MAG-NET: Network for mineral magnetic studies of environmental problems

• Unité de recherche: PCRD EU
• Numéro de projet: 98.0061
• Titre du projet anglais: MAG-NET: Network for mineral magnetic studies of environmental problems

Mots-clé (Anglais)

Environmental magnetism; climate; pollution

Autre Numéro de projet (Anglais)

EU project number: FMRXCT980247

Programme de recherche (Anglais)

EU-programme: 4. Frame Research Programme - 10.1 Stimulation of training and mobility

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

Coordinator: University of Southampton (UK)

Résumé des résultats (Abstract) (Anglais)

Investigations of climatic signals in soils by magnetic measurements
Pedogenic magnetic enhancement over detrital signals in Chinese loess sections has been used to illustrate gross variation and paleoprecipitation in Quaternary climate on the Chinese Loess Plaetau. The precipitation-susceptibility relationship developed for a Chinese monsoonal system, has not been attempted in European. In an investigation of recent soils (developed since the last glacial) on European loess sites across a climatic gradient, discrepancies in the actual and predicted precipitation-susceptibility relationship was evident using the correlation developed for the Chinese system. Variations in loess source over the large spatial extent of the sites may contribute to this difference. Examining sites in close proximity revealed the importance of local geomorphological situations in differentiating the signal, even though their annual precipitation may be similar.
Magnetic biomonitoring of roadside pollution in Zurich
A large spatial survey of the concentration of magnetic components of dust on roadside leaves was undertaken in Zurich. The most abundant tree species was chosen by consultation with the City Council Horticulture and Gardening department. Sites were selected in order to cover both city centre and suburban areas in Zurich. General spatial trends of concentration dependent magnetic measurements highlighted a two order of magnitude difference between city centre and quiet suburban locations on the surrounding hills of Zurich. Heavy traffic flow in transit areas of the city is likely to explain the high values in these areas. Additional local sources from train and tram activity were also identified. A temporal survey of leaf loading showed an accumulation of the signal even with frequent, heavy summer rainstorms over a four-month period. Further investigations into source signatures and provenance are proposed to aid public policy decisions concerning air pollution reduction measures.
Colour analysis of sediments in relation to goethite and hematite
Neoformation of iron oxides in soils can show a climatic dependence. Magnetite forms in slightly reducing, alkaline conditions produced through a cyclical wetting and drying of the soil, hematite requires a period of soil desiccation, and goethite is produced in wetter, cooler situations. Analysis of the Fe oxide components can therefore provide information about the soil forming conditions particularly controlled by local climatic conditions. The magnetic differentiation of goethite and hematite is possible through the investigation of high coercive phases in the magnetic assemblage. Currently magnetic measurements are only able to identify goethite and hematite semi-quantitatively. However, in order for multi iron oxide assemblages to be used to predict soil climatic conditions, quantification of the different components is required. The concentration of these components in mixed mineral assemblages can be quantified by applying colourimetric and spectroscopic methods thereby measuring the amplitude of spectroscopic peaks at particular wavelengths associated with the different minerals. The quantitative relationship between spectroscopic and magnetic measurements is being worked out at present for a number of European soils which formed in different modern climates from Belgium, Germany, Czechia and Spain and should hopefully provide more detailed Fe oxide-climate response models in soils.
Interlaboratory cross calibration of magnetic measurement instrumentation
All partners of the network are involved in an inter-laboratory calibration exercise. The first results have been obtained on different susceptibility measurement apparatus. It turns out that some equipment is very carefully built and produces well comparable results whereas others are of less good quality.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 98.0061