Kai Uwe Totsche

Kai Uwe Totsche
Friedrich Schiller University Jena | FSU · Institute of Geoscience, Department of Hydrogeology

University-Professor Dr.

About

292
Publications
68,930
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Introduction
Kai Uwe Totsche is Professor and head of the Hydrogeology Group, Friedrich-Schiller-University, Germany. We do research in Environmental Nanobiogeochemistry, Subsurface Critical Zone and Groundwater. Our scientific approach comprises field, lab, and numerical methods with focus on structure-function relations, interactions at biogeochemical interfaces, and origin & fate of mobile (organic) matter including microorganisms with special emphasis on the vastly ignored colloidal/suspended fractions.

Publications

Publications (292)
Article
Full-text available
Background To better understand the influence of habitat on the genetic content of bacteria, with a focus on members of Candidate Phyla Radiation (CPR) bacteria, we studied the effects of transitioning from soil via seepage waters to groundwater on genomic composition of ultra-small Parcubacteria , the dominating CPR class in seepage waters, using...
Preprint
Full-text available
Anthropogenic activities cause the release of vast amounts of contaminants into the environment which eventually reach even groundwater resources. With usually sparse regulatory monitoring of limited priority compounds, the large spectrum of contaminants, and the intricacies of intra- and inter-annual contaminant dynamics, such as the emergence and...
Preprint
Full-text available
Ignoring the diurnal cycle in surface-to-atmosphere CO2 fluxes leads to a systematic bias in CO2 mole fraction simulations sampled at daytime, because the daily mean flux systematically misses the CO2 uptake during the daytime hours. In an atmospheric inversion using daytime-selected CO2 measurements at most continental sites and not resolving diur...
Article
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The development of soil structure and its linkage to functions have become a major research theme boosted by the increasing threat to soil health and fertility due to climate and land-use changes. Water retention, flow of fluids, matter dispersal, habitat provision, nutrient supply, organic matter and element storage are functions of soil fundament...
Preprint
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Atmospheric transport models are often used to simulate the distribution of greenhouse gases (GHGs). This can be in the context of forward modelling of tracer transport using surface-atmosphere fluxes, or flux estimation through inverse modelling, whereby atmospheric tracer measurements are used in combination with simulated transport. In both of t...
Article
Full-text available
The functions of soils are intimately linked to their three-dimensional pore space and the associated biogeochemical interfaces, mirrored in the complex structure that developed during pedogenesis. Under stress overload, soil disintegrates into smaller compound structures, conventionally named aggregates. Microaggregates (<250 μm) are recognized as...
Article
Full-text available
Background Our understanding of C storage in soils lacks insights investigating organic matter (OM) depletion, often studied in bare fallow systems. The content of coarse rock fragments is often excluded, whereas it may affect C storage. Aims We aim to contribute to a better understanding of the impact of bare fallow on C storage mechanisms in the...
Article
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Background The terrestrial subsurface is home to a significant proportion of the Earth’s microbial biomass. Our understanding about terrestrial subsurface microbiomes is almost exclusively derived from groundwater and porous sediments mainly by using 16S rRNA gene surveys. To obtain more insights about biomass of consolidated rocks and the metaboli...
Article
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Background: Soil organisms influence pedogenesis on a molecular level through the production of biopolymers which interact with soil minerals depending on their molecular properties. Specifically, biopolymers impact structure formation by inhibiting aggregation as a separation agent or promoting aggregation as a bridging agent. Mucus is a biopolym...
Preprint
To better understand the influence of habitat on the genetic content of Candidate Phyla Radiation (CPR) bacteria, we studied the effects of transitioning from soil to groundwater on genomic divergences of these organisms. Bacterial metagenome-assembled genomes (318 total, 35 of CPR bacteria) were generated from seepage waters and compared directly...
Article
Full-text available
Soil biogeochemistry is intrinsically coupled to the redox cycling of iron and manganese. Oxidized manganese forms various (hydr)oxides that may reductively transform and dissolve, thereby serving as electron acceptors for microbial metabolisms. Furthermore, manganese oxides might reduce purely abiotically by oxidation of dissolved Mn2+ in a specif...
Article
Full-text available
We present an analysis of atmospheric transport impact on estimating CO2 fluxes using two atmospheric inversion systems (CarboScope-Regional (CSR) and Lund University Modular Inversion Algorithm (LUMIA)) over Europe in 2018. The main focus of this study is to quantify the dominant drivers of spread amid CO2 estimates derived from atmospheric tracer...
Article
Full-text available
Soil aggregation and the translocation of clay and organic matter are significant pedogenic processes that manifest in diagnostic horizons in mature soil. Yet, their onset might date to much earlier stages of soil development where host rock weathering is dominant and litter from pioneer vegetation is the only input of organic matter. We present a...
Article
Microaggregates (<250 µm) are key structural subunits of soils. However, their formation processes, rates, and transformation with time are poorly understood. We took advantage of multiple isotope labelling of potential organic gluing agents and inorganic building units to unravel their role in soil aggregation processes being initiated with and wi...
Preprint
Full-text available
The terrestrial subsurface houses a significant proportion of the Earth’s microbial biomass. Our understanding about terrestrial subsurface microbiomes is almost exclusively derived from groundwater and porous sediments. To obtain more insights about endolithic microbiomes and their metabolic status, we investigated rock samples from the vadose zon...
Preprint
Full-text available
We present an analysis of atmospheric transport impact on estimating CO2 fluxes using two atmospheric inversion systems (CarboScope Regional (CSR) and LUMIA) over Europe for 2018. The main focus of this study is to quantify the dominant drivers of spread amid CO2 estimates derived from atmospheric tracer inversions. The Lagrangian transport models...
Article
Full-text available
Understanding the sources, structure and fate of dissolved organic matter (DOM) in groundwater is paramount for the protection and sustainable use of this vital resource. On its passage through the Critical Zone, DOM is subject to biogeochemical conversions. Therefore, it carries valuable cross-habitat information for monitoring and predicting the...
Article
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Earthworms and (tap-)roots impact the soil structure by creating large biopores, affecting infiltration capacity, seepage, nutrient cycling, and soil aeration. Despite the importance of biopores for the functions of soils and the fact that several hundreds of biopores >2 mm in diameter may occur on one square meter of soil, knowledge on the interde...
Article
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Three-hourly net ecosystem exchange (NEE) is estimated at spatial scales of 0.25∘ over the European continent, based on the pre-operational inverse modelling framework “CarboScope Regional” (CSR) for the years 2006 to 2019. To assess the uncertainty originating from the choice of a priori flux models and observational data, ensembles of inversions...
Preprint
Full-text available
Analysis of 5 years metabolomics data for groundwater, at 7 sampling sites across a hillslope aquifer system. The study uses particularly principal component analysis (PCA) of LCMS-data to show that the highly variable metabolome is driven by water flows, and traces those in inter-well comparisons.
Article
Microaggregates are hot spots of microbial activity at a scale that frequently poses a severe experimental challenge or defies a direct observation. Mathematical models that combine the mechanisms of spatially resolved organic matter transport with the processes of organic matter turnover can facilitate the understanding of soil microbial dynamics...
Article
Microaggregates (<250 μm) are key structural subunits of soils. However, their formation processes, rates, and transformation with time are poorly understood. We took advantage of multiple isotope labelling of potential organic gluing agents and inorganic building units to unravel their role in soil aggregation processes being initiated with and wi...
Preprint
Full-text available
3-hourly Net Ecosystem Exchange (NEE) is estimated at spatial scales of 0.25 degrees over the European continent, based on the pre-operational inverse modelling framework CarboScope Regional (CSR) for the years 2006 to 2019. To assess the uncertainty originating from the choice of a-priori flux models and observational data, ensembles of inversions...
Article
Full-text available
Soil organisms are recognized as ecosystem engineers and key for aggregation in soil due to bioturbation, organic matter (OM) decomposition, and excretion of biogenic OM. The activity of soil organisms is beneficial for soil quality, functions, and nutrient cycling. These attributions are based on field-scale observations that link the presence and...
Article
Full-text available
Temporal evolution of element ratios in the catchment of the River Thuringian Saale A literature retrieval was performed for a total of about 5491 datasets of whole rock geochemical analyses of sedimentary, magmatic and metamorphic rocks in the catchment of River Thuringian Saale for the past 600 Ma. Considering availability and coincidence with p...
Article
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Engineered humic acid-coated goethite (HA-Goe) colloids find increasing application in in situ remediation of metal(loid)-polluted groundwater. Once introduced into the subsurface, the colloids interact with groundwater altering their physicochemical properties. In comparison to freshly synthesized, unreacted HA-Goe colloids, such alterations could...
Article
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Time series analyses are a crucial tool for uncovering the patterns and processes shaping microbial communities and their functions, especially in aquatic ecosystems. Subsurface aquatic environments are perceived to be more stable than surface oceans and lakes, due to the lack of sunlight, the absence of photosysnthetically-driven primary productio...
Preprint
Full-text available
Mathematical models that combine the mechanisms of organic matter transport in a pore space with the processes of organic matter turnover can facilitate the understanding of soil microbial dynamics and function of soils at scales still inaccessible for experiments. In this study, we investigate microbial population dynamics and the turnover of par...
Preprint
Full-text available
Time series analyses are a crucial tool for uncovering the patterns and processes shaping microbial communities and their functions, especially in aquatic ecosystems. Subsurface aquatic environments are perceived to be more stable than oceans and lakes, due to the lack of sunlight, the absence of photosysnthetically-driven primary production, low t...
Article
Full-text available
Colloidal settlement in natural aqueous suspensions is effectively compensated by diffusive movement if particles resist aggregation – a state known as colloidal stability. However, if the settling velocity increases upon aggregation, complex structural features emerge from the directional movement induced by gravity. We present a comprehensive mod...
Article
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Surface-sourced organic compounds in infiltrating waters and percolates are transformed during their belowground passage. Biotic and abiotic processes thereby lead to continuously changing chemical environments in subsurface compartments. The investigation of such transformations of organic compounds aims for tracing subsurface fluxes as well as bi...
Article
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Hypothesis A prominent fraction of mobile organic matter in natural aqueous soil solutions is formed by molecules in sizes that seamlessly exceed the lower end of what is defined as a colloid. The hydrodynamics and the functional diversity of these molecules result in a transport behavior that is fundamentally different from smaller compounds. Howe...
Article
Full-text available
Considerable portions of the total mobile inventory of soil seepage are the diverse colloidal and larger suspended materials that essentially contribute to pedogenesis, soil functioning, and nutritional supply of subsurface ecosystems. However, the size- and material-spectra of the total mobile inventory, and field-scale factors controlling its lon...
Article
Full-text available
Forecasting atmospheric CO2 concentrations on synoptic timescales (∼ days) can benefit the planning of field campaigns by better predicting the location of important gradients. One aspect of this, accurately predicting the day-to-day variation in biospheric fluxes, poses a major challenge. This study aims to investigate the feasibility of using a d...
Article
Full-text available
Earthworms are considered as “ecosystem engineers” impacting soil properties as well as nutrient and element cycles. As they move through soil, earthworms secrete cutaneous mucus which is metabolized by soil microorganisms and a source of plant-available nutrients. Earthworm-processed soil contains carbon enriched, earthworm-specific soil aggregate...
Article
High inputs of easily available organic matter to the subsurface may quickly activate the native microbial communities, thereby changing soil engineering properties. We studied the effect of glucose addition, an easily available carbon source, on stress-strain properties, mineralogy, and microstructure of several loamy and sandy soils over 30 days...
Article
Full-text available
Surface ecosystems are rapidly changing on a global scale and it is important to understand how this influences aquifers in the subsurface, as groundwater quality is a major concern for future generations. Dissolved organic matter (DOM) contains molecular and isotopic signals from surface-derived inputs as well as from the biotic and abiotic subsur...
Poster
Full-text available
Anthropogenic inputs of nitrate into groundwater pose a considerable risk to drinking water quality. However, groundwater chemistry is also affected by continued in situ microbial nitrate formation and nitrate reduction to gaseous nitrogen. Here, we investigated nitrogen transformation processes and their microbial key players in oligotrophic karst...
Article
Full-text available
Soil functions are closely related to the structure of soil microaggregates. Yet, the mechanisms controlling the establishment of soil structure are diverse and partly unknown. Hence, the understanding of soil processes and functions requires the connection of the concepts on the formation and consolidation of soil structural elements across scales...
Article
Full-text available
Groundwater ecosystems face the challenge of energy limitation due to the absence of light-driven primary production. Lack of space and low oxygen availability might further contribute to generally assumed low food web complexity. Chemolithoautotrophy provides additional input of carbon within the subsurface, however, we still do not understand how...
Article
Hydrodynamics drives both stochastic and deterministic community assembly in aquatic habitats, by translocating microbes across geographic barriers and generating changes in selective pressures. Thus, heterogeneity of hydrogeological settings and episodic surface inputs from recharge areas might play important roles in shaping and maintaining groun...
Article
Multi-directional fluid flow and transport dynamics as intrinsic characteristics of hillslope flow regimes can strongly contribute to the quality evolution of groundwater resources and compartmentalization of subsurface ecosystems. However, their extent and importance in topographic highs (groundwater recharge areas) is typically less investigated,...
Article
Full-text available
Forecasting atmospheric CO2 concentrations on synoptic time scales (~ days) can benefit the planning of field campaigns by better predicting the location of important gradients. One aspect of this, accurately predicting the day-to-day variation in biospheric fluxes poses a major challenge. This research aims to investigate the feasibility of using...
Article
Full-text available
Despite the widely observed predominance of Cand. Patescibacteria in subsurface communities, their input source and ecophysiology are poorly understood. Here we study mechanisms of the formation of a groundwater microbiome and the subsequent differentiation of Cand. Patescibacteria. In the Hainich Critical Zone Exploratory, Germany, we trace the in...
Article
Full-text available
Across a landscape, aquatic-terrestrial interfaces within and between ecosystems are hotspots of organic matter (OM) mineralization. These interfaces are characterized by sharp spatio-temporal changes in environmental conditions, which affect OM properties and thus control OM mineralization and other transformation processes. Consequently, the exte...
Article
Vein mineralization observed in boreholes, quarries and outcrops of Upper Permian and Mesozoic sediments in the Thuringian Syncline, Germany, was investigated for the first time by petrography, electron microprobe analysis and stable isotope analysis. The objective was a characterization of paleo-fluid systems within this basin. Veins are mostly re...
Conference Paper
Full-text available
Finding interlinkages between soil chemistry, microstructure and microbial communities in the contaminated soils is a fundamental requirement to assess their remediation strategy. We studied composition, microstructure and microbial communities of an aged tar oil contaminated technosol on a former manufactured gas plant site in Germany. The soil co...
Article
Terrestrial subsurface microbial communities are not restricted to the fluid-filled void system commonly targeted during groundwater sampling but are able to inhabit and dwell in rocks. However, compared to the exploration of the deep biosphere, endolithic niches in shallow sedimentary bedrock have received little interest so far. Despite the poten...
Article
Full-text available
Despite the global significance of the subsurface biosphere, the degree to which it depends on surface organic carbon (OC) is still poorly understood. Here, we compare stable and radiogenic carbon isotope compositions of microbial phospholipid fatty acids (PLFAs) with those of in situ potential microbial C sources to assess the major C sources for...
Article
Full-text available
Determining the biogeochemical pathways utilized by microbes living in groundwater is essential for understanding the subsurface C cycle and the fate of organic compounds, including pollutants. The radiocarbon signature (Δ ¹⁴ C) of fatty acid methyl esters derived from microbial phospholipids (PLFA) provides useful information for differentiating m...
Article
Full-text available
The functions of soils are intimately linked to its aggregated structure. Microaggregates formed during pedogenesis from a vast variety of mineral, organic, and biotic materials are the smallest conceivable compounds at the basis of soil structural hierarchy. Qualitative hypotheses and concepts on how aggregates form are quite elaborate, but the co...
Conference Paper
An intensive flight campaign, CoMet (Carbon dioxide and Methane Mission), was conducted during May and June 2018, with the aim to better understand important sources of carbon dioxide (CO2) and methane (CH4) in Europe as well as to test and validate the newly developed Integrated Path Differential Absorption (IPDA) Lidar CHARM-F operated by DLR. On...
Article
Full-text available
Structures of colloidal compounds in soil, including organo–mineral and mineral–mineral associations, are considered as composite building units (CBUs) that may combine into soil microaggregates. Despite the ubiquitous occurrence of CBUs, the major formation mechanisms are rather obscure and little is known about whether they form primarily during...
Article
Structural hierarchy is a fundamental characteristic of natural porous media. Yet it provokes one of the grand challenges for the modeling of fluid flow and transport since pore‐scale structures and continuum‐scale domains often coincide independent of the observation scale. Common approaches to represent structural hierarchy build, for example, on...
Article
Groundwater ecosystems host diverse and complex microbial communities that play important roles in the biogeochemical processing of organic matter and in the maintenance of drinking water quality. Here we investigated the microbial community in suspended particulate matter (SPM) of biogeochemically distinct groundwaters (Hainich Critical Zone Explo...
Article
Full-text available
Structure formation and self organization in soils determine soil functions and regulate soil processes. Mathematically based modeling can facilitate the understanding of organizing mechanisms at different scales, provided that the major driving forces are taken into account. In this research we present an extension of the mechanistic model for tra...