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| Titel |
Impact of western Siberia heat wave 2012 on greenhouse gases and trace metal concentration in thaw lakes of discontinuous permafrost zone |
| VerfasserIn |
O. S. Pokrovsky, L. S. Shirokova, S. N. Kirpotin, S. P. Kulizhsky, S. N. Vorobiev |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 8 ; Nr. 10, no. 8 (2013-08-09), S.5349-5365 |
| Datensatznummer |
250085289
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| Publikation (Nr.) |
 copernicus.org/bg-10-5349-2013.pdf |
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| Zusammenfassung |
| During the anomalously hot summer in 2012, surface air temperatures in
Western Siberia were 5 to 15 °C higher than those observed during
the previous period of > 30 yr. This unusual climate phenomenon provided
an opportunity to examine the effects of short-term natural heating of water
in thermokarst ponds and lakes in discontinuous permafrost zones and compare
these observations to previous field results obtained when the temperature
was normal during the summer of 2010 in the same region. In 2012, thermokarst
bodies of water shrank significantly, water levels dropped approximately
50 cm in large lakes and small (< 10–100 m2) ponds, and shallow
soil depressions disappeared. Based on samples from ~ 40 bodies of
water collected previously and in 2012, first-order features of changes in
chemical composition in response to increased water temperatures (from
14.1 ± 2.2 to 23.8 ± 2.3 °C in 2010 and 2012,
respectively) were established. In these thermokarst bodies of water that
covered a full range of surface areas, the average conductivity and pH were
almost unchanged, whereas dissolved organic carbon (DOC), Cl- and
SO42- concentrations were higher by a factor of ~ 2 during
summer 2012 compared to periods with normal temperatures. Similarly, most
divalent metals and insoluble trivalent and tetravalent elements were more
concentrated by a factor of 1.7–2.4 in the summer of 2012 than normal
periods. The average concentrations of dissolved CO2 and CH4 during
the hot summer of 2012 increased by factors of 1.4 and 4.9, respectively. For
most of the trace elements bound to colloids, the degree of colloidal binding
decreased by a factor of 1.44 ± 0.33 (for an average of 40 elements)
during the hot summer of 2012 compared to normal periods. Increases in
CO2 and CH4 concentrations with the decreasing size of the body of
water were well-pronounced during the hot summer of 2012. The concentrations
of CO2 and CH4 rose by factors of 5 and 150, respectively, in small
(≤ 102 m2) compared to large (≥ 104 m2)
thermokarst (thaw) lakes. Taken together, these trends suggest that, for a
conservative scenario of lake size distribution, lake water warming at high
latitudes will produce (1) a significant increase in methane emission
capacity from thaw lake surfaces; (2) decreased molecular sizes of trace
element complexes and potential bioavailability of metal micronutrients in
water columns; and (3) relatively conservative responses by CO2, DOC and
trace element concentrations. |
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