Origins of Nepheloid Layers on Continental Slopes: Laboratory and Field Experimentation

2001 ◽  
Author(s):  
Richard W. Sternberg ◽  
Erika E. McPhee
Keyword(s):  
Continental Slopes ◽  
Field Experimentation

Controls on the evolution of submarine canyons in steep continental slopes: geomorphological insights from Palar Basin, southeastern margin of India

2021 ◽  
Vol 41 (1) ◽  
Author(s):  
S. Susanth ◽  
P. John Kurian ◽  
C. M. Bijesh ◽  
D. Twinkle ◽  
Abhishek Tyagi ◽  
...  
Keyword(s):  
Submarine Canyons ◽  
Continental Slopes ◽  
Southeastern Margin ◽  
Palar Basin

scholarly journals Can anaerobic oxidation of methane prevent seafloor gas escape in a warming climate?

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1541-1554 ◽  
Author(s):  
Christian Stranne ◽  
Matt O'Regan ◽  
Martin Jakobsson ◽  
Volker Brüchert ◽  
Marcelo Ketzer
Keyword(s):  
Climate Warming ◽  
Future Climate ◽  
Hydraulic Fractures ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Warming Scenario ◽  
Oxidation Of Methane ◽  
Warming Climate ◽  
Continental Slopes ◽  
Fully Coupled

Abstract. Assessments of future climate-warming-induced seafloor methane (CH4) release rarely include anaerobic oxidation of methane (AOM) within the sediments. Considering that more than 90 % of the CH4 produced in ocean sediments today is consumed by AOM, this may result in substantial overestimations of future seafloor CH4 release. Here, we integrate a fully coupled AOM module with a numerical hydrate model to investigate under what conditions rapid release of CH4 can bypass AOM and result in significant fluxes to the ocean and atmosphere. We run a number of different model simulations for different permeabilities and maximum AOM rates. In all simulations, a future climate warming scenario is simulated by imposing a linear seafloor temperature increase of 3 ∘C over the first 100 years. The results presented in this study should be seen as a first step towards understanding AOM dynamics in relation to climate change and hydrate dissociation. Although the model is somewhat poorly constrained, our results indicate that vertical CH4 migration through hydraulic fractures can result in low AOM efficiencies. Fracture flow is the predicted mode of methane transport under warming-induced dissociation of hydrates on upper continental slopes. Therefore, in a future climate warming scenario, AOM might not significantly reduce methane release from marine sediments.

Maintaining Continental Slopes

Science ◽  
2002 ◽  
Vol 296 (5568) ◽  
pp. 613d-613 ◽  
Keyword(s):  
Continental Slopes

Analysis of the Relationship Between Rail Seat Load Distribution and Rail Seat Deterioration in Concrete Crossties

2014 ◽  
Author(s):  
Matthew Greve ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Christopher P. L. Barkan ◽  
Jose Mediavilla ◽  
...  
Keyword(s):  
Load Distribution ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Past Research ◽  
Concrete Surface ◽  
Hydraulic Pressure ◽  
Valuable Insight ◽  
Increased Risk ◽  
Abrasive Erosion ◽  
Field Experimentation

One of the most common failure modes of concrete crossties in North America is the degradation of the concrete surface at the crosstie rail seat, also known as rail seat deterioration (RSD). Loss of material beneath the rail can lead to wide gauge, rail cant deficiency, and an increased risk of rail rollover. Previous research conducted at the University of Illinois at Urbana-Champaign (UIUC) has identified five primary failure mechanisms: abrasion, crushing, freeze-thaw damage, hydro-abrasive erosion, and hydraulic pressure cracking. The magnitude and distribution of load applied to the rail seat affects four of these five mechanisms; therefore, it is important to understand the characteristics of the rail seat load distribution to effectively address RSD. As part of a larger study funded by the Federal Railroad Administration (FRA) aimed at improving concrete crossties and fastening systems, researchers at UIUC are attempting to characterize the loading environment at the rail seat using matrix-based tactile surface sensors (MBTSS). This instrumentation technology has been implemented in both laboratory and field experimentation, and has provided valuable insight into the distribution of a single load over consecutive crossties. A review of past research into RSD characteristics and failure mechanisms has been conducted to integrate data from field experimentation with existing knowledge, to further explore the role of the rail seat load distribution on RSD. The knowledge gained from this experimentation will be integrated with associated research conducted at UIUC to form the framework for a mechanistic design approach for concrete crossties and fastening systems.

scholarly journals Dynamic effects of predators on cyclic voles: field experimentation and model extrapolation

2002 ◽  
Vol 269 (1495) ◽  
pp. 991-997 ◽  
Author(s):  
Erkki Korpimäki ◽  
Kai Norrdahl ◽  
Tero Klemola ◽  
Terje Pettersen ◽  
Nils Chr. Stenseth
Keyword(s):  
Dynamic Effects ◽  
Field Experimentation

Population genetics, phylogeography, and systematics of the thornyhead rockfishes (Sebastolobus) along the deep continental slopes of the North Pacific Ocean

2000 ◽  
Vol 57 (8) ◽  
pp. 1701-1717 ◽  
Author(s):  
Carol A Stepien ◽  
Alison K Dillon ◽  
Amy K Patterson
Keyword(s):  
Pacific Ocean ◽  
Phylogenetic Trees ◽  
Sequence Data ◽  
North Pacific Ocean ◽  
Geographic Distance ◽  
The North ◽  
Continental Slopes ◽  
Genetic Patterns ◽  
Northern Pacific ◽  
Shortspine Thornyhead

Population genetic, phylogeographic, and systematic relationships are elucidated among the three species comprising the thornyhead rockfish genus Sebastolobus (Teleostei: Scorpaenidae). Genetic variation among sampling sites representing their extensive ranges along the deep continental slopes of the northern Pacific Ocean is compared using sequence data from the left domain of the mtDNA control region. Comparisons are made among the shortspine thornyhead (S. alascanus) (from seven locations), the longspine thornyhead (S. altivelis) (from five sites), which are sympatric in the northeast, and the broadbanded thornyhead (S. macrochir) (a single site) from the northwest. Phylogenetic trees rooted to Sebastes show that S. macrochir is the sister taxon of S. alascanus and S. altivelis. Intraspecific genetic variability is appreciable, with most individuals having unique haplotypes. Gene flow is substantial among some locations and others diverged significantly. Genetic divergences among sampling sites for S. alascanus indicate an isolation by geographic distance pattern. Genetic divergences for S. altivelis are unrelated to the hypothesis of isolation by geographic distance and appear to be more consistent with the hypothesis of larval retention in currents and gyres. Differences in geographic genetic patterns between the species are attributed to life history differences in their relative mobilities as juveniles and adults.

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