Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena River and coastal erosion in the southeast Laptev Sea
A.N. Charkin, O.V. Dudarev, I.P. Semiletov, A.V. Kruhmalev, J. Vonk, L. Sánchez-García, E. Karlsson, Ö. Gustafsson . Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena River and coastal erosion in the southeast Laptev Sea. Biogeosciences. 2011, Vol. 8, p. 2581-2011.
Climate warming is amplified in the land-sea system
of the East Siberian Arctic, which also holds large pools
of vulnerable carbon in permafrost. This coastal area is
strongly influenced by sediment and carbon transport from
both its large rivers and extensive erosion of Pleistocene permafrost
along its coastline. This study is investigating the
coastal fate of the sediment and organic carbon delivered to
the Buor-Khaya Gulf, which is the first recipient of the overwhelming
fluvial discharge from the Lena River and is additionally
receiving large input from extensive erosion of the
coastal ice-complex (permafrost a.k.a. Yedoma; loess soil
with high organic carbon content). Both water column suspended
particulate matter (SPM) and surface sediments were
sampled at about 250 oceanographic stations in the Gulf in
this multi-year effort, including one winter campaign, and
analyzed for the distribution and sorting of sediment size, organic
carbon content, and stable carbon isotope signals. The
composition of the surface sediment suggests an overwhelmingly
terrestrial contribution from both river and coastal erosion.
The objective of this paper is to improve our understanding
of the seasonal (i.e., winter vs summer) and interannual
variability of these coastal sedimentation processes and
the dynamics of organic carbon (OC) distribution in both the
water column SPM and the surface sediments of the Buor-
Khaya Gulf.
Based on data collected during several years in the pe-
riod 2000–2008, two different sedimentation regimes were
revealed for the Buor-Khaya Gulf, the relative importance
of each at a given time depend on hydrometeorological con-
ditions, the Lena River water discharge and sea-ice regime:
Type 1 erosion-accumulation and Type 2 accumulation.
The Type 1 erosion-accumulation sedimentation regime is
typical (2000–2006) for the ice-free period of the year (here
considered in detail for August 2005). Under such condi-
tions terrigenous sources of SPM and particulate organic car-
bon (POC) stem predominantly from river discharge, thermal
erosion of coastal ice-complex and remobilized bottom sed-
iments. The Type 2 accumulation sedimentation regime de-
velops under ice-covered conditions, and only occasionally
during the ice-free period (August 2008). In Type 2 winter,
combined terrigenous and marine-biogenic SPM and POC
sources are dominating due to relatively low overall terrige-
nous input (April 2007). In Type 2 summer, river alluvium
becomes the major SPM and POC source (August 2008).
The water column SPM and POC loadings vary by more than
a factor of two between the two regimes. This study under-
scores the necessity of multi-year investigations to better un-
derstand the functioning of the primary recipient of terrestri-
ally expulsed matter in the East Siberian Arctic.
Climate warming is amplified in the land-sea system
of the East Siberian Arctic, which also holds large pools
of vulnerable carbon in permafrost. This coastal area is
strongly influenced by sediment and carbon transport from
both its large rivers and extensive erosion of Pleistocene permafrost
along its coastline. This study is investigating the
coastal fate of the sediment and organic carbon delivered to
the Buor-Khaya Gulf, which is the first recipient of the overwhelming
fluvial discharge from the Lena River and is additionally
receiving large input from extensive erosion of the
coastal ice-complex (permafrost a.k.a. Yedoma; loess soil
with high organic carbon content). Both water column suspended
particulate matter (SPM) and surface sediments were
sampled at about 250 oceanographic stations in the Gulf in
this multi-year effort, including one winter campaign, and
analyzed for the distribution and sorting of sediment size, organic
carbon content, and stable carbon isotope signals. The
composition of the surface sediment suggests an overwhelmingly
terrestrial contribution from both river and coastal erosion.
The objective of this paper is to improve our understanding
of the seasonal (i.e., winter vs summer) and interannual
variability of these coastal sedimentation processes and
the dynamics of organic carbon (OC) distribution in both the
water column SPM and the surface sediments of the Buor-
Khaya Gulf.
Based on data collected during several years in the pe-
riod 2000–2008, two different sedimentation regimes were
revealed for the Buor-Khaya Gulf, the relative importance
of each at a given time depend on hydrometeorological con-
ditions, the Lena River water discharge and sea-ice regime:
Type 1 erosion-accumulation and Type 2 accumulation.
The Type 1 erosion-accumulation sedimentation regime is
typical (2000–2006) for the ice-free period of the year (here
considered in detail for August 2005). Under such condi-
tions terrigenous sources of SPM and particulate organic car-
bon (POC) stem predominantly from river discharge, thermal
erosion of coastal ice-complex and remobilized bottom sed-
iments. The Type 2 accumulation sedimentation regime de-
velops under ice-covered conditions, and only occasionally
during the ice-free period (August 2008). In Type 2 winter,
combined terrigenous and marine-biogenic SPM and POC
sources are dominating due to relatively low overall terrige-
nous input (April 2007). In Type 2 summer, river alluvium
becomes the major SPM and POC source (August 2008).
The water column SPM and POC loadings vary by more than
a factor of two between the two regimes. This study under-
scores the necessity of multi-year investigations to better un-
derstand the functioning of the primary recipient of terrestri-
ally expulsed matter in the East Siberian Arctic.