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| Titel |
Space–time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay and adjacent part of the Laptev Sea |
| VerfasserIn |
I. P. Semiletov, N. E. Shakhova, I. I. Pipko, S. P. Pugach, A. N. Charkin, O. V. Dudarev, D. A. Kosmach, S. Nishino |
| 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. 9 ; Nr. 10, no. 9 (2013-09-11), S.5977-5996 |
| Datensatznummer |
250085330
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| Publikation (Nr.) |
 copernicus.org/bg-10-5977-2013.pdf |
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| Zusammenfassung |
| This study aims to improve understanding of carbon cycling in the Buor-Khaya
Bay (BKB) and adjacent part of the Laptev Sea by studying the inter-annual,
seasonal, and meso-scale variability of carbon and related hydrological and
biogeochemical parameters in the water, as well as factors controlling carbon
dioxide (CO2) emission. Here we present data sets obtained on summer
cruises and winter expeditions during 12 yr of investigation. Based on
data analysis, we suggest that in the heterotrophic BKB area, input of
terrestrially borne organic carbon (OC) varies seasonally and inter-annually
and is largely determined by rates of coastal erosion and river discharge.
Two different BKB sedimentation regimes were revealed: Type 1 (erosion
accumulation) and Type 2 (accumulation). A Type 1 sedimentation regime occurs
more often and is believed to be the quantitatively most important mechanism
for suspended particular matter (SPM) and particulate organic carbon (POC)
delivery to the BKB. The mean SPM concentration observed in the BKB under a
Type 1 regime was one order of magnitude greater than the mean concentration
of SPM (~ 20 mg L−1) observed along the Lena River stream in
summer 2003. Loadings of the BKB water column with particulate material vary
by more than a factor of two between the two regimes. Higher partial pressure
of CO2 (pCO2), higher concentrations of nutrients, and lower
levels of oxygen saturation were observed in the bottom water near the eroded
coasts, implying that coastal erosion and subsequent oxidation of eroded
organic matter (OM) rather than the Lena River serves as the predominant
source of nutrients to the BKB. Atmospheric CO2 fluxes from the sea
surface in the BKB vary from 1 to 95 mmol m−2 day−1 and are
determined by specific features of hydrology and wind conditions, which
change spatially, seasonally, and inter-annually. Mean values of CO2
emission from the shallow Laptev Sea were similar in September 1999 and 2005
(7.2 and 7.8 mmol m−2 day−1, respectively), while the CO2
efflux can be one order lower after a strong storm such as in September 2011.
Atmospheric CO2 emissions from a thawed coastal ice complex in the BKB
area varied from 9 to 439 mmol m−2 day−1, with the mean value
ranged from 75.7 to 101 mmol m−2 day−1 in two years (September
2006 and 2009), suggesting that at the time of observations the eroded
coastal area served as a more significant source of CO2 to the
atmosphere than the tundra (mean value: 22.7 mmol m−2 day−1) on
the neighboring Primorsky coastal plain (September 2006). The observed
increase in the Lena River discharge since the 1990s suggests that increased
levels of "satellite-derived" annual primary production could be explained
by an increasing load of humic acids delivered to shelf water; in this water
the color resulting from the presence of CDOM (colored dissolved organic
matter) mimics the color resulting from the presence of Chl a when seen
from space. Because the BKB area can be employed as an integrator of ongoing
changes in the surrounding environment, we suggest that under ongoing
changes, more nutrients, products of eroded OC transformation and river
transport, will be delivered to the Arctic Ocean with its shrinking ice
cover, potentially increasing primary production outside of the
shallow East Siberian Arctic Shelf (ESAS). At the same time, because the ESAS
is characterized by very low transparency which limits euphotic layer
thickness, excessive pCO2 will not be utilized by photosynthesis but
will rather be emitted to the atmosphere at increasing rates, affecting
regional CO2 balance. |
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