The fate of the submarine ikaite tufa columns in southwest Greenland under changing climate conditions.
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The fate of the submarine ikaite tufa columns in southwest Greenland under changing climate conditions. / Hansen, Marc O.; Buchardt, Bjørn; Kühl, Michael; Elberling, Bo.
I: Journal of Sedimentary Research, Bind 81, Nr. 8, 2011, s. 553-561.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The fate of the submarine ikaite tufa columns in southwest Greenland under changing climate conditions.
AU - Hansen, Marc O.
AU - Buchardt, Bjørn
AU - Kühl, Michael
AU - Elberling, Bo
PY - 2011
Y1 - 2011
N2 - Ikaite is considered a metastable mineral forming and stable only at low temperatures and therefore an indicatorof low-temperature carbonate precipitation often associated with cold marine seeps. It is found world-wide but mostspectacularly in Ikka Fjord in southwest Greenland as submarine carbonate tufa columns. Here, ikaite is formed as a result ofsubmarine spring water mixing with cold seawater. As ikaite disintegrates at temperatures above 6–7uC, it has been speculatedthat global warming could endanger this unique habitat as well as other sites. In Ikka Fjord in situ water chemistry in andaround an ikaite column measured continuously over two years showed that the column water is alkaline (pH . 9–10)throughout the year with temperatures of 21.3–6.0 uC and conductivities of 5.7–7.9 mS cm21, favoring year-round growth ofcolumns at 4–5 cm per month. Short-term in situ measurements with needle micro sensors from both older dehydrated andcalcified parts and more recently formed solid parts of an ikaite tufa column showed similar pH and temperature values,including a temperature variation over the tidal cycle. In the uppermost, recently deposited ikaite matrix, spring water escapingat the top causes passive drag of seawater into the porous ikaite matrix, leading to a mixing layer several centimeters thick thathas pH values intermediate to the spring water in the column and the surrounding seawater. We conclude that the main part ofthe columns, consisting of fossilized ikaite (inverted to calcite) partly sealed by calcifying coralline algae and with year-roundflow of alkaline freshwater through distinct channels, are resistant to warming. In the more diffuse top part of the columns, theformation of ikaite, and thus column growth, will be limited in the future due to increased fjord water temperature during the, 3 summer months a year
AB - Ikaite is considered a metastable mineral forming and stable only at low temperatures and therefore an indicatorof low-temperature carbonate precipitation often associated with cold marine seeps. It is found world-wide but mostspectacularly in Ikka Fjord in southwest Greenland as submarine carbonate tufa columns. Here, ikaite is formed as a result ofsubmarine spring water mixing with cold seawater. As ikaite disintegrates at temperatures above 6–7uC, it has been speculatedthat global warming could endanger this unique habitat as well as other sites. In Ikka Fjord in situ water chemistry in andaround an ikaite column measured continuously over two years showed that the column water is alkaline (pH . 9–10)throughout the year with temperatures of 21.3–6.0 uC and conductivities of 5.7–7.9 mS cm21, favoring year-round growth ofcolumns at 4–5 cm per month. Short-term in situ measurements with needle micro sensors from both older dehydrated andcalcified parts and more recently formed solid parts of an ikaite tufa column showed similar pH and temperature values,including a temperature variation over the tidal cycle. In the uppermost, recently deposited ikaite matrix, spring water escapingat the top causes passive drag of seawater into the porous ikaite matrix, leading to a mixing layer several centimeters thick thathas pH values intermediate to the spring water in the column and the surrounding seawater. We conclude that the main part ofthe columns, consisting of fossilized ikaite (inverted to calcite) partly sealed by calcifying coralline algae and with year-roundflow of alkaline freshwater through distinct channels, are resistant to warming. In the more diffuse top part of the columns, theformation of ikaite, and thus column growth, will be limited in the future due to increased fjord water temperature during the, 3 summer months a year
U2 - 10.2110/jsr.2011.50
DO - 10.2110/jsr.2011.50
M3 - Journal article
VL - 81
SP - 553
EP - 561
JO - Journal of Sedimentary Research
JF - Journal of Sedimentary Research
SN - 1527-1404
IS - 8
ER -
ID: 23348502