Issue No.01 January 2000

Newsletter of the Environmental Network (MAG-NET) www.geo.uu.nl/~magnet E 2000 29 Apri-1May Cassis UROPEAN N ETWORK FOR

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7. Inter-laboratorycalibration(Dekkers) 6. Loessmagnetism(Heller) 5. Magneticextractiontechniques(Maher) (Petersen/Muxworthy) environmental magnetism Mössbauer 4. spectroscopy:Applicationsin complicated samples?(Pike/Dekkers/Roberts) unravelling thecomponentswithin 3. Hysteresistechniques:Isthereanyhopeof studying pollution(Reinders/LiverpoolGroup) 2. Overviewofmagneticapplicationsto (Roberts) weaknesses magnetisation ofsediments:Strengthsand 1. Theu-channeltechniqueformeasuringthe Possible "keynote"talks: G

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N [email protected] (contributions, suggestionsetc.alwayswelcome) Geofisica, ViadiVignaMurata605, 00143ROMA,E-mail: MAGazine iseditedbyJaumeDinarès-Turell, IstitutoNazionaledi T

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M T M E E AGNETIC S below. group. Apreliminaryprogramisoutlined Cassis andorganizedbythe Aix-Marseille training encounterwillbeheldinthetownof Just aftertheEGSmeetinginNice,aMagnet TUDIES OF E MAGazine No. 01,January2000 NVIRONMENTAL P ROBLEMS

1 THE MAG-NET CONTRIBUTIONS AT THE EGSXXV GENERAL ASSEMBLY (NICE, APRIL 2000) EGS-2000

SE26. Open session on palaeo, rock and environmental magnetism SE3.02 The Earth's core: Palaeointensity: methods, results and possible SOLID EARTH implications for the geodynamo GEOPHYSICS (SE) SE27. Palaomagnetism and supercontinents: taking the pulse of the Earth: Palaeo, Rock and SE1.02 Alpine and Mediterranean region: Palaeomagnetism: tectonics, Environmental Magnetism dating and stratigraphy SE28.01 Materials, methods and applications in : Thermoremanence: 50 years since the first studies of L. Neel SE28.02 Materials, methods and applications in rock magnetism: Magnetism of volcanic materials: from lavas to fly ashes SE28.03 Materials, methods and applications in rock magnetism: Magnetic measurements in oil and mineral exploration SE29.01 Environmental magnetism-signature of past changes and present environment: Magnetic signatures in sedimentary environments SE29.02 Environmental magnetism-signature of past changes and present environment: Soil magnetism, and pollution SE29.03 Environmental magnetism-signature of past changes and present environment: Magnetism in archaeology

CHARACTERIZATION OF SOURCES OF POLLUTION IN AUSTRIAN SOILS BY MEANS OF MULTIVARIATE STATISTICS

M. Hanesch (1), R. Scholger (1), M.J. Dekkers (2) stablishing the amount of contamination of soils in (1) Institute of Geophysics, Eindustrialized countries to assess potential University of Leoben, Austria, (2) environmental hazard is a long lasting problem which Faculty of Earth Sciences, Utrecht attracted growing attention during the last decade. Soils are University, The Netherlands [email protected] known for their filter and buffer capacity. Nonetheless, high concentrations of contaminants may lead to high SE29.02 concentrations in plants, thus potentially hazardous to the biosphere. To avoid threatening contaminations, it is important to map the distribution of pollutants and to trace their sources. A grid (approximately 4 km x 4 km) of sampling points was spanned over the states of Eastern Austria (39527 km2). At each grid point, topsoil and subsoil samples were analysed by pedological and chemical methods. Correlation of chemical data with showed that magnetic susceptibility is a suitable proxy parameter for heavy metal pollution, testifying the usefulness of environmental magnetic methods. Natural and anthropogenic contributions were distinguished by comparing topsoil and subsoil samples. We plan to use multivariate statistical methods to unravel the different factors contributing to the pollution. We aim to identify pollution sources and pathways of the pollutants.

MAGazine No. 01, January 2000 2 EFFECTS OF LONG-TERM FERTILISING TREATMENTS ON THE MAGNETIC PROPERTIES OF TOPSOILS

J.A. Hannam (1,2), J.A. Dearing he unique Broadbalk experiment at Rothamsted U.K. (2), J. Catt (3) Tprovides the opportunity to assess the effects of continuous long-term (>150 years) fertilising treatments on (1) Institute for Geophysics, ETH- the neoformation of ferrimagnetic minerals in topsoils. Over Hönggerberg, 8093-Zürich, 300 topsoil samples were taken from a range of fertilising Switzerland (2) Department of treatments. Spatial distribution of χ , χ and χ Geography, Roxby Building, LF FD ARM indicate higher concentrations of fine and ultra-fine University of Liverpool, Liverpool ferrimagnets on plots receiving high concentrations of L69 3BX, U.K. (3) Department of inorganic-N fertilisers. Remanence parameters (SIRM and Soil Science, IACR-Rothamsted, 1T HIRM0. ) are more variable and do not reflect the marked Harpenden AL5 2JQ, U.K. 3T patterns in the susceptibility parameters related to fertiliser [email protected] concentration or media. Loess redistribution on the site may SE29.02 explain the variability in remanence parameters and differences in comparable field sections. Fertiliser samples show diamagnetic and paramagnetic behaviour and are therefore excluded as a possible ferrimagnetic source in the treated topsoils. Denitrification coupled with Fe transformation path- organic -N No minerals low high medium fertilisers amendment only inorganic-N inorganic-N inorganic-N N ways are proposed as a mechanism for the increased ferri- magnetic signal on 40 the high inorganic-N

35 treated plots. In- creased denitrification 30 activity by bacteria on

25 the heavily fertilised plots may promote 20 the reduction of Fe3+

15 once nitrate con- centrations have been χLF -8 3 -1 depleted. This would 10 m 10 m kg provide a large pool χ Spatial plot of LF from topsoil samples across the field section. The area of Fe2+ and the investigated incorporates field plots (10x30m) receiving various type and potential for trans- concentration of fertilising treatment. formation to mag- netite through hydro- lysis and oxidation in the pedon. Archive soils, collected by Rothamsted at periods over the course of the experiment, were also measured to investigate temporal changes in ferrimagnetic concentration as an attempt to elucidate rates of enhancement. Samples indicate that even 40 years after the onset of the experiment, plots receiving high inorganic-N fertilisers already show greater concentrations of fine and ultra-fine ferrimagnets than those that were unamended or amended with organic-N fertiliser.

MAGazine No. 01, January 2000 3 ROCK-MAGNETIC PARAMETERS OF INDIAN-OCEAN SEDIMENTS IN CORRELATION WITH THE LAST INTERGLACIAL

Y.S. Kok (1), D. Williamson (1), L. he study focuses on sedimentary records of magnetic Beaufort (1), T. de Garidel-Thoron Tparameters of the last interglacial period or oxygen- (1)and F. Guichard (2) isotope stage 5e. Knowledge of the climate vari- ability at (1) CEREGE, Universit_e Aix- submillenial scale during this period is especially relevant Marseille III, F-13545 Aix-en- for under-standing the present-day interglacial. Our material Provence, France, (2) LSCE, F- 91198 Gif-sur-Yvette, France. consists of several Indian-Ocean cores, from the Indonesian [email protected] archipelago via the Maldives to the Mozambique Channel. SE29.01 Their oxygen-isotope stratigraphies indicate ages up to circa 170 ka and cover the interglacial period ¢ 130{100 ka. First, the standard rock-magnetic properties of the U-channels, i.e. magnetic susceptibility and natural remanent magnetization, were mea- sured to obtain an impression of paleoclimatic and -magnetic variability in the cores. For instance, a paleomagnetic anomaly, that we link to the Blake event, is located at the young end of stage 5e. Next, a detailed 0 MD972138 ∆ ARM 1 0 0 study on high-resolution sets of discrete samples of 200 200 magnetic susceptibility, artificially-imparted and natural remanences, and 400 400 thermomagnetic expe- riments was carried out. The relationship between 600 600 magnetic properties and environmental proxies

Depth (cm) suggests links with sea- level variations, and 800 800 possibly additional e_ects originating from primary production or magnetic- 1000 1000 particle sources. 25 50 75 100 -1 -2 -3 AF (mT) ∂ 18 O

Example of a contour plot of deep-sea Indonesian archipelago core indicating differentials of ARM acquisition curves, normalized by maximum differential, in correlation with its oxygen-isotope curve, in which stage 5e can be found at 740-760 cm depth.

MAGazine No. 01, January 2000 4 THE BLAKE GEOMAGNETIC EPISODE IN CORES FROM THE MEDITERRANEAN SEA: EVIDENCE FOR A "DOUBLE" EVENT

J.Dinarès-Turell (1), L. Sagnotti (1) he Blake episode is undoubtedly the best-established and A.P. Roberts (2) geomagnetic feature within the otherwise normal (1) Istituto Nazionale di Geofisica, T polarity Brunhes Chron. The age of the Blake event is Roma ([email protected]/Fax: +39-06-5041181), (2) University of bracketed between 110-120 ka as suggested by oxygen Southampton, Southampton isotope records, by thermoluminescence dating and by Oceanography Centre, UK astronomically-tuned chronologies in several marine, SE26 lacustrine and continental (loess-paleosol) records. The exact location, duration and nature of the episode within the 2.9 loess-paleosol sequences is somewhat controversial. Its stratigraphic position has been reported either below the 3.0 boundary between paleosol S1-c of the last interglacial (equivalent to marine isotope stage 5e and loess L2-2 (5d) 3.1 or in a younger location within the loess unit. In Mediterranean marine records, the Blake event is located 3.2 between sapropels S4 and S5, an interval that represents the 3.3 transition between oxygen isotope sub-stages 5e and 5d, although the event has not been detected in some high- 3.4 resolution records despite unambiguous sapropel stratigraphies and adequate sedimentation rates. 3.5 Depth (cm) We present new results from high-resolution U-channel 3.6 (and discrete sample) measurements from two Mediterranean piston cores which appear to be consistent 3.7 with the established chronologies. The data suggest that the Blake event comprises two fully reversed polarity intervals 3.8 that are separated by a short normal polarity interval (see Figure). However, diagenesis seems to act as a smoothing 3.9 factor in one of the records. 4.0 -90 -45 0 45 90 Inclination

Tephra layer NRM inclination at dif-ferent alternating field de-magnetization steps in core LC10 showing the "double" Blake. The corresponding position in a composite image of the upper part of the core and its relation to 0 mT S6 is given. 20 mT 40 mT 60 mT

Sapropel S6

MAGazine No. 01, January 2000 5 HIGH RESOLUTION GEOMAGNETIC RECORDS FROM PLEISTOCENE MEDITERRANEAN SEDIMENTS: EVALUATING THE CLIMATIC RESPONSE

J.Dinarès-Turell (1), L. Sagnotti (1) and A.P. Roberts (2) igh resolution magnetic measurements on U- channels from Mediterranean piston cores LC07 (1) Istituto Nazionale di Geofisica, H (35° 8.72' N, 10° 4.73 E) and LC10 (35° 12.77 N, 16° 34.88' Roma ([email protected]/Fax: +39-06-5041181), (2) University of E) provide a straightforward magnetic stratigraphy which Southampton, Southampton indicates the record of the upper Jaramillo, the Oceanography Centre, UK Matuyama/Brunhes transition and documents the entire SE29.01 Brunhes Chron in both cores. This basic time framework renders a mean sedimentation rate of ~1.9 and 2.3 cm/kyr in Susceptibility (x10-6 SI) cores LC10 and LC07 respectively. The magnetic signature in the Ionian sea core LC10 is of lower quality owing to the 200 100 0 7 very low coercivity of the remanence carriers although the presence of some sapropel/sapropelitic layers provide additional clues as to the climatic forcing in this core. 9 Available oxygen isotopic data down to stage 7 from the upper part of the west Tyrrhenian LC07 core together with 8 correlation of low field magnetic susceptibility variations to the insolation curve for the last 1.1 Ma provide the necessary time control in this core. Rock magnetic data, directional variations and derived relative palaeointensities 9 using different normalization approaches are evaluated and 11 compared to reference stacks and records elsewhere.

100 6x104 10 400 100 kyr kyr δ18O Bassinot et al. 80 Susceptibility core LC07 M/B only LC07 time model

11 Depth (m) 60 41 kyr

40 23 kyr

12 Power spectrum 19 kyr 20 Power spectrum LC07

0 0 0 0.01 0.02 0.03 0.04 0.05 0.06 13 Frequency (kyr-1) The M/B boundary (known to occur in isotopic stage 19), recorded at 15 about 17.8 m, has been taken as tie point in core LC07 to correlate the susceptibility record to the δ18O record from Bassinot et al. (1994). An age model is constructed by correlating main features in both curves (i.e. 14 glacials preceding stages 9, 11 and 15, figure on the left) The spectral analysis (Blackman-Tukey method) from the whole core indicates a climatic forcing for the susceptibility signal (figure above).

MAGazine No. 01, January 2000 6 MAGNETIC CHARACTERISATION OF URBAN DUST AND POTENTIAL USE OF MAGNETIC MONITERING AS A METHOD OF HEALTH RISK ASSESSMENT

A. R. Muxworthy, N. Petersen, E. n recent years there has been a renewed interest in the Schmidbauer and J. Matzka Imagnetic properties of dusts, and in particular the Institut für Geophysik, Universität potential of using magnetic techniques as a method of München, Munich, Germany health risk assessment. To do this it is necessary to have a SE29.02 good understanding of the magnetic constituents of dust; both of natural and anthropogenic origin. Although previous studies have been revealing + near stoichiometric iron there are still uncertainties as to the maghemite nature and origin of the magnetic signature. In this study, we have 1 conducted a detailed magnetic study of several dust samples collected from 0.995 various localities in and around Munich, and attempted to characterise 0.99 magnetic properties. We have utilized several different approaches; from standard techniques such as magnetic 0.985 hysteresis and SEM analysis to non- Transmission (normalised) standard rock magnetic techniques 0.98 such as Mössbauer spectroscopy and -8-4048 rotational hysteresis. velocity (mm/s) When used with magnetic techniques, Fig. 1. Mössbauer spectrum for DC5 displaying type 1 (see Table 1) behaviour. A fitted spectra is also shown, Mössbauer analysis is a particularly with the particular iron and magnetite?maghemite powerful tool which has not been sub?spectra. The strong doublet in the middle is due to a paramagnetic signal. readily utilized in previous dust magnetic studies. Early Mössbauer results suggest that the magnetic signature is carried by a combination of near-iron and magnetite-like grains (Fig 1 and Table 1). Thermomagnetic analysis also confirms the presence of an iron component rarely seen in dust samples. Qualitative SEM analysis suggests that the magnetic signature is carried by the smallest and most dangerous grain size fraction (< 1.1 µm). Hysteresis measurements find that the ferromagnetic component do not completely saturate in the maximum field

Sample Location Dates (1999) Hc (mT) Hrc (mT) DC1 2 12/9-21/9 8.4 38.8 DC2 1 19/9-5/10 9.1 43.6 DC3 1 19/9-5/10 8.9 42.1 DC4 2 24/9-8/10 8.9 39.1 DC5 1 8/10-21/10 11.8 50.3 DC6 1 21/10-16/11 10.2 47.5

Table 1. Summary and details of the six samples studied, including the location, Mössbauer category (1 = high iron content, 2 = reduced iron content) and coercive force (Hc) and remanent coercive force (Hrc) from the hysteresis measurements.

MAGazine No. 01, January 2000 7 of 230 mT, indicating the presence of 0.6 , iron or some other mineral with a SD high saturating field. The samples have Hc values which suggest grains sizes for magnetite of 0.2-5 µm or for iron of 0.1-0.3 0.4 PSD µm, but the samples have Hrc values which s are normally associated with grains of only M 0.1-1 µm in diameter for magnetite (Table rs/ 1). These values are in agreement with M 0.2 previous studies (Matzka, 1997). The hysteresis parameters are summarized in a Day plot in Fig 2. The samples plot out with the conventional regions as defined by Day MD + SP et al. (1977), but Jackson et al. (1990) have 0 attributed this type of behaviour to bimodal 024coercivity distributions where the higher Hrc/Hc coercivity phase carries most of Mrs. The Fig. 2. Mrs/Ms versus Hrc/Hc (Day plot) for the six dust Mrs/Ms ratio indicates a grain size range samples. assuming magnetite of 0.1-1 µm. The two samples collected later in the year, i.e., DC5 and DC6, have hysteresis properties indicative of slightly smaller grain sizes (Table 1). In an attempt to correlate the dust studies with dust actually trapped within the lung, it is hoped to present preliminary results from dogs' lung tissue which will be compared to the dust measurements.

Day, R., F, M.D. Fuller and V.A. Schmidt, Hysteresis properties of titanomagnetites: Grain size and composition dependence. Phys. Earth Planet. Inter., 13, 260-267, 1977.

Jackson, M., H?U Worm and S.K. Banerjee, Fourier analysis of digital hysteresis date: rock magnetic applications, Phys. Earth Planet. Inter., 65, 78?87, 1990.

Matzka, J., Magnetische, elektronmikroskopische und lichtmikroskopische Untersuchungen an Stäuben und Aschen sowie an einzelen Aschepartikeln. Diploma Thesis. Univ. München, 1997

ROCK MAGNETIC PROPERTIES OF POLLUTION SOURCE MATERIAL

J. Reinders he modelling of environmental magnetic signals to Dept. of Geography, University of Tdecipher the contributions of natural and/or Liverpool, Roxby Building L69 anthropogenic sources crucially depends on our knowledge of 7ZT, UK, [email protected] the ranges that magnetic parameters of source materials can take SE26 Therefore we are working on the characterisation of "pure" anthropogenic materials. Our first goal is the investigation of material that evolves during the combustion of organic materials. SEM-observations of magnetic extracts of source materials additionally support the usefulness of a catalogue of environmentally potent materials. First results of detailed rock magnetic analysis of combustion materials (ashes of various provenances) will be presented.

MAGazine No. 01, January 2000 8 - MEETING/COURSES CALENDAR

29 February GEOLOGICAL EUROPEAN GEOPHYSICAL Sustainable Development: SOCIETY -Environment Group SOCIETY XXV challenges for the Third The role of geosciences in Millennium Conference on Earth, Millennium, Rio de Janeiro, Brazil, environmental assessment and Planetary & Solar Systems Sciences 6-17 August 2000. appraisal At Burlington House, Nice, France, 25 - 29 April 2000 [email protected], London, UK Contact: Dr Brian www.copernicus.org/EGS/egsga/nic www.31igc.org Marker, Tel: 0171 890 3851, e00/nice00.htm. [email protected] JOINT STATISTICAL TRACERS AND MODELLING MEETINGS Celebrate Diversity 10-14 April GEOLOGICAL IN CONTAMINANT HYDROL- in Statistics, Indianapolis, Indiana, SOCIETY-Joint Assocation for OGY, LiŠge, Belgium, 23-25 May 13-17 August 2000. American Quaternary Research Annual 2000. TraM'2000, LGIH, University Statistical Association / Institute of Field Meeting and AGM East of LiŠge, B19 Sart-Tilman, 40000 Mathematical Statistics Anglia, UEA, Norwich LiŠge, Belgium; Phone: +32 4 366 International Biometric Society, www.qra.org.uk, Simon Lewis, 2216; Fax: +32 4 366 2817; ENAR and WNAR Statistical [email protected] or Colin [email protected] Society of Canada. E-mail: Whiteman, [email protected]; phone (703) [email protected] AMERICAN GEOPHYSICAL 684- 1221. UNION (Spring Meeting), 6th International GEOSTATIS- Washing-ton, DC, 30 May - 3 June geoENV2000 3rd European Conf. TICS CONGRESS, Capetown, 2000. AGU Meetings Department, on Geostatistics for Environmental South Africa, 10-14 April 2000. 2000 Florida Avenue, NW, Applications, Avignon, France, 22- The deadline for submission of the Washington, DC 20009 USA ; 24 Nov. 2000. Unite de Biom‚trie, final papers has been extended to Phone: +1 202 462 6900; Fax: +1 INRA, Domaine St. Paul, Site Nov.30, 1999. Lesley Stephenson, 202 328 0566; Agroparc, 84914 Avignon cedex 9, Con-ference Co-ordinator, P O Box [email protected]; France; ph. +33 432 712170, fax: 327, Wits, 2050, South Africa. Tel: www.agu.org +33 432 712182, (0011) 27 11 716 5091; Fax: (0015) [email protected] 27 11 339 7835 E-mail: NEW TRENDS IN www.avignon.inra.fr/biometrie/geo [email protected] GEOMAGNETISM VII, env2000 PALEO, ROCK AND ENVI- Society for SEDIMENTARY RONMENTAL MAGNE-TISM IAMG Annual Meeting, Cancun, GEOLOGY Annual Meeting. New Castle Moravany, Slovakia, June Mexico, 6-12 June 2001. Jorgina Orleans, LA, USA,16-19 April 19-25, 2000 http://gpi.savba.sk Ross, Kansas Geol. Survey, 2000. Judy Tarpley, 918-493-3361 convenor. ex. 22, fax: 918-493-2093, email: 2000 Western Pacific Geophysics www.kgs.ukans.edu/Conferences/I [email protected]. Meeting June 27-30, 2000 Tokyo, AMG/index.html www.sepm.org/research/conference Japan s/sepm_conferences.html "Sedimentary magnetic records of the past climate, geomagnetic field, AMERICAN ASSOCIATION OF and tectonic processes" PETROLEUM GEOLO-GISTS, Abstract DEADLINE March 16, ann. mtg., New Orleans, La., 16-19 2000 April 2000. AAPG, 1444 So. www.agu.org/meetings/wp00top.ht Boulder Ave., P.O. Box 979, Tulsa, ml OK 74101-0979. Phone: 918/560- 2639. Fax: 918/560-2626, 4th International Symposium on [email protected] SPATIAL ACCURACY ASSESS-MENT in Natural 17-20 April EIGG/Environment Resources and Environmental Geoscience 2000 - Contaminated Sciences, Amsterdam, 12-14 July land and the quality of life At 2000. Symposium chair Dr Gerard University of Manchester Contact: B.M. Heuvelink, University of Conference office, Burlington Amsterdam, Nieuwe Prinsengracht House 130, 1018 VZ Amsterdam, The Netherlands. [email protected], 17-20 April Joint Assocation for www.gis.wau.nl/Accuracy2000 Quaternary Research Geoscience 2000 - Shelf sea palaeoceano- GEOFLUIDS-III-2000 graphy: the Quaternary period At Barcelona, Catalunya, 12-14 July University of Manchester Contact: www.ub.es/geoquimi/geofluids.htm Dr Bill Austin, wena@st- andrews.ac.uk Dr James Scourse, 31st Int'l GEOLOGICAL [email protected] CONGRESS - Geology and

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