 |
| Titel |
The contribution of micrometeorites to the iron stocks of buried podzols, developed in Late-glacial aeolian sand deposits (Brabant, The Netherlands) |
| VerfasserIn |
Jan van Mourik, Sebastiaan de Vet |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102165
|
| Publikation (Nr.) |
 EGU/EGU2015-1446.pdf |
|
|
|
|
|
| Zusammenfassung |
| The surface geology of an extensive part of NW-Europe is dominated by coversands
(Late-glacial chemical poor aeolian sand deposits). The geomorphology of coversand
landscapes is dominated by ridges and planes. Podzolation is the dominant soil forming
process in coversands under moderate humid climatic conditions. Umbric Podzols developed
on the ridges under Quercetum-mixtum, Gleyic and Histic Podzols developed in the planes
under Alnetum. Even in chemical poor coversands, iron will be released by hydrolysis from
iron containing silicate minerals (such as feldspars). It is well known that the vertical iron
distribution in Podzols is effected by translocation of active iron from eluvial to illuvial
horizons and that iron is leaching to the aquifer. Iron stocks of Podzols, in contrasts, have not
been widely studied for comparison purposes of individual soil horizons or between soils. We
determined the stocks of active and immobile iron in the horizons of buried xeromorphic
Podzols (soils that developed without any contact with groundwater). The results show that
the total amount of iron exceeds the potential amount which can be released by
hydrolysis from the parent material. Furthermore, to amount of iron that leached to the
groundwater is unknown. It is evident that we must find an additional source to
explain the total iron stocks in buried Podzols. It is known from analysis of ice
cores that the earth atmosphere is subjected to a continuous influx of (iron rich)
micrometeorites. The precipitation of micrometeorites (and other aerosols) on the earth
surface is concentrated in humid climatic zones with (intensive) rain fall. We analyzed
minerals, extracted from the ectorganic horizon of the Initial Podzols, developed in
driftsand that stabilized around 1900 AD, overlying Palaeopodzols, buried around 1200
AD. Among blown in quartz grains, we could determine also micrometeorites,
embedded in the organic skeleton of the fermentation horizon of the Initial Podzol
(Mormoder). The exogenic origin of the micrometeorites could be confirmed by
SEM-EDX analysis. Micrometeorites could accumulate on the surface level of the
Initial Podzols during one century (between 1900 AD till the moment of sampling in
2013), on the surface level of the buried Podzols during eight millennia (between the
moment of stabilization in the Preboreal and the moment of burying around 1200
AD). The soil conditions of the ectorganic horizons of (initial) Podzols are moist
and acidic, promoting quick release of iron from micrometeorites. An additional
source of Iron that could be added to the amount, released from the parent material.
The extraction and identification of micrometeorites from ectorganic horizons of
Initial Podzols helped illustrate that atmospheric deposition in the form of aerosol
and aeolian (e.g. Saharan) dust, micrometeorites and other hydrolysable particles,
contributes to soil development. The requisite active iron for podzolation can therefore be
derived from chemical weathering of atmospheric iron sources in the acidic soil
environment.
Reference: 1. Van Mourik, J.M., Seijmonsbergen, A.C., Slotboom, R.T. and Wallinga, J.,
2012. The impact of human land use on soils and landforms in cultural landscapes on aeolian
sandy substrates (Maashorst, SE Netherlands). Quaternary International 265, 74-89. 2. Van
Mourik, J.M. and de Vet, S.B. (2015). Iron stocks of buried Podzols: endogenic iron deficits
and potential exogenic enrichment in the Maashorst region, SE Netherlands. Catena,
accepted. |
|
|
|
|
|
|