37 research outputs found
Landform partitioning and estimates of deep storage of soil organic matter in Zackenberg, Greenland
Particulate organic matter in the Lena River and its delta: from the permafrost catchment to the Arctic Ocean
Rapid Arctic warming accelerates permafrost thaw, causing
an additional release of terrestrial organic matter (OM) into rivers and,
ultimately, after transport via deltas and estuaries, to the Arctic Ocean
nearshore. The majority of our understanding of nearshore OM dynamics and
fate has been developed from freshwater rivers despite the likely impact of
highly dynamic estuarine and deltaic environments on the transformation,
storage, and age of OM delivered to coastal waters. Here, we studied
particulate organic carbon (POC) dynamics in the Lena River delta and compared them
with POC dynamics in the Lena River main stem along a ∼ 1600 km long
transect from Yakutsk, downstream to the delta. We measured POC, total
suspended matter (TSM), and carbon isotopes (δ13C and Δ14C) in POC to compare riverine and deltaic OM composition and changes
in OM source and fate during transport offshore. We found that TSM and POC
concentrations decreased by 70 % during transit from the main stem to
the delta and Arctic Ocean. We found deltaic POC to be strongly depleted in
13C relative to fluvial POC. Dual-carbon (Δ14C and δ13C) isotope mixing model analyses indicated a significant
phytoplankton contribution to deltaic POC (∼ 68 ± 6 %) and
suggested an additional input of permafrost-derived OM into deltaic waters
(∼ 18 ± 4 % of deltaic POC originates from Pleistocene
deposits vs. ∼ 5 ± 4 % in the river main stem). Despite the
lower concentration of POC in the delta than in the main stem (0.41 ± 0.10 vs. 0.79 ± 0.30 mg L−1, respectively), the amount of
POC derived from Yedoma deposits in deltaic waters was almost twice as large
as the amount of POC of Yedoma origin in the main stem (0.07 ± 0.02 and 0.04 ± 0.02 mg L−1, respectively). We assert that estuarine and deltaic
processes require consideration in order to correctly understand OM dynamics
throughout Arctic nearshore coastal zones and how these processes may evolve
under future climate-driven change.</p
Prune Belly Syndrome: Treatment of Terminal Renal Failure by Hemodialysis and Renal Transplantation
Landform partitioning and estimates of deep storage of soil organic matter in Zackenberg, Greenland
Soils in the northern high latitudes are a key component in the global carbon
cycle, with potential feedback on climate. This study aims to improve the
previous soil organic carbon (SOC) and total nitrogen (TN) storage estimates
for the Zackenberg area (NE Greenland) that were based on a land cover
classification (LCC) approach, by using geomorphological upscaling. In
addition, novel organic carbon (OC) estimates for deeper alluvial and deltaic
deposits (down to 300 cm depth) are presented. We hypothesise that landforms
will better represent the long-term slope and depositional processes that
result in deep SOC burial in this type of mountain permafrost environments.
The updated mean SOC storage for the 0–100 cm soil depth is 4.8 kg C m−2,
which is 42 % lower than the previous estimate of 8.3 kg C m−2
based on land cover upscaling. Similarly, the mean soil TN storage
in the 0–100 cm depth decreased with 44 % from 0.50 kg (± 0.1 CI) to
0.28 (±0.1 CI) kg TN m−2. We ascribe the differences to a
previous areal overestimate of SOC- and TN-rich vegetated land cover classes.
The landform-based approach more correctly constrains the depositional areas
in alluvial fans and deltas with high SOC and TN storage. These are also
areas of deep carbon storage with an additional 2.4 kg C m−2 in the
100–300 cm depth interval. This research emphasises the need to consider
geomorphology when assessing SOC pools in mountain permafrost landscapes