP) deep drilling. These records have proven to be valuable archives of past climate and environmental change, and tectonic and volcanic activity. We invite contributions emphasizing quantitative and spatial assessments of rates of change, causes and consequences of long- and short-term climate variability, impact, magnitude, and frequency of tectonic and volcanic activity as deduced from sedimentological, geochemical, biological, and chronological tools.

Solicited speaker: Christine Y. Chen (MIT, USA): “Establishing robust lake sediment chronologies: Lessons from U/Th dating the deep drill core from Lake Junín, Peru”

Soils host a vast biodiversity across various kingdoms, with multiple interactions within and between communities and with the surrounding environment. In this session, we will investigate how biodiversity in soils responds on biotic and abiotic factors across various spatial scales. We will study the functional roles of these communities in processes like nutrient and water cycling, trace gas exchange with the atmosphere, soil erosion, mineral weathering, and vascular plant germination and growth. We will put one special focus on extracellular polymeric substances (EPS) and their role in promoting microbial adhesion to surfaces, reducing cellular desiccation, protecting against antibiotics or toxic molecules, and even acting as a final source of nutrition under extreme scarcity. The amount, composition and functionality of EPS in soils, biological soil crusts, sediments or other porous media will be investigated. Responses of soil communities to land use and climate change as well as other potential threats will also be included in this session. Besides temperate soil communities, we will focus on biological soil crusts occurring in hot and cold deserts around the world, and biofilms forming in coastal regions of freshwater and marine environments.

Hydrothermal systems, mud volcanoes, hybrid environments such as sediment-hosted hydrothermal systems and piercement structures in general are among the most spectacular geological phenomena on Earth. Several studies demonstrated that these structures play a key role in the evolution of our planet and the cycles of life during several geological eras. Active piercements are usually characterized by deep-rooted plumbing systems and complex geochemical reactions where life can adapt to thrive in extremely harsh environments making them ideal targets for deep biosphere exploration. The geophysical signals associated to such environments are often ambiguous and difficult to interpret. The elevated pore pressures often encountered at depth and the high flow rates make these structures ideal natural laboratories to capture precursors of seismic events and dynamically triggered geological processes. Piercement structures have often been reported to respond to earthquakes and external forcing.

This session welcomes contributions from geophysical, geochemical, microbial, geological, numerical and laboratory studies to promote a better understanding of modern and palaeo piercement phenomena. In particular we call for studies related to 1) investigations controlling pre-existing geological structures; 2) the geochemical reactions occurring at depth and at the surface including microbiological studies; 3) the investigation of such systems with geophysical methods; 4) experimental and numerical studies; 5) the survey and the monitoring of these settings and environments to learn the dynamics of the extinct systems from the active ones; 6) the study of palaeo piercements as well as their effects on palaeo climate.