scholarly journals Beaufort Sea coastal erosion, sediment flux, shoreline evolution, and the erosional shelf profile

1988 ◽  
Keyword(s):  
Coastal Erosion ◽  
Beaufort Sea ◽  
Sediment Flux ◽  
Shoreline Evolution

Mobilization of aged carbon via meltwater floods and coastal erosion in the Canadian Arctic during the last deglaciation

2021 ◽  
Author(s):  
Junjie Wu ◽  
Gesine Mollenhauer ◽  
Ruediger Stein ◽  
Jens Hefter ◽  
Kirsten Fahl ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Coastal Erosion ◽  
Drainage System ◽  
Beaufort Sea ◽  
Sediment Flux ◽  
Biological Degradation ◽  
Last Deglaciation ◽  
Marine Organic Matter ◽  
Ocean Carbon

<p>It is consensus that the deglacial changes in ocean carbon storage and circulation play a role in regulating atmospheric CO<sub>2</sub>. However, emerging evidence suggests that the rapid deglacial CO<sub>2</sub> rises can in part be attributed to large quantities of pre-aged carbon being released from degrading permafrost. In this study, we apply a radiocarbon approach on both terrestrial compounds (high molecular weight fatty acids; HWM-FA) and bulk organic carbon from a well-studied core ARA04C/37 from the Canadian Beaufort Sea. Based on our records, substantial amounts of ancient carbon were supplied from land to the ocean during the mid-late deglaciation (14.5-10 cal. kyr BP) by frequent high sediment flux events. Because the core location is strongly influenced by the Mackenzie River discharge, sediments only contain minor contributions from marine organic matter, allowing to consider mainly two terrestrial sources to explain the characteristics of bulk sedimentary organic matter. The terrestrial HMW-FA are taken to represent the biospheric carbon, and their age differences from the bulk organic carbon are explained by petrogenic carbon input. During the Younger Dryas, ice-sheet melting and meltwater outbursts enhanced petrogenic carbon contributions, suggesting a major source in the hinterland drainage system. During the rapid sea-level rise (meltwater pulses 1a and 1b), the very old organic carbon and comparable ages between biospheric carbon and bulk organic carbon indicate the occurrence of permafrost carbon remobilization primarily via coastal erosion while petrogenic carbon from the drainage system was found negligible. Remobilized ancient permafrost carbon is commonly regarded to be highly bioavailable, while petrogenic carbon is likely more recalcitrant to biological degradation. Our records thus suggest that the release of ancient carbon to the Beaufort Sea had the strongest impact on the atmospheric CO<sub>2</sub> level and contributed to its rapid increases during the B/A and Pre-Boreal when permafrost deposits along the coast were eroded.</p>

Empirical modelling of beach evolution: implementation of coupled cross-shore and longshore approaches

2020 ◽  
Author(s):  
Teddy Chataigner ◽  
Marissa Yates ◽  
Nicolas Le Dantec
Keyword(s):  
Morphological Evolution ◽  
Computational Cost ◽  
Sandy Beaches ◽  
Sediment Flux ◽  
Beach Profile ◽  
Change Models ◽  
Empirical Modelling ◽  
Spatial And Temporal Scales ◽  
Shoreline Evolution

<p>Understanding shoreline evolution, and in particular, the consequences of shoreline erosion is a<br>major societal concern that threatens to become even more important in the future with the impacts<br>of climate change. Thus, it is necessary to improve both knowledge of the dominant physical processes<br>controlling medium to long-term shoreline evolution and the capabilities of morphological evolution<br>models to simulate beach changes at these spatial and temporal scales.<br>Empirical models may be an ideal choice for modelling complex and dynamic environments such as<br>sandy beaches at large spatial (beach) and long temporal (years to decades) scales. They reproduce<br>the effects of the main morphodynamical processes with low computational cost and relatively high<br>accuracy, in particular when high quality, long-term data are available for calibration.<br>Here, to broaden its range of application, a cross-shore equilibrium model, which has demon-<br>strated its accuracy and efficiency in reproducing shoreline and intertidal beach profile changes at<br>several micro and macrotidal beaches, is extended to couple it with a longshore beach evolution<br>modelling approach. The selection of a particular longshore model (based on a one-line approach),<br>and its implementation and validation with benchmark test cases of shoreline evolution caused by<br>the effects of diffusion, high angle wave instabilities, and coastal structures are presented.<br>The new hybrid model is applied at Narrabeen beach to reproduce the long-term evolution of<br>beach contours near the shoreline. The model is calibrated and tested using the 40-year timeseries of<br>monthly subaerial beach profile surveys conducted along 5 cross-shore profiles along the 3.6km-long<br>Narrabeen-Collaroy embayment. The novelty of the current work is to focus on reproducing changes<br>at different altitudes, with the objective of assessing the cross-shore variability of the longshore<br>sediment flux, which is assumed constant in most one-line longshore transport models. The coupled<br>model performance is discussed, and the results are compared to existing studies that have simulated<br>shoreline evolution at Narrabeen using other morphological change models.</p>

A 14 - 0 ka record of trends and events of sea ice cover, primary production and freshwater discharge in the Beaufort Sea, Arctic Ocean

2020 ◽  
Author(s):  
Junjie Wu ◽  
Ruediger Stein ◽  
Kirsten Fahl ◽  
Nicole Syring ◽  
Jens Hefter ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Beaufort Sea ◽  
Ice Cover ◽  
Sediment Flux ◽  
The Arctic ◽  
Proxy Records ◽  
Ice Retreat ◽  
Sea Ice Retreat ◽  
Natural Climate

<p>The Arctic is changing rapidly, and one of the main and most obvious features is the drastic sea-ice retreat over the past few decades. Over such time scales, observations are deficient and not long enough for deciphering the processes controlling this accelerated sea-ice retreat. Thus, high-resolution, longer-term proxy records are needed for reconstruction of natural climate variability. In this context, we applied a biomarker approach on the well-dated sediment core ARA04C/37 recovered in the southern Beaufort Sea directly off the Mackenzie River, an area that is characterized by strong seasonal variability in sea-ice cover, primary productivity and terrigenous (riverine) input. Based on our biomarker records, the Beaufort Sea region was nearly ice-free in summer during the late Deglacial to early Holocene (14 to 8 ka). During the mid-late Holocene (8 to 0 ka), a seasonal sea-ice cover developed, coinciding with a drop in both terrigenous sediment flux and primary production. Supported by multiple proxy records, two major flood events characterized by prominent maxima in sediment flux occurred near 13 and 11 ka. The former is coincident with the Younger Dryas Cooling Event probably triggered by a  freshwater outburst from the Lake Agassiz. The origin of the second (younger) one might represent a second Mackenzie flood event, coinciding with meltwater pulse IB/post-glacial flooding of the shelf and related increased coastal erosion. Here, our interpretation remains a little bit speculative, and further research is needed and also in progress.</p>

scholarly journals Coastal vulnerability of a pinned, soft-cliff coastline, II: assessing the influence of sea walls on future morphology

2014 ◽  
Vol 2 (1) ◽  
pp. 233-242 ◽  
Author(s):  
A. Barkwith ◽  
M. D. Hurst ◽  
C. W. Thomas ◽  
M. A. Ellis ◽  
P. L. Limber ◽  
...  
Keyword(s):  
Coastal Erosion ◽  
Morphological Changes ◽  
Numerical Models ◽  
Field Research ◽  
Wave Climate ◽  
Sediment Flux ◽  
Climate Data ◽  
Coastal Morphology ◽  
Coastal Evolution ◽  
The Impact

Abstract. Coastal defences have long been employed to halt or slow coastal erosion, and their impact on local sediment flux and ecology has been studied in detail through field research and numerical simulation. The non-local impact of a modified sediment flux regime on mesoscale erosion and accretion has received less attention. Morphological changes at this scale due to defending structures can be difficult to quantify or identify with field data. Engineering-scale numerical models, often applied to assess the design of modern defences on local coastal erosion, tend not to cover large stretches of coast and are rarely applied to assess the impact of older structures. We extend previous work to explore the influences of sea walls on the evolution and morphological sensitivity of a pinned, soft-cliff, sandy coastline under a changing wave climate. The Holderness coast of East Yorkshire, UK, is used as a case study to explore model scenarios where the coast is both defended with major sea walls and allowed to evolve naturally were there are no sea defences. Using a mesoscale numerical coastal evolution model, observed wave-climate data are perturbed linearly to assess the sensitivity of the coastal morphology to changing wave climate for both the defended and undefended scenarios. Comparative analysis of the simulated output suggests that sea walls in the south of the region have a greater impact on sediment flux due to increased sediment availability along this part of the coast. Multiple defence structures, including those separated by several kilometres, were found to interact with each other, producing complex changes in coastal morphology under a changing wave climate. Although spatially and temporally heterogeneous, sea walls generally slowed coastal recession and accumulated sediment on their up-drift side.

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 Coastal erosion and mass wasting along the Canadian Beaufort Sea based on annual airborne LiDAR elevation data

Geomorphology ◽  
2017 ◽  
Vol 293 ◽  
pp. 331-346 ◽  
Author(s):  
Jaroslav Obu ◽  
Hugues Lantuit ◽  
Guido Grosse ◽  
Frank Günther ◽  
Torsten Sachs ◽  
...  
Keyword(s):  
Coastal Erosion ◽  
Beaufort Sea ◽  
Airborne Lidar ◽  
Mass Wasting ◽  
Elevation Data

scholarly journals Coastal Erosion of Permafrost Soils Along the Yukon Coastal Plain and Fluxes of Organic Carbon to the Canadian Beaufort Sea

2018 ◽  
Vol 123 (2) ◽  
pp. 406-422 ◽  
Author(s):  
Nicole J. Couture ◽  
Anna Irrgang ◽  
Wayne Pollard ◽  
Hugues Lantuit ◽  
Michael Fritz
Keyword(s):  
Organic Carbon ◽  
Coastal Plain ◽  
Coastal Erosion ◽  
Beaufort Sea ◽  
Permafrost Soils
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