MAG-NET Project Descriptions

Post-doctoral position: Dr. Eva Moreno (e.moreno@lancaster.ac.uk)
Starting date: October 1, 2000
Place of work: Centre for Environmental Magnetism and Palaeomagnetism (CEMP)
Department of Geography, University Lancaster, UK
Contact: Prof. Barbara Maher (b.maher@lancaster.ac.uk)

Project outline

The research group in Lancaster has three areas of focus: synthesis and measurement of the magnetic properties of magnetic powders; analysis of the magnetic and complementary properties of modern soils with relation to climate and pollution effects; and monitoring and sourcing of pollutants.

Dr Eva Moreno will use a variety of room-temperature and high-temperature procedures to form grain size-controlled, pure powders of magnetite, maghemite and haematite.  The products will be analysed using x ray diffraction and electron microscopy to determine their purity and grain size distributions.  Their magnetic properties will be characterized extensively, using the newly-installed Magnetic Property Measurement System (Quantum Design) to obtain low- and high-temperature hysteresis and remanent properties at applied fields of up to 7 T.  These measurements will provide more and improved data on the magnetic behaviour of magnetic minerals, to assist in ‘calibration’  of magnetic data obtained from natural magnetic mineral mixtures in natural soil and sediment samples.

Post-doctoral position: Dr. Monika Hanesch (hanesch@unileoben.ac.at)
Starting date: November 1, 1999 (two years)
Place of work: Institute of Geophysics, University of Leoben
Leoben, Austria
Contact: Dr. Robert Scholger (scholger@unileoben.ac.at)

Project outline

The identification and tracing of sources of pollution is an important condition to assess their impact. Many emissions contain (ultra)fine iron-rich particles which are highly magnetic. Environmental magnetism - including the measurement and analysis of the magnetic properties of soils - provides powerful tools for resolving these problems in pollution studies. For instance, more than 2000 samples from the soil repository facility at the Styrian Agricultural Laboratory in Graz show that anthropogenic and natural anomalies could be discriminated by comparing top-soil and sub-soil samples from the same site. Magnetic susceptibility was shown to correlate significantly with some heavy metals (As, Cd, Cr, Pb) depending on the specific situation.

The aim of the work is to assess the applicability of environmental magnetic methods to delineate polluted areas. This needs rigorous validation by cross-calibration with other, more conventional, techniques. The research will focus on the development of a new Austrian database, that serves as a European case study to determine the diagnostic value of environmental magnetism for assessing soil pollution. The samples reflect a mixed contribution of natural background levels and anthropogenic pollution from different sources. Background levels vary as a function of the bedrock, while anthropogenic pollution may arise from industry urbanization or agriculture. Low-field magnetic susceptibility will be measured for each sample and correlated to already existing chemical data which will be made available to the project by the Austrian National Soil Protection Programme. 

Two aspects form the key ingredients to be investigated in the frame of MAG-NET at the University of Leoben: 

• Topic 1: for a complete assessment of the true potential of mineral magnetic data as environmental ‘proxy’ parameters, the contaminating magnetic particles should be characterised in detail. This part of the project will be conducted in close collaboration with MAG-NET partners in Liverpool, Madrid and Marseille. 
• Topic 2: more sophisticated statistical techniques should be incorporated in the interpretational scheme. Since multi-parameter data sets will be generated, a logical option is to incorporate multivariate statistical techniques in the interpretational procedure. This work will involve close collaboration with MAG-NET patrners in Utrecht and Zürich.

Postdoctoral position: Dr. Jan Reinders (reinders@liverpool.ac.uk)
Starting date: August 1, 1999 (two years)
Place of work: Environmental Magnetism Laboratory
Department of Geography, University of Liverpool, UK
Contact: Prof. John Dearing (j.dearing@liverpool.ac.uk)

Project outline

The Liverpool group is working on three streams under the broad topic of “recent environmental pollution“. The first involves testing a method of detecting environmentally significant magnetic minerals. This and other magnetic methods are used in two case studies designed to investigate recent environmental pollution on different geographical scales. 

Methodical Approach
One of the shortcomings of the magnetic method is that we are not yet very well able to discriminate superparamagnetic from multidomain contributions especially if we are dealing with samples of either low mass or low concentration of magnetic minerals. We are exploring the application and benefits of a newly proposed method (Worm, Geophys. Res. Letters, 26, 2557-2560, 1999) and looking into the general properties of the isothermal remanence acquisition in low fields (< 40 mT). Both these methods describe the extremely low coercive fraction. They are easily available for any lab as they do not usually need new pieces of equipment, but can be conducted with the available instruments. 

Case Study Approach
A review of published magnetic studies conducted within the broad topic of “atmospheric aerosols/pollution” is used to gain access to the topic and to lay the fundamentals for the application of the magnetic method in the below described case studies.

Birmingham City Case Study 
The completion of a magnetic survey (1 km x 1 km grid) of atmospheric dusts deposited on  tree leaves across the City of Birmingham is one of the main goals of the Liverpool working group. First results have been encouraging in that magnetic properties of leaves show a geographically meaningful pattern that seems to be related to the intensity of combustion processes in a given area. Additionally, it seems to be possible to discriminate two different grain size fractions one of which can again be tied to combustion processes. 
The general topic of magnetic signatures of atmospheric dust will be tackled in close collaboration with the group in Munich.

Wales Top Soil Case Study
The characterisation of environmental pollution using magnetic methods is further tested on a set of samples taken from Welsh topsoils in a 4 x 4 km grid. A large secondary data set exists that encompasses chemical proxies such as pH, Corg  and elemental concentration of heavy metals and proxies for land use. Here we aim to describe environmental pollution on the one hand, but also hope to investigate the influence of various parameters other than bed rock on the magnetic signal and thus to contribute to the isolation of the climatic signal of soils.

The use of advanced statistical techniques to isolate a presumed pollution signal will be tested using this data set in collaboration with the groups in Leoben and Utrecht.

Postdoctoral position: Dr. Gregg McIntosh (gregc@eucmos.sim.ucm.es)
Starting date: July 1999
Place of work: Departamento de Geofísica y Meteorología
Facultad de Ciencias Fisicas, Universidad Complutense, Madrid
Contact: Dr. Marisa Osete (mlosete@eucmax.sim.ucm.es) or Dr. Daniel Rey (danirey@uvigo.es)

Project outline

An understanding of the climatic controls on sedimentary magnetic properties will enable the scientific community to exploit sediments and soils as archives of past climate change. Furthermore, armed with the knowledge of their "natural" magnetic states, it is possible to determine pollution loadings and pathways in sedimentary environments. Along with fellow MAG-NET members, the Madrid group will be addressing these issues in the following studies.

1. Present day soils.
This study will describe the magnetic evolution of present day Spanish soils, from sites following the general climate trend in Spain of colder/wetter conditions in the NW to hotter/dryer conditions in the SE. Soils formed on river terraces and on clay dunes will be investigated, providing information on the influences of climate and parent material on soil properties, adding to the proposed database of European soils. Furthermore, the clay dunes are very similar to the European loess deposits, thus permitting comparison with soil-forming processes on these well-documented sediments. 

2. Terrace soils/palaeosols.
Here, the aim is to construct records of past climate change from river terrace soil sequences and palaeosol sequences. These can then be compared and correlated with results from marine archives. By considering each of the sources, and their combined responses, a better understanding should be gained of the climatic history of the Mediterranean region.

Oriented and unoriented samples will be taken from freshly-prepared exposures and submitted to a wide range of magnetic measurements. This will be augmented by microscope studies and geochemical analyses. By disseminating all of the information the evolution of the magnetic signal, and the interaction between various factors (e.g. soil structure, water/clay content, Eh/pH, parent material) and the magnetic minerals, will be determined.

3. Present-day surficial seabed sediments
This study will evaluate the reliability of magnetic measurements in assessing the marine influence and heavy-metal adsorption capabilities of coastal sediments.  Sites will be sampled from the Atlantic coast of Spain, in several estuarine-like environments subjected to different degrees of anthropogenic influence. Geographycally distributed magnetic properties will be statistically analysed together with other sediment properties such as texture, mineralogy and heavy metal content.

4. Marine cores from the Spanish Atlantic coast and platform.
The geographical approach outlined above will be complemented with vertically distributed data based on marine cores from the same area. Using similar magnetic and sedimentological properties the temporal evolution of the magnetic signal, and sedimentary properties in general, will be studied. Here the focus is on heavy metal availability during early burial and diagenesis. Several processes related to small-scale and local climatic change, affecting estuarine circulation or storm incidence, provide a context within which to investigate the fate of magnetic mineral assemblages with time. This includes possible links with climatic changes that may also be recognised in continental sequences.

Surficial samples will comprise unoriented Shipek and Van-Veen grabers samples, whilst vertical profiles, both oriented and unoriented, will be obtained from gravity, kasten and vibrocores of different lengths and depths. A broad range of magnetic measurements of whole samples will be accompanied by the investigation of magnetic extracts using SEM and BS, along with EDAX and TEM. These results can then be related to the basic sedimentological properties (e.g. grain size, %CaCO3, %MO), textural propertites and geochemical and mineralogical composition, therebye providing a whole-view picture of the evolution of the magnetic signal, geographically and temporally.

Postdoctoral position 1: Finished (9 months)
Date: June, 1999 - March 2000
Postdoctoral position 2: Edurne Martinez (martinez@cerege.fr)
Starting date: April, 2001 (15 months)
Place of work: CEREGE, Aix-en-Provence, France 
Contact: Prof. Pierre Rochette (rochette@cerege.fr) or Dr. David Williamson (davwill@cerege.fr)

Project outline

Magnetic studies of surface materials (soils, dusts, sediments, solid rocks) show a high sensitivity of magnetic mineral assemblages to anthropogenic and/or natural variables. Such sensitivity results from the ability of magnetic methods to identify changes in the concentration, grain size and mineralogy of iron-bearing particles in the environment, as well as from the variable mobility of dissolved and particulate iron.

In this context, further improvements are required concerning: 1) the origin and fate of magnetic mineral assemblages, 2) the sensitivity of such assemblages to environmental and climate change, 3) possible feedback mechanisms between iron cycle and environmental change. We will address these points by focusing on two topics from the MAG-NET coordinated program.

• Topic 1: Sediment magnetic proxies of climate change across the Indian Ocean during Oxygen Isotope Stage 5e, and to compare these records with other terrestrial and marine paleoenvironmental records.
• Topic 2: Contribution to an inventory of magnetic pollution sources in Europe, and to document the fate of magnetic pollutants in soils and surficial sediments from Southern France.

Several rapidly deposited sedimentary cores from the Indian Ocean, from Indonesia to the Mozambique Channel, are available for this study. The regional climate along this zonal transect is controlled by monsoon circulation, which is a major component of global climate and also strongly influences regional climates around the Mediterranean. The carbonate-rich sediments already yielded a variety of non-magnetic data such as detailed oxygen isotope stratigraphies.

Rock-magnetic properties of U-channels will be measured to obtain a first insight in the sediment magnetic changes, which is to be followed by a detailed study on high-resolution sets of discrete samples. Using "routine" magnetic measurements (magnetic susceptibility, artificially imparted remanences), "pilot" magnetic experiments (high-field measurements, thermomagnetic experiments, magnetic extraction), and other sedimentological/geochemical analyses, we will improve our knowledge of the relationship between magnetic properties and other environmental proxies of primary production, terrigenous sources, and/or early diagenesis. We expect the environmental records as provided by the magnetic study to document  10² to 10³ yr changes in monsoon circulation, a characteristic feature of the Holocene climate. It will then be possible to compare the magnetic signatures of the Stage 5e marine sediments with other terrestrial (lacustrine and loess) or marine environmental records of climate variability.

Topic 2 (Edurne Martinez)
This topic concerns magnetic properties of soils, pollution and weathering processes, in which the candidate will work on either of three projects:

1. Relationship between magnetic minerals and heavy metals in polluted soils;
2. Experimental weathering of magnetic phases in Martian conditions (to model the  high magnetization found in Martian surfaces);
3. Mapping of soil magnetism: testing the performance of a Cesium vapour magnetometer versus Bartington and other electromagnetic systems, and calibrating field measurements with laboratory measurements.

Post-doctoral position: Dr. Adrian Muxworthy: adrian@geophysik.uni-muenchen.de
Starting date: June 1999 - June 2001 (finished)
Place of work: Institut für Allgemeine und Angewandte Geophysik
Ludwig-Maximilians-Universität München, Germany
Contact: Prof. Nikolai Petersen: petersen@magbakt.geophysik.uni-muenchen.de

Project outline

In recent years there have been renewed interest in the magnetic properties of urban dusts, in particular in the characterisation and understanding of the  magnetic signatures of the various urban pollutants. Most of these previous studies have concentrated on standard
environmental magnetic techniques. 

In an attempt to elucidate the origin and understanding of the magnetic carriers,  we plan a detailed rock magnetic study of dusts collected in and around Munich. The samples will be characterised using a variety of standard rock magnetic and environmental techniques, but they were also examined using other non-standard rock magnetic techniques, in particular  Mossbauer spectroscopy and the less common rotational hysteresis.  The application of Mossbauer spectroscopy is an  especially  powerful technique which has not been utilised in previous magnetic dust studies. The dusts will be collected from a variety of sources to access various common sampling techniques:

• airbourne dust collected using in-home 'dust catchers'.  This method of collection will allow for acquirement of the smallest particles.
• street dust collected from various surfaces.
• lake sediments

Post-doctoral position: Dr. Jaume Dinarès Turell (dinares@marte.ingv.it)
Starting date: June 1, 1999 (two years)
Place of work:Laboratorio di Paleomagnetismo, 
Istituto Nazionale di Geofisica, Roma, Italy
Contact: Dr. Leonardo Sagnotti (sagnotti@marte.ingv.it)

Project outline

Environmental magnetism is still a relatively unexploited field of research in Earth Sciences. Major improvements in this field can be achieved through positive integration of expertise and capabilities between different laboratories and the development of protocols for measurements, analyses and interpretation. The MAG-NET project has the potential to bring this discipline significantly forward and the paleomagnetic group of the ING in Roma participates in this project with the aim to cooperate with the other partners to reach the MAG-NET goals, with particular interest in two topics in which we have already developed some expertise:

• Topic 1: Correlation of marine and terrestrial paleoclimate records
• Topic 2: Modelling of mixtures of magnetic particles

Topic 1
This will involve the study of sedimentary cores from the Mediterranean Sea, available at the British Ocean Sediment Core Repository (see Southampton Project  Outline). Our laboratory is equipped for the measurement of  u-channels (up to 1.5 m long), allowing the continuous detection of rock magnetic parameters in sedimentary sequences. The aim is to identify the magnetic proxies of climatic changes during the Quaternary (and eventually downward back to the early Pliocene) in defined marine sequences, for which other relevant data sets exist (geochemistry, clay mineralogy…). Environmental magnetism of these cores will provide original constraints to determine the alternation of periods of relative aridity and humidity and to correlate the climatic signal from terrestrial and marine sequences in the Mediterranean region. Part of the research will be also devoted to the improvement of the techniques for the management of the large amount of data derived from continuous measurements of several rock magnetic parameters.

Topic 2 
This will include the search for measurements and analytical techniques to be used in modelling complex mixtures of different magnetic minerals. Semi-quantitative estimates of  different contributions to magnetic mineral mixtures can be fundamental to extract a “readable” paleoenvironmental signal from a complex magnetic record.

Post-doctoral position: Dr. Clare Peters (peters@geo.uu.nl)
Starting date: June 15th 2001
Place of work: Paleomagnetic Laboratory ‘Fort Hoofddijk’, 
Faculty of Earth Sciences, Utrecht University, The Netherlands
Contact: Dr. Mark Dekkers (dekkers@geo.uu.nl), Prof. Cor Langereis (langer@geo.uu.nl)

Project outline

The acceptance of environmental magnetism outside its own community critically depends on how well the magnetic proxy parameters are understood and quantified, not only with respect to grain size, but also in terms of concentration. Moreover, the considerable analytical merits of mineral magnetic parameters can only be fully exploited when they are calibrated versus more classical analytical tools (e.g. geochemistry, particle size analysis, sequential leaching techniques).

Quantification of environmental magnetic methods and interpretational procedures is a prominent network goal, to be coordinated by the Utrecht group. The Utrecht MAG-NET project, therefore, follows a two-fold approach to both items mentioned above:

• Topic 1: The design, optimisation and validation of environmental magnetism protocols in close consultance with appropriate network partners. 
• Topic 2: A case study of Eemian climate change as reflected in mineral-magnetic, geochemical and other parameters. 

Topic 1
This part of the project involves making an inventory of existing environmental magnetic methods and procedures, and selecting the most appropriate ones. It is desirable to design and carry out experiments for further optimization. Close interaction with other network partners is foreseen. The aim is to develop procedures – to be published in scientific journals and on the MAG-NET website – which serve as the future reference for environmental magnetic methods.

Topic 2
The Eemian occurs within the last interglacial, in isotope stage 5e or 5.5, and represents the nearest geological equivalent to present-day climate and environment. The project aims to study how the climate change is magnetically reflected along a marine to continental gradient in a geographically restricted – and thus climatically very similar  – area (Netherlands and immediate surroundings). Samples are already partially available, because the Netherlands Geological Survey Eemian Project has cored lacustrine and shallow marine sediments and plans to take additional cores in the North Sea in the near future. The fully continental equivalent is represented by a loess section just across the Belgian/Dutch border, with a remarkabe completeness claimed to be unique in NW Europe. Currently, a detailed archeological (Neanderthaler) excavation is carried out. Preliminary sampling has been done, additional sampling and high-resolution sampling (where needed) will be done by the postdoc.

A considerable high-resolution data base of geochemical, mineralogical and other geological parameters is already available as well and will be completed in the framework of the Netherlands Geological Survey project. Therefore, this large mineral-magnetic and non-magnetic data base constitutes an ideal case study to cross-calibrate environmental magnetism methodology with other, more conventional methods. This will involve extensive use of multivariate statistical methods.

Post-doctoral position: Dr. Juan Larrasoaña (Juan.C.Larrasoana@soc.soton.ac.uk)
Starting date: April 1, 2000 (two years)
Place of work: Palaeomagnetic laboratory, Southampton Oceanography Centre,
School of Ocean and Earth Sciences, University of Southampton, UK
Contact: Dr. Andrew P. Roberts (Andrew.P.Roberts@mail.soc.soton.ac.uk).

Project outline

The impact of climate change is an important issue for society. Characterization of past climatic changes represents a vital aspect of developing an understanding of the climate system. While the palaeoclimate record from marine environments is becoming increasingly better known and better resolved, the impact of climate change on terrestrial environments in Europe and surrounding areas is less well-known. The aims of this project are to conduct detailed environmental magnetic analyses on sediment cores from the Mediterranean Sea. 

The research will focus on cores with good dating control (from d¹⁸O and d¹³C stratigraphy). By using environmental magnetic measurements in conjunction with techniques that enable assessment of sediment sources (e.g., geochemistry, clay mineralogy), it is proposed to develop a framework that will allow discrimination between periods of relative aridity and humidity in the source areas of the sediments. This framework will then be used to attempt land-sea correlations, particularly to improve the chronological control in terrestrial areas (e.g., European loess/palaeosol sequences).

Additional aspects of the work will involve developing our understanding of diagenetic processes and building an improved chronostratigraphic framework for Mediterranean marine sediments. 

Many of the cores for this study are available at the British Ocean Sediment COre Repository (BOSCOR) at the Southampton Oceanography Centre (SOC). In addition, long time-series of high-resolution environmental magnetic data for eastern Mediterranean cores (ODP Leg 160) are available back to the early Pliocene. These data will be included in the project and will provide a broader time perspective for the study.

The work will be conducted in close collaboration with relevant scientists at the SOC and with MAG-NET partners in Rome and Utrecht. Funds are available for travel to other MAG-NET laboratories. It is expected that the results of the work will be published in peer-reviewed scientific journals. All MAG-NET post-docs will have the opportunity of participating in advanced training courses in environmental magnetism and related subjects.

Post-doctoral position: Dr. Jacqueline Hannam (hannam@mag.ig.erdw.ethz.ch)
Starting date: November 15. 1999
Place of work: Rock Magnetism Group
Institut für Geophysik, ETH Zürich, SWITZERLAND
Contact: Prof. Friedrich Heller (frieder@mag.geo.phys.ethz.ch) or Dr. Ann Hirt (ann@mag.ig.erdw.ethz.ch)

Project outline

Magnetic properties of sediments contain not only information about the behaviour of the
Earth's magnetic field in the geological past but record also palaeoclimatic and
palaeoenvironmental change at sea and on land. 

The research group in Zürich will focus on a study of recent soils developed in Europe
under different climatic conditions as joint cooperation with the research groups in Madrid
and East Anglia. In addition, rock magnetic properties of hematite crystals of well-defined
grain size will be closely inspected.