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Incorporation and preservation of geochemical fingerprints in peat archives

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Department of Ecology and Environmental Science Umeå University

Umeå 2013

Incorporation and preservation of geochemical fingerprints in peat archives

Sophia V. Hansson

Akademisk avhandling

som med vederbörligt tillstånd av Rektor vid Umeå universitet för avläggande av filosofie doktorsexamen framläggs till offentligt försvar i Lilla Hörsalen (KB3A9), KBC,

fredagen den 24 januari, kl. 10:00.

Avhandlingen kommer att försvaras på engelska.

Fakultetsopponent: Dr. Dominik J. Weiss,

Department of Earth Sciences and Engineering,

Imperial College London, Royal School of Mines,

London, United Kingdom

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Organization Document type Date of publication

Umeå University Doctoral thesis 17 December 2013

Department of Ecology &

Environmental Science

Author Sophia V. Hansson

Title

Incorporation and preservation of geochemical fingerprints in peat archives.

Abstract

The present status of the environment, including environmental problems such as heavy metal accumulation in aquatic and terrestrial ecosystems, is in part the consequence of long-term changes. Cores from peatlands and other natural archives provide us with the potential to study aspects of the atmospheric cycling of elements, such as metal pollutants, on timescales much longer than the decade or two available to us with atmospheric deposition monitoring programs. The past decade especially has seen a rapid increase in interest in the biogeochemical record preserved in peat, particularly as it relates to environmental changes (e.g. climate and pollution). Importantly, recent studies have shown that carbon dynamics, i.e., organic matter decomposition, may influence the record of atmospherically derived elements such as halogens and mercury.

Other studies have shown that under certain conditions some downward movement of atmospherically deposited elements may also occur, which adds complexity to establishing reliable chronologies as well as inherent problems of estimating accurate accumulation rates of peat and past metal deposition. Thus, we still lack a complete understanding of the basic biogeochemical processes and their effects on trace element distributions. While many studies have validated the general temporal patterns of peat records, there has been a limited critical examination of accumulation records in quantitative terms. To be certain that we extract not only a qualitative record from peat, it is important that we establish a quantitative link between the archive and the few to several decades of data that are available from contemporary monitoring and research.

The main objective of this doctoral thesis was to focus on improving the link between the long-term paleorecord and the contemporary monitoring data available from biomonitoring and direct deposition observations. The main research questions have therefore been: Are peat archives an absolute or relative record? And how are geochemical signals, including dating, incorporated in the peat archive? What temporal resolution is realistic to interpret by using peat cores?

Keywords

Peat, Beryllium, bulk density, C/N-ratio, decomposition, deposition, downwash, elemental mobility, geochemistry, humification, lead, light transmission, mercury, peat accumulation, precipitation.

Language ISBN Number of pages English 978-91-7459-779-0 36 + 4 papers

References

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