Abstracts of contributions to the NGL Annual Science Meeting 2013 are presented below. The conference abstracts are also available for download in a single file: pdf
Where applicable, presentations are available by clicking the link after each presenter name.

Geobiology

Distribution of sulphate-reducing bacteria and Archaea in Äspö groundwater

Karsten Pedersen, Chalmers – presentation

The Äspö groundwater has varying groundwater types over depth and position. Presence and activity of sulphate-reducing bacteria (SRB) have been studied with cultivation and DNA techniques since start of construction. The most obvious result was the large abundance of cultivable sulphate-reducing bacteria (SRB), at varying positions along the tunnel which correlated with the origin and composition of groundwater. The sulphate-reducing bacterium Desulfovibrio aespoeensis was isolated from about 450 m depth and it has been repeatedly cultured from 300-450 m. It was found in a 454 pyrosequence abundance of 11 % to species level in a borehole at 450 m. In opposite, the deepest Äspö sample from 460 m was totally free from SRB related sequences. The 454 DNA data correlated very well with geochemistry and cultured diversity. Archaea sequences were sparsely detected. Bacteriophages are suggested to be important in the control presence and activity of SRB.

Life in the deep – systems biology to unlock novel microbial species, active populations, and unique metabolic pathways

Xiaofen Wu, Linneaus University

Although the deep biosphere experience scarcity of carbon and energy sources, a large proportion of all the present bacteria and archaea residing in this seemingly hostile environment appear to be alive and metabolically active. However, the details of the diversity and metabolism of the microorganisms in this environment are still poorly understood. The current study is being carried out at the Äspö Hard Rock Laboratory (HRL) in order to describe the micriobiome of the terrestrial deep biosphere by using community DNA (metagenome) and RNA (metatranscriptome) sequencing. In contrast to our current inability to cultivate the majority of the microorganisms residing in the deep biosphere, our molecular approaches target all resident populations at a high level of detail and with minimal bias. Four sampling sites were chosen for DNA- and RNA-based community sequencing of the dominant water types; meteoric, marine, deep saline, and a mixed. The study will give a better understanding of microbial life in the deep biosphere and how the cells obtain energy for maintenance and growth in this extremely oligotrophic environment. Additionally, we will describe differences in the microbial community structure compared to the surface community, and inform about potential genetic exchange between species. The study will also examine which members of the community are active, how these species are adapted to this environment, and how the microbial populations might respond to future environmental change. The metagenomic and metatranscriptomic analyses will be combined with contextual information about the chemistry, geology, and hydrology of the deep subsurface with the broad aim of creating a complete model to understand the role of microorganisms in natural groundwater systems.

High resolution characterization of recent and ancient microbial systems in the Äspö Hard Rock Laboratory

Christine Heim, Geoscience Centre Göttingen, Germany – presentation

The recent subsurface biosphere in the Äspö HRL was used as a model system to characterize microbial biosignatures and their relation to fluid composition and mineral fabrics within fractures. For the study of inorganic biosignatures produced by sulfate reducing bacteria (SRB) and iron oxidizing bacteria (FeOB), microscopy and laser ablation inductively coupled mass spectrometry were used to investigate fine-scale biomineralization processes and trace and rare earth element (TREE) fractionations and accumulations. The TREE accumulation in the mineralized FeOB containing mat conserved the TREE pattern of the feeder fluid, thereby reflecting the fluid composition throughout the activity of the microbial mat. In contrast, the SRB containing mat showed a fractionation of TREE that significantly differed from the pattern of the FeOB as well as the aquifer water, and may thus constitute a distinctive biosignature. Furthermore, an innovative analytical approach including Time-of-Flight-Secondary Ion Mass Spectrometry enabled the detection of biosignatures for microbial communities in vein minerals as potential archives for a fossil deep biosphere.

 

(Bio)geochemistry

Rare earth elements in groundwater and low-temperature calcites in fractures of crystalline rock

Mats Åström, Linneaus University

Rare earth elements (REE) occurring in the fracture network of granitoids in Laxemar and Forsmark are investigated, including the phases dissolved in water and residing in solid materials precipitated on the fracture walls. Overall, the REE concentrations in the waters are low and uncorrelated with the source/character of the water (marine, meteoric, glacial, old-saline) and with the depth of the sampled fractures. In contrast, the REE concentrations are generally abundant in low-temperature calcite precipitates on the fracture walls. The REE pool in these calcites is typically strongly enriched in the light metals of the series when normalized to the REE abundance in wall rock. Comparison of the REE fractionation patterns in the waters and calcites suggest that during the period when the calcites precipitated (last 10 million years), the water in the fractures have had REE to Ca ratios similar to those in the present-day waters.

Critical Zone Observatories: quantifying the chain of impact between biosphere and geosphere

Steven Banwart, University of Sheffield, UK – presentation

Earth’s Critical Zone (CZ) is the thin surface of our planet that extends from the top of the tree canopy to the bottom of drinking water aquifers and supplies most life-sustaining resources.  Increasing human population and wealth are powerful demographic drivers of rapid environmental changes at planetary scale. The predicted increase in human population to over 9.5 billion in the next 40 years establishes a “4×40” global challenges scenario. By 2050: 1) the demand for food will double, 2) the demand for fuel will double, 3) the demand for clean water will increase by more than 60%, while 4) mitigating and adapting to a changing global climate and biodiversity decline.  Major impacts at the continental surface and margins are already arising through climate change and the intensification of land use, biomass production, fisheries, and freshwater extraction. Critical Zone science is a field of interdisciplinary study that identifies and quantifies the mechanistic linkages that propagate the impacts of environmental changes through the CZ.  Fundamental to CZ science is quantification of the integrated flows of material, energy, and genetic information that shape the CZ and support essential economic services.

Critical Zone Observatories (CZOs), advanced field research facilities established during the past 5 years, intensively study the complex interactions of rock, soil, water, air and organisms that regulate CZ properties and their ability to provide life-sustaining resources [1]. CZOs have established scientific focal points that define major research questions, raise awareness of critical zone vulnerability, and interface with environmental policy. They have fostered the interdisciplinary research necessary to rapidly deliver solutions to the major societal challenges of land degradation, climate change, food security, biofuel and shallow geosphere energy production, and a clean and plentiful water supply.

International networks of CZOs offer enormous potential to globally integrate basic science with innovation in human adaptation to rapid and intensive environmental change [2].  Current European CZOs focus on soil vulnerability and basic science advances to translate geospatial properties of Earth’s surface into the process rates that define the key soil functions [3].  Application of the research results is geospatial mapping of soil functions and their vulnerability to land use and land management decisions.  Mathematical modelling provides a quantitative integrating framework for the science advances and applications [4].  Computational simulation describes the coupled processes of fluid flows, reactive transport, carbon and nutrient transformations and ecological food web dynamics. Model outputs are also integrated with life cycle assessment for land use and ecological economics to support land management decisions. This methodology provides one example of a design framework to hypothesise and test solutions for improved CZ management in order to success fully address the 4×40 global challenges.

REFERENCES

[1] Banwart S.A. (2011). Save Our Soils. Nature, 474,151–152.

[2] Banwart, S.A., Chorover, J., Gaillardet, J., Sparks, D., White, T., Anderson, S., Aufdenkampe, A., Bernasconi, S., Brantley, S.L., Chadwick, O., Dietrich, W.L.E., Duffy, C., Goldhaber, M., Lehnert, K., Nikolaidis, N.P., and Ragnarsdottir, K.V. (2013). Sustaining Earth’s Critical Zone Basic Science and Interdisciplinary Solutions for Global Challenges. The University of Sheffield, 47 pages, ISBN: 978-0-9576890-0-8. Available from www.czen.org.

[3] Banwart S.A. and 21 co-authors (2011). Assessing Soil Processes and Function across an International Network of Critical Zone Observatories: research hypotheses and experimental design. Invited contribution to special issue on Critical Zone Observatories, Vadose Zone J., 10, 974–987.

[4] Banwart S.A. and 23 co-authors (2012). Soil processes and functions across an International Network of Critical Zone Observatories: introduction to experimental methods and initial results. Invited contribution to French Academy of Sciences symposium on land erosion and transformation, special issue of Comptes Rendus Geoscience, 344, 758-772.

Modelling of surface complexation sorption with limited data

James Crawford, Kemakta

Mechanistic models of surface complexation are important tools for understanding how sorption of many safety critical radionuclides respond to temporal and spatial changes in groundwater composition. It is difficult, however, to apply customary methods for fitting surface complexation sorption models to laboratory data when dealing with mineralogically and microstructurally complex materials such as granite. It is generally not feasible, for example, to obtain detailed sorption edge measurements for granular materials with long diffusive equilibration times. We have recently developed a hybrid approach for fitting internally consistent surface complexation model parameters to limited measurement data sets. This work has been carried out as part of the Crystalline Rock Retention Processes (CROCK) project within the EU FP7 Framework programme. The model has been preliminarily tested for three different nuclides using laboratory data for Forsmark metagranite and was found to have excellent predictive capability for a groundwater composition outside its range of calibration.

High Cesium Concentrations in  Groundwater in a Coastal Granitoidic Fracture Network

Frédéric Mathurin, Linneaus University

This study aims to increase the understanding of the sources and mechanisms by which elevated Cs concentrations build up naturally in deep and low temperature groundwater residing in fractured crystalline bedrock. The hydrochemical monitoring program carried out by SKB revealed that high variability in natural Cs concentrations, with values up to several μg/L, occurs in fracture groundwater at the Äspö HRL and the Laxemar area down to 1155m depth. Related to the various types of water residing into the bedrock, the highest Cs concentrations were found in both old deep-seated saline and marinogenic groundwater. The SEM-EDS and XRD analyses of fracture coatings reveal that high Cs concentrations (>50ppm) in the bulk fracture coatings correlate with a mineral enrichement in illite. Based on hydrochemical modelling, intrusion of Baltic Sea water, together with cation exchange, constitute a consistent explanation for the high Cs concentrations observed in the marinogenic groundwater at the Äspö HRL.

Using secondary minerals to trace geochemical processes in the deep subsurface

Henrik Drake, Linneaus University – presentation

Extensive studies of minerals precipitated in the rock fractures at Äspö (down to 450 m) and Laxemar (to 1000 m), have revealed processes and past conditions in the fracture systems. Information gained include detection of the near-surface redox front – where conditions change from oxidising to reducing, as well as information on remaining reducing capacity of the rock around the fractures. A sequence of fracture mineralization events have been discerned by relative and direct dating and by isotopic composition, showing both how e.g. temperature and salinity have changed and relation to different geological events. Stable isotopes and trace elements in calcite and pyrite achieved from intra-crystal analyses have been compared to water chemistry in the same fractures and information of depth and activity of sulphate reducing bacteria, fluctuation of the fresh-saline water interface, anaerobic methane oxidation, and chemical stability of the groundwater chemistry under recent low-temperature conditions have been gained.

Geochemistry of calcite veins: records of fluid mixing and fluid-rock interaction

Olga Maskenskaya, Linneaus University

Detailed geochemical study of calcite veins that genetically related to Mezoproterozoic dolerite intrusions has been used to indicate source and evolution of paleofluid that precipitated calcite. The area of investigation is located in south-east of Sweden (the Laxemar) and dominated by 1.85 Ga granitoids. The variation in rare earth and stable isotope composition across calcite veins and presence of two groups of fluid inclusions suggested mixing of hydrothermal fluids that emanated from the dolerite dyke intrusion with brines that resided in the bedrock prior to dyke emplacement.

Fluoride patterns in a boreal catchment influenced by a fluorine-rich granite intrusion

Tobias Berger, Linneaus University

We studied the influence of a fluorine-rich granite intrusion on fluoride concentration in a small boreal catchment, located within the SKB site investigation area north of Oskarshamn. Surface water and shallow groundwater were sampled and analysed in spatial and temporal dimensions. Fluoride increased strongly towards the lower reaches of the catchment, just south of the intrusion, and at the stream outlet concentrations were 1.6–4.7 times higher than upstream (maximum concentration was 4.2 mg/L). Concentrations were particularly elevated in groundwater and small surface-water bodies (including quarries) above or in direct contact with the granite (maximum 5.3 mg/L). The granite most likely delivers fluoride to the stream by (1) weathering of the fine fraction of glacial deposits derived from the granite and associated fluorine-rich greisen alterations (2) a large relative input of baseflow into the lower reaches and (3) through water-conducting fracture zones running through the fluorine-rich granite and greisen.

Impacts of aqueous carbonate accumulation rate, magnesium and polyaspartic acid on calcium carbonate formation (6 – 40°C)

Stephan Köhler, SLU

The formation of anhydrous CaCO3 polymorphs is very common and widespread in low-temperature inorganic and biogenic environments. An increase in aqueous carbonate concentration frequently induces CaCO3 formation in nature. Nevertheless, few systematic experiments have assessed the impact of the continuous accumulation of aqueous carbonate ions on CaCO3 formation. In particular, the coupled influences of temperature, inorganic and organic additives, and rates of aqueous carbonate accumulation and supersaturation to induce CaCO3 polymorph formation have been poorly investigated. The latter two factors comprise reaction times that are required for nucleation and subsequently affect the precipitation kinetics through ongoing CaCO3 formation. To address these issues, CaCO3 formation was experimentally studied at a variety of aqueous carbonate accumulation rates (10-1.5 ≤ ACAR ≤ 101.8 µmol h-1 l-1) between 6 and 40 °C using a CO2 diffusion technique at conditions that were analogous to sea water (pH 8.3; [Ca2+] = 10 mmol l-1). The impacts of an inorganic and organic constituent on CaCO3 formation were investigated using Mg2+ and polyaspartic acid (Pasp) at concentrations up to 55 mmol l-1 and 3.4 mg l-1, respectively. The experimental data clearly reveal that the time for CaCO3 nucleation depends strongly on ACAR, T, [Mg2+] (>0.5 mmol l-1), and [Pasp] (> 0.1 mg l-1) but not on the formation of different CaCO3 polymorphs. Elevated ACAR results in earlier CaCO3 formation and causes Mg2+ to have less of an impact on the retardation of nucleation. The ion activity product (IAP) required for CaCO3 nucleation is positively correlated to the subsequent CaCO3 precipitation rates but is independent of whether aragonite or calcite formation is induced. The type of CaCO3 polymorph from the primary nuclei is controlled by the influences of Mg2+ and Pasp, which are coupled to ACAR and T. Elevated ACAR, T, and [Mg2+] promote the formation of aragonite, and high [Mg2+] levels suppress the formation of vaterite. In contrast, [Pasp] > 0.02 mg l-1 inhibits aragonite and favours vaterite formation. Thus, if both Mg2+ and Pasp are present, the formation of calcite is favoured. The precipitation rates for ongoing calcite and aragonite formation are nearly the same at analogous conditions and particularly for a given IAP. According to our experimental results, the combined impacts of ACAR, T, [Mg2+], and [Pasp] must be considered to identify distinct conditions of CaCO3 polymorph formation and precipitation kinetics.

Fractionation of Trace Elements and Isotopes during Crystallization of Calcium Carbonates in Aquatic Systems – Experiments and Applications.

Martin Dietzel, Graz University of Technology, Austria – presentation

This talk will give an overview of a large number of experimental studies undertaken at the TH GRAZ, (Austria) on how trace elements distribution and isotope signals can be used to decipher rates and polymorph type of CaCO3 formation in aqueous solutions rich in carbonate.

 

Pollutant transport–remediation

What are the benefits of using radioactive tracers?

Mats Skålberg, Johan Byegård, Sanne Höglund, Eva Selnert, Peter Andersson, Kersti Nilsson and Erik Gustavsson, Geosigma

Several experiments have been performed in Äspö HRL using radioactive tracers in order to study transport, sorption and other chemical reactions. The use of radioactive tracer techniques for studies of many other issues might be applicable in the framework of the National Geosphere Laboratory, NGL.

There are several advantages using radioactive tracers when considering field experiments:

1. The tracer will disappear due to radioactive decay
2. Radioactivity is generally easy to measure
3. High specific activity offers in many cases the possibility to obtain a large dynamic range without having to use increase the natural chemical concentration

Based on many years of experience of using radioactive tracers at Äspö, there are now written instructions about how to handle experiments with radioactivity. In addition there is a well equipped radiochemical laboratory belonging to Äspö HRL, situated within the CLAB facility. Work with radioactivity in Äspö HRL is regulated by a license from the Swedish Radiation Safety Authority (SSM).

A novel method to clean contaminated water

Hans W Giertz, GiertzTech

This method makes it possible to destroy the solvation shells of chemical elements dissolved in water, causing them to sediment. Hence, it is possible to remove e.g. heavy metals from water. It is also possible to destroy molecules dissolved in water, thereby converting them into their chemical elements. Hence, it is possible to remove e.g. PCB and dioxins from water. As an example the method has been tested since March 2012 in sewage treatment in a small town (6000 inhabitants) and where PO4 was reduced by 85 % in the recipient. The method is currently evaluated in sewage treatment in three towns (60 000, 40 000 and 3000 inhabitants) and where the object is to reduce NH4 and PO4 by more than 99 %. The method builds on a scientific discovery that solves many outstanding issues concerning the atom and configurations of atoms, i.e. molecules. Up to now it has been assumed that static coulomb forces binds atoms to form molecules or binds H2O to atoms forming solvation shells. The method builds on the discovery that a singularity in universe radiates vast amount of low frequency energy and which is absorbed by atoms. Consequently, the atom is not static; however, a dynamic electromagnetic process and the molecule is the sum of its atom’s electromagnetic process. The method is to disturb this process by injecting electromagnetic energy at the chemical element or molecule specific frequency. Two scientific papers describing the theory are available and a third is in press. The presentation will cover theory, method, results from ongoing evaluations and a proposal how the method can be used in Oskarshamn to remove e.g. heavy metals, PCB and dioxins.

Quantification and mapping of pollutant transport in a catchment

Mattias Rönnbäck, Luleå University of Technology; Geosigma

The aim with this study is to develop and test the applicability of methods to quantify and map solute advective travel times and pollutant transport at the catchment scale. Such quantification and mapping can increase the understanding of catchment-scale pollutant transport in general and contribute to the identification of the main sources of water pollution and the most efficient measures to reduce such pollution. The study area is the catchment of Oxundaån, about 20 km north of Stockholm. Water sampling at various locations have shown high PFOS concentrations in surface water and groundwater, but the origin the pollution is unknown. There are also a large number of private sewers in the area, which are of interest with respect to nutrient loads to surface water bodies within the catchment and to Lake Mälaren, located downstream. For detailed GIS modeling of water flow and catchment-scale contaminant transport in water, we use new high-resolution elevation maps, land cover maps and soil maps combined with other available relevant data.

Investigating the role of catchment wetlands in reducing nutrient loads to the Baltic Sea

Andrew Quin, Stockholm University

The Baltic Sea is heavily impacted by eutrophication due to excessive nitrogen and phosphorus loading from anthropogenic sources. To mitigate impacts from point and diffuse sources, the protection, restoration and creation of wetlands has been proposed as a solution. A number of studies have assessed the role of wetlands in retaining nutrients on local catchment scales, often focussing on the effectiveness of single wetlands. However, the effectiveness of multiple wetlands distributed throughout multiple catchments could also be investigated. This study tackles this question by compiling data on nutrient retention (PLC5 data) with data on wetlands (SMD; Eng: Swedish Land Cover Data). This study has been carried out for the South Baltic River Basin District. Better understanding of the nutrient-retention effectiveness of particular types of features distributed throughout multiple catchments, such as wetlands in this study, could help inform water management decision-making aimed at reducing nutrient loads to the Baltic Sea.

Estimating nutrient export and export concentrations at catchment and regional scales using common geographic descriptors

John Juston, Stockholm University

Quantifying nutrient loads to estuaries and other marine bodies is a key to linking upstream activities to downstream eutrophication impacts.  However, discharge from most river basins and coastal regions (worldwide) are not monitored adequately to support direct data-based load computations.  Therefore, there is a continued need to develop, refine and simplify modeling approaches to estimate average nutrient discharge concentrations at catchment and regional scales.  The research herein explores the utility of several relatively simple single and multivariate empirical models for expedient estimation of annual-scale discharge nitrogen (N) and phosphorus (P) concentrations in absence of direct measurements.  Investigations focused on model formulations that used common geographic descriptors, such as population density and percent arable land cover, as independent variables.  Model calibrations were based on data from 114 Swedish river basins that were extracted from a unique national-scale database accounting for nutrient loads to the Baltic Sea.  These data represented a wide range of physical and water quality conditions (e.g., size:  165-50000 km2; arable land coverage: 1-95%; population density: 1-1070 people/km2; annual flow-weighted mean discharge N: 0.2-7.7 mg/L; discharge P: 0.01-0.13 mg/L).  Calibration results were generally very good with some models demonstrating very high correlation to the 114-basin dataset (R2>0.95) accompanied with relatively low standard errors (e.g., RMSE<0.25 mg/L for modeled N across all basins).  Additionally, the model was tested against independent data at various scales from the Baltic region and several basins in the continental U.S. with promising results.  Overall, results indicated an expedient method to estimate past, present and/or future nutrient export concentrations over a wide range of conditions.   This research has global relevance, and with use of fine-resolved data like that expected from NGL development, the approach applicability and possible generality of results can be tested in a well characterized region.

Study of flow and transport of gases, CO2, NAPL and nano-particles in fracture systems on the local and multiple-fracture scales

Auli Niemi, UU – presentation

We propose a project at NGL to the study of flow and transport of gases, CO2, NAPL and nano-particles in fracture systems on the local and multiple-fracture scales. At the local scale, we shall consider issues related to variable-aperture single fractures, complex fractures (with internal structures), and fracture zones. At the multiple-fracture scale level, we shall investigate processes in fracture intersections, sparse fracture networks; and dense fracture networks. The focus of our study will be on the flow and transport of:

• Gases (inert with low solubility; relative permeability effects, etc),
• CO2 (with the added effects of phase change, solubility, dense brine with dissolved CO2, possible presence of mixture gases, etc.),
• NAPL (with the added effects of fluid immobilization and entrapment, interface characterization, interphace mass transfer, etc.),
• Nano-particles (with pore-scale effects, effect of roughness of fracture surfaces, mixing of solutes, colloids, effect of unsaturated fractures (can be coupled with gas injection), etc.

These studies will take advantage of the NGL surface and subsurface facilities. For the local scale; the facility provides a selection of different types of fractures, complex fractures, and fracture zones in the Äspö tunnel. For multiple fracture scale, different types of fracture intersections, sparse fracture networks and dense fracture networks can also be found in the Äspö tunnel. The tunnel also allows the study at depths ranging from close to surface to 460-m depth, and we can define the scale of our study domain ranging from 0.1-m up to ~50-m scale

A probabilistic view of risks associated with consumption of drinking water in an area with natural fluoride enrichments – Kalmar County

Anna Augustsson, Linneaus University

Harmful concentrations of chemicals in groundwater are not always due to anthropogenic pollution, but can sometimes be a result of the local geology. Fluorine is generally found only in trace amounts, but in some areas – around Oskarshamn in Kalmar county, for example- high concentrations are frequently observed in the bedrock and groundwater. Consumtion of drinking water is usually the major exposure pathway for fluorine, and because of the negative effects that occur at high exposure levels, the World Health Organization considers it to be one of the natural elements of greatest health concern. To estimate the likelihood of a certain negative effect to occur, for example the probability of exceeding a certain exposure level in a certain area, environmental risk assessments can be made. However, these are often made using point estimates and generalized assumptions, hence not accounting for parameter variability. In the present study, a probabilistic approach was used to assess fluoride exposure to 4-year-olds in households with private wells in Kalmar County. The results show that a large proportion of the children are likely exposed to fluoride above toxicological reference values after consumtion of drinking water in this region. When considering also other exposure pathways, the proportion of children at risk increases to a majority.

Coastal transport processes: From catchments to archipelagos

Vladimir Cvetkovic, KTH

Understanding the hydrodynamics of archipelagos in the Baltic Sea is increasingly important for short and long term sustainable management of marine resources. Yet, there are still many open questions on water flow and water quality dynamics downscaled to local archipelago regions, not the least understanding the coupled influences from land and sea. The archipelago region of the Äspö island has complex hydrodynamics subject to forcing from the surrounding Baltic Sea on the one side, and impacts from the land freshwater discharge on the other side. The marine environment of the Äspö archipelago will be influenced by both, and distinguishing these impacts is proposed as a NGL research topic. The surface and subsurface hydrological transport pathways from land to the Äspö coastal area, need to be identified using environmental and artificial tracers, combined with hydrological modeling. The forcing from the open sea must account for short and long range impacts, from the islands of Gotland and Öland, to the Gulfs of Bothnia and Finland, to the North Atlantic impacts through Kattegat. An example  study is  presented, using a  three-dimensional flow and transport model. The boundary conditions were derived from the large-scale hydrodynamic model for the Baltic Sea that was fully calibrated for the year 2000 and validated for a 9-year period 2001-2009. The Baltic Sea model accounted for all the major 55 rivers on a daily basis, as well using gridded meteorological forcing conditions. The features studied were wave formation, thermal and salinity stratification, exchange processes and water age. Extensive particle tracking was done to estimate the arrival and transport times of passive tracers released from different locations. A simple ice-model was also used to simulate the formation of ice during winter and early spring periods.

 

Water and climate

Soil moisture dynamics linked with climatic change

Lucile Verrot, Stockholm University

From the Brook and Corey equation established in 1964, describing the relationship between the hydraulic conductivity and the soil water content, it is possible to link the dynamics of soil moisture with the three main components of the water balance in a catchment: Precipitation, Runoff and Evapotranspiration. Analysis of long-term monthly data for those parameters along with soil hydraulic records for different soil types under different site conditions allow us to represent soil moisture variability and change under climate change conditions. This is here exemplified for the Norrstrom drainage basin and for observed climate change there during the last decades. The NGL site with its well-investigated surroundings provide at least as good possibilities for similar studies of soil moisture dynamics, leading to evaluation of possible future changes to soil moisture for various climate and/or land-use change conditions.

Climatological and hydrological response to projected greenhouse gases forcing during 21st century

Peter Rogberg, Stockholm University

Employing results from the latest generation of  Earth System Models (CMIP5) we examine the impact on the Swedish environment over the next century, in particular with respect to the hydrological cycle on national and regional scales. Changes in temperature, precipitation, evaporation and runoff due to different Representative Concentration Pathways are shown. Shortcomings in the models ability to produce consistent water balance projections are addressed. The effects of underlying uncertainties in process understanding and future emissions causes a divergence in predictions. However, model evaluation using observations suggests that identifying a single model that overall performs better is difficult and that another route based on a statistical methodology might be a better way forward. Hydroclimatic field observation data, which is expected to become available through NGL, is needed and important for such climate model reality checks, and for the process understanding developments needed to improve climate modeling and interpretation.

Coupling Climate Change and Anthropic Land and Water Use Change to understand Global Change

Fernando Jaramillo, Stockholm University

Hydroclimatic change manifests in different ways depending on the variable under study and the scale of the analysis. As opposed to temperature, which exhibits a relatively clear global increase during the twentieth century, hydroclimatic variables such as evapotranspiration and runoff exhibit large and irregular heterogeneity, with changes in different directions across different scales. Local-regional drivers, such as anthropic Land and Water Use Change (LWUC), are the most likely causes of such heterogeneous change. In this context, our study of the Motala Ström Basin within the Swedish Southern Baltic Proper Water Management District is of particular NGL-relevance. Such detailed local studies can explicitly distinguish LWUC drivers of hydroclimatic change. This understanding provides a basis for further catchment-wise assessment of hydroclimatic changes and their possible drivers on the global scale, as presented in the present paper.

Climate driven changes – modeling and model testing based on a data-driven degree day approach

Carmen Prieto, Stockholm University

We present a methodology for predicting phenological data, in particular first flight dates of orange tip butterflies (Anthocharis cardamines), as a function of degree day changes under climate change. The modelling approach is based on phenological data available from different regions in Sweden, and spatially interpolated observation data for daily maximum and minimum air temperature in the same regions. The developed degree day model was tested against the observed historical phenological changes and temperature changes between two time periods in the different Swedish regions. By use of more fine-resolved climatic data, like that expected to become available through the NGL development, such modelling approaches to assessing biological/ecological and/or hydrological (e.g., evapotranspiration) effects of climate and climate change can be further developed and tested.

Regional hydro-climatic change − historical assessment and projection

Shilpa Muliyil Asokan, Stockholm University

Hydro-climatic change analysis when carried out at catchment scale provides water balance closure based on the topographically defined catchment boundaries. We have modeled basin hydrological responses to historical and projected future climate, land and water-use changes in case study regions of India and Central Asia. Temperature and precipitation observation data records, as well as projected changes by climate models are then used together with region-specific data on hydrology, water-use and land-use to understand hydro-climatic changes, their drivers, and the reliability of climate model results.

Cross-regional comparison results show that one cannot simply assume similar direction/severity of impacts on water condition changes (wetter/drier) in the landscape only from the assessments/scenarios of climatic changes (e.g., in T, P) as given by the climate models. A comparison of temperature and precipitation outputs of climate models used in the fourth assessment report (AR4) and the latest climate model projections contributing to the assessment report five (AR5) against hydrologically important, basin-scale observational temperature and precipitation dataset show lack of consistency in individual GCM performance with regard to temperature and to precipitation, implying difficulties to identify well-performing GCMs with regard to both of these variables in a region.

Based on even better available, and better resolved regional data, such as can be expected from NGL development, similar approaches can be further applied and tested, for instance for the Swedish Southern Baltic Water Management District, in which NGL is an integral part. A main aim of such regional studies and cross-regional comparisons are to distinguish specific and general hydro-climatic change responses to different climate change scenarios.

Evaluating seawater intrusion at the regional-scale in intensely exploited coastal aquifers with an analytical generalised sharp-interface model

Katerina Mazi, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Greece; Navarino Environmental Observatory, Greece; Stockholm University – presentation

Antonis D. Koussis, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Greece

Georgia Destouni, Stockholm University

Along densely populated coasts, especially in semiarid/arid regions, but also in more humid areas with intensive economic activities, several aquifers are already suffering sea-water intrusion. This phenomenon can accelarate in the future under increased groundwater abstractions, along with climate-driven sea-level rise and possible decline of the aquifer recharge. We use the analytical generalised sharp-interface model of Koussis et al. (2012) to investigate regional-scale, sea intrusion status and perspectives in three Mediterranean aquifers: (a) The Nile Delta Aquifer, (b) the Israeli Coastal Aquifer, and (c) the Akrotiri aquifer, Cyprus, that are facing seawater intrusion due to overexploitation in the past decades. We also exemplify the use of the methodology and the model under the lower than ocean-average salinity conditions in SBD.

In all cases, monitoring the activities in the study area and the natural parameters are essential in setting up a credible model and in achieving a realistic view of the prevailing aquifer conditions.

Prediction of sea-intrusion in unconfined coastal aquifers with 1-D sharp interface models corrected for 2-D submarine outflow dynamics

Antonis D. Koussis, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Greece

Katerina Mazi, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Greece; Navarino Environmental Observatory, Greece; Stockholm University

Fabien Riou, Institut National Polytechnique – ENSEEIHT, Toulouse, France

Georgia Destouni, Stockholm University

Sharp-interface unconfined-flow models with Dupuit approximation overestimate seawater intrusion, mainly due to the shape of their freshwater lens at the coastline that tapers to a knife’s edge, instead to a gap for groundwater discharge to the sea. The zero-area exit is a consequence of the hydrostatic assumption, and of the resulting quasi-uniform flow that ignores the vertical flow in the near-shore region. By ignoring the outflow gap, the interface of Dupuit models outcrops above the point on the interface of 2D models at that longitudinal co-ordinate (x = 0); the same holds for corresponding interface points at all x-values. The interface of Dupuit-type models is thus shallower and penetrates farther inland. However, this hydrodynamic defect can be corrected, without negating the convenient depth-integrated form of Dupuit-type sharp-interface sea-intrusion solutions in phreatic aquifers. One adopts, in Dupuit-interface-flow solutions for finite-depth aquifers, analytical estimates of the outflow gap from potential-flow sharp-interface solutions for infinitely thick aquifers and adjusts the depth at the sea-boundary accordingly. Applications to Mediterranean regional aquifers (Akrotiri aquifer, Cyprus, Israel-Palestine Coastal aquifer and Nile Delta aquifer) demonstrate improved predictive accuracy (using variable-density flow and transport solutions as standard).

Sustainable water supply in coastal hard rock areas – possibilities and challenges

Bosse Olofsson, KTH – presentation

Understanding groundwater storage and flow processes in hard crystalline rock is a prerequisite for assessment of possibilities for sustainable extraction of freshwater along the Swedish coasts and, hence, for development of many coastal areas which mainly consist of bare rock outcrop and limited soil cover. Data from NGL, includng SICADA database can be used for development of methods for calculation of groundwater recharge and groundwater storage in crystalline rock. The presentation gives a review of the present scientific knowledge, possibilities and challenges, e.g. related to water quantity and quality.

Challenges and Opportunities for Interdisciplinary Water-Related Research Consortia

Wendy Graham, University of Florida, USA – presentation

The University of Florida (UF) Water Institute coordinates interdisciplinary research, education and outreach programs designed to develop and share new knowledge, and to develop and encourage the implementation of new technology and policy solutions for water issues.  These programs cultivate partnerships between and among Water Institute faculty, students and external stakeholders; identify and prioritize critical water issues requiring interdisciplinary expertise; and provide expertise and support for addressing these issues. The Water Institute staff facilitates interactions among interdisciplinary teams; decreases transaction costs associated with interdisciplinary proposal writing and project execution; plans and executes Water Institute meetings, workshops, seminars, and symposia; and maintains a comprehensive Water Institute website (http://waterinstitute.ufl.edu) with a searchable faculty expertise, awards, and publication database.

Since its inception in 2006, the Water Institute has brought together interdisciplinary faculty and graduate student teams to develop proposals to external agencies worth over $90 million.  These efforts have created new collaborative linkages among UF faculty, as well as agencies and institutions across the country and have resulted in Water Institute Coordinated Projects totaling more than $10 million. This presentation will highlight some of the challenges and opportunities we have encountered in establishing the UF Water Institute, as well as the goals, activities, and outcomes of a few key interdisciplinary research projects.

 

Rock environment-material characterization and interactions

Cerium sequestration and accumulation in fractures in the upper kilometer of granitoids, Laxemar-Simpevarp area, SE, Sweden

Changxun Yu, Linneaus University

The fracture coatings gathered from the upper kilometre of granitoids in Laxemar-Simpevarp area are characterized by high levels of Ce compared to average wall rock (86 ppm, n=65) and distinct positive Ce anomalies (1.21-3.95, n=8) in the uppermost 20m of the bedrock. Cerium and Mn X-ray absorption spectroscopy of selected fracture coatings, together with existing fracture mineralogy and groundwater chemistry data, indicate that: 1) Ce4+ occurs down to 70 m depth and is exclusively associated with Mn oxides which occur as todorokite and triclinic birnessite probably resulted from oxidative weathering of wall rock and fracture coatings when oxygenated waters intruded into the bedrock during deglacation events (>13000 BP); 2) Ce3+ (also other REE3+) was absorbed by clay minerals as inner-sphere and out-sphere complexes; 3) A dynamic process involving oxidation-reduction cycles of Mn oxides during which Ce4+-enriched residue largely remained was observed in one sample with strikingly positive Ce anomaly (3.95).

Specific surface area and porosity of rock samples from Äspö -work done within the EU CROCK project

Stellan Holgersson, Chalmers – presentation

Drill cores from the Äspö Laboratory have been obtained and characterized with a gas adsorption instrument for specific surface area (SSA), using Kr gas and interpreted with the Brunauer-Emmet-Teller (BET) model. The porosity was measured with two methods: the dry/wet weighing method and the tritium through diffusion method. In addition, the apparent density of the samples was also measured to give the specific pore volume (SPV) of the samples. Some of the samples were then crushed and sieved into four fractions: 1-0.5mm, 0.5-0.25mm, 0.25-0.125mm and 0.125-0.063mm. These samples were also characterized for SSA with BET and also for SPV, using N2 gas and interpreted with the Barrett-Joyner-Halenda (BJH) model. The results for crushed material particle fractions were modeled with an interdependency of SSA on SPV, by assuming a disturbed zone present in the particles of the crushed material, which surrounds an intact core. It is suggested that the origin of the disturbed zone can be the mechanical treatment of the rock or inherited porosity zones in the rock, or a combination of both. However, when extrapolating this model to the BET surface area for intact discs of material, this shows that the measured porosity of the intact material is much larger than what is predicted for the relatively small SSA. This is interpreted as the presence of a macroporosity in the intact material, which contributes very much to the porosity (or SPV) of the intact samples but, on the other hand, contributes very little to the SSA. Instead, the SSA of the intact material is probably dominated by the mesoporosity, which was also measured in the crushed material. Any macroporosity is not measurable in crushed material, either because the macropores (=microfractures) are too large for the gas to condensate in them, or simply because the crushing treatment removes this type of porosity from the samples.

The research leading to these results has received funding from the European Union’s European Atomic Energy Community’s (Euratom) Seventh Framework Programme FP7/2007-2011 under grant agreement n° 269658 (CROCK project) and SKB, the Swedish Nuclear Fuel and Waste Management Company.

Oxygen Effect on Corrosion Resistance of Reinforcement Steel in Simulated Concrete Pore Solution

Fan Zhang, KTH

The reinforcement steel is used in majority of reinforced concreted infrastructures such as buildings and bridges. Many reinforced concrete structures have given excellent service with minimal maintenance. However, as the infrastructure is aged in a corrosive environment, construction and design problems have led to an early deterioration of concrete structures, reducing their residual service life. Corrosion of reinforcement steels is one of the main causes for the deterioration [1, 2].

It is known that the resistance of steels to corrosion is directly influenced by the environment and surface layers. Thus, the study of corrosion behaviour of the carbon steels in concrete must be based on the understanding of the surface conditions of reinforcing bars and environment effect such as corrosion products layer formation promoted by solution dissolved oxygen.

Electrochemical measurements such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization are widely used for studying corrosion behaviour of steels in aqueous environments [3, 4]. EIS is a useful technique for long term tests because it does not significantly disturb the system and it is possible to follow the changes in the interfacial properties over time [5].

In this work, the influence of solution dissolved oxygen on the passivity and corrosion behaviour of reinforcement steel was investigated in simulated concrete pore solutions (SCPS) by a combination of EIS. The results demonstrate the corrosion resistance of the reinforcement increases with exposure time and it is enhanced significantly with the existence of oxygen in the SCPS solution. The increase and enhancement of the corrosion resistance are mainly due to the formation of iron-oxides layers on the steel surface.

[1] J.P. Broomfield, D.B. Kevin, K. Hladky, The use of permanent corrosion monitoring in new and existing reinforced concrete structures, Cement & Concrete Composites, 24 (2002) 27-34.

[2] J. Rodriguez, L.M. Ortega, J. Casal, Load carrying capacity of concrete structures with corroded reinforcement, Construction and Building Materials, 11 (1997) 239-248.

[3] X.M. Liu, Z.M. Shi, H.C. Lin, G.L. Song, C.N. Cao, A Study on Corrosion Behavior of Reinforced Rebar in Simulated Pore Solution by Electrochemical Impedance Spectroscopy, Journal of Chinese Society for Corrosion and Protection, 17 (1997) 19-24.

[4] J.M. Zhao, Y. Zuo, Corrosion behaviour in simulated solutions within pits and crevices on carbon steel, Corrosion Engineering Science and Technology, 42 (2007) 203-206.

[5] S.T. Keera, M.A. Deyab, Effect of some organic surfactants on the electrochemical behaviour of carbon steel in formation water, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 266 (2005) 129-140.

Estimation of characteristic relations for unsaturated flow through rock fractures

Jerker Jarsjö, Stockholm University – presentation

The prevalence of unsaturated conditions in porous and fractured media generally has a considerable influence on flow and thereby also on transport. Characteristic relations for unsaturated flow that are needed in predictive modeling are however difficult to quantify for fractured media, not least due to experimental difficulties. We show how experiments from underground facilities like the Äspö Hard Rock Laboratory can be used to advance the understanding of basic unsaturated flow characteristics, and how results can be processed to meet required input data needs of many of the already existing predictive models for unsaturated flow.

Spent fuel secondary phase characterization under storage conditions

Joaquin Cobos Sabate, Ciemat, Spain

The formation of spent fuel secondary phases under final storage conditions is been identified. It is well known the secondary phases of spent fuel are form mainly by uranyl peroxides. The formation of these phases is associated to the very strong oxidative species produced in the surrounding of the fuel surface, due to water radiolysis present in the final disposal.

The aim of the work is study uranyl peroxides to predict the spent fuel secondary phase formation under repository conditions. Corrosion experiments based on leaching tests in three aqueous media were performed to study the stability of the studtite as a secondary phase formation under geologic final disposal conditions.

The peroxide phases were characterized before and after the leaching tests and the characterization by XRD, SEM and Raman spectroscopy was performed.

Stress induced spalling in hard rock

Lars Jacobsson, SP Technical Research Institute of Sweden

Spalling in brittle rock is seen to occur when the tangential stress around a circular opening exceeds a certain value depending on parameters such as geometry and rock type. Laboratory experiments were carried out on Äspö diorite where a tangential stress was created around a concave surface with the aim to reflect the conditions at a circular opening. The specimens were loaded to a level where extensive fracturing was recorded by means of acoustic emission monitoring. Slabs were cut out from the specimens and impregnated using a fluorescent material in order to more easily visualize the fractures. The fractures were subsequently examined by the naked eye and by means of microscopy images at from which fracture paths could be identified and related to different minerals. The interplay between stress field and microstructure was seen at early stages of spalling which is important for the understanding of the spalling process.

Kinematic Porosity and Heteroscedasticity in Hard Rock Terrains

Robert Earon, KTH – presentation

Hydrogeology in crystalline bedrock, coastal aquifers is problematic due to the heterogeneity and anisotropy in the fracture network. Kinematic porosity of the host rock is exceedingly important for assessing sustainably extractable water supply volumes and assessing contaminant transport within the matrix. This study focuses on the estimation of kinematic porosity from superficial fracture measurements, based on the geometrical properties of the fractures including: fracture frequency, aperture and orientation. The estimates were adjusted for aperture changes with depth and stress, connectivity of the fracture network, fracture closure and measurement orientation bias. The results were compared with well archive data and correlations were significant with more than 95% confidence. Fracture heterogeneity within the bedrock was examined using spatial statistics. Results indicate that heterogeneity is sufficiently high that spatial correlations cease to exist in nearly all investigated rocks at distances greater than 500 m, and in some rocks no spatial correlations were observed.

Coupled processes in subsurface geological systems

Andrew Frampton, Stockholm University

Understanding and being able to predict effects of coupled processes in subsurface geological systems is important for several geoscience applications. However, conceptual, mathematical and numerical modeling of such systems is challenged by difficulties in characterizing and measuring relevant variables and field parameters. Also, several physical constitutive relationships are required to relate primary variables used in mathematical descriptions with secondary variables, i.e. actual field-obtainable, measurable quantities. These are typically based on assumptions inferred from laboratory tests under restricted conditions, or using limited field data sets, and hence consolidation of such necessary assumptions under in-situ conditions is of significant importance for improving the reliability of models and associated quantifications and predictions. The NGL therefore provides unique opportunities to address both of these issues, where subsurface measurements and suitable in-situ tests can be performed.

Multiphase flow interactions in subsurface fracture systems

Benoît Dessirier, Stockholm University

Understanding effects of multiphase flow in subsurface fractured media is important for many applications, such as tunnel construction, aquifer remediation, water abstraction and geological waste disposal. Coupled thermal, hydrological and mechanical processes can occur both in the fracture opening and in the adjacent rock matrix, where air pockets can appear by water degassing or disappear by air dissolution, and the degree of air saturation can significantly alter the flow properties in the heterogeneous bedrock structure. Coupled process-based models can be used to advance the understanding and explore the relative importance of simplifying assumptions and representations of the systems; however models need to be evaluated and tested against real-world measurables. For this, the NGL and its subsurface facilities such as the current Äspö Hard Rock Laboratory can provide the required unique conditions necessary for in-situ subsurface experiments in further advancing the understanding of multiphase flow interactions in subsurface fracture systems.

 

NGL accessibility and educational opportunities

Access to the largest geosphere laboratory in the world – the Äspö Hard Rock Laboratory

Marcus Laaksoharju, Nova R&D – presentation

The unique Äspö Hard Rock Laboratory is open for new research outside the field of spent nuclear fuel and trough the NGL initiative.

Nova FoU (Nova R&D; http://www.novaoskarshamn.se) is a joint research and development platform at Nova Centre for University Studies Research and Development in Oskarshamn, Sweden. The platform is cooperation between the Swedish Nuclear Fuel and Waste Management Co (SKB) and the municipality of Oskarshamn. Nova R&D is the organisation facilitating access for external research and development projects to SKB’s facilities in Oskarshamn,. The facilities are: Äspö Hard Rock Laboratory (Äspö HRL, located 450 meters underground), the Bentonite Laboratory, the Canister Laboratory and Site Investigations Oskarshamn.

The task and aim of Nova R&D are:

• Initiate and support new projects which are using the research infrastructure such as NGL and identify spin-off effects from the research projects
• Important platform for geosphere research, environmental research and technical development
• Networks of researchers, universities and research financiers

Research possibilities and education trough Nova R&D:

• Geology, hydrogeology, hydrogeochemistry, biology and ecology
• Interaction surface, bedrock, sea and atmosphere
• Model-, and database development
• Tunnel, borehole tests, technical development !  Material and instrument techniques
• Social science
• Masters education in “Geological Storage” trough cooperation with Linneaus University/KTH and the EU programme PETRUS II, Ph.D. programmes and post-doc.

The present Nova status is that more than 28 projects are on going and engage more than 100 researchers. The total project value is about 5 million €. Major domestic universities and international universities are involved.

Development of a Joint University (Virtual) Institute for Applied Geosciences

Lars O. Ericsson, Chalmers – presentation

NGL represents a comprehensive facility and data base of advanced experimental techniques and modeling methods for the acquisition and synthesis of data from multi- disciplinary studies in the field of geosciences. It was developed to address a long-term problem of national importance and was the result of a multi-million-euros investment in research and development over the last four decades, leading to major advances in applied geosciences. The information and experience will be most valuable for development of an education program at MS or PhD level in applied geosciences with particular emphasis in multiple-disciplinary integration towards solving a problem of major societal concern. Such emphasis is very much lacking in current geoscience education in all the major universities in the world.

The goal of the proposed Joint University Institute is to develop up-to-date courses for the training of geoscientists who will be properly equipped to address important geosciences-related problems facing the society, ranging from underground construction issues, climatic change, CO2 geosequestration, energy development, environmental pollution  to nuclear and toxic chemical waste disposal. The envisioned institute may be a virtual institute, with education conducted at major universities in Sweden with complementary set of courses, and part of these courses will be held at the NGL facility at Oskarshamn to take advantage of its unique laboratories, data base, and availability of in situ surface and subsurface experimental sites. Four types of courses are to be developed:

• Conventional courses, such as geology, geophysics, glaciology, hydrogeology, rock mechanics  and surface hydrology, but with emphasis towards new techniques and data from NGL and towards solving a major, site-specific, long-term problem
• Double-disciplinary courses, such as integration of hydrogeology and geochemistry, integration of rock mechanics and hydrogeology and integration of microbiology and hydrogeochemistry, with emphasis on coupled processes
• System-integrative courses on the development of so-called “Site Descriptive Models”, process models and predictive models (and back-modeling in paleohydrology and paleogeochemistry) and uncertainty analyses
• Courses on communication of geoscientific results with the public and decision makers, including how to formulate the geoscience results in a broader context and proper perspective.

In coordination, the participating universities may develop complementary sets of courses of reasonable duration (two weeks to one school term), so that they can be attended by students from all over Sweden (and abroad). The students are also expected to participate in site and integrative studies at NGL, taking advantage of its data base and unique facilities for laboratory and field investigations.