Ongoing Buildup of Refractory Organic Carbon in Boreal Soils During the Holocene

Science ◽  
2006 ◽  
Vol 314 (5803) ◽  
pp. 1283-1286 ◽  
Author(s):  
R. H. Smittenberg ◽  
T. I. Eglinton ◽  
S. Schouten ◽  
J. S. S. Damste
Keyword(s):  
Organic Carbon ◽  
The Holocene ◽  
Boreal Soils

Sources of organic carbon and depositional environment in the Bengal delta plain sediments during the Holocene period

Limnology ◽  
2009 ◽  
Vol 11 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Hossain M. Anawar ◽  
Takahito Yoshioka ◽  
Eiichi Konohira ◽  
Junji Akai ◽  
M. C. Freitas ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Depositional Environment ◽  
The Holocene ◽  
Bengal Delta ◽  
Delta Plain ◽  
Holocene Period

scholarly journals Organic carbon and total nitrogen stocks in soils of the Lena River Delta

2013 ◽  
Vol 10 (6) ◽  
pp. 3507-3524 ◽  
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
G. Grosse ◽  
A. Desyatkin ◽  
E.-M. Pfeiffer
Keyword(s):  
Organic Carbon ◽  
Active Layer ◽  
River Delta ◽  
The Arctic ◽  
River Terrace ◽  
Total N ◽  
Lena River ◽  
The Holocene ◽  
Lena River Delta ◽  
N Pool

Abstract. The Lena River Delta, which is the largest delta in the Arctic, extends over an area of 32 000 km2 and likely holds more than half of the entire soil organic carbon (SOC) mass stored in the seven major deltas in the northern permafrost regions. The geomorphic units of the Lena River Delta which were formed by true deltaic sedimentation processes are a Holocene river terrace and the active floodplains. Their mean SOC stocks for the upper 1 m of soils were estimated at 29 kg m−2 ± 10 kg m−2 and at 14 kg m−2 ± 7 kg m−2, respectively. For the depth of 1 m, the total SOC pool of the Holocene river terrace was estimated at 121 Tg ± 43 Tg, and the SOC pool of the active floodplains was estimated at 120 Tg ± 66 Tg. The mass of SOC stored within the observed seasonally thawed active layer was estimated at about 127 Tg assuming an average maximum active layer depth of 50 cm. The SOC mass which is stored in the perennially frozen ground at the increment 50–100 cm soil depth, which is currently excluded from intense biogeochemical exchange with the atmosphere, was estimated at 113 Tg. The mean nitrogen (N) stocks for the upper 1 m of soils were estimated at 1.2 kg m−2 ± 0.4 kg m−2 for the Holocene river terrace and at 0.9 kg m−2 ± 0.4 kg m−2 for the active floodplain levels, respectively. For the depth of 1 m, the total N pool of the river terrace was estimated at 4.8 Tg ± 1.5 Tg, and the total N pool of the floodplains was estimated at 7.7 Tg ± 3.6 Tg. Considering the projections for deepening of the seasonally thawed active layer up to 120 cm in the Lena River Delta region within the 21st century, these large carbon and nitrogen stocks could become increasingly available for decomposition and mineralization processes.

Modeling the Production, Decomposition, and Transport of Dissolved Organic Carbon in Boreal Soils

Soil Science ◽  
2010 ◽  
Vol 175 (5) ◽  
pp. 223-232 ◽  
Author(s):  
Zhaosheng Fan ◽  
Jason C. Neff ◽  
Kimberly P. Wickland
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Boreal Soils

scholarly journals Geochemistry of Coastal Permafrost and Erosion-Driven Organic Matter Fluxes to the Beaufort Sea Near Drew Point, Alaska

2021 ◽  
Vol 8 ◽  
Author(s):  
Emily M. Bristol ◽  
Craig T. Connolly ◽  
Thomas D. Lorenson ◽  
Bruce M. Richmond ◽  
Anastasia G. Ilgen ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Late Pleistocene ◽  
21St Century ◽  
Marine Sediments ◽  
Coastal Erosion ◽  
Beaufort Sea ◽  
The Arctic ◽  
The Holocene ◽  
Kuparuk River

Accelerating erosion of the Alaska Beaufort Sea coast is increasing inputs of organic matter from land to the Arctic Ocean, and improved estimates of organic matter stocks in eroding coastal permafrost are needed to assess their mobilization rates under contemporary conditions. We collected three permafrost cores (4.5–7.5 m long) along a geomorphic gradient near Drew Point, Alaska, where recent erosion rates average 17.2 m year−1. Down-core patterns indicate that organic-rich soils and lacustrine sediments (12–45% total organic carbon; TOC) in the active layer and upper permafrost accumulated during the Holocene. Deeper permafrost (below 3 m elevation) mainly consists of Late Pleistocene marine sediments with lower organic matter content (∼1% TOC), lower C:N ratios, and higher δ13C values. Radiocarbon-based estimates of organic carbon accumulation rates were 11.3 ± 3.6 g TOC m−2 year−1 during the Holocene and 0.5 ± 0.1 g TOC m−2 year−1 during the Late Pleistocene (12–38 kyr BP). Within relict marine sediments, porewater salinities increased with depth. Elevated salinity near sea level (∼20–37 in thawed samples) inhibited freezing despite year-round temperatures below 0°C. We used organic matter stock estimates from the cores in combination with remote sensing time-series data to estimate carbon fluxes for a 9 km stretch of coastline near Drew Point. Erosional fluxes of TOC averaged 1,369 kg C m−1 year−1 during the 21st century (2002–2018), nearly doubling the average flux of the previous half-century (1955–2002). Our estimate of the 21st century erosional TOC flux year−1 from this 9 km coastline (12,318 metric tons C year−1) is similar to the annual TOC flux from the Kuparuk River, which drains a 8,107 km2 area east of Drew Point and ranks as the third largest river on the North Slope of Alaska. Total nitrogen fluxes via coastal erosion at Drew Point were also quantified, and were similar to those from the Kuparuk River. This study emphasizes that coastal erosion represents a significant pathway for carbon and nitrogen trapped in permafrost to enter modern biogeochemical cycles, where it may fuel food webs and greenhouse gas emissions in the marine environment.

scholarly journals A geochemical study of marine sediments from the Mac. Robertson shelf, East Antarctica: initial results and palaeoenvironmental implications

1998 ◽  
Vol 27 ◽  
pp. 268-274 ◽  
Author(s):  
P. N. Sedwick ◽  
P.T. Harris ◽  
L. G. Robertson ◽  
G. M. Mcmurtry ◽  
M. D. Cremer ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Late Holocene ◽  
Sediment Accumulation ◽  
Transport Processes ◽  
East Antarctica ◽  
Outer Shelf ◽  
Geochemical Data ◽  
Accumulation Rates ◽  
Inner Shelf ◽  
The Holocene

Sediments from the Antarctic continental margin may provide detailed palaeoenvironmental records for Antarctic shelf waters during the late Quaternary. Here we present results from a palaeoenvironmental study of two sediment cores recovered from the continental shelf off Mac. Robertson Land, East Antarctica. These gravity cores were collected approximately 90 km apart from locations on the inner and outer shelf. Both cores are apparently undisturbed sequences of diatom ooze mixed with fine, quartz-rich sand. Core stratigraphies have been established from radiocarbon analyses of bulk organic carbon. Down-core geochemical determinations include the lithogenic components AÍ and Fe, biogenic components opal and organic carbon, and palaco-redox proxies Mn, Mo and U. We use the geochemical data to infer past variations in the deposition of biogenic and lithogenic materials, and the radiocarbon dates to estimate average sediment accumulation rates. The Holocene record of the outer-shelf core suggests three episodes of enhanced diatom export production at about 1.8, 3.8 and 5.5 ka BP, as well as less pronounced bloom episodes which occurred over a shorter period. Average sediment accumulation rates at this location range from 13.7 cm ka−1 in the late Pleistocene early Holocene to 82 cm ka−1 in the late Holocene, and suggest that the inferred episodes of enhanced biogenic production lasted 100-1000 years. in contrast, data for the inner-shelf core suggest that there has been a roughly constant proportion of biogenic and lithogenic material accumulating during the middle to late Holocene, with a greater proportion of biogenic material relative to the outer shelf. Notably, there is an approximately 7-fold increase in average sediment accumulation rate (from 24.5 to 179 cm ka−1) at this inner-shelf location between the middle and late Holocene, with roughly comparable increases in the mass accumulation rates of both biogenic and lithogenic material. This may represent changes in sediment transport processes, or reflect real increases in pelagic sedimentation in this region during the Holocene. Our results suggest quite different sedimentation regimes in these two shelf locations during the middle to late Holocene.

Changes of the forest-savanna boundary in Brazilian Amazonia during the Holocene revealed by stable isotope ratios of soil organic carbon

Oecologia ◽  
1996 ◽  
Vol 108 (4) ◽  
pp. 749-756 ◽  
Author(s):  
T. Desjardins ◽  
A. C. Filho ◽  
A. Mariotti ◽  
C. Girardin ◽  
A. Chauvel
Keyword(s):  
Stable Isotope ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
The Holocene ◽  
Brazilian Amazonia
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