Fate of natural and anthropogenic particles in peat bogs [Elektronische Ressource] / vorgelegt von Gaël Le Roux

Gael Fouillet

Sujets

• Biologie

Informations

• Publié par: ruprecht-karls-universitat_heidelberg
• Publié le: 01 janvier 2005
• Nombre de lectures: 13
• Langue: English
• Poids de l'ouvrage: 6 Mo

Extrait

FATE OF NATURAL AND ANTHROPOGENIC
PARTICLES IN PEAT BOGS





INAUGURAL – DISSERTATION

Zur
Erlangung der Doktorwürde
der
Naturwissenschaftlich- Mathematischen
Gesamtfakultät
der
Ruprecht-Karls-Universität
Heidelberg






















Vorgelegt von

Gaël Le Roux (MSc. Environmental Geosciences)
aus Paris, Frankreich

Tag der mündlichen Prüfung : 09.05.2005




FATE OF NATURAL AND ANTHROPOGENIC
PARTICLES IN PEAT BOGS


































Gutachter:
Prof. Dr. William Shotyk
Institute of Environmental Geochemistry
Im Neuenheimer Feld 234
D.69120 Heidelberg
Deutschland

HD Dr. Alain Véron
CEREGE-UMR6635
Europôle Med Arbois – BP80
13545 Aix en Provence Cedex 4
Frankreich
“Objectivity cannot be equated with mental
blankness; rather, objectivity resides in
recognizing your preferences and then
subjecting them to especially harsh
scrutiny and also in a willingness to revise
or abandon your theories when the tests
fail (as they usually do).“

Stephen Jay Gould (1941-2002); The
Lying Stones of Marrakech

-Table of contents-

Table ofContets 1
Abstract 3
Zusamenfasung 5

Résumé 7

Introduction and Objectives 9
1.Introduction and background

2.Objectives 16

3.Result 7

4.Studied sites 19


PART 1: Sampling and Analytical Techniques 27
1.1 Suggested protocol for collecting, handling and preparing peat cores and peat samples for
physical, chemical, mineralogical and isotopic analyses 29

1.2 Accurate and precise Pb isotope ratio measurements in environmental samples by MC-ICP-MS
49

206 207 2081.3 Optimising accuracy and precision of lead isotope measurement ( Pb, Pb, Pb) in acid
digests of peat using individual mass discrimination correction 65


PART 2: Investigating Pb atmospheric deposition using peat bogs 79

2.1 Biogeochemistry and cycling of Pb 81

2.2 Recent atmospheric Pb deposition at a rural site in Southern Germany assessed using a peat
core and snow pack, and comparison with other archives 111

2.3 Identifying the sources and timing of ancient and medieval atmospheric lead pollution in
England using a peat profile from Lindow bog, Manchester 125


1PART 3: Fate of minerals in peat bogs 143

3.1 Alteration of inorganic matter in peat bogs 145

3.2 Fate of minerals in the upper part of a peat bog 159


Appendixes 169

A.1 REE compositions of atmospheric deposition entering an ombrotrophic peat bog in Black
Forest (SW Germany): evidence from snow, lichens and mosses 171

A.2 Accumulation rates and predominant atmospheric sources of natural and anthropogenic Hg
and Pb on the Faroe Islands 177

A.3 Comparison of atmospheric deposition of copper, nickel, cobalt, zinc and cadmium recorded by
peat cores from three ombrotrophic bogs in Finland with monitoring data and emissions
records 195

137A.4 Surface distribution of Cs in the Kohlhütte Moor 213

A.5 Microbial investigations in the KM bog 215


Acknowledgements 217








2Fate of natural and anthropogenic particles in peat bogs.


-Abstract-


Investigating atmospheric deposition over a In addition, the rates of atmospheric Pb
scale of millennial period is crucial because humans accumulation at least for the last 6000 years were
are emitting more and more synthetic and natural quantified using peat cores from KM and Lindow
compounds (i.e.: pollutants and/or dust) to the Bog (LDW), England.
environment through the atmosphere. It is therefore In KM, the most recent Pb accumulation rate (2.5
-2 -1 y) is 50 to 200 times greater than the necessary to determine the background deposition mg m
rate of these compounds, to assess their natural “natural” average background rate of atmospheric
-2 -1variations (ie.: temporal and/or spatial) and to Pb accumulation (~20 µg m y ) calculated using
understand the effects of the increased atmospheric “pre-anthropogenic” samples from the same site.
depositions induced by humans on the environment. The core from LDW (Chap.2.3) shows the potential
The primary aim of this work was to improve the of carefully studying Pb distribution in a peat profile
understanding of the processes affecting the fate of for regional paleo-ecology and archaeology. Using
anthropogenic and natural particles in peat bogs, to the Pb/Ti ratio to calculate the rates of
see which geochemical processes can affect the anthropogenic, atmospheric Pb deposition, the core
suitability and accuracy of peat bogs as archives of reveals Pb contamination first appearing in peat
atmospheric deposition, and also the effects of these samples dating from ca. 900 B.C. which clearly pre-
inputs on the bog ecosystem. date Roman mining activities. The timing of the
To test whether peat bogs are accurate archives of ancient and medieval Pb pollution is also directly
208 206Pb atmospheric deposition, Pb distribution was related to socio-economical events. Pb/ Pb and
206 207investigated in Kohlhütte Moor (KM), a bog in Pb/ Pb data indicate that English ores were the
Southern Germany. Pb is a toxic element extensively predominant sources for atmospheric deposition in
dispersed by human activities (Chap.2.1). The England during the pre-Roman, Roman, and
atmospheric Pb record assessed using a peat core medieval periods.
was compared with other archives, including a snow To test whether peat bogs are suitable archives of
pack and previously studied Swiss peat cores atmospheric deposition of minerals and after a
(Chap.2.2). To this end, new improved methods review of the different possible dissolution
both methodically (Chap.1.1) and analytically mechanisms influencing inorganic particles
(Chap.1.2 and Chap.1.3) were developed. Also (Chap.3.1), mineral distributions in the upper part of
particular attention was given to age dating using KM were investigated (Chap.3.2). Similar minerals
210 14Pb and C and the estimation of the Pb to the local granite were identified using X-Ray-
accumulation rate (AR) based on these ages. The Diffraction: most of the minerals are therefore of
-2 -1most recent Pb AR in KM (2.5 mg m y ) is similar local origin. The distribution of quartz and feldspars
to that obtained from the snow pack on the bog is unaffected by the low pH and the abundance of
-2 -1surface (1 to 4 mg m y ). The isotopic composition organic acids, possibly due to the early formation of
of Pb was measured in both the modern and ancient a siliceous layer and/or coating by humic acids.
peat samples as well as in the snow samples, and Therefore the preservation of quartz and feldspars in
clearly shows that recent inputs are dominated by ombrotrophic peat might make bogs useful archives
anthropogenic Pb. The chronology and isotopic of the changing rates of atmospheric dust since the
composition of atmospheric Pb accumulation Last Glacial.
recorded by the peat from the Black Forest is similar In addition, other minerals, calcite and apatite, were
to the chronologies reported earlier using peat cores identified but only in the topmost samples of the
from various Swiss peat bogs and point to a common bog. They probably dissolve comparatively quickly
Pb source to the region for the past 200 years. and thereby influence the chemistry of the surface of
Taken together, the results show that peat cores from the bog releasing nutrients and therefore influencing
ombrotrophic bogs can yield accurate records of the botanical composition of the bog and the rates of
atmospheric Pb deposition, provided that the cores plant growth.
are carefully collected, handled, prepared, and
analysed using appropriate methods.
3 4Fate of natural and anthropogenic particles in peat bogs.


-Zusammenfassung-

Die Untersuchung der atmosphärischen Torfkerne aus Kohlhütte Moor und Lindow Bog
Deposition über eine Zeitspanne von 1000 Jahren ist (LDW), England, quantitativ bestimmt.
von großer Bedeutung, da der Mensch mehr und In Kohlhütte Moor war die aktuelle atmosphärische