Biological ice nucleators at tropospheric cloud height

E. Stopelli; F.Conen; C. Alewell; C. Morris

Project funded by the Swiss National Science Foundation (SNF) N° 20021_140228

Duration: September 2012-August 2016

Can biological particles affect precipitations on Earth?

Biological ice nucleators (IN) are the most abundant agents to catalyze ice formation at warm temperatures (> -10 °C). Yet, the relevance of biological ice nucleation for cloud processes, such as initiating precipitation, remains ambiguous. In fact, very little is known about the abundance and the nucleation spectra of biological IN in the atmosphere and specifically at tropospheric cloud altitudes. Combining field sampling at the High Alpine Research Station of Jungfraujoch and laboratory experiments on the behaviour of IN, we are addressing some open questions, in particular:

- What are the abundance and spectra of biological IN at tropospheric cloud altitudes?

- Are there environmental factors correlated to this measured IN activity?

- How can the ice nucleation activity of a sample/substances change over time?


For a detailed description follow this link

Evasion of mercury from boreal peatlands

S. Osterwalder; J. H. Huang; C. Alewell; J. Fritsche; S. Åkerblom; M. Nilsson K. Bishop

Project funded by:

Swiss National Foundation (SNF); Doc.Mobility Grant #P1BSP2_148458

Swedish Research Council; Project Research Grant #2009-15586-68819-37

Duration: April 2012 – May 2016

Emission of mercury from the peat surface to the atmosphere is an important factor in regulating the pool of mercury in peatlands and ultimately the loading of highly toxic methylmercury to surface waters. Our main goal was to describe, for the first time, seasonal patterns and to calculate annual totals of the Hg land-atmosphere flux. To test the hypothesis that Hg evasion plays a significant role in the process of Hg removal, we developed a relaxed eddy accumulation system for long-term and large-scale Hg flux monitoring. Furthermore, we used dynamic flux chambers to study controls on mercury cycling in peatlands as well as in industrially polluted areas in Switzerland

For a detailed description follow this link.

Bioleaching and bioremediation of vanadium in minerals, industrial wastes and soils

(a) Disposal site of mine tailings close to the Panzhihua mining site and (b) mine tailings used throughout this study.

J. H. Huang; Y. Xu (University of Zurich);

Founding: Doctoral Promotion Program of Chinese Government Scholarship for Postgraduates Program
Founding period: October 2011 – September 2015
Collaboration: Prof. Dr H. Brandl, Institute of Evolutionary Biology and Environmental Studies, University of Zurich


Vanadium (V) plays a highly critical role in natural systems due to its potential toxicity to organisms. The pollution of V in the terrestrial environment is mostly due to mining activity and burning of fossil fuels. Today, assessing the impact of V enriched solids on the terrestrial environment is extremely difficult due to the limited knowledge about V biogeochemistry. Panzhihua in Chinese province Sichuang is a region abundant with V enriched ores. Due to mining and refining activities, Panzhihua region has a serious V pollution. Taking advantage of the environmental conditions in Panzhihua, we propose to investigate the V mobility in V enriched minerals, industrial wastes and contaminated soils obtained from Panzhihua with different methods, comprising sequential extraction, X-ray absorption spectroscopy and column leaching experiments. Concerning the important role of microorganisms in the biogeochemical cycles of trace elements, the influence of microbial activities, including Fe and S oxidation, Fe and V reduction, HCN and organic acid production, on V mobility in different solids will be studied in detail. Furthermore, attempts will be made to develop bioleaching/ bioremediation techniques based on the knowledge gained in this project. The thorough understanding of the fate of V in the terrestrial environment is urgently required for risk assessment and the implementation of strategies to cope with V pollution.

Influence of arsenate adsorption and microbe-mineral interaction on microbial arsenate reduction kinetics

J. H. Huang; L. Tian

Funding: SNF
Founding period: September 2012 − August 2014


Arsenic in drinking water and soils poses a serious threat to millions of people worldwide due to its chronic toxicity. The oxidised arsenate (As(V)) is less mobile and toxic than the reduced arsenite (As(III)). The reduction of As(V) to As(III) in most environmental systems is driven by microorganisms, but arsenic sorption at the mineral-water interface may strongly influence the rates of this transformation. Understanding the influence of mineral surfaces on the kinetics of microbial As(V) reduction is thus essential to better assess the arsenic mobility and toxicity in soils, sediments, and natural waters. In this project, incubation experiments will be performed to study the influence of As(V) sorption on Fe and Al (hydr)oxide surfaces on the kinetics of the microbial As(V) reduction. The effects of microbe-mineral surface interaction, microbial activities and competition between As(V) and Fe(III) reduction will be studied in detail. The experiments are carried out with arsenic reducing bacteria to focus on the effect of arsenic sorption on As(V) reduction and with iron and arsenic reducing bacteria to study the competition between As(V) and Fe(III) reduction. The biogeochemical fate of arsenic at the water-solid interface is considered parallel from the aspects of microbial activities, chemical speciation and physiochemical processes. The knowledge generated in this study provides new insight into an important environmental process and is needed for the implementation of powerful strategies to cope with the problem of large-scale arsenic release from sediments into water worldwide.

The bioavailability and bioaccessibility of vanadium in soils

J. H. Huang; L. Tian; L. Lu; L. Huang; K. Yang

Founding: National Natural Science Foundation of China
Founding period: January 2012 to December 2014
Collaboration: Prof. Dr J. Yang, College of Architecture and Environment, Sichuan University, China


We plan to investigate the behavior of V in contaminated and uncontaminated soils and its potential uptake by agricultural plants. First, the mobility and bioavailability of V in soils will be characterised using sequential extraction and column leaching experiments. Next, pot experiments will be performed with agricultural plants e.g. soy bean and cabbage at different levels of soil V concentrations to quantify the translocation of V in soils to different parts of the plants. The changes of soil enzyme activities will be also highlighted. The knowledge on V behavior in the environment generated here is essential for accurate assessment of the threat of V contamination to human and environmental health, as well as for the development of novel technologies for remediation of V contaminated soils.



Böden als Klimaregulatoren

Generell findet ein starker Stoffaustausch zwischen Landoberflächen und der Atmosphäre durch Verdunstung von Wasser, Speicherung von Niederschlag, aber auch durch die Aufnahme oder Abgabe von Spurengasen und Aerosolen statt. Damit haben Böden einen wesentlichen Einfluss auf unser Klima. Mit Messungen in und über der planetaren Grenzschicht (untere ~1000 m der Atmosphäre) quantifizieren wir die Quellstärken von klimarelevanten Spurengasen. Eines unserer Ziele ist die unabhängige Überprüfung internationaler Vereinbarungen in Mitteleuropa.

Erosion modeling

C. Alewell; D. Bänninger; N. Konz Hohwieler; K. Meusburger

For erosion modelling an essential requirement is spatially described hydrology. From literature, it was found that usual algorithms applied for this purpose do not route the water flow correctly between adjacent cells. Thus, the first step to make progress in erosion modelling is to get a spatially explicit hydrological model that calculates the water flow correct. First, we propose to use irregular instead of frequently used regular grids because the complex topography of mountain areas can be described with a smaller number of grid nodes and thus reduces computation time. Second, we developed an algorithm, which is simple in its implementation and efficient in computation (Bänninger, 2007).

From the results of our water routing algorithm we can qualitatively conclude that the water routing over the irregular mesh runs correctly and the velocity of water flow routing is independent of the mesh resolution. Qualitative comparison of these results with the results of frequently used algorithms, for example the D8 algorithm, illustrates the advances in hydrological modelling. To make advances in erosion modelling each process has to be considered in a similar way.

Methodologies to measure and characterise fine sediment input to rivers and their effects on health and reproduction of gravel spawning brown trout

C. Alewell; Y. Schindler


Alpine and sub-alpine rivers are threatened by global climate on one hand and on the other, by land use change which both lead increased erosion and hence sediment supply to rivers. Fine sediments are a neglected threat to our rivers and can determine stream quality to a large extent. Sediments in rivers cause increases in turbidity and sedimentation and can ultimately lead to clogging of the river bed. This, in turn, compromises the ecological integrity of the aquatic environment, and can affect the health, reproduction and development of gravel spawning fish, such as the brown trout (Salmo trutta). This project aims to further our understanding of the complex interactions of sediment input and effects on brown trout by firstly, characterising the sediment load, the relationship between water flow and clogging ,  river bed erosion and  dynamics of sediment input during the year, as well as of the composition and quality of the fine sediment particles. Secondly, methods to study the effects of the sediments in the abiotic aquatic environment, such as river bed clogging, will be developed and optimized. Thirdly, biotic components will be studied by assessing the health, reproduction and development of brown trout in the field and in the laboratory. Special emphasis will be given to the effects of environmentally relevant conditions such as exposure regime and composition of sediments, their particle size and quality of suspended as well as bedload sediments on the biotic components studied. Finally, a model based on the life-cycle of the brown trout will be used to assess the effects of fine sediments on trout recruitment.

To address the corresponding questions, an interdisciplinary research approach is needed. This particular project is consist of the three working groups MGU, Applied and Environmental Geology, and the Environmental Geosiences.

Land use effects on soil hydrology in alpine ecosystems

C. Alewell; M. Müller


This project is part of the interdisciplinary KIP projekt "The ecological and socio-economic consequences of land transformation in alpine regions: an interdisciplinay assessment and valuation of current changes in the Urseren Valley, key region in the Swiss central Alps" (Project leader: Christian Körner, Participants Christine Alewell, Frank Krysiak, Rolf Weingartner, Martin Schaffner).

Over wide parts of the Swiss Alps the main changes in land use are reduced farming activities, which have led to massive shrub encroachment (e.g. green alder) and forest expansion into formerly open habitats. These land use changes affect the hydrology of soils and adjacent lowlands. In our test region, the Ursern Valley in the Swiss Alps, we assess the status and current change of vegetation cover and its influence on soil characteristics, and their combined effects on the soil water balance and soil integrity. The green alder expansion in the Ursern Valley has been considered as one of the largest and fastest across the Swiss Alps.

In several micro catchments with different green alder densities we investigate how the expansion of green alder affects the soil hydrology compared to land use type grassland. Water balance components will probably be affected by green alder shrubs through increased interception, evapotranspiration and infiltration compared to grasslands. Further, green alders can be expected to alter soil physical and chemical properties. Investigated soil hydrological parameters include volumetric soil water content to estimate water infiltration, surface flow and soil erosion, soil bulk density, and water residence times in soils. The latter will be studied by a stable isotope approach. The influence on stream water quality will be evaluated by measuring stream water properties like sediment load (turbidity) and dissolved organic carbon content.

Collaboration agreement (11/2010-5/2011) between the Federal Office for the Environment (FOEN) Switzerland and the Institute for Environment and Sustainability (IES) – Action SOIL, Joint Research Centre (JRC)

C. Alewell; K. Meusburger; L. Montanarella


Since 2005, the Institute of Environmental Geosciences is engaged in the assessment and monitoring of mass movements, sheet erosion and soil erosion risk factors in the Alps. New methods have been developed for mountain regions. The methods applied range from remote sensing, modelling, isotope analysis (C-13, N-15, Cs-137) to field measurements and soil mapping. The objective of this project is a mutual data and knowledge transfer between Switzerland and the EU concerning soil erosion risk assessment.

The project is funded by the Federal Office for the Environment.

Strategic Korean-Swiss Cooperative Program

Gully erosion in the headwater catchment of Lake Soyang (water reservoir).

C. Alewell; J. H. Park


The primary goal of the proposed research is to establish a Korean-Swiss cooperative research network focusing on the biogeochemical study of soil erosion and carbon export in mountainous terrain. Methods and approaches developed on the Swiss and the Korean field sites will be exchanged, evaluated and verified on the partner sites to test for general applicability. The combination of the methods will allow the research group to expand research interests and application. The project also aims at providing baseline scientific information essential in developing a risk management system for landslides and sheet erosion on steep hill slopes in response to climate change.

Soil degradation and nutrient export in the upper alpine level of the Reuss watershed

Fingerprint hypothesis of soil degradation: if soil erosion is influencing area B significantly, stable isotope signature should differ from C.
An example: Laui site with sampled transects.

C. Alewell; M. Schaub Brodbeck


It was the aim of this project to record stable isotope signals of carbon and nitrogen for sites with differences regarding aerobic or anaerobic metabolisms. A second aim was to determine soil degradation by analyzing the deviation of stable isotope signals in erosion source and sink sites in comparison to non-degraded sites. Soil degradation of upland soils, especially export of nutrients, influences significantly nutrient content and biogeochemistry of riparian zones and wetlands in catchments.

Transects in stable isotope dynamics were determined from upland soils (oxic environment and erosion source) to lowlands (predominantly anoxic environments and sink of erosion material). Because oxic upland soils with a predominantly assimilatory metabolism differ significantly from anoxic wetland soils and riparian zones with dissimilatory metabolism, stable isotopes of sulphur, nitrogen and carbon are suitable tracers for the erosion of soil material from upland to lowland soils.

Quantification of Soil Erosion in an Alpine Watershed of Switzerland (Urseren Valley, Canton Uri)

NaI-Spectrometer to measure the activity of radioisotopes.

C. Alewell; N. Konz Hohwieler; V. Prasuhn

The aim of this study was to quantify soil erosion in an Alpine catchment. The WEPP model was modified and validated with field measurements of radionuclides and sediment traps.

Field survey techniques to measure soil erosion in mountainous regions were developed within this project. These measurements included the radioactive isotopes Cesium-137 technique as well as modified sediment traps to be used in alpine regions.

Soil Erosion in the Alps (spatial analysis of causes and risk assessment)

Soil erosion maps derived from aerial photographs are spatially compared to divers thematic maps.

C. Alewell; K. Meusburger

In mountain environments, difficulties in accessibility and data acquisition are paired with a high degree in small-scale heterogeneity. Thus, successful approaches to assess susceptibility to soil erosion at catchment scale (30 km2) are bound to regionalization of data with GIS based modelling and remote sensing using very high resolution satellite imagery (QuickBird).

The aim of this work was to identify causes of soil erosion (sheet erosion and shallow landslides) as well as the mapping of risk areas rather than an exact quantification of sediment rates. The first aim was achieved by field observation and multidimensional spatial evaluation of controlling factors. This required informative data layers such as surface cover, geology, geomorphology, land use, soil and erosion features. Mapping of soil erosion features is done by field mapping, image analysis of aerial photographs and satellite imagery and soil erosion modelling. The aerial photographs are analyzed for different years in order to implicate the progress of soil erosion with climate parameters and land use changes.

The project is funded by the Swiss Federal Office for the Environment (BAFU).