Magnetic, geochemical and DNA properties of highly magnetic soils in England
Magnetic, geochemical and DNA properties of highly magnetic soils in England
A range of mineral magnetic, Mössbauer, geochemical, microscopy and molecular biological techniques are applied to a small set of bulk and fine fractions of highly magnetic English topsoils that overlie weakly magnetic sedimentary geologies. Results show that the ferrimagnetic component of highly enhanced surface soils is dominated by superparamagnetic (SP) grains with a minor proportion of larger stable single-domain/pseudo-single-domain (SSD/PSD) grains that may derive from magnetosomes and magnetic inclusions. DNA screening of the soils by polymerase chain reaction (PCR) shows that the concentration of viable magnetotactic bacteria is too low (normally <?102?bacteria?g?1) to explain the high concentrations of ferrimagnetic minerals observed. There does not appear to be any strong causative relationship between the presence or concentration of Magnetospirillum sp. and soil magnetic properties. Microcosm experiments were able to show that the destructive effects of waterlogging on secondary ferrimagnetic mineral (SFM) formation are rapid and associated with significant changes in bacterial populations. The combined results are used to examine alternative explanations for SFM formation and are consistent with previous findings (Dearing et al. 1996b, 1997) that ferrihydrite may be an important precursor of bacterially mediated magnetite in strongly magnetic temperate soils—a process driven by the rate of Fe flux to the biologically active surface soil.
dna, magnetotactic bacteria, mössbauer soil magnetism
183-196
Dearing, J.A.
dff37300-b8a6-4406-ad84-89aa01de03d7
Hannam, J.A.
62b17b22-42da-4d8c-9333-1300d69c358a
Anderson, A.S.
dc723700-b7c4-44fc-abad-ddbd01052151
Wellington, E.M.H.
04bf3e69-9764-42aa-a1f2-a3b88bf76bec
January 2001
Dearing, J.A.
dff37300-b8a6-4406-ad84-89aa01de03d7
Hannam, J.A.
62b17b22-42da-4d8c-9333-1300d69c358a
Anderson, A.S.
dc723700-b7c4-44fc-abad-ddbd01052151
Wellington, E.M.H.
04bf3e69-9764-42aa-a1f2-a3b88bf76bec
Dearing, J.A., Hannam, J.A., Anderson, A.S. and Wellington, E.M.H.
(2001)
Magnetic, geochemical and DNA properties of highly magnetic soils in England.
Geophysical Journal International, 144 (1), .
(doi:10.1046/j.0956-540X.2000.01312.x).
Abstract
A range of mineral magnetic, Mössbauer, geochemical, microscopy and molecular biological techniques are applied to a small set of bulk and fine fractions of highly magnetic English topsoils that overlie weakly magnetic sedimentary geologies. Results show that the ferrimagnetic component of highly enhanced surface soils is dominated by superparamagnetic (SP) grains with a minor proportion of larger stable single-domain/pseudo-single-domain (SSD/PSD) grains that may derive from magnetosomes and magnetic inclusions. DNA screening of the soils by polymerase chain reaction (PCR) shows that the concentration of viable magnetotactic bacteria is too low (normally <?102?bacteria?g?1) to explain the high concentrations of ferrimagnetic minerals observed. There does not appear to be any strong causative relationship between the presence or concentration of Magnetospirillum sp. and soil magnetic properties. Microcosm experiments were able to show that the destructive effects of waterlogging on secondary ferrimagnetic mineral (SFM) formation are rapid and associated with significant changes in bacterial populations. The combined results are used to examine alternative explanations for SFM formation and are consistent with previous findings (Dearing et al. 1996b, 1997) that ferrihydrite may be an important precursor of bacterially mediated magnetite in strongly magnetic temperate soils—a process driven by the rate of Fe flux to the biologically active surface soil.
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Published date: January 2001
Additional Information:
The first application of DNA sequencing to elucidate the origins of magnetic minerals in soil and loess (funded by NERC), particularly the role of magnetotactic bacteria. It led directly to an approach from UK DSTL to conduct research into soil magnetism and landmine detection (now funded by NERC).
Keywords:
dna, magnetotactic bacteria, mössbauer soil magnetism
Identifiers
Local EPrints ID: 46754
URI: http://eprints.soton.ac.uk/id/eprint/46754
ISSN: 0956-540X
PURE UUID: 2506929f-6d95-4035-b222-b0ddce594721
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Date deposited: 17 Jul 2007
Last modified: 16 Mar 2024 03:38
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Contributors
Author:
J.A. Hannam
Author:
A.S. Anderson
Author:
E.M.H. Wellington
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