Máster Universitario en Cambio Global
Doctorado
Programa Oficial de Posgrado adaptado al EEES
Peat as an
organic record
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat Society Clip
Peat
Description
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Peat accumulates at a rate of
about 0.5 - 1 mm per year (or 5-10
mover 10,000 years) with strong
local variations. Peat can be
formed from mosses, lichens,
sedges, grasses, shrubs (heather)
or trees. In northern regions,
mosses are the main peat-forming
plants while trees are the main
ones in the tropics. Most
peatlands that exist today formed
in the last 15,000 years since the
last Ice Age.
Peat consists of accumulated dead
plant material of which at least
50% is carbon.
Water saturation means that plant
remains decompose slowly and
form peat
Peat moss
Sphagnum flexuosum
Lichen in peat
Sphagnum spp. Moss peat
with sedges of Carex spp.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat
Distribution of the record
• Peat has been forming in the
planet during the last 360
Million yr and nowadays
holds 550 Gt of carbon
(1015g).
• Worldwide peatlands cover
about 500 million hectares
of land, some 5-8% of the
world's surface.
• They are most extensive in
North America, Asia and
Europe.
• The remainder are found in
tropical areas the most
extensive in south-east Asia.
• Overall, hold 10% of
freshwater world’s
resources.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
In Europe there are 515,000 km2, around 15%
In Spain around 300 km2 ( 0.05% !!)
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat (=turf, e.g, in Ireland)
Peat types
Elevated Bog
Peatland an area with a naturally
accumulated peat layer at the
surface
Mire a peatland where peat is
currently forming and
accumulating
Bog, pH 3.2 to 4.2; Ash 3%
a
peatland which receives water
solely from rain and/or snow
falling on its surface. Poor trophic
status. Up to 12 m thick!!
Fen
Blanket Bog
Fen pH 7 to 8; Ash 10%
a
peatland which receives water and
abundant nutrients from the soil,
rock and groundwater as well as
rain and/or snow. Up to 2 m.
Fen
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat
Structure
• Bogs: 98% water! Only 2% solids.
• Fens: 85% / 15%
• A bog consists of two layers:
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the upper, very thin layer,
known as the acrotelm, is only
some 30cm deep, and consists
of upright stems of the
Sphagnum mosses, largely still
alive and colourful with their
red, yellows and ochre. Water
can move rapidly through this
layer.
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Below this is a very much thicker bulk of peat, known as the catotelm, where
individual plant stems have collapsed under the weight of mosses above them to
produce an amorphous, chocolate-coloured mass of Sphagnum fragments. here the
water slowly seeps down through the bog over several weeks or even months.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat
Peat formation
Peatlands are composed of
deep layers of waterlogged
peat and a surface layer of
living vegetation. Peat
consists of the dead remains
of plants (and to a lesser
extent of animals) that have
accumulated over thousands
of years. Peat accumulates in
areas where the rate of plant
production exceeds the rate
of plant decomposition.
Complete plant
decomposition is prevented in
areas where waterlogging
occurs.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat
Proxies
Water table oscillations
throuhg the fossil record
Testate amoeba
Testate amoebae are routinely used
as indicators of past changes in
peatland hydrology. These singlecelled organisms respond quickly
to environmental change, produce
decay-resistant and taxonomically
distinctive shells and are generally
well preserved and abundant in
Holocene peat deposits. In
oligotrophic peatlands, testate
amoeba community composition is
primarily controlled by the
moisture content of the surface
peat, allowing the development of
transfer functions to bdepths.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
• Some bogs are uniquely
suited to natural and
anthropogenic airborne
particles because their
surface layers are only fed
by atmospheric inputs
(rain, snow, fog, dust).
• Pb is well retained by bogs
(adequate pH).
• Stable isotopes allow
discriminating between
natural and anthropogenic
metal abundance, and its
origin.
• Metal/Titanium
(conservative metal),
allows such discrimination.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
De Vleeschouwer et al 2010
Peat
Application examples
Peat as an archive of
atmospheric pollution
Peat
Application examples
Peat pollen record as a
paleothermometer
• Pollen-based warm season
temperature
reconstruction
• Upper panel is detrended
to remove human effects
(de- or re-forestation).
• Reconstructed detrended
series are compared to
instrumentally measured
temperatures.
• Correlation begins to be
good in 1900 at a decadal
resolution.
Lamentowicz et al 2010
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat
Application examples
Peat proxies record solar
activity
• Proxies:
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Normalized testate
amoebae water table
reconstruction (blue)
Plant macrofossil Dupont
wetness index (green)
Normalized 14C relative
production rate
(accretion) (gray)
• Historical solar minima are
indicated, and arrows
show significant raises in
water table.
• Low solar activity results in
wetter seasons/periods,
increasing the water table
and consequently, bog
accretion (production).
Chambers et al 2010
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
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Water table changes (WTC) of
several bogs in North America
during the last 3000 years (a)
Microcharcoal particles reveal fire
destroying the bog in Michigan
(blue) and allows establishing
recovery time (resilience; paleoecology).
Statitical removal of long term
patterns allows building a
composite record of all three bogs
(b).
WTC tightly matches the severe
drought periods (yellow).
Tree rings and dune activity
(aeolian transport) match drought
periods too.
Reconstructions of anomalous SST
both in the Pacific and in the
Atlantic, and of the NAO (Niño)
using tree-reings, support all
previous proxies and records.
MCA: Medieval Climate Anomaly; PDO: Pacific Decadal Oscillation
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Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat serve to cross-test global climate
hypotheses (Booth et al 2010)
Peat
Application examples
Peat
Application examples
Hg as pollution and
temperature proxy
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Galician peat records net
accumulation of atmospheric
Hg during the last 4000 years.
Differences in thermal lability
of Hg allowed a quantitative
paleotemperature
reconstruction during that
period.
Natural Hg can be
distinguished from
anthropogenic Hg, allowing to
establish background levels
and record mining activities.
Discriminant analysis allowed
to build a relative scale of
temperature (Temperature
index).
Martínez-Cortizas et al. 1999
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat as a paleo-record
Literature and web sites
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Dise, N.B, 2009: Peatland responses to global change, Science, 326: 810-811.
Booth, R.K., 2008: Testate amoebae as proxies of mean annual water-table depth in Sphagnum-dominated
peatlands of North America, Journal of Quaternary Science, 23: 43-57.
Booth, R.K., 2010: Testing the climate sensitivity of peat-based paleoclimate reconstructions in midcontinental North America, Quaternary Science Reviews, 29: 720-731. doi:
10.1016/j.quascirev.2009.11.018
Barber, K.E., 1981: Peat Stratigraphy and Climatic Change—a Palaeoecological Test of the Theory of Cyclic
Peat Bog Regeneration, A A Balkema, Rotterdam.
Vleeschouwer et al., 2010: Peat as an archive of atmospheric pollution and environmental change: a case
study of lead in Europe. PAGES, 18: 20-22.
The Holocene 2001, volume 11, number 5, includes various articles using peat as a paleorecord.
http://www.lehigh.edu/~rkb205/ (Robert K. Booth web site).
http://www.peat-portal.net/index.cfm?&menuid=115&parentid=113
http://www.ipcc.ie/wptourhome1.html (peatlands around de world)
http://www.doeni.gov.uk/niea/biodiversity/habitats-2/peatlands/about_peatlands.htm
(‘about peatlands’)
http://www.landforms.eu/Caithness/Peat%20formation.htm (peat structure)
http://www.imcg.net/pages/publications/papers.php?lang=EN (Int. Mire Cons. Group; bibliography)
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
Peat as a paleo-record
Literature and web sites
Antonio Martínez-Cortizas: Spanish specialist in the use of peat as a paleorecord.
Universidad de Santiago de Compostela, Depto. Edafología y Química Agrícola
[email protected]
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Martínez Cortizas A, Pontevedra-Pombal X, García-Rodeja E, Nóvoa-Muñoz JC, Shotyk, W (1999) Mercury
in a Spanish peat bog: archive of climate change and atmospheric metal deposition. Science 284:939–42.
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Martínez Cortizas A, Pontevedra-Pombal X, Nóvoa-Muñoz JC, García-Rodeja E. Four thousand years of
atmospheric Pb, Cd and Zn deposition recorded by the ombrotrophic peat bog of Penido Vello
(Northwestern Spain) (1997). Water Air Soil Poll, 100:387–403.
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Martínez Cortizas A, García-Rodeja E, Pontevedra-Pombal X, Nóvoa-Muñoz JC, Weis D, Cheburkin A (2002)
Atmospheric Pb deposition in Spain during the last 4600 years recorded by two ombrotrophic peat bogs
and implications for the use of peat as archive. Sci Total Environ, 292:33–44.
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Martínez Cortizas A, Pontevedra X, Nóvoa JC, Peiteado E, Piñeiro R (2005) Linking changes in atmospheric
dust deposition, vegetation change and human activities in north-western Spain during the last 5300
years. The Holocene, 15:698–706.
Miguel Ángel Mateo Mínguez - Centro de Estudios Avanzados de Blanes - CSIC
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Peat Dsitribution and description of the record