Rapid Permafrost Carbon Degradation at the Land-Ocean Interface

NASA Astrophysics Data System (ADS)

Tanski, G.

2015-12-01

Climate change has a strong impact on permafrost coasts in the Arctic. With increasing air and water temperatures, the ice-rich unlithified permafrost coasts will thaw and erode at a greater pace. Organic carbon that has been stored for thousands of years is mobilized and degrades on its way to the ocean. The objective of this study is to investigate to what extent permafrost carbon degrades after thawing before it enters the ocean in a retrogressive thaw slump. A slump located on Herschel Island (Yukon Territory, Canada) was sampled systematically along transects from the permafrost headwall to the coastline. Concentrations of particulate and dissolved organic carbon (POC and DOC) as well as its stable carbon isotopes (δ13C-POC and δ13C-DOC) were measured and compared in frozen deposits and in thawed sediments. Ammonium, nitrite and nitrate were also analyzed in order to identify and understand the carbon metabolization mechanisms taking place during slump activity. Our results show that major portions of permafrost carbon are metabolized right after thawing. Ammonium concentrations are highest in areas where thawed permafrost material directly accumulates. We suggest that before entering the nearshore zone permafrost organic carbon and nitrogen is subject to major degradation and metabolization. This makes permafrost coasts and retrogressive thaw slumps degradation hotspots at the land-ocean-interface.

Progress report for project modeling Arctic barrier island-lagoon system response to projected Arctic warming

USGS Publications Warehouse

Erikson, Li H.; Gibbs, Ann E.; Richmond, Bruce M.; Storlazzi, Curt; B.M. Jones,

2012-01-01

Changes in Arctic coastal ecosystems in response to global warming may be some of the most severe on the planet. A better understanding and analysis of the rates at which these changes are expected to occur over the coming decades is crucial in order to delineate high-priority areas that are likely to be affected by climate changes. In this study we investigate the likelihood of changes to habitat-supporting barrier island – lagoon systems in response to projected changes in atmospheric and oceanographic forcing associated with Arctic warming. To better understand the relative importance of processes responsible for the current and future coastal landscape, key parameters related to increasing arctic temperatures are investigated and used to establish boundary conditions for models that simulate barrier island migration and inundation of deltaic deposits and low-lying tundra. The modeling effort investigates the dominance and relative importance of physical processes shaping the modern Arctic coastline as well as decadal responses due to projected conditions out to the year 2100.

Short and long-term thermo-erosion of ice-rich permafrost coasts in the Laptev Sea region

NASA Astrophysics Data System (ADS)

Günther, F.; Overduin, P. P.; Sandakov, A. V.; Grosse, G.; Grigoriev, M. N.

2013-02-01

Permafrost coasts in the Arctic are susceptible to a variety of changing environmental factors all of which currently point to increasing coastal erosion rates and mass fluxes of sediment and carbon to the shallow arctic shelf seas. Rapid erosion along high yedoma coasts composed of Ice Complex permafrost deposits creates impressive coastal ice cliffs and inspired research for designing and implementing change detection studies for a long time, but continuous quantitative monitoring and a qualitative inventory of coastal thermo-erosion for large coastline segments is still lacking. Our goal is to use observations of thermo-erosion along the mainland coast of the Laptev Sea in eastern Siberia to understand how erosion rates depend on coastal geomorphology and the relative contributions of waterline and atmospheric drivers to coastal thermo-erosion over the past 4 decades and in the past few years. We compared multitemporal sets of orthorectified satellite imagery from 1965 to 2011 for three segments of coastline with a length of 73 to 95 km each and analyzed thermo-denudation (TD) along cliff top and thermo-abrasion (TA) along cliff bottom for two nested time periods: long-term rates (the past 39-43 yr) and short term rates (the past 1-3 yr). The Normalized Difference Thermo-erosion Index (NDTI) was used as a proxy that qualitatively describes the relative proportions of TD and TA. Mean annual erosion rates at all three sites were higher in recent years (-5.3 ± 1.31 m a-1) than over the long term mean (-2.2 ± 0.13 m a-1). The Mamontov Klyk coast exhibit primarily spatial variations of thermo-erosion, while intrasite-specific variations were strongest at the Buor Khaya coast, where slowest long-term rates around -0.5 ± 0.08 m a-1 were observed. The Oyogos Yar coast showed continuously rapid erosion up to -6.5 ± 0.19 m a-1. In general, variable characteristics of coastal thermo-erosion were observed not only between study sites and over time, but also within single coastal transects along the cliff profile. Varying intensities of cliff bottom and top retreat are leading to diverse qualities of coastal erosion that have different impacts on coastal mass fluxes. The different extents of Ice Complex permafrost degradation within our study sites turned out to influence not only the degree of coupling between TD and TA, and the magnitude of effectively eroded volumes, but also the quantity of organic carbon released to the shallow Laptev Sea from coastal erosion, which ranged on a long-term from 88 ± 21.0 to 800 ± 61.1 t per km coastline per year and will correspond to considerably higher amounts, if recently observed more rapid coastal erosion rates prove to be persistent.

Panama City and Canal

NASA Image and Video Library

1994-09-30

STS068-237-099 (30 September-11 October 1994) --- This 70mm frame shows the Panama Canal (center, between the two dark green belts) the main ship way to travel from the Atlantic to the Pacific Ocean. Also seen is a great deal of detail in Panama City (left center, on the Pacific Ocean coastline). Geologists studying the photography returned by Shuttle astronauts feel this picture is the best ever of the city. Agricultural fields can be seen on the east side of Panama City and on both sides of the Pan American Highway (the straight thin line extending to the left). Sedimentation in the Chepo River (upper left) is thought to be due to eroded soil from the agricultural lands near the sea. This river is surrounded by swamps lying along the Pacific coastline.

Ocean Wave Energy Regimes of the Circumpolar Coastal Zones

NASA Astrophysics Data System (ADS)

Atkinson, D. E.

2004-12-01

Ocean wave activity is a major enviromental forcing agent of the ice-rich sediments that comprise large sections of the arctic coastal margins. While it is instructive to possess information about the wind regimes in these regions, direct application to geomorphological and engineering needs requires knowledge of the resultant wave-energy regimes. Wave energy information has been calculated at the regional scale using adjusted reanalysis model windfield data. Calculations at this scale are not designed to account for local-scale coastline/bathymetric irregularities and variability. Results will be presented for the circumpolar zones specified by the Arctic Coastal Dynamics Project.

The Race to Nourish: Exploring resource equity in a coupled human coastline model

NASA Astrophysics Data System (ADS)

Williams, Z. C.; McNamara, D.; Murray, A.; Smith, M.

2011-12-01

Many coastal communities are faced with eroding shorelines due to gradients in the alongshore transport of sediment and rising sea level. These communities often employ a beach nourishment mitigation strategy to counter erosion from natural forces. These nourishment activities provide economic benefits in the form of protection from storms and enhanced recreation on the stabilized beach. Previous work has shown that economically optimal nourishment decisions indicate that rising nourishment costs can lead to more frequent nourishment. Given that the cost of nourishing is likely to rise as offshore sediment borrow sites become more scarce, this suggests a positive feedback whereby nourishment that dwindles offshore borrow sites causes more frequent nourishment. We explore the dynamics of this feedback in a coupled economic-coastline model and how resulting long term shoreline and economic patterns respond to forcing changes in the form of increased sea level rise and changing storminess along both a straight shoreline and a cuspate Carolina like shoreline. The economic model utilizes myopic manager agents that inform a community of the optimal nourishment interval based on the current cost of sand and locally observed erosion rate since the last nourishment episode. Communities nourish independently but can affect the erosion rate of adjacent communities through alongshore sediment transport dynamics. The coastline model tracks large-scale coastline change via alongshore sediment transport calculations and erosion due to rising sea level. Model experiments show that when the economic model is coupled to a flat coastline, the feedback in sand cost leads to resource inequity as communities that become caught in the feedback nourish frequently while adjacent communities maintain coastline position by "free riding" on these neighbor towns. Model experiments also show that on cuspate coastlines, the emergent cuspate features enhance the cost feedback and create unequal resource distributions similar to flat coastlines but in locations pre-determined by large-scale patterns of erosion associated with the cuspate features. As wave climates change, communities that are already caught in a nourishment feedback, are not able to adjust their behavior to the new wave climate. This hysteresis effect in nourishment suggests the need for large-spatial-scale management of coastlines to achieve resource equity.

Life in a temperate Polar sea: a unique taphonomic window on the structure of a Late Cretaceous Arctic marine ecosystem

PubMed Central

Chin, Karen; Bloch, John; Sweet, Arthur; Tweet, Justin; Eberle, Jaelyn; Cumbaa, Stephen; Witkowski, Jakub; Harwood, David

2008-01-01

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75 Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input. PMID:18713718

Drawing the line on the sand

NASA Astrophysics Data System (ADS)

Ranasinghe, R.; Jongejan, R.; Wainwright, D.; Callaghan, D. P.

2016-02-01

Up to 70% of the world's sandy coastlines are eroding, resulting in gradual and continuous coastline recession. The rate of coastline recession is likely to increase due to the projected impacts of climate change on mean sea levels, offshore wave climate and storm surges. At the same time, rapid development in the world's coastal zones continues to increase potential damages, while often reducing the resilience of coastal systems. The risks associated with coastline recession are thus likely to increase over the coming decades, unless effective risk management plans are put in place. Land-use restrictions are a key component of coastal zone risk management plans. These involve the use of coastal setback lines which are mainly established by linearly adding the impacts of storms, recession due to sea level rise, and ambient long term trends in shoreline evolution. This approach does not differentiate between uncertainties that develop differently over time, nor takes into account the value and lifetime of property developments. Both shortcomings could entail considerable social cost. For balancing risk and reward, probabilistic estimates of coastline recession are a pre-requisite. Yet the presently adopted deterministic methods for establishing setback lines are unable to provide such estimates. Here, we present a quantitative risk analysis (QRA) model, underpinned by a multi-scale, physics based coastal recession model capable of providing time-dependent risk estimates. The modelling approach presented enables the determination of setback lines in terms of exceedance probabilities, a quantity that directly feeds into risk evaluations and economic optimizations. As a demonstration, the risk-informed approach is applied to Narrabeen beach, Sydney, Australia.

The joint Russia-US-Sweden studies in the East-Siberian Arctic Shelf (ESAS) during the last decade (1999-2009): an overview

NASA Astrophysics Data System (ADS)

Sergienko, Valentin; Shakhova, Natalia; Dudarev, Oleg; Gustafsson, Orjan; Anderson, Leif; Semiletov, Igor

2010-05-01

The Arctic Ocean is surrounded by permafrost, which is being degraded at an increasing rate under conditions of warming which are most pronounced in Siberia and Alaska . A major constraint on our ability to understand linkages between the Arctic Ocean and the global climate system is the scarcity of observational data in the Siberian Arctic marginal seas where major fresh water input and terrestrial CNP fluxes exist. The East-Siberian Sea has never been investigated by modern techniques despite the progress that has been made in new technologies useful for measuring ocean characteristics of interest. In this multi-year international project which joins scientists from 3 nations (Russia-USA-Sweden), and in cooperation with scientists from other countries (UK, Netherlands) we focus on he ESAS which is poorly explored areas located west from the U.S.-Russia boundary. In this report we overview the main field activities and present some results obtained during the last decade (1999-2009). Siberian freshwater discharge to the Arctic Ocean is expected to increase with increasing temperatures, potentially resulting in greater river export of old terrigenous organic carbon to the ocean. We suggest that rivers integrate variability in the components of the hydrometeorological regime, including soil condition, permafrost seasonal thaw, and thermokarst development, all the variables that determine atmospheric and ground water supply for the rivers and chemical weathering in their watershed.. It has been found that 1) carbon dioxide and methane fluxes are significant (and non-counted) components of the carbon cycling in the Arctic Ocean; 2) transport of eroded terrestrial material plays a major role in the accumulation of carbon in the ESAS (Dudarev et al., Gustafsson et al., Vonk et al., Sanchez-Garcia et al., Charkin et al., Semiletov et al., this session) ; 3) the seabed is a major CH4 source over the ESAS (N.Shakhova et al., this session); 3) eroded carbon is biodegradable (all reports, this session); 4) oxidation of eroded carbon onshore and offshore is a strong source of carbon dioxide (Piko et al. and Semiletov et al., this session). Thus studying carbon cycling in the East Siberian Arctic marginal seas has a high scientific priority in order to establish the carbon budget and evaluate the role of the Arctic region in global carbon cycling, especially in the coastal zone where the redistribution of carbon between terrestrial and marine environments occurs and the characteristics of carbon exchange with atmosphere are unknown. Initial scientific plan for the next decade is discussed. This study was supported by the Russian Foundation for Basic Research (since 1994), International (Soros) Scientific Foundation, ISF (1994-1995), Russian Government and ISF (1995), McArthur Foundation (2000-2001), FEBRAS/RAS (since 2003), IARC (since 2001), NSF (since 2003), NOAA (since 2005), SU (since 2007), and Wallenberg Foundation (since 2008).

Major coastal impact induced by a 1000-year storm event

PubMed Central

Fruergaard, Mikkel; Andersen, Thorbjørn J.; Johannessen, Peter N.; Nielsen, Lars H.; Pejrup, Morten

2013-01-01

Extreme storms and storm surges may induce major changes along sandy barrier coastlines, potentially causing substantial environmental and economic damage. We show that the most destructive storm (the 1634 AD storm) documented for the northern Wadden Sea within the last thousand years both caused permanent barrier breaching and initiated accumulation of up to several metres of marine sand. An aggradational storm shoal and a prograding shoreface sand unit having thicknesses of up to 8 m and 5 m respectively were deposited as a result of the storm and during the subsequent 30 to 40 years long healing phase, on the eroded shoreface. Our results demonstrate that millennial-scale storms can induce large-scale and long-term changes on barrier coastlines and shorefaces, and that coastal changes assumed to take place over centuries or even millennia may occur in association with and be triggered by a single extreme storm event.

Seasonal variation in the free-running period in two Talitrus saltator populations from Italian beaches differing in morphodynamics and human disturbance

NASA Astrophysics Data System (ADS)

Nardi, M.; Morgan, E.; Scapini, F.

2003-10-01

The sandhopper Talitrus saltator Montagu (Amphipoda) is a widespread species adapted to different changing environmental conditions and which typically shows a clear circadian rhythm of locomotor activity. The populations from two beaches on the western Italian coast differing in coastline dynamics (eroded versus dynamically stable) and human disturbance (inside a natural park versus freely used and cleaned for leisure) were studied to highlight intrapopulation variation in the endogenous locomotor rhythm. The activity of adult sandhoppers was studied under constant laboratory conditions within individual recording chambers. Variation of the free-running period was analysed at individual level within each population. Greater variability was found than previously reported for the circadian rhythm period of T. saltator, and seasonal variation was shown for the first time. Differences in the level of variation were correlated with coastline dynamics.

Sedimentation in the Lena river delta and adjacent part of the Laptev Sea

NASA Astrophysics Data System (ADS)

Charkin, A.; Dudarev, O.; Semiletov, I.; Vonk, J.; Sanchez-Garcia, L.; Gustafsson, Ö.; Andersson, P.; Shakhova, N.

2009-04-01

Any attempt to understand the effects of the Arctic Ocean on global change or the effect of global change on the Arctic Ocean requires a thorough understanding of coastal processes. The major transport of freshwater, dissolved and solid materials into the Arctic ocean is determined by riverine discharge and coastal erosion from Eurasia . The Lena River drains almost 3 mill. km2 of the vast Siberian hinterland (which is now under strong warming impact), and discharge up to 720 km3 per year, making it the second largest river draining into the Arctic Ocean. Thus, it is extremely important to perform a base-line study in the key area of the near-shore Arctic ocean which integrates Lena River discharge, which is a product o permafrost degradation in the Lena watershed, and off-shore export of eroded material, which is mostly induced by retreatment of the coastal ice-complex. Since 1999, the Buor-Khaya Gulf was chosen for detailed investigation by Laboratory of the Arctic Research (LAR) of the Pacific Oceanological Institute as a key area which accepts both eroded carbon and solid discharge from the Bykovsky and Bol'shay/Malaya Trofimovsky channels of the Lena delta. The intention of this report is to present a first comprehensive interpretation of the modern depositional environment in the Lena river delta and Buor-Khaya Gulf considering all the geochemical data obtained both in the International Siberian Shelf Study2008 (ISSS-08) and 11 previous summertime and wintertime LAR expeditions (1999-2007), accomplished in cooperation with the International Arctic Research Center of the University Alaska Fairbanks. Set of samples was studied in cooperation with the Stockholm University and Swedish Museum of Natural History. Detailed transects and maps of the particulate material distribution, particulate organic carbon (POC) and nitrogen (PON) as well as CN stable isotopes in both suspended particles and underlying surface sediment, and its sizing are discussed in connection with changing hydrometeorological conditions with a special emphasis on the area surrounding Muostakh Island, which exhibits rates of coastal erosion up to 15-20 m during couple summertime weeks.

U.S. Navy Marine Climatic Atlas of the World. Volume 6. Arctic Ocean

DTIC Science & Technology

1963-02-01

commonly used trade ch or closely parallel coastlines. difTerences will be noted between isopleth values graphs in the same area. Most discrepancies...95% H»«fil range e 1,500 Uf. otd ihe M% 84% range e 1,000 ( etf ) Mean and langei a’ height are omrtled «hen data loi o level OfB mining at

Hypsometry, volume and physiography of the Arctic Ocean and their paleoceanographic implications

NASA Astrophysics Data System (ADS)

Jakobsson, M.; Macnab, R.; Grantz, A.; Kristoffersen, Y.

2003-04-01

Recent analyses of the International Bathymetric Chart of the Arctic Ocean (IBCAO) grid model include: Hypsometry (the distribution of surface area at various depths); ocean volume distribution; and physiographic provinces [Jakobsson 2002; Jakobsson et al., in press]. The present paper summarizes the main results from these recent studies and expands on the paleoceanographic implications for the Arctic Ocean, which in this work is defined as the broad continental shelves of the Barents, Kara, Laptev, East Siberian and Chukchi Seas, the White Sea and the narrow continental shelves of the Beaufort Sea, the Arctic continental margins off the Canadian Arctic Archipelago and northern Greenland. This, the World's smallest ocean, is a virtually land-locked ocean that makes up merely 2.6 % of the area, and 1.0 % of the volume, of the entire World Ocean. The continental shelf area, from the coastline out to the shelf break, comprises as much as 52.9 % of the total area in the Arctic Ocean, which is significantly larger in comparison to the rest of the world oceans where the proportion of shelves, from the coastline out to the foot of the continental slope, only ranges between about 9.1 % and 17.7 %. In Jakobsson [2002], the seafloor area and water volume were calculated for different depths starting from the present sea level and progressing in increments of 10 m to a depth of 500 m, and in increments of 50 m from 550 m down to the deepest depth within each of the analyzed Arctic Ocean seas. Hypsometric curves expressed as simple histograms of the frequencies in different depth bins were presented, along with depth plotted against cumulative area for each of the analyzed seas. The derived hypsometric curves show that most of the Arctic Ocean shelf seas besides the Barents Sea, Beaufort Sea and the shelf off northern Greenland have a similar shape with the largest seafloor area between 0 and 50 m. The East Siberian and Laptev seas, in particular, show area distributions concentrated in this shallow depth range, and together with the Chukchi Sea they form a large flat shallow shelf province comprising as much as 22 % of the entire Arctic Ocean area, but only 1 % of the volume. Given this vast shelf area it may be speculated that the Arctic Ocean circulation is more sensitive to eustatic sea level changes compared to the other world oceans. For example, during the LGM when the sea level was ca 120 m lower than today most, if not all, of the Arctic Ocean shelf region could not play a role in the ocean circulation. Besides being the world's smallest ocean with the by far largest shelf area in proportion to its size, the Arctic Ocean is unique in terms of its physiographic setting. The Fram Strait is the only real break in the barrier of vast continental shelves enclosing the Arctic Ocean. The second largest physiographic province after the continental shelves consists of ridges, which is in contrast to the rest of the World's oceans where abyssal plains dominate. As much as 15.8 % of the area is underlain by ridges indicating the profound effect they have on ocean circulation. Jakobsson, M., Grantz, A., Kristoffersen, Y., and Macnab, R., in press, Physiographic Provinces of the Arctic Ocean, GSA Bulletin. Jakobsson, M., 2002, Hypsometry and volume of the Arctic Ocean and its constituent’s seas, Geochemistry Geophysics Geosystems, v. 3, no. 2.

The Relationship Between Environment and Nutritional Condition of Arctic Forage Fish

NASA Astrophysics Data System (ADS)

Vollenweider, J.; Heintz, R.; Callahan, M.; Barton, M. B.; Sousa, L.; Danielson, S. L.; Meuter, F.; Moran, J.; Boswell, K. M.

2016-02-01

We describe how marine environmental conditions influence the body condition of forage fish in the Alaskan Arctic. Body condition of fish is a sensitive predictor of fish productivity, with consequences particularly for juvenile survival as well as adult reproduction. For example, body condition of juvenile walleye pollock (Theragra chalcogramma) in the Bering Sea is a significant predictor of survival to recruitment, and a better index than sheer abundance of juveniles. Body condition of fish generally varies with interannual fluctuations in oceanographic conditions such as temperature and wind mixing, which may have cascading effects on food quality and availability, and ultimately fish survival. We use these underlying principles to examine how interannual and spatial variation in environmental conditions affect fish condition of various Arctic species. Specifically, we measured the energy content of some of the most abundant Arctic forage species including Arctic cod (Boreogadus saida), capelin (Mallotus villosus), fourhorn sculpin (Myoxocephalus quadricornis), and saffron cod (Eleginus gracilis) over multiple years and habitats. Fish were sampled from multiple projects (ACES, SHELFZ, Arctic Eis) from three physically distinct waterbodies: the Chukchi and Beaufort Seas, and Elson Lagoon, an extensive, shallow estuary characteristic of the Arctic coastline. Fish condition of the various species responded differently to interannual changes and amongst water bodies. For example, Arctic Cod had energy density in 2014 compared with other years while fourhorn sculpin were unperturbed. These findings will help identify favorable habitats for Arctic species, identify locations and condition contributing the most to fish productivity, and will help predict how Arctic fish and their predators may fare in the face of climate change.

Quantifying model uncertainty in seasonal Arctic sea-ice forecasts

NASA Astrophysics Data System (ADS)

Blanchard-Wrigglesworth, Edward; Barthélemy, Antoine; Chevallier, Matthieu; Cullather, Richard; Fučkar, Neven; Massonnet, François; Posey, Pamela; Wang, Wanqiu; Zhang, Jinlun; Ardilouze, Constantin; Bitz, Cecilia; Vernieres, Guillaume; Wallcraft, Alan; Wang, Muyin

2017-04-01

Dynamical model forecasts in the Sea Ice Outlook (SIO) of September Arctic sea-ice extent over the last decade have shown lower skill than that found in both idealized model experiments and hindcasts of previous decades. Additionally, it is unclear how different model physics, initial conditions or post-processing techniques contribute to SIO forecast uncertainty. In this work, we have produced a seasonal forecast of 2015 Arctic summer sea ice using SIO dynamical models initialized with identical sea-ice thickness in the central Arctic. Our goals are to calculate the relative contribution of model uncertainty and irreducible error growth to forecast uncertainty and assess the importance of post-processing, and to contrast pan-Arctic forecast uncertainty with regional forecast uncertainty. We find that prior to forecast post-processing, model uncertainty is the main contributor to forecast uncertainty, whereas after forecast post-processing forecast uncertainty is reduced overall, model uncertainty is reduced by an order of magnitude, and irreducible error growth becomes the main contributor to forecast uncertainty. While all models generally agree in their post-processed forecasts of September sea-ice volume and extent, this is not the case for sea-ice concentration. Additionally, forecast uncertainty of sea-ice thickness grows at a much higher rate along Arctic coastlines relative to the central Arctic ocean. Potential ways of offering spatial forecast information based on the timescale over which the forecast signal beats the noise are also explored.

Late summer and fall wave climate in the Beaufort and Chukchi Seas, 2000-2014

NASA Astrophysics Data System (ADS)

Fan, Y.; Rogers, W.; Thomson, J.; Stopa, J.

2016-02-01

Jim Thomson, Applied Physics Laboratory, University of Washington, Seattle, WA According to IPCC, "warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world." Some regions within the Arctic have warmed even more rapidly, with Alaska and western Canada's temperature rising by 3 to 4 °C (5.40 to 7.20 °F). Arctic ice is getting thinner, melting and rupturing. The polar ice cap as a whole is shrinking. Images from NASA satellites show that the area of permanent ice cover is contracting at a rate of 9 percent each decade. If this trend continues, summers in the Arctic could become ice-free by the end of the century. Arctic storms thus have the potential to create large waves in the region. Ocean waves can also penetrate remarkable distances into ice fields and impact sea-ice thermodynamics by breaking up ice floes and accelerating ice melting during the summer (Asplin et al 2012); or influencing sea-ice growth and hence the morphology of the mature ice sheet during the winter (Lange et al 1989). Waves breaking on the shore could also affect the coastlines, where melting permafrost is already making shores more vulnerable to erosion. Preliminary wave model results from four selected years suggests that the sea state of the Beaufort and Chukchi seas is controlled by the wind forcing and the amount of ice-free water available to generate surface waves. In particular, larger waves are more common in years with low or late sea ice cover. Trends in amount of wave energy impinging on the ice edge, however, are inconclusive. To better understand the potential effect of surface wave on the advance/retreat of ice edges and the coastlines. 15 years (2000 to 2014) of surface wave simulations in the Arctic Ocean using WAVEWATCH III will be conducted. Wind and ice forcing are obtained from the ERA-interim global reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). Wave energy flux arriving at the ice edges and land boundaries will be analyzed and histograms and fitted Weibull probability distribution functions will used to identify similarities and differences during the 15 year period. The potential effect of surface waves on ice advance/retreat and land erosion will be explored and discussed.

Multi-model seasonal forecast of Arctic sea-ice: forecast uncertainty at pan-Arctic and regional scales

NASA Astrophysics Data System (ADS)

Blanchard-Wrigglesworth, E.; Barthélemy, A.; Chevallier, M.; Cullather, R.; Fučkar, N.; Massonnet, F.; Posey, P.; Wang, W.; Zhang, J.; Ardilouze, C.; Bitz, C. M.; Vernieres, G.; Wallcraft, A.; Wang, M.

2017-08-01

Dynamical model forecasts in the Sea Ice Outlook (SIO) of September Arctic sea-ice extent over the last decade have shown lower skill than that found in both idealized model experiments and hindcasts of previous decades. Additionally, it is unclear how different model physics, initial conditions or forecast post-processing (bias correction) techniques contribute to SIO forecast uncertainty. In this work, we have produced a seasonal forecast of 2015 Arctic summer sea ice using SIO dynamical models initialized with identical sea-ice thickness in the central Arctic. Our goals are to calculate the relative contribution of model uncertainty and irreducible error growth to forecast uncertainty and assess the importance of post-processing, and to contrast pan-Arctic forecast uncertainty with regional forecast uncertainty. We find that prior to forecast post-processing, model uncertainty is the main contributor to forecast uncertainty, whereas after forecast post-processing forecast uncertainty is reduced overall, model uncertainty is reduced by an order of magnitude, and irreducible error growth becomes the main contributor to forecast uncertainty. While all models generally agree in their post-processed forecasts of September sea-ice volume and extent, this is not the case for sea-ice concentration. Additionally, forecast uncertainty of sea-ice thickness grows at a much higher rate along Arctic coastlines relative to the central Arctic ocean. Potential ways of offering spatial forecast information based on the timescale over which the forecast signal beats the noise are also explored.

Cryogenic formation of brine and sedimentary mirabilite in submergent coastal lake basins, Canadian Arctic

NASA Astrophysics Data System (ADS)

Grasby, Stephen E.; Rod Smith, I.; Bell, Trevor; Forbes, Donald L.

2013-06-01

Two informally named basins (Mirabilite Basins 1 and 2) along a submergent coastline on Banks Island, Canadian Arctic Archipelago, host up to 1 m-thick accumulations of mirabilite (Na2SO4·10H2O) underlying stratified water bodies with basal anoxic brines. Unlike isostatically uplifting coastlines that trap seawater in coastal basins, these basins formed from freshwater lakes that were transgressed by seawater. The depth of the sill that separates the basins from the sea is shallow (1.15 m), such that seasonal sea ice formation down to 1.6 m isolates the basins from open water exchange through the winter. Freezing of seawater excludes salts, generating dense brines that sink to the basin bottom. Progressive freezing increases salinity of residual brines to the point of mirabilite saturation, and as a result sedimentary deposits of mirabilite accumulate on the basin floors. Brine formation also leads to density stratification and bottom water anoxia. We propose a model whereby summer melt of the ice cover forms a temporary freshwater lens, and rather than mixing with the underlying brines, it is exchanged with seawater once the ice plug that separates the basins from the open sea melts. This permits progressive brine development and density stratification within the basins.

Numerical Modeling of Large-Scale Rocky Coastline Evolution

NASA Astrophysics Data System (ADS)

Limber, P.; Murray, A. B.; Littlewood, R.; Valvo, L.

2008-12-01

Seventy-five percent of the world's ocean coastline is rocky. On large scales (i.e. greater than a kilometer), many intertwined processes drive rocky coastline evolution, including coastal erosion and sediment transport, tectonics, antecedent topography, and variations in sea cliff lithology. In areas such as California, an additional aspect of rocky coastline evolution involves submarine canyons that cut across the continental shelf and extend into the nearshore zone. These types of canyons intercept alongshore sediment transport and flush sand to abyssal depths during periodic turbidity currents, thereby delineating coastal sediment transport pathways and affecting shoreline evolution over large spatial and time scales. How tectonic, sediment transport, and canyon processes interact with inherited topographic and lithologic settings to shape rocky coastlines remains an unanswered, and largely unexplored, question. We will present numerical model results of rocky coastline evolution that starts with an immature fractal coastline. The initial shape is modified by headland erosion, wave-driven alongshore sediment transport, and submarine canyon placement. Our previous model results have shown that, as expected, an initial sediment-free irregularly shaped rocky coastline with homogeneous lithology will undergo smoothing in response to wave attack; headlands erode and mobile sediment is swept into bays, forming isolated pocket beaches. As this diffusive process continues, pocket beaches coalesce, and a continuous sediment transport pathway results. However, when a randomly placed submarine canyon is introduced to the system as a sediment sink, the end results are wholly different: sediment cover is reduced, which in turn increases weathering and erosion rates and causes the entire shoreline to move landward more rapidly. The canyon's alongshore position also affects coastline morphology. When placed offshore of a headland, the submarine canyon captures local sediment, increases weathering and erosion around the headland, and eventually changes the headland into an embayment! Improvements to our modeling approach include refining the initial conditions. To create a fractal, immature rocky coastline, self-similar river networks with random side branches were drawn on the shoreline domain. River networks and side branches were scaled according to Horton's law and Tokunaga statistics, respectively, and each river pathway was assigned a simple exponential longitudinal profile. Topography was generated around the river networks to create drainage basins and, on a larger scale, represent a mountainous, fluvially-sculpted landscape. The resultant morphology was then flooded to a given elevation, leaving a fractal rocky coastline. In addition to the simulated terrain, actual digital elevation models will also be used to derive the initial conditions. Elevation data from different mountainous geomorphic settings such as the decaying Appalachian Mountains or actively uplifting Sierra Nevada can be effectively flooded to a given sea level, resulting in a fractal and immature coastline that can be input to the numerical model. This approach will offer insight into how rocky coastlines in different geomorphic settings evolve, and provide a useful complement to results using the simulated terrain.

Patterns and Controls of Erosion along the Elson Lagoon Coastline, Barrow, Alaska (2003-2016)

NASA Astrophysics Data System (ADS)

Tweedie, C. E.; Escarzaga, S. M.; Cody, R. P.; Manley, W. F.; Gaylord, A. G.; Aiken, Q.; Lopez, A. F.; Aguirre, A.; George, C.; Nelson, L.; Brown, J.

2016-12-01

With arctic warming and the combined effect of decreased summer sea ice extent, longer fetch for wave propagation, warmer sea surface and ground temperature, and longer periods of open water; the propensity for increased arctic coastal erosion rates and land-ocean sediment inputs to increase has been recognized for some time. In this study, we report on coastal erosion trends along a 11km stretch of coastline adjacent to the Barrow Environmental Observatory (BEO) where the position of the 2-4 meter high coastal bluff has been monitored annually with survey grade differential GPS (dGPS). Modern and historic erosion trends can be viewed through interactive web mapping applications at http://barrowmapped.org/. Rates of aerial and volumetric erosion losses averaged 0.7-2.8 meters and 0.8-3.5 cubic meters per meter of coast per year from 2003-2015 for each of the four coastal sections monitored. These losses equate to losses to the atmosphere and/or inputs to lagoon waters 53-220kgC per meter of coast per year. Such aerial losses are lower than from other areas of the Beaufort Sea coast that lack protective barrier islands, but 25-30% higher than historic decadal-scale change rates estimated for this section of coastline. However, regression analyses indicate no significant change to the rate of erosion during the past 13 years. Historic hotspots of erosion remained modern hotspots of erosion, and increases in modern erosion rates were greatest for sections of coast where historically high rates of erosion have been recorded. Regionally, the Elson Lagoon study area shows some of the highest rates of erosion for the Barrow Peninsula, which are generally 2-3 times mean annual erosion rates recorded for the Chukchi Sea Coastline near Barrow. Regression tree analysis used to isolate the relative importance of different biophysical controls of erosion differ between analyses run for aerial and volumetric losses along the Elson Lagoon Coast. These analyses also highlight key differences in controls between sampling periods with high/low wind-wave activity. In particular, analyses show the important influence of wave energy, land cover type, and landscape geomorphic history on modern coastal erosion dynamics.

Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean

NASA Astrophysics Data System (ADS)

Ramage, Justine L.; Irrgang, Anna M.; Morgenstern, Anne; Lantuit, Hugues

2018-03-01

Retrogressive thaw slumps (RTSs) are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC) budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1) describe the evolution of RTSs between 1952 and 2011; (2) calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC) and dissolved organic carbon (DOC); and (3) estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high-resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73 % increase in the number of RTSs and 14 % areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6×106 m3 of material, 53 % of which was ice, and mobilized 145.9×106 kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6×103 m3 yr-1 of material, adding 0.6 % to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.

National Assessment of Shoreline Change; historical shoreline change along the New England and Mid-Atlantic coasts

USGS Publications Warehouse

Hapke, Cheryl J.; Himmelstoss, Emily A.; Kratzmann, Meredith G.; List, Jeffrey H.; Thieler, E. Robert

2011-01-01

Beach erosion is a chronic problem along many open-ocean shores of the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of shoreline movement that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey (USGS) is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard, repeatable methods for mapping and analyzing shoreline movement so that periodic, systematic, internally consistent updates regarding coastal erosion and land loss can be made nationally. In the case of this study, the shoreline is the interpreted boundary between the ocean water surface and the sandy beach. This report on the New England and Mid-Atlantic coasts is the fifth in a series of reports on historical shoreline change. Previous investigations include analyses and descriptive reports of the Gulf of Mexico, the Southeast Atlantic, and, for California, the sandy shoreline and the coastal cliffs. The rates of change presented in this report represent conditions up to the date of the most recent shoreline data and therefore are not intended for predicting future shoreline positions or rates of change. Because of the geomorphology of the New England and Mid-Atlantic (rocky coastlines, large embayments and beaches) as well as data gaps in some areas, this report presents beach erosion rates for 78 percent of the 1,360 kilometers of the New England and Mid-Atlantic coasts. The New England and Mid-Atlantic shores were subdivided into a total of 10 analysis regions for the purpose of reporting regional trends in shoreline change rates. The average rate of long-term shoreline change for the New England and Mid-Atlantic coasts was -0.5 meters per year with an uncertainty in the long-term trend of plus or minus 0.09 meters per year. The rate is based on shoreline change rates averaged from 21,184 individual transects, of which 68 percent were eroding. In both the long and short term, the average rates of shoreline change for New England and the Mid-Atlantic were erosional. Long-term erosion rates were generally lower in New England than in the Mid-Atlantic. This is a function of the dominant coastal geomorphology; New England has a greater percentage of shore types that tend to erode more slowly (rocky coasts, pocket beaches, and mainland beaches), whereas the Mid-Atlantic is dominated by more vulnerable barrier islands and dynamic spit/inlet environments. However, the percentage of coastline eroding was higher in New England than in the Mid-Atlantic, highlighting that although rates of shoreline erosion may not be extreme, coastal erosion is still widespread along this region of the U.S. coastline. The average rate of short-term shoreline change for the New England and Mid-Atlantic coasts was also erosional but the rate of erosion decreased in comparison to long-term rates. The net short-term rate as averaged along 17,045 transects was -0.3 meters per year. Uncertainties for these rates range from 0.06 to 0.1 meters per year depending on the data sources used in the rate calculations. Of transects used to measure short-term change, 60 percent were erosional, as compared to 65 percent of coast eroding in the long term. The slight decrease (5 percent) in the amount of coastline eroding may be related to an increase in the frequency and extent of nourishment programs and (or) the effects of hardened structures during the more recent time period. The most stable (lower rates of erosion) beaches were more commonly found in New England. Despite an overall lowering of the average rates of erosion from long-term to short-term, the amount

Self-stabilized Fractality of Sea-coasts Through Damped Erosion

NASA Astrophysics Data System (ADS)

Sapoval, B.; Baldassari, A.; Gabrielli, A.

2004-05-01

Coastline morphology is of current interest in geophysical research and coastline erosion has important economic consequences. At the same time, although the geometry of seacoasts is often used as an introductory archetype of fractal morphology in nature there has been no explanation about which physical mechanism could justify that empirical observation. The present work propose a minimal, but robust, model of evolution of rocky coasts towards fractality. The model describes how a stationary fractal geometry arises spontaneously from the mutual self-stabilization of a rocky coast morphology and sea eroding power. If, on one hand, erosion generally increases the geometrical irregularity of the coast, on the other hand this increase creates a stronger damping of the sea and a consequent diminution of its eroding power. The increased damping argument relies on the studies of fractal acoustical cavities, which have shown that viscous damping is augmented on a longer, irregular, surface. A minimal two-dimensional model of erosion is introduced which leads to the through a complex dynamics of the earth-sea interface, to the appearance of a stationary fractal seacoast with dimension close to 4/3. Fractal geometry plays here the role of a morphological attractor directly related to percolation geometry. The model reproduces at least qualitatively some of the features of real coasts using only simple ingredients: the randomness of the lithology and the decrease of the erosion power of the sea. B. Sapoval, Fractals (Aditech, Paris, 1989). B. Sapoval, O. Haeberlé, and S.Russ, J. Acoust. Soc. Am., 2014 (1997). B. Hébert B., B. Sapoval, and S.Russ, J. Acoust. Soc. Am., 1567 (1999).

Soft-Cliff Retreat, Self-Organized Critical Phenomena in the Limit of Predictability?

NASA Astrophysics Data System (ADS)

Paredes, Carlos; Godoy, Clara; Castedo, Ricardo

2015-03-01

The coastal erosion along the world's coastlines is a natural process that occurs through the actions of marine and subaerial physico-chemical phenomena, waves, tides, and currents. The development of cliff erosion predictive models is limited due to the complex interactions between environmental processes and material properties over a wide range of temporal and spatial scales. As a result of this erosive action, gravity driven mass movements occur and the coastline moves inland. Like other studied earth natural and synthetically modelled phenomena characterized as self-organized critical (SOC), the recession of the cliff has a seemingly random, sporadic behavior, with a wide range of yearly recession rate values probabilistically distributed by a power-law. Usually, SOC systems are defined by a number of scaling features in the size distribution of its parameters and on its spatial and/or temporal pattern. Particularly, some previous studies of derived parameters from slope movements catalogues, have allowed detecting certain SOC features in this phenomenon, which also shares the recession of cliffs. Due to the complexity of the phenomenon and, as for other natural processes, there is no definitive model of recession of coastal cliffs. In this work, various analysis techniques have been applied to identify SOC features in the distribution and pattern to a particular case: the Holderness shoreline. This coast is a great case study to use when examining coastal processes and the structures associated with them. It is one of World's fastest eroding coastlines (2 m/yr in average, max observed 22 m/yr). Cliffs, ranging from 2 m up to 35 m in height, and made up of glacial tills, mainly compose this coast. It is this soft boulder clay that is being rapidly eroded and where coastline recession measurements have been recorded by the Cliff Erosion Monitoring Program (East Riding of Yorkshire Council, UK). The original database has been filtered by grouping contiguous sections, with similar geomorphological and dynamic features, to configure a complete and suitable catalogue of yearly recession rates (in m/yr) to analyze. Results show SOC fingerprint characteristics in the limited range scaling of the probability distribution function, in the variographic analysis and in the zero-mean Gaussian distribution of the Fourier coefficients. Therefore it cannot be neglected the possibility that Holderness cliffs behave as a SOC system. According to the discussed results, predictability possibilities of sea-cliff recession phenomena have been concluded.

Modern erosion rates and loss of coastal features and sites, Beaufort Sea coastline, Alaska

USGS Publications Warehouse

Jones, Benjamin M.; Hinkel, Kenneth M.; Arp, C.D.; Eisner, Wendy R.

2008-01-01

This study presents modern erosion rate measurements based upon vertical aerial photography captured in 1955, 1979, and 2002 for a 100 km segment of the Beaufort Sea coastline. Annual erosion rates from 1955 to 2002 averaged 5.6 m a-1. However, mean erosion rates increased from 5.0 m a-1 in 1955-79 to 6.2 m a-1 in 1979-2002. Furthermore, from the first period to the second, erosion rates increased at 60% (598) of the 992 sites analyzed, decreased at 31% (307), and changed less than ?? 30 cm at 9% (87). Historical observations and quantitative studies over the past 175 years allowed us to place our erosion rate measurements into a longer-term context. Several of the coastal features along this stretch of coastline received Western place names during the Dease and Simpson expedition in 1837, and the majority of those features had been lost by the early 1900s as a result of coastline erosion, suggesting that erosion has been active over at least the historical record. Incorporation of historical and modern observations also allowed us to detect the loss of both cultural and historical sites and modern infrastructure. U.S. Geological Survey topographic maps reveal a number of known cultural and historical sites, as well as sites with modern infrastructure constructed as recently as the 1950s, that had disappeared by the early 2000s as a result of coastal erosion. We were also able to identify sites that are currently being threatened by an encroaching coastline. Our modern erosion rate measurements can potentially be used to predict when a historical site or modern infrastructure will be affected if such erosion rates persist. ?? The Arctic Institute of North America.

Contemporary Arctic Sea Level

NASA Astrophysics Data System (ADS)

Cazenave, A. A.

2017-12-01

During recent decades, the Arctic region has warmed at a rate about twice the rest of the globe. Sea ice melting is increasing and the Greenland ice sheet is losing mass at an accelerated rate. Arctic warming, decrease in the sea ice cover and fresh water input to the Arctic ocean may eventually impact the Arctic sea level. In this presentation, we review our current knowledge of contemporary Arctic sea level changes. Until the beginning of the 1990s, Arctic sea level variations were essentially deduced from tide gauges located along the Russian and Norwegian coastlines. Since then, high inclination satellite altimetry missions have allowed measuring sea level over a large portion of the Arctic Ocean (up to 80 degree north). Measuring sea level in the Arctic by satellite altimetry is challenging because the presence of sea ice cover limits the full capacity of this technique. However adapted processing of raw altimetric measurements significantly increases the number of valid data, hence the data coverage, from which regional sea level variations can be extracted. Over the altimetry era, positive trend patterns are observed over the Beaufort Gyre and along the east coast of Greenland, while negative trends are reported along the Siberian shelf. On average over the Arctic region covered by satellite altimetry, the rate of sea level rise since 1992 is slightly less than the global mea sea level rate (of about 3 mm per year). On the other hand, the interannual variability is quite significant. Space gravimetry data from the GRACE mission and ocean reanalyses provide information on the mass and steric contributions to sea level, hence on the sea level budget. Budget studies show that regional sea level trends over the Beaufort Gyre and along the eastern coast of Greenland, are essentially due to salinity changes. However, in terms of regional average, the net steric component contributes little to the observed sea level trend. The sea level budget in the Arctic indicates a dominant mass contribution, especially in the Greenland, Norwegian, and Barents Seas sector.

ArcticDEM Year 3; Improving Coverage, Repetition and Resolution

NASA Astrophysics Data System (ADS)

Morin, P. J.; Porter, C. C.; Cloutier, M.; Howat, I.; Noh, M. J.; Willis, M. J.; Candela, S. G.; Bauer, G.; Kramer, W.; Bates, B.; Williamson, C.

2017-12-01

Surface topography is among the most fundamental data sets for geosciences, essential for disciplines ranging from glaciology to geodynamics. The ArcticDEM project is using sub-meter, commercial imagery licensed by the National Geospatial-Intelligence Agency, petascale computing, and open source photogrammetry software to produce a time-tagged 2m posting elevation model and a 5m posting mosaic of the entire Arctic region. As ArcticDEM enters its third year, the region has gone from having some of the sparsest and poorest elevation data to some of the most precise and complete data of any region on the globe. To date, we have produced and released over 80,000,000 km2 as 57,000 - 2m posting, time-stamped DEMs. The Arctic, on average, is covered four times though there are hotspots with more than 100 DEMs. In addition, the version 1 release includes a 5m posting mosaic covering the entire 20,000,000 km2 region. All products are publically available through arctidem.org, ESRI web services, and a web viewer. The final year of the project will consist of a complete refiltering of clouds/water and re-mosaicing of all elevation data. Since inception of the project, post-processing techniques have improved significantly, resulting in fewer voids, better registration, sharper coastlines, and fewer inaccuracies due to clouds. All ArcticDEM data will be released in 2018. Data, documentation, web services and web viewer are available at arcticdem.org

Coastal sea-ice processes in Alaska and their relevance for sediment dynamics and coastal retreat (Invited)

NASA Astrophysics Data System (ADS)

Eicken, H.; Kapsch, M.; Johnson, M. A.; Weyapuk, W. U., Jr.

2009-12-01

Sea ice plays an important, complicated role in Arctic coastal sediment dynamics. It helps protect the shoreline from wave action and constrains coastal permafrost thaw; at the same time, sea ice is a highly effective sediment erosion and transport agent. For the coastline of (sub-)Arctic Alaska we have examined key processes that govern the role of sea ice as a geologic agent. Based on passive microwave satellite data for the time period 1979 to 2008 and augmented by field measurements and observations conducted by local sea-ice experts in coastal communities from 2006 onwards, we determined the onset of coastal ice spring break-up and fall freeze-up. These two events define the start and end of the open-water season during which the coast is rendered most vulnerable to thermal and dynamic processes promoting erosion. Satellite data show significant trends toward later fall freeze-up in many locations and moreover provide a picture of the statistical significance and variability of such trends in great spatio-temporal detail. Coastal ice observations suggest that important sea-ice processes (such as formation of ice berms) that precede freeze-up as detected by passive microwave data need to be taken into consideration in evaluating the vulnerability of the coastline and the specific threat of individual storms. Field observations, satellite data and local knowledge also highlight the substantial change in winter sea-ice regimes over the past two decades, with a much more mobile ice cover enhancing winter sediment transport. Ultimately, the shorter sea-ice season and the greater mobility and the lack of stability of winter coastal sea ice work in concert to increase the vulnerability of the coastline to erosion and flooding. At the same time, these changes provide a mechanism for effective redistribution and cross-shelf transport of sediments that prepares the stage for further erosive action in subsequent seasons.

Late Wisconsinan glaciation and postglacial relative sea-level change on western Banks Island, Canadian Arctic Archipelago

NASA Astrophysics Data System (ADS)

Lakeman, Thomas R.; England, John H.

2013-07-01

The study revises the maximum extent of the northwest Laurentide Ice Sheet (LIS) in the western Canadian Arctic Archipelago (CAA) during the last glaciation and documents subsequent ice sheet retreat and glacioisostatic adjustments across western Banks Island. New geomorphological mapping and maximum-limiting radiocarbon ages indicate that the northwest LIS inundated western Banks Island after ~ 31 14C ka BP and reached a terminal ice margin west of the present coastline. The onset of deglaciation and the age of the marine limit (22-40 m asl) are unresolved. Ice sheet retreat across western Banks Island was characterized by the withdrawal of a thin, cold-based ice margin that reached the central interior of the island by ~ 14 cal ka BP. The elevation of the marine limit is greater than previously recognized and consistent with greater glacioisostatic crustal unloading by a more expansive LIS. These results complement emerging bathymetric observations from the Arctic Ocean, which indicate glacial erosion during the Last Glacial Maximum (LGM) to depths of up to 450 m.

Characterizing Arctic sea ice topography and atmospheric form drag using high-resolution IceBridge data

NASA Astrophysics Data System (ADS)

Petty, A.; Tsamados, M.; Kurtz, N. T.; Farrell, S. L.; Newman, T.; Harbeck, J.; Feltham, D. L.; Richter-Menge, J.

2015-12-01

Here we present a detailed analysis of Arctic sea ice topography using high resolution, three-dimensional surface elevation data from the NASA Operation IceBridge Airborne Topographic Mapper (ATM) laser altimeter. We derive novel ice topography statistics from 2009-2014 across both first-year and multiyear ice regimes - including the height, area coverage, orientation and spacing of distinct surface features. The sea ice topography exhibits strong spatial variability, including increased surface feature (e.g. pressure ridge) height and area coverage within the multi-year ice regions. The ice topography also shows a strong coastal dependency, with the feature height and area coverage increasing as a function of proximity to the nearest coastline, especially north of Greenland and the Canadian Archipelago. The ice topography data have also been used to explicitly calculate atmospheric drag coefficients over Arctic sea ice; utilizing existing relationships regarding ridge geometry and their impact on form drag. The results are being used to calibrate the recent drag parameterization scheme included in the sea ice model CICE.

The Impact of Stratospheric Circulation Extremes on Minimum Arctic Sea Ice Extent

NASA Astrophysics Data System (ADS)

Smith, K. L.; Polvani, L. M.; Tremblay, B.

2017-12-01

The interannual variability of summertime Arctic sea ice extent (SIE) is anti-correlated with the leading mode of extratropical atmospheric variability in preceding winter, the Arctic Oscillation (AO). Given this relationship and the need for better seasonal predictions of Arctic SIE, we here examine the role of stratospheric circulation extremes and stratosphere-troposphere coupling in linking the AO and Arctic SIE variability. We show that extremes in the stratospheric circulation during the winter season, namely stratospheric sudden warming (SSW) and strong polar vortex (SPV) events, are associated with significant anomalies in sea ice concentration in the Bering Straight and the Sea of Okhotsk in winter, the Barents Sea in spring and along the Eurasian coastline in summer in both observations and a fully-coupled, stratosphere-resolving general circulation model. The accompanying figure shows the composite mean sea ice concentration anomalies from the Whole Atmosphere Community Climate Model (WACCM) for SSWs (N = 126, top row) and SPVs (N = 99, bottom row) for winter (a,d), spring (b,e) and summer (c,f). Consistent with previous work on the AO, we find that SSWs, which are followed by the negative phase of the AO at the surface, result in sea ice growth, whereas SPVs, which are followed by the positive phase of the AO at the surface, result in sea ice loss, although the dynamic and thermodynamic processes driving these sea ice anomalies in the three Arctic regions, noted above, are different. Our analysis suggests that the presence or absence of stratospheric circulation extremes in winter may play a non-trivial role in determining total September Arctic SIE when combined with other factors.

Sea level budget in the Arctic during the satellite altimetry era

NASA Astrophysics Data System (ADS)

Carret, Alice; Cazenave, Anny; Meyssignac, Benoît; Prandi, Pierre; Ablain, Michael; Andersen, Ole; Blazquez, Alejandro

2016-04-01

Studying sea level variations in the Arctic region is challenging because of data scarcity. Here we present results of the sea level budget in the Arctic (up to 82°N) during the altimetry era. We first investigate closure of the sea level budget since 2002 using altimetry data from Envisat and Cryosat for estimating sea level, temperature and salinity data from the ORAP5 reanalysis and GRACE space gravimetry to estimate the steric and mass components. Two altimetry sea level data sets are considered (from DTU and CLS), based on Envisat waveforms retracking. Regional sea level trends seen in the altimetric map, in particular over the Beaufort Gyre and along the eastern coast of Greenland are of steric origin. However, in terms of regional average, the steric component contributes very little to the observed sea level trend, suggesting a dominant mass contribution in the Arctic region. This is confirmed by GRACE-based ocean mass time series that agree very well with the altimetry-based sea level time series. Direct estimate of the mass component is not possible prior to GRACE. Thus we estimated the mass contribution over the whole altimetry era from the difference between altimetry-based sea level and the ORAP5 steric component. Finally we compared altimetry-based coastal sea level with tide gauge records available along Norwegian, Greenland and Siberian coastlines and investigated whether the Arctic Oscillation that was the main driver of coastal sea level in the Arctic during the past decades still plays a dominant role or if other factors (e.g., of anthropogenic origin) become detectable.

Hurricane effects on the coastline from Cabo San Lucas Bay, Baja California Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Nava-Sanchez, Enrique; Navarro-Lozano, Octavio; Murillo-Jimenez, Janette; Godinez-Orta, Lucio

2010-05-01

Cabo San Lucas, located on the southern tip of the Baja California Peninsula, is on the track of two to five hurricanes per year. Thus the purpose of this work was to evaluate the effects of hurricanes on the stability of the coastline of San Lucas Bay. We apply GIS for determining inland geomorphology and conducted bathymetric surveys for the marine area. Results from previous sedimentological researches of fluvial, littoral and shallow marine environments were reanalyzed to determine the sedimentary processes responsible for the stability of the coastline. Also, we were monitoring beach profiles in the bay and also other beaches from the tip of the peninsula from 1997 to 2004 and recorded the effects of Hurricane Juliette in 2001 (category 3 in the Saffir-Simpson scale), which left an accumulative precipitation of 850 mm and formed waves of 8 m in height during the four days of maximum impact. We found out that inland and marine geomorphology, as well as littoral and alluvial sediment transport play a major role to keep the coastline relatively stable for at least the last 3,000 years. Geomorphology of the drainage basin is steep favoring the formation of flash floods that feed an alluvial fan to finally discharge sediments to the San Lucas Bay where a temporal fan-delta is developed during catastrophic rains. Marine morphology is dominated by the San Lucas submarine canyon, located on the southern half of the bay, whose canyon head is just at the foot of the beach (4 to 6 m in depth). On the northern half, there is a narrow submarine terrace with a break 40 m deep, covered mostly by fluvial sediments. At the littoral, there is only one dune ridge which is almost continuous and only cut by the arroyo. The dune ridge was dated at two levels; at the bottom, just above Pleistocene fluvial sediments and at the top, giving dates of 3200 and 800 years respectively. These dates are interpreted as an evidence for the stability of the dune ridge. The sand from the beach, responsible for the coastline stability, is sourced by two processes: (1) the littoral drift bringing sand from the Pacific coast, which turns around San Lucas Cape and enters the bay, process that is continuous, with stronger events every 3 to 7 years (matching ENSO cycles) following seasonal periods of heavy cyclonic rains that favor important fluvial sediment discharges; and (2) direct input of fluvial sediments, discharged by the El Salto arroyo during catastrophic hurricane rains with returning periods of 50 years. The canyon head traps most of the sediment "excess" of the beach system. Winter waves erode the beach and generate a weak littoral transport to the south where sediments are trapped by the canyon head. Also, because the mouth of the El Salto arroyo is just in front of the canyon head, the debris flows during catastrophic rains are dumped on the canyon and a small portion remains to form a fan delta whose sediments are later removed by waves to feed the eroded beach in both direccions, as we observed during the path of Hurricane Juliette.

Climate Adaptation and Policy-Induced Inflation of Coastal Property Value

PubMed Central

McNamara, Dylan E.; Gopalakrishnan, Sathya; Smith, Martin D.; Murray, A. Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities. PMID:25806944

Climate adaptation and policy-induced inflation of coastal property value.

PubMed

McNamara, Dylan E; Gopalakrishnan, Sathya; Smith, Martin D; Murray, A Brad

2015-01-01

Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for beach nourishment. As climatic drivers and federal policies for beach nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including beach nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.

Arctic Ice Management: an integrated approach to climate engineering

NASA Astrophysics Data System (ADS)

Desch, S. J.; Hartnett, H. E.; Groppi, C. E.; Romaniello, S. J.

2017-12-01

The warming climate is having the most rapid and pronounced effects in the high Arctic. The loss of Arctic sea ice is not only changing the physical oceanography of the Arctic Ocean and its coastlines; it is also promoting new conversations about the dangers and benefits for trade, transportation, and industry in the Arctic. The rate of decrease of summer sea ice in the Arctic is currently -300 km3 yr-1, a rate that will lead to complete loss of end-summer sea ice as soon as 2030. Preventing the strong positive feedbacks and increased warming due to sea ice albedo loss must be an important component of climate mitigation strategies. Here, we explore a direct engineering approach we call Arctic Ice Management (AIM) to reduce the loss of Arctic sea ice. We predict that pumping seawater onto the ice surface during the Arctic winter using wind-powered pumps can thicken sea ice by up to 1 m per year, reversing the current loss rates and prolonging the time until the Arctic Ocean is ice-free. Thickening sea ice would not change CO2 levels, which are the underlying cause of ice loss, but it would prevent some of the strongest feedbacks and would buy time to develop the tools and governance systems necessary to achieve carbon-neutrality. We advocate exploration of AIM as a mitigation strategy employed in parallel with CO2 reduction efforts. The opportunity and risk profiles of AIM differ from other geoengineering proposals. While similar in principle to solar radiation management, AIM may present fewer large-scale environmental risks. AIM is separate from greenhouse gas emission reduction or sequestration, but might help prevent accelerated release of methane from thawing permafrost. Further, AIM might be usefully employed at regional and local scales to preserve Arctic ecosystems and possibly reduce the effects of ice-loss induced coastal erosion. Through presentation of the AIM concept, we hope to spark new conversations between scientists, stakeholders, and decision-makers, and to provide an opportunity to expand the toolkit of geoengineering approaches for dealing with climate change.

Spatial Analysis of Coastal Erosion over Five Decades near Barrow, Alaska

NASA Astrophysics Data System (ADS)

Manley, W. F.

2004-12-01

There has been increasing interest in processes affecting Arctic coastlines, including shoreline erosion. The prospect of continued -- and possibly accelerated -- coastal erosion is a major concern for many Arctic communities. Documenting and understanding spatial variability in erosion rates are increasingly attainable as high-resolution imagery becomes available, and as GIS and remote-sensing tools are more widely accepted. This study presents such an analysis for a broad area near Barrow, Alaska. Shoreline erosion and accretion were quantified by comparison of coregistered datasets and imagery. Orthorectified Radar Imagery (ORRI) was acquired in July, 2002 at 1.25 m resolution. Twenty frames of aerial photos from August, 1955 were scanned and georectified to the ORRI using a polynomial transformation in ArcGIS, with resulting resolution of about 1.4 m and RMS error of 2.6 m. The 2002 and 1955 shorelines were digitized with points spaced every 20 m along the 250 km of mainland coastline. For barrier islands and the Barrow Spit, the 1955 coastline was digitized from DRG files depicting the USGS 15-minute maps. Using a variety of vector ArcInfo commands, horizontal displacement of the mainland shoreline was converted to erosion and accretion rates for the intervening 47 years. (Note that time-averaged rates will underrepresent episodically high rates during storm events). Overall error considering georectification, digitizing, and transient waterline shifts due to microtidal fluctuation and wave-set up is approx. 3.1 m for the mainland coast, equating with 0.07 m/yr. For barrier features, where the DRG's are less accurate, error is about 28 m (0.6 m/yr). Nearly all of the mainland coast (91%) has experienced erosion. Highly variable, rates average -0.91 m/yr, with an average horizontal shoreline displacement of -42.5 m. (Rates and displacements are negative for erosion). Relatively low rates of about -0.3 m/yr occur along the Chukchi coast, where sand- and gravel-dominated beaches are backed by bluffs up to 15 m high. Rates are higher along the low coastal plain facing Elson Lagoon, exceeding -5 m/yr near Scott, Ross, and Christie Points, before decreasing again in the sheltered waters of inner Admiralty Bay. Rates also decrease within small bays and inlets. Lateral accretion from 1955 to 2002 is uncommon, limited to short stretches of widening beach along the Chukchi coast, and isolated progradation or shifting of small nearshore spits and bars. Immediately adjacent to Barrow, the shoreline has eroded -0.2 to -0.8 m/yr, in agreement with a higher-resolution, related study, whereas the beach near the NARL/UIC complex has prograded on average +0.3 m/yr. The narrow offshore barrier islands have migrated considerably, with an average horizontal shift of 205 m. Although erosion over five decades has been locally variable, a few patterns emerge. High bluffs and coarse beach sediment help protect the Chukchi shoreline, whereas low coastal bluffs exposing ice-rich, peaty soils are susceptible along the Beaufort coast. Beyond bluff height and shoreface lithologies, fetch plays an important role, with the inner portions of bays and inlets protected at a variety of scales. Erosion appears to be more pronounced where ice-wedge polygons are strongly developed within mature thaw-lake basins. Near Barrow, human activities in the nearshore zone have played a role, and erosion is a concern -- even though it occurs there more slowly than the region as a whole. The importance of extreme weather events, and the possibility of accelerated change due to warming and decreasing summer sea ice, will be examined as other imagery improves the temporal resolution for analysis.

Atmospheric Form Drag Coefficients Over Arctic Sea Ice Using Remotely Sensed Ice Topography Data, Spring 2009-2015

NASA Technical Reports Server (NTRS)

Petty, Alek A.; Tsamados, Michel C.; Kurtz, Nathan T.

2017-01-01

Sea ice topography significantly impacts turbulent energy/momentum exchange, e.g., atmospheric (wind) drag, over Arctic sea ice. Unfortunately, observational estimates of this contribution to atmospheric drag variability are spatially and temporally limited. Here we present new estimates of the neutral atmospheric form drag coefficient over Arctic sea ice in early spring, using high-resolution Airborne Topographic Mapper elevation data from NASA's Operation IceBridge mission. We utilize a new three-dimensional ice topography data set and combine this with an existing parameterization scheme linking surface feature height and spacing to form drag. To be consistent with previous studies investigating form drag, we compare these results with those produced using a new linear profiling topography data set. The form drag coefficient from surface feature variability shows lower values [less than 0.5-1 × 10(exp. -3)] in the Beaufort/Chukchi Seas, compared with higher values [greater than 0.5-1 ×10(exp. -3)] in the more deformed ice regimes of the Central Arctic (north of Greenland and the Canadian Archipelago), which increase with coastline proximity. The results show moderate interannual variability, including a strong increase in the form drag coefficient from 2013 to 2014/2015 north of the Canadian Archipelago. The form drag coefficient estimates are extrapolated across the Arctic with Advanced Scatterometer satellite radar backscatter data, further highlighting the regional/interannual drag coefficient variability. Finally, we combine the results with existing parameterizations of form drag from floe edges (a function of ice concentration) and skin drag to produce, to our knowledge, the first pan-Arctic estimates of the total neutral atmospheric drag coefficient (in early spring) from 2009 to 2015.

Forecasting hurricane impact on coastal topography: Hurricane Ike

USGS Publications Warehouse

Plant, Nathaniel G.; Stockdon, Hilary F.; Sallenger,, Asbury H.; Turco, Michael J.; East, Jeffery W.; Taylor, Arthur A.; Shaffer, Wilson A.

2010-01-01

Extreme storms can have a profound impact on coastal topography and thus on ecosystems and human-built structures within coastal regions. For instance, landfalls of several recent major hurricanes have caused significant changes to the U.S. coastline, particularly along the Gulf of Mexico. Some of these hurricanes (e.g., Ivan in 2004, Katrina and Rita in 2005, and Gustav and Ike in 2008) led to shoreline position changes of about 100 meters. Sand dunes, which protect the coast from waves and surge, eroded, losing several meters of elevation in the course of a single storm. Observations during these events raise the question of how storm-related changes affect the future vulnerability of a coast.

Simulation of Extreme Arctic Cyclones in IPCC AR5 Experiments

NASA Astrophysics Data System (ADS)

Vavrus, S. J.

2012-12-01

Although impending Arctic climate change is widely recognized, a wild card in its expression is how extreme weather events in this region will respond to greenhouse warming. Intense polar cyclones represent one type of high-latitude phenomena falling into this category, including very deep synoptic-scale cyclones and mesoscale polar lows. These systems inflict damage through high winds, heavy precipitation, and wave action along coastlines, and their impact is expected to expand in the future, when reduced sea ice cover allows enhanced wave energy. The loss of a buffering ice pack could greatly increase the rate of coastal erosion, which has already been increasing in the Arctic. These and related threats may amplify if extreme Arctic cyclones become more frequent and/or intense in a warming climate with much more open water to fuel them. This possibility has merit on the basis of GCM experiments, which project that greenhouse forcing causes lower mean sea level pressure (SLP) in the Arctic and a strengthening of the deepest storms over boreal high latitudes. In this study, the latest Coupled Model Intercomparison Project (CMIP5) climate model output is used to investigate the following questions: (1) What are the spatial and seasonal characteristics of extreme Arctic cyclones? (2) How well do GCMs simulate these phenomena? (3) Are Arctic cyclones already showing the expected response to greenhouse warming in climate models? To address these questions, a retrospective analysis is conducted of the transient 20th century simulations among the CMIP5 GCMs (spanning years 1850-2005). The results demonstrate that GCMs are able to reasonably represent extreme Arctic cyclones and that the simulated characteristics do not depend significantly on model resolution. Consistent with observational evidence, climate models generate these storms primarily during winter and within the climatological Aleutian and Icelandic Low regions. Occasionally the cyclones remain very intense over the Arctic Ocean. The historical tendency in Arctic SLP varies considerably among the GCMs, but the intermodel average trend exhibits a lowering of mean-annual pressure over the Arctic during the past 150 years and an increase in extreme cyclones in the vicinity of the Aleutian and Icelandic Lows. However, only weak trends in extreme cyclones are simulated through 2005 over the Arctic Ocean, where simulations of future climate change produce the largest SLP falls.

Ice Shelf Microbial Ecosystems in the High Arctic and Implications for Life on Snowball Earth

NASA Astrophysics Data System (ADS)

Vincent, W. F.; Gibson, J. A. E.; Pienitz, R.; Villeneuve, V.; Broady, P. A.; Hamilton, P. B.; Howard-Williams, C.

The Ward Hunt Ice Shelf (83°N, 74°W) is the largest remaining section of thick (>10m) landfast sea ice along the northern coastline of Ellesmere Island, Canada. Extensive meltwater lakes and streams occur on the surface of the ice and are colonized by photosynthetic microbial mat communities. This High Arctic cryo-ecosystem is similar in several of its physical, biological and geochemical features to the McMurdo Ice Shelf in Antarctica. The ice-mats in both polar regions are dominated by filamentous cyanobacteria but also contain diatoms, chlorophytes, flagellates, ciliates, nematodes, tardigrades and rotifers. The luxuriant Ward Hunt consortia also contain high concentrations (107-108cm-2) of viruses and heterotrophic bacteria. During periods of extensive ice cover, such as glaciations during the Proterozoic, cryotolerant mats of the type now found in these polar ice shelf ecosystems would have provided refugia for the survival, growth and evolution of a variety of organisms, including multicellular eukaryotes.

Beluga whale liver microsomal cytochrome P4501A (CYP1A) enzymes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bullock, P.L.; Addison, R.; Lockhart, L.

1995-12-31

Beluga whale (Delphinapterus leucas) liver from the Canadian arctic was analyzed for the presence of CYP1A enzymes, as part of current studies on biomarkers for environmental contamination. CYP1A1-associated 7-ethoxyresorufin O-dealkylase activity (EROD) varied 13 fold among sixteen male whale liver microsomal samples and 31 fold among five females. Similarly, the rate of 7-methoxyresorufin O-dealkylation (MROD) varied 7 fold and 3 fold in microsomal samples from males and females, respectively. Furthermore, 7-pentoxyresorufin O-dealkylase activity (PROD) varied 10 fold in both sexes. None of these enzyme activities were sexually differentiated, and EROD and MROD were inhibited by {alpha}-naphthoflavone. There was very goodmore » correlation between EROD and MROD (r{sup 2} = .894), EROD and PROD (r{sup 2} = .909), but MROD and PROD were not as well correlated (r{sup 2} = 785). On Western immunoblots, a single band was recognized in Beluga whale liver microsomes by a polygonal antibody raised against an oligopeptide related to trout CYP1A1. This antibody also recognized purified rat CYP1A1 (56 kDa) and stained only one band (56 kDa) in liver microsomes isolated from male rats treated with {beta}-naphthoflavone. The interindividual variation in EROD paralleled differences in the amount of whale liver microsomal protein that cross-reacted with the anti-peptide antibody. The results suggest that Beluga whale liver contains at least one CYP1A enzyme which catalyzes the 0-dealkylation of 7-ethoxy, 7-methoxy and 7-pentoxyresorufin and has a molecular weight less than that of rat CYP1A1, but similar to rat CYP1A2 (52 kDa).« less

Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and harlequin ducks (Histronicus histronicus) in the Eastern Aleutian Islands, Alaska, USA

USGS Publications Warehouse

Miles, A.K.; Flint, Paul L.; Trust, K.A.; Ricca, M.A.; Spring, S.E.; Arrieta, D.E.; Hollmen, T.; Wilson, B.W.

2007-01-01

Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([Mytilus trossilus] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (∼1,180–5,980 ng/g) approached those found at highly contaminated sites (∼4,100–7,500 ng/g).

The Oliktok Point Arctic Research Facility (OPARF)

NASA Astrophysics Data System (ADS)

Zak, B. D.; Ivey, M.

2011-12-01

For the past year, the US Department of Energy, through Sandia National Laboratories, has operated a Designated User Facility at Oliktok Point Alaska, on the Arctic Ocean coast near the western end of the Prudhoe Bay oil fields. The primary purpose of this user facility is to accommodate and support manned and unmanned airborne measurement platforms over the Arctic Ocean and adjacent coastline as the arctic sea ice recedes. The speed at which the sea ice is receding exceeds model-projected speeds considerably for reasons that are not fully understood. The ultimate objective is to incorporate improved understanding of the radiative and other processes impacting sea ice recession into the relevant climate models. OPARF is based at a USAF Long Range Radar Station, an old Distant Early Warning (DEW) radar station built during the height of the Cold War, but continuing to be operated to track air traffic over the pole. The USAF has graciously granted Sandia and DOE use of selected facilities at Oliktok on a non-interference basis. DOE also maintains FAA-granted Restricted Airspace over Oliktok Point and adjacent ocean. In addition, DOE has also requested that the FAA establish a Warning Area over international waters 30 miles wide and 700 miles long stretching from near Oliktok towards the North Pole. That request is currently being processed by the FAA, with the public comment period now closed. This paper will update OPARF developments for potential users of the Oliktok user facility and other interested researchers.

Thermal erosion of a permafrost coastline: Improving process-based models using time-lapse photography

USGS Publications Warehouse

Wobus, C.; Anderson, R.; Overeem, I.; Matell, N.; Clow, G.; Urban, F.

2011-01-01

Coastal erosion rates locally exceeding 30 m y-1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where coastal erosion rates have averaged 10-15 m y-1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.

Electronic atlas of the Russian Arctic coastal zone: natural conditions and technogenic risk

NASA Astrophysics Data System (ADS)

Drozdov, D. S.; Rivkin, F. M.; Rachold, V.

2004-12-01

The Arctic coast is characterized by a diversity of geological-geomorphological structures and geocryological conditions, which are expected to respond differently to changes in the natural environment and in anthropogenic impacts. At present, oil fields are prospected and developed and permanent and temporary ports are constructed in the Arctic regions of Russia. Thus, profound understanding of the processes involved and measures of nature conservation for the coastal zone of the Arctic Seas are required. One of the main field of Arctic coastal investigations and database formation of coastal conditions is the mapping of the coasts. This poster presents a set of digital maps including geology, quaternary sediments, landscapes, engineering-geology, vegetation, geocryology and a series of regional sources, which have been selected to characterize the Russian Arctic coast. The area covered in this work includes the 200-km-wide band along the entire Russian Arctic coast from the Norwegian boundary in the west to the Bering Strait in the east. Methods included the collection of the majority of available hard copies of cartographic material and their digital formats and the transformation of these sources into a uniform digital graphic format. The atlas consists of environmental maps and maps of engineering-geological zoning. The set of environmental maps includes geology, quaternary sediments, landscapes and vegetation of the Russian Arctic coast at a scale of 1:4000000. The set of engineering-geocryological maps includes a map of engineering-geocryological zoning of the Russian Arctic coast, a map of the intensity of destructive coastal process and a map of industrial impact risk assessment ( 1:8000000 scale). Detailed mapping has been performed for key sites (at a scale of 1:100000) in order to enable more precise estimates of the intensity of destructive coastal process and industrial impact. The engineering-geocryological map of the Russian Arctic coast was compiled based on the analysis of geotechnical and geocryological conditions in the areas adjacent to the coastal band. Industrial impact assessment has been estimated differently for each engineering-geocryological region distinguished on the coast, considering technological features of construction and engineering facilities: aerial construction, highways and airdromes, underground (with positive and negative pipe temperatures) and surface pipelines and quarries. The atlas is being used as a base for the circum-Arctic segmentation of the coastline and the analyses of coastal dynamics within the Arctic Coastal Dynamics (ACD) Project. The work has been supported by INTAS (project number 01-2332).

Mesoscale high-resolution modeling of extreme wind speeds over western water areas of the Russian Arctic

NASA Astrophysics Data System (ADS)

Platonov, Vladimir S.; Kislov, Alexander V.

2016-11-01

A statistical analysis of extreme weather events over coastal areas of the Russian Arctic based on observational data has revealed many interesting features of wind velocity distributions. It has been shown that the extremes contain data belonging to two different statistical populations. Each of them is reliably described by a Weibull distribution. According to the standard terminology, these sets of extremes are named ‘black swans’ and ‘dragons’. The ‘dragons’ are responsible for most extremes, surpassing the ‘black swans’ by 10 - 30 %. Since the data of the global climate model INM-CM4 do not contain ‘dragons’, the wind speed extremes are investigated on the mesoscale using the COSMO-CLM model. The modelling results reveal no differences between the ‘swans’ and ‘dragons’ situations. It could be associated with the poor sample data used. However, according to many case studies and modeling results we assume that it is caused by a rare superposition of large-scale synoptic factors and many local meso- and microscale factors (surface, coastline configuration, etc.). Further studies of extreme wind speeds in the Arctic, such as ‘black swans’ and ‘dragons’, are necessary to focus on non-hydrostatic high-resolution atmospheric modelling using downscaling techniques.

Long-term cliff retreat and erosion hotspots along the central shores of the Monterey Bay National Marine Sanctuary

USGS Publications Warehouse

Moore, Laura J.; Griggs, Gary B.

2002-01-01

Quantification of cliff retreat rates for the southern half of Santa Cruz County, CA, USA, located within the Monterey Bay National Marine Sanctuary, using the softcopy/geographic information system (GIS) methodology results in average cliff retreat rates of 7–15 cm/yr between 1953 and 1994. The coastal dunes at the southern end of Santa Cruz County migrate seaward and landward through time and display net accretion between 1953 and 1994, which is partially due to development. In addition, three critically eroding segments of coastline with high average erosion rates ranging from 20 to 63 cm/yr are identified as erosion ‘hotspots’. These locations include: Opal Cliffs, Depot Hill and Manresa. Although cliff retreat is episodic, spatially variable at the scale of meters, and the factors affecting cliff retreat vary along the Santa Cruz County coastline, there is a compensation between factors affecting retreat such that over the long-term the coastline maintains a relatively smooth configuration. The softcopy/GIS methodology significantly reduces errors inherent in the calculation of retreat rates in high-relief areas (e.g. erosion rates generated in this study are generally correct to within 10 cm) by removing errors due to relief displacement. Although the resulting root mean squared error for erosion rates is relatively small, simple projections of past erosion rates are inadequate to provide predictions of future cliff position. Improved predictions can be made for individual coastal segments by using a mean erosion rate and the standard deviation as guides to future cliff behavior in combination with an understanding of processes acting along the coastal segments in question. This methodology can be applied on any high-relief coast where retreat rates can be measured.

National assessment of hurricane-induced coastal erosion hazards--Gulf of Mexico

USGS Publications Warehouse

Stockdon, Hilary F.; Doran, Kara S.; Thompson, David M.; Sopkin, Kristin L.; Plant, Nathaniel G.; Sallenger, Asbury H.

2012-01-01

Sandy beaches provide a natural barrier between the ocean and inland communities, ecosystems, and resources. However, these dynamic environments move and change in response to winds, waves, and currents. During a hurricane, these changes can be large and sometimes catastrophic. High waves and storm surge act together to erode beaches and inundate low-lying lands, putting inland communities at risk. A decade of USGS research on storm-driven coastal change hazards has provided the data and modeling capabilities to identify areas of our coastline that are likely to experience extreme and potentially hazardous erosion during a hurricane. This report defines hurricane-induced coastal erosion hazards for sandy beaches along the U.S. Gulf of Mexico coastline. The analysis is based on a storm-impact scaling model that uses observations of beach morphology combined with sophisticated hydrodynamic models to predict how the coast will respond to the direct landfall of category 1-5 hurricanes. Hurricane-induced water levels, due to both surge and waves, are compared to beach and dune elevations to determine the probabilities of three types of coastal change: collision (dune erosion), overwash, and inundation. As new beach morphology observations and storm predictions become available, this analysis will be updated to describe how coastal vulnerability to storms will vary in the future.

Climate impacts on northern Canada: regional background.

PubMed

Prowse, Terry D; Furgal, Chris; Bonsal, Barrie R; Peters, Daniel L

2009-07-01

Understanding the implications of climate change on northern Canada requires a background about the size and diversity of its human and biogeophysical systems. Occupying an area of almost 40% of Canada, with one-third of this contained in Arctic islands, Canada's northern territories consist of a diversity of physical environments unrivaled around the circumpolar north. Major ecozones composed of a range of landforms, climate, vegetation, and wildlife include: Arctic, boreal and taiga cordillera; boreal and taiga plains; taiga shield; and northern and southern Arctic. Although generally characterized by a cold climate, there is an enormous range in air temperature with mean annual values being as high as -5 degrees C in the south to as low as -20 degrees C in the high Arctic islands. A similar contrast characterizes precipitation, which can be > 700 mm y(-1) in some southern alpine regions to as low as 50 mm y(-1) over islands of the high Arctic. Major freshwater resources are found within most northern ecozones, varying from large glaciers or ice caps and lakes to extensive wetlands and peat lands. Most of the North's renewable water, however, is found within its major river networks and originates in more southerly headwaters. Ice covers characterize the freshwater systems for multiple months of the year while permafrost prevails in various forms, dominating the terrestrial landscape. The marine environment, which envelops the Canadian Arctic Archipelago, is dominated by seasonal to multiyear sea ice often several meters thick that plays a key role in the regional climate. Almost two-thirds of northern Canadian communities are located along coastlines with the entire population being just over 100 000. Most recent population growth has been dominated by an expansion of nonaboriginals, primarily the result of resource development and the growth of public administration. The economies of northern communities, however, remain quite mixed with traditional land-based renewable resource-subsistence activities still being a major part of many local economies.

U.S. Geological Survey Geospatial Data To Support STEM Education And Communication

NASA Astrophysics Data System (ADS)

Molnia, B. F.

2017-12-01

The U.S. Geological Survey (USGS) has a long history of contributing to STEM education, outreach, and communication. The USGS EarthExplorer website: https://earthexplorer.usgs.gov is the USGS gateway to more than 150 geospatial data sets that are freely available to STEM students, educators, and researchers. Two in particular, Global Fiducials data and Declassified Satellite Imagery provide the highest resolution visual record of the Earth's surface that is available for unlimited, unrestricted download. Global Fiducials Data - Since the mid-1990s, more than 500 locations, each termed a 'Fiducial Site', have been systematically and repeatedly imaged with U.S. National Imagery Systems space-based sensors. Each location was selected for long-term monitoring, based on its history and environmental values. Since 2008, imagery from about a quarter of the sites has been publicly released and is available on EarthExplorer. These 5,000 electro-optical (EO) images, with 1.0 - 1.3 m resolution, comprise more than 140 time-series. Individual time-series focus on wildland fire recovery, Arctic sea ice change, Antarctic habitats, temperate glacier behavior, eroding barrier islands, coastline evolution, resource and ecosystem management, natural disaster response, global change studies, and other topics. Declassified Satellite Imagery - Nearly 1 million declassified photographs, collected between 1960 and 1984, by U.S. intelligence satellites KH-1 through KH-9 have been released to the public. The USGS has copies of most of the released film and provides a digital finding aid that can be accessed from the USGS EarthExplorer website. Individual frames were collected at resolutions that range from 0.61 m - 7.6 m. Imagery exists for locations on all continents. Combined with Landsat imagery, also available from the USGS EarthExplorer website, the STEM Community has access to more than 7.5 million images providing nearly 50 years of visual observations of Earth's dynamic surface.

Polycyclic aromatic hydrocarbons in ocean sediments from the North Pacific to the Arctic Ocean.

PubMed

Ma, Yuxin; Halsall, Crispin J; Xie, Zhiyong; Koetke, Danijela; Mi, Wenying; Ebinghaus, Ralf; Gao, Guoping

2017-08-01

Eighteen polycyclic aromatic hydrocarbons (PAHs) were measured in surficial sediments along a marine transect from the North Pacific into the Arctic Ocean. The highest average Σ 18 PAHs concentrations were observed along the continental slope of the Canada Basin in the Arctic (68.3 ± 8.5 ng g -1 dw), followed by sediments in the Chukchi Sea shelf (49.7 ± 21.2 ng g -1 dw) and Bering Sea (39.5 ± 11.3 ng g -1 dw), while the Bering Strait (16.8 ± 7.1 ng g -1 dw) and Central Arctic Ocean sediments (13.1 ± 9.6 ng g -1 dw) had relatively lower average concentrations. The use of principal components analysis with multiple linear regression (PCA/MLR) indicated that on average oil related or petrogenic sources contributed ∼42% of the measured PAHs in the sediments and marked by higher concentrations of two methylnaphthalenes over the non-alkylated parent PAH, naphthalene. Wood and coal combustion contributed ∼32%, and high temperature pyrogenic sources contributing ∼26%. Petrogenic sources, such as oil seeps, allochthonous coal and coastally eroded material such as terrigenous sediments particularly affected the Chukchi Sea shelf and slope of the Canada Basin, while biomass and coal combustion sources appeared to have greater influence in the central Arctic Ocean, possibly due to the effects of episodic summertime forest fires. Copyright © 2017 Elsevier Ltd. All rights reserved.

OCoc- from Ocean Colour to Organic Carbon

NASA Astrophysics Data System (ADS)

Heim, B.; Overduin, P. P.; Schirrmeister, L.; Doerffer, R.

2009-04-01

Enhanced permafrost warming and increased arctic river discharges have heightened concern about the input of terrigenous matter into Arctic coastal waters. Especially, large parts of the Central and Eastern Siberian coastline are characterized by highly erosive sedimentary ice-rich material. The ‘OCoc-from Ocean Colour to Organic Carbon' project (IPY-project 1176), funded by the German Research Foundation (DFG), is an Ocean Colour study joined with the Arctic Circum-polar Coastal Observatory Network Acco-Net (ACCO-Net: IPY-project 90) originating from the Arctic Coastal Dynamics ACD project . OCoc uses Ocean Colour satellite data for synoptic monitoring of the input of organic matter - from both fluvial and coastal sources - into the Arctic coastal waters. Initial results from the German-Russian Expedition Lena08 along the southeastern Laptev Sea Coast (Arctic Siberia, Russia) in August 2008 are presented. Ocean Colour MERIS Reduced Resolution (RR)-LIB data of the Laptev Sea Coast from August 2008 have been processed towards L2 parameters using Beam-Visat4.2© and the MERIS case2 regional processor for coastal application (C2R). C2R uses neural network procedures for the retrieval of water leaving reflectances and neural network procedures to derive the inherent optical properties (IOPs) from the water leaving reflectances. C2R output parameters are IOPs (absorption and backscattering coefficients), apparent optical properties (AOPs) (water leaving radiance reflectance, attenuation coefficient ‘k'), optical parameters such as the first attenuation depth (‘Z90') and calculated concentrations of chlorophyll, total suspended matter, and yellow substance absorption. Initial comparisons with Lena08-Expedition data (Secchi depths, cDOM) and water transparency data from former arctic cruises show that the MERIS-C2R optical parameters 'total absorption' and the first attenuation depth, 'Z90', seem adequately to represent true conditions. High attenuation values are the tracers for the organic-rich terrigenous input. The synoptic information of MERIS Ocean Colour products will provide valuable spatial and dynamical information on the Organic Carbon and sediment fluxes from the Siberian permafrost coast.

Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic.

PubMed

Iverson, Samuel A; Gilchrist, H Grant; Smith, Paul A; Gaston, Anthony J; Forbes, Mark R

2014-03-22

Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems.

Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic

PubMed Central

Iverson, Samuel A.; Gilchrist, H. Grant; Smith, Paul A.; Gaston, Anthony J.; Forbes, Mark R.

2014-01-01

Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears’ ability to meet their energetic demands. In this study, we examined polar bears’ use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010–2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator–prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems. PMID:24500172

Quantification of physical and economic impacts of climate change on public infrastructure in Alaska and benefits of global greenhouse gas mitigation

NASA Astrophysics Data System (ADS)

Melvin, A. M.; Larsen, P.; Boehlert, B.; Martinich, J.; Neumann, J.; Chinowsky, P.; Schweikert, A.; Strzepek, K.

2015-12-01

Climate change poses many risks and challenges for the Arctic and sub-Arctic, including threats to infrastructure. The safety and stability of infrastructure in this region can be impacted by many factors including increased thawing of permafrost soils, reduced coastline protection due to declining arctic sea ice, and changes in inland flooding. The U.S. Environmental Protection Agency (EPA) is coordinating an effort to quantify physical and economic impacts of climate change on public infrastructure across the state of Alaska and estimate how global greenhouse gas (GHG) mitigation may avoid or reduce these impacts. This research builds on the Climate Change Impacts and Risk Analysis (CIRA) project developed for the contiguous U.S., which is described in an EPA report released in June 2015. We are using a multi-model analysis focused primarily on the impacts of changing permafrost, coastal erosion, and inland flooding on a range of infrastructure types, including transportation (e.g. roads, airports), buildings and harbors, energy sources and transmission, sewer and water systems, and others. This analysis considers multiple global GHG emission scenarios ranging from a business as usual future to significant global action. These scenarios drive climate projections through 2100 spanning a range of outcomes to capture variability amongst climate models. Projections are being combined with a recently developed public infrastructure database and integrated into a version of the Infrastructure Planning Support System (IPSS) we are modifying for use in the Arctic and sub-Arctic region. The IPSS tool allows for consideration of both adaptation and reactive responses to climate change. Results of this work will address a gap in our understanding of climate change impacts in Alaska, provide estimates of the physical and economic damages we may expect with and without global GHG mitigation, and produce important insights about infrastructure vulnerabilities in response to warming at northern latitudes.

Investigating Coastal Processes Responsible for Large-Scale Shoreline Responses to Human Shoreline Stabilization

NASA Astrophysics Data System (ADS)

Slott, J. M.; Murray, A. B.; Ashton, A. D.

2006-12-01

Human shoreline stabilization practices, such as beach nourishment (i.e. placing sand on an eroding beach), have become more prevalent as erosion threatens coastal communities. On sandy shorelines, recent experiments with a numerical model of shoreline change (Slott, et al., in press) indicate that moderate shifts in storminess patterns, one possible outcome of global warming, may accelerate the rate at which shorelines erode or accrete, by altering the angular distribution of approaching waves (the `wave climate'). Accelerated erosion would undoubtedly place greater demands on stabilization. Scientists and coastal engineers have typically only considered the site-specific consequences of shoreline stabilization; here we explore the coastal processes responsible for large-scale (10's kms) and long-term (decades) effects using a numerical model developed by Ashton, et al. (2001). In this numerical model, waves breaking at oblique angles drive a flux of sediment along the shoreline, where gradients in this flux can shape the coastline into surprisingly complex forms (e.g. cuspate-capes found on the Carolina coast). Wave "shadowing" plays a major role in shoreline evolution, whereby coastline features may block incoming waves from reaching distant parts. In this work, we include beach nourishment in the Ashton, et al. (2001) model. Using a cuspate-cape shoreline as our initial model condition, we conducted pairs of experiments and varied the wave-climate forcing across each pair, each representing different storminess scenarios. Here we report on one scenario featuring increased extra-tropical storm influence. For each experiment-pair we ran a control experiment with no shoreline stabilization and a second where a beach nourishment project stabilized a cape tip. By comparing the results of these two parallel runs, we isolate the tendency of the shoreline to migrate landward or seaward along the domain due solely to beach nourishment. Significant effects from beach nourishment reached several tens of kilometers away from the nourishment project. The magnitude of these effects rivaled the erosion we expect from sea-level rise alone over the coming century. Furthermore, the nature of the effects were unexpected: where we expect beach nourishment sand to spread laterally in the direction of net alongshore sediment transport (e.g. to the right looking off-shore), coastline segments to the right of the cape should tend to migrate seaward, while segments to the left of the cape might naively be expected to feel little effects. We observed, however, that shoreline segments to the left (right) of the stabilized cape tip tended to migrate seaward (landward). Two statistics we collected for each model run--the extent of wave shadowing and the net flux of sediment at each alongshore position--helped explain the surprising behavior. By pinning the location of the cape tip, beach nourishment altered the way in which the cape shadowed adjacent coastlines. The stabilized cape-tip shadowed segments to the left more often, increasing the influence from left-approaching waves. These shoreline segments shifted seaward, relative to the non-nourishment case, through a convergence in alongshore sediment transport from increased transport from the left, rather than from laterally-spreading beach nourishment sand. The stabilized cape-tip shadowed segments to the right less often, increasing the influence of left-approaching waves. These segments shifted landward through a divergence in alongshore sediment transport from increased transport to the right.

Relative sea level and coastal environments in arctic Alaska during Marine Isotope Stage 5

NASA Astrophysics Data System (ADS)

Farquharson, L. M.; Mann, D. H.; Jones, B. M.; Rittenour, T. M.; Grosse, G.; Groves, P.

2015-12-01

Marine Isotope Stage (MIS) 5 was characterized by marked fluctuations in climate, the warmest being MIS 5e (124-119 ka) when relative sea level (RSL) stood 2-10 m higher than today along many coastlines. In northern Alaska, marine deposits now 5-10 m above modern sea level are assigned to this time period and termed the Pelukian transgression (PT). Complicating this interpretation is the possibility that an intra-Stage 5 ice shelf extended along the Alaskan coast, causing isostatic depression along its grounded margins, which caused RSL highs even during periods of low, global RSL. Here we use optically stimulated luminescence (OSL) to date inferred PT deposits on the Beaufort Sea coastal plain. A transition from what we interpret to be lagoonal mud to sandy tidal flat deposits lying ~ 2.75 m asl dates to 113+/-18 ka. Above this, a 5-m thick gravelly barrier beach dates to 95 +/- 20 ka. This beach contains well-preserved marine molluscs, whale vertebrae, and walrus tusks. Pleistocene-aged ice-rich eolian silt (yedoma) blanket the marine deposits and date to 57.6 +/-10.9 ka. Our interpretation of this chronostratigraphy is that RSL was several meters higher than today during MIS 5e, and lagoons or brackish lakes were prevalent. Gravel barrier beaches moved onshore as local RSL rose further after MIS 5e. The error range of the OSL age of the barrier-beach unit spans the remaining four substages of MIS 5; however, the highstand of RSL on this arctic coastline appears to occurr after the warmest part of the last interglacial and appears not to be coeval with the eustatic maximum reached at lower latitudes during MIS 5. One possibility is that RSL along the Beaufort Sea coast was affected by isostatic depression caused by an ice shelf associated with widespread, intra-Stage 5 glaciation that was out of phase with lower latitude glaciation and whose extent and timing remains enigmatic.

Engaging Local Communities in Arctic Observing Networks: A Collaborative Shoreline Change Risk WebGIS for Alaska's Arctic Slope Region

NASA Astrophysics Data System (ADS)

Brady, M.

2017-12-01

This study engaged local community stakeholders in Alaska's Arctic Slope Region to develop a web-based shoreline change risk geographic information system (WebGIS) in collaboration with the North Slope Borough and its residents. The value of the effort includes rich spatial documentation of local risks across the vast, remote, and rapidly changing shoreline, and identification of local manager information needs to direct WebGIS development. The study advances our understanding of shoreline change problems from the perspective of local Arctic communities beyond municipal impacts while building decision support. Over fifty local residents in three communities with collective coastal knowledge that extends across the National Petroleum Reserve - Alaska and Arctic National Wildlife Refuge shared their perspectives on hard copy maps. Sixteen managers provided usability perceptions of a beta WebGIS with shoreline change susceptibility information summarized at relevant asset locations such as subsistence camps. The hard copy maps with 300 "problem places" were digitized for analysis, which revealed problems across the coastline, especially challenges to boating for subsistence hunting such as shoaling cutting off access and creating hazards. The usability workshop revealed specific information needs including the need to monitor impacts at decommissioned national defense radar sites repurposed by locals to centralize oil and gas activity. These results were analyzed using an Instructional Systems Design (ISD) framework consisting of front-end and formative WebGIS evaluation phases. The front-end evaluation is the local input on hard copy maps, which provided local verification of coastal risks. The formative evaluation is the usability workshop with managers, which informed WebGIS development while promoting user buy-in. In terms of product and process, the local knowledge and information needs collected are significant because they establish local engagement with the WebGIS. The engagement is significant because the WebGIS can link local communities with Arctic Observing Networks (AON) that monitor the environmental factors used in the system. This engagement is important for advancing the dual role of AONs for providing both environmental understanding and stakeholder decision support.

Sediment contribution from coastal-cliff erosion into the Nile's littoral cell and its significance to cliff-retreat mitigation efforts

NASA Astrophysics Data System (ADS)

Katz, Oded; Mushkin, Amit; Crouvi, Onn; Alter, Samuel; Shemesh, Ran

2017-04-01

In 2013 the government of Israel initiated a national mitigation program aimed to prevent further collapse and retreat of the country's coastal cliffs, which occur along the northern termination of the Niles's littoral cell (NLC) in the eastern Mediterranean. The goals of this large-scale program are to protect infrastructure and property proximal to the cliff and to conduct long-term maintenance and monitoring of this highly dynamic and sensitive land-sea interface that spans 40 km of Israel's coast line. Here, we examine the possible impact of proposed cliff retreat mitigation efforts on long-shore sediment transport (LST) and coastal dynamics in the region. We used airborne LiDAR spanning a 9-year period between 2006 and 2015 to quantify the annual contribution of sediment eroded from a 20-km-long segment of Israel's coastal cliffs into the NLC. Our measurements reveal 282±85*103 m3 of sediment eroded from the cliff and delivered into the NLC during the studied period. Considering our study area comprises 50% of Israel's sea cliffs we infer an average contribution rate of 30,000-60,000 m^3/yr of cliff-derived sediment into the NLC prior to the planned broad-scale implementation of cliff-retreat mitigation measures. Previous studies report an average net LST flux of 80,000 - 90,000 m3 that reaches the northern termination of the NLC at Haifa Bay annually. Thus, our results suggest that Israel's actively eroding coastal cliffs are primary contributors (40-80%) to the LST budget along the northern termination of the NLC. It therefore appears that successful implementation of the coastal-cliff protection program along Israel's coastline will result in a significant sand deficit, which may drive LST in this part of the NLC out of its 'background' state. In the likely case that the energy/currents driving LST do not change, a possible outcome of this sediment deficit could be increased beach erosion along Israel's coast line to make up for the lost volumes of cliff-eroded sediments.

Sediment contribution from coastal-cliff erosion into the Nile's littoral cell and its significance to cliff-retreat mitigation efforts

NASA Astrophysics Data System (ADS)

Katz, O.; Mushkin, A.; Crouvi, O.; Alter, S.; Shemesh, R.

2016-12-01

In 2013 the government of Israel initiated a national mitigation program aimed to prevent further collapse and retreat of the country's coastal cliffs, which occur along the northern termination of the Niles's littoral cell (NLC) in the eastern Mediterranean. The goals of this large-scale program are to protect infrastructure and property proximal to the cliff and to conduct long-term maintenance and monitoring of this highly dynamic and sensitive land-sea interface that spans 40 km of Israel's coast line. Here, we examine the possible impact of proposed cliff retreat mitigation efforts on long-shore sediment transport (LST) and coastal dynamics in the region. We used airborne LiDAR spanning a 9-year period between 2006 and 2015 to quantify the annual contribution of sediment eroded from a 20-km-long segment of Israel's coastal cliffs into the NLC. Our measurements reveal 282±85*103 m3 of sediment eroded from the cliff and delivered into the NLC during the studied period. Considering our study area comprises 50% of Israel's sea cliffs we infer an average contribution rate of 30,000-60,000 m3/yr of cliff-derived sediment into the NLC prior to the planned broad-scale implementation of cliff-retreat mitigation measures. Previous studies report an average net LST flux of 80,000 - 90,000 m3 that reaches the northern termination of the NLC at Haifa Bay annually. Thus, our results suggest that Israel's actively eroding coastal cliffs are primary contributors (40-80%) to the LST budget along the northern termination of the NLC. It therefore appears that successful implementation of the coastal-cliff protection program along Israel's coastline will result in a significant sand deficit, which may drive LST in this part of the NLC out of its `background' state. In the likely case that the energy/currents driving LST do not change, a possible outcome of this sediment deficit could be increased beach erosion along Israel's coast line to make up for the lost volumes of cliff-eroded sediments.

Erosion of organic carbon in the Arctic as a geological carbon dioxide sink.

PubMed

Hilton, Robert G; Galy, Valier; Gaillardet, Jérôme; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Gröcke, Darren R; Coxall, Helen; Bouchez, Julien; Calmels, Damien

2015-08-06

Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release. However, some of this soil organic carbon may be eroded and transferred to rivers. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean, and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 ± 800 years, much older than the POC in large tropical rivers. From the measured biospheric POC content and variability in annual sediment yield, we calculate a biospheric POC flux of 2.2(+1.3)(-0.9) teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin. Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink.

Observations and Impacts of Permafrost Thaw in the Lower Yukon River Basin and Yukon Delta Region: the Importance of Local Knowledge

NASA Astrophysics Data System (ADS)

Herman-Mercer, N. M.; Elder, K.; Toohey, R.; Mutter, E. A.

2015-12-01

In regions of the arctic and subarctic baseline measurements of permafrost dynamics are lacking and scientific research can be especially expensive when remote sensing techniques are utilized. This research demonstrated the importance of local observations, a powerful tool for understanding landscape change, such as permafrost dynamics. Fifty-five interviews were recently conducted with community members in four villages of the lower Yukon River Basin and Yukon Delta to understand local environmental and landscape changes and the impacts these changes may be having on the lives and livelihoods of these communities. The interviews were semi-structured and focused on many climate and landscape change factors including knowledge of permafrost in their community or the surrounding landscape. All positive respondents stated that they believe the permafrost is thawing. The research revealed that residents of the arctic and subarctic interact with permafrost in a variety of ways. Some people utilize permafrost to store food resources and have found that they have to dig deeper presently than in their youth in order to find ground cold enough. Others are involved in digging graves and report encountering easier excavation in recent years. Subsistence hunters and gatherers travel long distances by snowmobile and boat, and have noticed slumping ground, eroding river banks and coast lines, as well as land that seems to be rising. Finally, all residents of the arctic and subarctic interact with permafrost in terms of the stability of their homes and other infrastructure. Many interview participants complained of their houses leaning and needing more frequent adjustment than in the past. Indigenous residents of the arctic and subarctic have intimate relationships with their landscape owing to their subsistence lifestyle and are also connected to the landscape of the past through the teachings of their elders. Further, arctic and subarctic communities will sustain the majority of the impacts of permafrost degradation as the infrastructure of their communities is affected. Local residents have much to add to the study of permafrost in the arctic and subarctic. Ultimately, arctic and subarctic research will benefit most from the careful integration of local observations and physical science techniques.

Arctic Ocean UNCLOS Article 76 Work for Greenland Starts on Land

NASA Astrophysics Data System (ADS)

Dahl-Jensen, T.; Marcussen, C.; Jackson, R.; Voss, P.

2005-12-01

One of the most lonely and desolate stretches of coastline on the planet has become the target for UNCLOS article 76 related research. The Danish Continental Shelf Project has launched a work program to investigate the possibilities for Greenland to claim an area outside the 200 nm limit in the Arctic Ocean. The role of the Lomonosov Ridge as a Natural Prolongation of Greenland/Canada is an important issue, and in order to better evaluate the connection between Greenland and the Lomonosov Ridge the nature of not only the ridge but also of Northern Greenland is the target of deep crustal investigations. The North Greenland Fold belt covers the ice-free part of North Greenland and continues west in the Canadian Arctic. The foldbelt was formed during the Ellesmerian orogeny, where sediments from the Franklinian Basin where compressed and deformed. The deep structure of basin and its subsequent closure are broadly unknown. Three broad band earthquake seismological stations where installed in North Greenland to supplement the existing stations at Alert (Canada) and Station Nord to the east, and the first data was available summer 2005. Crustal thickness data from these first results are presented. Plans for the spring 2006 consist of wide-angle acquisition on the sea ice from the Greenland-Canadian mainland out onto the Lomonosov Ridge, a joint Danish - Canadian project with a 400 km long profile over difficult ice conditions, 18 tons of explosives, three helicopters, a Twin Otter and about 30 participants.

Origins of the rabies viruses associated with an outbreak in Newfoundland during 2002-2003.

PubMed

Nadin-Davis, Susan; Muldoon, Frances; Whitney, Hugh; Wandeler, Alexander I

2008-01-01

After being free of rabies of terrestrial mammals since 1988, an outbreak of rabies occurred on the Island of Newfoundland in December 2002 and continued into the middle of 2003. Twenty-one cases, all due to the arctic fox strain of rabies virus, were reported. To explore the immediate origins of this outbreak, viruses from the Newfoundland epizootic were genetically compared to two other rabies viruses recovered in mid-2002 from Cartwright, a mainland coastal community near the Island. While all Island isolates from the 2002-03 outbreak were genetically very similar, consistent with a single introduction from the mainland, they were phylogenetically quite distant from the two samples from Cartwright. A broader-based study examined the relationships between the Island viruses and arctic fox strain viruses originating from across Canada over a period of 14 yr. This analysis indicated that the Newfoundland outbreak viruses were most similar to a variant identified in Labrador in 2004 but also widely distributed in northern Quebec both before and after the Newfoundland incursion. The eastern coastline of mainland Labrador has harbored a particularly large number of variants during the study period, some of which have not been detected elsewhere. A small number of Greenland isolates included in this study were dispersed within the clades of the Canadian samples rather than forming a discrete cluster, an observation that may underline the relative ease of movement of the rabies arctic lineage between these two countries as a result of animal movements over pack ice.

Erosion and deterioration of Isles Dernieres Barrier Island arc, Louisiana: 1842-1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

McBride, R.A.; Westphal, K.; Penland, S.

1989-09-01

The Isles Dernieres barrier island arc is the most rapidly eroding coastline in the US. Located on the Mississippi River delta plain in Terrebonne Parish, Louisiana, the Isles Dernieres consists of four smaller islands in a 32-km long chain. From west to east, these islands are known as Raccoon Island, Whiskey Island, Trinity Island, and East Island. The barrier island arc is separated from the mainland by Caillou Bay, Boca Caillou, and Lake Pelto lagoonal systems. The abandonment and transgression of the Bayou Petit Caillou delta (part of the larger Lafourche delta complex) over the last 600 years, along withmore » sea level rise, repeated storm impacts, and rapid shoreface erosion, have led to the formation of the Isles Dernieres. Continued transgressive submergence combined with a diminishing sediment supply are driving the extreme coastal erosion found in the Isles Dernieres.« less

Tidal flat sedimentation during the last millennium in the northern area of Tidra Island, Banc d’Arguin, Mauritania

NASA Astrophysics Data System (ADS)

Proske, Ulrike; Hanebuth, Till J. J.; Meggers, Helge; Leroy, Suzanne A. G.

2008-01-01

The area around the Tidra Island is a complex and highly dynamic clastic tidal flat system. The character of the northern part of this area is outlined, together with its sedimentary changes through time and the different depositional environments that shaped this coastal area in the last centuries are reconstructed. The multi-proxy approach together with 14C-dating has led to the identification of four main types of deposits using the modern facies distribution as an analogue: A ˜800-440 cal yr BP old sandy shoreface, different types of tidal flats (sand to mudflat) that discontinuously developed on top of this older shoreface deposit, seagrass stands in the most recent part of the sedimentary succession and at least two storm deposits of various ages within the record. The interpretation of the cores' highly non-continuous succession allows the postulation of a constructive sandy shoreface that covered large parts of the area. The in most cases erosive boundary between this older deposit and the overlying tidal flat deposits indicates that a short-lived event eroded parts of this sandy shoreface deposit. According to the latest studies, recent sea-level fluctuations can be excluded so it is suggested that a major storm event eroded parts of the sandy shoreface to about 2-2.5 m below the modern mean low water. This erosive storm event possibly produced accommodation space in the water column for the renewed accumulation of sediments so that tidal flat sediments could evolve on top of the sandy shoreface deposits. At least one other storm event led to further reshaping of the area and finally the modern tidal flats and seagrass stands in the proximity of Tidra Island formed. As shown in current research [e.g. Barusseau, J.P., Vernet, R., Saliège, J.F., Descamps, C., 2007. Late Holocene sedimentary forcing and human settlements in the Jerf el Oustani - Ras el Sass region (Banc d'Arguin, Mauritania). Geomorphologie-Relief Processus Environnement 1, 7-18], these observations are in contrast to the overall constructive coastline evolution the Golfe d'Arguin. This is probably linked to the exceptional position of the Tidra Island area that represents a morphological protrusion in the coastline and is thus also exposed to erosive processes rather than sediment accumulation.

Methane Ebullition During Simulated Lake Expansion and Permafrost Degradation

NASA Astrophysics Data System (ADS)

Mazéas, O.; von Fischer, J. C.; Whelan, M.; Rhew, R.

2007-12-01

Methane, a potent greenhouse gas, is emitted by Arctic tundra and lakes. Ebullition, or bubbling, of methane from Arctic lakes has been shown to be a major transport mechanism from the sediment to the atmosphere, and ebullition rates are greatest near the edges of the lakes where active erosion is occurring. In regions of continuous permafrost, Arctic lakes have been expanding in recent decades, attributed to permafrost melting and development of thermokarst. Lake expansion occurs when the margins erode into water, supplying large amounts of organic rich material to the sediment-water interface. This allows carbon that was previously stored in the soil (active layer and permafrost) to become bioavailable and subject to decomposition. An increase in Arctic methane emissions as a result of permafrost thawing and lake expansion would constitute a positive feedback to Arctic warming. In order to better understand these processes, an experiment was initiated in July 2007 at the Barrow Environmental Observatory, Barrow, AK. Different layers of locally collected tundra soil were placed into incubation chambers at the bottom of a shallow (about 1 m deep) lake. Each experimental chamber consists of a bucket fixed underneath an inverted funnel, with a sampling port on top to capture and collect the emitted gases. Gas samples are analyzed for methane and carbon dioxide concentrations, as well as relevant isotopic compositions. Gas sampling has occurred at frequent intervals during the late summer and will continue through the early winter. Three replicates of each layer (active layer, seasonally frozen active layer and permafrost) were incubated, as well as an empty control chamber. An additional chamber containing thawed permafrost and cellulose-rich sawdust was placed for comparison, as cellulose is a major component of plant tissue and the fermentation of the cellulose should yield substrates for methanogenesis. Total production of methane versus organic carbon content of initial sample, kinetics of ebullition, and relative potential emissions from each tundra layer will be assessed.

Impacts of shore expansion and catchment characteristics on lacustrine thermokarst records in permafrost lowlands, Alaska Arctic Coastal Plain

USGS Publications Warehouse

Lenz, Josefine; Jones, Benjamin M.; Wetterich, Sebastian; Tjallingii, Rik; Fritz, Michael; Arp, Christopher D.; Rudaya, Natalia; Grosse, Guido

2016-01-01

Arctic lowland landscapes have been modified by thermokarst lake processes throughout the Holocene. Thermokarst lakes form as a result of ice-rich permafrost degradation, and they may expand over time through thermal and mechanical shoreline erosion. We studied proximal and distal sedimentary records from a thermokarst lake located on the Arctic Coastal Plain of northern Alaska to reconstruct the impact of catchment dynamics and morphology on the lacustrine depositional environment and to quantify carbon accumulation in thermokarst lake sediments. Short cores were collected for analysis of pollen, sedimentological, and geochemical proxies. Radiocarbon and 210Pb/137Cs dating, as well as extrapolation of measured historic lake expansion rates, were applied to estimate a minimum lake age of ~1400 calendar years BP. The pollen record is in agreement with the young lake age as it does not include evidence of the “alder high” that occurred in the region ~4000 cal yr BP. The lake most likely initiated from a remnant pond in a drained thermokarst lake basin (DTLB) and deepened rapidly as evidenced by accumulation of laminated sediments. Increasing oxygenation of the water column as shown by higher Fe/Ti and Fe/S ratios in the sediment indicate shifts in ice regime with increasing water depth. More recently, the sediment source changed as the thermokarst lake expanded through lateral permafrost degradation, alternating from redeposited DTLB sediments, to increased amounts of sediment from eroding, older upland deposits, followed by a more balanced combination of both DTLB and upland sources. The characterizing shifts in sediment sources and depositional regimes in expanding thermokarst lakes were, therefore, archived in the thermokarst lake sedimentary record. This study also highlights the potential for Arctic lakes to recycle old carbon from thawing permafrost and thermokarst processes.

Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

PubMed

Lanier, Hayley C; Gunderson, Aren M; Weksler, Marcelo; Fedorov, Vadim B; Olson, Link E

2015-01-01

Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of biodiversity.

Comparative Phylogeography Highlights the Double-Edged Sword of Climate Change Faced by Arctic- and Alpine-Adapted Mammals

PubMed Central

Lanier, Hayley C.; Gunderson, Aren M.; Weksler, Marcelo; Fedorov, Vadim B.; Olson, Link E.

2015-01-01

Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of biodiversity. PMID:25734275

The Fate and Stability of Eroding Wetland Soil Carbon in a Subsiding Deltaic Coastal Plain

NASA Astrophysics Data System (ADS)

White, J. R.; Steinmuller, H.; Chambers, L. G.; Fontenot, A.

2017-12-01

Coastal wetlands can respond to rapid rates of relative sea level rise via wetland submergence and/or erosion, which occur when wetlands are unable to vertically accrete to keep pace with sea level rise. As coastal wetlands erode, previously sequestered organic carbon is exposed to oxygen-rich estuarine water. This transition in redox from anaerobic to aerobic condition can trigger increased mineralization rates of decades to centuries'-old soil carbon. Barataria Bay, Louisiana has one of the highest coastal wetland land loss rates in the United States, primarily due to eustatic sea level rise coupled with coastal subsidence. Marsh-edge erosion rates measured over the past two years are on the order of 1.5 meters per year. Meter long soil cores were obtained from vegetated wetland sites and sectioned into 11 intervals to investigate aerobic and anaerobic mineralization rates with depth. In surface soils, organic carbon mineralization rates averaged 16 times greater than anaerobic mineralization rates. In deeper, older soils, the aerobic mineralization rate was still an order of magnitude greater than the anaerobic rate, suggesting a significant portion of this older, soil carbon is readily cycling back to the atmosphere after erosion followed by mineralization by microorganisms. These results have consequences for increased atmospheric CO2 concentrations in the future, as stable coastlines worldwide will be subjected to Barataria-bay levels of sea level rise in the next 50-75 years.

An Integrated Bathymetric and Topographic Digital Terrain Model of the Canadian Arctic Archipelago

NASA Astrophysics Data System (ADS)

Alm, G.; Macnab, R.; Jakobsson, M.; Kleman, J.; McCracken, M.

2002-12-01

Currently, the International Bathymetric Chart of the Arctic Ocean (IBCAO) [Jakobsson et al. 2000], contains the most up-to-date digital bathymetric model of the entire Canadian Arctic Archipelago. IBCAO is a seamless bathymetric/topographic Digital Terrain Model (DTM) that incorporates three primary data sets: all available bathymetric data at the time of compilation; the US Geological Survey GTOPO30 topographic data; and the World Vector Shoreline for coastline representation. The horizontal grid cell size is 2.5 x 2.5 km on a Polar Stereographic projection, which is adequate for regional visualization and analysis, but which may not be sufficient for certain geoscientific and oceanographic applications. However, the database that was constructed during the IBCAO project holds bathymetric data of a high quality throughout most of the Canadian Arctic Archipelago, justifying a compilation resolution that is better than 2.5 x 2.5 km. This data is primarily from historical hydrographic surveys that were carried out by the Canadian Hydrographic Survey (CHS). The construction of a higher resolution bathymetry/topography DTM of the Canadian Arctic Archipelago (complete with an error estimation of interpolated grid cells) requires a consideration of historical metadata which contains detailed descriptions of horizontal and vertical datums, positioning systems, and the depth sounding systems that were deployed during individual surveys. A significant portion of this metadata does not exist in digital form; it was not available during the IBCAO compilation, although due to the relatively low resolution of the original DTM (2.5 x 2.5 km), its absence was considered a lesser problem. We have performed "data detective" work and have extracted some of the more crucial metadata from CHS archives and are thus able to present a preliminary version of a seamless Digital Terrain Model of the Canadian Arctic Archipelago. This represents a significant improvement over the original IBCAO DTM in this area. The use of a merged seamless bathymetry/topography model substantially facilitates the overlay and incorporation of other spatially referenced geological and geophysical datasets. For example, one intended use of the model is to merge the results from the mapping of regional glacial morphology features, in order to further address the glacial history of the region. Jakobsson, M., Cherkis, N., Woodward, J., Coakley, B., and Macnab, R., 2000, A new grid of Arctic bathymetry: A significant resource for scientists and mapmakers, EOS Transactions, American Geophysical Union, v. 81, no. 9, p. 89, 93, 96.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbott, Benjamin; Jones, Jeremy B.; Schuur, Edward A.

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climatemore » change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced.« less

Observing Muostakh Island disappear: erosion of a ground-ice-rich coast in response to summer warming and sea ice reduction on the East Siberian shelf

NASA Astrophysics Data System (ADS)

Günther, F.; Overduin, P. P.; Baranskaya, A.; Opel, T.; Grigoriev, M. N.

2013-08-01

Observations of coastline retreat using contemporary very high resolution satellite and historical aerial imagery were compared to measurements of open water fractions and summer air temperatures. We analyzed seasonal and interannual variations of thawing-induced cliff top retreat (thermo-denudation) and marine abrasion (thermo-abrasion) on Muostakh Island in the southern central Laptev Sea. The island is composed of ground-ice-rich permafrost deposits of Ice Complex type that render it particularly susceptible to erosion along the coast, resulting in land loss. Based on topographic reference measurements during field campaigns, we generated digital elevation models using stereophotogrammetry, in order to block adjust and ortho-rectify aerial photographies from 1951 and GeoEye, QuickBird, WorldView-1, and WorldView-2 imagery from 2010 to 2012 for change detection. Coastline retreat for erosive segments ranged from -13 to -585 m and was -109 ± 81 m (-1.8 ± 1.3 m a-1) on average during the historical period. Current seasonal dynamics of cliff top retreat revealed rapid thermo-denudation rates of -10.2 ± 4.5 m a-1 in mid summer and -4.1 ± 2.0 m a-1 on average during the 2010-2012 observation period. Using sea ice concentration data from the Special Sensor Microwave Imager (SSM/I) and air temperature time series from Tiksi, we calculated seasonal duration available for thermo-abrasion, expressed as open water days, and for thermo-denudation, based on thawing degree days. Geomorphometric analysis revealed that total ground ice content on Muostakh is made up of equal amounts of intrasedimentary and macro ground ice, while its vertical hourglass distribution provides favorable local preconditions for subsidence and the acceleration of coastal thermo-erosion under intensifying environmental forcings. Our results showed a~close relationship between mean summer air temperature and coastal thermo-erosion rates, in agreement with observations made for various permafrost coastlines different from East Siberian Ice Complex coasts elsewhere in the Arctic. Seasonality and recent interannual variations of coastline retreat rates suggest that the combination of macro ground ice distribution in the ground and changes in enviromental forcing generate a cyclicity in coastal thermo-erosion, that is currently increasing in frequency.

A model integrating longshore and cross-shore processes for predicting long-term shoreline response to climate change

USGS Publications Warehouse

Vitousek, Sean; Barnard, Patrick; Limber, Patrick W.; Erikson, Li; Cole, Blake

2017-01-01

We present a shoreline change model for coastal hazard assessment and management planning. The model, CoSMoS-COAST (Coastal One-line Assimilated Simulation Tool), is a transect-based, one-line model that predicts short-term and long-term shoreline response to climate change in the 21st century. The proposed model represents a novel, modular synthesis of process-based models of coastline evolution due to longshore and cross-shore transport by waves and sea-level rise. Additionally, the model uses an extended Kalman filter for data assimilation of historical shoreline positions to improve estimates of model parameters and thereby improve confidence in long-term predictions. We apply CoSMoS-COAST to simulate sandy shoreline evolution along 500 km of coastline in Southern California, which hosts complex mixtures of beach settings variably backed by dunes, bluffs, cliffs, estuaries, river mouths, and urban infrastructure, providing applicability of the model to virtually any coastal setting. Aided by data assimilation, the model is able to reproduce the observed signal of seasonal shoreline change for the hindcast period of 1995-2010, showing excellent agreement between modeled and observed beach states. The skill of the model during the hindcast period improves confidence in the model's predictive capability when applied to the forecast period (2010-2100) driven by GCM-projected wave and sea-level conditions. Predictions of shoreline change with limited human intervention indicate that 31% to 67% of Southern California beaches may become completely eroded by 2100 under sea-level rise scenarios of 0.93 to 2.0 m.

From grey to green: Efficacy of eco-engineering solutions for nature-based coastal defence.

PubMed

Morris, Rebecca L; Konlechner, Teresa M; Ghisalberti, Marco; Swearer, Stephen E

2018-05-01

Climate change is increasing the threat of erosion and flooding along coastlines globally. Engineering solutions (e.g. seawalls and breakwaters) in response to protecting coastal communities and associated infrastructure are increasingly becoming economically and ecologically unsustainable. This has led to recommendations to create or restore natural habitats, such as sand dunes, saltmarsh, mangroves, seagrass and kelp beds, and coral and shellfish reefs, to provide coastal protection in place of (or to complement) artificial structures. Coastal managers are frequently faced with the problem of an eroding coastline, which requires a decision on what mitigation options are most appropriate to implement. A barrier to uptake of nature-based coastal defence is stringent evaluation of the effectiveness in comparison to artificial protection structures. Here, we assess the current evidence for the efficacy of nature-based vs. artificial coastal protection and discuss future research needs. Future projects should evaluate habitats created or restored for coastal defence for cost-effectiveness in comparison to an artificial structure under the same environmental conditions. Cost-benefit analyses should take into consideration all ecosystem services provided by nature-based or artificial structures in addition to coastal protection. Interdisciplinary research among scientists, coastal managers and engineers is required to facilitate the experimental trials needed to test the value of these shoreline protection schemes, in order to support their use as alternatives to artificial structures. This research needs to happen now as our rapidly changing climate requires new and innovative solutions to reduce the vulnerability of coastal communities to an increasingly uncertain future. © 2018 John Wiley & Sons Ltd.

A model integrating longshore and cross-shore processes for predicting long-term shoreline response to climate change

NASA Astrophysics Data System (ADS)

Vitousek, Sean; Barnard, Patrick L.; Limber, Patrick; Erikson, Li; Cole, Blake

2017-04-01

We present a shoreline change model for coastal hazard assessment and management planning. The model, CoSMoS-COAST (Coastal One-line Assimilated Simulation Tool), is a transect-based, one-line model that predicts short-term and long-term shoreline response to climate change in the 21st century. The proposed model represents a novel, modular synthesis of process-based models of coastline evolution due to longshore and cross-shore transport by waves and sea level rise. Additionally, the model uses an extended Kalman filter for data assimilation of historical shoreline positions to improve estimates of model parameters and thereby improve confidence in long-term predictions. We apply CoSMoS-COAST to simulate sandy shoreline evolution along 500 km of coastline in Southern California, which hosts complex mixtures of beach settings variably backed by dunes, bluffs, cliffs, estuaries, river mouths, and urban infrastructure, providing applicability of the model to virtually any coastal setting. Aided by data assimilation, the model is able to reproduce the observed signal of seasonal shoreline change for the hindcast period of 1995-2010, showing excellent agreement between modeled and observed beach states. The skill of the model during the hindcast period improves confidence in the model's predictive capability when applied to the forecast period (2010-2100) driven by GCM-projected wave and sea level conditions. Predictions of shoreline change with limited human intervention indicate that 31% to 67% of Southern California beaches may become completely eroded by 2100 under sea level rise scenarios of 0.93 to 2.0 m.

USGS science for the Nation's changing coasts; shoreline change assessment

USGS Publications Warehouse

Thieler, E. Robert; Hapke, Cheryl J.

2011-01-01

The coastline of the United States features some of the most popular tourist and recreational destinations in the world and is the site of intense residential, commercial, and industrial development. The coastal zone also has extensive and pristine natural areas, with diverse ecosystems providing essential habitat and resources that support wildlife, fish, and human use. Coastal erosion is a widespread process along most open-ocean shores of the United States that affects both developed and natural coastlines. As the coast changes, there are a wide range of ways that change can affect coastal communities, habitats, and the physical characteristics of the coast?including beach erosion, shoreline retreat, land loss, and damage to infrastructure. Global climate change will likely increase the rate of coastal change. A recent study of the U.S. Mid-Atlantic coast, for example, found that it is virtually certain that sandy beaches will erode faster in the future as sea level rises because of climate change. The U.S. Geological Survey (USGS) is responsible for conducting research on coastal change hazards, understanding the processes that cause coastal change, and developing models to predict future change. To understand and adapt to shoreline change, accurate information regarding the past and present configurations of the shoreline is essential. A comprehensive, nationally consistent analysis of shoreline movement is needed. To meet this national need, the USGS is conducting an analysis of historical shoreline changes along open-ocean coasts of the conterminous United States and parts of Alaska and Hawaii, as well as the coasts of the Great Lakes.

Connecting Indigenous Knowledge to Thaw Lake Cycle Research on the Arctic Coastal Plain of Alaska

NASA Astrophysics Data System (ADS)

Eisner, W. R.; Cuomo, C. J.; Hinkel, K. M.; Jones, B. M.; Hurd, J.

2005-12-01

Thaw lakes cover about 20% of the Arctic Coastal Plain of Alaska. Another 26% is scarred by basins that form when lakes drain, and these drained thaw-lake basins are sites for preferential carbon accumulation as plant biomass. Recent studies in the continuous permafrost zone of Western Siberia suggest that lakes have been expanding in the past several decades in response to regional warming. Anticipated regional warming would likely mobilize sequestered soil organic carbon, resulting in the emission of CO2 and CH4. Our understanding of the processes leading to thaw lake formation, expansion, and drainage in northern Alaska has been limited because models are specific to the flat, young Outer (seaward) Coastal Plain comprising 1/3 of the region. Furthermore, spatial and temporal analysis of lake dynamics is largely restricted to the period since 1948, when aerial photographs first became available across large regions of the Coastal Plain. In order to fill these gaps, we have been interviewing Iñupiaq elders, hunters, and berry pickers from the villages of Atqasuk and Barrow. The objective of these interviews is to obtain accounts of lake formation, expansion and drainage that have occurred within living or oral memory, and extend the record back several generations. To date, we have interviewed fifteen Iñupiat; most of these are people who travel the tundra frequently and have done so for decades. They have first-hand experience of lake drainage, sea cliff and river bank erosion, permafrost degradation, and other landscape changes. Many informants expressed concern that landscape changes are occurring at an increasingly rapid rate. They have identified lakes that have drained, areas where the permafrost is thawing, and places where the sea and river coastline is eroding. We have been able to corroborate reports of lake drainage from our informants with a series of aerial photographs, satellite images, and radiocarbon dates. In many instances, the elders have pinpointed the year of drainage where we previously had only bracketed a 5-10 year period in which drainage must have occurred. Our informants were also often able to identify the cause of the drainage event, the process by which it occurred, and the aftermath of the event (i.e. overflow into other lakes, changes in stream hydrology, changes in fish species, etc.). We have also noted a difference in the reports of lake drainage and other landscape changes between the people who have more knowledge of the Inner (Atqasuk residents) and Outer (Barrow residents) Coastal Plain. Travelers of the Outer Coastal Plain have identified more lake drainage events. The people of the Inner Coastal Plain, conversely, speak of lower water levels in lakes and overall drier conditions in recent years. The quantity of information from the Barrow and Atqasuk elders and the precision of their observations is impressive. We will be analyzing, by both quantitative and qualitative methods, this information in conjunction with our ongoing studies of thaw-lake processes on the Arctic Coastal Plain. In addition to discussing specific knowledge about thaw-lake processes, we are archiving the range of knowledge and stories that elders, hunters, and other users of the tundra introduce to the interviews. We believe the traditional knowledge and ongoing observations of the Iñupiat are highly valuable to scientists and society in general, and we strongly advocate further cooperation between traditional and scientific "ways of knowing."

Stratigraphy and evolution of emerged Pleistocene reefs at the Red Sea coast of Sudan

NASA Astrophysics Data System (ADS)

Hamed, Basher; Bussert, Robert; Dominik, Wilhelm

2016-02-01

Emerged Pleistocene coral reefs constitute a prominent landform along the Red Sea coast of Sudan. They are well exposed with a thickness of up to 12 m and extend over a width of about 3 km parallel to the coastline. Four major reef units that represent different reef zones are distinguished. Unit 1 is located directly at the coastline and is assigned to the rock-reef rim, while unit 2 represents the reef-front zone. Unit 3 is attributed to the reef-flat zone and unit 4 to the back-reef zone. The stratigraphic position and age of the four units respectively the facies zones are based on field relationships and δ18O analysis. Results of δ18O analysis of coral, gastropod and bivalve samples were correlated to previous age dating of correlative reefs in Sudan and other parts of the Red Sea region. Estimation of reef ages was mainly based on δ18O values of the reef-front zone (unit 2) and the observed sedimentary succession of the reefs. δ18O values of two Porites coral samples from the reef-front zone strongly suggest equivalent ages of 120 and 122 ka that correspond to marine isotope stage MIS 5.5. Based on δ18O values and the field relationship to the reef-front zone, ages of reef-flat zone (unit 3) and back-reef zone (unit 4) could be assigned to MIS 9 and MIS 7 respectively. MIS 5.1 is suggested for the reef-rock rim (unit 1). The relationship of the reef zones to individual MIS might be explained by the predominance of a specific zone during a certain stage, while other facies were less well developed and/or later eroded by wave action. The reef unit most distal from the recent coastline formed during interglacial stage MIS 7, while former studies assign this unit to interglacial stage MIS 9. Unique flourishing, high diversity and excellent preservation of corals in the back-reef unit of MIS 7 reflect growth in troughs landward of the oldest reef-flat formed during previous interglacial stage MIS 9.

Assessing the role of Climate Variability in the recent evolution of coastlines in southern Italy

NASA Astrophysics Data System (ADS)

Di Paola, Gianluigi; Atkinson, David; Rosskopf, Carmen M.; Walker, Ian

2016-04-01

During the last century, Climatic Variability (CV) and change effects have generated a discernable impact on the world's coasts, most notably through changes in the frequency and/or magnitude of storm surges, flooding, coastal erosion and sea-level rise. This study explores CV signals and coastal responses along a 36 km stretch of coast in the Molise region of southern Italy on the Central Adriatic Sea. Two dominant signals of CV in the Mediterranean region of Europe are characterized by the North Atlantic Oscillation (NAO) and the East Atlantic-West Russia (EAWR) patterns. The NAO is the leading mode of CV in the North Atlantic region and periods with positive NAO index values are typically associated with above average wind speeds across the mid-latitudes of the Atlantic and western Europe, with anomalously northerly flows across the Mediterranean region and enhanced trade winds over the sub-tropical North Atlantic. Although NAO is one of the most prominent patterns in all seasons, its relative role in regulating the variability of the European climate during non-winter months is not as clear as for the winter season. In contrast, the EAWR exerts strong influence on precipitation in the Mediterranean region such that, during the negative phase of EAWR, wetter conditions prevail across central Europe and the Mediterranean region, with precipitation extremes often occurring during these periods. This study examines the effects of NAO and EAWR on coastline response in the Molise region, which has a microtidal regime (ordinary tidal excursions of 30-40 cm). GIS analysis of shoreline changes from historical aerial photography from 1954-2011 was performed and 20 years (1989-2008) of wave data were analysed from the nearby Ortona buoy to define trends and extreme event occurrence in the wave climate in the study area. Finally, statistical associations between NAO, EAWR, and other CV indices of possible influence (e.g. Arctic Oscillation, Scandinavia Pattern, or the East Atlantic pattern) and shoreline position changes were explored in order to identify linkages between CV forcing and coastal response in this region. The study demonstrates that the recent evolution of the Molise coastline is responding to changes in the wave climate and increases in the frequency and intensity of storm surges in recent years. Coastal response in the region is also strongly controlled by engineering interventions, such as backwater structures and groynes (almost the 75% of coastline is characterized by offshore defenses, above all around Biferno and Trigno mouths and Termoli harbor), and the interaction of the river systems that feed the coastline. This condition may mitigate some of the impacts of CV events that are observed elsewhere along intervening stretches of coast.

The contaminant legacy from historic coastal landfills and their potential as sources of diffuse pollution.

PubMed

O'Shea, Francis T; Cundy, Andrew B; Spencer, Kate L

2018-03-01

Prior to modern environmental regulation landfills in low-lying coastal environments were frequently constructed without leachate control, relying on natural attenuation within inter-tidal sediments to dilute and disperse contaminants reducing environmental impact. With sea level rise and coastal erosion these sites may now pose a pollution risk, yet have received little investigation. This work examines the extent of metal contamination in saltmarsh sediments surrounding a historic landfill in the UK. Patterns of sediment metal data suggest typical anthropogenic pollution chronologies for saltmarsh sediments in industrialised nations. However, many metals were also enriched at depth in close proximity to the landfill boundary and are indicative of a historical leachate plume. Though this total metal load is low, e.g., c. 1200 and 1650kg Pb and Zn respectively, with >1000 historic landfills on flood risk or eroding coastlines in the UK this could represent a significant, yet under-investigated, source of diffuse pollution. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Minimal erosion of Arctic alpine topography during late Quaternary glaciation

NASA Astrophysics Data System (ADS)

Gjermundsen, Endre F.; Briner, Jason P.; Akçar, Naki; Foros, Jørn; Kubik, Peter W.; Salvigsen, Otto; Hormes, Anne

2015-10-01

The alpine topography observed in many mountainous regions is thought to have formed during repeated glaciations of the Quaternary period. Before this time, landscapes had much less relief. However, the spatial patterns and rates of Quaternary exhumation at high latitudes--where cold-based glaciers may protect rather than erode landscapes--are not fully quantified. Here we determine the exposure and burial histories of rock samples from eight summits of steep alpine peaks in northwestern Svalbard (79.5° N) using analyses of 10Be and 26Al concentrations. We find that the summits have been preserved for at least the past one million years. The antiquity of Svalbard’s alpine landscape is supported by the preservation of sediments older than one million years along a fjord valley, which suggests that both mountain summits and low-elevation landscapes experienced very low erosion rates over the past million years. Our findings support the establishment of northwestern Svalbard’s alpine topography during the early Quaternary. We suggest that, as the Quaternary ice age progressed, glacial erosion in the Arctic became inefficient and confined to ice streams, and high-relief alpine landscapes were preserved by minimally erosive glacier armour.

CMIP5-based global wave climate projections including the entire Arctic Ocean

NASA Astrophysics Data System (ADS)

Casas-Prat, M.; Wang, X. L.; Swart, N.

2018-03-01

This study presents simulations of the global ocean wave climate corresponding to the surface winds and sea ice concentrations as simulated by five CMIP5 (Coupled Model Intercomparison Project Phase 5) climate models for the historical (1979-2005) and RCP8.5 scenario future (2081-2100) periods. To tackle the numerical complexities associated with the inclusion of the North Pole, the WAVEWATCH III (WW3) wave model was used with a customized unstructured Spherical Multi-Cell grid of ∼100 km offshore and ∼50 km along coastlines. The climate model simulated wind and sea ice data, and the corresponding WW3 simulated wave data, were evaluated against reanalysis and hindcast data. The results show that all the five sets of wave simulations projected lower waves in the North Atlantic, corresponding to decreased surface wind speeds there in the warmer climate. The selected CMIP5 models also consistently projected an increase in the surface wind speed in the Southern Hemisphere (SH) mid-high latitudes, which translates in an increase in the WW3 simulated significant wave height (Hs) there. The higher waves are accompanied with increased peak wave period and increased wave age in the East Pacific and Indian Oceans, and a significant counterclockwise rotation in the mean wave direction in the Southern Oceans. The latter is caused by more intense waves from the SH traveling equatorward and developing into swells. Future wave climate in the Arctic Ocean in summer is projected to be predominantly of mixed sea states, with the climatological mean of September maximum Hs ranging mostly 3-4 m. The new waves approaching Arctic coasts will be less fetch-limited as ice retreats since a predominantly southwards mean wave direction is projected in the surrounding seas.

Study of Heavy Metals in a Wetland Area Adjacent to a Waste Disposal Site Near Resolute Bay, Canadian High Arctic

NASA Astrophysics Data System (ADS)

Lund, K. E.; Young, K. L.

2004-05-01

Heavy metal contamination in High Arctic systems is of growing concern. Studies have been conducted measuring long range and large point source pollutants, but little research has been done on small point sources such as municipal waste disposal sites. Many Arctic communities are coastal, and local people consume marine wildlife in which concentrations of heavy metals can accumulate. Waste disposal sites are often located in very close proximity to the coastline and leaching of these metals could contaminate food sources on a local scale. Cadmium and lead are the metals focussed on by this study, as the Northern Contaminants Program recognizes them as metals of concern. During the summer of 2003 a study was conducted near Resolute, Nunavut, Canada, to determine the extent of cadmium and lead leaching from a local dumpsite to an adjacent wetland. The ultimate fate of these contaminants is approximately 1 km downslope in the ocean. Transects covering an area of 0.3 km2 were established downslope from the point of disposal and water and soil samples were collected and analyzed for cadmium and lead. Only trace amounts of cadmium and lead were found in the water samples. In the soil samples, low uniform concentrations of cadmium were found that were slightly above background levels, except for adjacent to the point of waste input where higher concentrations were found. Lead soil concentrations were higher than cadmium and varied spatially with soil material and moisture. Overall, excessive amounts of cadmium and lead contamination do not appear to be entering the marine ecosystem. However, soil material and moisture should be considered when establishing waste disposal sites in the far north

Sources, degradation and transport of terrigenous organic carbon on the East Siberian Arctic Shelf Seas

NASA Astrophysics Data System (ADS)

Tesi, Tommaso; Semiletov, Igor; Dudarev, Oleg; Gustafsson, Örjan

2013-04-01

Recent studies suggest that the present hydrological regime increase observed in the Arctic rivers is mainly the consequence of the changes in permafrost conditions as a result of climate warming. Given the enormous amount of carbon stored in coastal and terrestrial permafrost the potentially increased supply from this large carbon pool to the coastal Arctic Ocean, possibly associated with a translocated release to the atmosphere as CO2, is considered a plausible scenario in a warming climate. However, there is not sufficient information regarding the reactivity of terrigenous material once supplied to the Arctic Ocean. In this study, we address this critical issue by examining the organic composition of surface sediments collected over extensive scales on the East Siberian Arctic Shelf (ESAS) as part of the International Siberian Shelf Study (ISSS). The ESAS represents by far the largest shelf of the Arctic Ocean. Samples were collected from the inner- to the outer-shelf following the sediment transport pathway in a region between the Lena and the Kolyma rivers. The analytical approach includes the characterization of marine and land-derived carbon using a large number of molecular biomarkers obtained by alkaline CuO oxidation such as lignin-phenols, cutin-derived products, p-hydroxy benzenes, benzoic acids, fatty acids, and dicarboxylic acids. Our results indicated high concentrations of terrigenous material in shallow sediments and a marked decrease of terrestrial biomarkers with increasing distance from the coastline. In parallel, lignin-based degradation proxies suggested highly altered terrigenous carbon in mid- and outer-shelf sediments compared to coastal sediments. Furthermore, the ratio of cutin-derived products over lignin significantly increased along the sediment transport pathway. Considering that cutin is considered to be intrinsically more reactive compared to lignin, high values of this ratio off the coastal region were interpreted as selective transport of fine sediments relatively rich in cutin. Finally, in addition to degradation and sorting processes, our results indicated dilution of land-derived material with marine phytodetritus with increasing distance from the shore. Results from our study indicate that the benthic sediment transport system in the ESAS is quite dynamic and acts as an efficient incinerator of terrigenous material as observed in mid-latitude settings. Therefore, considering the mega-pool of terrigenous carbon susceptible to remobilization because of climate-induced changes, our results suggest future limited burial of this material in mid- and outer-shelf deposits.

Oblique Aerial Photography of the Arctic Coast of Alaska, Nulavik to Demarcation Point, August 7-10, 2006

USGS Publications Warehouse

Gibbs, Ann E.; Richmond, Bruce M.

2009-01-01

The Arctic Coastal Plain of northern Alaska, an area of strategic economic importance to the United States, is home to remote Native American communities and encompasses unique habitats of global significance. Coastal erosion along the Arctic coast is chronic and widespread; recent evidence suggests that erosion rates are among the highest in the world (up to ~16 m/yr) and may be accelerating. Coastal erosion adversely impacts energy-related infrastructure, natural shoreline habitats, and Native American communities. Climate change is thought to be a key component of recent environmental changes in the Arctic. Reduced sea-ice cover in the Arctic Ocean is one of the probable mechanisms responsible for increasing coastal exposure to wave attack and the resulting increase in erosion. Extended periods of permafrost melting and associated decrease in bluff cohesion and stability are another possible source of the increase in erosion. Several studies of selected areas on the Alaska coast document past shoreline positions and coastal change, but none have examined the entire North coast systematically. Results from these studies indicate high rates of coastal retreat that vary spatially along the coast. To address the need for a comprehensive and regionally consistent evaluation of shoreline change along the North coast of Alaska, the U.S. Geological Survey (USGS), as part of their Coastal and Marine Geology Program's (CMGP) National Assessment of Shoreline Change Study, is evaluating shoreline change from Peard Bay to the United States/Canadian border, using historical maps and photography and a standardized methodology that is consistent with other shoreline-change studies along the Nation's coastlines (for example, URL http://coastal.er.usgs.gov/shoreline-change/ (last accessed March 2, 2009). This report contains photographs collected during an aerial-reconnaissance survey conducted in support of this study. An accompanying ESRI ArcGIS shape file (and plain-text copy) indicates the position of the aircraft and time when each photograph was taken. The USGS-CMGP Field Activity ID for the survey is A-1-06-AK, and more information on the survey and how to view the photographs using Google Earth software is available online at: URL http://walrus.wr.usgs.gov/infobank/a/a106ak/html/a-1-06-ak.meta.html (last accessed March 2, 2009).

Nearshore Circulation and Storm Surge Along the Mackenzie Delta Coast

NASA Astrophysics Data System (ADS)

Perrie, W.; Mulligan, R. P.; Solomon, S. M.; Hoque, A.; Zhang, L.

2008-12-01

The Mackenzie Delta is a 150 km long section of coastline characterized by muddy sediments where the Mackenzie River outflow, dispersed over 20 distributary channels, discharges into the southern Beaufort Sea. The marine environment in this region is an important and integral part of the lives of Canadian Northerners. The area is also undergoing hydrocarbon exploration with potential development within the next decade. Changes to Arctic climate, such as increasing ice-free western Arctic Ocean and intensifying storm activity, may endanger the coastal settlements and marine environment in the Mackenzie Delta region. The low gradient of the delta and the adjacent inner shelf makes it very susceptible to flooding during storms. Field observations in the nearshore zone collected in August of 2007 and 2008 indicate strong gradients in temperature and salinity in shallow water of 2-6 m. The fluctuations are associated with the movements of warm and fresh river plumes and wind-driven upwelling of cold and saline water below the thermocline. The observations are in agreement with 3D model simulations of the nearshore delta region using Delft3D, which includes wind, tidal, storm surge, buoyancy and river forcing. The results validate the model and indicate that it can be used to hindcast the nearshore oceanographic conditions during severe Arctic storms. As a case study we present preliminary model results for an Arctic storm from late 1999 that caused extensive vegetation die-off in the outer delta. This cyclone was a mesoscale Arctic storm that developed over the NE Pacific and western Bering Sea, intensified explosively in the Gulf of Alaska and developed into a meteorological bomb. The storm made landfall at Cape Newenham, Alaska, crossed the Rocky Mountains to the Yukon and Northwest Territories and re-intensified over a zone of high sea surface temperature gradients in the southern Beaufort Sea. Using the Canadian Mesoscale Compressible Community (MC2) atmospheric model, simulations of the storm pattern, track and intensity are in very good agreement with the NCEP re-analysis. This is model coupled to the Princeton Ocean Model (POM) and Hibler Ice Model, which are used to provide basin-scale driver fields and define the boundary conditions of the nearshore Delft3D model for the Mackenzie Delta region. Coastal damage was predominately caused by storm surge, and the high salinity flood waters that flowed over the surface of the outer delta.

Extracting the information of coastline shape and its multiple representations

NASA Astrophysics Data System (ADS)

Liu, Ying; Li, Shujun; Tian, Zhen; Chen, Huirong

2007-06-01

According to studying the coastline, a new way of multiple representations is put forward in the paper. That is stimulating human thinking way when they generalized, building the appropriate math model and describing the coastline with graphics, extracting all kinds of the coastline shape information. The coastline automatic generalization will be finished based on the knowledge rules and arithmetic operators. Showing the information of coastline shape by building the curve Douglas binary tree, it can reveal the shape character of coastline not only microcosmically but also macroscopically. Extracting the information of coastline concludes the local characteristic point and its orientation, the curve structure and the topology trait. The curve structure can be divided the single curve and the curve cluster. By confirming the knowledge rules of the coastline generalization, the generalized scale and its shape parameter, the coastline automatic generalization model is established finally. The method of the multiple scale representation of coastline in this paper has some strong points. It is human's thinking mode and can keep the nature character of the curve prototype. The binary tree structure can control the coastline comparability, avoid the self-intersect phenomenon and hold the unanimous topology relationship.

Plio-Pleistocene evolution of water mass exchange and erosional input at the Atlantic-Arctic gateway

NASA Astrophysics Data System (ADS)

Teschner, Claudia; Frank, Martin; Haley, Brian A.; Knies, Jochen

2016-05-01

Water mass exchange between the Arctic Ocean and the Norwegian-Greenland Seas has played an important role for the Atlantic thermohaline circulation and Northern Hemisphere climate. We reconstruct past water mass mixing and erosional inputs from the radiogenic isotope compositions of neodymium (Nd), lead (Pb), and strontium (Sr) at Ocean Drilling Program site 911 (leg 151) from 906 m water depth on Yermak Plateau in the Fram Strait over the past 5.2 Myr. The isotopic compositions of past bottom waters were extracted from authigenic oxyhydroxide coatings of the bulk sediments. Neodymium isotope signatures obtained from surface sediments agree well with present-day deepwater ɛNd signature of -11.0 ± 0.2. Prior to 2.7 Ma the Nd and Pb isotope compositions of the bottom waters only show small variations indicative of a consistent influence of Atlantic waters. Since the major intensification of the Northern Hemisphere Glaciation at 2.7 Ma the seawater Nd isotope composition has varied more pronouncedly due to changes in weathering inputs related to the waxing and waning of the ice sheets on Svalbard, the Barents Sea, and the Eurasian shelf, due to changes in water mass exchange and due to the increasing supply of ice-rafted debris (IRD) originating from the Arctic Ocean. The seawater Pb isotope record also exhibits a higher short-term variability after 2.7 Ma, but there is also a trend toward more radiogenic values, which reflects a combination of changes in input sources and enhanced incongruent weathering inputs of Pb released from freshly eroded old continental rocks.

Pond fractals in a tidal flat.

PubMed

Cael, B B; Lambert, Bennett; Bisson, Kelsey

2015-11-01

Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

Exploring Options for an Integrated Water Level Observation Network in Alaska

NASA Astrophysics Data System (ADS)

McCammon, M.

2016-02-01

Portions' of Alaska's remote coastlines are among the Nation's most vulnerable to geohazards such as tsunami, extra-tropical storm surge, and erosion; and the availability of observations of water levels, ocean waves, and river discharge are severely lacking to support water level warnings and forecasts. Alaska is experiencing dramatic reductions in sea ice cover, changes in extra-tropical storm surge patterns, and thawing permafrost. These conditions are endangering coastal populations throughout the State. Gaps in the ocean observing system limit our State's ability to provide useful marine and sea ice forecasts, especially in the Arctic. A spectrum of observation platforms may provide an optimal solution for filling the most critical gaps in these coastal and ocean areas. The collaborations described in this talk and better leveraging of resources and capabilities across federal, state, and academic partners will provide the best opportunity for advancing our science capacity and capabilities in this remote region.

Pond fractals in a tidal flat

NASA Astrophysics Data System (ADS)

Cael, B. B.; Lambert, Bennett; Bisson, Kelsey

2015-11-01

Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces.

Estimation of regional material yield from coastal landslides based on historical digital terrain modelling

USGS Publications Warehouse

Hapke, C.J.

2005-01-01

High-resolution historical (1942) and recent (1994) digital terrain models were derived from aerial photographs along the Big Sur coastline in central California to measure the long-term volume of material that enters the nearshore environment. During the 52-year measurement time period, an average of 21 000 ?? 3100 m3 km-1 a-1 of material was eroded from nine study sections distributed along the coast, with a low yield of 1000 ?? 240 m3 km-1 a-1 and a high of 46 700 ?? 7300 m3 km-1 a-1. The results compare well with known volumes from several deep-seated landslides in the area and suggest that the processes by which material is delivered to the coast are episodic in nature. In addition, a number of parameters are investigated to determine what influences the substantial variation in yield along the coast. It is found that the magnitude of regional coastal landslide sediment yield is primarily related to the physical strength of the slope-forming material. Coastal Highway 1 runs along the lower portion of the slope along this stretch of coastline, and winter storms frequently damage the highway. The California Department of Transportation is responsible for maintaining this scenic highway while minimizing the impacts to the coastal ecosystems that are part of the Monterey Bay National Marine Sanctuary. This study provides environmental managers with critical background data on the volumes of material that historically enter the nearshore from landslides, as well as demonstrating the application of deriving historical digital terrain data to model landscape evolution. Published in 2005 by John Wiley & Sons, Ltd.

Great differences in the critical erosion threshold between surface and subsurface sediments: A field investigation of an intertidal mudflat, Jiangsu, China

NASA Astrophysics Data System (ADS)

Shi, Benwei; Wang, Ya Ping; Wang, Li Hua; Li, Peng; Gao, Jianhua; Xing, Fei; Chen, Jing Dong

2018-06-01

Understanding of bottom sediment erodibility is necessary for the sustainable management and protection of coastlines, and is of great importance for numerical models of sediment dynamics and transport. To investigate the dependence of sediment erodibility on degree of consolidation, we measured turbidity, waves, tidal currents, intratidal bed-level changes, and sediment properties on an exposed macrotidal mudflat during a series of tidal cycles. We estimated the water content of surface sediments (in the uppermost 2 cm of sediment) and sub-surface sediments (at 2 cm below the sediment surface). Bed shear stress values due to currents (τc), waves (τw), and combined current-wave action (τcw) were calculated using a hydrodynamic model. In this study, we estimate the critical shear stress for erosion using two approaches and both of them give similar results. We found that the critical shear stress for erosion (τce) was 0.17-0.18 N/m2 in the uppermost 0-2 cm of sediment and 0.29 N/m2 in sub-surface sediment layers (depth, 2 cm), as determined by time series of τcw values and intratidal bed-level changes, and values of τce, obtained using the water content of bottom sediments, were 0.16 N/m2 in the uppermost 2 cm and 0.28 N/m2 in the sub-surface (depth, 2 cm) sediment. These results indicate that the value of τce for sub-surface sediments (depth, 2 cm) is much greater than that for the uppermost sediments (depth, 0-2 cm), and that the τce value is mainly related to the water content, which is determined by the extent of consolidation. Our results have implications for improving the predictive accuracy of models of sediment transport and morphological evolution, by introducing variable τce values for corresponding sediment layers, and can also provide a mechanistic understanding of bottom sediment erodibility at different sediment depths on intertidal mudflats, as related to differences in the consolidation time.

Low post-Cenomanian denudation depths across the Brazilian Northeast: Implications for long-term landscape evolution at a transform continental margin

NASA Astrophysics Data System (ADS)

Peulvast, Jean-Pierre; Claudino Sales, Vanda; Bétard, François; Gunnell, Yanni

2008-05-01

The Brazilian Northeast affords good opportunities for obtaining reliable timings and rates of landscape evolution based on stratigraphic correlations across a vast region. The landscape formed in the context of an episodically fluctuating but continuously falling base level since the Cenomanian. After formation of the transform passive margin in Aptian times, landscape development was further driven by a swell-like uplift with its crest situated ˜ 300 km from the coastline. The seaward flank of this swell or broad monocline between the interior Araripe and coastal Potiguar basins was eroded, and currently forms a deeply embayed plain bordered by a semi-circular, north-facing erosional escarpment. The post-Cenomanian uplift caused an inversion of the Cretaceous basins and generated a landscape in which the most elevated landforms correspond either to resistant Mesozoic sedimentary caprock, or to eroded stumps of syn-rift Cretaceous footwall uplands. Denudation in the last 90 My never exceeded mean rates of 10 m·My - 1 and exhumed a number of Cretaceous stratigraphic unconformities. As a result, some topographic surfaces at low elevations are effectively Mesozoic land surfaces that became re-exposed in Cenozoic times. The Neogene Barreiras Formation forms a continuous and mostly clastic apron near the coast. It testifies to the last peak of erosion in the hinterland and coincided with the onset of more arid climates at ˜ 13 Ma or earlier. The semi-circular escarpment is not directly related to the initial breakup rift flanks, which had been mostly eroded before the end of the Mesozoic, but the cause and exact timing of post-Cenomanian crustal upwarping are poorly constrained. It could perhaps have been a flexural response of the low-rigidity lithosphere to sediment loads on the margin, and thus a slowly ongoing process since the late Cretaceous. Uplift could instead be the consequence of a more discrete dynamic event related either to Oligocene magmatism in the region, or to continental-scale far-field stresses determined by Andean convergence.

Subtype Coastline Determination in Urban Coast Based on Multiscale Features: a Case Study in Tianjin, China

NASA Astrophysics Data System (ADS)

Song, Y.; Ai, Y.; Zhu, H.

2018-04-01

In urban coast, coastline is a direct factor to reflect human activities. It is of crucial importance to the understanding of urban growth, resource development and ecological environment. Due to complexity and uncertainty in this type of coast, it is difficult to detect accurate coastline position and determine the subtypes of the coastline. In this paper, we present a multiscale feature-based subtype coastline determination (MFBSCD) method to extract coastline and determine the subtypes. In this method, uncertainty-considering coastline detection (UCCD) method is proposed to separate water and land for more accurate coastline position. The MFBSCD method can well integrate scale-invariant features of coastline in geometry and spatial structure to determine coastline in subtype scale, and can make subtypes verify with each other during processing to ensure the accuracy of final results. It was applied to Landsat Thematic Mapper (TM) and Operational Land Imager (OLI) images of Tianjin, China, and the accuracy of the extracted coastlines was assessed with the manually delineated coastline. The mean ME (misclassification error) and mean LM (Line Matching) are 0.0012 and 24.54 m respectively. The method provides an inexpensive and automated means of coastline mapping with subtype scale in coastal city sectors with intense human interference, which can be significant for coast resource management and evaluation of urban development.

Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment

USGS Publications Warehouse

Benjamin W. Abbott,; Jeremy B. Jones,; Edward A.G. Schuur,; F.S. Chapin, III; Bowden, William B.; M. Syndonia Bret-Harte,; Howard E. Epstein,; Michael D. Flannigan,; Tamara K. Harms,; Teresa N. Hollingsworth,; Mack, Michelle C.; McGuire, A. David; Susan M. Natali,; Adrian V. Rocha,; Tank, Suzanne E.; Merrit R. Turetsky,; Jorien E. Vonk,; Wickland, Kimberly P.; Aiken, George R.

2016-01-01

As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%–85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

New view on tectonic structure of Siberian Sector of the Amerasian Basin (Arctic Ocean)

NASA Astrophysics Data System (ADS)

Vinokurov, Yu. I.

2014-05-01

In 2012, JSC Sevmorgeo with assistance of several research institutions of Federal Agency of Mineral Resources (Rosnedra) and Ministry of Defense carried out a unique set of offshore seismic and geological studies in the Mendeleev Rise area and adjacent areas of the Amerasia Basin. Two specially re-equipped icebreakers ("Kapitan Dranitsin" and "Dixon") were used in this campaign. The main results of the expedition were 5315 km of multichannel seismic profiles both with long and short streamers (4500 m and 600 m, respectively), 480 km long refraction profile crossing Mendeleev Rise. Seismic acquisition with short streamers was accompanied by deployment of sonobuoys. Geological studies included deep-water drilling and sea-bottom sampling by dredge, gravity corer, grab and by specially equipped research submarine. The newly acquired geological and geophysical data allowed for the following conclusions: 1. The Mendeleev Rise, the adjacent Lomonosov Ridge and Chukchi Plateau are the direct continuations of the East Siberian Sea tectonic structures. It is confirmed by direct tracking of some morphostructures, faults, gravity and magnetic anomalies from the shelf to deep-water highs. 2. The East Arctic Shelf and the adjacent Arctic Ocean represent offshore extent of the Verkhoyansk-Kolyma crustal domain constituted by a mosaic of separate blocks of the Pre-Cambrian basement (Okhotsk, Omulevka, Omolon, Wrangel-Gerald and Central Arctic) and Late Mesozoic orogens. This area differs significantly from the Ellesmerian crustal domain located to the east (including the Northwind Ridge, which coincides with inferred eastern boundary of the Mesozoides). The Central Arctic domain includes structures of the Mendeleev Ridge and the Chukchi Plateau. Western boundary of this block is inferred along the Spur of Geophysicists, which separates the Podvodnikov Basin into two unequal parts with different basement structure. From the south, southwest and west, the Central Arctic domain is surrounded by younger sedimentary basins: the Vilkitski Megatrough and Podvodnikov Basin, which may have been developing simultaneously. In the Cretaceous, the sediments were delivered mostly from deeply eroded areas of Central Arctic highs, including the Mendeleev Rise. In the beginning of Cenozoic, there was a dramatic reorganization in sediment supply to the Arctic Ocean with Siberian continental margin becoming the major provenance area leading to significant increase of the transported. The general pattern of the magnetic anomalies allows drawing a conclusion about similarity of the Mendeleev Rise and the neighboring De Long Uplift and Wrangel-Gerald Terrain, which constitute parts of HALIP magmatic province. The latter includes both offshore structures of the East Arctic and the structures of the Alpha-Mendeleev Rise. This conclusion is supported by results of sea-bottom geological sampling carried out as a part of our investigations. The crustal thickness and seismic velocity profile of the Mendeleev Rise and adjacent Lomonosov Ridge, Chukchi Plateau and Northwind Ridge are typical for the thinned continental crust. Thus, according to new data available today, the Central Arctic domain may be considered as a part of the deeply subsided Eurasian continental margin characterized by close relationship with the adjacent offshore and onshore structures.

New cetacean ΔR values for Arctic North America and their implications for marine-mammal-based palaeoenvironmental reconstructions

NASA Astrophysics Data System (ADS)

Furze, Mark F. A.; Pieńkowski, Anna J.; Coulthard, Roy D.

2014-05-01

Radiocarbon-dated marine mammal remains from emergent Arctic coastlines have frequently been used to reconstruct Holocene sea-ice histories. The use of such reconstructions has hitherto been complicated by uncertain marine reservoir corrections precluding meaningful intercomparisons with data reported in calibrated or sidereal years. Based on an exhaustive compilation of previously published marine mammal radiocarbon dates (both live-harvested materials and subfossils) from the Canadian Arctic Archipelago (CAA), new, statistically-derived δ13C and ΔR values are provided. Average δ13C values are: -16.1 ± 1.1‰ (bone collagen; n = 193) for bowhead (Balaena mysticetus); -14.4 ± 0.5‰ (n = 44; dentine) for beluga (Delphinapterus leucas); -14.8 ± 1.9‰ (teeth and tusks; n = 18) and -18.0 ± 4.7‰ (n = 9; bone collagen) for walrus (Odobenus rosmarus). ΔR values are 170 ± 95 14C years for bowhead (n = 23) and 240 ± 60 14C years for beluga (n = 12). Scarce data preclude calculation of meaningful, statistically robust walrus ΔR. Using the new ΔR values, an expanded and revised database of calibrated bowhead dates (651 dates; many used in previous CAA sea-ice reconstructions) shows pronounced late Quaternary spatio-temporal fluctuations in bone abundance. Though broadly resembling earlier bowhead subfossil frequency data, analysis of the new expanded database suggests early- and mid-Holocene increases in whale abundance to be of longer duration and lower amplitude than previously considered. A more even and persistent spread of infrequent low-abundance remains during “whale free” intervals is also seen. The dominance of three eastern regions (Prince Regent Inlet & Gulf of Boothia; Admiralty Inlet; Berlinguet Inlet/Bernier Bay) in the CAA data, collectively contributing up to 88% of all subfossil remains in the mid-Holocene, is notable. An analysis of calibrated regional sea-level index points suggests that severance of the Admiralty Inlet-Gulf of Boothia marine channel due to isostatically-driven regression may have played a significant role in enhanced whale mortality during this interval. Comparisons between the newly calibrated bowhead data and other regional sea-ice proxy data further highlight spatial and temporal discrepancies, potentially due to regional asynchronicities and variable sensitivities in proxy response to climate and oceanographic forcing. However, the limited number of deglacial-postglacial marine records continues to hamper extensive intercomparisons between marine mammal and other proxy datasets. Nevertheless, an examination of assumptions inherent in linking bowhead subfossil frequencies, population densities, and sea-ice thickness and distribution, shows that such relationships are highly complex. Factors such as broad sea-ice preferences, variable mortality rates and causes, long distance carcass transport, variable coastline and basin/channel geometries, and changing emergence rates all complicate the correlation of whale bone abundance to sea-ice histories.

A 15 year legacy of cloud and atmosphere observations in Barrow, Alaska

NASA Astrophysics Data System (ADS)

Shupe, M.

2012-12-01

For the past 15 years, the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program has operated the North Slope of Alaska (NSA) atmospheric observatory in Barrow, Alaska. Barrow offers many valuable perspectives on the Arctic environment that complement observations at lower latitudes. Unique features of the Arctic region include cold and dry atmospheric conditions, strong annual variability in sun light, a seasonally high-reflective surface, and persistent clouds that involve mixed-phase processes. ARM's ultimate objective with its flagship observatory at the northernmost point in U.S. territory is to provide measurements that can be used to improve the understanding of these atmospheric physical and radiative properties and processes such that they can be better represented in climate models. The NSA is the most detailed and long-lasting cloud-radiation-atmosphere observatory in the Arctic, providing continuous, sophisticated measurements of climate-relevant parameters. Instrument suites include active radars and lidars at various frequencies, passive radiometers monitoring radiation in microwave, infrared, visible and ultraviolet wavelengths, meteorological towers, and sounding systems. Together these measurements are used to characterize many of the important properties of clouds, aerosols, atmospheric radiation, dynamics, thermodynamics, and the surface. The coordinated nature of these measurements offers important multi-dimensional insight into many fundamental processes linking these different elements of the climate system. Moreover, the continuous operations of the facility support these observations over the full diurnal cycle and in all seasons of the year. This presentation will highlight a number of important studies and key findings that have been facilitated by the NSA observations during the first 15 years in operation. Some of these include: a thorough documentation of clouds, their occurrence frequency, phase, microphysical properties, and impacts on surface radiation; the indirect effect of aerosols on the surface longwave radiative effects of Arctic clouds; improved measurements of low amounts of atmospheric water vapor and their impacts on atmospheric radiation; dynamical and microphysical processes that are responsible for long-lived Arctic stratiform clouds; evaluation of satellite observations in extreme and observationally-difficult regimes; and assessment of model performance for models ranging from very high resolution to climate model simulations in the Arctic. The observational legacy at Barrow continues as ARM works to expand and enhance its impact. Plans are underway to install observational capabilities at a sister location in Oliktok Point to the east of Barrow, including enhanced capabilities of tethered balloon profiling and flying unmanned aerial vehicles over the adjacent Arctic Ocean. A new set of scanning cloud and precipitation radars have recently come online at Barrow that will allow for new insights on the spatial context of measurements at Barrow, including important information on the variability of atmospheric processes associated with the coastline. And lastly, there are many opportunities for the intensive observations at Barrow to inform important regional research on permafrost and sea-ice loss, while also serving as an unmatched, long-term record for evaluating atmospheric processes in regional and global climate models.

Autogenic and Allogenic: Emergent Coastline Patterns Interact With Forcing Variations

NASA Astrophysics Data System (ADS)

Murray, A. B.; Alvarez Antolinez, J. A.; Mendez, F. J.; Moore, L. J.; Wood, J.; Farley, G.

2017-12-01

A range of coastline shapes can emerge from large-scale morphodynamic interactions. Coastline shape determines local wave influences. Local wave influences (fluxes of alongshore momentum), determine sediment fluxes, and gradients in these sediment fluxes, in turn, alter coastline shape. Modeling studies show that such feedbacks lead to an instability, and to subsequent finite-amplitude interactions, producing self-organized patterns and emergent structures including sandwaves, capes, and spits (e.g. Ashton and Murray, 2006; Ashton et al., 2015); spiral bays on rocky coastlines (e.g. Barkwith et al., 2014); and convex, spit-bounded coastlines (Ells et al., in prep.). Coastline shapes depend sensitively on wave climate, defined as the angular distribution of wave influences on alongshore sediment transport. Therefore, shifts in wave climate arising from shifts in storms (decadal scale fluctuations or longer-term trends) will tend to change coastline shape. Previous efforts have detected changing coastline shape, likely related to changing influence from hurricane-generated waves, as expressed in changes in the location and intensity of coastal erosion zones along the cuspate capes in North Carolina, USA (Moore et al., 2013). These efforts involved the assumption that coastline response to changing forcing occurs in a quasi-equilibrium manner. However, in some cases coastline responses can exhibit long-term memory and path dependence (Thomas et al., 2016). Recently, we have hindcast the wave climate affecting the North Carolina coast since 1870, using a series of statistical analyses to downscale from basin-scale surface pressure fields to regional deep-water wave climate, and then a numerical transformation to local offshore wave climate. We used this wave climate as input for the Coastline Evolution Model (CEM). The results show that the emergent coastline features respond to decadal-scale shifts in wave climate, but with time lags that complicate the relationship between forcing and coastline shape. Comparisons between model predictions and observed shoreline-change patterns support the suggestion that the relationship between emergent coastline behaviours (autogenic processes) and external influences (autogenic forcing) involves such memory effects (Antolinez et al., in revision).

Assessing hazards along our Nation's coasts

USGS Publications Warehouse

Hapke, Cheryl J.; Brenner, Owen; Henderson, Rachel E.; Reynolds, B.J.

2013-01-01

Coastal areas are essential to the economic, cultural, and environmental health of the Nation, yet by nature coastal areas are constantly changing due to a variety of events and processes. Extreme storms can cause dramatic changes to our shorelines in a matter of hours, while sea-level rise can profoundly alter coastal environments over decades. These changes can have a devastating impact on coastal communities, such as the loss of homes built on retreating sea cliffs or protective dunes eroded by storm waves. Sometimes, however, the changes can be positive, such as new habitat created by storm deposits. The U.S. Geological Survey (USGS) is meeting the need for scientific understanding of how our coasts respond to different hazards with continued assessments of current and future changes along U.S. coastlines. Through the National Assessment of Coastal Change Hazards (NACCH), the USGS carries out the unique task of quantifying coastal change hazards along open-ocean coasts in the United States and its territories. Residents of coastal communities, emergency managers, and other stakeholders can use science-based data, tools, models, and other products to improve planning and enhance resilience.

Nearshore coastal mapping. [in Lake Michigan and Puerto Rico

NASA Technical Reports Server (NTRS)

Polcyn, F. C.; Lyzenga, D. R.

1975-01-01

Two test sites of different water quality and bottom topography were used to test for maximum water depth penetration using the Skylab S-192 MSS for measurement of nearshore coastal bathymetry. Sites under investigation lie along the Lake Michigan coastline where littoral transport acts to erode sand bluffs and endangers developments along 1,200 miles of shore, and on the west coast of Puerto Rico where unreliable shoal location and depth information constitutes a safety hazard to navigation. The S-192 and S-190A and B provide data on underwater features because of water transparency in the blue/green portion of the spectrum. Depth of 20 meters were measured with the S-192 in the Puerto Rico test site. The S-190B photography with its improved spatial resolution clearly delineates the triple sand bar topography in the Lake Michigan test site. Several processing techniques were employed to test for maximum depth measurement with least error. The results are useful for helping to determine an optimum spectral bandwidth for future space sensors that will increase depth measurements for different water attenuation conditions where a bottom reflection is detectable.

Principal sources and dispersal patterns of suspended particulate matter in nearshore surface waters of the northeast Pacific Ocean and the Hawaiian Islands

NASA Technical Reports Server (NTRS)

Carlson, P. R. (Principal Investigator); Conomos, T. J.; Janda, R. J.; Peterson, D. H.

1973-01-01

The author has identified the following significant results. ERTS-1 multispectral scanner imagery of the nearshore surface waters of the Northeast Pacific Ocean is proving to be a useful tool for determining source and dispersal of suspended particulate matter. The principal sources of the turbid water, seen best on the green and red bands, are river and stream effluents and actively eroding coastlines; secondary sources are waste effluents and production of planktonic organisms, but these may sometimes be masked by the very turbid plumes of suspended sediment being discharged into the nearshore zone during times of high river discharge. The configuration and distribution of the plumes of turbid water also can be used to infer near-surface current directions. Comparison of imagery of the nearshore water off the northern California coast from October 1972 and January 1973 shows a reversal of the near-surface currents, from predominantly south-setting in the fall (California Current) to north-setting in the winter (Davidson Current).

Review of Nearshore Morphologic Prediction

NASA Astrophysics Data System (ADS)

Plant, N. G.; Dalyander, S.; Long, J.

2014-12-01

The evolution of the world's erodible coastlines will determine the balance between the benefits and costs associated with human and ecological utilization of shores, beaches, dunes, barrier islands, wetlands, and estuaries. So, we would like to predict coastal evolution to guide management and planning of human and ecological response to coastal changes. After decades of research investment in data collection, theoretical and statistical analysis, and model development we have a number of empirical, statistical, and deterministic models that can predict the evolution of the shoreline, beaches, dunes, and wetlands over time scales of hours to decades, and even predict the evolution of geologic strata over the course of millennia. Comparisons of predictions to data have demonstrated that these models can have meaningful predictive skill. But these comparisons also highlight the deficiencies in fundamental understanding, formulations, or data that are responsible for prediction errors and uncertainty. Here, we review a subset of predictive models of the nearshore to illustrate tradeoffs in complexity, predictive skill, and sensitivity to input data and parameterization errors. We identify where future improvement in prediction skill will result from improved theoretical understanding, and data collection, and model-data assimilation.

Accelerated relative sea-level rise and rapid coastal erosion: Testing a causal relationship for the Louisiana barrier islands

USGS Publications Warehouse

List, J.H.; Sallenger, A.H.; Hansen, M.E.; Jaffe, B.E.

1997-01-01

The role of relative sea-level rise as a cause for the rapid erosion of Louisiana's barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s. 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium Criterion this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus in terms of the Bruun approach relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

Oblique Aerial Photography of the Arctic Coast of Alaska, Cape Sabine to Milne Point, July 16-19, 2009

USGS Publications Warehouse

Gibbs, Ann E.; Richmond, Bruce M.

2010-01-01

The Arctic Coastal Plain of northern Alaska, an area of strategic economic importance to the United States, is home to remote Native American communities and encompasses unique habitats of global significance. Coastal erosion along the Arctic coast is chronic and widespread; recent evidence suggests that erosion rates are among the highest in the world (as high as ~16 m/yr) and may be accelerating. Coastal erosion adversely impacts energy-related infrastructure, natural shoreline habitats, and Native American communities. Climate change is thought to be a key component of recent environmental changes in the Arctic. Reduced sea-ice cover in the Arctic Ocean is one of the probable mechanisms responsible for increasing coastal exposure to wave attack and the resulting increase in erosion. Extended periods of permafrost melting and associated decreases in bluff cohesion and stability are another possible source of the increase in erosion. Several studies of selected areas on the Alaska coast document past shoreline positions and coastal change, but none have examined the entire North coast systematically. Results from these studies indicate high rates of coastal retreat that vary spatially along the coast. To address the need for a comprehensive and regionally consistent evaluation of shoreline change along the North coast of Alaska, the U.S. Geological Survey (USGS), as part of their Coastal and Marine Geology Program's (CMGP) National Assessment of Shoreline Change Study, is evaluating shoreline change from Peard Bay to the United States/Canadian border, using historical maps and photography and a standardized methodology that is consistent with other shoreline-change studies along the Nation's coastlines (see, for example, http://coastal.er.usgs.gov/shoreline-change/, last accessed February 12, 2010). This is the second in a series of publications containing photographs collected during reconnaissance surveys conducted in support of the National Assessment of Shoreline Change Study. An accompanying ESRI ArcGIS shape file (and plaintext copy) indicates the position of the aircraft and time when each photograph was taken. The USGS-CMGP Field Activity ID for the survey is A-5-09-AK, and more information on the survey and how to view the photographs using Google Earth software is available online at http://walrus.wr.usgs.gov/infobank/a/a509ak/html/a-5-09-ak.photos.kmz (last accessed February 12, 2010). The initial report ?Oblique aerial photography of the Arctic coast of Alaska, Nulavik to Demarcation Point, August 7-10, 2006? is available online at http://pubs.usgs.gov/ds/436/, and the associated Google Earth .kmz file is available at http://walrus.wr.usgs.gov/infobank/a/a106ak/html/a-1-06-ak.photos.kmz (last accessed February 12, 2010).

Collaborative community hazard exposure mapping: Distant Early Warning radar sites in Alaska's North Slope

NASA Astrophysics Data System (ADS)

Brady, M.

2015-12-01

A method to produce hazard exposure maps that are developed in collaboration with local coastal communities is the focus of this research. Typically efforts to map community exposure to climate threats over large areas have limited consideration of local perspectives about associated risks, constraining their utility for local management. This problem is especially acute in remote locations such as the Arctic where there are unique vulnerabilities to coastal threats that can be fully understood only through inclusion of community stakeholders. Through collaboration with community members, this study identifies important coastal assets and places and surveys local perspectives of exposure to climate threats along Alaska's vast North Slope coastline spanning multiple municipalities. To model physical exposure, the study adapts the U.S. Geological Survey's (USGS) coastal vulnerability index (CVI) to the Arctic context by incorporating the effects of open water distance determined by sea ice extent, and assigning CVI values to coastal assets and places according to direction and proximity. The study found that in addition to concerns about exposed municipal and industrial assets, North Slope communities viewed exposure of traditional activity sites as presenting a particular risk for communities. Highly exposed legacy Cold War Distant Early Warning Line sites are of particular concern with impacts ranging from financial risk to contamination of sensitive coastal marine environments. This research demonstrates a method to collaboratively map community exposure to coastal climate threats to better understand local risks and produce locally usable exposure maps.

Analysis of Decadal-Scale Shoreline Change along the Hamlet of Paulatuk (Canadian Arctic), using Landsat Satellite Imagery and GIS techniques from 1984 to 2014.

NASA Astrophysics Data System (ADS)

Sankar, R. D.; Murray, M. S.; Wells, P.

2016-12-01

Increased accuracy in estimating coastal change along localized segments of the Canadian Arctic coast is essential, in order to identify plausible adaptation initiatives to deal with the effects of climate change. This paper quantifies rates of shoreline movement along an 11 km segment of the Hamlet of Paulatuk (Northwest Territories, Canada), using an innovative modelling technique - Analyzing Moving Boundaries Using R (AMBUR). Approximately two dozen shorelines, obtained from high-resolution Landsat satellite imagery were analyzed. Shorelines were extracted using the band ratio method and compiled in ArcMapTM to determine decadal trends of coastal change. The unique geometry of Paulatuk facilitated an independent analysis of the western and eastern sections of the study area. Long-term (1984-2014) and short-term (1984-2003) erosion and accretion rates were calculated using the Linear Regression and End Point Rate methods respectively. Results reveal an elevated rate of erosion for the western section of the hamlet over the long-term (-1.1 m/yr), compared to the eastern portion (-0.92 m/yr). The study indicates a significant alongshore increase in the rates of erosion on both portions of the study area, over the short-term period 1984 to 2003. Mean annual erosion rates increased over the short-term along the western segment (-1.4 m/yr), while the eastern shoreline retreated at a rate of -1.3 m/yr over the same period. The analysis indicates that an amalgamation of factors may be responsible for the patterns of land loss experienced along Paulatuk. These include increased sea-surface temperature coupled with dwindling arctic ice and elevated storm hydrodynamics. The analysis further reveals that the coastline along the eastern portion of the hamlet, where the majority of the population reside, is vulnerable to a high rate of shoreline erosion.

Earth observation taken by the Expedition 33 crew.

NASA Image and Video Library

2012-11-17

ISS033-E-022378 (17 Nov. 2012) --- The Appalachian Mountains in the eastern Unites States are featured in this image photographed by an Expedition 33 crew member on the International Space Station. This regional view shows the striking visual effect of the valley-and-ridge topography of the Appalachian Mountains as viewed from orbit. The view shows more than 300 miles (500 kilometers) of this low mountain chain, from northeast Pennsylvania (lower left) to southern West Virginia, where a dusting of snow can be seen (top center). Sunglint reflections reveal detail of Chesapeake Bay and the great bend of the Potomac River. Cities are difficult to detect from space during daylight hours, so the sickle-shaped bend of the river is a good visual guide for station crew members trying to photograph the nation?s capital, Washington D.C. (upper left). The farm-dominated Piedmont Plateau is the light-toned area between the mountains and the bay. The Appalachian Mountains appear striped because the ridges are forested; providing a dense and dark canopy cover, while the valleys are farmed with crops that generally appear as lighter-toned areas. Geologically the valleys are the softer, more erodible rock layers, much the preferred places for human settlement. Not only do the larger rivers occupy the valley floors, but all the larger rivers flow in them, soils are thicker, slopes are gentle, and valleys are better protected from winter winds. According to scientists, rocks that form the valley-and-ridge province, as it is known, are relatively old (540-300 million years old), and were laid down in horizontal layers when North America was attached to Europe as the ancient supercontinent of Laurasia. During this time Gondwanaland ? an ancient supercontinent that included present-day Africa, India, South America, Australia and Antarctica - was approaching Laurasia under the influence of plate tectonics. The northwest coastline of modern Africa was the section of Gondwanaland that ?bumped up? against modern North America over a long period (320 ? 260 million years ago), according to scientists. The net result of the tectonic collision was the building of a major mountain chain, much higher than the present Appalachian range?in the process of which the flat-lying rock layers were crumpled up into a series of tight folds, at right angles to the advance of Gondwanaland. The collision also formed the singular supercontinent of Pangaea. The scientists say that, over the following 200 million years, Pangaea broke apart; the modern Atlantic Ocean formed; and erosion wore down the high mountains. What is left to see are the coastline of North America, and the eroded stumps of the mountain chain as the relatively low, but visually striking present-day Appalachian Mountains.

National Assessment of Historical Shoreline Change: A Pilot Study of Historical Coastal Bluff Retreat in the Great Lakes, Erie, Pennsylvania

USGS Publications Warehouse

Hapke, Cheryl J.; Malone, Shamus; Kratzmann, Meredith G.

2009-01-01

Coastal bluff retreat is a chronic problem along many high-relief coastlines in the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regard-ing trends and rates of bluff retreat. There is also a need for a comprehensive analysis that is consistent from one coastal region to another. To address these national needs, the U.S. Geological Survey (USGS), as part of the National Assessment of Coastal Change Hazards Project, conducted a pilot study of bluff retreat along the Lake Erie, Pa., coastline to assess the feasibility of undertaking a larger, multi-state analysis in the Great Lakes region. This report provides an overview of the pilot-study location and bluff geomorphology, the data sources and methodology, results of the analysis, and a discussion of the feasibility of undertaking a similar analysis along eroding bluffs in other Great Lakes states. This pilot study is part of an ongoing effort by the USGS to provide a comprehensive analysis of historical shoreline change and cliff and bluff retreat along open-ocean coastlines of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of the work is to develop standard, repeatable methods for mapping and analyzing coastal change so that systematic and consistent periodic updates of coastal erosion can be made nationally. Bluff-retreat evaluations are conducted by comparing the location of a historical bluff edge digitized from aerial photographs with those of recent bluff edges interpreted from both aerial photographs and lidar topographic surveys. The historical bluff edge is from 1938, whereas the more recent bluff edges are from 1998 and 2006 lidar data. Long-term (68-year) rates of retreat are calculated using the available bluff-edge data. The rates of retreat presented in this report represent conditions from the 1930s to 1998/2006, and are not intended for predicting future bluff-edge positions or rates of retreat. The report presents bluff-retreat rates for 32 km of a 60-km stretch along the Lake Erie, Pa., coastline. Data are discontinuous due to gaps in source data and lack of continuous bluffs. The average rate of coastal bluff retreat for the Lake Erie, Pa., bluffs was -0.3 +- 0.1 m/yr (retreat rates are presented as negative numbers in this report), based on rates averaged from 1,595 individual transects. Retreat rates generally were lowest where bedrock outcrops are exposed as the basal unit in the bluff. The highest rates are associated with anthropogenic activities, including jetties that trap littoral sediment, depleting a source of material for the natural replenishment of protective beaches downcoast, and extensive irrigation of farmlands on the tops of the bluffs, which can destabilize bluffs by enhancing ground-water outflow.

Marine debris in five national parks in Alaska.

PubMed

Polasek, L; Bering, J; Kim, H; Neitlich, P; Pister, B; Terwilliger, M; Nicolato, K; Turner, C; Jones, T

2017-04-15

Marine debris is a management issue with ecological and recreational impacts for agencies, especially on remote beaches not accessible by road. This project was implemented to remove and document marine debris from five coastal National Park Service units in Alaska. Approximately 80km of coastline were cleaned with over 10,000kg of debris collected. Marine debris was found at all 28 beaches surveyed. Hard plastics were found on every beach and foam was found at every beach except one. Rope/netting was the next most commonly found category, present at 23 beaches. Overall, plastic contributed to 60% of the total weight of debris. Rope/netting (14.6%) was a greater proportion of the weight from all beaches than foam (13.3%). Non-ferrous metal contributed the smallest amount of debris by weight (1.7%). The work forms a reference condition dataset of debris surveyed in the Western Arctic and the Gulf of Alaska within one season. Copyright © 2017. Published by Elsevier Ltd.

Rapid Arctic Transitions in Relation to Infrastructure and Climate Change: Comparison of the Permafrost and Geoecological Conditions in the Bovanenkovo Gas Field, Russia and the Prudhoe Bay Oil Field, Alaska

NASA Astrophysics Data System (ADS)

Walker, D. A.; Raynolds, M. K.; Kumpula, T.; Shur, Y.; Kanevskiy, M. Z.; Kofinas, G.; Leibman, M. O.; Matyshak, G. V.; Epstein, H. E.; Buchhorn, M.; Wirth, L.; Forbes, B. C.

2014-12-01

Many areas of the Arctic are undergoing rapid permafrost and ecosystem transitions resulting from a combination of industrial development and climate change as summer sea ice retreats and abundant Arctic natural resources become more accessible for extraction. The Bovanenkovo Gas Field (BGF) in Russia and the Prudhoe Bay Oilfield (PBO) in Alaska are among the oldest and most extensive industrial complexes in the Arctic, situated in areas with extensive ice-rich permafrost. Ongoing studies of cumulative effects in both regions are part of the Northern Eurasia Earth-Science Partnership Initiative (NEESPI) and NASA's Land-Cover Land-Use Change (LCLUC) research. Comparative analysis is focused on changes occurring due to different climate, permafrost, land-use, and disturbance regimes in the BGF and PBO and along bioclimate transects that contain both fields. Documentation of the changes in relationship to the different geoecological and social-economic conditions will help inform management approaches to minimize the effects of future activities. We compare the area of disturbance in the two fields and some of the key differences in the permafrost conditions. Detailed remote sensing and geoecological mapping in both areas reveal major differences in permafrost conditions that have implications for total ecological function. At BGF, highly erodible sands and the presence of massive tabular ground ice near the surface contributes to landslides and thermo-denudation of slopes. At PBO, ice-wedge degradation is the most noticeable change, where thermokarst is expanding rapidly along ice-wedges adjacent to roads and in areas away from roads. Between 1990 and 2001, coincident with strong atmospheric warming during the 1990s, natural thermokarst resulted in conversion of low-centered ice-wedge polygons to high-centered polygons, more active lakeshore erosion and increased landscape and habitat heterogeneity. These geoecololgical changes have local and regional consequences to wildlife habitat, land-use, and infrastructure. A conceptual model describes how infrastructure-related factors, including road dust and roadside flooding, are contributing to more extensive thermokarst in areas adjacent to roads and gravel pads in the PBO.

Uncovering biological soil crusts: carbon content and structure of intact Arctic, Antarctic and alpine biological soil crusts

NASA Astrophysics Data System (ADS)

Jung, Patrick; Briegel-Williams, Laura; Simon, Anika; Thyssen, Anne; Büdel, Burkhard

2018-02-01

Arctic, Antarctic and alpine biological soil crusts (BSCs) are formed by adhesion of soil particles to exopolysaccharides (EPSs) excreted by cyanobacterial and green algal communities, the pioneers and main primary producers in these habitats. These BSCs provide and influence many ecosystem services such as soil erodibility, soil formation and nitrogen (N) and carbon (C) cycles. In cold environments degradation rates are low and BSCs continuously increase soil organic C; therefore, these soils are considered to be CO2 sinks. This work provides a novel, non-destructive and highly comparable method to investigate intact BSCs with a focus on cyanobacteria and green algae and their contribution to soil organic C. A new terminology arose, based on confocal laser scanning microscopy (CLSM) 2-D biomaps, dividing BSCs into a photosynthetic active layer (PAL) made of active photoautotrophic organisms and a photosynthetic inactive layer (PIL) harbouring remnants of cyanobacteria and green algae glued together by their remaining EPSs. By the application of CLSM image analysis (CLSM-IA) to 3-D biomaps, C coming from photosynthetic active organisms could be visualized as depth profiles with C peaks at 0.5 to 2 mm depth. Additionally, the CO2 sink character of these cold soil habitats dominated by BSCs could be highlighted, demonstrating that the first cubic centimetre of soil consists of between 7 and 17 % total organic carbon, identified by loss on ignition.

Predicting Occurrences of Retrogressive Thaw Slumps and their Implications on the Near Shore Carbon Budget Along the Yukon Coast, Canada

NASA Astrophysics Data System (ADS)

Ramage, J. L.; Konopczak, A. M.; Morgenstern, A.; Lantuit, H.

2016-12-01

Permafrost degradation processes such as thermokarst and thermo-erosion create highly dynamic landforms that reshape Arctic landscapes. Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic. RTSs lead to the displacement of large volumes of sediments and are a major source of instability for biomass, hydrology and carbon storage in permafrost terrains. Studies have shown that in various Arctic areas, the number of RTSs has increased tremendously over the past decades. The processes initiating RTSs are well defined; however, little research has been done on regional scale to reveal the major terrain controls on their development. There is a clear need to shed light on the heterogeneous distribution of RTSs in the Arctic. Our research provides new insights into the dynamics of coastal RTSs. It highlights the main geomorphic factors causing RTSs along a 235 km coastal segment of the Yukon Coastal Plain, Canada. We 1) explain differences in the density of RTSs, 2) ascertain the factors controlling their size, and 3) draw an RTSs occurrence susceptibility map, based on the evolution of RTSs in the area over 59 years (1952-2011). We used a large set of high-resolution multispectral satellite images produced in 2011 for geocoding aerial photographs from the 1950s and the 1970s. Using remote sensing, we compared the numbers of RTSs and surface area covered by them in the 1950s, 1970s and in 2011. We highlighted the main terrain controls over the development of RTSs using multivariate and boosted regression trees. Based on the 2011 satellite imagery, we detected 286 coastal RTSs in the study area. Higher densities of RTSs were found in terrains with moderate slopes and high pore ice volumes. RTSs were larger in terrains containing high volumes of massive ice. The number of RTSs has increased by 41.2% during the study period (1952 - 2011), mainly due to important RTSs development on moraine deposits. We did not observe an increase in the size of RTSs throughout the study period. This study shows that the variability of short-term coastline dynamics in the area is highly amplified by permafrost degradation processes acting on ice-rich coasts. As a result, we expect that the reported amounts of sediments released into the Beaufort Sea are related to RTSs development.

The Effect of Coastline Changes to Local Community's Social-Economic

NASA Astrophysics Data System (ADS)

Hassan, M. I.; Rahmat, N. H.

2016-09-01

The coastal area is absolutely essential for the purposes of resident, recreation, tourism, fisheries and agriculture as a source of socio-economic development of local community. Some of the activities will affect the coastline changes. Coastline changes may occur due to two main factors include natural factors and also by the factor of human activities in coastal areas. Sea level rise, erosion and sedimentation are among the factors that can contribute to the changes in the coastline naturally, while the reclamation and development in coastal areas are factors of coastline changes due to human activities. Resident area and all activities in coastal areas will provide economic resources to the residents of coastal areas. However, coastline changes occur in the coastal areas will affect socio-economic for local community. A significant effect can be seen through destruction of infrastructure, loss of land, and destroy of crops. Batu Pahat is an area with significant changes of coastline. The changes of coastline from 1985 to 2013 can be determined by using topographical maps in 1985 and satellite images where the changes images are taken in 2011 and 2013 respectively. To identify the changes of risk areas, Coastal Vulnerability Index (CVI) is used to indicate vulnerability for coastal areas. This change indirectly affects the source of income in their agricultural cash crops such as oil palm and coconut. Their crops destroyed and reduced due to impact of changes in the coastline. Identification of risk coastal areas needs to be done in order for the society and local authorities to be prepared for coastline changes.

Safe Shores and Resilient Transit Corridors: Using Science, Design, and Stakeholder Partnerships to Address Connecticut's Coastal Vulnerabilities

NASA Astrophysics Data System (ADS)

French, R. A.; Felson, A. J.; Kirmmse, E.; Hagemann, K.

2015-12-01

Connecticut's densely developed coastline is highly vulnerable to sea level rise and coastal storms. 95% of the state's entire population lives within 50 miles of the shore. Connecticut has more than $542 billion in insured assets in harms way, only Florida has a greater exposure. As part of the state of Connecticut Phase 1 application for the HUD National Disaster Resilience Competition, the Connecticut Institute for Resilience and Climate Adaptation (CIRCA) at the University of Connecticut undertook an assessment of coastal vulnerabilities, including the impacts of sea level rise on the frequency of flooding, socioeconomic factors, critical infrastructure, and housing using data collected from federal, state, and municipal sources. Connecticut's unique geology, characterized by a glaciated coastline with highly erodible former deltas and elevated ridgelines extending out to rocky headlands, became the basis of the climate adaptation approach. Together with a nine state agency workgroup, municipal and regional government, and non-profit and industry representatives, CIRCA and the Yale UED lab developed a long-term urban redevelopment solution of resilient access and egress corridors layered over ridgelines and resilient zones of transit oriented economic development linked to shoreline communities. This concept can be applied in both Connecticut's coastal cities like New Haven and its smaller towns. The process demonstrated the effective partnership between the universities and state agencies in bringing the science of flood modeling and mapping together with innovative design to create solutions for climate adaptation. However, it also revealed significant gaps in data availability to analyze the economic and social drivers for adopting different adaptation strategies. Furthermore, the accuracy of current flood mapping tools needs to be improved to predict future flooding at the municipal project scale. As Connecticut and other states move forward with resilience planning, continued investment in physical and social sciences at the local level will be necessary to effectively implement those plans.

Automated Feature Extraction of Foredune Morphology from Terrestrial Lidar Data

NASA Astrophysics Data System (ADS)

Spore, N.; Brodie, K. L.; Swann, C.

2014-12-01

Foredune morphology is often described in storm impact prediction models using the elevation of the dune crest and dune toe and compared with maximum runup elevations to categorize the storm impact and predicted responses. However, these parameters do not account for other foredune features that may make them more or less erodible, such as alongshore variations in morphology, vegetation coverage, or compaction. The goal of this work is to identify other descriptive features that can be extracted from terrestrial lidar data that may affect the rate of dune erosion under wave attack. Daily, mobile-terrestrial lidar surveys were conducted during a 6-day nor'easter (Hs = 4 m in 6 m water depth) along 20km of coastline near Duck, North Carolina which encompassed a variety of foredune forms in close proximity to each other. This abstract will focus on the tools developed for the automated extraction of the morphological features from terrestrial lidar data, while the response of the dune will be presented by Brodie and Spore as an accompanying abstract. Raw point cloud data can be dense and is often under-utilized due to time and personnel constraints required for analysis, since many algorithms are not fully automated. In our approach, the point cloud is first projected into a local coordinate system aligned with the coastline, and then bare earth points are interpolated onto a rectilinear 0.5 m grid creating a high resolution digital elevation model. The surface is analyzed by identifying features along each cross-shore transect. Surface curvature is used to identify the position of the dune toe, and then beach and berm morphology is extracted shoreward of the dune toe, and foredune morphology is extracted landward of the dune toe. Changes in, and magnitudes of, cross-shore slope, curvature, and surface roughness are used to describe the foredune face and each cross-shore transect is then classified using its pre-storm morphology for storm-response analysis.

International migration patterns of Red-throated Loons (Gavia stellata) from four breeding populations in Alaska

USGS Publications Warehouse

McCloskey, Sarah E.; Uher-Koch, Brian D.; Schmutz, Joel A.; Fondell, Thomas F.

2018-01-01

Identifying post-breeding migration and wintering distributions of migratory birds is important for understanding factors that may drive population dynamics. Red-throated Loons (Gavia stellata) are widely distributed across Alaska and currently have varying population trends, including some populations with recent periods of decline. To investigate population differentiation and the location of migration pathways and wintering areas, which may inform population trend patterns, we used satellite transmitters (n = 32) to describe migration patterns of four geographically separate breeding populations of Red-throated Loons in Alaska. On average (± SD) Red-throated Loons underwent long (6,288 ± 1,825 km) fall and spring migrations predominantly along coastlines. The most northern population (Arctic Coastal Plain) migrated westward to East Asia and traveled approximately 2,000 km farther to wintering sites than the three more southerly populations (Seward Peninsula, Yukon-Kuskokwim Delta, and Copper River Delta) which migrated south along the Pacific coast of North America. These migration paths are consistent with the hypothesis that Red-throated Loons from the Arctic Coastal Plain are exposed to contaminants in East Asia. The three more southerly breeding populations demonstrated a chain migration pattern in which the more northerly breeding populations generally wintered in more northerly latitudes. Collectively, the migration paths observed in this study demonstrate that some geographically distinct breeding populations overlap in wintering distribution while others use highly different wintering areas. Red-throated Loon population trends in Alaska may therefore be driven by a wide range of effects throughout the annual cycle.

Using the Alaska Ocean Observing System to Inform Decision Making for Coastal Resiliency Relating to Inundation, Ocean Acidification, Harmful Algal Blooms, Navigation Safety and Impacts of Vessel Traffic

NASA Astrophysics Data System (ADS)

McCammon, M.

2017-12-01

State and federal agencies, coastal communities and Alaska Native residents, and non-governmental organizations are increasingly turning to the Alaska Ocean Observing System (AOOS) as a major source of ocean and coastal data and information products to inform decision making relating to a changing Arctic. AOOS implements its mission to provide ocean observing data and information to meet stakeholder needs by ensuring that all programs are "science based, stakeholder driven and policy neutral." Priority goals are to increase access to existing coastal and ocean data; package information and data in useful ways to meet stakeholder needs; and increase observing and forecasting capacity in all regions of the state. Recently certified by NOAA, the AOOS Data Assembly Center houses the largest collection of real-time ocean and coastal data, environmental models, and biological data in Alaska, and develops tools and applications to make it more publicly accessible and useful. Given the paucity of observations in the Alaska Arctic, the challenge is how to make decisions with little data compared to other areas of the U.S. coastline. AOOS addresses this issue by: integrating and visualizing existing data; developing data and information products and tools to make data more useful; serving as a convener role in areas such as coastal inundation and flooding, impacts of warming temperatures on food security, ocean acidification, observing technologies and capacity; and facilitating planning efforts to increase observations. In this presentation, I will give examples of each of these efforts, lessons learned, and suggestions for future actions.

Expanding Alaska's Remote Ocean Observing Capabilities Using Robotic Gliders and Remote Sensing Technologies

NASA Astrophysics Data System (ADS)

Janzen, C.; McCammon, M.; Winsor, P.; Murphy, D. J.; Mathis, J. T.; Baumgartner, M.; Stafford, K.; Statscewich, H.; Evans, W.; Potter, R. A.

2016-02-01

The Alaska Ocean Observing System (AOOS) is directed by Congress to facilitate, implement and support ocean observing for the entire coast of Alaska, working with federal, state, local and private sector partners. However, developing an integrated ocean observing system at high latitudes presents unique challenges. In addition to the harsh environment, the region covered by AOOS is made up of nearly 44,000 miles of coastline, larger than the marine systems in the rest of the United States combined. No other observing system in the United States has such climate extremes, significant geographic distances, and limited observing infrastructure. Making use of robotic technologies in Alaskan waters has been successfully demonstrated with the pilot deployment of a real-time marine mammal detection system deployed on a Slocum buoyancy controlled glider. The glider also carries payload to measure high resolution temperature and salinity data. With these simultaneous data streams, scientists are investigating how marine mammal occurrences are related to water column conditions and mixing fronts, as well as comparing northern versus southern Chukchi community composition, inshore (Alaska Coastal Current) waters, and offshore (Bering Sea) waters. In its third year, the glider is now equipped with lithium batteries that allow it to operate unattended for an entire Arctic summer season, whereas past deployments were limited to about 10 days. Developing and applying such cutting edge, long-endurance autonomous technology is benefitting others monitoring in Arctic regions where shipboard access is not only expensive, but limited to fair weather conditions during the openwater (ice free) seasons of summer to early fall.

a Fast Segmentation Algorithm for C-V Model Based on Exponential Image Sequence Generation

NASA Astrophysics Data System (ADS)

Hu, J.; Lu, L.; Xu, J.; Zhang, J.

2017-09-01

For the island coastline segmentation, a fast segmentation algorithm for C-V model method based on exponential image sequence generation is proposed in this paper. The exponential multi-scale C-V model with level set inheritance and boundary inheritance is developed. The main research contributions are as follows: 1) the problems of the "holes" and "gaps" are solved when extraction coastline through the small scale shrinkage, low-pass filtering and area sorting of region. 2) the initial value of SDF (Signal Distance Function) and the level set are given by Otsu segmentation based on the difference of reflection SAR on land and sea, which are finely close to the coastline. 3) the computational complexity of continuous transition are successfully reduced between the different scales by the SDF and of level set inheritance. Experiment results show that the method accelerates the acquisition of initial level set formation, shortens the time of the extraction of coastline, at the same time, removes the non-coastline body part and improves the identification precision of the main body coastline, which automates the process of coastline segmentation.

Automatic sub-pixel coastline extraction based on spectral mixture analysis using EO-1 Hyperion data

NASA Astrophysics Data System (ADS)

Hong, Zhonghua; Li, Xuesu; Han, Yanling; Zhang, Yun; Wang, Jing; Zhou, Ruyan; Hu, Kening

2018-06-01

Many megacities (such as Shanghai) are located in coastal areas, therefore, coastline monitoring is critical for urban security and urban development sustainability. A shoreline is defined as the intersection between coastal land and a water surface and features seawater edge movements as tides rise and fall. Remote sensing techniques have increasingly been used for coastline extraction; however, traditional hard classification methods are performed only at the pixel-level and extracting subpixel accuracy using soft classification methods is both challenging and time consuming due to the complex features in coastal regions. This paper presents an automatic sub-pixel coastline extraction method (ASPCE) from high-spectral satellite imaging that performs coastline extraction based on spectral mixture analysis and, thus, achieves higher accuracy. The ASPCE method consists of three main components: 1) A Water- Vegetation-Impervious-Soil (W-V-I-S) model is first presented to detect mixed W-V-I-S pixels and determine the endmember spectra in coastal regions; 2) The linear spectral mixture unmixing technique based on Fully Constrained Least Squares (FCLS) is applied to the mixed W-V-I-S pixels to estimate seawater abundance; and 3) The spatial attraction model is used to extract the coastline. We tested this new method using EO-1 images from three coastal regions in China: the South China Sea, the East China Sea, and the Bohai Sea. The results showed that the method is accurate and robust. Root mean square error (RMSE) was utilized to evaluate the accuracy by calculating the distance differences between the extracted coastline and the digitized coastline. The classifier's performance was compared with that of the Multiple Endmember Spectral Mixture Analysis (MESMA), Mixture Tuned Matched Filtering (MTMF), Sequential Maximum Angle Convex Cone (SMACC), Constrained Energy Minimization (CEM), and one classical Normalized Difference Water Index (NDWI). The results from the three test sites indicated that the proposed ASPCE method extracted coastlines more efficiently than did the compared methods, and its coastline extraction accuracy corresponded closely to the digitized coastline, with 0.39 pixels, 0.40 pixels, and 0.35 pixels in the three test regions, showing that the ASPCE method achieves an accuracy below 12.0 m (0.40 pixels). Moreover, in the quantitative accuracy assessment for the three test sites, the ASPCE method shows the best performance in coastline extraction, achieving a 0.35 pixel-level at the Bohai Sea, China test site. Therefore, the proposed ASPCE method can extract coastline more accurately than can the hard classification methods or other spectral unmixing methods.

Optimizing romanian maritime coastline using mathematical model Litpack

NASA Astrophysics Data System (ADS)

Anton, I. A.; Panaitescu, M.; Panaitescu, F. V.

2017-08-01

There are many methods and tools to study shoreline change in coastal engineering. LITPACK is a numerical model included in MIKE software developed by DHI (Danish Hydraulic Institute). With this matehematical model we can simulate coastline evolution and profile along beach. Research and methodology: the paper contents location of the study area, the current status of Midia-Mangalia shoreline, protection objectives, the changes of shoreline after having protected constructions. In this paper are presented numerical and graphycal results obtained with this model for studying the romanian maritime coastline in area MIDIA-MANGALIA: non-cohesive sediment transport, long-shore current and littoral drift, coastline evolution, crossshore profile evolution, the development of the coastline position in time.

Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

NASA Astrophysics Data System (ADS)

Sparkes, Robert B.; Doğrul Selver, Ayça; Gustafsson, Örjan; Semiletov, Igor P.; Haghipour, Negar; Wacker, Lukas; Eglinton, Timothy I.; Talbot, Helen M.; van Dongen, Bart E.

2016-10-01

Mobilisation of terrestrial organic carbon (terrOC) from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS). Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis-gas chromatography-mass spectrometry (py-GCMS) to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p < 0.01, n = 24). Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (14COC) which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river-ocean transects of surface sediments transition from river-dominated to coastal-erosion-dominated to marine-dominated signatures.

[Spatiotemporal variation of typical red soil eroded landscape pattern: a case study in Changting County of Fujian Province].

PubMed

Wu, Guo-sheng; Lin, Hui-hua; Zhu, He-jian; Sha, Jin-ming; Dai, Wen-yuan

2011-07-01

Based on the 1988, 2000, and 2007 remote sensing images of a typical red soil eroded region (Changting County, Fujian Province) and the digital elevation model (DEM), the eroded landscape types were worked out, and the changes of the eroded landscape pattern in the region from 1988 to 2007 were analyzed with the spatial mathematics model. In 1988-2007, different eroded landscape types in the region had the characteristics of inter-transfer, mainly manifested in the transfer from seriously eroded to lightly eroded types but still existed small amount of the transference from lightly eroded to seriously eroded types. Little change was observed in the controid of the eroded landscape. In the County, Hetian Town was all along the eroded center. During the study period, the landscape pattern index showed a tendency of low heterogeneity, low fragmentation, and high regularization at landscape level, but an overall improvement and expansion of lightly eroded and easy-to-tackle patches as well as the partial improvement and fragmentation of seriously eroded and difficult-to-tackle patches at patch level.

Coastline detection with time series of SAR images

NASA Astrophysics Data System (ADS)

Ao, Dongyang; Dumitru, Octavian; Schwarz, Gottfried; Datcu, Mihai

2017-10-01

For maritime remote sensing, coastline detection is a vital task. With continuous coastline detection results from satellite image time series, the actual shoreline, the sea level, and environmental parameters can be observed to support coastal management and disaster warning. Established coastline detection methods are often based on SAR images and wellknown image processing approaches. These methods involve a lot of complicated data processing, which is a big challenge for remote sensing time series. Additionally, a number of SAR satellites operating with polarimetric capabilities have been launched in recent years, and many investigations of target characteristics in radar polarization have been performed. In this paper, a fast and efficient coastline detection method is proposed which comprises three steps. First, we calculate a modified correlation coefficient of two SAR images of different polarization. This coefficient differs from the traditional computation where normalization is needed. Through this modified approach, the separation between sea and land becomes more prominent. Second, we set a histogram-based threshold to distinguish between sea and land within the given image. The histogram is derived from the statistical distribution of the polarized SAR image pixel amplitudes. Third, we extract continuous coastlines using a Canny image edge detector that is rather immune to speckle noise. Finally, the individual coastlines derived from time series of .SAR images can be checked for changes.

Morphological Inheritance in Sandy Coastline Morphologies Subject to Long-Term Changes in Wave Climate: Surprising Insights from a Coastline Evolution Model

NASA Astrophysics Data System (ADS)

Murray, A. B.; Thomas, C.; Hurst, M. D.; Barkwith, A.; Ashton, A. D.; Ellis, M. A.

2014-12-01

Recent numerical modelling demonstrates that when sandy coastlines are affected predominantly by waves approaching from "high" angles (> ~45° between the coastline and wave crests at the offshore limit of shore-parallel contours), large-scale (kms to 100 kms) morphodynamic instabilities and finite-amplitude interactions can lead to the emergence of striking coastline features, including sand waves, capes and spits. The type of feature that emerges depends on the wave climate, defined as the angular distribution of wave influences on alongshore sediment transport. Under a constant wave climate, coastline morphology reaches a dynamical steady state; the cross-shore/alongshore aspect ratio and the general appearance of the features remains constant. In previous modelling involving wave-climate change, as well as comparisons between observed coastline morphologies and wave climates, it has been implicitly assumed that the morphology adjusts in a quasi-equilibrium fashion, so that at any time the coastline shape reflects the current forcing. However, here we present new model results showing pronounced path dependence in coastline morphodynamics. In experiments with a period of constant wave climate followed by a period of transition to a new wave climate and then a run-on phase, the features that exist during the run-on phase can be qualitatively and quantitatively different from those that would develop initially under the final wave climate. Although the features inherited from the past wave-climate history may in some case be true alternate stable states, in other cases the inherited features gradually decay toward the morphology that would be expected given the final wave climate. A suite of such experiments allows us to characterize how the e-folding timescale of this decay depends on 1) the initial wave climate, 2) the path through wave-climate space, and 3) the rate of transition. When the initial features are flying spits with cross-shore amplitudes of 6 - 8 km, e-folding times can be on the order of millennia or longer. These results could provide a new perspective when interpreting current and past coastline features. In addition, the complex paleo-coastline structure that develops in the coastal hinterlands in these experiments could be relevant to the structures observed in some coastal environments.

Rebuilding natural coastlines after sediment mining: the example of the Brittany coasts (English Channel and Atlantic Ocean).

NASA Astrophysics Data System (ADS)

Regnauld, Herve

2016-04-01

Rebuilding natural coastlines after sediment mining: the example of the Brittany coasts (English Channel and Atlantic Ocean). H.Regnauld (1) , J.N. Proust (2) and H.Mahmoud (1) (1) University of Rennes 2, (2) CNRS-University of Rennes 1, France A large part of the coasts of Brittany (western France) have been very heavily impacted by sand mining for the building of military equipments and of a large tidal power station. In some places more then 90 % of the sediment has been extracted during the late 40ies up to the 60ies. The mined site were all sink sites, were sediment had been accumulating for centuries. After the sand and or gravel extraction was stopped the coastal sites were largely used for tourism and most of the eroded dune fields were turned into car parks. Storms produced large floods inland as most of the gravel or sand barrier didn't exist any more. Some local outcrops of inherited Holocene periglacial material with archaeological remains were eroded, some disappeared. During the 80ies a complete shift in planning policies took place and these sites were progressively changed into nature preserves. The aim was to make them behave in a "natural" way again. The "natural" behaviour was intended in a very precise way: barriers should be able to withstand storms again and to protect inland fields from floods. In order to allow for dune re building wooden fences were erected and marram grass was artificially planted. As, from a sedimentological point of view, these sites were sink sites, accumulation was rather rapid (up to 0.25m a year behind wooden fences) and new barrier began to build. The only problem is that they did not always build-up exactly in the same place or with the same material. Some parts of the coasts were left "unprotected" by these new barriers, ancient exposed sites became protected. Today the system as a whole may be considered as having been able to reach some level of equilibrium with the average wave conditions. It has been able to construct a real resilience if no intense event takes place. Though, as the storm frequency and direction has slightly changed the present system is not the equivalent of the former one. In Baie d'Audierne the new barrier is set in the same place but is totally different as it is not any more made of gravel but of sands. In Saint Malo, the new barriers are comprised of sands (as the ancient ones) but are not located in the same places. There is a site-specific way of reacting to human-related hazards and to organize resilience to natural hazards such as storms. Sedimentological analysis of cores in different sites allows reconstructing the ancient ways to react to storms and to compare it with the present one. Air photos analysis allows to precise the different steps of the re building after the sand and gravel mining ceased. This makes possible to compare the evolution of the sites on the long (centuries) and medium (decades) terms, before and after a drastic human impact. Though the system behaves now in a "natural" way, it must not be forgotten that large parts of the coasts, (especially cliffs carved into soft periglacial material) have irremediably been lost. Eroded sediment may be replaced by new sediment but the stratigraphical and archaeological information that was inside is definitively lost. It means that coast lines must not only be considered as changing dynamic elements with sediment fluxes but should also be thought of as in situ heritage sites with buried scientific data.

Extensive survey of terrestrial organic carbon in surface sediments of the East Siberian Sea

NASA Astrophysics Data System (ADS)

Vonk, Jorien; Gustafsson, Örjan; Alling, Vanja; Sánchez-García, Laura; van Dongen, Bart; Andersson, Per; Dudarev, Oleg; Semiletov, Igor; Eglinton, Tim

2010-05-01

The East Siberian Sea (ESS) is the largest and shallowest continental shelf sea of the Arctic Ocean, yet it is the least explored. The perenially frozen tundra and taiga of the circum-Arctic coastal area holds approximately half of the global belowground carbon pool. Significant amounts of terrestrial organic carbon (terrOC) are exported with the Great Siberian Arctic rivers to the shelf seas. In addition, the carbon-rich, ice-bound Yedoma coasts in East Siberia release significant amounts of Pleistocene carbon through thermal degradation and coastal erosion. The fate of these large-scale releases of terrOC in the East Siberian Shelf Sea is still poorly understood. The urgency of this research is accentuated by the fact that the East-Siberian Arctic landmass is experiencing the strongest climate warming on Earth, with a great potential for various carbon-climate feedback links. During the International Siberian Shelf Study 2008 (ISSS-08), a 50-day research expedition onboard the Russian vessel Yakob Smirnitskiy in late summer 2008, we obtained surface sediments from over 60 ESS locations. The data obtained after bulk analyses of these sediments are combined with results obtained from previous ESS campaigns in 2003 and 2004 to facilitate a comprehensive investigation of the ESS surface sediment composition. Sedimentary OC contents were between 0.13 and 3.7% (median 1.02%, interquartile range 0.563) with the highest values near the Indigirka and Kolyma river mouths and in the Long Strait. Stable carbon isotope values were in the range of -27.4 to -21.2 per mill (median -25.3 per mill, interquartile range 2.04), with more depleted values close to the coast. A clear transition was observed east of 170° E with more enriched values, signalling a regime shift with stronger influence of the Pacific Ocean. The terrOC fraction in the surface sediments was estimated from the 13C data to be on average 70% for ESS as a whole, with maximal values of 90-100% (along most of the coastline and in Sannikov and Dmitry Laptev Strait) and minimal values of 10-35% (outer shelf and Long Strait). An extensive set of bulk organic 14C data of the sedimentary OC in the ESS will also be interpreted with respect to relative contributions of coastal Yedoma erosion versus river input. Based on published and calculated (calculated from ISSS08 sediment cores) sedimentation velocities, we estimated terrOC burial sink on the East Siberian Shelf Sea.

Space-time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay and adjacent part of the Laptev Sea

NASA Astrophysics Data System (ADS)

Semiletov, I. P.; Shakhova, N. E.; Pipko, I. I.; Pugach, S. P.; Charkin, A. N.; Dudarev, O. V.; Kosmach, D. A.; Nishino, S.

2013-09-01

This study aims to improve understanding of carbon cycling in the Buor-Khaya Bay (BKB) and adjacent part of the Laptev Sea by studying the inter-annual, seasonal, and meso-scale variability of carbon and related hydrological and biogeochemical parameters in the water, as well as factors controlling carbon dioxide (CO2) emission. Here we present data sets obtained on summer cruises and winter expeditions during 12 yr of investigation. Based on data analysis, we suggest that in the heterotrophic BKB area, input of terrestrially borne organic carbon (OC) varies seasonally and inter-annually and is largely determined by rates of coastal erosion and river discharge. Two different BKB sedimentation regimes were revealed: Type 1 (erosion accumulation) and Type 2 (accumulation). A Type 1 sedimentation regime occurs more often and is believed to be the quantitatively most important mechanism for suspended particular matter (SPM) and particulate organic carbon (POC) delivery to the BKB. The mean SPM concentration observed in the BKB under a Type 1 regime was one order of magnitude greater than the mean concentration of SPM (~ 20 mg L-1) observed along the Lena River stream in summer 2003. Loadings of the BKB water column with particulate material vary by more than a factor of two between the two regimes. Higher partial pressure of CO2 (pCO2), higher concentrations of nutrients, and lower levels of oxygen saturation were observed in the bottom water near the eroded coasts, implying that coastal erosion and subsequent oxidation of eroded organic matter (OM) rather than the Lena River serves as the predominant source of nutrients to the BKB. Atmospheric CO2 fluxes from the sea surface in the BKB vary from 1 to 95 mmol m-2 day-1 and are determined by specific features of hydrology and wind conditions, which change spatially, seasonally, and inter-annually. Mean values of CO2 emission from the shallow Laptev Sea were similar in September 1999 and 2005 (7.2 and 7.8 mmol m-2 day-1, respectively), while the CO2 efflux can be one order lower after a strong storm such as in September 2011. Atmospheric CO2 emissions from a thawed coastal ice complex in the BKB area varied from 9 to 439 mmol m-2 day-1, with the mean value ranged from 75.7 to 101 mmol m-2 day-1 in two years (September 2006 and 2009), suggesting that at the time of observations the eroded coastal area served as a more significant source of CO2 to the atmosphere than the tundra (mean value: 22.7 mmol m-2 day-1) on the neighboring Primorsky coastal plain (September 2006). The observed increase in the Lena River discharge since the 1990s suggests that increased levels of "satellite-derived" annual primary production could be explained by an increasing load of humic acids delivered to shelf water; in this water the color resulting from the presence of CDOM (colored dissolved organic matter) mimics the color resulting from the presence of Chl a when seen from space. Because the BKB area can be employed as an integrator of ongoing changes in the surrounding environment, we suggest that under ongoing changes, more nutrients, products of eroded OC transformation and river transport, will be delivered to the Arctic Ocean with its shrinking ice cover, potentially increasing primary production outside of the shallow East Siberian Arctic Shelf (ESAS). At the same time, because the ESAS is characterized by very low transparency which limits euphotic layer thickness, excessive pCO2 will not be utilized by photosynthesis but will rather be emitted to the atmosphere at increasing rates, affecting regional CO2 balance.

Extraction of Coastlines with Fuzzy Approach Using SENTINEL-1 SAR Image

NASA Astrophysics Data System (ADS)

Demir, N.; Kaynarca, M.; Oy, S.

2016-06-01

Coastlines are important features for water resources, sea products, energy resources etc. Coastlines are changed dynamically, thus automated methods are necessary for analysing and detecting the changes along the coastlines. In this study, Sentinel-1 C band SAR image has been used to extract the coastline with fuzzy logic approach. The used SAR image has VH polarisation and 10x10m. spatial resolution, covers 57 sqkm area from the south-east of Puerto-Rico. Additionally, radiometric calibration is applied to reduce atmospheric and orbit error, and speckle filter is used to reduce the noise. Then the image is terrain-corrected using SRTM digital surface model. Classification of SAR image is a challenging task since SAR and optical sensors have very different properties. Even between different bands of the SAR sensors, the images look very different. So, the classification of SAR image is difficult with the traditional unsupervised methods. In this study, a fuzzy approach has been applied to distinguish the coastal pixels than the land surface pixels. The standard deviation and the mean, median values are calculated to use as parameters in fuzzy approach. The Mean-standard-deviation (MS) Large membership function is used because the large amounts of land and ocean pixels dominate the SAR image with large mean and standard deviation values. The pixel values are multiplied with 1000 to easify the calculations. The mean is calculated as 23 and the standard deviation is calculated as 12 for the whole image. The multiplier parameters are selected as a: 0.58, b: 0.05 to maximize the land surface membership. The result is evaluated using airborne LIDAR data, only for the areas where LIDAR dataset is available and secondly manually digitized coastline. The laser points which are below 0,5 m are classified as the ocean points. The 3D alpha-shapes algorithm is used to detect the coastline points from LIDAR data. Minimum distances are calculated between the LIDAR points of coastline with the extracted coastline. The statistics of the distances are calculated as following; the mean is 5.82m, standard deviation is 5.83m and the median value is 4.08 m. Secondly, the extracted coastline is also evaluated with manually created lines on SAR image. Both lines are converted to dense points with 1 m interval. Then the closest distances are calculated between the points from extracted coastline and manually created coastline. The mean is 5.23m, standard deviation is 4.52m. and the median value is 4.13m for the calculated distances. The evaluation values are within the accuracy of used SAR data for both quality assessment approaches.

I: Biomarker quantification in fish exposed to crude oil as input to species sensitivity distributions and threshold values for environmental monitoring.

PubMed

Sanni, Steinar; Björkblom, Carina; Jonsson, Henrik; Godal, Brit F; Liewenborg, Birgitta; Lyng, Emily; Pampanin, Daniela M

2017-04-01

The aim of this study was to determine a suitable set of biomarker based methods for environmental monitoring in sub-arctic and temperate offshore areas using scientific knowledge on the sensitivity of fish species to dispersed crude oil. Threshold values for environmental monitoring and risk assessment were obtained based on a quantitative comparison of biomarker responses. Turbot, halibut, salmon and sprat were exposed for up to 8 weeks to five different sub-lethal concentrations of dispersed crude oil. Biomarkers assessing PAH metabolites, oxidative stress, detoxification system I activity, genotoxicity, immunotoxicity, endocrine disruption, general cellular stress and histological changes were measured. Results showed that PAH metabolites, CYP1A/EROD, DNA adducts and histopathology rendered the most robust results across the different fish species, both in terms of sensitivity and dose-responsiveness. The reported results contributed to forming links between biomonitoring and risk assessment procedures by using biomarker species sensitivity distributions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil.

PubMed

Stige, Leif Chr; Ottersen, Geir; Yaragina, Natalia A; Vikebø, Frode B; Stenseth, Nils Chr; Langangen, Øystein

2018-04-01

It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959-1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills. Copyright © 2018 Elsevier Ltd. All rights reserved.

Monitoring the coastline change of Hatiya Island in Bangladesh using remote sensing techniques

NASA Astrophysics Data System (ADS)

Ghosh, Manoj Kumer; Kumar, Lalit; Roy, Chandan

2015-03-01

A large percentage of the world's population is concentrated along the coastal zones. These environmentally sensitive areas are under intense pressure from natural processes such as erosion, accretion and natural disasters as well as anthropogenic processes such as urban growth, resource development and pollution. These threats have made the coastal zone a priority for coastline monitoring programs and sustainable coastal management. This research utilizes integrated techniques of remote sensing and geographic information system (GIS) to monitor coastline changes from 1989 to 2010 at Hatiya Island, Bangladesh. In this study, satellite images from Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) were used to quantify the spatio-temporal changes that took place in the coastal zone of Hatiya Island during the specified period. The modified normalized difference water index (MNDWI) algorithm was applied to TM (1989 and 2010) and ETM (2000) images to discriminate the land-water interface and the on-screen digitizing approach was used over the MNDWI images of 1989, 2000 and 2010 for coastline extraction. Afterwards, the extent of changes in the coastline was estimated through overlaying the digitized maps of Hatiya Island of all three years. Coastline positions were highlighted to infer the erosion/accretion sectors along the coast, and the coastline changes were calculated. The results showed that erosion was severe in the northern and western parts of the island, whereas the southern and eastern parts of the island gained land through sedimentation. Over the study period (1989-2010), this offshore island witnessed the erosion of 6476 hectares. In contrast it experienced an accretion of 9916 hectares. These erosion and accretion processes played an active role in the changes of coastline during the study period.

Long-term rocky coast erosion: the influence of structural pattern and lithological context, as evidenced in the chalk (NW Normandy) and granitic (SW Brittany) rocks, NW France

NASA Astrophysics Data System (ADS)

Duperret, Anne; Raimbault, Céline; Duguet, Timothée; Le Gall, Bernard; Costa, Stéphane; Vandycke, Sara

2017-04-01

During the EC2CO/DRIL/CROCODYL project, high-resolution land-sea DEM have been produced in NW Normandy and SW Brittany rocky coastal zone, using high-resolution bathymetry from shallow-water cruises CROCOLIT-1,-2,-3 (Duperret, 2013), SPLASHALIOT-3 (Maillet, 2014), THAPENFROM-1 (Duperret, 2015) and aerial topographic LiDAR data from the Litto3D project. Two study sites were selected to map detailed geomorphology of shore platforms in order to better understand rock coast evolution processes through time and long-term rates of rocky coastal erosion versus geological context. The eastern English Channel is made of coastal chalk cliffs that currently eroding with fast mean rates of the order of a few dm/year. In Normandy coast (NW France), this results to the generation of roughly linear coastal segments of about 20-30km long each. On coastal segments only made of Upper Cretaceous Chalk, erosion occurs by present-day sudden and repeated vertical failures and cliff collapses. Cliff collapse process is shaping vertical chalk cliffs in association with resulting roughly flat shore platforms. Even if shore platforms width are short and homogeneous (a few hundred meters in width), the detailed morphology observed on high-resolution bathymetry evidenced two main submarine geomorphological types. One is linear and regular and associated with linear coastal sections. This corresponds to homogeneous Chalk Formation and the lack of large-scale tectonic features. Coastal sections with chalk lithology variations, local folding, large-scale fractures transverse-oriented to the coastline and onshore valleys incision evidence chaotic shore platforms morphologies. They conduct to variations in coastline orientation and to meter-scale shoreline indentations The southwestern part of Brittany is made of low-lying granitic headland and indented bay cut into meta/granitic rocks. Erosion rates are poorly known, due to slow coastal evolutions through contemporary times. Land-Sea DEM evidence similar onshore and offshore morphologies, with flat and wide superposed plains, limited each one by 10m high scarps. In this case, shore platform extension reaches a few km in width and appears as superposed paleo-shore platforms generated since Pleistocene (Raimbault et al, in press). The erosive process is thus link to a long-term alteration of granitic rocks since Cenozoic, mainly clear and etched during recent past high sea levels. Coastal areas with large bays appear locally to be guided by large-scale Cenozoic fractures. In some places, km-scale fractures favor a spatial concentration of erosion. They are shaping coastline orientation and shore platform ending at km-scale.

Late Quaternary sea-ice history of northern Fram Strait/Arctic Ocean

NASA Astrophysics Data System (ADS)

Kremer, Anne; Stein, Rüdiger; Fahl, Kirsten; Matthießen, Jens; Forwick, Matthias; O'Regan, Matt

2016-04-01

One of the main characteristics of the Arctic Ocean is its seasonal to perennial sea-ice cover. Variations of sea-ice conditions affect the Earth's albedo, primary production, rate of deep-water etc.. During the last decades, a drastic decrease in sea ice has been recorded, and the causes of which, i.e., natural vs. anthropogenic forcings, and their relevance within the global climate system, are subject of intense scientific and societal debate. In this context, records of past sea-ice conditions going beyond instrumental records are of major significance. These records may help to better understand the processes controlling natural sea-ice variability and to improve models for forecasts of future climatic conditions. During RV Polarstern Cruise PS92 in summer 2015, a 860 cm long sediment core (PS92/039-2) was recovered from the eastern flank of Yermak Plateau north of the Svalbard archipelago (Peeken, 2015). Based on a preliminary age model, this sediment core probably represents the time interval from MIS 6 to MIS 1. This core, located close to the modern summer ice edge, has been selected for reconstruction of past Arctic sea-ice variability based on specific biomarkers. In this context, we have determined the ice-algae-derived sea-ice proxy IP25 (Belt et al., 2007), in combination with other biomarkers indicative for open-water conditions (cf., Müller et al., 2009, 2011). Furthermore, organic carbon fluxes were differentiated using specific biomarkers indicative for marine primary production (brassicasterol, dinosterol) and terrigenous input (campesterol, β-sitosterol). In this poster, preliminary results of our organic-geochemical and sedimentological investigations are presented. Distinct fluctuations of these biomarkers indicate several major, partly abrupt changes in sea-ice cover in the Yermak Plateau area during the late Quaternary. These changes are probably linked to changes in the inflow of Atlantic Water along the western coastline of Svalbard into the Arctic Ocean. Furthermore, the repetitive advance and retreat of the Svalbard Barents Sea Ice Sheet might have influenced the terrigenous input and the environmental setting north of Svalbard, as reflected in the sediment composition of Core PS92/039-2. References Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of paleo sea ice: IP25. Organic Geochemistry 38, 16-27. Müller, J., Massé, G., Stein, R., Belt, S.T., 2009. Variability of sea-ice conditions in the Fram Strait over the past 30,000 years. Nature Geoscience 2 (11), 772-776. Müller, J., Wagner, A., Fahl, K., Stein, R., Prange, M., Lohmann, G., 2011. Towards quantitative sea ice reconstructions in the northern North Atlantic: a combined biomarker and numerical modelling approach. Earth and Planetary Science Letters 306 (3,4), 137-148. Peeken, I. (Ed.), 2015. Cruise report of Arctic Expedition PS92: TRANSSIZ Cruise from Bremerhaven to Longyearbyen (19.05.2015 - 28.06.2015), in preparation.

Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain.

PubMed

Hurst, Martin D; Rood, Dylan H; Ellis, Michael A; Anderson, Robert S; Dornbusch, Uwe

2016-11-22

Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured 10 Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The 10 Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cm⋅y -1 ) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cm⋅y -1 ). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.

Digital shoreline analysis system-based change detection along the highly eroding Krishna-Godavari delta front

NASA Astrophysics Data System (ADS)

Kallepalli, Akhil; Kakani, Nageswara Rao; James, David B.; Richardson, Mark A.

2017-07-01

Coastal regions are highly vulnerable to rising sea levels due to global warming. Previous Intergovernmental Panel on Climate Change (2013) predictions of 26 to 82 cm global sea level rise are now considered conservative. Subsequent investigations predict much higher levels which would displace 10% of the world's population living less than 10 m above sea level. Remote sensing and GIS technologies form the mainstay of models on coastal retreat and inundation to future sea-level rise. This study estimates the varying trends along the Krishna-Godavari (K-G) delta region. The rate of shoreline shift along the 330-km long K-G delta coast was estimated using satellite images between 1977 and 2008. With reference to a selected baseline from along an inland position, end point rate and net shoreline movement were calculated using a GIS-based digital shoreline analysis system. The results indicated a net loss of about 42.1 km2 area during this 31-year period, which is in agreement with previous literature. Considering the nature of landforms and EPR, the future hazard line (or coastline) is predicted for the area; the predication indicates a net erosion of about 57.6 km2 along the K-G delta coast by 2050 AD.

Intensified coastal development behind nourished beaches

NASA Astrophysics Data System (ADS)

Armstrong, Scott; Lazarus, Eli; Limber, Patrick; Goldstein, Evan; Thorpe, Curtis; Ballinger, Rhoda

2016-04-01

Population density, housing development, and property values in coastal counties along the U.S. Atlantic and Gulf Coasts continue to rise despite increasing hazard from storm impacts. Since the 1970s, beach nourishment, which involves importing sand to deliberately widen an eroding beach, has been the main strategy in the U.S. for protecting coastal properties from erosion and flooding hazards. Paradoxically, investment in hazard protection may intensify development. Here, we examine the housing stock of all existing shorefront single-family homes in Florida - a microcosm of U.S. coastal hazards and development - to quantitatively compare development in nourishing and non-nourishing towns. We find that nourishing towns now account for more than half of Florida's coastline, and that houses in nourishing towns are larger and more numerous. Even as the mean size of single-family homes nationwide has grown steadily since 1970, Florida's shorefront stock has exceeded the national average by 34%, and in nourishing towns by 45%. This emergent disparity between nourishing and non-nourishing towns in Florida demonstrates a pattern of intensifying coastal risk, and is likely representative of a dominant trend in coastal development more generally. These data lend empirical support to the hypothesis that US coastal development and hazard mitigation through beach nourishment have become dynamically coupled.

Automated Techniques for Quantification of Coastline Change Rates using Landsat Imagery along Caofeidian, China

NASA Astrophysics Data System (ADS)

Dong, Di; Li, Ziwei; Liu, Zhaoqin; Yu, Yang

2014-03-01

This paper focuses on automated extraction and monitoring of coastlines by remote sensing techniques using multi-temporal Landsat imagery along Caofeidian, China. Caofeidian, as one of the active economic regions in China, has experienced dramatic change due to enhanced human activities, such as land reclamation. These processes have caused morphological changes of the Caofeidian shoreline. In this study, shoreline extraction and change analysis are researched. An algorithm based on image texture and mathematical morphology is proposed to automate coastline extraction. We tested this approach and found that it's capable of extracting coastlines from TM and ETM+ images with little human modifications. Then, the detected coastline vectors are imported into Arcgis software, and the Digital Shoreline Analysis System (DSAS) is used to calculate the change rate (the end point rate and linear regression rate). The results show that in some parts of the research area, remarkable coastline changes are observed, especially the accretion rate. The abnormal accretion is mostly attributed to the large-scale land reclamation during 2003 and 2004 in Caofeidian. So we can conclude that various construction projects, especially the land reclamation project, have made Caofeidian shorelines change greatly, far above the normal.

Coastline evolution of Portuguese low-lying sandy coast in the last 50 years: an integrated approach

NASA Astrophysics Data System (ADS)

Ponte Lira, Cristina; Nobre Silva, Ana; Taborda, Rui; Freire de Andrade, Cesar

2016-06-01

Regional/national-scale information on coastline rates of change and trends is extremely valuable, but these studies are scarce. A widely accepted standardized methodology for analysing long-term coastline change has been difficult to achieve, but it is essential to conduct an integrated and holistic approach to coastline evolution and hence support coastal management actions. Additionally, databases providing knowledge on coastline evolution are of key importance to support both coastal management experts and users.The main objective of this work is to present the first systematic, national-scale and consistent long-term coastline evolution data of Portuguese mainland low-lying sandy coasts.The methodology used quantifies coastline evolution using a unique and robust coastline indicator (the foredune toe), which is independent of short-term changes.The dataset presented comprises (1) two polyline sets, mapping the 1958 and 2010 sandy beach-dune system coastline, both optimized for working at 1 : 50 000 scale or smaller; (2) one polyline set representing long-term change rates between 1958 and 2010, each estimated at 250 m; and (3) a table with minimum, maximum and mean of evolution rates for sandy beach-dune system coastline. All science data produced here are openly accessible at https://doi.pangaea.de/10.1594/PANGAEA.859136 and can be used in other studies.Results show beach erosion as the dominant trend, with a mean change rate of -0.24 ± 0.01 m year-1 for all mainland Portuguese beach-dune systems. Although erosion is dominant, this evolution is variable in signal and magnitude in different coastal sediment cells and also within each cell. The most relevant beach erosion issues were found in the coastal stretches of Espinho-Torreira and Costa Nova-Praia de Mira, Cova da Gala-Leirosa, and Cova do Vapor-Costa da Caparica. The coastal segments Minho River-Nazaré and Costa da Caparica adjacent to the coast exhibit a history of major human interventions interfering with the coastal system, many of which originated and maintained a sediment deficit. In contrast, the coastal segments Troia-Sines and Sines-Cape S. Vicente have experienced less intervention and show stable or moderate accretion behaviour.

The global coastline dataset: the observed relation between erosion and sea-level rise

NASA Astrophysics Data System (ADS)

Donchyts, G.; Baart, F.; Luijendijk, A.; Hagenaars, G.

2017-12-01

Erosion of sandy coasts is considered one of the key risks of sea-level rise. Because sandy coastlines of the world are often highly populated, erosive coastline trends result in risk to populations and infrastructure. Most of our understanding of the relation between sea-level rise and coastal erosion is based on local or regional observations and generalizations of numerical and physical experiments. Until recently there was no reliable global scale assessment of the location of sandy coasts and their rate of erosion and accretion. Here we present the global coastline dataset that covers erosion indicators on a local scale with global coverage. The dataset uses our global coastline transects grid defined with an alongshore spacing of 250 m and a cross shore length extending 1 km seaward and 1 km landward. This grid matches up with pre-existing local grids where available. We present the latest results on validation of coastal-erosion trends (based on optical satellites) and classification of sandy versus non-sandy coasts. We show the relation between sea-level rise (based both on tide-gauges and multi-mission satellite altimetry) and observed erosion trends over the last decades, taking into account broken-coastline trends (for example due to nourishments).An interactive web application presents the publicly-accessible results using a backend based on Google Earth Engine. It allows both researchers and stakeholders to use objective estimates of coastline trends, particularly when authoritative sources are not available.

The use of time-series LIDAR to understand the role of foredune blowouts in coastal dune dynamics, Sefton, NW England.

NASA Astrophysics Data System (ADS)

O'Keeffe, Nicholas; Delgado-Fernandez, Irene; Aplin, Paul; Jackson, Derek; Marston, Christopher

2017-04-01

Coastal dunes are natural buffers against the threat of climate change-induced sea level rise. Their evolution is largely controlled by sediment exchanges between the geomorphic sub-units of the nearshore, beach, foredune and dune field. Coastlines characterised by multiple blowouts at the beach-dune interface may be more susceptible to coastline retreat through the enhanced landwards transport of beach and foredune sediment. This study, based in Sefton, north-west England, exploits an unprecedented temporal coverage of LIDAR surveys spanning 15 years (1999, 2008, 2010, 2013 and 2014). Established GIS techniques have been utilised to extract both the coastline (foredune toe) and the foredune crest from each LIDAR derived DTM (Digital Terrain Model). Migration of the foredune toe has been tracked over this period. Analysis of differentials between the height of the dune toe and dune crest have been used to locate the alongshore position of blowouts within the foredune. Dune sediment budgets have then been calculated for each DTM and analysis of the budgets conducted, with the coastline being compartmentalised alongshore, based on presence of blowouts within the foredune. Results indicate that sections of the coastline where blowouts are present within the foredune may be most vulnerable to coastline retreat. Temporal changes in the sediment budget within many of these sections also provides evidence that, if blowouts are present, coastline retreat continues to be a possibility even when the dune sediment budget remains positive.

Newly identified "Tunnunik" impact structure, Prince Albert Peninsula, northwestern Victoria Island, Arctic Canada

NASA Astrophysics Data System (ADS)

Dewing, Keith; Pratt, Brian R.; Hadlari, Thomas; Brent, Tom; BÉDard, Jean; Rainbird, Robert H.

2013-02-01

Regional geological mapping of the glaciated surface of northwestern Victoria Island in the western Canadian Arctic revealed an anomalous structure in otherwise flat-lying Neoproterozoic and lower Paleozoic carbonate rocks, located south of Richard Collinson Inlet. The feature is roughly circular in plan view, approximately 25 km in diameter, and characterized by quaquaversal dips of approximately 45°, decreasing laterally. The core of the feature also exhibits local vertical dips, low-angle reverse faults, and drag folds. Although brecciation was not observed, shatter cones are pervasive in all lithologies in the central area, including 723 Ma old dikes that penetrate Neoproterozoic limestones. Their abundance decreases distally, and none was observed in surrounding, horizontally bedded strata. This circular structure is interpreted as a deeply eroded meteorite impact crater of the complex type, and the dipping strata as the remnants of the central uplift. The variation in orientation and shape of shatter cones point to variably oriented stresses with the passage of the shock wave, possibly related to the presence of pore water in the target strata as well as rock type and lithological heterogeneities, especially bed thickness. Timing of impact is poorly constrained. The youngest rocks affected are Late Ordovician (approximately 450 Ma) and the impact structure is mantled by undisturbed postglacial sediments. Regional, hydrothermal dolomitization of the Ordovician limestones, possibly in the Late Devonian (approximately 360 Ma), took place before the impact, and widespread WSW-ENE-trending normal faults of probable Early Cretaceous age (approximately 130 Ma) apparently cross-cut the impact structure.

Systematic Analysis of Rocky Shore Morphology along 700km of Coastline Using LiDAR-derived DEMs

NASA Astrophysics Data System (ADS)

Matsumoto, H.; Dickson, M. E.; Masselink, G.

2016-12-01

Rock shore platforms occur along much of the world's coast and have a long history of study; however, uncertainty remains concerning the relative importance of various formative controls in different settings (e.g. wave erosion, weathering, tidal range, rock resistance, inheritance). Ambiguity is often attributed to intrinsic natural variability and the lack of preserved evidence on eroding rocky shores, but it could also be argued that previous studies are limited in scale, focusing on a small number of local sites, which restricts the potential for insights from broad, regional analyses. Here we describe a method, using LiDAR-derived digital elevation models (DEMs), for analysing shore platform morphology over an unprecedentedly wide area in which there are large variations in environmental conditions. The new method semi-automatically extracts shore platform profiles and systematically conducts morphometric analysis. We apply the method to 700 km of coast in the SW UK that is exposed to (i) highly energetic swell waves to local wind waves, (ii) macro to mega tidal ranges, and (iii) highly resistant igneous rocks to moderately hard sedimentary rocks. Computer programs are developed to estimate mean sea level, mean spring tidal range, wave height, and rock strength along the coastline. Filtering routines automatically select and remove profiles that are unsuitable for analysis. The large data-set of remaining profiles supports broad and systematic investigation of possible controls on platform morphology. Results, as expected, show wide scatter, because many formative controls are in play, but several trends exist that are generally consistent with relationships that have been inferred from local site studies. This paper will describe correlation analysis on platform morphology in relation to environmental conditions and also present a multi-variable empirical model derived from multi linear regression analysis. Interesting matches exist between platform gradients obtained from the field, and empirical model predictions, particularly when morphological variability found in LiDAR-based shore platform morphology analysis is considered. These findings frame a discussion on formative controls of rocky shore morphology.

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

7 CFR 12.21 - Identification of highly erodible lands criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Basis for identification as highly erodible. Soil map units and an erodibility index will be used as the basis for identifying highly erodible land. The erodibility index for a soil is determined by dividing the potential average annual rate of erosion for each soil by its predetermined soil loss tolerance (T...

Ethoxyresorufin-O-deethylase (EROD) activity in fish as a biomarker of chemical exposure

USGS Publications Warehouse

Whyte, J.J.; Jung, R.E.; Schmitt, C.J.; Tillitt, D.E.

2000-01-01

This review compiles and evaluates existing scientific information on the use, limitations, and procedural considerations for EROD activity (a catalytic measurement of cytochrome P4501A induction) as a biomarker in fish. A multitude of chemicals induce EROD activity in a variety of fish species, the most potent inducers being structural analogs of 2,3,7,8-tetracholordibenzo-p-dioxin. Although certain chemicals may inhibit EROD induction/activity, this interference is generally not a drawback to the use of EROD induction as a biomarker. The various methods of EROD analysis currently in use yield comparable results, particularly when data are expressed as relative rates of EROD activity. EROD induction in fish is well characterized, the most important modifying factors being fish species, reproductive status and age, all of which can be controlled through proper study design. Good candidate species for biomonitoring should have a wide range between basal and induced EROD activity (e.g., common carp, channel catfish, and mummichog). EROD activity has proven value as a biomarker in a number of field investigations of bleached kraft mill and industrial effluents, contaminated sediments, and chemical spills. Research on mechanisms of CYP1A-induced toxicity suggests that EROD activity may not only indicate chemical exposure, but also may also precede effects at various levels of biological organization. A current research need is the development of chemical exposure-response relationships for EROD activity in fish. In addition, routine reporting in the literature of EROD activity in standard positive and negative control material will enhance confidence in comparing results from different studies using this biomarker.

Soil erodibility for water erosion: A perspective and Chinese experiences

NASA Astrophysics Data System (ADS)

Wang, Bin; Zheng, Fenli; Römkens, Mathias J. M.; Darboux, Frédéric

2013-04-01

Knowledge of soil erodibility is an essential requirement for erosion prediction, conservation planning, and the assessment of sediment related environmental effects of watershed agricultural practices. This paper reviews the status of soil erodibility evaluations and determinations based on 80 years of upland area erosion research mainly in China and the USA. The review synthesizes the general research progress made by discussing the basic concepts of erodibility and its evaluation, determination, and prediction as well as knowledge of its spatio-temporal variations. The authors found that soil erodibility is often inappropriately or inaccurately applied in describing soil loss caused by different soil erosion component processes and mechanisms. Soil erodibility indicators were related to intrinsic soil properties and exogenic erosional forces, measurements, and calculations. The present review describes major needs including: (1) improved definition of erodibility, (2) modified erodibility determinations in erosion models, especially for specific geographical locations and in the context of different erosion sub-processes, (3) advanced methodologies for quantifying erodibilities of different soil erosion sub-processes, and (4) a better understanding of the mechanism that causes temporal variations in soil erodibility. The review also provides a more rational basis for future research on soil erodibility and supports predictive modeling of soil erosion processes and the development of improved conservation practices.

Monitoring and Analyzing the Geospatial Patterns of the Pearl River Delta (prd) from 1960 TO 2012

NASA Astrophysics Data System (ADS)

Wang, J.; Wu, Z.; Li, S.; Cao, Z.

2018-04-01

The Geospatial Patterns Pearl River Delta (PRD), one of the most economically-important and fastest-growing regions in China, have changed remarkably and continuously during the past decades. In this research, the change of landuse, coastline during 1960-2012 were closely investigated to provide better description and explanation of the geospatial pattern. And the relationships between them were explored. Finally, the impact that urban expansion brought to the coastal environment was quantitatively analyzed. The main remarks of this research are summarized into the following points: (1) In PRD, construction land expanded 33 times. In the meantime, the area of forest and farmland decreased 47.53 % and 56.70 %, respectively. (2) The land demand for agricultural development was the key factor that changed coastline in PRD before 2000. Since 2000, land demand for urban construction has been the key factor that changed coastline in PRD. (3) During 1960 to 2012, the length of coastline in PRD increased from 1134.95 km to 1508.02 km with an increasing speed of 7.17 km per year. Relatively, the coastline changed more obvious in three periods (2004 to 2006, 2006 to 2008 and 2008 to 2010). (4) The type of coastline changed remarkably from 1960 to 2012. 82.94 % of the natural coastline in PRD disappeared until 2012. Known from this research, the geospatial patterns of the PRD changed remarkably during 1960 to 2012, mainly driven by human activities. The coastal environment is facing serious risks and challenges under the rapid process of urbanization.

The Influence of Soil Moisture, Coastline Curvature, and Land-Breeze Circulations on Sea-Breeze Initiated Precipitation

NASA Technical Reports Server (NTRS)

Baker, David R.; Lynn, Barry H.; Boone, Aaron; Tao, Wei-Kuo; Simpson, Joanne

2000-01-01

Idealized numerical simulations are performed with a coupled atmosphere/land-surface model to identify the roles of initial soil moisture, coastline curvature, and land breeze circulations on sea breeze initiated precipitation. Data collected on 27 July 1991 during the Convection and Precipitation Electrification Experiment (CAPE) in central Florida are used. The 3D Goddard Cumulus Ensemble (GCE) cloud resolving model is coupled with the Goddard Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model, thus providing a tool to simulate more realistically land-surface/atmosphere interaction and convective initiation. Eight simulations are conducted with either straight or curved coast-lines, initially homogeneous soil moisture or initially variable soil moisture, and initially homogeneous horizontal winds or initially variable horizontal winds (land breezes). All model simulations capture the diurnal evolution and general distribution of sea-breeze initiated precipitation over central Florida. The distribution of initial soil moisture influences the timing, intensity and location of subsequent precipitation. Soil moisture acts as a moisture source for the atmosphere, increases the connectively available potential energy, and thus preferentially focuses heavy precipitation over existing wet soil. Strong soil moisture-induced mesoscale circulations are not evident in these simulations. Coastline curvature has a major impact on the timing and location of precipitation. Earlier low-level convergence occurs inland of convex coastlines, and subsequent precipitation occurs earlier in simulations with curved coastlines. The presence of initial land breezes alone has little impact on subsequent precipitation. however, simulations with both coastline curvature and initial land breezes produce significantly larger peak rain rates due to nonlinear interactions.

Automated Generation of the Alaska Coastline Using High-Resolution Satellite Imagery

NASA Astrophysics Data System (ADS)

Roth, G.; Porter, C. C.; Cloutier, M. D.; Clementz, M. E.; Reim, C.; Morin, P. J.

2015-12-01

Previous campaigns to map Alaska's coast at high resolution have relied on airborne, marine, or ground-based surveying and manual digitization. The coarse temporal resolution, inability to scale geographically, and high cost of field data acquisition in these campaigns is inadequate for the scale and speed of recent coastal change in Alaska. Here, we leverage the Polar Geospatial Center (PGC) archive of DigitalGlobe, Inc. satellite imagery to produce a state-wide coastline at 2 meter resolution. We first select multispectral imagery based on time and quality criteria. We then extract the near-infrared (NIR) band from each processed image, and classify each pixel as water or land with a pre-determined NIR threshold value. Processing continues with vectorizing the water-land boundary, removing extraneous data, and attaching metadata. Final coastline raster and vector products maintain the original accuracy of the orthorectified satellite data, which is often within the local tidal range. The repeat frequency of coastline production can range from 1 month to 3 years, depending on factors such as satellite capacity, cloud cover, and floating ice. Shadows from trees or structures complicate the output and merit further data cleaning. The PGC's imagery archive, unique expertise, and computing resources enabled us to map the Alaskan coastline in a few months. The DigitalGlobe archive allows us to update this coastline as new imagery is acquired, and facilitates baseline data for studies of coastal change and improvement of topographic datasets. Our results are not simply a one-time coastline, but rather a system for producing multi-temporal, automated coastlines. Workflows and tools produced with this project can be freely distributed and utilized globally. Researchers and government agencies must now consider how they can incorporate and quality-control this high-frequency, high-resolution data to meet their mapping standards and research objectives.

Evaluating operational AVHRR sea surface temperature data at the coastline using surfers

NASA Astrophysics Data System (ADS)

Brewin, Robert J. W.; de Mora, Lee; Billson, Oliver; Jackson, Thomas; Russell, Paul; Brewin, Thomas G.; Shutler, Jamie D.; Miller, Peter I.; Taylor, Benjamin H.; Smyth, Tim J.; Fishwick, James R.

2017-09-01

Sea surface temperature (SST) is an essential climate variable that can be measured routinely from Earth Observation (EO) with high temporal and spatial coverage. To evaluate its suitability for an application, it is critical to know the accuracy and precision (performance) of the EO SST data. This requires comparisons with co-located and concomitant in situ data. Owing to a relatively large network of in situ platforms there is a good understanding of the performance of EO SST data in the open ocean. However, at the coastline this performance is not well known, impeded by a lack of in situ data. Here, we used in situ SST measurements collected by a group of surfers over a three year period in the coastal waters of the UK and Ireland, to improve our understanding of the performance of EO SST data at the coastline. At two beaches near the city of Plymouth, UK, the in situ SST measurements collected by the surfers were compared with in situ SST collected from two autonomous buoys located ∼7 km and ∼33 km from the coastline, and showed good agreement, with discrepancies consistent with the spatial separation of the sites. The in situ SST measurements collected by the surfers around the coastline, and those collected offshore by the two autonomous buoys, were used to evaluate the performance of operational Advanced Very High Resolution Radiometer (AVHRR) EO SST data. Results indicate: (i) a significant reduction in the performance of AVHRR at retrieving SST at the coastline, with root mean square errors in the range of 1.0 to 2.0 °C depending on the temporal difference between match-ups, significantly higher than those at the two offshore stations (0.4 to 0.6 °C); (ii) a systematic negative bias in the AVHRR retrievals of approximately 1 °C at the coastline, not observed at the two offshore stations; and (iii) an increase in the root mean square error at the coastline when the temporal difference between match-ups exceeded three hours. Harnessing new solutions to improve in situ sampling coverage at the coastline, such as tagging surfers with sensors, can improve our understanding of the performance of EO SST data in coastal regions, helping inform users interested in EO SST products for coastal applications. Yet, validating EO SST products using in situ SST data at the coastline is challenged by difficulties reconciling the two measurements, which are provided at different spatial scales in a dynamic and complex environment.

The Role of Biological Soil Crusts in Nitrogen Cycling and Soil Deflation in West Greenland

NASA Astrophysics Data System (ADS)

Heindel, R. C.; Governali, F. C.; Spickard, A. M.; Virginia, R. A.

2017-12-01

Although shrub expansion has been observed across the Arctic in moist tundra habitat, shrubs may be prevented from expanding in arid Arctic regions due to low soil moisture or soil erosion. This may be the case in Kangerlussuaq, West Greenland, where katabatic winds off the Greenland Ice Sheet have eroded distinct patches of mixed shrub tundra, resulting in nearly barren low productivity areas dominated by biological soil crusts (biocrusts) and graminoids. The future trajectory of these bare patches - persisting in a low biomass state or returning to a shrub-dominated state - depends on the role of the biocrust as either a long-term landscape cover limiting revegetation or as a successional facilitator. Prior to this study, little was known about the physical and ecological development of West Greenland biocrusts and how they may influence future vegetation dynamics. We found that biocrusts took 230 ± 48 years to fully develop, and that later stages of biocrust development were related to increased thickness and penetration resistance and decreased soil moisture, factors limiting shrub seedling establishment. The nitrogen (N) fixing lichen Stereocaulon sp. was found throughout the study region at all stages of biocrust development. Natural 15N abundance suggests that Stereocaulon sp. obtains about half of its N from biological fixation, and that some biologically-fixed N is incorporated into the underlying soils over time. Although soil N and C concentrations increased slightly with biocrust development, their levels under the most developed biocrusts remained low compared to the surrounding shrub and graminoid tundra. Our results suggest that deflation patches, triggered by long-term variations in climate, may remain in a low-productivity ecosystem state for hundreds to thousands of years, if precipitation and temperature regimes do not dramatically alter the vegetation potential of the region. However, if future climate change in the Arctic favors greater primary production, and the rate of soil deflation declines, then the productivity of the Kangerlussuaq tundra could increase, favoring a transition to a more vegetated and shrub-dominated landscape.

Applying transport-distance specific SOC distribution to calibrate soil erosion model WaTEM

NASA Astrophysics Data System (ADS)

Hu, Yaxian; Heckrath, Goswin J.; Kuhn, Nikolaus J.

2016-04-01

Slope-scale soil erosion, transport and deposition fundamentally decide the spatial redistribution of eroded sediments in terrestrial and aquatic systems, which further affect the burial and decomposition of eroded SOC. However, comparisons of SOC contents between upper eroding slope and lower depositional site cannot fully reflect the movement of eroded SOC in-transit along hillslopes. The actual transport distance of eroded SOC is decided by its settling velocity. So far, the settling velocity distribution of eroded SOC is mostly calculated from mineral particle specific SOC distribution. Yet, soil is mostly eroded in form of aggregates, and the movement of aggregates differs significantly from individual mineral particles. This urges a SOC erodibility parameter based on actual transport distance distribution of eroded fractions to better calibrate soil erosion models. Previous field investigation on a freshly seeded cropland in Denmark has shown immediate deposition of fast settling soil fractions and the associated SOC at footslopes, followed by a fining trend at the slope tail. To further quantify the long-term effects of topography on erosional redistribution of eroded SOC, the actual transport-distance specific SOC distribution observed on the field was applied to a soil erosion model WaTEM (based on USLE). After integrating with local DEM, our calibrated model succeeded in locating the hotspots of enrichment/depletion of eroded SOC on different topographic positions, much better corresponding to the real-world field observation. By extrapolating into repeated erosion events, our projected results on the spatial distribution of eroded SOC are also adequately consistent with the SOC properties in the consecutive sample profiles along the slope.

Climate change and the northern Russian treeline zone.

PubMed

MacDonald, G M; Kremenetski, K V; Beilman, D W

2008-07-12

The Russian treeline is a dynamic ecotone typified by steep gradients in summer temperature and regionally variable gradients in albedo and heat flux. The location of the treeline is largely controlled by summer temperatures and growing season length. Temperatures have responded strongly to twentieth-century global warming and will display a magnified response to future warming. Dendroecological studies indicate enhanced conifer recruitment during the twentieth century. However, conifers have not yet recolonized many areas where trees were present during the Medieval Warm period (ca AD 800-1,300) or the Holocene Thermal Maximum (HTM; ca 10,000-3,000 years ago). Reconstruction of tree distributions during the HTM suggests that the future position of the treeline due to global warming may approximate its former Holocene maximum position. An increased dominance of evergreen tree species in the northern Siberian forests may be an important difference between past and future conditions. Based on the slow rates of treeline expansion observed during the twentieth century, the presence of steep climatic gradients associated with the current Arctic coastline and the prevalence of organic soils, it is possible that rates of treeline expansion will be regionally variable and transient forest communities with species abundances different from today's may develop.

Processes Affecting the Annual Surface Energy Budget at High-Latitude Terrestrial Sites

NASA Astrophysics Data System (ADS)

Persson, P. O. G.; Stone, R. S.; Grachev, A.; Matrosova, L.

2012-04-01

Instrumentation at four Study of Environmental Arctic Change (SEARCH) sites (Barrow, Eureka, Alert, and Tiksi) have been enhanced in the past 6 years, including during the 2007-2008 IPY. Data from these sites are used to investigate the annual cycle of the surface energy budget (SEB), its coupling to atmospheric processes, and for Alert, its interannual variability. The comprehensive data sets are useful for showing interactions between the atmosphere, surface, and soil at high temporal resolution throughout the annual cycle. Processes that govern the SEB variability at each site are identified, and their impacts on the SEB are quantified. For example, mesoscale modulation of the SEB caused by forcing from the local terrain (downslope wind events) and coastlines (sea and land breezes) are significant at Alert and Eureka, with these processes affecting both radiative, turbulent, and ground heat flux terms in the SEB. Sub-seasonal and interannual variations in atmospheric processes and SEB impact soil thermal structures, such as the depth and timing of the summer active layer. These analyses provide an improved understanding of the processes producing changes in surface and soil temperature, linking them through the SEB as affected by atmospheric processes.

GIS-based analysis and modelling with empirical and remotely-sensed data on coastline advance and retreat

NASA Astrophysics Data System (ADS)

Ahmad, Sajid Rashid

With the understanding that far more research remains to be done on the development and use of innovative and functional geospatial techniques and procedures to investigate coastline changes this thesis focussed on the integration of remote sensing, geographical information systems (GIS) and modelling techniques to provide meaningful insights on the spatial and temporal dynamics of coastline changes. One of the unique strengths of this research was the parameterization of the GIS with long-term empirical and remote sensing data. Annual empirical data from 1941--2007 were analyzed by the GIS, and then modelled with statistical techniques. Data were also extracted from Landsat TM and ETM+ images. The band ratio method was used to extract the coastlines. Topographic maps were also used to extract digital map data. All data incorporated into ArcGIS 9.2 were analyzed with various modules, including Spatial Analyst, 3D Analyst, and Triangulated Irregular Networks. The Digital Shoreline Analysis System was used to analyze and predict rates of coastline change. GIS results showed the spatial locations along the coast that will either advance or retreat over time. The linear regression results highlighted temporal changes which are likely to occur along the coastline. Box-Jenkins modelling procedures were utilized to determine statistical models which best described the time series (1941--2007) of coastline change data. After several iterations and goodness-of-fit tests, second-order spatial cyclic autoregressive models, first-order autoregressive models and autoregressive moving average models were identified as being appropriate for describing the deterministic and random processes operating in Guyana's coastal system. The models highlighted not only cyclical patterns in advance and retreat of the coastline, but also the existence of short and long-term memory processes. Long-term memory processes could be associated with mudshoal propagation and stabilization while short-term memory processes were indicative of transitory hydrodynamic and other processes. An innovative framework for a spatio-temporal information-based system (STIBS) was developed. STIBS incorporated diverse datasets within a GIS, dynamic computer-based simulation models, and a spatial information query and graphical subsystem. Tests of the STIBS proved that it could be used to simulate and visualize temporal variability in shifting morphological states of the coastline.

Coastline change mapping using a spectral band method and Sobel edge operator

NASA Astrophysics Data System (ADS)

Al-Mansoori, Saeed; Al-Marzouqi, Fatima

2016-10-01

Coastline extraction has become an essential activity in wake of the natural disasters taking place in some regions such as tsunami, flooding etc. Salient feature of such catastrophes is lack of reaction time available for combating emergency, thus it is the endeavor of any country to develop constant monitoring mechanism of shorelines. This is a challenging task because of the magnitude of changes taking place to the coastline regularly. Previous research findings highlight a need of formulating automation driven methodology for timely and accurate detection of alterations in the coastline impacting sustainability of mankind operating in the coastal zone. In this study, we propose a new approach for automatic extraction of the coastline using remote sensing data. This approach is composed of three main stages. Firstly, classifying pixels of the image into two categories i.e. land and water body by applying two normalized difference indices i.e. Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI). Then, the process of binary conversion of classified image takes place using a local threshold method. Finally, the coastline is extracted by applying Sobel edge operator with a pair of (3×3) kernels. The approach is tested using 2.5m DubaiSat-1 (DS1) and DubaiSat-2 (DS2) images captured to detect and monitor the changes occurring along Dubai coastal zone within a period of six years from 2009 till 2015. Experimental results prove that the approach is capable of extracting the coastlines from DS1 and DS2 images with moderate human interaction. The results of the study show an increase of 6% in Dubai shoreline resulting on account of numerous man-made infrastructure development projects in tourism and allied sectors.

Aeolian transport of seagrass (Posidonia oceanica) beach-cast to terrestrial systems

NASA Astrophysics Data System (ADS)

Jiménez, Maria A.; Beltran, Rafel; Traveset, Anna; Calleja, Maria Ll; Delgado-Huertas, Antonio; Marbà, Núria

2017-09-01

The annual export of the Mediterranean seagrass (Posidonia oceanica) litter to adjacent beaches and coastal dunes was quantified by examining the fortnight evolution of seagrass beach-cast volume on two beaches in the NW Mediterranean (Son Real and Es Trenc, Mallorca Island, Spain) for two years and analyzing the wind speed and direction obtained from the closest Meteorological Spanish Agency surface weather stations. The decomposition stage of the deposits was examined by analyzing the total hydrolysable amino acids, its percentage distribution and derived degradation indexes. Prevalent winds exceeding 6 m s-1, the coastline morphology and type of terrestrial vegetation determine the annual dynamics of the seagrass beach-cast. In the most protected beach (Son Real) the seagrass beach-cast remained nearly stationary during the two studied years while it exhibited wide annual fluctuations in the less protected one (Es Trenc). The amounts of P. oceanica wrack washed on Son Real and Es Trenc beaches, respectively, were estimated at 309 kg DW m coastline-1 yr-1 and 1359 kg DW m coastline-1 yr-1. They supplied between 20 kg CaCO3 m coastline-1 yr-1 and 47 kg CaCO3 m coastline-1 yr-1. Between 54% (Son Real) and 70% (Es Trenc) of seagrass beach-cast, respectively accounting for 1.5 kg N m coastline-1 yr-1 and 8.6 kg N m coastline-1 yr-1, were annually exported from the beaches to adjacent dune systems. Our results reveal that Mediterranean seagrass meadows might be an important source of materials, including sand and nutrients, for adjacent terrestrial systems, able to support their functioning.

Deviations of Atmospheric Coastal Flow from the Open-channel Hydraulics Analogy

NASA Astrophysics Data System (ADS)

Rahn, D. A.; Parish, T. R.; Juliano, T. W.

2017-12-01

Low-level atmospheric flow along the coast of California bears resemblance to open-channel engineering applications referred to as hydraulic flow. During the warm season, strong equatorward wind is common near the surface. A marked temperature inversion separates the cool, moist marine air and the warm, dry free troposphere aloft. The low-level flow is bounded laterally by the coastal topography. Given the high wind speed in the shallow marine layer, the flow is often supercritical (Fr > 1). Features resembling oblique compression jumps and expansion fans occur near concave and convex bends in the coastline and impact wind energy production, wind stress on the ocean surface, and propagation of electromagnetic waves by modifying the vertical refractivity gradient. An aircraft collected fine-scale measurements offshore of southern California to test how well the observed features conform to the single-layer hydraulic approximation. Although the open-channel framework captures major features of the flow as indicated by prior work, the detailed measurements reveal when the analogy breaks down. The assumption of a passive upper layer can be violated due to mesoscale pressure gradients aloft and lee troughing associated with offshore flow, which can enhance the thinning of the marine layer associated with the expansion fan. The sharp interface between layers can be eroded when Ri becomes low, Kelvin-Helmholtz instability develops, and the structure of the lower atmosphere is drastically altered. This is poorly simulated in operational weather forecast models due to their relatively coarse grid spacing. The layer associated with the expansion fan rarely keeps its identity into the Santa Barbara Channel. An increase of surface heat flux and vertical mixing as the flow moves over warmer sea surface temperatures in the channel rapidly erodes the layer. Only one flight captured a hydraulic jump between the supercritical flow in the expansion fan and the subcritical flow downstream, but its features correspond well to predicted values. The lack of hydraulic jumps on other days is likely due to the loss of layer identity before the jump can be realized.

Are deep-sea organisms dwelling within a submarine canyon more at risk from anthropogenic contamination than those from the adjacent open slope? A case study of Blanes canyon (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Koenig, Samuel; Fernández, Pilar; Company, Joan B.; Huertas, David; Solé, Montserrat

2013-11-01

Due to their geomorphological structure and proximity to the coastline, submarine canyons may act as natural conduit routes for anthropogenic contaminants that are transported from surface waters to the deep-sea. Organisms dwelling in these canyon environments might thus be at risk of experiencing adverse health effects due to higher pollution exposure. To address this question, chemical and biochemical analyses were conducted on two of the most abundant deep-sea fish species in the study area, namely Alepocephalus rostratus and Lepidion lepidion, and the most abundant deep-sea commercial decapod crustacean Aristeus antennatus sampled inside Blanes canyon (BC) and on the adjacent open slope (OS). Persistent organic pollutants (POPs) levels, including polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT) and derivatives, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were determined in muscle tissue of selected samples from 900 m and 1500 m depth. Potential effects resulting from contaminant exposure were determined using hepatic biomarkers such as ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-deethylase (PROD), catalase (CAT), carboxylesterase (CbE), glutathione-S-transferase (GST), total glutathione peroxidase (GPX), glutathione reductase (GR) and superoxide-dismutase (SOD) enzyme activities and lipid peroxidation levels (LP). L. lepidion and A. antennatus tissues exhibited higher POP levels inside BC compared to the OS at 900 m depth. These findings were consistent with biomarker data (i.e. enzymatic response to presence of contaminant agents). Elevated xenobiotic-metabolizing (EROD and PROD) and antioxidant enzymes (CAT and GPX) indicated higher contaminant exposure in both species caught within BC. No difference in POP accumulation between sites was observed in L. lepidion at 1500 m depth, nor in biomarker data, suggesting that the pollution gradient was less pronounced at greater depths. This trend was further corroborated by the results obtained for A. rostratus at 1500 m depth. Hence, the present findings suggest the, at least temporary, existence of a pollution gradient between Blanes canyon and the open slope at shallower depths and this resulted in alterations of the physiology of deep-sea organisms dwelling within this area.

Soil Moisture, Coastline Curvature, and Sea Breeze Initiated Precipitation Over Florida

NASA Technical Reports Server (NTRS)

Baker, R. David; Lynn, Barry H.; Boone, Aaron; Tao, Wei-Kuo

1999-01-01

Land surface-atmosphere interaction plays a key role in the development of summertime convection and precipitation over the Florida peninsula. Land-ocean temperature contrasts induce sea-breeze circulations along both coasts. Clouds develop along sea-breeze fronts, and significant precipitation can occur during the summer months. However, other factors such as soil moisture distribution and coastline curvature may modulate the timing, location, and intensity of sea breeze initiated precipitation. Here, we investigate the role of soil moisture and coastline curvature on Florida precipitation using the 3-D Goddard Cumulus Ensemble (GCE) cloud model coupled with the Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) land surface model. This study utilizes data from the Convection and Precipitation Electrification Experiment (CaPE) collected on 27 July 1991. Our numerical simulations suggest that a realistic distribution of soil moisture influences the location and intensity of precipitation but not the timing of precipitation. In contrast, coastline curvature affects the timing and location of precipitation but has little influence on peak rainfall rates. However, both factors (soil moisture and coastline curvature) are required to fully account for observed rainfall amounts.

NOAA Photo Library - America's Coastlines

Science.gov Websites

coastline and the adjacent coastal regions. NOAA and its predecessor agencies have been observing, studying 19th century church Historical Coastal Views Publication of the National Oceanic & Atmospheric

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of changing field boundaries. When field boundaries are changed to include areas of land that were... Section 12.22 Agriculture Office of the Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Highly Erodible Land Conservation § 12.22 Highly erodible field determination criteria. (a...

Seasonal variations in erodibility and sediment transport potential in a mesotidal channel-flat complex, Willapa Bay, WA

NASA Astrophysics Data System (ADS)

Wiberg, Patricia L.; Law, Brent A.; Wheatcroft, Robert A.; Milligan, Timothy G.; Hill, Paul S.

2013-06-01

Measurements of erodibility, porosity and sediment size were made three times over the course of a year at sites within a muddy, mesotidal flat-channel complex in southern Willapa Bay, WA, to examine spatial and seasonal variations in sediment properties and transport potential. Average critical shear stress profiles, the metric we used for erodibility, were quantified using a power-law fit to cumulative eroded mass vs. shear stress for the flats and channel. Laboratory erosion measurements of deposits made from slurries of flat and channel sediment were used to quantify erodibility over consolidation time scales ranging from 6 to 96h. Erodibility of the tidal flats was consistently low, with spatial variability comparable to seasonal variability despite seasonal changes in biological activity. In contrast, channel-bed erodibility underwent large seasonal variations, with mobile sediment present in the channel thalweg during winter that was absent in the spring and summer, when channel-bed erodibility was low and comparable to that of the tidal flats. Sediment on the northern (left) channel flank was mobile in summer and winter, whereas sediment on the southern flank was not. Seasonal changes in channel-bed erodibility are sufficient to produce order-of-magnitude changes in suspended sediment concentrations during peak tidal flows. Porosity just below the sediment surface was the best predictor of erodibility in our study area.

Our Dynamic Coastline.

ERIC Educational Resources Information Center

Aubrey, David G.

1980-01-01

Discusses mechanisms which influence both rapid and gradual modifications of ocean beaches. Among factors described are storms, waves, currents, tides, sediment transport, and climate. Some effects of these forces upon coastline configurations are also presented. (WB)

Soil quality changes after topsoil addition to eroded land

USDA-ARS?s Scientific Manuscript database

Soil-landscape rehabilitation within eroded fields can be accomplished by moving topsoil from depositional to eroded landscape positions. The purpose is to improve soil quality and productivity of the upper root zone in eroded areas of the field. Changes in soil quality may be estimated through chan...

Geomorphology, acoustic backscatter, and processes in Santa Monica Bay from multibeam mapping.

PubMed

Gardner, James V; Dartnell, Peter; Mayer, Larry A; Hughes Clarke, John E

2003-01-01

Santa Monica Bay was mapped in 1996 using a high-resolution multibeam system, providing the first substantial update of the submarine geomorphology since the initial compilation by Shepard and Emery [(1941) Geol. Soc. Amer. Spec. Paper 31]. The multibeam mapping generated not only high-resolution bathymetry, but also coregistered, calibrated acoustic backscatter at 95 kHz. The geomorphology has been subdivided into six provinces; shelf, marginal plateau, submarine canyon, basin slope, apron, and basin. The dimensions, gradients, and backscatter characteristics of each province is described and related to a combination of tectonics, climate, sea level, and sediment supply. Fluctuations of eustatic sea level have had a profound effect on the area; by periodically eroding the surface of Santa Monica plateau, extending the mouth of the Los Angeles River to various locations along the shelf break, and by connecting submarine canyons to rivers. A wetter glacial climate undoubtedly generated more sediment to the rivers that then transported the increased sediment load to the low-stand coastline and canyon heads. The trends of Santa Monica Canyon and several bathymetric highs suggest a complex tectonic stress field that has controlled the various segments. There is no geomorphic evidence to suggest Redondo Canyon is fault controlled. The San Pedro fault can be extended more than 30 km to the northwest by the alignment of a series of bathymetric highs and abrupt changes in direction of channel thalwegs.

Manure effects on soil N in eroded and non-eroded, sprinkler-irrigated soil

USDA-ARS?s Scientific Manuscript database

Manure effects on nitrate-N transport through irrigated, low-organic matter calcareous soil are not well known. This field study quantified the effects of a one-time fall application of stockpiled dairy manure and urea on in-season and over-winter nitrate-N transport through non-eroded and eroded (...

Bond strength and interfacial morphology of orthodontic brackets bonded to eroded enamel treated with calcium silicate-sodium phosphate salts or resin infiltration.

PubMed

Costenoble, Aline; Vennat, Elsa; Attal, Jean-Pierre; Dursun, Elisabeth

2016-11-01

 To investigate the shear bond strength (SBS) of orthodontic brackets bonded to eroded enamel treated with preventive approaches and to examine the enamel/bracket interfaces.  Ninety-one brackets were bonded to seven groups of enamel samples: sound; eroded; eroded+treated with calcium silicate-sodium phosphate salts (CSP); eroded+infiltrated by ICON ® ; eroded+infiltrated by ICON ® and brackets bonded with 1-month delay; eroded+infiltrated by an experimental resin; and eroded+infiltrated by an experimental resin and brackets bonded with 1-month delay. For each group, 12 samples were tested in SBS and bond failure was assessed with the adhesive remnant index (ARI); one sample was examined using scanning electron microscopy (SEM).  Samples treated with CSP or infiltration showed no significant differences in SBS values with sound samples. Infiltrated samples followed by a delayed bonding showed lower SBS values. All of the values remained acceptable. The ARI scores were significantly higher for sound enamel, eroded, and treated with CSP groups than for all infiltrated samples. SEM examinations corroborated the findings.  Using CSP or resin infiltration before orthodontic bonding does not jeopardize the bonding quality. The orthodontic bonding should be performed shortly after the resin infiltration.

Aggregate Stability and Erodibility of Purple Soil on Sloping Farmland as affected by different Soil Thickness

NASA Astrophysics Data System (ADS)

Huang, Xinjun; Zhang, Qingwen; Chen, Shanghong; Dong, Yuequn; Xiao, Meijia; Hamed, Lamy Mamdoh Mohamed

2017-04-01

Soil thickness is basic limiting condition for purple soil, not only due to its effect on crop production, but also its effect on soil structure. Steady-state of soil thickness will be achieved over time, as result the soil aggregate which the key factor of soil erodibility can be enhanced as well. However, the effect of soil thickness on aggregates stability and the characteristics of soil erodibility in sloping land have not yet fully understood.A field survey was conducted in hilly area of Sichuan region located in southeast China to study the relationship between soil aggregate stability and soil erodibility on sloping farmland under different four thickness (100cm, 80cm, 60cm, 30cm) of purple soil. Based on two different sieving methods (Dry and Wet sieving), we analyzed soil aggregate stability and its effect on soil erodibility within depth of 0-30cm soil layers. The results indicated that: Water stable aggregate on sloping farmland was ranged between 37.9% to 58.6%, where it increased with increasing the soil thickness. Moreover, fractal dimension calculated from dry-sieving and wet-sieving was 2.06-2.49 and 2.70-2.85 respectively, where it decreased with decreasing the soil thickness. The overall soil erodibility was 0.05-1.00 and a negative significant correlation was found between soil aggregate stability and erodibility(P<0.01). Moreover, farmland with thick soil profile tended to be high in soil erodibility within the top soil layer (0-30cm). The results reveal that soil thickness can affect soil aggregate stability as well as erodibility. As soil thickness increased, the top soil became more stable and less erodible. Keywords：purple soil; soil thickness; soil aggregate；soil erodibility

Comparing wave shoaling methods used in large-scale coastal evolution modeling

NASA Astrophysics Data System (ADS)

Limber, P. W.; Adams, P. N.; Murray, A.

2013-12-01

A variety of methods are available to simulate wave propagation from the deep ocean to the surf zone. They range from simple and computationally fast (e.g. linear wave theory applied to shore-parallel bathymetric contours) to complicated and computationally intense (e.g., Delft's ';Simulating WAves Nearshore', or SWAN, model applied to complex bathymetry). Despite their differences, the goal of each method is the same with respect to coastline evolution modeling: to link offshore waves with rates of (and gradients in) alongshore sediment transport. Choosing a shoaling technique for modeling coastline evolution should be partly informed by the spatial and temporal scales of the model, as well as the model's intent (is it simulating a specific coastline, or exploring generic coastline dynamics?). However, the particular advantages and disadvantages of each technique, and how the advantages/disadvantages vary over different model spatial and temporal scales, are not always clear. We present a wave shoaling model that simultaneously computes breaking wave heights and angles using three increasingly complex wave shoaling routines: the most basic approach assuming shore-parallel bathymetric contours, a wave ray tracing method that includes wave energy convergence and divergence and non-shore-parallel contours, and a spectral wave model (SWAN). Initial results show reasonable agreement between wave models along a flat shoreline for small (1 m) wave heights, low wave angles (0 to 10 degrees), and simple bathymetry. But, as wave heights and angles increase, bathymetry becomes more variable, and the shoreline shape becomes sinuous, the model results begin to diverge. This causes different gradients in alongshore sediment transport between model runs employing different shoaling techniques and, therefore, different coastline behavior. Because SWAN does not approximate wave breaking (which drives alongshore sediment transport) we use a routine to extract grid cells from SWAN output where wave height is approximately one-half of the water depth (a standard wave breaking threshold). The goal of this modeling exercise is to understand under what conditions a simple wave model is sufficient for simulating coastline evolution, and when using a more complex shoaling routine can optimize a coastline model. The Coastline Evolution Model (CEM; Ashton and Murray, 2006) is used to show how different shoaling routines affect modeled coastline behavior. The CEM currently includes the most basic wave shoaling approach to simulate cape and spit formation. We will instead couple it to SWAN, using the insight from the comprehensive wave model (above) to guide its application. This will allow waves transformed over complex bathymetry, such as cape-associated shoals and ridges, to be input for the CEM so that large-scale coastline behavior can be addressed in less idealized environments. Ashton, A., and Murray, A.B., 2006, High-angle wave instability and emergent shoreline shapes: 1. Modeling of sand waves, flying spits, and capes: Journal of Geophysical Research, v. 111, p. F04011, doi:10.1029/2005JF000422.

Remote Sensing Application of the Geophysical Changes in the Coastlines and Rivers of Zambales, Philippines

NASA Astrophysics Data System (ADS)

Paz-Alberto, Annie Melinda; Sison, Melissa Joy M.; Bulaong, Edmark Pablo; Pakaigue, Marietta A.

2016-06-01

Geophysical changes in river outlet, river upstream and coastlines near the rivers of Bucao and Santo Tomas in Zambales, Philippines were analyzed using the Google Earth's historical satellite imageries from 2004 to 2013. Data in 2015 were gathered from in situ field measurements ground validation. The study aimed to measure and determine changes in the width of river outlet, width of river bank upstream and shifting of coastline. Results revealed that there was a decrease and increase in the width size of the Bucao and Santo Tomas river outlets, respectively during the study period. Geophysical changes occurred in the two rivers due to the continuous supply of lahar as an after effect of the Mount Pinatubo eruption in 1991. Coastline positions near the two rivers also changed. The highest rate of erosion along the coastal area was prevalently observed near the river outlet of both rivers. Moreover, accretion was observed in the coastline of Santo Tomas and erosion phenomenon was observed in the North and South coastlines of Bucao River. The shifting was caused by natural processes such as erosion, sedimentation and natural calamities as well as anthropogenic processes such as reclamation/quarrying. Occurrence of erosion and sedimentation played active roles in the changes of coastlines during the study period. Furthermore, the upstream of the Bucao river changed physically due to deposits of lahar present in the upstream which are being discharged directly and continuously going down to the river. Generally, the width of the Bucao River upstream decreased its size because of the accumulated sediment in the riverbank. On the other hand, the observed erosion is caused by high velocity of river during heavy rains and typhoons. The width of the Santo Tomas river bank upstream did not change due to the construction of concrete dikes which prevent the lahar-filled river from breaching the embankment and flooding the agricultural, residential and commercial areas near the river.

Modeling changes in rill erodibility and critical shear stress on native surface roads

Treesearch

Randy B. Foltz; Hakjun Rhee; William J. Elliot

2008-01-01

This study investigated the effect of cumulative overland flow on rill erodibility and critical shear stress on native surface roads in central Idaho. Rill erodibility decreased exponentially with increasing cumulative overland flow depth; however, critical shear stress did not change. The study demonstrated that road erodibility on the studied road changes over the...

Method to characterize directional changes in Arctic sea ice drift and associated deformation due to synoptic atmospheric variations using Lagrangian dispersion statistics

NASA Astrophysics Data System (ADS)

Lukovich, Jennifer V.; Geiger, Cathleen A.; Barber, David G.

2017-07-01

A framework is developed to assess the directional changes in sea ice drift paths and associated deformation processes in response to atmospheric forcing. The framework is based on Lagrangian statistical analyses leveraging particle dispersion theory which tells us whether ice drift is in a subdiffusive, diffusive, ballistic, or superdiffusive dynamical regime using single-particle (absolute) dispersion statistics. In terms of sea ice deformation, the framework uses two- and three-particle dispersion to characterize along- and across-shear transport as well as differential kinematic parameters. The approach is tested with GPS beacons deployed in triplets on sea ice in the southern Beaufort Sea at varying distances from the coastline in fall of 2009 with eight individual events characterized. One transition in particular follows the sea level pressure (SLP) high on 8 October in 2009 while the sea ice drift was in a superdiffusive dynamic regime. In this case, the dispersion scaling exponent (which is a slope between single-particle absolute dispersion of sea ice drift and elapsed time) changed from superdiffusive (α ˜ 3) to ballistic (α ˜ 2) as the SLP was rounding its maximum pressure value. Following this shift between regimes, there was a loss in synchronicity between sea ice drift and atmospheric motion patterns. While this is only one case study, the outcomes suggest similar studies be conducted on more buoy arrays to test momentum transfer linkages between storms and sea ice responses as a function of dispersion regime states using scaling exponents. The tools and framework developed in this study provide a unique characterization technique to evaluate these states with respect to sea ice processes in general. Application of these techniques can aid ice hazard assessments and weather forecasting in support of marine transportation and indigenous use of near-shore Arctic areas.

Diagnosis of osteoporosis in rural Arctic Greenland: a clinical case using plain chest radiography for secondary prevention and consideration of tools for primary prevention in remote areas.

PubMed

Fleischer, Inuuteq; Schæbel, Louise K; Albertsen, Nadja; Sørensen, Vibeke N; Andersen, Stig

2017-01-01

Osteoporosis is a frequent disease in many populations. The hallmark is fragility fractures, which are harbingers of future fractures, disability, mortality and cost on society. The occurrence increases with age, low vitamin D level and smoking. Smoking rates are high, vitamin D is low and life expectancy is rising steeply in Greenland, as is the need for focus on osteoporosis. We report a case that uses a simple and readily available tool to diagnose osteoporosis at the hospital in Sisimiut, a town of 5000 inhabitants on the west coast of Greenland. A 51-year-old Inuit woman was seen due to lower back pain. No trauma could be recalled. Laboratory results showed a low vitamin D level and normal S-calcium, S-phosphate, S-parathyroid hormone, S-thyrotropin, erythrocyte sedimentation rate, S-creatinine and hemoglobin. The lateral chest radiograph demonstrated a reduction of anterior height of the seventh and ninth thoracic vertebral bodies of 50% and 40% respectively. Chest radiographs are frequently done in the towns along the vast coastline of Greenland, the world's largest island. They are transferred to the hospital in the capital city Nuuk using existing tele-technology, and specialist evaluations are given in electronic records available at the coastal hospitals. Effective therapies for osteoporosis are available and the identification of vertebral fractures that merit treatment may prevent future fractures, morbidity and mortality. Fragility fractures are frequent in old age and the steep rise in life expectancy and in the number of old people in Greenland emphasize the need for a focus on management of osteoporosis. Geography provides a diagnostic challenge to rural and remote areas that can be overcome by the use of lateral chest radiographs as it relies on facilities readily available. Clinical risk assessment tools with high specificity may support further osteoporosis risk prediction in remote Arctic societies.

Computational efficient unsupervised coastline detection from single-polarization 1-look SAR images of complex coastal environments

NASA Astrophysics Data System (ADS)

Garzelli, Andrea; Zoppetti, Claudia; Pinelli, Gianpaolo

2017-10-01

Coastline detection in synthetic aperture radar (SAR) images is crucial in many application fields, from coastal erosion monitoring to navigation, from damage assessment to security planning for port facilities. The backscattering difference between land and sea is not always documented in SAR imagery, due to the severe speckle noise, especially in 1-look data with high spatial resolution, high sea state, or complex coastal environments. This paper presents an unsupervised, computationally efficient solution to extract the coastline acquired by only one single-polarization 1-look SAR image. Extensive tests on Spotlight COSMO-SkyMed images of complex coastal environments and objective assessment demonstrate the validity of the proposed procedure which is compared to state-of-the-art methods through visual results and with an objective evaluation of the distance between the detected and the true coastline provided by regional authorities.

Coastline change and marine geo-hazards in the Yellow River Delta (China)

NASA Astrophysics Data System (ADS)

Zhou, L.; Liu, J.; Liu, X.

2003-04-01

COASTLINE CHANGE AND MARINE GEO-HAZARDS IN THE YELLOW RIVER DELTA (CHINA) Zhou Liangyong(1,2), Liu Jian(1,3), Liu Xiqing(1) (1)Qingdao Institute of Marine Geology,(2)Ocean University of China,(3)Research Centre for Coastal Geology, CGS qdzliangyong@cgs.gov.cn/Fax: +86-532-5720553 Satellite remote sensing, bathymetry and high-resolution seismic data have been used to examine the coastline change during the period from 1976 to 2001 and the offshore marine geo-hazards in the modern Yellow River Delta. Trends in the temporal sequence of the eight coastlines derived from Landsat images were used in the definition of erosional classes of the coastline. Four classes were distinguished, including rapid erosion (>100 m/yr), moderate erosion (20-100 m/yr), no detectable erosion (-1 - 20 m/yr), and accretion (-200--1 m/yr). We revealed the subtle variations in sea floor morphology and sediment geometries using high-resolution acoustic survey. Many kinds of geo-hazards were identified in the active subaqueous delta lobe and abandoned delta lobes, such as seabed erosions, gas-charged sediments, listric faults, synsedimentary rises, incised palaeo-valleys, infilled gullies, diapirs, active slope failures and sediment collapses. The resultant map of geo-envrionment and geo-hazards presents the coastline change and distribution of geo-hazards mentioned above in the Yellow River Delta. The gas-charged sediment distributes mainly in the abandoned delta lobes. The synsedimentary rise outside of the modern river mouth is a new evidence for the seabed mass-movement which modifies the progradational subaquaeous slopes of modern Yellow River Delta.

30 CFR 219.416 - How will the qualified OCS revenues be allocated to coastal political subdivisions within the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... each coastal political subdivision's population bears to the population of all coastal political... political subdivision's miles of coastline bears to the number of miles of coastline of all coastal...

30 CFR 519.416 - How will the qualified OCS revenues be allocated to coastal political subdivisions within the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... each coastal political subdivision's population bears to the population of all coastal political... political subdivision's miles of coastline bears to the number of miles of coastline of all coastal...

30 CFR 519.416 - How will the qualified OCS revenues be allocated to coastal political subdivisions within the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... each coastal political subdivision's population bears to the population of all coastal political... political subdivision's miles of coastline bears to the number of miles of coastline of all coastal...

30 CFR 519.416 - How will the qualified OCS revenues be allocated to coastal political subdivisions within the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... each coastal political subdivision's population bears to the population of all coastal political... political subdivision's miles of coastline bears to the number of miles of coastline of all coastal...

Erodibility of selected soils and estimates of sediment yields in the San Juan Basin, New Mexico

USGS Publications Warehouse

Summer, Rebecca M.

1981-01-01

Onsite rainfall-simulation experiments were conducted to derive field-erodibility indexes for rangeland soils and soils disturbed by mining in coal fields of northwestern New Mexico. Mean indexes on rangeland soils range from 0 grams (of detached soil) on dune soil to 121 grams on wash-transport zones. Mean field-erodibility-index values of soils disturbed by mining range from 16 to 32 grams; they can be extrapolted to nearby coal fields where future mining is expected. Because field-erodibility-index data allow differentiation of erodibilities across a variable landscape, these indexes were used to adjust values of K, the erodibility factor of the Universal Soil Loss Equation. Estimates of soil loss and sediment yield were then calculated for a small basin following mining. (USGS)

The coastal ocean response to the global warming acceleration and hiatus

PubMed Central

Liao, Enhui; Lu, Wenfang; Yan, Xiao-Hai; Jiang, Yuwu; Kidwell, Autumn

2015-01-01

Coastlines are fundamental to humans for habitation, commerce, and natural resources. Many coastal ecosystem disasters, caused by extreme sea surface temperature (SST), were reported when the global climate shifted from global warming to global surface warming hiatus after 1998. The task of understanding the coastal SST variations within the global context is an urgent matter. Our study on the global coastal SST from 1982 to 2013 revealed a significant cooling trend in the low and mid latitudes (31.4% of the global coastlines) after 1998, while 17.9% of the global coastlines changed from a cooling trend to a warming trend concurrently. The trend reversals in the Northern Pacific and Atlantic coincided with the phase shift of Pacific Decadal Oscillation and North Atlantic Oscillation, respectively. These coastal SST changes are larger than the changes of the global mean and open ocean, resulting in a fast increase of extremely hot/cold days, and thus extremely hot/cold events. Meanwhile, a continuous increase of SST was detected for a considerable portion of coastlines (46.7%) with a strengthened warming along the coastlines in the high northern latitudes. This suggests the warming still continued and strengthened in some regions after 1998, but with a weaker pattern in the low and mid latitudes. PMID:26568024

The coastal ocean response to the global warming acceleration and hiatus.

PubMed

Liao, Enhui; Lu, Wenfang; Yan, Xiao-Hai; Jiang, Yuwu; Kidwell, Autumn

2015-11-16

Coastlines are fundamental to humans for habitation, commerce, and natural resources. Many coastal ecosystem disasters, caused by extreme sea surface temperature (SST), were reported when the global climate shifted from global warming to global surface warming hiatus after 1998. The task of understanding the coastal SST variations within the global context is an urgent matter. Our study on the global coastal SST from 1982 to 2013 revealed a significant cooling trend in the low and mid latitudes (31.4% of the global coastlines) after 1998, while 17.9% of the global coastlines changed from a cooling trend to a warming trend concurrently. The trend reversals in the Northern Pacific and Atlantic coincided with the phase shift of Pacific Decadal Oscillation and North Atlantic Oscillation, respectively. These coastal SST changes are larger than the changes of the global mean and open ocean, resulting in a fast increase of extremely hot/cold days, and thus extremely hot/cold events. Meanwhile, a continuous increase of SST was detected for a considerable portion of coastlines (46.7%) with a strengthened warming along the coastlines in the high northern latitudes. This suggests the warming still continued and strengthened in some regions after 1998, but with a weaker pattern in the low and mid latitudes.

Modelling the morphodynamics and co-evolution of coast and estuarine environments

NASA Astrophysics Data System (ADS)

Morris, Chloe; Coulthard, Tom; Parsons, Daniel R.; Manson, Susan; Barkwith, Andrew

2017-04-01

The morphodynamics of coast and estuarine environments are known to be sensitive to environmental change and sea-level rise. However, whilst these systems have received considerable individual research attention, how they interact and co-evolve is relatively understudied. These systems are intrinsically linked and it is therefore advantageous to study them holistically in order to build a more comprehensive understanding of their behaviour and to inform sustainable management over the long term. Complex environments such as these are often studied using numerical modelling techniques. Inherent from the limited research in this area, existing models are currently not capable of simulating dynamic coast-estuarine interactions. A new model is being developed through coupling the one-line Coastline Evolution Model (CEM) with CAESAR-Lisflood (C-L), a hydrodynamic Landscape Evolution Model. It is intended that the eventual model be used to advance the understanding of these systems and how they may evolve over the mid to long term in response to climate change. In the UK, the Holderness Coast, Humber Estuary and Spurn Point system offers a diverse and complex case study for this research. Holderness is one of the fastest eroding coastlines in Europe and research suggests that the large volumes of material removed from its cliffs are responsible for the formation of the Spurn Point feature and for the Holocene infilling of the Humber Estuary. Marine, fluvial and coastal processes are continually reshaping this system and over the next century, it is predicted that climate change could lead to increased erosion along the coast and supply of material to the Humber Estuary and Spurn Point. How this manifests will be hugely influential to the future morphology of these systems and the existence of Spurn Point. Progress to date includes a new version of the CEM that has been prepared for integration into C-L and includes an improved graphical user interface and more complex geomorphological processes. Preliminary results from simulations of the Holderness Coast and Spurn Point support findings of other authors, who suggest that changes to the wave climate influences sediment transport patterns in the nearshore zone. The angle of wave approach to the Holderness shows particular significance compared to the height of waves, with an optimum volume of material transported at 42 degrees. Further applications and results of this new model will be presented and discussed.

Experimental Study of Factors Affecting Soil Erodibility

NASA Astrophysics Data System (ADS)

Larionov, G. A.; Bushueva, O. G.; Gorobets, A. V.; Dobrovolskaya, N. G.; Kiryukhina, Z. P.; Krasnov, S. F.; Litvin, L. F.; Maksimova, I. A.; Sudnitsyn, I. I.

2018-03-01

The effect of different factors and preparation conditions of monofraction samples from the arable horizon of leached chernozem on soil erodibility and its relationship with soil tensile strength (STS) has been studied. The exposure of samples at 38°C reduces their erodibility by two orders of magnitude. The drying of samples, on the contrary, increases their erodibility. It has been shown that erodibility decreases during the experiment. It has been found that the inoculation of soil with yeast cultures ( Naganishia albida, Lipomyces tetrasporus) reliably increases the STS value in 1.5-1.9 times. The sterile soil is eroded more intensively than the unsterile soil: at 4.9 and 0.3 g/(m2 s), respectively. The drying of soil followed by wetting to the initial water content (30%) has no significant effect on the STS value in almost all experimental treatments.

Investigating the effect of storm events on the particle size distribution in a combined sewer simulator.

PubMed

Biggs, C A; Prall, C; Tait, S; Ashley, R

2005-01-01

The changes in particle size of sewer sediment particles rapidly eroded from a previously deposited sediment bed are described, using a rotating annular flume as a laboratory scale sewer simulator. This is the first time that particle size distributions of eroded sewer sediments from a previously deposited sediment bed have been monitored in such a controlled experimental environment. Sediments from Loenen, The Netherlands and Dundee, UK were used to form deposits in the base of the annular flume (WL Delft Netherlands) with varying conditions for consolidation in order to investigate the effect of changing consolidation time, temperature and sediment type on the amount and size of particles eroded from a bed under conditions of increasing shear. The median size of the eroded particles did not change significantly with temperature, although the eroded suspended solids concentration was greater for the higher temperature under the same shear stresses, indicating a weaker bed deposit. An increase in consolidation time caused an increase in median size of eroded solids at higher bed shear stresses, and this was accompanied by higher suspended solids concentrations. As the shear stress increased, the solids eroded from the bed developed under a longer consolidation time (56 hours) tended towards a broad unimodal distribution, whilst the size distribution of solids eroded from beds developed under shorter consolidation times (18 or 42 hours) retained a bi- or tri-modal distribution. Using different types of sediment in the flume had a marked effect on the size of particles eroded.

Threats to coastal communities of Mahanadi delta due to imminent consequences of erosion - Present and near future.

PubMed

Mukhopadhyay, Anirban; Ghosh, Pramit; Chanda, Abhra; Ghosh, Amit; Ghosh, Subhajit; Das, Shouvik; Ghosh, Tuhin; Hazra, Sugata

2018-05-11

Coastal erosion is a natural hazard which causes significant loss to properties as well as coastal habitats. Coastal districts of Mahanadi delta, one of the most populated deltas of the Indian subcontinent, are suffering from the ill effects of coastal erosion. An important amount of assets is being lost every year along with forced migration of huge portions of coastal communities due to erosion. An attempt has been made in this study to predict the future coastline of the Mahanadi Delta based on historical trends. Historical coastlines of the delta have been extracted using semi-automated Tasselled Cap technique from the LANDSAT satellite imageries of the year 1990, 1995, 2000, 2006 and 2010. Using Digital Shoreline Assessment System (DSAS) tool of USGS, the trend of the coastline has been assessed in the form of End Point Rate (EPR) and Linear Regression Rate (LRR). A hybrid methodology has been adopted using statistical (EPR) and trigonometric functions to predict the future positions of the coastlines of the years 2020, 2035 and 2050. The result showed that most of the coastline (≈65%) is facing erosion at present. The predicted outcome shows that by the end of year 2050 the erosion scenario will worsen which in turn would lead to very high erosion risk for 30% of the total coastal mouzas (small administrative blocks). This study revealed the coastal erosion trend of Mahanadi delta and based on the predicted coastlines it can be inferred that the coastal communities in near future would be facing substantial threat due to erosion particularly in areas surrounding Puri (a renowned tourist pilgrimage) and Paradwip (one of the busiest ports and harbours of the country). Copyright © 2018 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Obu, Jaroslav; Lantuit, Hugues; Grosse, Guido; Günther, Frank; Sachs, Torsten; Helm, Veit; Fritz, Michael

2017-09-01

Erosion of permafrost coasts has received increasing scientific attention since 1990s because of rapid land loss and the mobilisation potential of old organic carbon. The majority of permafrost coastal erosion studies are limited to time periods from a few years to decades. Most of these studies emphasize the spatial variability of coastal erosion, but the intensity of inter-annual variations, including intermediate coastal aggradation, remains poorly documented. We used repeat airborne Light Detection And Ranging (LiDAR) elevation data from 2012 and 2013 with 1 m horizontal resolution to study coastal erosion and accompanying mass-wasting processes in the hinterland. Study sites were selected to include different morphologies along the coast of the Yukon Coastal Plain and on Herschel Island. We studied elevation and volume changes and coastline movement and compared the results between geomorphic units. Results showed simple uniform coastal erosion from low coasts (up to 10 m height) and a highly diverse erosion pattern along coasts with higher backshore elevation. This variability was particularly pronounced in the case of active retrogressive thaw slumps, which can decrease coastal erosion or even cause temporary progradation by sediment release. Most of the extremes were recorded in study sites with active slumping (e.g. 22 m of coastline retreat and 42 m of coastline progradation). Coastline progradation also resulted from the accumulation of slope collapse material. These occasional events can significantly affect the coastline position on a specific date and can affect coastal retreat rates as estimated in long term by coastline digitalisation from air photos and satellite imagery. These deficiencies can be overcome by short-term airborne LiDAR measurements, which provide detailed and high-resolution information about quickly changing elevations in coastal areas.

Hepatic CYP1A levels and EROD activity in English sole: biomonitoring of marine contaminants in Vancouver Harbour.

PubMed

Miller, K A; Addison, R F; Bandiera, S M

2004-01-01

To assess chemical contaminant stress in the marine environment, ethoxyresorufin-O-deethylase (EROD) activity and cytochrome P450 1A (CYP1A) expression were measured in 88 English Sole (Pleuronectes vetulus) collected during May and June 1999 from four sites in Vancouver Harbour and at an expected reference site outside the harbour. Hepatic microsomes were prepared from the fish and analyzed for total CYP content, EROD activity, and CYP1A protein levels. Hepatic EROD activity and CYP1A protein levels were elevated in fish from two sites in the inner harbour. A comparison with sediment chemistry data showed that fish with increased EROD activity and CYP1A levels came from sites containing relatively high levels of polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Unexpectedly high levels of EROD activity and CYP1A protein were also found in fish from a reference site near Gibsons, in Howe Sound. The elevated EROD activity and CYP1A expression in fish from this site cannot be explained by the chemical analysis data collected.

Landfast Sea Ice Breakouts: Stabilizing Ice Features, Oceanic and Atmospheric Forcing at Barrow, Alaska

NASA Astrophysics Data System (ADS)

Jones, J.; Eicken, H.; Mahoney, A. R.; MV, R.; Kambhamettu, C.; Fukamachi, Y.; Ohshima, K. I.; George, C.

2016-12-01

Landfast sea ice is an important seasonal feature along most Arctic coastlines, such as that of the Chukchi Sea near Barrow, Alaska. Its stability throughout the ice season is determined by many factors but grounded pressure ridges are the primary stabilizing component. Landfast ice breakouts occur when these grounded ridges fail or unground, and previously stationary ice detaches from the coast and drifts away. Using ground-based radar imagery from a coastal ice and ocean observatory at Barrow, we have developed a method to estimate the extent of grounded ridges by tracking ice motion and deformation over the course of winter and have derived ice keel depth and potential for grounding from cumulative convergent ice motion. Estimates of landfast ice grounding strength have been compared to the atmospheric and oceanic stresses acting on the landfast ice before and during breakout events to determine prevailing causes for the failure of stabilizing features. Applying this approach to two case studies in 2008 and 2010, we conclude that a combination of atmospheric and oceanic stresses may have caused the breakouts analyzed in this study, with the latter as the dominant force. Preconditioning (as weakening) of grounded ridges by sea level variations may facilitate failure of the ice sheet leading to breakout events.

Landfast sea ice breakouts: Stabilizing ice features, oceanic and atmospheric forcing at Barrow, Alaska

NASA Astrophysics Data System (ADS)

Jones, Joshua; Eicken, Hajo; Mahoney, Andrew; MV, Rohith; Kambhamettu, Chandra; Fukamachi, Yasushi; Ohshima, Kay I.; George, J. Craig

2016-09-01

Landfast sea ice is an important seasonal feature along most Arctic coastlines, such as that of the Chukchi Sea near Barrow, Alaska. Its stability throughout the ice season is determined by many factors but grounded pressure ridges are the primary stabilizing component. Landfast ice breakouts occur when these grounded ridges fail or unground, and previously stationary ice detaches from the coast and drifts away. Using ground-based radar imagery from a coastal ice and ocean observatory at Barrow, we have developed a method to estimate the extent of grounded ridges by tracking ice motion and deformation over the course of winter and have derived ice keel depth and potential for grounding from cumulative convergent ice motion. Estimates of landfast ice grounding strength have been compared to the atmospheric and oceanic stresses acting on the landfast ice before and during breakout events to determine prevailing causes for the failure of stabilizing features. Applying this approach to two case studies in 2008 and 2010, we conclude that a combination of atmospheric and oceanic stresses may have caused the breakouts analyzed in this study, with the latter as the dominant force. Preconditioning (as weakening) of grounded ridges by sea level variations may facilitate failure of the ice sheet leading to breakout events.

Remotely Sensing Lake Water Volumes on the Inner Arctic Coastal Plain of Northern Alaska

NASA Astrophysics Data System (ADS)

Simpson, C. E.; Arp, C. D.; Jones, B. M.; Hinkel, K. M.; Carroll, M.; Smith, L. C.

2017-12-01

Thermokarst lake depth is controlled by the amount of excess ice in near-surface permafrost, with lake depths of about 1 - 3 m in areas of epigenetic permafrost and over 10 m in areas of syngenetic permafrost. An important exception to these general patterns is found on the inner Arctic Coastal Plain (ACP) of northern Alaska, where deep lakes occur in Pleistocene-aged, ground-ice poor sandy terrain. These lakes cover 20% of the currently inactive sand sheet and dune deposit (referred to as the Pleistocene Sand Sea) that comprises approximately 7000 km2 of the ACP. Surrounded by high and eroding bluffs, sand sea lakes lie in natural depressions and are characterized by wide, shallow littoral shelves and central troughs that are typically oriented NNW to SSE and can reach depths greater than 20 m. Despite their unique form and extensive coverage, these lakes have received little prior study and a literature gap remains regarding regional water storage. This research classifies sand sea lakes, estimates individual lake volume, and provides a first quantification of water storage in a region of the lake-dominated ACP. We measured bathymetric profiles in 19 sand sea lakes using a sonar recorder to capture various lake depth gradients. Bathymetric surveys collected by oil industry consultants, lake monitoring programs, and habitat studies serve as additional datasets. These field measured lake depth data points were used to classify Color Infrared Photography, WorldView-2 satellite imagery, and Landsat-OLI satellite imagery to develop a spectral depth-classification algorithm and facilitate the interpolation of the bathymetry for study lakes in the inner ACP. Finally, we integrate the remotely sensed bathymetry and imagery-derived lake surface area to estimate individual and regional-scale lake volume. In addition to the natural function of these lakes in water storage, energy balance, and habitat provision, the need for winter water supply to build ice roads for oil exploration and development makes lakes in this region an increasingly valuable resource and knowledge of their storage essential. Estimating regional and lake-by-lake water volume will facilitate better management of expanding development activities and serve as a baseline by which to evaluate future responses to ongoing climate change in the Arctic.

Regional approach to modeling the transport of floating plastic debris in the Adriatic Sea.

PubMed

Liubartseva, S; Coppini, G; Lecci, R; Creti, S

2016-02-15

Sea surface concentrations of plastics and their fluxes onto coastlines are simulated over 2009-2015. Calculations incorporate combinations of terrestrial and maritime litter inputs, the Lagrangian model MEDSLIK-II forced by AFS ocean current simulations, and ECMWF wind analyses. With a relatively short particle half-life of 43.7 days, the Adriatic Sea is defined as a highly dissipative basin where the shoreline is, by construction, the main sink of floating debris. Our model results show that the coastline of the Po Delta receives a plastic flux of approximately 70 kg(km day)(-1). The most polluted sea surface area (>10 g km(-2) floating debris) is represented by an elongated band shifted to the Italian coastline and narrowed from northwest to southeast. Evident seasonality is found in the calculated plastic concentration fields and the coastline fluxes. Complex source-receptor relationships among the basin's subregions are quantified in impact matrices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Total petroleum hydrocarbons in sediments from the coastline and mangroves of the northern Persian Gulf.

PubMed

Mohebbi-Nozar, Seyedeh Laili; Zakaria, Mohamad Pauzi; Ismail, Wan Ruslan; Mortazawi, Mohammad Seddiq; Salimizadeh, Maryam; Momeni, Mohammad; Akbarzadeh, Gholamali

2015-06-15

To provide baseline information for the marine ecosystem of Hormozgan province, the distribution of petroleum hydrocarbons was evaluated in 52 stations involved in the mangrove and coastline ecosystem. Coastline sampling sites included areas facing harbor, river, domestic and industrial discharge. Sediment samples were analyzed based on ultraviolet fluorescence spectroscopy. Petroleum hydrocarbons showed narrow variations ranging from non-detectable (ND) to 1.71 and from 0.2 to 0.63μg/g dry weight for coastline and mangrove sediments, respectively. The detected concentrations for total petroleum hydrocarbons were lower than guideline values for ecological risk. Furthermore, the minimum environmental risk was confirmed by background levels for the Persian Gulf, the Sea of Oman, and detected values for reference areas. The results were regarded as background data in the studied area, and, considering the rapid expansion of activities related to the petroleum industry in Hormozgan province, the continuous monitoring of pollutants is recommended. Copyright © 2015 Elsevier Ltd. All rights reserved.

Coastal erosion in Sicily: geomorphologic impact and mitigation (Italy)

NASA Astrophysics Data System (ADS)

Liguori, V.; Manno, G.

2009-04-01

The coast of Sicily region stretches about 1400 km, bathing three different seas: the North tract, from Messina to Capo San Vito wash to the Tyrrhenian Sea, the oriental side, from Messina to Capo Passero, wash to the Ionian Sea, and finally the southern side wash to the Mediterranean. Of these, 395 km are made up of beaches and 970 km from rocky shores. The coastal morph-type were analyzed in relation to their evolutionary trend (backspace or advancement of the seaside), can be summarized as follows: a low shores of torrent plain (Messina), low shores with salt (Trapani), low shores beaches edged with dunal systems, subject to backspace, where urbanization has reduced or eliminated the internal sand dunes, shores on marine terraces, with beaches at the foot (Agrigento) and high shores non-affected of real phenomena of backspace, but subject to often dangerous events of detachment and collapse of blocks (high rocky shores). The marine and coastal environment is a complex and articulated, in balance with the Earth's environment, in which live together, but through different dynamics strongly interacting, ecosystems and marine ecosystems typically transition. The increasing density of population concentrated along the shores, the gradual expansion of activities related to the use of marine and coastal resources, are some of the issues that threaten the delicate balance of nature and the sea coast. The sicilian coastal areas most subject to erosion are those in Ragusa shores areas in south-eastern of Sicily, where the critical areas interesting low coastline and high shores. Following the coast, between Capo Peloro and Milazzo (Messina),where the erosion affects the coast with a low of about 23 km. In the coastal between Capo St. Marco and Capo Feto (Trapani) the critical areas interesting the low coastline and, in part erodible bluffs. One of this case is localized in the town of Mazara del Vallo. In general, the phenomenon erosive affects almost all the sicilian coastal units, in low-coastline and mountainous, with average rates of 29%. The main methods available today for the protection of coastlines in Sicily, are falling in the first approximation in hard (structural), and soft and soft, based not only on nutrition artificial beaches but also on interventions with low environmental impact as the reduction of losses sediments. The right approach is not only in stabilizing the various shores, but also in not induce or accelerate the erosion of the adjacent areas. Indeed this impact accompanies almost all the hard interventions achieved in past years. It is essential to carry out a verification of the effectiveness of the defence of the coast from erosion and structural interventions of nourishment in terms of impact on coastal marine and coastal environment. We started a series of experimental analysis based on the application of new techniques for relief based on remote sensing as the major techniques performed with satellite radar (SAR), measurements morph-altitude high resolution made with the laser system by plane (LIDAR) and precise measurements on the behaviour of works and river mouths with intelligences cameras. The most dominant climate change involve the precipitation and temperature. Temperature is particularly important in snow-dominated basins and in coastal areas, the latter due to the impact of temperature on sea level. Moreover we must say that (as mentioned in 4th Report IPCC) the shores are projected to be exposed to increasing risks, including coastal erosion, due to climate change and sea level rise. Infrastructure in coastal areas is vulnerable to damage from sea-level rise, flooding, and other storms. This effect will be exacerbated by increasing human-induced pressures on coastal areas. Keywords: erosion, shores, coastal defend, monitoring.

Coastline planning and management through digital mapping systems

NASA Astrophysics Data System (ADS)

Hysenaj, M.

2015-11-01

Albania is a country with a coastline of 316 km. The potentiality offered turns into a determinant factor for the Albanian economy. However specific issues need a solution. One of them remains the shoreline pollution. It affects mostly foreign visitors, also local population which recently tends to avoid attending these areas, instead they frequent foreign places. The importance of GIS technology in the water sector is undisputed. This paper will present a full set of digital maps representing a complete picture of the Albanian shoreline situation. The entire coastline is divided into the major frequented areas with a spatial extension based mainly on district level.

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2014 CFR

2014-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2013 CFR

2013-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2011 CFR

2011-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

7 CFR 12.22 - Highly erodible field determination criteria.

Code of Federal Regulations, 2012 CFR

2012-01-01

... percent or more of the total field acreage is identified as soil map units which are highly erodible; or (2) 50 or more acres in such field are identified as soil map units which are highly erodible. (b...

Dioxin-ähnliche Wirkungen durch Grundwasser am Industriestandort Zeitz

NASA Astrophysics Data System (ADS)

Schirmer, Kristin; Bopp, Stephanie; Russold, Sandra; Popp, Peter

Kurzfassung Im Rahmen der Etablierung des Standortes Zeitz (Sachsen-Anhalt) als Referenztestfeld zur Implementierung des Natural-Attenuation-Ansatzes, haben wir Grundwasser auf seine Fähigkeit untersucht, eine Dioxin-ähnliche Wirkung hervorzurufen. Die Dioxin-ähnliche Wirkung ist die Arylhydrocarbon Rezeptor-vermittelte Induktion des Proteinkomplexes Cytochrom CYP1A, welches als 7-Ethoxyresorufin-O-Deethylase (EROD) Enzymaktivität in einer Fischleberzelllinie gemessen wurde. Von 32 Probennahmestellen wiesen sieben eine signifikante EROD-Induktion auf, welche zu einem geringen Teil auf Polyzyklische Aromatische Kohlenwasserstoffe zurückzuführen war. Ein weiterer Teil der EROD-Induktion konnte den Substanzen Benzofuran, Indan und Inden zugesprochen werden, welche hier erstmalig als EROD-Induktoren identifiziert wurden. Alle Probennahmestellen mit signifikanter EROD-Induktion lagen im Anstrom bzw. westlich des früheren Standortes der Benzolanlage in Zeitz, was einen signifikanten Einfluss von Benzol vor allem auf den Transport und das Lösungsverhalten EROD-induzierender Grundwasserkontaminanten vermuten lässt. Insgesamt zeigen diese Untersuchungen, wie eine Kombination von chemischer und biologischer Analytik zu einer deutlich verbesserten Aussagekraft führt und somit zu einer nachhaltigen Überwachung der Qualität von Grundwasser beitragen kann. As part of setting up the test field Zeitz (Saxony-Anhalt, Germany) as a reference site for the implementation of Natural Attenuation as a remediation option, we have investigated groundwater for its ability to cause a dioxin-like response. The dioxin-like response is the aryl hydrocarbon receptor-mediated induction of the protein complex cytochrome CYP1A, which was measured as 7-Ethoxyresorufin-O-deethylase (EROD) enzyme activity in a fish liver cell line. Out of 32 sampling locations, seven showed significant EROD induction, which could be explained, to a minor extent, by the presence of polycyclic aromatic hydrocarbons. Another small portion of the EROD induction was attributed to the low molecular weight compounds, Benzofuran, Indane and Indene, which were shown for the first time to act as EROD inducers. All sampling locations showing significant EROD induction were located upstream or to the west of the former benzene production site in Zeitz. This indicates that benzene is likely to affect the transport and dissolution of EROD-inducing groundwater contaminants. In sum, this study shows how a combination of chemical and biological analysis can greatly augment knowledge about site characteristics and thus contribute to a sustainable monitoring of groundwater quality.

Deglacial remobilization of permafrost carbon to sediments along the East Siberian Arctic Seas

NASA Astrophysics Data System (ADS)

Martens, J.; Wild, B.; Bröder, L.; Andersson, A.; Pearce, C.; O'Regan, M.; Jakobsson, M.; Tesi, T.; Muschitiello, F.; Sköld, M.; Semiletov, I. P.; Dudarev, O.; Gustafsson, O.

2017-12-01

Current climate change is expected to thaw large quantities of permafrost carbon (PF-C) and expose it to degradation which emits greenhouse gases (i.e. CO2 and CH4). Warming causes a gradual deepening of the seasonally thawed active layer surface of permafrost soils, but also the abrupt collapse of deeper Ice Complex Deposits (ICD), especially along Siberian coastlines. It was recently hypothesized that past warming already induced large-scale permafrost degradation after the last glacial, which ultimately amplified climate forcing. We here assess the mobilization of PF-C to East Siberian Arctic Sea sediments during these warming periods. We perform source apportionment using bulk carbon isotopes (ΔΔ14C, δ13C) together with terrestrial biomarkers (CuO-derived lignin phenols) as indicators for PF-C transfer. We apply these techniques to sediment cores (SWERUS-L2) from the Chukchi Sea (4-PC1) and the southern Lomonosov Ridge (31-PC1). We found that PF-C fluxes during the Bølling-Allerød warming (14.7 to 12.7 cal ka BP), the Younger Dryas cooling (12.7 to 11.7 cal ka BP) and the early Holocene warming (until 11 cal ka BP) were overall higher than mid and late Holocene fluxes. In the Chukchi Sea, PF-C burial was 2x higher during the deglaciation (7.2 g m-2 a-1) than in the mid and late Holocene (3.6 g m-2 a-1), and ICD were the dominant source of PF-C (79.1%). Smaller fractions originated from the active layer (9.1%) and marine sources (11.7%). We conclude that thermo-erosion of ICD released large amounts of PF-C to the Chukchi Sea, likely driven by climate warming and the deglacial sea level rise. This contrasts to earlier analyses of Laptev Sea sediments where active layer material from river transport dominated the carbon flux. Preliminary data on lignin phenol concentrations of Lomonosov Ridge sediments suggest that the postglacial remobilization of PF-C was one order of magnitude higher (10x) than during both the preceding glacial and the subsequent Holocene. We will apply source apportionments between coastal erosion of ICD and river export of active layer material for the outer East Siberian Arctic Seas. Our findings demonstrate remobilization of PF-C during past warming events and suggest that current climate change might cause a similar cascade of permafrost destabilization and, thus, accelerate climate warming.

Statistical analysis of cyprinid ethoxyresorufin-O-deethylase data in a large French watershed.

PubMed

Flammarion, P; Migeon, B; Garric, J

1998-01-01

A comparison of ethoxyresorufin-O-deethylase (EROD) data collected in 1995 in various sites in the Rhône watershed (France) was carried out to quantify the influence of factors such as contamination and biological parameters on EROD levels and within-group variabilities. Three species of cyprinids were collected and fish chemical contamination was measured. A log transformation of EROD data provided both normalization and homogeneity of variances. The influence of female sexual maturation on the variability and EROD dimorphism was quantified. A relationship with contaminant bioaccumulation was observed. A comparison with EROD data collected during previous studies by the same laboratory was made to validate the results.

Onshore Wind Stress and Buoyancy Flux Observed on a Dissipative Mediterranean Beach

DTIC Science & Technology

2015-12-01

a climatologically Mediterranean coastline to explore the wind stress and buoyancy flux. An eddy covariance system was deployed in the intertidal... climatologically Mediterranean coastline to explore the wind stress and buoyancy flux. An eddy covariance system was deployed in the intertidal zone

Relationship between soil erodibility and modeled infiltration rate in different soils

NASA Astrophysics Data System (ADS)

Wang, Guoqiang; Fang, Qingqing; Wu, Binbin; Yang, Huicai; Xu, Zongxue

2015-09-01

The relationship between soil erodibility, which is hard to measure, and modeled infiltration rate were rarely researched. Here, the soil erodibility factors (K and Ke in the USLE, Ki and K1 in the WEPP) were calculated and the infiltration rates were modeled based on the designed laboratory simulation experiments and proposed infiltration model, in order to build their relationship. The impacts of compost amendment on the soil erosion characteristics and relationship were also studied. Two contrasting agricultural soils (bare and cultivated fluvo-aquic soils) were used, and different poultry compost contents (control, low and high) were applied to both soils. The results indicated that the runoff rate, sediment yield rate and soil erodibility of the bare soil treatments were generally higher than those of the corresponding cultivated soil treatments. The application of composts generally decreased sediment yield and soil erodibility but did not always decrease runoff. The comparison of measured and modeled infiltration rates indicated that the model represented the infiltration processes well with an N-S coefficient of 0.84 for overall treatments. Significant negative logarithmic correlations have been found between final infiltration rate (FIR) and the four soil erodibility factors, and the relationship between USLE-K and FIR demonstrated the best correlation. The application of poultry composts would not influence the logarithmic relationship between FIR and soil erodibility. Our study provided a useful tool to estimate soil erodibility.

Estimating eroded soil and predicting further erosion in Daisetsuzan National Park in Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Kobayashi, Yusuke; Watanabe, Teiji

2017-04-01

This study has three objectives: (1) to estimate changes of the eroded volume of mountain trails from 2014 to 2016 by making DSMs, (2) to understand a relationship between the trail erosion and micro-topography, and (3) to predict the volume of soil that can be eroded in future. Trail erosion has been investigated near Mt. Hokkai-dake in Daisetzuzan National Park, Hokkaido, northern Japan, with a drone (UAV) from 2014 to 2016. Seven segments with the soil erosion from starting sites to ending sites were selected to make DSMs and Orthophotographs by Agisoft, which is one of the Structure from Motion (SfM) software. Then, at fourteen points in each of the seven segments were selected to estimate the volume of soil that can be eroded in the future by PANDA2, a soil compaction penetrometer. The eroded volume in the segment with the largest eroded value attained 274.67 m3 for the two-year period although extremely heavy rain hit this area in the 2016 summer. The result obtained by PANDA2 shows that soil more than 100 cm in depth will be potentially eroded at four points in three years to one hundred years.

Impact assessment of a wastewater treatment plant effluent using the fish biomarker ethoxyresorufin-O-deethylase: field and on-site experiments.

PubMed

Kosmala, A; Migeon, B; Flammarion, P; Garric, J

1998-09-01

The impact of a wastewater treatment plant (WWTP) effluent was assessed with the fish biomarker ethoxyresorufin-O-deethylase (EROD) using field and on-site laboratory experiments. EROD activity was measured in chub (Leuciscus cephalus) and stone loach (Noemacheilus barbatulus) caught at three sites of the Chalaronne River (southeast France). Liver somatic index (LSI) and organochloride bioaccumulation in muscle were estimated for chub only. In September, EROD activity and LSI of chub increased significantly between the sites above and below the WWTP effluent discharge. EROD induction detected in chub was confirmed by on-site tank experiments. EROD levels were determined in juvenile rainbow trout (Oncorhynchus mykiss) and mirror carp (Cyprinus carpio) exposed to different concentrations of the WWTP effluent and river water for 16 days. After a 4-day exposure, EROD activities of the carp exposed to the effluent increased significantly compared with the control. The response was linked to the effluent concentration and was stable with exposure time. WWTP effluent induced EROD activity, whereas organic and metal analyses, performed on fish muscle and sediment, did not indicate any difference between upstream and downstream of the discharge. Copyright 1998 Academic Press.

EROD activity measured in flatfish from the area of the Sea Empress oil spill.

PubMed

Kirby, M F; Neall, P; Tylor, T

1999-05-01

Dab (Limanda limanda) and plaice (Pleuronectes platessa) were collected at five stations near to the site of the Sea Empress oil spill within two weeks of the incident and a further fourteen stations three months after the spillage. Ethoxyresorufin-O-deethylase (EROD) activity was determined in the livers of the specimens to determine whether induction could be detected. Statistically significant inter-site differences in EROD levels in both species were demonstrated. Elevated levels of EROD activity in dab were found at the two stations nearest to the incident up to three months after the spill but no clear relationship to putative contaminant levels was determined. EROD levels in plaice showed a generally similar pattern of induction as in dab. Correlation of EROD levels with other variables showed that sexual maturity had the greatest influence on dab during the study period. The plaice specimens were sexually immature and, therefore, did not demonstrate a corresponding relationship. It was concluded that, for EROD monitoring purposes, fish should be sampled during their sexually inactive phase and that close attention needs to be paid to other variables (depth, temperature, GSI, length, influential contaminants etc.) when interpreting the results.

Soil erodibility variability in laboratory and field rainfall simulations

NASA Astrophysics Data System (ADS)

Szabó, Boglárka; Szabó, Judit; Jakab, Gergely; Centeri, Csaba; Szalai, Zoltán

2017-04-01

Rainfall simulation experiments are the most common way to observe and to model the soil erosion processes in in situ and ex situ circumstances. During modelling soil erosion, one of the most important factors are the annual soil loss and the soil erodibility which represent the effect of soil properties on soil loss and the soil resistance against water erosion. The amount of runoff and soil loss can differ in case of the same soil type, while it's characteristics determine the soil erodibility factor. This leads to uncertainties regarding soil erodibility. Soil loss and soil erodibility were examined with the investigation of the same soil under laboratory and field conditions with rainfall simulators. The comparative measurement was carried out in a laboratory on 0,5 m2, and in the field (Shower Power-02) on 6 m2 plot size where the applied slope angles were 5% and 12% with 30 and 90 mm/h rainfall intensity. The main idea was to examine and compare the soil erodibility and its variability coming from the same soil, but different rainfall simulator type. The applied model was the USLE, nomograph and other equations which concern single rainfall events. The given results show differences between the field and laboratory experiments and between the different calculations. Concerning for the whole rainfall events runoff and soil loss, were significantly higher at the laboratory experiments, which affected the soil erodibility values too. The given differences can originate from the plot size. The main research questions are that: How should we handle the soil erodibility factors and its significant variability? What is the best solution for soil erodibility determination?

Temporal changes of ethoxyresorufin-o-deethylase (EROD) activities and lysosome accumulation in intestine of fish on chronic exposure to dietary benzo[a]pyrene: linking erod induction to cytological effects.

PubMed

Yuen, Bonny B H; Au, Doris W T

2006-10-01

Temporal changes of intestinal and hepatic ethoxyresorufin-O-deethylase (EROD) activities and quantitative changes of secondary and tertiary (e.g., 2 degrees/3 degrees) lysosomes in enterocytes were compared for the juvenile grouper (Epinephelus coioides) on chronic exposure to foodborne benzo[a]pyrene (BaP) at two environmentally realistic levels (0.25 and 12.5 microg/g fish/d) over a four-week exposure and four-week depuration period. Intestinal EROD induction was rapid (within 3 d) and sustained in the BaP-exposed fish, while a fast recovery (within one week) was observed on withdrawal of BaP intake. A dose-response relationship was demonstrated between intestinal EROD activities and the levels of foodborne BaP. Conversely, hepatic EROD induction was weak and subsided rapidly in the exposed fish, signifying that hepatic EROD activity is not a good indicator of oral intake of BaP. Significant increase of 2 degrees/3 degrees lysosomes, as measured by Vv(lysosome, mucosa), was detected in young enterocytes of fish in the high-dosing group (12.5 microg/g fish/d) at exposure day 3 and persisted until recovery week 2. Importantly, intestinal EROD activity was significantly correlated to 2 degrees/3 degrees lysosome accumulation in enterocytes (r = 0.571, p < 0.001). These results further corroborate our earlier findings that induction of EROD activities in fish do not merely indicate exposure to BaP but also are correlated to harmful biological effects. We recommend the use of these two biochemical and cytological changes in intestines as specific biomarkers to indicate current and recent exposure of fish to BaP via oral intake.

Measurement of historical cliff-top changes and estimation of future trends using GIS data between Bridlington and Hornsea - Holderness Coast (UK)

NASA Astrophysics Data System (ADS)

Castedo, Ricardo; de la Vega-Panizo, Rogelio; Fernández-Hernández, Marta; Paredes, Carlos

2015-02-01

A key requirement for effective coastal zone management is good knowledge of historical rates of change and the ability to predict future shoreline evolution, especially for rapidly eroding areas. Historical shoreline recession analysis was used for the prediction of future cliff shoreline positions along a section of 9 km between Bridlington and Hornsea, on the northern area of the Holderness Coast, UK. The analysis was based on historical maps and aerial photographs dating from 1852 to 2011 using the Digital Shoreline Analysis System (DSAS) 4.3, extension of ESRI's ArcInfo 10.×. The prediction of future shorelines was performed for the next 40 years using a variety of techniques, ranging from extrapolation from historical data, geometric approaches like the historical trend analysis, to a process-response numerical model that incorporates physically-based equations and geotechnical stability analysis. With climate change and sea-level rise implying that historical rates of change may not be a reliable guide for the future, enhanced visualization of the evolving coastline has the potential to improve awareness of these changing conditions. Following the IPCC, 2013 report, two sea-level rise rates, 2 mm/yr and 6 mm/yr, have been used to estimate future shoreline conditions. This study illustrated that good predictive models, once their limitations are estimated or at least defined, are available for use by managers, planners, engineers, scientists and the public to make better decisions regarding coastal management, development, and erosion-control strategies.

Spatial distribution of loggerhead turtle (Caretta caretta) emergences along a highly dynamic beach in the northern Gulf of Mexico

USGS Publications Warehouse

Lamont, Margaret M.; Houser, Chris

2014-01-01

As coastlines change due to sea level rise and an increasing human presence, understanding how species, such as marine turtles, respond to alterations in habitat is necessary for proper management and conservation. Survey data from a major nesting beach in the northern Gulf of Mexico, where a revetment was installed, was used to assess spatial distribution of loggerhead emergences. Through use of Quadrat analysis and piecewise linear regression with breakpoint, we present evidence to suggest that nest site selection in loggerheads is determined in the nearshore environment, and by characteristics such as wave height, alongshore currents, depth and patterns of erosion and accretion. Areas of relatively dense nesting were found in areas with relatively strong alongshore currents, relatively small waves, a steep offshore slope and the largest historical rates of erosion. Areas of relatively dense nesting also corresponded to areas of low nesting success. Both nesting and non-nesting emergences were clustered immediately adjacent to the revetment and at other eroding sites along the beach. These results suggest that alterations to the nearshore environment from activities such as construction of a jetty, dredging or installation of pilings, may impact sea turtle nest distribution alongshore. We also show that piecewise linear regression with breakpoint is a technique that can be used with geomorphological and oceanographic data to predict locations of nest clumping and may be useful for managers at other nesting beaches.

Linking Backbarrier Lacustrine Stratigraphy with Spatial Dynamics of Shoreline Retreat in a Rapidly Subsiding Region of the Mississippi River Delta

NASA Astrophysics Data System (ADS)

Dietz, M.; Liu, K. B.; Bianchette, T. A.; Yao, Q.

2017-12-01

The shoreline along the northern Gulf of Mexico is rapidly retreating as coastal features of abandoned Mississippi River delta complexes erode and subside. Bay Champagne is located in the Caminada-Moreau headland, a region of shoreline west of the currently active delta that has one of the highest rates of retreat and land loss. As a result, this site has transitioned from a stable, circular inland lake several kilometers from the shore to a frequently perturbed, semi-circular backbarrier lagoon, making it ideal to study the environmental effects of progressive land loss. Analyses of clastic layers in a series of sediment cores collected at this site over the past decade indicate the lake was less perturbed in the past and has become increasingly more sensitive to marine incursion events caused by tropical cyclones. Geochemical and pollen analyses of these cores also reveal profound changes in environmental and chemical conditions in Bay Champagne over the past century as the shoreline has retreated. Through relating stratigraphy to spatial changes observed from satellite imagery, this study attempts to identify the tipping point at which Bay Champagne began the transition from an inland lake to a backbarrier environment, and to determine the rate at which this transition occurred. Results will be used to develop a model of the environmental transition experienced by a rapidly retreating coastline and to predict how other regions of the Mississippi River deltaic system could respond to future shoreline retreat.

Cryptic vicariance in Gulf of California fishes parallels vicariant patterns found in Baja California mammals and reptiles.

PubMed

Riginos, Cynthia

2005-12-01

Comparisons across multiple taxa can often clarify the histories of biogeographic regions. In particular, historic barriers to movement should have affected multiple species and, thus, result in a pattern of concordant intraspecific genetic divisions among species. A striking example of such comparative phylogeography is the recent observation that populations of many small mammals and reptiles living on the Baja California peninsula have a large genetic break between northern and southern peninsular populations. In the present study, I demonstrate that five species of near-shore fishes living on the Baja coastline of the Gulf of California share this genetic pattern. The simplest explanation for this concordant genetic division within both terrestrial and marine vertebrates is that the Baja Peninsula was fragmented by a Plio-Pleistocene marine seaway and that this seaway posed a substantial barrier to movement for near-shore fishes. For some fish species, the signal of this vicariance in mtDNA has been eroded by gene flow and is not evident with classic, equilibrium measures of population structure. Yet, significant divisions are apparent in coalescent analyses that jointly estimate divergence with gene flow. The genetic divisions within Gulf of California fishes also coincide with recognized biogeographic regions based on fish community composition and several environmental factors. It is likely that adaptation to regional environments and present-day oceanographic circulation limit gene exchange between biogeographic regions and help maintain evidence of past vicariance.

An analysis on half century morphological changes in the Changjiang Estuary: Spatial variability under natural processes and human intervention

NASA Astrophysics Data System (ADS)

Zhao, Jie; Guo, Leicheng; He, Qing; Wang, Zheng Bing; van Maren, D. S.; Wang, Xianye

2018-05-01

Examination of large scale, alluvial estuarine morphology and associated time evolution is of particular importance regarding management of channel navigability, ecosystem, etc. In this work, we analyze morphological evolution and changes of the channel-shoal system in the Changjiang Estuary, a river- and tide-controlled coastal plain estuary, based on bathymetric data between 1958 and 2016. We see that its channel-shoal pattern is featured by meandering and bifurcated channels persisting over decades. In the vertical direction, hypsometry curves show that the sand bars and shoals are continuously accreted while the deep channels are eroded, leading to narrower and deeper estuarine channels. Intensive human activities in terms of reclamation, embankment, and dredging play a profound role in controlling the decadal morphological evolution by stabilizing coastlines and narrowing channels. Even though, the present Changjiang Estuary is still a pretty wide and shallow system with channel width-to-depth ratios >1000, much larger than usual fluvial rivers and small estuaries. In-depth analysis suggests that the Changjiang Estuary as a whole exhibited an overall deposition trend over 59 years, i.e., a net deposition volume of 8.3 × 108 m3. Spatially, the pan-South Branch was net eroded by 9.7 × 108 m3 whereas the mouth bar zone was net deposited by 18 × 108 m3, suggesting that the mouth bar zone is a major sediment sink. Over time there is no directional deposition or erosion trend in the interval though riverine sediment supply has decreased by 2/3 since the mid-1980s. We infer that the pan-South Branch is more fluvial-controlled therefore its morphology responds to riverine sediment load reduction fast while the mouth bar zone is more controlled by both river and tides that its morphological response lags to riverine sediment supply changes at a time scale >10 years, which is an issue largely ignored in previous studies. We argue that the time lag effect needs particular consideration in projecting future estuarine morphological changes under a low sediment supply regime and sea-level rise. Overall, the findings in this work can have implications on management of estuarine ecosystem, navigation channel and coastal flooding in general.

Arctic and Arctic-like rabies viruses: distribution, phylogeny and evolutionary history

PubMed Central

KUZMIN, I. V.; HUGHES, G. J.; BOTVINKIN, A. D.; GRIBENCHA, S. G.; RUPPRECHT, C. E.

2008-01-01

SUMMARY Forty-one newly sequenced isolates of Arctic and Arctic-like rabies viruses, were genetically compared to each other and to those available from GenBank. Four phylogenetic lineages of Arctic viruses were identified. Arctic-1 viruses circulate in Ontario, Arctic-2 viruses circulate in Siberia and Alaska, Arctic-3 viruses circulate circumpolarly, and a newly described lineage Arctic-4 circulates locally in Alaska. The oldest available isolates from Siberia (between 1950 and 1960) belong to the Arctic-2 and Arctic-3 lineages and share 98·6–99·2% N gene identity with contemporary viruses. Two lineages of Arctic-like viruses were identified in southern Asia and the Middle East (Arctic-like-1) and eastern Asia (Arctic-like-2). A time-scaled tree demonstrates that the time of the most recent common ancestor (TMRCA) of Arctic and Arctic-like viruses is dated between 1255 and 1786. Evolution of the Arctic viruses has occurred through a northerly spread. The Arctic-like-2 lineage diverged first, whereas Arctic viruses share a TMRCA with Arctic-like-1 viruses. PMID:17599781

Arctic and Arctic-like rabies viruses: distribution, phylogeny and evolutionary history.

PubMed

Kuzmin, I V; Hughes, G J; Botvinkin, A D; Gribencha, S G; Rupprecht, C E

2008-04-01

Forty-one newly sequenced isolates of Arctic and Arctic-like rabies viruses, were genetically compared to each other and to those available from GenBank. Four phylogenetic lineages of Arctic viruses were identified. Arctic-1 viruses circulate in Ontario, Arctic-2 viruses circulate in Siberia and Alaska, Arctic-3 viruses circulate circumpolarly, and a newly described lineage Arctic-4 circulates locally in Alaska. The oldest available isolates from Siberia (between 1950 and 1960) belong to the Arctic-2 and Arctic-3 lineages and share 98.6-99.2% N gene identity with contemporary viruses. Two lineages of Arctic-like viruses were identified in southern Asia and the Middle East (Arctic-like-1) and eastern Asia (Arctic-like-2). A time-scaled tree demonstrates that the time of the most recent common ancestor (TMRCA) of Arctic and Arctic-like viruses is dated between 1255 and 1786. Evolution of the Arctic viruses has occurred through a northerly spread. The Arctic-like-2 lineage diverged first, whereas Arctic viruses share a TMRCA with Arctic-like-1 viruses.

46 CFR 28.120 - Survival craft.

Code of Federal Regulations, 2013 CFR

2013-10-01

.... Beyond Boundary Line, within 12 miles of coastline, cold waters Less than 10.97 meters (36 feet) in... than 10.97 meters (36 feet) in length Buoyant apparatus.See note 2. Great Lakes, beyond 3 miles of... Boundary Line, within 12 miles of coastline, cold waters 10.97 meters (36 feet) or more in length Buoyant...

46 CFR 28.120 - Survival craft.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... Beyond Boundary Line, within 12 miles of coastline, cold waters Less than 10.97 meters (36 feet) in... than 10.97 meters (36 feet) in length Buoyant apparatus.See note 2. Great Lakes, beyond 3 miles of... Boundary Line, within 12 miles of coastline, cold waters 10.97 meters (36 feet) or more in length Buoyant...

46 CFR 28.120 - Survival craft.

Code of Federal Regulations, 2012 CFR

2012-10-01

.... Beyond Boundary Line, within 12 miles of coastline, cold waters Less than 10.97 meters (36 feet) in... than 10.97 meters (36 feet) in length Buoyant apparatus.See note 2. Great Lakes, beyond 3 miles of... Boundary Line, within 12 miles of coastline, cold waters 10.97 meters (36 feet) or more in length Buoyant...

46 CFR 28.120 - Survival craft.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... Beyond Boundary Line, within 12 miles of coastline, cold waters Less than 10.97 meters (36 feet) in... than 10.97 meters (36 feet) in length Buoyant apparatus.See note 2. Great Lakes, beyond 3 miles of... Boundary Line, within 12 miles of coastline, cold waters 10.97 meters (36 feet) or more in length Buoyant...

Exposure of coastal built assets in the South Pacific to climate risks

NASA Astrophysics Data System (ADS)

Kumar, Lalit; Taylor, Subhashni

2015-11-01

Pacific island countries (PICs) are situated in a highly dynamic ocean-atmosphere interface, are dispersed over a large ocean area, and have highly populated urban centres located on the coastal margin. The built infrastructure associated with urban centres is also located within close proximity to the coastlines, exposing such infrastructure to a variety of natural and climate change-related hazards. In this research we undertake a comprehensive analysis of the exposure of built infrastructure assets to climate risk for 12 PICs. We show that 57% of the assessed built infrastructure for the 12 PICs is located within 500 m of their coastlines, amounting to a total replacement value of US$21.9 billion. Eight of the 12 PICs have 50% or more of their built infrastructure located within 500 m of their coastlines. In particular, Kiribati, Marshall Islands and Tuvalu have over 95% of their built infrastructure located within 500 m of their coastlines. Coastal adaptation costs will require substantial financial resources, which may not be available in developing countries such as the PICs, leaving them to face very high impacts but lacking the adaptive capacity.

Coupled economic-coastline modeling with suckers and free riders

NASA Astrophysics Data System (ADS)

Williams, Zachary C.; McNamara, Dylan E.; Smith, Martin D.; Murray, A. Brad.; Gopalakrishnan, Sathya

2013-06-01

erosion is a natural trend along most sandy coastlines. Humans often respond to shoreline erosion with beach nourishment to maintain coastal property values. Locally extending the shoreline through nourishment alters alongshore sediment transport and changes shoreline dynamics in adjacent coastal regions. If left unmanaged, sandy coastlines can have spatially complex or simple patterns of erosion due to the relationship of large-scale morphology and the local wave climate. Using a numerical model that simulates spatially decentralized and locally optimal nourishment decisions characteristic of much of U.S. East Coast beach management, we find that human erosion intervention does not simply reflect the alongshore erosion pattern. Spatial interactions generate feedbacks in economic and physical variables that lead to widespread emergence of "free riders" and "suckers" with subsequent inequality in the alongshore distribution of property value. Along cuspate coastlines, such as those found along the U.S. Southeast Coast, these long-term property value differences span an order of magnitude. Results imply that spatially decentralized management of nourishment can lead to property values that are divorced from spatial erosion signals; this management approach is unlikely to be optimal.

Paleo-environment Simulation using GIS based on Shell Mounds

NASA Astrophysics Data System (ADS)

Uchiyama, T.; Asanuma, I.; Harada, E.

2016-02-01

Paleo-coastlines are simulated using the geographic information system (GIS) based on the shell mounds as the paleo-environment in the Tsubaki-no-umi, Ocean of Camellia in Japanese, the paleo-ocean, in Japan. The shell mounds, which are introduced in the paleo-study in the class history in junior and senior high, are used to estimate the paleo-coastlines. The paleo-coastlines are simulated as the function of sea levels relative to the current sea level for 6000 to 3000 BP on the digital elevation map of the GIS. The polygon of the simulated sea level height of 10 m extracted the shell mounds during 6000 to 5500 BP as the result of the spatial operation, and exhibited the consistency with the previous studies. The simulated sea level height of 5.5 m showed the paleo-coastline during 3600 to 3220 BP, while the Tsubaki-no-Umiturned into the brackish water lake, partly isolated from the ocean. The simulation of sea levels with GIS could be implemented to the class in the junior and senior high school with minimum efforts of teachers with the available computer and software environments.

Mechanisms of wave‐driven water level variability on reef‐fringed coastlines

USGS Publications Warehouse

Buckley, Mark L.; Lowe, Ryan J.; Hansen, Jeff E; van Dongeren, Ap R.; Storlazzi, Curt

2018-01-01

Wave‐driven water level variability (and runup at the shoreline) is a significant cause of coastal flooding induced by storms. Wave runup is challenging to predict, particularly along tropical coral reef‐fringed coastlines due to the steep bathymetric profiles and large bottom roughness generated by reef organisms, which can violate assumptions in conventional models applied to open sandy coastlines. To investigate the mechanisms of wave‐driven water level variability on a reef‐fringed coastline, we performed a set of laboratory flume experiments on an along‐shore uniform bathymetric profile with and without bottom roughness. Wave setup and waves at frequencies lower than the incident sea‐swell forcing (infragravity waves) were found to be the dominant components of runup. These infragravity waves were positively correlated with offshore wave groups, signifying they were generated in the surf zone by the oscillation of the breakpoint. On the reef flat and at the shoreline, the low‐frequency waves formed a standing wave pattern with energy concentrated at the natural frequencies of the reef flat, indicating resonant amplification. Roughness elements used in the flume to mimic large reef bottom roughness reduced low frequency motions on the reef flat and reduced wave run up by 30% on average, compared to the runs over a smooth bed. These results provide insight into sea‐swell and infragravity wave transformation and wave setup dynamics on steep‐sloped coastlines, and the effect that future losses of reef bottom roughness may have on coastal flooding along reef‐fringed coasts.

75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-07

... Wind Erosion Prediction System for Soil Erodibility System Calculations for the Natural Resources... Erosion Prediction System (WEPS) for soil erodibility system calculations scheduled for implementation for... computer model is a process-based, daily time-step computer model that predicts soil erosion via simulation...

Induction of EROD and BFCOD activities in tissues of barbel (Barbus callensis) from a water reservoir in Algeria.

PubMed

Habila, Safia; Leghouchi, Essaid; Valdehita, Ana; Bermejo-Nogales, Azucena; Khelili, Smail; Navas, José M

2017-08-01

EROD and BFCOD activities were measured in liver and gills of barbel (Barbus callensis, a native North African species) captured at Beni Haroun lake, the most important water reservoir in Algeria. This lake receives wastewater from different origins. Thus, we assessed the level of pollution through the induction of detoxification activities in tissues of barbel, evaluating simultaneously the suitability of this species to be used as a sentinel. Fish were collected between March 2015 and January 2016 at three locations taking into account the pollution sources and accessibility. In liver, EROD and BFCOD showed the highest induction in October specially in the location of the dam that received pollutants. In gills, only EROD, but not BFCOD, activity was detected. Maximal EROD induction was noted in samples from January. Fish cell lines (RTG-2 and PLHC-1) were exposed to sediments extracts collected at Beni Haroun lake and enzyme activities (EROD and BFCOD, respectively) were measured. Sediment extracts did not induce BFCOD activity. The EROD induction observed in RTG-2 cells was in line with the results observed in fish tissues. Our results suggest that the lake is at risk from pollution and that Barbus callensis is a good sentinel species. Copyright © 2017 Elsevier Inc. All rights reserved.

Rock Erodibility as a Dynamic Variable Driven by the Interplay between Erosion and Weathering in Bedrock Channels: Examples from Great Falls, Virginia, USA

NASA Astrophysics Data System (ADS)

Hancock, G. S.; Huettenmoser, J.; Shobe, C. M.; Eppes, M. C.

2016-12-01

Rock erodibility in channels is a primary control on the stresses required to erode bedrock (e.g., Sklar and Dietrich, 2001). Erodibility tends to be treated as a uniform and fixed variable at the scale of channel cross-sections, particularly in models of channel profile evolution. Here we present field data supporting the hypothesis (Hancock et al., 2011) that erodibility is a dynamic variable, driven by the interplay between erosion rate and weathering processes within cross-sections. We hypothesize that rock weathering varies in cross-sections from virtually unweathered in the thalweg, where frequent stripping removes weathered rock, to a degree of weathering determined by the frequency of erosive events higher on the channel margin. We test this hypothesis on three tributaries to the Potomac River underlain by similar bedrock but with varying erosion rates ( 0.01 to 0.8 m/ky). At multiple heights within three cross-sections on three tributaries, we measured compressive strength with a Schmidt hammer, surface roughness with a contour gage, and density and length of visible cracks. Compressive strength decreased with height in all nine cross-sections by 10% to 50%, and surface roughness increased with height in seven cross-sections by 25% - 45%, with the remaining two showing minimal change. Crack density increased with height in the three cross-sections measured. Taken together these data demonstrate increases in weathering intensity, and presumably, rock erodibility, with height. The y-intercept of the relation between height and the three measured variables were nearly identical, suggesting that thalweg erodibility was similar on each channel, as predicted, even though erodibility higher in the cross-section were markedly different. The rate at which the three variables changed with height in each cross-section is strongly related to stream power. Assuming stream power is a reasonable surrogate for erosion rate, this result implies that erosion rate can be a primary influence on the distribution of erodibility within channel cross-sections. We conclude that the interplay between rates of erosion and weathering produces spatial as well as temporal variability in erodibility which, in turn, influences channel form and gradient.

Leopard frog PCB levels and evaluation of EROD as a biomarker in Green Bay ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Y.W.; Karasov, W.H.; Patnode, K.P.

1995-12-31

The induction of mixed function oxidases has been shown to be a promising biomarker in many taxa of wildlife, though not yet tested for amphibians. The three hypotheses tested in this study were (1) activities of hepatic EROD of leopard frog (Rana pipiens) are induced following exposure to planar chlorinated PCBs, (2) tissue PCB residue levels of leopard frogs are positively correlated with their wetland sediment PCB levels, and (3) EROD activities are positively correlated with tissue PCB concentrations and sediment PCB. In the laboratory, EROD was increased 2--3 times seven days after i.p. injection with PCB 126 at dosesmore » {ge} 2.3 ppm (wet mass basis). Leopard frogs from seven sites along the Lower Fox River and Green Bay in 1994--1995 were assayed for hepatic EROD activities and total PCB levels in carcasses. Tissue PCB levels ranged from 3 to 152 ppb (including coplanar congeners) and were highest from sites with higher sediment PCB. EROD activity in frogs collected in August--September was not significantly correlated with frog body mass and was similar among sites with one exception. There was no significant correlation between EROD activity and tissue PCB concentration. This result was consistent with the fact that the frogs collected from the Green Bay ecosystem had relatively low PCB levels compared with what was required for induction in the laboratory. The authors conclude that EROD activity is not a sensitive biomarker of PCB exposure in leopard frogs in this ecosystem.« less

Variations in Soil Properties and Herbicide Sorption Coefficients with Depth in Relation to PRZM (Pesticide Root Zone Model) Calculations

USDA-ARS?s Scientific Manuscript database

There are few experimental data available on how herbicide sorption coefficients change across small increments within soil profiles. Soil profiles were obtained from three landform elements (eroded upper slope, deposition zone, and eroded waterway) in a strongly eroded agricultural field and segmen...

Development a fluvial detachment rate model to predict the erodibility of cohesive soils under the influence of seepage

USDA-ARS?s Scientific Manuscript database

Seepage influences the erodibility of streambanks, streambeds, dams, and embankments. Usually the erosion rate of cohesive soils due to fluvial forces is computed using an excess shear stress model, dependent on two major soil parameters: the critical shear stress (tc) and the erodibility coefficie...

Soil wind erodibility based on dry aggregate-size distribution in the Tarim Basin

USDA-ARS?s Scientific Manuscript database

The Tarim Basin is an important source of airborne particulate matter that contributes to poor air quality in China. However, little attention has been given to estimating wind erodibility of soils in the region. The objective of this study was to determine the soil wind erodibility for six land use...

Oregon's Ever-Changing Coastline. Another Title in the Series "Learning About the Ocean."

ERIC Educational Resources Information Center

Katz, Barbara A.; Gabriel, Stephen R.

This bulletin contains a non-technical introduction to the forces that change the coastline and how engineers can sometimes modify their effects with occasionally unpredicted consequences. This publication introduces the reader to the basic geology of the Oregon coast. Next, an explanation of wave action discussing the changes in a beach due to…

Instantaneous Coastline Extraction from LIDAR Point Cloud and High Resolution Remote Sensing Imagery

NASA Astrophysics Data System (ADS)

Li, Y.; Zhoing, L.; Lai, Z.; Gan, Z.

2018-04-01

A new method was proposed for instantaneous waterline extraction in this paper, which combines point cloud geometry features and image spectral characteristics of the coastal zone. The proposed method consists of follow steps: Mean Shift algorithm is used to segment the coastal zone of high resolution remote sensing images into small regions containing semantic information;Region features are extracted by integrating LiDAR data and the surface area of the image; initial waterlines are extracted by α-shape algorithm; a region growing algorithm with is taking into coastline refinement, with a growth rule integrating the intensity and topography of LiDAR data; moothing the coastline. Experiments are conducted to demonstrate the efficiency of the proposed method.

Polycyclic aromatic and aliphatic hydrocarbons in Chukchi Sea biota and sediments and their toxicological response in the Arctic cod, Boreogadus saida

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger; Taylor, Karen A.; Pie, Hannah V.; Mitchelmore, Carys L.

2014-04-01

As part of the Chukchi Sea Offshore Monitoring in Drilling Area-Chemical and Benthos (COMIDA CAB) project, we determined the distribution and concentrations of aliphatic n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in surface sediments (0-1 cm) among 52 sites across the Chukchi Sea and in muscle tissues of the benthic Northern whelk, Neptunea heros, collected opportunistically. In addition, downcore profiles of contaminants were determined at three targeted sites to establish historic patterns. Baseline responses of PAH exposure and its potential toxicological effects were examined in the common Arctic cod, Boreogadus saida, through measures of cytochrome P4501A/ ethoxyresorufin O-deethylase (CYP1A/EROD), glutathione-S-transferase (GST), and Cu/Zn superoxide dismutase (SOD) activity in liver tissue. The total concentration of PAHs in surface sediments throughout the study area, including parent and alkyl-homologs, were very low (<1600 ng g-1 dry wt) except for a single station, where values were 2-20-fold greater than at other baseline sites (2956 ng g-1 dry wt). Alkyl-substituted PAHs were the dominant form in all surface (54-93%) and subsurface sediments (50-81% of the total), with a general decrease in total PAH concentrations observed downcore. In biota, larger Neptunea showed lower total concentrations of PAHs in foot muscles (4.5-10.7 ng g-1 wet wt) compared to smaller animals; yet aliphatic n-alkane (C19-C33) concentrations (0.655-5.20 μg g-1 wet wt) increased in larger organisms with distributions dominated by long-chain (C23-C33) hydrocarbons. In B. saida, CYP1A1, GST, and SOD enzyme levels were comparable to baseline levels previously reported in other pristine systems. Of the three assays, only SOD had a significant correlation between gene expression and enzyme activity.

Paleoenvironmental analyses of an organic deposit from an erosional landscape remnant, Arctic Coastal Plain of Alaska

USGS Publications Warehouse

Eisner, Wendy R.; Bockheim, James G.; Hinkel, Kenneth M.; Brown, Thomas A.; Nelson, Frederick E.; Peterson, Kim M.; Jones, Benjamin M.

2005-01-01

The dominant landscape process on the Arctic Coastal Plain of northern Alaska is the formation and drainage of thaw lakes. Lakes and drained thaw-lake basins account for approximately 75% of the modern surface expression of the Barrow Peninsula. The thaw-lake cycle usually obliterates lacustrine or peat sediments from previous cycles, which could otherwise be used for paleoecological reconstruction of long-term landscape and vegetation changes. Several possible erosional remnants of a former topographic surface that predates the formation of the thaw lakes have been tentatively identified. These remnants are characterized by a higher elevation, a thick organic layer with very high ground ice content in the upper permafrost and a plant community somewhat atypical of the region. Ten soil cores were collected from one site, and one core was intensively sampled for soil organic carbon content, pollen analysis and 14C dating. The lowest level of the organic sediments represents the earliest phase of plant growth and dates to ca. 9000 cal BP. Palynological evidence indicates the presence of mesic shrub tundra (including sedge, birch, willow and heath vegetation), and microfossil indicators point to wetter eutrophic conditions during this period. Carbon accumulation was rapid due to high net primary productivity in a relatively nutrient-rich environment. These results are interpreted as the local response to ameliorating climate during the early Holocene. The middle Holocene portion of the record contains an unconformity, indicating that between 8200 and 4200 cal BP sediments were eroded from the site, presumably in response to wind activity during a drier period centered around 4500 cal BP. The modern vegetation community of the erosional remnant was established after 4200 cal BP and peat growth resumed. During the late Holocene, carbon accumulation rates (CARs) were greatly reduced in response to the combined effects of declining productivity associated with climatic cooling, and increased nutrient stress as paludification and permafrost aggradation sequestered mineral nutrients.

Carbon and nitrogen mobilization along thermokarst-affected permafrost coasts and its degradation mechanisms before entering the near shore zone

NASA Astrophysics Data System (ADS)

Tanski, G.; Ruttor, S.; Lantuit, H.; Knoblauch, C.; Strauss, J.; Radosavljevic, B.; Ramage, J. L.; Fritz, M.

2016-12-01

The Arctic is more than any other region on Earth affected by changing climate conditions. Ice-rich and unlithified permafrost coasts are particularly susceptible for these changes. These coasts erode at a great pace, which is facilitated by thermokarst processes and wave action due to longer open water periods. Organic matter that has been frozen for millennia is mobilized and can be either emitted as greenhouse gases to the atmosphere, redeposited on the land surface, or transported into the nearshore zone of the ocean. However, only little is known about the degradation processes after mobilization from permafrost until entering the aquatic system. It is the aim of this study to capture the degradation dynamics of organic carbon and nitrogen at the land-ocean-interface before entering nearshore zone, where it can potentially affect marine chemistry and ecosystems. In this study we investigated a retrogressive thaw slump, a thermokarst feature that is abundant along the ice-rich permafrost coast of the Canadian Arctic. Samples have been taken systematically along transects in undisturbed, i.e. not affected by thermokarst yet (tundra, permafrost headwall), and disturbed areas (mudpool, slump deposits, thaw stream). Total and dissolved organic carbon (TOC and DOC) as well as total and dissolved nitrogen (TN and DN) were analyzed to estimate the loss from undisturbed to disturbed areas. Stable carbon isotopes, C/N-ratios, inorganic nutrients, and lipid biomarkers have been analyzed to determine potential degradation processes. The results show no substantial changes of stable carbon isotopes and C/N-ratios (for TOC). However, high concentrations of ammonium in the mudpool (fresh thawed material) and low C/N-rations (for DOC) within the thaw stream indicate rapid metabolization of organic material. In conclusion we show that organic carbon and nutrients undergo substantial changes upon thaw and are subject to degradation before entering the nearshore zone.

Chukchi Borderland | Crustal Complex of the Amerasia Basin, Arctic Ocean

NASA Astrophysics Data System (ADS)

Ilhan, I.; Coakley, B.; Houseknecht, D. W.

2017-12-01

In the Arctic Ocean, Chukchi Borderland separates the North Chukchi shelf and Toll deep basins to the west and Canada deep basin to the east. Existing plate reconstructions have attempted to restore this north-striking, fragments of the continental crust to all margins of the Amerasia Basin based on sparse geologic and geophysical measurements. Regional multi-channel seismic reflection and potential field geophysics, and geologic data indicate it is a high standing continental block, requiring special accommodation to create a restorable model of the formation of the Amerasia Basin. The Borderland is composed of the Chukchi Plateau, Northwind Basin, and Northwind Ridge divided by mostly north striking normal faults. These offset the basement and bound a sequence of syn-tectonic sediments. Equivalent strata are, locally, uplifted, deformed and eroded. Seaward dipping reflectors (SDRs) are observed in the juncture between the North Chukchi, Toll basins, and southern Chukchi Plateau underlying a regional angular unconformity. This reveals that this rifted margin was associated with volcanism. An inferred condensed section, which is believed to be Hauterivian-Aptian in age, synchronous with the composite pebble shale and gamma-ray zone of the Alaska North Slope forms the basal sediments in the North Chukchi Basin. Approximately 15 km of post-rift strata onlap the condensed section, SDRs and, in part, the wedge sequence on the Chukchi Plateau from west to east, thinning to the north. These post-Aptian sediments imply that the rifted margin subsided no later than the earliest Cretaceous, providing a plausible time constraint for the inferred pre-Cretaceous rifting in this region. The recognition of SDRs and Hauterivian—Aptian condensed section, and continuity of the Early—Late Cretaceous post-rift strata along the margins of the Borderland, strike variations of the normal faults, absence of observable deformation along the Northwind Escarpment substantially constrain tectonic models proposed for tectonic development of the Amerasia Basin. Models that require significant relative motion between the Chukchi Shelf and Borderland since the Early Cretaceous are precluded by these observations.

Paleoenvironmental analyses of an organic deposit from an erosional landscape remnant, Arctic Coastal Plain of Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisner, W R; Bockheim, J G; Hinkel, K M

2005-01-02

The dominant landscape process on the Arctic Coastal Plain of northern Alaska is the formation and drainage of thaw lakes. Lakes and drained thaw lake basins account for approximately 75% of the modern surface expression of the Barrow Peninsula. The thaw lake cycle usually obliterates lacustrine or peat sediments from previous cycles which could otherwise be used for paleoecological reconstruction of long-term landscape and vegetation changes. Several possible erosional remnants of a former topographic surface that predates the formation of the thaw lakes have been tentatively identified. These remnants are characterized by a higher elevation, a thick organic layer withmore » very high ground ice content in the upper permafrost, and a plant community somewhat atypical of the region. Ten soil cores were collected from one site, and one core was intensively sampled for soil organic carbon content, pollen analysis, and {sup 14}C dating. The lowest level of the organic sediments represents the earliest phase of plant growth and dates to ca. 9000 cal BP. Palynological evidence indicates the presence of mesic shrub tundra (including sedge, birch, willow, and heath vegetation); and microfossil indicators point to wetter eutrophic conditions during this period. Carbon accumulation was rapid due to high net primary productivity in a relatively nutrient-rich environment. These results are interpreted as the local response to ameliorating climate during the early Holocene. The middle Holocene portion of the record contains an unconformity, indicating that between 8200 and 4200 cal BP sediments were eroded from the site, presumably in response to wind activity during a drier period centered around 4500 cal BP. The modern vegetation community of the erosional remnant was established after 4200 cal BP, and peat growth resumed. During the late Holocene, carbon accumulation rates were greatly reduced in response to the combined effects of declining productivity associated with climatic cooling, and increased nutrient stress as paludification and permafrost aggradation sequestered mineral nutrients.« less

Soil erodibility in Europe: a high-resolution dataset based on LUCAS.

PubMed

Panagos, Panos; Meusburger, Katrin; Ballabio, Cristiano; Borrelli, Pasqualle; Alewell, Christine

2014-05-01

The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. One key parameter for modelling soil erosion is the soil erodibility, expressed as the K-factor in the widely used soil erosion model, the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). The K-factor, which expresses the susceptibility of a soil to erode, is related to soil properties such as organic matter content, soil texture, soil structure and permeability. With the Land Use/Cover Area frame Survey (LUCAS) soil survey in 2009 a pan-European soil dataset is available for the first time, consisting of around 20,000 points across 25 Member States of the European Union. The aim of this study is the generation of a harmonised high-resolution soil erodibility map (with a grid cell size of 500 m) for the 25 EU Member States. Soil erodibility was calculated for the LUCAS survey points using the nomograph of Wischmeier and Smith (1978). A Cubist regression model was applied to correlate spatial data such as latitude, longitude, remotely sensed and terrain features in order to develop a high-resolution soil erodibility map. The mean K-factor for Europe was estimated at 0.032 thahha(-1)MJ(-1)mm(-1) with a standard deviation of 0.009 thahha(-1)MJ(-1)mm(-1). The yielded soil erodibility dataset compared well with the published local and regional soil erodibility data. However, the incorporation of the protective effect of surface stone cover, which is usually not considered for the soil erodibility calculations, resulted in an average 15% decrease of the K-factor. The exclusion of this effect in K-factor calculations is likely to result in an overestimation of soil erosion, particularly for the Mediterranean countries, where highest percentages of surface stone cover were observed. Copyright © 2014. Published by Elsevier B.V.

Pyrosequencing reveals bacteria carried in different wind-eroded sediments.

PubMed

Gardner, Terrence; Acosta-Martinez, Veronica; Calderón, Francisco J; Zobeck, Ted M; Baddock, Matthew; Van Pelt, R Scott; Senwo, Zachary; Dowd, Scot; Cox, Stephen

2012-01-01

Little is known about the microbial communities carried in wind-eroded sediments from various soil types and land management systems. The novel technique of pyrosequencing promises to expand our understanding of the microbial diversity of soils and eroded sediments because it can sequence 10 to 100 times more DNA fragments than previous techniques, providing enhanced exploration into what microbes are being lost from soil due to wind erosion. Our study evaluated the bacterial diversity of two types of wind-eroded sediments collected from three different organic-rich soils in Michigan using a portable field wind tunnel. The wind-eroded sediments evaluated were a coarse sized fraction with 66% of particles >106 μm (coarse eroded sediment) and a finer eroded sediment with 72% of particles <106 μm. Our findings suggested that (i) bacteria carried in the coarser sediment and fine dust were effective fingerprints of the source soil, although their distribution may vary depending on the soil characteristics because certain bacteria may be more protected in soil surfaces than others; (ii) coarser wind-eroded sediment showed higher bacterial diversity than fine dust in two of the three soils evaluated; and (iii) certain bacteria were more predominant in fine dust (, , and ) than coarse sediment ( and ), revealing different locations and niches of bacteria in soil, which, depending on wind erosion processes, can have important implications on the soil sustainability and functioning. Infrared spectroscopy showed that wind erosion preferentially removes particular kinds of C from the soil that are lost via fine dust. Our study shows that eroded sediments remove the active labile organic soil particulates containing key microorganisms involved in soil biogeochemical processes, which can have a negative impact on the quality and functioning of the source soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

An assessment of the erodibility of Holocene lithounits comprising streambanks in northeastern Kansas, USA

NASA Astrophysics Data System (ADS)

Layzell, Anthony L.; Mandel, Rolfe D.

2014-05-01

Streambanks are the primary source of sediment for watersheds in the Midwestern USA. In much of this region, deposits of fine-grained Holocene alluvium comprising streambanks have been assigned to a single lithostratigraphic unit, the DeForest Formation. This study examines the stratigraphic relationships and measures the erodibility of the different members of the DeForest Formation in three watersheds in northeastern Kansas. Distinct differences in erodibility, measured in terms of critical shear stress (τc) by a submerged jet-test device, were observed between the different members of the DeForest Formation. The most erodible member is the Camp Creek Member (average τc = 1.0 Pa) while the most resistant is the Gunder Member (average τc = 10.4 Pa). Variability in erodibility between and within the members of the DeForest Formation is attributed to the magnitude of post-depositional soil-forming processes, including the presence of buried soils, as well as the inherent natural variability in the different parent materials. A weak positive correlation was found between percent clay and τc. Resistance to erosion by fluid flow was found to be significantly greater where clay contents exceed 28%. Although the Camp Creek Member was found to be the most erodible, it always occurs, stratigraphically, as the uppermost member. Available bankfull stage indicators suggest that bankfull discharges rarely attain elevations sufficient to erode Camp Creek Member deposits. Therefore, other members of the DeForest Formation are able to exert some control on the rate of bank erosion by hydraulic flow. Furthermore, given the observed differences in lithology, soil development and erodibility, the susceptibility to mass wasting processes is also likely to vary between the different members. Therefore, lithostratigraphic and soil-stratigraphic relationships have important implications for streambank erodibility and are crucial for accurately determining areas prone to streambank erosion in alluvial settings.

Silver Creek: A Study of Stream Velocities and Erosion along the Ohio River near Clarksville, Indiana; McAlpine Lock and Dam Numerical Model

DTIC Science & Technology

2018-04-12

split between the upper and lower gates, the tainter gate outflow can cause flow circulations or eddies to form , which requires the use of a multi...determined to not erode were assigned a bed layer thickness of zero. This included the stone weir, fossil beds, non-erodible vegetation, and upstream...606.7 Chute 0.1 606 L 0.4 Erodible Small Vegetation 606.7 Chute 0.1 606 L 0.4 Fossil Bed NA 0 NA 0 Non Erodible Small Vegetation NA 0 NA 0 Non

Erodibility of waste (Loess) soils from construction sites under water and wind erosional forces.

PubMed

Tanner, Smadar; Katra, Itzhak; Argaman, Eli; Ben-Hur, Meni

2018-03-01

Excess soils from construction sites (waste soils) become a problem when exposed to soil erosion by water or wind. Understanding waste soil erodibility can contribute to its proper reuse for various surface applications. The general objective of the study was to provide a better understanding of the effects of soil properties on erodibility of waste soils excavated from various depths in a semiarid region under rainfall and wind erosive forces. Soil samples excavated from the topsoil (0-0.3m) and subsoil layers (0.3-0.9 and >1m depths) were subjected to simulated rainfall and wind. Under rainfall erosive forces, the subsoils were more erodible than the topsoil, in contrast to the results obtained under wind erosive forces. Exchangeable sodium percentage was the main factor controlling soil erodibility (K i ) under rainfall, and a significant logarithmic regression line was found between these two parameters. In addition, a significant, linear regression was found between K i and slaking values for the studied soil samples, suggesting that the former can be predicted from the latter. Soil erodibility under wind erosion force was controlled mainly by the dry aggregate characteristics (mean weight diameter and aggregate density): their higher values in the subsoil layers resulted in lower soil erodibility compared to the topsoil. Copyright © 2017 Elsevier B.V. All rights reserved.

Multi-centennial Record of Labrador Sea Primary Productivity and Sea-Ice Variability Archived in Coralline Algal Ba/Ca

NASA Astrophysics Data System (ADS)

Chan, Phoebe; Halfar, Jochen; Adey, Walter; Hetzinger, Steffen; Zack, Thomas; Moore, Kent; Wortmann, Ulrich; Williams, Branwen; Hou, Alicia

2017-04-01

Arctic sea-ice thickness and concentration have dropped by approximately 9% per decade since 1978. Concurrent with this sea-ice decline is an increase in rates of phytoplankton productivity, driven by shoaling of the mixed layer and enhanced transmittance of solar radiation into the surface ocean. This has recently been confirmed by phytoplankton studies in Arctic and Subarctic basins that have revealed earlier timing, prolonged duration, and increased primary productivity of the spring phytoplankton bloom. However, difficulties of navigating in remote ice-laden waters and harsh polar climates have often resulted in short and incomplete records of in-situ plankton abundance in the northwestern Labrador Sea. Alternatively, information of past ocean productivity may be gained through the study of trace nutrient distributions in the surface water column. Investigations of dissolved barium (Ba) concentrations in the Arctic reveal significant depletions of Ba in surface seawaters due to biological scavenging during the spring phytoplankton bloom. Here we apply a barium-to-calcium (Ba/Ca) and carbon isotope (δ13C) multiproxy approach to long-lived crustose coralline algae in order to reconstruct an annually-resolved multi-centennial record of Labrador Sea productivity related to sea-ice variability in Labrador, Canada that extends well into the Little Ice Age (LIA; 1646 AD). The crustose coralline alga Clathromorphum compactum is a shallow marine calcareous plant that is abundant along the eastern Canadian coastline, and produces annual growth increments which allow for the precise calendar dating and geochemical sampling of hard tissue. Algal Ba/Ca ratios can serve as a promising new proxy for surface water productivity, demonstrating a close correspondence to δ13C that does not suffer from the anthropogenically-induced carbon isotope decline (ex. Suess Effect) beginning in the 1960s. Coralline algal Ba/Ca demonstrates statistically significant correlations to both observational and proxy records of sea-ice extent and transport variability, and shows a persistent pattern of covariability that is broadly consistent with the timing and phasing of the Atlantic Multidecadal Oscillation (AMO). Lower algal Ba/Ca values are interpreted as increased productivity (via biological scavenging) coinciding with warming sea surface temperatures and melting of sea-ice, and vice versa. This relationship is further supported by negative correlations between algal Ba/Ca and spatially averaged chlorophyll α concentrations determined from Sea-Viewing Wide Field-of-View Sensor (SeaWiFS; 1998 - 2009) ocean colour data. Extended comparisons to a multi-centennial tree-ring proxy AMO index demonstrates more frequent positive Ba/Ca excursions (indicating reduced productivity) associated with AMO cool phases during the Little Ice Age, followed by a step-wise decline in Ba/Ca (indicating increasing productivity) from 1910 to present levels - unprecedented in the last 365 years. Our multi-centennial record of coralline algal Ba/Ca in the Subarctic northwest Atlantic demonstrates a long-term increasing trend in primary productivity that is in agreement with recent satellite-based productivity in the Arctic Ocean. This ongoing increase in phytoplankton productivity is expected to fundamentally alter marine biodiversity and trophic dynamics as warming and freshening of the surface layer is projected to intensify over the coming century.

Value-Eroding Teacher Behaviors Scale: A Validity and Reliability Study

ERIC Educational Resources Information Center

Arseven, Zeynep; Kiliç, Abdurrahman; Sahin, Seyma

2016-01-01

In the present study, it is aimed to develop a valid and reliable scale for determining value-eroding behaviors of teachers, hence their values of judgment. The items of the "Value-eroding Teacher Behaviors Scale" were designed in the form of 5-point likert type rating scale. The exploratory factor analysis (EFA) was conducted to…

DNA sequence database as a tool to identify decapod crustaceans on the São Paulo coastline.

PubMed

Mantelatto, Fernando L; Terossi, Mariana; Negri, Mariana; Buranelli, Raquel C; Robles, Rafael; Magalhães, Tatiana; Tamburus, Ana Francisca; Rossi, Natália; Miyazaki, Mayara J

2017-09-05

DNA barcoding has emerged as an efficient tool for taxonomy and other biodiversity fields. The vast and speciose group of decapod crustaceans is not an exception in the current scenario and comparing short DNA fragments has enabled researchers to overcome some taxonomic impediments to help broadening knowledge on the diversity of this group of crustaceans. Brazil is considered as an important area in terms of global marine biodiversity and some regions stand out in terms of decapod fauna, such as the São Paulo coastline. Thus, the aim of this study is to obtain sequences of the mitochondrial markers (COI and 16S) for decapod crustaceans distributed at the São Paulo coastline and to test the accuracy of these markers for species identification from this region by comparing our sequences to those already present in the GenBank database. We sampled along almost the 300 km of the São Paulo coastline from estuaries to offshore islands during the development of a multidisciplinary research project that took place for 5 years. All the species were processed to obtain the DNA sequences. The diversity of the decapod fauna on the São Paulo coastline comprises at least 404 species. We were able to collect 256 of those species and sequence of at least one of the target genes from 221. By testing the accuracy of these two DNA markers as a tool for identification, we were able to check our own identifications, including new records in GenBank, spot potential mistakes in GenBank, and detect potential new species.

Monitoring the changing position of coastlines using aerial and satellite image data: an example from the eastern coast of Trabzon, Turkey.

PubMed

Sesli, Faik Ahmet; Karsli, Fevzi; Colkesen, Ismail; Akyol, Nihat

2009-06-01

Coastline mapping and coastline change detection are critical issues for safe navigation, coastal resource management, coastal environmental protection, and sustainable coastal development and planning. Changes in the shape of coastline may fundamentally affect the environment of the coastal zone. This may be caused by natural processes and/or human activities. Over the past 30 years, the coastal sites in Turkey have been under an intensive restraint associated with a population press due to the internal and external touristic demand. In addition, urbanization on the filled up areas, settlements, and the highways constructed to overcome the traffic problems and the other applications in the coastal region clearly confirm an intensive restraint. Aerial photos with medium spatial resolution and high resolution satellite imagery are ideal data sources for mapping coastal land use and monitoring their changes for a large area. This study introduces an efficient method to monitor coastline and coastal land use changes using time series aerial photos (1973 and 2002) and satellite imagery (2005) covering the same geographical area. Results show the effectiveness of the use of digital photogrammetry and remote sensing data on monitoring large area of coastal land use status. This study also showed that over 161 ha areas were filled up in the research area and along the coastal land 12.2 ha of coastal erosion is determined for the period of 1973 to 2005. Consequently, monitoring of coastal land use is thus necessary for coastal area planning in order to protecting the coastal areas from climate changes and other coastal processes.

Soil aggregation, erodibility, and erosion rates in mountain soils (NW Alps, Italy)

NASA Astrophysics Data System (ADS)

Stanchi, S.; Falsone, G.; Bonifacio, E.

2015-04-01

Erosion is a relevant soil degradation factor in mountain agrosilvopastoral ecosystems that can be enhanced by the abandonment of agricultural land and pastures left to natural evolution. The on-site and off-site consequences of soil erosion at the catchment and landscape scale are particularly relevant and may affect settlements at the interface with mountain ecosystems. RUSLE (Revised Universal Soil Loss Equation) estimates of soil erosion consider, among others, the soil erodibility factor (K), which depends on properties involved in structure and aggregation. A relationship between soil erodibility and aggregation should therefore be expected. However, erosion may limit the development of soil structure; hence aggregates should not only be related to erodibility but also partially mirror soil erosion rates. The aim of the research was to evaluate the agreement between aggregate stability and erosion-related variables and to discuss the possible reasons for discrepancies in the two kinds of land use considered (forest and pasture). Topsoil horizons were sampled in a mountain catchment under two vegetation covers (pasture vs. forest) and analyzed for total organic carbon, total extractable carbon, pH, and texture. Soil erodibility was computed, RUSLE erosion rate was estimated, and aggregate stability was determined by wet sieving. Aggregation and RUSLE-related parameters for the two vegetation covers were investigated through statistical tests such as ANOVA, correlation, and regression. Soil erodibility was in agreement with the aggregate stability parameters; i.e., the most erodible soils in terms of K values also displayed weaker aggregation. Despite this general observation, when estimating K from aggregate losses the ANOVA conducted on the regression residuals showed land-use-dependent trends (negative average residuals for forest soils, positive for pastures). Therefore, soil aggregation seemed to mirror the actual topsoil conditions better than soil erodibility. Several hypotheses for this behavior were discussed. A relevant effect of the physical protection of the organic matter by the aggregates that cannot be considered in K computation was finally hypothesized in the case of pastures, while in forests soil erodibility seemed to keep trace of past erosion and depletion of finer particles. A good relationship between RUSLE soil erosion rates and aggregate stability occurred in pastures, while no relationship was visible in forests. Therefore, soil aggregation seemed to capture aspects of actual vulnerability that are not visible through the erodibility estimate. Considering the relevance and extension of agrosilvopastoral ecosystems partly left to natural colonization, further studies on litter and humus protective action might improve the understanding of the relationship among erosion, erodibility, and structure.

Effect of CPP-ACP on the remineralization of acid-eroded human tooth enamel: nanomechanical properties and microtribological behaviour study

NASA Astrophysics Data System (ADS)

Zheng, L.; Zheng, J.; Zhang, Y. F.; Qian, L. M.; Zhou, Z. R.

2013-10-01

Casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP) has been used to enhance tooth remineralization in the dental clinic. But the contribution of CPP-ACP to the remineralization of acid-eroded human tooth enamel is of widespread controversy. To confirm the application potential of CPP-ACP in the remineralization repair of tooth erosion caused by acid-attack, the effect of remineralization in vitro in 2% w/v CPP-ACP solution on the acid-eroded human tooth enamel was investigated in this study. The repair of surface morphology and the improvement of nanomechanical and microtribological properties were characterized with laser confocal scanning microscope, scanning electron microscope, nanoindentation tester and nanoscratch tester. Results showed that a layer of uneven mineral deposits, which were mainly amorphous calcium phosphate (ACP) in all probability, was observed on the acid-eroded enamel surface after remineralization. Compared with the acid-eroded enamel surface, the nanoindentation hardness and Young's modulus of the remineralized enamel surface obviously increased. Both the friction coefficient and wear volume of the acid-eroded enamel surface decreased after remineralization. However, both the nanomechanical and the anti-wear properties of the remineralized enamel surface were still inferior to those of original enamel surface. In summary, tooth damage caused by acid erosion could be repaired by remineralization in CPP-ACP solution, but the repair effect, especially on the nanomechanical and anti-wear properties of the acid-eroded enamel, was limited. These results would contribute to a further exploration of the remineralization potential of CPP-ACP and a better understanding of the remineralization repair mechanism for acid-eroded human tooth enamel.

High Nutrient Load Increases Biostabilization of Sediment by Biofilms

NASA Astrophysics Data System (ADS)

Valentine, K.; Mariotti, G.

2016-12-01

Benthic biofilms, matrixes of microbial cells and their secretions, have been shown to stabilize sediment in coastal environments. While there have been numerous studies on the effects of nutrients on the ability of vascular plants to stabilize sediment, few studies have investigated how nutrients affect biofilm growth and their ability to stabilize sediment. Diatom-based biofilms were grown in laboratory experiments on a settled bed of bentonite clay, under a saline water column with varying amounts of nutrients. Erodibility at different stages of biofilm growth was measured using a Gust Erosion Microcosm System, which applied shear stresses from 0.05 to 0.6 Pa. Biofilms more than one week old decreased the erodibility of the sediments in all nutrient treatments compared to abiotic experiments. With high nutrients, the biofilm grew the fastest; the erodibility decreased within two weeks of biofilm growth and remained low for all applied shear stresses. After four weeks of biofilm growth, no erosion of sediment occurred even at the highest applied shear stress (0.6 Pa). With low nutrients the erodibility decreased within three weeks. With no nutrients the biofilms grew similarly to those with low nutrients; the erodibility decreased within three weeks under shear stresses 0.05-0.45 Pa, but the sediments were eroded under high shear stresses. Under low to moderate shear stresses (0.05-0.45 Pa), the total mass eroded by all experiments with biofilms was similar, suggesting that any amount of biofilm decreases erodibility at low shear stresses. In summary, high nutrients allow for faster biostabilization and for resistance to extreme shear stresses. These results suggest that eutrophication would not decrease the biofilm ability to stabilize muddy sediments in coastal environment.

Response of Muddy Sediments and Benthic Diatom-based Biofilms to Repeated Erosion Events

NASA Astrophysics Data System (ADS)

Valentine, K.; Mariotti, G.; Fagherazzi, S.

2016-02-01

Benthic biofilms, microbes aggregated within a matrix of Extracellular Polymeric Substances (EPS), are commonly found in shallow coastal areas and intertidal environments. Biofilms have the potential to stabilize sediments, hence reducing erosion and possibly mitigating land loss. The purpose of this study is to determine how repeated flow events that rework the bed affect biofilm growth and its ability to stabilize cohesive sediments. Natural mud devoid of grazers was used to create placed beds in four annular flumes; biofilms were allowed to grow on the sediment surface. Each flume was eroded at different time intervals (1 or 12 days) to allow for varied levels of biofilm growth and adjustment following erosion. In addition, experiments with abiotic mud were performed by adding bleach to the tank. Each erosion test consisted of step-wise increases in flow that were used to measured erodibility. In the experiments where the bed was eroded every day both the abiotic and biotic flumes exhibited a decrease in erodibility with time, likely due to consolidation, but the decrease in erodibility was greater in the flume with a biofilm. Specifically the presence of biofilm reduced bed erosion at low shear stresses ( 0.1 Pa). We attribute this progressive decrease in erodibility to the accumulation of EPS over time: even though the biofilm was eroded during each erosion event, the EPS was retained within the flume, mixed with the eroded sediment and eventually settled. Less frequent erosion allowed the growth of a stronger biofilm that decreased bed erosion at higher shear stresses ( 0.4 Pa). We conclude that the time between destructive flow events influences the ability of biofilms to stabilize sediments. This influence will likely be affected by biofilm growth conditions such as light, temperature, nutrients, salinity, and the microbial community.

Huo Hsing Vallis

NASA Technical Reports Server (NTRS)

2002-01-01

(Released 5 June 2002) The Science A portion of an ancient channel called the Huo Hsing Vallis seen in the center of this image. As with all channel forms on Mars, it was carved by some moving fluid but that fluid can not automatically be assumed to be water. Lava and even wind can sculpt channel forms that mimic those of flowing water. In this case, the presence of pronounced oxbow bends in the channel favors the conclusion that water was the fluid. It is interesting that the ripple-like ridges on the channel floor mimic current ripples found in many streams on Earth. But the fluid responsible for their formation likely is the wind. Similar ripples occur in many places on Mars that have no relationship to channels. Surrounding the channel is an intensely eroded landscape known as etched terrain. The many layers that were deposited in the past are now being eroded away by the wind. In the process, unusual polygonal ridges are being exposed, the most prominent of which appear just north of the oxbow bends. The mechanism by with they form is poorly understood. It is possible that they began as polygonal troughs similar in form and origin as those that form in permafrost regions on Earth like the Canadian Arctic. If the troughs were subsequently filled in by sediment that solidified into a more resistant deposit than the surrounding material, later erosion would leave behind ridges in place of the former troughs. Known as inverted topography, there are examples of this type of landform in other etched terrains on Mars. The Story For thousands of years, many cultures the world over have studied the planets, first by observing their motions in the night sky, later through telescopes, and today through up-close observation enabled by spacecraft. Many places on Mars are given names that honor the long history of contributions by all peoples to Mars exploration. Huo Hsing, the Chinese word for the planet Mars, is the namesake of the ancient channel shown above. As with all channel forms on Mars, it was carved by a moving fluid. Sometimes the moving fluid that created the channels can be identified as water, sometimes as lava, and sometimes as something else entirely. Even the wind can carve out the terrain in grooves. So, how can you tell what force split the smoothness of the land? In this case, check out the tight, meandering loops called oxbow bends. This pattern suggests that water was the mysterious fluid. We frequently see such bends in rivers and floodplains on Earth. At the bottom of the empty channel, you can see rippling ridges. This undulating terrain is a dry mimic of the waves that once rippled on currents down the channel, but it wasn't water that shaped these landforms. They were created by the wind and occur not only in Martian channels, but all over the windswept red planet. Wind erosion is a geologist's friend, because it can uncover a planet's deeper secrets. What you can see all around the deeper channels is a terrain that seems almost 'flaky' in appearance. It's known as etched terrain and is created by the wind as it scours the planet again and again over the years, unevenly eroding the surface. The coolest thing in this image is that the wind has eroded enough material just north of the oxbow bends to reveal a crackly-patterned surface known as polygonal ridges. Why is that so interesting? While no one knows exactly how they formed, it's possible that they began as polygonal troughs similar to those that form in permafrost regions on Earth like the Canadian Arctic. At least on Earth, the formation of these polygons are directly linked to the repeated thawing and freezing of water and the stresses that puts on the surface. That gives scientists a further indication that water could have been more than an occasional force in molding this region. Whether water was the original culprit or not, it's wind that has taken over. You'll notice that while these 'crackly features' may have begun as troughs, their polygonal edges sure seem like they're slightly raised above the surrounding terrain. And they are! It's possible that the former troughs were filled in at some point by a strong, erosion-resistant deposit that eventually solidified over time. As the wind continued to shave away the surrounding terrain, ridges were left behind. These ridges are known as inverted topography, and occur in many etched terrains on Mars.

Molecular epidemiological study of Arctic rabies virus isolates from Greenland and comparison with isolates from throughout the Arctic and Baltic regions.

PubMed

Mansfield, K L; Racloz, V; McElhinney, L M; Marston, D A; Johnson, N; Rønsholt, L; Christensen, L S; Neuvonen, E; Botvinkin, A D; Rupprecht, C E; Fooks, A R

2006-03-01

We report a molecular epidemiological study of rabies in Arctic countries by comparing a panel of novel Greenland isolates to a larger cohort of viral sequences from both Arctic and Baltic regions. Rabies virus isolates originating from wildlife (Arctic/red foxes, raccoon-dogs and reindeer), from domestic animals (dogs/cats) and from two human cases were investigated. The resulting 400 bp N-gene sequences were compared with isolates representing neighbouring Arctic or Baltic countries from North America, the former Soviet Union and Europe. Phylogenetic analysis demonstrated similarities between sequences from the Arctic and Arctic-like viruses, which were distinct from rabies isolates originating in the Baltic region of Europe, the Steppes in Russia and from North America. The Arctic-like group consist of isolates from India, Pakistan, southeast Siberia and Japan. The Arctic group was differentiated into two lineages, Arctic 1 and Arctic 2, with good bootstrap support. Arctic 1 is mainly comprised of Canadian isolates with a single fox isolate from Maine in the USA. Arctic 2 was further divided into sub-lineages: 2a/2b. Arctic 2a comprises isolates from the Arctic regions of Yakutia in northeast Siberia and Alaska. Arctic 2b isolates represent a biotype, which is dispersed throughout the Arctic region. The broad distribution of rabies in the Arctic regions including Greenland, Canada and Alaska provides evidence for the movement of rabies across borders.

Too Warm, Two Poles: Super Interglacial Teleconnections and Possible Dual Pole Ice Sheet Stability

NASA Astrophysics Data System (ADS)

Brigham-Grette, J.; Deconto, R. M.; Roychowdhury, R.; de Wet, G.; Keisling, B. A.; Melles, M.; Minyuk, P.

2017-12-01

Geologic records of the warm Pliocene and Pleistocene super interglacials from both the Arctic and the Antarctic show us that ice sheets are more vulnerable to subtle polar warming than once thought. The continuous 3.6 million-year old sediment record from Lake El'gygytgyn (Lake E), the largest, deepest unglaciated Arctic lake located in central Chukotka, Russia, contains evidence of the warm forested Pliocene and the transition to changing glacial/interglacial climate cycles including at least 9 super interglacials and numerous other strong interglacials. Most of these super interglacials especially MIS 11 and 31, record conditions warmer than MIS 5e and many occur when global cycles are dominated by apparent 41ka forcing during the transition from the warm Pliocene to stronger G/IG variability. Given community consensus on the reduction of the Greenland Ice sheet (GIS) during MIS5e, we suggest that previous interglacials likely forced even larger reductions in the GIS, perhaps consistent with cosmogenic isotope exposure histories. We can best match MIS 11 and 31 from the Antarctic ANDRILL records when diatomaceous ooze deposition in the past recovered from under the modern Ross Ice Shelf suggests collapse of the WAIS and open water conditions. It is possible that a large number of the other Lake E super interglacials correspond to other intervals of WAIS collapse, within the uncertainly of the ANDRILL chronology. The forcing of super interglacials was not necessarily the result of high atmospheric CO2 but the result of preconditioning during periods of extremely low eccentricity and high obliquity. The challenge is now to incorporate oceanographic models (as suggested in Melles et al. 2012) to gauge ice sheet and ocean circulation sensitivity and timescales to preconditioning. Yet confirmation of past warming driving frequent ice sheet collapse in both hemispheres is clear geologically-based evidence that informs our future. Today, anthropogenic CO2 emissions are driving warming and accelerating ice sheet failure. Given that sea level rise projected into the future is global and not reversible, paleoclimate science should help drive social and political action aimed at short-term fixes and long-term "managed retreat" of human infrastructure from our coastlines.

Facilities Enhancement for IPY at Barrow

NASA Astrophysics Data System (ADS)

Sheehan, G.; Brown, J.; Coakley, B.; Zak, B.

2007-12-01

In connection with the International Polar Year, research facilities at Barrow have been markedly enhanced. On June 1st, Sen. Ted Stevens cut the ribbon at the Grand Opening of the Barrow Arctic Research Center (BARC). The BARC currently covers 18,000 sq. ft, with future phases anticipated, including 8 research labs, a necropsy lab for animal studies, freezers for biological samples, a state-of-the-art-data system, a planned Internet II connection, meeting spaces, and offices. There is a platform on the roof of the facility for instrumentation, and a communications tower to provide WIFI connections to remote instrumentation located on the adjacent Barrow Environmental Observatory (BEO). The BEO, which consists of 11 square miles of tundra and coastline set aside for environmental and ecological research, has also seen recent enhancements. A power line and a hard- surfaced trail now provide easy access to the interior of the BEO. Users of the BEO (and others) also have access to many different data sets continuously collected at the NOAA Global Monitoring Division Barrow Station and the DOE ARM (Atmospheric Radiation Measurement) Climate Research Facility (see http://www.esrl.noaa.gov/gmd/obop/brw.html and http://www.arm.gov/sites/nsa.stm respectively) also adjacent to the BEO. The National Weather Service Barrow Station also provides data of interest. Researchers submitting proposals to the National Science Foundation can include a request for the use of BARC and BEO facilities in their proposals. ARM facilities, recently augmented, can also be made available, but through arrangements made directly with ARM (BDZak@sandia.gov; 505-845-8631 or MDIvey@sandia.gov; 505-284-9092). BARC, BEO and ARM facilities are available to other agency and international users as well. For more information, see http://www.arcticscience.org, or contact Glenn Sheehan (907-852-4881, basc@arcticscience.org). The BEO consists of land owned by Ukpeagvik Inupiat Corporation, which is owned by the native people of Barrow. The BEO is administered by the Barrow Arctic Science Consortium (BASC) under a Cooperative Agreement with the National Science Foundation. BASC is a non-profit entity set up to serve the logistical needs of scientists doing research on the North Slope of Alaska.

The last interglacial in eastern Canada and the northwest North Atlantic : further evidence for warmer climate and ocean conditions than during the Holocene

NASA Astrophysics Data System (ADS)

de Vernal, A.; Fréchette, B.; Hillaire-Marcel, C.; van Nieuwenhove, N.; Retailleau, S.

2012-04-01

The climate conditions of the last interglacial (LI) in northeastern and southeastern Canada are documented from pollen data of Baffin Island and Cape Breton Island respectively. The LI pollen assemblages indicate very different vegetation than at present and a northern limit of the deciduous forest biome as far as 500 km north of its modern position. The application of the modern analogue technique also reveal warmer climate during the LI than at present, 4-5°C warmer on Baffin Island at ~67-70°N in the Canadian Arctic, and up to 7°C warmer on Cape Breton Island at ~45°N in the southeastern Canada. The contrast between LI and Holocene climates is also shown from marine data (dinocysts, foraminifers, oxygen and carbon isotopes) that document warmer than Holocene conditions in surface waters (up to 5.5°C in summer, notably off southwest Greenland) and very distinct distribution of intermediate to deep waters in northern and southern part of the Labrador Sea. An important zonal atmospheric circulation component at mid-latitudes of the North Atlantic is also evidenced from the pollen content of marine cores collected in central North Atlantic (IODP Site 1304), which strongly suggests an origin from southeastern Canada. Altogether the data demonstrate much warmer conditions along the eastern Canadian margins, from North to South. The mild conditions along the coastlines and the relatively warm waters off eastern Canada and southern Greenland suggest reduced Arctic outflow components through the East Greenland Current and Labrador Current. Comparisons with records from eastern North Atlantic lead us to conclude in a more zonal climate during the LI than the Holocene, especially the early Holocene that was marked by a particularly pronounced west to east gradient of temperatures. Hence, the thermal optimum of the LI and that of the Holocene provide two examples of very different climate and ocean circulation regimes in the circum-Atlantic region during the "warm" episodes of the recent geological past.

Thermodynamic and dynamic ice thickness contributions in the Canadian Arctic Archipelago in NEMO-LIM2 numerical simulations

NASA Astrophysics Data System (ADS)

Hu, Xianmin; Sun, Jingfan; Chan, Ting On; Myers, Paul G.

2018-04-01

Sea ice thickness evolution within the Canadian Arctic Archipelago (CAA) is of great interest to science, as well as local communities and their economy. In this study, based on the NEMO numerical framework including the LIM2 sea ice module, simulations at both 1/4 and 1/12° horizontal resolution were conducted from 2002 to 2016. The model captures well the general spatial distribution of ice thickness in the CAA region, with very thick sea ice (˜ 4 m and thicker) in the northern CAA, thick sea ice (2.5 to 3 m) in the west-central Parry Channel and M'Clintock Channel, and thin ( < 2 m) ice (in winter months) on the east side of CAA (e.g., eastern Parry Channel, Baffin Island coast) and in the channels in southern areas. Even though the configurations still have resolution limitations in resolving the exact observation sites, simulated ice thickness compares reasonably (seasonal cycle and amplitudes) with weekly Environment and Climate Change Canada (ECCC) New Ice Thickness Program data at first-year landfast ice sites except at the northern sites with high concentration of old ice. At 1/4 to 1/12° scale, model resolution does not play a significant role in the sea ice simulation except to improve local dynamics because of better coastline representation. Sea ice growth is decomposed into thermodynamic and dynamic (including all non-thermodynamic processes in the model) contributions to study the ice thickness evolution. Relatively smaller thermodynamic contribution to ice growth between December and the following April is found in the thick and very thick ice regions, with larger contributions in the thin ice-covered region. No significant trend in winter maximum ice volume is found in the northern CAA and Baffin Bay while a decline (r2 ≈ 0.6, p < 0.01) is simulated in Parry Channel region. The two main contributors (thermodynamic growth and lateral transport) have high interannual variabilities which largely balance each other, so that maximum ice volume can vary interannually by ±12 % in the northern CAA, ±15 % in Parry Channel, and ±9 % in Baffin Bay. Further quantitative evaluation is required.

High Arctic Coasts At Risk - The Impact of Coastal Hazards on Scientific and Community Infrastructure in Svalbard

NASA Astrophysics Data System (ADS)

Strzelecki, M. C.; Pawlowski, L.; Jaskolski, M.; Lim, M.; Zagorski, P.; Long, A. J.; Jensen, M.

2015-12-01

The rapid climate warming being observed in the Svalbard is leading to an increase in human activities in the coastal zone, leading to an increased need for coastal hazard assessment. Present-day Svalbard coastal landscapes are modified by increased degradation of permafrost accelerated sediment supply from deglaciated catchments, and prolonged periods of open-water conditions and wave activity. Since the second half of 20thcentury there is also an observed increase in the number and intensity of storms entering the Arctic particularly in summer months when coastlines are free of protective ice cover. Despite the potential significance of these coastal hazards on the security of scientific (research bases and devices) and community (ports, airports, roads, buildings) infrastructure on Svalbard, relatively little is known on the present-day rate of Svalbard coastal zone changes and how they might impact the nearshore infrastructure in the future. Here we report the results of a project that focused on rates of coastal zone changes in Svalbard and examined the impact of extreme coastal processes on scientific and community infrastructure. The project applied combination of remote sensing and field-based mapping techniques to characterise coastal changes observed in the surroundings of main research stations in Svalbard in Hornsund (PPS), Petuniabukta (AMUPS) and Bellsund (Calypsobyen) as well as a major towns: Longyearbyen, Piramiden, Barentsburg and Svea. Our results document dramatic changes of Svalbard coastal zone under intervals characterised by a warming climate, retreating local ice masses, a shortened winter sea-ice season and melting permafrost. The study confirmed the growing importance of extreme processes in shaping coasts of Svalbard and the impact of these changes on human infrastructure. Our study proposes a risk assessment for a development and protection of infrastructure along the coasts of Svalbard under scenarios of climate change, sea level rise, changes to the frequency of storms entering the region and variations in sea ice extent. The study was funded by the Foundation for Polish Science HOMING PLUS grant no.2013-8/12. Proejct leader is also supported by the National Science Centre Postdoctoral Fellowship (2013/08/S/ST10/00585).

Arctic landfast sea ice

NASA Astrophysics Data System (ADS)

Konig, Christof S.

Landfast ice is sea ice which forms and remains fixed along a coast, where it is attached either to the shore, or held between shoals or grounded icebergs. Landfast ice fundamentally modifies the momentum exchange between atmosphere and ocean, as compared to pack ice. It thus affects the heat and freshwater exchange between air and ocean and impacts on the location of ocean upwelling and downwelling zones. Further, the landfast ice edge is essential for numerous Arctic mammals and Inupiat who depend on them for their subsistence. The current generation of sea ice models is not capable of reproducing certain aspects of landfast ice formation, maintenance, and disintegration even when the spatial resolution would be sufficient to resolve such features. In my work I develop a new ice model that permits the existence of landfast sea ice even in the presence of offshore winds, as is observed in mature. Based on viscous-plastic as well as elastic-viscous-plastic ice dynamics I add tensile strength to the ice rheology and re-derive the equations as well as numerical methods to solve them. Through numerical experiments on simplified domains, the effects of those changes are demonstrated. It is found that the modifications enable landfast ice modeling, as desired. The elastic-viscous-plastic rheology leads to initial velocity fluctuations within the landfast ice that weaken the ice sheet and break it up much faster than theoretically predicted. Solving the viscous-plastic rheology using an implicit numerical method avoids those waves and comes much closer to theoretical predictions. Improvements in landfast ice modeling can only verified in comparison to observed data. I have extracted landfast sea ice data of several decades from several sources to create a landfast sea ice climatology that can be used for that purpose. Statistical analysis of the data shows several factors that significantly influence landfast ice distribution: distance from the coastline, ocean depth, as well as the strength of offshore winds during nine out of the twelve months each year. Additionally, I identify regions where landfast ice appearance has been increasing or decreasing over the observed time span.

Tale of Two Deltas: Permafrost Dynamics on the Colville and Yukon-Kuskokwim Deltas

NASA Astrophysics Data System (ADS)

Jorgenson, T.; Shur, Y.

2016-12-01

Arctic deltas are the predominant coastline in the Arctic and are greatly modified by permafrost aggradation and degradation. In comparing the Colville Delta (CD) along the Beaufort Sea (MAAT -11 °C) with the Yukon-Kuskokwim Delta (YKD) along the Bering Sea (MAAT -1 °C), permafrost characteristics respond to differences in climate, flooding, salinization, and vegetation-soil development. Both deltas have an inner zone dominated by fluvial processes and nonsaline ecosystems, and an outer zone affected by both tidal and fluvial processes and has salt-affected ecosystems. In the CD, closed taliks develop under the deeper channels and surface permafrost starts to form on channel bars where water is <2 m deep. During early floodplain development with active sedimentation, syngenetic permafrost is climate driven, ice-poor, and dominated by pore and lenticular cryostructures. On inactive floodplains, where flooding is infrequent and fine-grained sedimentation is greatly diminished, climate-driven, ecosystem-modified permafrost aggrades upward in response to thickening organics and thinning active layer. Here a 2-m-thick intermediate layer develops that is ice-rich and dominated by reticulate and ataxitic cryostructures. On the oldest abandoned floodplains, permafrost becomes sufficiently ice rich from segregated and wedge ice that thermokarst lakes develop. Large storm surges up to 3 m amsl, such as those in 1963 and 1970, have caused extensive salt killed and ice-wedge degradation. Thus, thermokarst is abundant even at low temperatures. In the YKD, permafrost develops only during late floodplain stages in response to sphagnum accumulation and creates extensive permafrost plateaus that rise 1 m above the floodplain. This ecosystem-driven permafrost is epigenetic, ice-poor, and dominated by pore and lenticular cryostructures. Permafrost develops around existing water bodies, but thermokarst lakes are uncommon. Large storm surges up to 3.5 m amsl, such those in 1974 and 2005, damaged vegetation along the plateaus margins and created shallow thermokarst moats. In response to expected climate warming of 4-6 °C over the next century, permafrost dynamics in the CD should remain similar to current conditions, while in the YKD permafrost likely will be eliminated in the next 30-50 years.

Ecology of tern flight in relation to wind, topography and aerodynamic theory.

PubMed

Hedenström, Anders; Åkesson, Susanne

2016-09-26

Flight is an economical mode of locomotion, because it is both fast and relatively cheap per unit of distance, enabling birds to migrate long distances and obtain food over large areas. The power required to fly follows a U-shaped function in relation to airspeed, from which context dependent 'optimal' flight speeds can be derived. Crosswinds will displace birds away from their intended track unless they make compensatory adjustments of heading and airspeed. We report on flight track measurements in five geometrically similar tern species ranging one magnitude in body mass, from both migration and the breeding season at the island of Öland in the Baltic Sea. When leaving the southern point of Öland, migrating Arctic and common terns made a 60° shift in track direction, probably guided by a distant landmark. Terns adjusted both airspeed and heading in relation to tail and side wind, where coastlines facilitated compensation. Airspeed also depended on ecological context (searching versus not searching for food), and it increased with flock size. Species-specific maximum range speed agreed with predicted speeds from a new aerodynamic theory. Our study shows that the selection of airspeed is a behavioural trait that depended on a complex blend of internal and external factors.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. © 2016 The Author(s).

The Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Garratt, J. R.

1994-05-01

A comprehensive and lucid account of the physics and dynamics of the lowest one to two kilometers of the Earth's atmosphere in direct contact with the Earth's surface, known as the atmospheric boundary layer (ABL). Dr. Garratt emphasizes the application of the ABL problems to numerical modeling of the climate, which makes this book unique among recent texts on the subject. He begins with a brief introduction to the ABL before leading to the development of mean and turbulence equations and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modeling of the ABL is crucially dependent for its realism on the surface boundary conditions, so chapters four and five deal with aerodynamic and energy considerations, with attention given to both dry and wet land surfaces and the sea. The author next treats the structure of the clear-sky, thermally stratified ABL, including the convective and stable cases over homogeneous land, the marine ABL, and the internal boundary layer at the coastline. Chapter seven then extends this discussion to the cloudy ABL. This is particularly relevant to current research because the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic have been identified as key players in the climate system. In the final chapters, Dr. Garratt summarizes the book's material by discussing appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate stimulation.

Ecology of tern flight in relation to wind, topography and aerodynamic theory

PubMed Central

2016-01-01

Flight is an economical mode of locomotion, because it is both fast and relatively cheap per unit of distance, enabling birds to migrate long distances and obtain food over large areas. The power required to fly follows a U-shaped function in relation to airspeed, from which context dependent ‘optimal’ flight speeds can be derived. Crosswinds will displace birds away from their intended track unless they make compensatory adjustments of heading and airspeed. We report on flight track measurements in five geometrically similar tern species ranging one magnitude in body mass, from both migration and the breeding season at the island of Öland in the Baltic Sea. When leaving the southern point of Öland, migrating Arctic and common terns made a 60° shift in track direction, probably guided by a distant landmark. Terns adjusted both airspeed and heading in relation to tail and side wind, where coastlines facilitated compensation. Airspeed also depended on ecological context (searching versus not searching for food), and it increased with flock size. Species-specific maximum range speed agreed with predicted speeds from a new aerodynamic theory. Our study shows that the selection of airspeed is a behavioural trait that depended on a complex blend of internal and external factors. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528786

Identifying extent of technogenous impact on the coastline of Bulgaria based on GIS methodology

NASA Astrophysics Data System (ADS)

Stancheva, Margarita; Palazov, Atanas; Peychev, Veselin; Stanchev, Hristo

2010-05-01

The Bulgarian Black Sea coast is about 412 km long, stretching between cape Sivriburun on the North and Rezovska River mouth on the South. At present, coastal erosion is a common process affecting 61% of the Bulgarian coast, while the sandy beaches comprise at least 30 %. Large number of coast-protection measures has been used to solve and manage the erosion/landslide problems, as most of these methods have involved "hard" stabilisation options such as: solid groins, dikes and seawalls. Design and construction of such protection structures has been increased in particular over the last few decades. About 217 technogenous objects have been indicated as port and coastal defence structures that currently constitute 17 % of the whole Bulgarian coastline. As a result, for a 50-year period (1960-2008) the amount of sediment material, incoming from cliff erosion, river solid discharge and wind-blown material has decreased from 4 979 700 Mg/y to 1 221 300 Mg/y. This in turn has provoked a reduction of sediment supply, sandy beach degradation and even occurrence of new erosion spots. Therefore, the major causes for progressive erosion along the Bulgarian coast could be mostly related to expanding human influence in terms of maritime constructions, dredging works and river corrections. The study is designed to trace the important issues of finding the extent of technogenous impact on the coastal zone of Bulgaria in order to delimitate the areas most influenced by coastline armouring. Topographic maps and GPS field survey data were used for identifying various types of port and coast-protection structures along the coastline. Data processing, mapping and analysis, as well as assessment of technogenous impact on the coastline were methodologically performed with tools of GIS ArcInfo 9.2. To evaluate the extent of anthropogenic influence on the Bulgarian Black Sea coast the coefficient of technogenous impact K was used, which serves for quantitative assessment of the impact of maritime hydraulic structures on the coast. This coefficient represents the ratio between total length of protection structures/objects (groins, moles, seawalls, dikes, navigational channels and permeable bridges) and total length of the coastline. According to this methodology the extent of technogenous impact is considered as minimal at K = 0.0001-0.1; average when K = 0.11-0.5; maximal at K = 0.51-1.0 and extreme if K > 1.0. The coefficient of technogenous impact on the whole Bulgarian coastline was estimated to be K = 0.17, which determines the extent of coastline armouring with port/coast-protection structures as average. Although this value for K of the entire coast could be acceptable, there are large coastal units, distinguished with significant concentration of maritime structures, and these are the largest bays along the Bulgarian shore: Varna Bay, where K reaches to 0.88 and Bourgas Bay with K = 0.26. The main findings from the study reveal an increasing human influence due to coastal defence activities at the Bulgarian Black Sea coast particularly expanded over the last few decades. Instead of soft protection alternatives, the construction of hard stabilisation structures, such as groins, dikes and seawalls, have been assumed as a common solution to prevent the coastline. As a result, the sporadic natural erosion in the near past has turned into human-caused and has become critical at many coastal units. The coefficient K could be used as an indicator for the extent of technogenous impact and would allow quantifying coastline modifications related to maritime structures (port and coast-protection). Keywords: coastal erosion, sediments, human impact, coastal defence, GIS.

Growth of Planted Yellow-Poplar After Vertical Mulching and Fertilization on Eroded Soils

Treesearch

J.B. Baker; B.G. Blackmon

1976-01-01

Fertilization and vertical mulching improved height growth of yellow-poplars planted on eroded soils. A growing demand for hardwood timber accompanied by a diminishing land base has prompted land managers to consider planting hardwoods on marginal sites such as the eroded soils in the Silty Uplands of Arkansas, Louisiana, and Mississippi. Many of these areas were well...

Hypothetical Reentry Thermostructural Performance of Space Shuttle Orbiter With Missing or Eroded Thermal Protection Tiles

NASA Technical Reports Server (NTRS)

Ko, William L.; Gong, Leslie; Quinn, Robert D.

2004-01-01

This report deals with hypothetical reentry thermostructural performance of the Space Shuttle orbiter with missing or eroded thermal protection system (TPS) tiles. The original STS-5 heating (normal transition at 1100 sec) and the modified STS-5 heating (premature transition at 800 sec) were used as reentry heat inputs. The TPS missing or eroded site is assumed to be located at the center or corner (spar-rib juncture) of the lower surface of wing midspan bay 3. For cases of missing TPS tiles, under the original STS-5 heating, the orbiter can afford to lose only one TPS tile at the center or two TPS tiles at the corner (spar-rib juncture) of the lower surface of wing midspan bay 3. Under modified STS-5 heating, the orbiter cannot afford to lose even one TPS tile at the center or at the corner of the lower surface of wing midspan bay 3. For cases of eroded TPS tiles, the aluminum skin temperature rises relatively slowly with the decreasing thickness of the eroded central or corner TPS tile until most of the TPS tile is eroded away, and then increases exponentially toward the missing tile case.

Self-Organized Evolution of Sandy Coastline Shapes: Connections with Shoreline Erosion Problems

NASA Astrophysics Data System (ADS)

Murray, A. B.; Ashton, A.

2002-12-01

Landward movement of the shoreline severely impacts property owners and communities where structures and infrastructure are built near the coast. While sea level rise will increase the average rate of coastal erosion, even a slight gradient in wave-driven alongshore sediment flux will locally overwhelm that effect, causing either shoreline accretion or enhanced erosion. Recent analysis shows that because of the nonlinear relationship between alongshore sediment flux and the angle between deep water wave crests and local shoreline orientation, in some wave climates a straight coastline is unstable (Ashton et al., Nature, 2001). When deep-water waves approach from angles greater than the one that maximizes alongshore flux, in concave-seaward shoreline segments sediment flux will diverge, causing erosion. Similarly, convex regions such as the crests of perturbations on an otherwise straight shoreline will experience accretion; perturbations will grow. When waves approach from smaller angles, the sign of the relationship between shoreline curvature and shoreline change is reversed, but any deviation from a perfectly straight coastline will still result in alongshore-inhomogeneous shoreline change. A numerical model designed to explore the long-term effects of this instability operating over a spatially extended alongshore domain has shown that as perturbations grow to finite amplitude and interact with each other, large-scale coastline structures can emerge. The character of the local and non-local interactions, and the resulting emergent structures, depends on the wave climate. The 100-km scale capes and cuspate forelands that form much of the coast of the Carolinas, USA, provides one possible natural example. Our modeling suggests that on such a shoreline, continued interactions between large-scale structures will cause continued large-scale change in coastline shape. Consequently, some coastline segments will tend to experience accentuated erosion. Communities established in these areas face discouraging future prospects. Attempts can be made to arrest the shoreline retreat on large scales-for example through large beach nourishment projects or policies that allow pervasive hard stabilization (e.g. seawall, jetties) along a coastline segment. However, even if such attempts are successful for a significant period of time, the pinning in place of some parts of an otherwise dynamic system will change the large-scale evolution of the coastline, altering the future erosion/accretion experienced at other, perhaps distant, locations. Simple properties of alongshore sediment transport could also be relevant to alongshore-inhomogeneous shoreline change (including erosion 'hot spots') on shorter time scales and smaller spatial scales. We are comparing predictions arising from the modeling, and from analysis of alongshore transport as a function of shoreline orientation, to recent observations of shoreline change ranging across spatial scales from 100s of meters to 10s of kilometers, and time scales from days to decades (List and Farris, Coastal Sediments,1999; Tebbens et al., PNAS, 2002). Considering that many other processes and factors can also influence shoreline change, initial results show a surprising degree of correlation between observations and predictions.

Ground-based LiDAR application to characterize sea cliff instability processes along a densely populated coastline in Southern Italy

NASA Astrophysics Data System (ADS)

Esposito, Giuseppe; Semaan, Fouad; Salvini, Riccardo; Troise, Claudia; Somma, Renato; Matano, Fabio; Sacchi, Marco

2017-04-01

Sea cliff retreatment along the coastline of the Campi Flegrei volcanic area (Southern Italy) is becoming a threat for public and private structures due to the massive urbanization occurred in the last few decades. In this area, geological features of the outcropping rocks represent one of the most important factors conditioning the sea cliff retreatment. In fact, pyroclastic deposits formed by pumices, scoria, ashes and lapilli are arranged in weakly to moderately welded layers of variable thicknesses, resulting very erodible and prone to landslide processes. Available methods to evaluate topographic changes and retreat rates of sea cliffs include a variety of geomatic techniques, like terrestrial and aerial photogrammetry and LiDAR (Light Detection And Ranging). By means of such techniques, it is in fact possible to obtain high resolution topography of sea cliffs and perform multi-temporal change detection analysis. In this contribution, we present an application of Terrestrial Laser Scanning (TLS or ground-based LiDAR) aimed to identify and quantify instability processes acting along the Torrefumo coastal cliff, in the Campi Flegrei area. Specifically, we acquired a series of 3D point clouds on the years 2013 and 2016, and compared them through a cloud-to-cloud distance computation. Furthermore, a statistical analysis was applied to the change detection results. In this way, an inventory of the cliff failures occurred along the Torrefumo cliff in the 2013-2016 time span was created, as well as the spatial and volumetric distribution of these failures was evaluated. The volumetric analysis shows that large collapses occurred rarely, whereas the spatial analysis shows that the majority of failures occurred in the middle and upper parts of the cliff face. Results also show that both rock fall and surficial erosion processes contribute to the cliff retreatment, acting in turn according to the geological properties of the involved pyroclastic deposits. The presented TLS approach proves to be a cost and time efficient method for characterizing the geomorphic changes involving the sea cliff surfaces over a short-time period (i.e. monthly or yearly). The accuracy of the acquired data allows the characterization of a full range of failures to be located and quantified with a level of detail not reachable using traditional techniques. Results obtained in this research will be used in future applications to assess hazard conditions affecting the anthropic structures built close to the cliff top.

In the Footsteps of Charles Darwin: Patterns of Coastal Subsidence and Uplift Associated with Seamount Subduction, Basal Fore-arc Erosion and Seamount Accretion in Latin America

NASA Astrophysics Data System (ADS)

Fisher, D. M.; Kirby, S. H.; David, S. W.

2004-12-01

In Geological Observations on South America (1846), Charles Darwin described beds of late Cenozoic marine seashells that were uplifted to elevations as much as several hundred meters above some localities on the western coastline of South America and implied that the whole coast was uplifting at geologic time scales. We know now that such evidence is generally restricted to coastal embayments above fore-arc basins where offshore seamounts are colliding with the South American fore arc (e.g., the Juan Fernandez seamount chain, Valpariso Basin and Valpariso Bay). We suggest that the phenomena of basal fore-arc erosion and basin formation and coastal uplift are closely related to effects of seamount subduction. Marine multibeam sonar images and multichannel seismic reflection surveys by others demonstrate that seamounts, although locally cut by normal faults in the outer-rise/near-trench region, initally subduct intact and the primary interaction with the toe of the fore arc is plowing, with material eroded from the fore arc that accumulates above and on the margins of the seamount. Submarine landslides above such regions over-steepened by plowing can lead to coastal embayments far upslope of the plowing. Such plowing interaction can therefore lead to the formation of large forearc basins and coastal embayments such as those at Valpariso, Chile, or narrow corridors of subsidence in the wake of subducting seamounts in Costa Rica. It is also known that the transition between interplate thrust seismicity, representing mechanical coupling between the plates, and aseismic slip occurs at depths of typically 30-60 km and often geographically near coastlines that mark the boundary between outer fore-arc subsidence and inner fore-arc uplift. We suggest that decoupling can occur at the base of seamounts (i.e., the originally sedimented seafloor on which the seamount lavas are laid down) and that such seamounts can be accreted to the fore arc above and lead to coastal uplift. Such basal decoupling is known to occur under active volcanic islands in the open ocean in connection with rifting and gravitational spreading, such as beneath the island of Hawaii. The spatial and temporal patterns of coastal uplift and subsidence on active margins can therefore record the local history of seamount subduction. This conceptual model explains the spatial patterns of offshore subsidence and coastal uplift in Chile and Costa Rica and also has implications for patterns of seismicity along the interplate thrust boundary.

Coastal impacts, adaptation, and vulnerabilities: a technical input to the 2013 National Climate Assessment

USGS Publications Warehouse

Burkett, Virginia; Davidson, Margaret; Burkett, Virginia; Davidson, Margaret

2012-01-01

The coast has long provided communities with a multitude of benefits including an abundance of natural resources that sustain economies, societies, and ecosystems. Coasts provide natural harbors for commerce, trade, and transportation; beaches and shorelines that attract residents and tourists; and wetlands and estuaries that are critical for fisheries and water resources. Coastal ecosystems provide critical functions to cycle and move nutrients, store carbon, detoxify wastes, and purify air and water. These areas also mitigate floods and buffer against coastal storms that bring high winds and salt water inland and erode the shore. Coastal regions are critical in the development, transportation, and processing of oil and natural gas resources and, more recently, are being explored as a source of energy captured from wind and waves. The many benefits and opportunities provided in coastal areas have strengthened our economic reliance on coastal resources. Consequently, the high demands placed on the coastal environment will increase commensurately with human activity. Because 35 U.S. states, commonwealths, and territories have coastlines that border the oceans or Great Lakes, impacts to coastline systems will reverberate through social, economic, and natural systems across the U.S. Impacts on coastal systems are among the most costly and most certain consequences of a warming climate (Nicholls et al., 2007). The warming atmosphere is expected to accelerate sea-level rise as a result of the decline of glaciers and ice sheets and the thermal expansion of sea water. As mean sea level rises, coastal shorelines will retreat and low-lying areas will tend to be inundated more frequently, if not permanently, by the advancing sea. As atmospheric temperature increases and rainfall patterns change, soil moisture and runoff to the coast are likely to be altered. An increase in the intensity of climatic extremes such as storms and heat spells, coupled with other impacts of climate change and the effects of human development, could affect the sustainability of many existing coastal communities and natural resources. This report, one of a series of technical inputs for the third NCA conducted under the auspices of the U.S. Global Change Research Program, examines the known effects and relationships of climate change variables on the coasts of the U.S. It describes the impacts on natural and human systems, including several major sectors of the U.S. economy, and the progress and challenges to planning and implementing adaptation options. Below we present the key findings from each chapter of the report, beginning with the following key findings from Chapter 1: Introduction and Context.

Patterns and Rates of Historical Shoreline Change along the New England and Mid-Atlantic Coasts

NASA Astrophysics Data System (ADS)

Kratzmann, M. G.; Hapke, C. J.; Himmelstoss, E. A.; List, J. H.; Thieler, E. R.

2010-12-01

The U.S. Geological Survey is analyzing historical shoreline changes along open-ocean shores of the conterminous United States and parts of Hawaii, Alaska and the Great Lakes to calculate trends and rates of shoreline movement. This accurate and detailed coastal change information is necessary as growing coastal communities and infrastructure are threatened by erosion. Repeatable analytical methods were developed for shoreline movement calculations to facilitate periodic updates of coastal change in a systematic and internally consistent manner. The U.S. New England and Mid-Atlantic coasts from Maine to Virginia are the most recent to be completed in the National Assessment of Shoreline Change project. Shorelines from the 1800s through 2007 were derived from historical maps, orthophotos, and airborne lidar (1997-2007). All shoreline change rates are calculated using the Digital Shoreline Analysis System (DSAS) developed by the U.S. Geological Survey. Long-term rates of change are calculated using linear regression through all available shorelines (n = 4 to 12) for the full period of record (100-150 years). Short-term rates of change are calculated for the most recent 25-30 years, using the end-point method. Shoreline change rates were calculated for 78% of the 1360 km of coast in the study area. Complete coverage is lacking due to data gaps, as well as locations (rocky coastlines, large embayments, and beaches) where robust data are unavailable. The average rates of shoreline change for New England and the Mid-Atlantic are erosional, with higher erosion rates observed in the long-term than in the short-term. The average rates of long- and short-term shoreline change in New England (Maine, New Hampshire, Massachusetts, Rhode Island) are -0.4 m/yr ± 0.1 m/yr and -0.2 ± 0.09 m/yr, respectively. The average long-term rate in the Mid-Atlantic (New York, New Jersey, Delaware, Maryland, Virginia) is -0.6 ± 0.1 m/yr and the short-term rate of change is -0.3 ± 0.1 m/yr. In the Mid-Atlantic, there is a more pronounced difference in the percentage of erosional transects in the long-term (67%) than the short-term (54%), unlike the similar percentages of erosional transects in the long- (71%) and short-term (70%) within New England. However, the percentage of coastline eroding at higher rates (more than -3 m/yr) is greater in the short-term for both New England and the Mid-Atlantic, suggesting an increase in erosional hazards.

Proceedings of the Conference Arctic '85; Civil Engineering in the Artic offshore

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, F.L.; Machemehl, J.L.

1985-01-01

Topics of the 1985 Conference included: Arctic construction, Arctic foundation, Arctic structures, and ocean effects. Arctic terminals and coastal offshore bases, protecting the Arctic environment, and probabilistic methods in Arctic offshore engineering were also discussed. Ice mechanics, marine pipelines in the Arctic, and the role of universities in training civil engineers for Arctic offshore development were highlighted. Sessions on remote sensing, surveying, and mapping were included, and offshore installations in the Bering Sea were discussed. Another topic of discussion was research in Civil Engineering for development of the Arctic offshore. The overall thrust of the conference was the application ofmore » Arctic offshore engineering principles and research in the field of oil and gas exploration and exploitation activity.« less

Effects of vegetation and fecal pellets on the erodibility of cohesive sediments: Ganghwa tidal flat, west coast of Korea.

PubMed

Ha, Ho Kyung; Ha, Hun Jun; Seo, Jun Young; Choi, Sun Min

2018-06-04

Although the Korean tidal flats in the Yellow Sea have been highlighted as a typical macrotidal system, so far, there have been no measurements of the sediment erodibility and critical shear stress for erosion (τ ce ). Using the Gust erosion microcosm system, a series of field experiments has been conducted in the Ganghwa tidal flat to investigate quantitatively the effects of biogenic materials on the erodibility of intertidal cohesive sediments. Four representative sediment cores with different surficial conditions were analyzed to estimate the τ ce and eroded mass. Results show that τ ce of the "free" sediment bed not covered by any biogenic material on the Ganghwa tidal flat was in the range of 0.1-0.2 Pa, whereas the sediment bed partially covered by vegetation (Phragmites communis) or fecal pellets had enhanced τ ce up to 0.45-0.6 Pa. The physical presence of vegetation or fecal pellets contributed to protection of the sediment bed by blocking the turbulent energy. An inverse relationship between the organic matter included in the eroded mass and the applied shear stress was observed. This suggests that the organic matter enriched in a near-bed fluff layer is highly erodible, and the organic matter within the underlying sediment layer becomes depleted and less erodible with depth. Our study underlines the role of biogenic material in stabilizing the benthic sediment bed in the intertidal zone. Copyright © 2018 Elsevier Ltd. All rights reserved.

The StreamCat Dataset: Accumulated Attributes for NHDPlusV2 Catchments (Version 2.1) for the Conterminous United States: Soil Erodibility (KFFACT)

EPA Pesticide Factsheets

This dataset represents the adjusted soil erodibility factor within individual, local NHDPlusV2 catchments and upstream, contributing watersheds. Attributes of the landscape layer were calculated for every local NHDPlusV2 catchment and accumulated to provide watershed-level metrics. (See Supplementary Info for Glossary of Terms) The STATSGO Layer table specifies two soil erodibility factors for each component layer, KFFACT and KFACT. The STATSGO documentation describes KFFACT as a soil erodibility factor which quanitifies the susceptibility of soil particles to detachment and movement by water. This factor is used in the Universal Soil Loss Equation to caluculate soil loss by water. KFACT is described as a soil erodibility factor which is adjusted for the effect of rock fragments. The average value of each of these soil erodibility factors was determined for the top (surface) layer for each map unit of each state.The base-flow index (BFI) grid for the conterminous United States was developed to estimate (1) BFI values for ungaged streams, and (2) ground-water recharge throughout the conterminous United States (see Data Source). Estimates of BFI values at ungaged streams and BFI-based ground-water recharge estimates are useful for interpreting relations between land use and water quality in surface and ground water. The soil erodibility factor was summarized by local catchment and by watershed to produce local catchment-level and watershed-level metri

Soils as sediment: does aggregation skew slope scale SOC balances?

NASA Astrophysics Data System (ADS)

Hu, Yaxian; Fister, Wolfgang; Kuhn, Nikolaus

2014-05-01

The net effect of soil erosion as a source or sink of CO2 in global carbon cycling has been the subject of a heated debate. On one hand, erosion exposes the previously encapsulated soil organic carbon (SOC), which may accelerate the mineralization of eroded SOC. On the other hand, deposition limits the decomposition of SOC upon burial, while incorporation of biomass at eroding sites replaces the lost SOC. So far, effects of erosion on CO2 emissions have largely been assessed by comparing SOC stocks at eroding and depositional sites. The underlying assumption for this approach is a non-selective transport of eroded SOC across a landscape. However, several recent publications showed both an at least temporary on-site enrichment of SOC in sediment as well as a preferential deposition of sediment particles with SOC concentrations that differed from the soil SOC. As a consequence, balances between eroding and depositional sites may over- or underestimate mineralization of eroded SOC during transport. Two Luvisols, from the villages of Möhlin and Movelier in northwest Switzerland, were used in this study. They have different mineral grain size distribution, organic carbon concentration and aggregate stability. Based on the concept of Equivalent Quartz Size (EQS), the eroded sediments were fractionated by a settling tube apparatus into six different size classes, according to their settling velocities and likely transport distances. According to the model developed by Starr et al., 2000, the likely transport distances of six EQS classes were grouped into three likely fates: deposited across landscapes, possibly transferred into rivers, and likely transferred into rivers. Respiration rates of the fractionated sediments were measured by gas chromatograph for 50 days. Our results show that 1) due to aggregation, 60% of the Möhlin eroded fractions and 82% of the Movelier fractions would be re-deposited in the terrestrial system, which strongly contrasts with their grain size distribution; 2) 63% of eroded SOC for the Möhlin soil and 83% for the Movelier soil would be re-deposited in the terrestrial system rather than transferred into the aquatic system. This is much greater than the high concentration of SOC in grain size fraction <32 µm would suggest; 3) the SOC re-deposited in the terrestrial system is more likely to be mineralized than the SOC in fine particles which would be transferred into the aquatic system. Our observations indicate that 1) aggregation reduces the likely transport distances of eroded SOC, and thus decreases the likelihood of eroded SOC to be transferred from eroding hill-slopes to the aquatic system; 2) the re-deposited SOC in the terrestrial system is more likely to be mineralized than the SOC in fine particles that could be transferred into the aquatic system. These findings highlight a potentially higher contribution of erosion to atmospheric CO2 than anticipated by estimating source for sink transfer without considering the effects of aggregation.

76 FR 330 - Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-04

... USFWS initiated a capture-based research program starting in 2008 on the sea ice off the Chukchi Sea coastline. Captures occur on the sea ice up to 100 mi (161 km) offshore of the Alaskan coastline between Shishmaref and Cape Lisburne (see Figure 1 in the USFWS' application). Take of ice seals may occur when the...

New Insights About Large-Scale Delta Morphodynamics from a Coupled Model of Fluvial-Coastal Processes

NASA Astrophysics Data System (ADS)

Murray, A. B.; Ratliff, K. M.; Hutton, E.

2017-12-01

We use a newly developed delta model to explore the combined effects of sea-level rise (SLR) and variable wave influence on delta morphology, avulsion behavior, and autogenic sediment flux variability. Using the Community Surface Dynamics Modeling System framework and tools, we couple the River Avulsion and Floodplain Evolution Model (RAFEM) to the Coastline Evolution Model (CEM). RAFEM models the fluvial processes, including river profile evolution, floodplain deposition, and avulsions. CEM uses gradients in alongshore sediment transport to distribute the fluvial sediment along the coastline. A suite of recent experiments using the coupled model and the Dakota software toolkit lead to several new insights: 1) A preferential avulsion location (which scales with the backwater length) can arise for geometric reasons that are independent of the recently suggested importance of alternation between flood and inter-flood periods. 2) The angular distribution of waves, as well as the wave height, affect the avulsion timescale. Previous work suggested that the time between avulsions will increase with greater wave influence, and we find that this is true for an angular mix of waves that tends to smooth a fairly straight coastline (coastline diffusion), where river mouth progradation is slowed and avulsions are delayed. However, if the angular distribution of waves leads to locally smooth shorelines but large amplitude coastline features (anti-diffusive coastline evolution), then avulsion timescales are barely affected, even when wave influence is high. 3) Increasing SLR rates are expected to cause more frequent avulsions, and it does in laboratory deltas. Unexpectedly, we find that this is not the case for the river-dominated deltas in our coupled model, in which SLR-related transgression effectively decreases progradation, offsetting base-level-rise effects. This finding raises potentially important questions about the geometric differences between prototypical and laboratory deltas that have not previously been addressed. 4) The magnitude and timescale of autogenic variability in the sediment flux at the river mouth depends on the SLR rate (for some wave climates), wave characteristics, and the how high the river channel must be super-elevated relative to the floodplain in order to trigger an avulsion.

Distribution of basic sediments (bedload transport) on changes in coastal coastline Donggala, Central Sulawesi Province, Indonesia

NASA Astrophysics Data System (ADS)

Amiruddin

2018-03-01

This study entitled "Distribution of Bedload Transport Against Coastline Changes in Donggala Coast", the formulation of the problem (1) how much of the estimated bedload transport in Donggala Bodies; (2) where were the location of erosion and sedimentation strong point based on the estimation of bed load transport; (3) the extent to which the prediction of shoreline change rate of transport of sediments in coastal areas Donggala. This study aims to: (1) the calculation of estimated bed load transport in Donggala waters; (2) determining the location of the point of erosion and sedimentation strong basis of estimated bedload transport; (3) the prediction of shoreline change rate of transport of sediments in coastal areas Donggala.The survey method used in this research to collect primary data include: (1) decision point waypoint coordinates of each location of measurement; (2) measurement of height, period and direction of the waves; (3) a large measurement of sediment transport; (4) The angle measurement coastline, angle of attack and wave direction, and secondary data include: (1) information from the public; (2) the physical condition data field. The results showed that: (1) general estimate sediment transport base in each location data collection is varied. This is due to the different points of the coastline as well as the angle of attack of the shoreline waters broke Donggala; (2) strong abrasion at the study site occurs at the point Ts4 (622.75 m3/yr) and TS11 (755.25 m3/yr) located in the Village Tosale and point Tw7 and Tw17 (649.25 m3/yr) in Village of Towale. As for the strong sedimentation occurs at the point Ts3 (450.50 m3/yr) located in the Village Tosale and Tg3 point (357.75 m3/yr) located in the Village Tolonggano; (3) of the predicted outcome coastline changes based on the input data estimate sediment transport, beaches and waves parameters is seen that the changes in the location prophyl coastline tends toward research into or undergo a process of abrasion.

Settling Velocity Specific SOC Distribution along Hillslopes - A field investigation in Denmark

NASA Astrophysics Data System (ADS)

Kuhn, N. J.; Hu, Y.

2015-12-01

The net effects of soil erosion by water, as a sink or source of atmospheric CO2, are decisively affected by the spatial re-distribution and stability of eroded soil organic carbon (SOC). The deposition position of eroded SOC, into terrestrial or aquatic systems, is actually decided by the transport distances of soil fractions where the SOC is stored. In theory, the transport distances of aggregated soil fractions are related to their settling velocities under given layer conditions. Yet, little field investigation has been conducted to examine the actual movement of eroded soil fractions along hillslopes, let alone the re-distribution pattern of functional SOC fractions. Eroding sandy soils and sediment were sampled after a series of rainfall events from different topographic positions along a slope on a freshly seeded cropland in Jutland, Denmark. All the soil samples from difference topographic positions along the slope were fractionated into five settling classes using a settling tube apparatus. The SOC content, 13C signature, and C:N ratios of all settling fractions were measured. Our results show that: 1) the spatial distribution of soil settling classes along the slope clearly shows a coarsening effect at the deposition area immediately below the eroding slope, followed by a fining trend on the deposition area at the slope tail. This proves the validity of the conceptual model in Starr et al. 2000 to predict SOC redistribution patterns along eroding hillslopes. 2) The isotopically enriched 13C on the slope back suggests greater decomposition rates possibly experienced by eroded SOC during transport, while the pronounced respiration rates at the slope tail indicate a great potential of CO2 emissions after deposition. Overall, our results illustrate that immediate deposition of fast settling soil fractions, and the thus induced preferential deposition of SOC at foot slope and potential CO2 emissions during transport, must be appropriately accounted for in current soil carbon balances. To achieve this, a SOC erodibility parameter based on the actual settling velocity distribution of eroded fractions (aggregated or not aggregated) is urgently needed to better parameterize soil erosion models with respect to SOC spatial redistribution.

Study of glyphosate transport through suspended particulate matter

NASA Astrophysics Data System (ADS)

Amiot, Audrey; Landry, David; Jadas-Hécart, Alain; La Jeunesse, Isabelle; Sourice, Stéphane; Ballouche, Aziz

2014-05-01

The results have been produced in a project aiming to improve the water quality of the Layon localy supported by stakeholders involved in the implementation of the Water Framework Directive as the SAGE-Layon Aubance. The study site is a small vineyard catchment (2.2 ha) of the Loire Valley. The slopes of the study site are between 8 and 40% resulting in strong erosive episodes during rainy event. The main objective is to understand the transfer of pesticide residues to stream. Preliminary results have shown glyphosate can be found with high concentrations during runoff. However this study was realized only in the dissolved phase. The objective is now to understand the glyphosate transport driven by SPM. The methodology developed has been (i) characterization and production of the erodible water fraction from soils aggregates; (ii) achievement of the adsorption of glyphosate on these erodible materials to compare this results with adsorption on soil sieved to 2 mm, (iii) achievement of the desorption of glyphosate on these erodible materials. Measurements have been performed on soil samples distinguishing weed or grassed soils. Soils are sieved to 2 mm or between 2 and 5 mm (to produce the erodible water fraction). Both fractions are then used to glyphosate sorption and desorption. The erodible fraction was produce with a wet sieving machine (eijkelkampt Method Kemper and Rosenau, 1986), using sieve porosity of 250 microns. The fraction obtained at 250 microns is considered to be the erodible water fraction and is used to study the adsorption and desorption of glyphosate. Kinetics has been first carried out then the isotherm to obtain the value of Kd. A ratio soil/solution of 1/5 was used. Successive desorption's method was chosen with a stirring time of 20 min, centrifugation at 6000 g and the supernatant in each desorption of 20 min is analyzed. This step is repeated 25 times. The main results of the study are: (i) adsorption of glyphosate is rapid and almost complete (95% in 2 min). (ii) Kd obtained on the erodible fraction are two times higher than on 2 mm sieved soils. (iii) Desorption showed that glyphosate is desorbed from the erodible fraction at 40% after 25 desorptions. The aim of this study was to show the potential transport of glyphosate through suspended particulate matter. The adsorption on the erodible fraction argued to a significant transport potential of glyphosate on this fraction. The desorption of glyphosate from the erodible water fraction have revealed that the adsorption of glyphosate is reversible but it is much slower. These results demonstrate that glyphosate may be stored on the erodible fraction and be transported by these fractions. Keywords: Adsorption, Desorption, Glyphosate, Suspended Solids, Erosion.

Categorizing the severity of paralytic shellfish poisoning outbreaks in the Gulf of Maine for forecasting and management

NASA Astrophysics Data System (ADS)

Kleindinst, Judith L.; Anderson, Donald M.; McGillicuddy, Dennis J.; Stumpf, Richard P.; Fisher, Kathleen M.; Couture, Darcie A.; Michael Hickey, J.; Nash, Christopher

2014-05-01

Development of forecasting systems for harmful algal blooms (HABs) has been a long-standing research and management goal. Significant progress has been made in the Gulf of Maine, where seasonal bloom forecasts are now being issued annually using Alexandrium fundyense cyst abundance maps and a population dynamics model developed for that organism. Thus far, these forecasts have used terms such as “significant”, “moderately large” or “moderate” to convey the extent of forecasted paralytic shellfish poisoning (PSP) outbreaks. In this study, historical shellfish harvesting closure data along the coast of the Gulf of Maine were used to derive a series of bloom severity levels that are analogous to those used to define major storms like hurricanes or tornados. Thirty-four years of PSP-related shellfish closure data for Maine, Massachusetts and New Hampshire were collected and mapped to depict the extent of coastline closure in each year. Due to fractal considerations, different methods were explored for measuring length of coastline closed. Ultimately, a simple procedure was developed using arbitrary straight-line segments to represent specific sections of the coastline. This method was consistently applied to each year’s PSP toxicity closure map to calculate the total length of coastline closed. Maps were then clustered together statistically to yield distinct groups of years with similar characteristics. A series of categories or levels was defined (“Level 1: Limited”, “Level 2: Moderate”, and “Level 3: Extensive”) each with an associated range of expected coastline closed, which can now be used instead of vague descriptors in future forecasts. This will provide scientifically consistent and simply defined information to the public as well as resource managers who make decisions on the basis of the forecasts.

Categorizing the severity of paralytic shellfish poisoning outbreaks in the Gulf of Maine for forecasting and management

PubMed Central

Kleindinst, Judith L.; Anderson, Donald M.; McGillicuddy, Dennis J.; Stumpf, Richard P.; Fisher, Kathleen M.; Couture, Darcie A.; Hickey, J. Michael; Nash, Christopher

2014-01-01

Development of forecasting systems for harmful algal blooms (HABs) has been a long-standing research and management goal. Significant progress has been made in the Gulf of Maine, where seasonal bloom forecasts are now being issued annually using Alexandrium fundyense cyst abundance maps and a population dynamics model developed for that organism. Thus far, these forecasts have used terms such as “significant”, “moderately large” or “moderate” to convey the extent of forecasted paralytic shellfish poisoning (PSP) outbreaks. In this study, historical shellfish harvesting closure data along the coast of the Gulf of Maine were used to derive a series of bloom severity levels that are analogous to those used to define major storms like hurricanes or tornados. Thirty-four years of PSP-related shellfish closure data for Maine, Massachusetts and New Hampshire were collected and mapped to depict the extent of coastline closure in each year. Due to fractal considerations, different methods were explored for measuring length of coastline closed. Ultimately, a simple procedure was developed using arbitrary straight-line segments to represent specific sections of the coastline. This method was consistently applied to each year’s PSP toxicity closure map to calculate the total length of coastline closed. Maps were then clustered together statistically to yield distinct groups of years with similar characteristics. A series of categories or levels was defined (“Level 1: Limited”, “Level 2: Moderate”, and “Level 3: Extensive”) each with an associated range of expected coastline closed, which can now be used instead of vague descriptors in future forecasts. This will provide scientifically consistent and simply defined information to the public as well as resource managers who make decisions on the basis of the forecasts. PMID:25076815

Image navigation and registration for the geostationary lightning mapper (GLM)

NASA Astrophysics Data System (ADS)

van Bezooijen, Roel W. H.; Demroff, Howard; Burton, Gregory; Chu, Donald; Yang, Shu S.

2016-10-01

The Geostationary Lightning Mappers (GLM) for the Geostationary Operational Environmental Satellite (GOES) GOES-R series will, for the first time, provide hemispherical lightning information 24 hours a day from longitudes of 75 and 137 degrees west. The first GLM of a series of four is planned for launch in November, 2016. Observation of lightning patterns by GLM holds promise to improve tornado warning lead times to greater than 20 minutes while halving the present false alarm rates. In addition, GLM will improve airline traffic flow management, and provide climatology data allowing us to understand the Earth's evolving climate. The paper describes the method used for translating the pixel position of a lightning event to its corresponding geodetic longitude and latitude, using the J2000 attitude of the GLM mount frame reported by the spacecraft, the position of the spacecraft, and the alignment of the GLM coordinate frame relative to its mount frame. Because the latter alignment will experience seasonal variation, this alignment is determined daily using GLM background images collected over the previous 7 days. The process involves identification of coastlines in the background images and determination of the alignment change necessary to match the detected coastline with the coastline predicted using the GSHHS database. Registration is achieved using a variation of the Lucas-Kanade algorithm where we added a dither and average technique to improve performance significantly. An innovative water mask technique was conceived to enable self-contained detection of clear coastline sections usable for registration. Extensive simulations using accurate visible images from GOES13 and GOES15 have been used to demonstrate the performance of the coastline registration method, the results of which are presented in the paper.

Earth Observations

NASA Image and Video Library

2011-06-02

ISS028-E-006687 (2 June 2011) --- Estuaries on the northwestern coast of Madagascar are featured in this image photographed by an Expedition 28 crew member on the International Space Station. Regions where fresh water flowing in rivers and salt water from the seas and oceans mix are called estuaries, and they are among the most biologically productive ecosystems on Earth. This photograph highlights two estuaries located along the northwestern coastline of the island of Madagascar. The Mozambique Channel (top) separates Madagascar from the southeastern coast of Africa. Bombetoka Bay (upper left) is fed by the Betsiboka River and is a frequent subject of astronaut photography due to its striking red floodplain sediments. Mahajamba Bay (right) is fed by several rivers including the Mahajamba and Sofia Rivers; like the Betsiboka, the floodplains of these rivers also contain reddish sediments eroded from their basins upstream. The brackish (mix of fresh and salty water) conditions found in most estuaries host unique plant and animal species adapted to live in such environments. Mangroves in particular are a common plant species found in and around Madagascar estuaries, and Bombetoka Bay contains some of the largest remaining stands. Estuaries also host abundant fish and shellfish species ? many of which need access to freshwater for a portion of their life cycles ? and these in turn support local and migratory bird species that prey on them. However, human activities such as urban development, overfishing, and increased sediment loading from erosion of upriver highlands threaten the ecosystem health of the estuaries. In particular, the silt deposits in Bombetoka Bay at the mouth of the Betsiboka River have been filling in the bay.

Impact of coastal processes on resource development with an example from Icy Bay, Alaska

USGS Publications Warehouse

Molnia, Bruce F.

1978-01-01

The coastline of Alaska is dynamic and continually readjusting to changes in the many processes that operate in the coastal zone. Because of this dynamic nature, special consideration must be made in planning for development, and. caution must be exercised in site selection for facilities to be emplaced in the coastal zone. All types of coastal processes from continuously active normal processes to the low frequency-high intensity rare event must be considered. Site-specific evaluation-s considering the broad range of possible processes must precede initiation of development. An example of the relation between coastal processes and a proposed resource treatment facility is presented for Icy Bay, Alaska. Icy Bay is the only sheltered bay near many of the offshore tracts leased for petroleum exploration in the 1976 northern Gulf of Alaska OCS (Outer Continental Shelf) lease sale. Consequently, it has been selected as a primary onshore staging site for the support of offshore exploration and development. The environment of Icy Bay has many potentially hazardous features, including a submarine moraine at the bay mouth and actively calving glaciers at the bay's head which produce many icebergs. But most significant from the point of view of locating onshore facilities and pipeline corridors are the high rates of shoreline erosion and sediment deposition. If pipelines or any onshore staging facilities are to be placed in the coastal areas of Icy Bay, then the dynamic changes in shoreline position must be considered so that man-made structures will not be eroded away or be silted in before the completion of development.

Spatial and temporal distribution of mercury and methylmercury in bivalves from the French coastline.

PubMed

Briant, N; Chouvelon, T; Martinez, L; Brach-Papa, C; Chiffoleau, J F; Savoye, N; Sonke, J; Knoery, J

2017-01-30

Marine mercury (Hg) concentrations have been monitored in the French coastline for the last half a century using bivalves. The analyses presented in this study concerned 192 samples of bivalves (mussels: Mytilus edulis and Mytilus galloprovincialis and oysters: Crassostrea gigas and Isognomon alatus) from 77 sampling stations along the French coast and in the French Antilles sea. The goals of this study were to assess MeHg levels in various common bivalves from French coastline, and to identify possible geographic, taxonomic or temporal variations of concentrations. We show that the evolution of methylmercury (MeHg) concentrations covary with total mercury (HgT) concentrations. Moreover, in most of the study sites, HgT concentrations have not decreased since 1987, despite regulations to decrease or ban mercury used for anthropic activities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chapter 9: The rock coast of the USA

USGS Publications Warehouse

Hapke, Cheryl J.; Adams, Peter N.; Allan, Jonathan; Ashton, Andrew; Griggs, Gary B.; Hampton, Monty A.; Kelly, Joseph; Young, Adam P.

2014-01-01

The coastline of the USA is vast and comprises a variety of landform types including barrier islands, mainland beaches, soft bluffed coastlines and hard rocky coasts. The majority of the bluffed and rocky coasts are found in the northeastern part of the country (New England) and along the Pacific coast. Rocky and bluffed landform types are commonly interspersed along the coastline and occur as a result of relative lowering of sea level from tectonic or isostatic forcing, which can occur on timescales ranging from instantaneous to millenia. Recent research on sea cliffs in the contiguous USA has focused on a broad range of topics from documenting erosion rates to identifying processes and controls on morphology to prediction modelling. This chapter provides a detailed synthesis of recent and seminal research on rocky coast geomorphology along open-ocean coasts of the continental United States (USA).

Simulating eroded soil organic carbon with the SWAT-C model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Xuesong

The soil erosion and associated lateral movement of eroded carbon (C) have been identified as a possible mechanism explaining the elusive terrestrial C sink of ca. 1.7-2.6 PgC yr(-1). Here we evaluated the SWAT-C model for simulating long-term soil erosion and associated eroded C yields. Our method couples the CENTURY carbon cycling processes with a Modified Universal Soil Loss Equation (MUSLE) to estimate C losses associated with soil erosion. The results show that SWAT-C is able to simulate well long-term average eroded C yields, as well as correctly estimate the relative magnitude of eroded C yields by crop rotations. Wemore » also evaluated three methods of calculating C enrichment ratio in mobilized sediments, and found that errors associated with enrichment ratio estimation represent a significant uncertainty in SWAT-C simulations. Furthermore, we discussed limitations and future development directions for SWAT-C to advance C cycling modeling and assessment.« less

Elastic wave generated by granular impact on rough and erodible surfaces

NASA Astrophysics Data System (ADS)

Bachelet, Vincent; Mangeney, Anne; de Rosny, Julien; Toussaint, Renaud; Farin, Maxime

2018-01-01

The elastic waves generated by impactors hitting rough and erodible surfaces are studied. For this purpose, beads of variable materials, diameters, and velocities are dropped on (i) a smooth PMMA plate, (ii) stuck glass beads on the PMMA plate to create roughness, and (iii) the rough plate covered with layers of free particles to investigate erodible beds. The Hertz model validity to describe impacts on a smooth surface is confirmed. For rough and erodible surfaces, an empirical scaling law that relates the elastic energy to the radius Rb and normal velocity Vz of the impactor is deduced from experimental data. In addition, the radiated elastic energy is found to decrease exponentially with respect to the bed thickness. Lastly, we show that the variability of the elastic energy among shocks increases from some percents to 70% between smooth and erodible surfaces. This work is a first step to better quantify seismic emissions of rock impacts in natural environment, in particular on unconsolidated soils.

Estimate Soil Erodibility Factors Distribution for Maioli Block

NASA Astrophysics Data System (ADS)

Lee, Wen-Ying

2014-05-01

The natural conditions in Taiwan are poor. Because of the steep slopes, rushing river and fragile geology, soil erosion turn into a serious problem. Not only undermine the sloping landscape, but also created sediment disaster like that reservoir sedimentation, river obstruction…etc. Therefore, predict and control the amount of soil erosion has become an important research topic. Soil erodibility factor (K) is a quantitative index of distinguish the ability of soil to resist the erosion separation and handling. Taiwan soil erodibility factors have been calculated 280 soil samples' erodibility factors by Wann and Huang (1989) use the Wischmeier and Smith nomorgraph. 221 samples were collected at the Maioli block in Miaoli. The coordinates of every sample point and the land use situations were recorded. The physical properties were analyzed for each sample. Three estimation methods, consist of Kriging, Inverse Distance Weighted (IDW) and Spline, were applied to estimate soil erodibility factors distribution for Maioli block by using 181 points data, and the remaining 40 points for the validation. Then, the SPSS regression analysis was used to comparison of the accuracy of the training data and validation data by three different methods. Then, the best method can be determined. In the future, we can used this method to predict the soil erodibility factors in other areas.

Cytochrome P450 1A induction in gudgeon Gobio gobio : Laboratory and Field Studies.

PubMed

Flammarion, P

1999-01-01

The induction of cytochrome P450 1A was studied in gudgeon (Gobio gobio), a common European cyprinid, using both farm-raised and field-caught fish. The effects of sex, reproductive status and past exposure to xenobiotics were assessed. When exposed to beta-naphthoflavone (bNF), reared gudgeon showed a dose-dependent increase of EROD activity with a plateau observed at doses from 20 mg kg-1 (females) and 5 mg kg-1 (males). The sexual difference in EROD activity was related to the gonadosomatic index (GSI) of the female whatever the level of induction. Dose and sex effects were confirmed by the immunodetection of CYP1A protein. More than 1 month was necessary for EROD activity to decrease to baseline levels. A second bNF injection after 32 days gave similar levels of induction, suggesting that EROD induction by bNF was not impaired by a pretreatment. Wild fish were brought from two sites in the Rhone river basin: a low contaminated site (Ain) and a highly contaminated site (Rhone). Wild gudgeon were highly induced by bNF in laboratory conditions, except males from the Rhone site which exhibited EROD levels as high as the EROD plateau found in laboratory conditions. A 2- month depuration period in clean water was necessary for EROD activity in wild gudgeon to decrease to baseline levels. These results provide better knowledge of the main factors of modulation of the induction in gudgeon as well as on the influence of the history of exposure to inducers.

Impinging Jets and the Erodibility of Cohesive Sediment

NASA Astrophysics Data System (ADS)

Karamigolbaghi, M.; Bennett, S. J.; Ghaneeizad, S. M.; Atkinson, J. F.

2016-12-01

Defining the erodibility of cohesive sediment remains a critical challenge in Earth surface systems. The primary geomorphic law used in such applications relates erosion rate to an erodibility coefficient and an excess shear stress term. To assess erodibility, an inverse modeling approach can be adopted, wherein a known stress is applied to the cohesive sediment, and the erodibility parameters can be deduced through observation of erosion as a function of time. An impinging jet, as used in the jet erosion test, would appear to be an ideal flow (stress) source for erosion assessment. Recent work, however, has demonstrated that jet hydrodynamics can depart significantly from ideal flow conditions when employed for in situ erosion assessment. Here we will review jet theory and the use of jets for assessing the erodibility of cohesive sediment. Our results show that (1) flow confinement and the generation of secondary circulation can significantly change bed shear stress near and downstream of impingement, (2) the evolving scour hole shape, as conditioned by material characteristics and the erosion process, can significantly alter jet hydrodynamics and bed shear stress magnitudes and distributions near and downstream of impingement, and (3) incidental variations in material characteristics in carefully-executed, long-lived experiments can produce markedly different scour hole shapes and derived erodibility indices. Examples from experimental, numerical, and field observations will be used to illustrate these hydrodynamic and material effects on observed and predicted erosion rates. Because such effects are difficult to anticipate, the uncertainty of in situ cohesive sediment assessments using impinging jets can be quite large.

Sea cliff erosion in the eastern part of the North Aegean coastline, Northern Greece.

PubMed

Xeidakis, George S; Delimani, P K; Skias, S G

2006-01-01

The coastal zone is an area where many human activities are taking place. Erosion of the coast obstructs, in various ways, these activities creating occasionally serious socioeconomic and environmental problems. In this paper the coastal erosion problems encountered in the eastern Greek part of the North Aegean Sea Coast, a stretch of about 51 km long adjacent to the city of Alexandroupolis, are discussed. Given the observed type and location of erosion and other sea-action phenomena, the coast under study is divided in two parts/stretches. The western stretch, where the city of Alexandroupolis is presently extending, presents, mainly, cliff erosion problems and retreat of the coastline, very serious in some sections; whereas, the eastern stretch (to the east of the city) exhibits deposition and progression seawards due to the abundance of sediments supplied by Evros river delta. A classification of the coastline according to its relief, geologic material, erosion characteristics and rate, slope failure phenomena as well as the wave energy potential, is presented together with suggestions for case-appropriate mitigation and protection measures regarding the coastal erosion problems. The paper is focusing on the cliff erosion phenomena, since varying in height coastal cliffs made of soft rocks, cover the major part of the investigated coastline (western stretch).

Combining airborne thermal infrared images, radium isotopes and radon to study Submarine Groundwater Discharge along the French Mediterranean coastline (Côte Bleue)}

NASA Astrophysics Data System (ADS)

Bejannin, Simon; Tamborski, Joseph; Souhaut, Marc; Radakovitch, Olivier; Claude, Christelle; Stieglitz, Thomas; Crispi, Olivier; Pujo-Pay, Mireille; Conan, Pascal; Caparros, Jocelyne; Heimburger, Lars-Eric; Petrova, Macha; Le Roy, Emilie; Lacan, François; van Beek, Pieter

2017-04-01

Submarine Groundwater Discharge (SGD) is now recognized as an important vector for many chemical elements that may impact the quality of the coastal environment and marine ecosystems. Although these fluxes have been investigated in many places of the world, few studies have been conducted along the French Mediterranean coastline. In this study, we report airborne thermal infrared (TIR) images that allowed us to locate several freshwater inputs along the "Côte Bleue" located west of the city of Marseille. We used salinity, radon and radium isotopes to confirm that the TIR signal could be related to SGD. Radon was analyzed in situ along the coastline on board a rubber boat. The four radium isotopes (223Ra, 224Ra, 226Ra, 228Ra) were analyzed in samples collected in the coastal waters characterized by a strong TIR signal, as well as along transects conducted on board RV Antedon II between the coast and offshore (between 200 m and 8 km). We also analyzed nutrient (nitrates, phosphates and silicates) and mercury concentrations in the water samples. Radium isotopes were thus used to quantify SGD fluxes and to determine the fluxes of nutrients and mercury associated with SGD along this coastline.

Shoreline recovery from storms on the east coast of Southern Africa

NASA Astrophysics Data System (ADS)

Corbella, S.; Stretch, D. D.

2012-01-01

Episodic extreme waves due to sea storms can cause severe coastal erosion. The recovery times of such events are important for the analysis of risk and coastal vulnerability. The recovery period of a storm damaged coastline represents a time when the coastline is most vulnerable and nearby infrastructure is at the greatest risk. We propose that identification of the beach recovery period can be used as a coastal management tool when determining beach usage. As a case study, we analyse 37 yr of beach profile data on the east coast of South Africa. Considering beach length and cross-sectional area, we establish a global recovery period and rate and identify the physical characteristics of the coastlines that either accelerate or retard recovery. The beaches in the case study were found to take an average of two years to recover at a rate of approximately 90 m3 m-1 yr-1. Beach profiles with vegetated dunes recovered faster than urbanized beaches. Perpendicular beach structures have both positive and negative effects on beach recovery. Coastlines with rock outcrops in the surf zone tend to recover slowly and long-term sediment loss was identified in cases where storm damaged beaches have not recovered to pre-erosion levels.

Determination of erosion thresholds and aeolian dune stabilization mechanisms via robotic shear strength measurements

NASA Astrophysics Data System (ADS)

Qian, F.; Lee, D. B.; Bodek, S.; Roberts, S.; Topping, T. T.; Robele, Y.; Koditschek, D. E.; Jerolmack, D. J.

2017-12-01

Understanding the parameters that control the spatial variation in aeolian soil erodibility is crucial to the development of sediment transport models. Currently, in-situ measurements of erodibility are time consuming and lack robustness. In an attempt to remedy this issue, we perform field and laboratory tests to determine the suitability of a novel mechanical shear strength method to assess soil erodibility. These tests can be performed quickly ( 1 minute) by a semi-autonomous robot using its direct-drive leg, while environmental controls such as soil moisture and grain size are simultaneously characterized. The robot was deployed at White Sands National Monument to delineate and understand erodibility gradients at two different scales: (1) from dry dune crest to moist interdune (distance 10s m), where we determined that shear strength increases by a factor of three with increasing soil moisture; and (2) from barren barchan dunes to vegetated and crusted parabolics downwind (distance 5 km), where we found that shear strength was enhanced by a factor of two relative to loose sand. Interestingly, shear strength varied little from carbonate-crusted dune surfaces to bio-crust covered interdunes in the downwind parabolic region, indicating that varied surface crusts contribute similarly to erosion resistance. To isolate the control of soil moisture on erodibility, we performed laboratory experiments in a sandbox. These results verify that the observed increase in soil erodibility from barchan crest to interdune at White Sands is dominated by soil moisture, and the variation in parabolic dune and barchan interdune areas results from a combination of soil moisture, bio-activity, and crust development. This study highlights that spatial variation of soil erodibility in arid environments is large enough to significantly affect sediment transport, and that probing soil erodibility with a robot has the potential to improve our understanding of this multifaceted problem.

Using High-Resolution Comparison of Bedrock Properties and Channel Morphology to Empirically Characterize Erodibility in Fluvial Settings

NASA Astrophysics Data System (ADS)

Chilton, K.; Spotila, J. A.

2017-12-01

Bedrock erodibility exerts a primary control on landscape evolution and fluvial morphodynamics, but the relationships between erodibility and the many factors that influence it (rock strength, spacing and orientation of discontinuities, weathering susceptibility, erosive process, etc.) remain poorly defined. This results in oversimplification of erodibility in landscape evolution models, the primary example being the stream power incision model, which groups together factors which may influence erodibility into a single coefficient. There is therefore need to better define how bedrock properties influence erodibility and, in turn, channel form and evolution. This study seeks to deconvolve the relationships between bedrock material properties and erodibility by quantifying empirical relationships between substrate characteristics and bedrock channel morphology (slope, steepness index, width, form) at a high spatial resolution (5-10 m scale) in continuous and mixed alluvial-bedrock channels. We specifically focus on slowly eroding channels with minimal evidence for landscape transience, such that variations in channel morphology are mainly due to bedrock properties. We also use channels cut into sedimentary rock, which exhibit extreme variation (yet predictability and continuity) in discontinuity spacing. Here we present preliminary data comparing the morphology and bedrock properties of 1st through 4th order channels in the tectonically inactive Valley and Ridge province of the Appalachian Mountains, SW Virginia. Field surveys of channel slope, width, substrate, and form consist of 0.5 km long, continuous stream reaches through different intervals of tilted Paleozoic siliciclastic stratigraphy. Some surveys exhibit nearly complete bedrock exposure, whereas others are predominantly mixed, with localized bedrock reaches in high-slope knickzones. We statistically analyze relationships between fluvial morphology and lithology, strength (based on field and laboratory measurements), and discontinuity spacing and orientation. Results are informative for models of landscape evolution, and specifically provide insight into the controls on erosive process dominance (i.e., plucking vs. abrasion) and on the development and evolution of knickpoints in non-transient settings.

Reconstruction of Arctic surface temperature in past 100 years using DINEOF

NASA Astrophysics Data System (ADS)

Zhang, Qiyi; Huang, Jianbin; Luo, Yong

2015-04-01

Global annual mean surface temperature has not risen apparently since 1998, which is described as global warming hiatus in recent years. However, measuring of temperature variability in Arctic is difficult because of large gaps in coverage of Arctic region in most observed gridded datasets. Since Arctic has experienced a rapid temperature change in recent years that called polar amplification, and temperature risen in Arctic is faster than global mean, the unobserved temperature in central Arctic will result in cold bias in both global and Arctic temperature measurement compared with model simulations and reanalysis datasets. Moreover, some datasets that have complete coverage in Arctic but short temporal scale cannot show Arctic temperature variability for long time. Data Interpolating Empirical Orthogonal Function (DINEOF) were applied to fill the coverage gap of NASA's Goddard Institute for Space Studies Surface Temperature Analysis (GISTEMP 250km smooth) product in Arctic with IABP dataset which covers entire Arctic region between 1979 and 1998, and to reconstruct Arctic temperature in 1900-2012. This method provided temperature reconstruction in central Arctic and precise estimation of both global and Arctic temperature variability with a long temporal scale. Results have been verified by extra independent station records in Arctic by statistical analysis, such as variance and standard deviation. The result of reconstruction shows significant warming trend in Arctic in recent 30 years, as the temperature trend in Arctic since 1997 is 0.76°C per decade, compared with 0.48°C and 0.67°C per decade from 250km smooth and 1200km smooth of GISTEMP. And global temperature trend is two times greater after using DINEOF. The discrepancies above stress the importance of fully consideration of temperature variance in Arctic because gaps of coverage in Arctic cause apparent cold bias in temperature estimation. The result of global surface temperature also proves that global warming in recent years is not as slow as thought.

Petrography of impact glasses and melt breccias from the El'gygytgyn impact structure, Russia

NASA Astrophysics Data System (ADS)

Pittarello, Lidia; Koeberl, Christian

2013-07-01

The El'gygytgyn impact structure, 18 km in diameter and 3.6 Ma old, in Arctic Siberia, Russia, is the only impact structure on Earth mostly excavated in acidic volcanic rocks. The Late Cretaceous volcanic target includes lavas, tuffs, and ignimbrites of rhyolitic, dacitic, and andesitic composition, and local occurrence of basalt. Although the ejecta blanket around the crater is nearly completely eroded, bomb-shaped impact glasses, redeposited after the impact event, occur in lacustrine terraces within the crater. Here we present detailed petrographic descriptions of newly collected impact glass-bearing samples. The observed features contribute to constrain the formation of the melt and its cooling history within the framework of the impact process. The collected samples can be grouped into two types, characterized by specific features: (1) "pure" glasses, containing very few clasts or new crystals and which were likely formed during the early stages of cratering and (2) a second type, which represents composite samples with impact melt breccia lenses embedded in silicate glass. These mixed samples probably resulted from inclusion of unmelted impact debris during ejection and deposition. After deposition the glassy portions continued to deform, whereas the impact melt breccia inclusions that probably had already cooled down behaved as rigid bodies in the flow.

78 FR 12033 - Programs and Research Projects Affecting the Arctic

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-21

... ARCTIC RESEARCH COMMISSION Programs and Research Projects Affecting the Arctic Notice is hereby given that the U.S. Arctic Research Commission will hold its 100th meeting in Anchorage and Bethel... presentations concerning Arctic research activities The focus of the meeting will be Arctic research activities...

The Arctic Research Consortium of the United States (ARCUS): Connecting Arctic Research

NASA Astrophysics Data System (ADS)

Rich, R. H.; Wiggins, H. V.; Creek, K. R.; Sheffield Guy, L.

2015-12-01

This presentation will highlight the recent activities of the Arctic Research Consortium of the United States (ARCUS) to connect Arctic research. ARCUS is a nonprofit membership organization of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic science community to keep apprised of relevant news, meetings, and announcements. Coordination for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Scenarios Creation and Use in the Arctic Council's Arctic Marine Shipping Assessment

NASA Astrophysics Data System (ADS)

Brigham, L. W.

2016-12-01

The Arctic Council's Arctic Marine Shipping Assessment (AMSA), conducted 2004-2009, used a scenarios-based approach to reveal the complexity of future Arctic marine navigation and to develop a set of plausible futures. The initial task was to use experts and stakeholders in brainstorming sessions to identify the key drivers and uncertainties for Arctic marine navigation. AMSA scenario participants identified 120 driving forces or factors that may influence future levels of marine activity. This effort illustrated the broad, global connections that can impact future use of the Arctic Ocean. Two primary factors were selected to anchor, as axes of uncertainty, the scenarios matrix: resources and trade (the level of demand for Arctic natural resources and trade); and, governance (the degree of relative stability of rules and standards for marine use both within the Arctic and internationally). Four scenarios were created by crossing the two primary drivers: a Polar Lows scenario (low demand and unstable governance); an Arctic Race scenario (high demand and unstable governance); a Polar Preserve scenario (low demand and stable governance); and, an Arctic Saga scenario (high demand and stable governance). The AMSA scenarios effort proved to be an effective and powerful way to communicate to the Arctic Council diplomats, Arctic indigenous peoples, maritime stakeholders and many other actors in the global community the complexities influencing the future of Arctic shipping and marine operations. The scenarios approach facilitated unconstrained thinking and identified the many plausible linkages of the Arctic to the global economic system. The AMSA scenarios work was influential in the Arctic ministers' approval of the framework set of AMSA recommendations that are being implemented today to enhance Arctic marine safety and environmental protection.

The International Polar year 2007-2008; the Arctic human health legacy.

PubMed

Parkinson, Alan J

2007-01-01

Life expectancy in Arctic populations has greatly improved over the last 50 years. Much of this improvement can be attributed health research that has resulted in a reduction in morbidity and mortality from infectious diseases, such as tuberculosis, and the vaccine-preventable diseases of childhood. However, despite these improvements in health indicators of Arctic residents, life expectancy and infant mortality remain higher in indigenous Arctic residents in the US Arctic, northern Canada, and Greenland when compared to Arctic residents of Nordic countries. The International Polar Year (IPY) represents a unique opportunity to focus world attention on Arctic human health and to further stimulate Circumpolar cooperation on emerging Arctic human health concerns. The Arctic Human Health Initiative (AHHI) is an Arctic Council IPY initiative that aims to build and expand on existing Arctic Council and International Union for Circumpolar Health (IUCH) human health research activities. The human health legacy of the IPY will be increased visibility of the human health concerns of Arctic communities, revitalization of cooperative Arctic human health research focused on those concerns, the development of health policies based on research findings, and the subsequent implementation of appropriate interventions, prevention and control measures at the community level.

Wind-Eroded Landscape

NASA Technical Reports Server (NTRS)

2005-01-01

5 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust-mantled, wind-eroded landscape in the Medusae Sulci region of Mars. Wind eroded the bedrock in this region, and then, later, windblown dust covered much of the terrain.

Location near: 5.7oS, 160.2oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

The Arctic zone: possibilities and risks of development

NASA Astrophysics Data System (ADS)

Sentsov, A.; Bolsunovskaya, Y.; Melnikovich, E.

2016-09-01

The authors analyze the Arctic region innovative possibilities from the perspective of political ideology and strategy. The Arctic region with its natural resources and high economic potential attracts many companies and it has become an important area of transnational development. At present, the Arctic region development is of great importance in terms of natural resource management and political system development. However, the most important development issue in the Arctic is a great risk of different countries’ competing interests in economic, political, and legal context. These are challenges for international partnership creating in the Arctic zone, Russian future model developing for the Arctic, and recognition of the Arctic as an important resource for the Russians. The Russian economic, military, and political expansion in the Arctic region has the potential to strengthen the national positions. The authors present interesting options for minimizing and eliminating political risks during the Arctic territories development and define an effective future planning model for the Russian Arctic.

The Arctic Visiting Speakers Program

NASA Astrophysics Data System (ADS)

Wiggins, H. V.; Fahnestock, J.

2013-12-01

The Arctic Visiting Speakers Program (AVS) is a program of the Arctic Research Consortium of the U.S. (ARCUS) and funded by the National Science Foundation. AVS provides small grants to researchers and other Arctic experts to travel and share their knowledge in communities where they might not otherwise connect. The program aims to: initiate and encourage arctic science education in communities with little exposure to arctic research; increase collaboration among the arctic research community; nurture communication between arctic researchers and community residents; and foster arctic science education at the local level. Individuals, community organizations, and academic organizations can apply to host a speaker. Speakers cover a wide range of arctic topics and can address a variety of audiences including K-12 students, graduate and undergraduate students, and the general public. Preference is given to tours that reach broad and varied audiences, especially those targeted to underserved populations. Between October 2000 and July 2013, AVS supported 114 tours spanning 9 different countries, including tours in 23 U.S. states. Tours over the past three and a half years have connected Arctic experts with over 6,600 audience members. Post-tour evaluations show that AVS consistently rates high for broadening interest and understanding of arctic issues. AVS provides a case study for how face-to-face interactions between arctic scientists and general audiences can produce high-impact results. Further information can be found at: http://www.arcus.org/arctic-visiting-speakers.

Ano Nuevo to Santa Cruz, California : a photographic tour of the coastline

USGS Publications Warehouse

Chezar, Henry; Wong, Florence L.

2000-01-01

This interactive CD ROM contains over 500 overlapping photographic images of the California coastline from A?o Nuevo to Santa Cruz. The images were taken from the R/V David Johnston to illustrate the coastal geology adjacent to part of the Monterey Bay National Marine Sanctuary. The introductory home page starts a series of links to a regional map, more detailed area maps, and finally the individual photographic images.

Boston, MA and New England Coastline

NASA Image and Video Library

1973-06-22

SL2-05-381 (22 June 1973) --- Boston, MA and the New England Coastline (43.5N, 84.0W) can be seen in this view. The typical rugged rocky coast of Maine is the result of heavy glacial action producing the rocky cliffs, jagged spurs of land and islands that characterize Main's Atlantic Coast. During the last Ice Age, extensive sediments were laid down producing a landscape of rolling hills with rocky outcrops. Photo credit: NASA

Images

Science.gov Websites

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Polycyclic aromatic hydrocarbon-DNA adducts in Beluga whales from the Arctic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathieu, A.; Payne, J.F.; Fancey, L.L.

1997-09-01

The Arctic is still relatively pristine in nature, but it is also vulnerable to pollution because contaminants originating from midlatitudes are transported to the Arctic by atmospheric processes, ocean currents, and river. Recognition of this fact of Arctic vulnerability has resulted in a Declaration on the Protection of the Arctic Environment by eight Arctic countries. A manifest aim of this declaration is to develop an Arctic Monitoring and Assessment Program. We report here on the presence of measurable levels of polycyclic aromatic hydrocarbon-DNA adducts, including relatively high levels in Arctic beluga (Delphinapterus leucas). These results lend support to the valuemore » of developing biological assessment programs for Arctic wildlife. 15 refs., 1 tab.« less

Geomorphology and dynamics of a traveling cuspate foreland, Authie estuary, France

NASA Astrophysics Data System (ADS)

Hesp, Patrick A.; Ruz, Marie-Hélène; Hequette, Arnaud; Marin, Denis; Miot da Silva, Graziela

2016-02-01

Cuspate forelands or salients occur all over the world in lakes, estuaries and on ocean shores, yet there have been few studies conducted on traveling cuspate forelands (or salients), that is, forelands that migrate or travel alongshore. This paper presents a study of a traveling foreland in the Authie estuary, France, termed the Bec du Perroquet. Historical shoreline changes may be traced from the 1200's AD and the region has experienced both marked intertidal-subtidal accretion extending from the south, and massive erosion in the north since this period. An analysis of aerial photographs from 1947 until the present shows that the original Bec foreland was established at the mouth of the Authie estuary, but gradually disappeared by the 1960's and a new foreland developed in the middle of the northern-central portion of the bay. This foreland was composed of a suite of foredune ridges which have been successively eroded on the northern margin and initiated on the southern margin as the foreland traveled or migrated southwards. As the foreland traveled south, from 1947 to 2009 the northern part of the bay retreated more than 350 m, while mid-bay, the coastline retreated ~ 215 m. As the foreland evolves and migrates, incipient foredunes can develop rapidly (e.g. 18 ridges formed in an 11 week period), while at other times the ridges form slowly and may be eroded and disappear. Two or more foredune ridges may blend into a single ridge over time depending on the initial degree of vegetation cover on the ridge and swale set. Aeolian processes in dune swales are much more important in this system than in typical prograding foredune plain systems due to the sometimes marked lack of vegetation colonization in the swales following foredune ridge development, and aeolian deflation of the swales (along with blowout development) is important particularly when they become open conduits to the beach as erosion of the NW foreland proceeds. The ages of each of the surviving ridges on the foreland in 2009 have been determined, and the evolutionary path of the ridges ascertained. Formerly intact, relatively stable, continuous ridges evolve to erosional knobs, turrets and nebkha over time. Foredune ridges (and swales) can be extremely arcuate to semi-circular in form where the foreland and especially the spit extension are exposed to a wide range of wind directions and where the shoreline trends through an arc of at least 270°. This study illustrates a remarkable cycling of the formation, destruction and reformation (travel) of a cuspate foreland over a ~ 50 + year period.

Cessation of oil exposure in harlequin ducks after the Exxon Valdez oil spill: Cytochrome P4501A biomarker evidence

USGS Publications Warehouse

Esler, Daniel N.; Ballachey, Brenda E.; Bowen, Lizabeth; Miles, A. Keith; Dickson, Rian D.; Henderson, John D.

2017-01-01

The authors quantified hepatic hydrocarbon-inducible cytochrome P4501A (CYP1A) expression, as ethoxyresorufin-O-deethylase (EROD) activity, in wintering harlequin ducks (Histrionicus histrionicus) captured in Prince William Sound, Alaska (USA), during 2011, 2013, and 2014 (22–25 yr following the 1989 Exxon Valdez oil spill). Average EROD activity was compared between birds from areas oiled by the spill and those from nearby unoiled areas. The present study replicated studies conducted from 1998 to 2009 demonstrating that harlequin ducks using areas oiled in 1989 had elevated EROD activity, indicative of oil exposure, up to 2 decades post spill. In the present study, it was found that average EROD activity during March 2011 was significantly higher in wintering harlequin ducks captured in oiled areas relative to unoiled areas, which the authors interpret to indicate that harlequin ducks continued to be exposed to residual Exxon Valdez oil up to 22 yr after the original spill. However, the 2011 results also indicated reductions in exposure relative to previous years. Average EROD activity in birds from oiled areas was approximately 2 times that in birds from unoiled areas in 2011, compared with observations from 2005 to 2009, in which EROD activity was 3 to 5 times higher in oiled areas. It was also found that average EROD activity during March 2013 and March 2014 was not elevated in wintering harlequin ducks from oiled areas. The authors interpret these findings to indicate that exposure of harlequin ducks to residual Exxon Valdez oil abated within 24 yr after the original spill. The present study finalizes a timeline of exposure, extending over 2 decades, for a bird species thought to be particularly vulnerable to oil contamination in marine environments

Cytological changes in association with ethoxyresorufin o-deethylase induction in fish upon dietary exposure to benzo[a]pyrene.

PubMed

Au, Doris W T; Chen, Ping; Pollino, Carmel A

2004-04-01

Juvenile areolated grouper (Epinephelus areolatus) were exposed to two levels of dietary benzo[a]pyrene (BaP; 0.25-12.5 microg/g body wt/d) for four weeks, followed by four weeks of depuration. Significant increase in hepatic ethoxyresorufin O-deethylase (EROD) activities was found after one week, preceding an increase in lipopigments (as measured by quantitative transmission electron microscopy) in week 2 of exposure. The EROD activities in the BaP-treated fish subsided at week 4 of exposure and throughout the depuration period. Lipopigments in the high-dose group appeared to be more persistent than that of the EROD activity during the exposure period and remained significantly higher than that of the controls at week 4. Levels of lipopigments, however, rapidly subsided on withdrawal of BaP exposure. These results appear to suggest that changes in EROD activities would precede cytological changes and that both the observed cytological and biochemical changes are reversible. Results of the present study also lend further support to our earlier findings on Solea ovata, that a significant relationship exists between EROD activity and lipopigment accumulation (as measured by volume density, absolute volume, numerical density, and absolute density; r = 0.483-0.358, p < 0.05), regardless of fish species (S. ovata and aerolated grouper) as well as the routes of exposure to BaP (intraperitoneal injection or dietary exposure). This provides strong supporting evidence that elevated EROD activities in fish liver do not merely indicate exposure to polyaromatic hydrocarbons (PAHs) but are also associated with significant biological effects. Our results showed that hepatic EROD activity and lipopigments could be used to indicate recent exposure of the fish to BaP/PAHs.

Diagnostic evaluation of the Community Earth System Model in simulating mineral dust emission with insight into large-scale dust storm mobilization in the Middle East and North Africa (MENA)

NASA Astrophysics Data System (ADS)

Parajuli, Sagar Prasad; Yang, Zong-Liang; Lawrence, David M.

2016-06-01

Large amounts of mineral dust are injected into the atmosphere during dust storms, which are common in the Middle East and North Africa (MENA) where most of the global dust hotspots are located. In this work, we present simulations of dust emission using the Community Earth System Model Version 1.2.2 (CESM 1.2.2) and evaluate how well it captures the spatio-temporal characteristics of dust emission in the MENA region with a focus on large-scale dust storm mobilization. We explicitly focus our analysis on the model's two major input parameters that affect the vertical mass flux of dust-surface winds and the soil erodibility factor. We analyze dust emissions in simulations with both prognostic CESM winds and with CESM winds that are nudged towards ERA-Interim reanalysis values. Simulations with three existing erodibility maps and a new observation-based erodibility map are also conducted. We compare the simulated results with MODIS satellite data, MACC reanalysis data, AERONET station data, and CALIPSO 3-d aerosol profile data. The dust emission simulated by CESM, when driven by nudged reanalysis winds, compares reasonably well with observations on daily to monthly time scales despite CESM being a global General Circulation Model. However, considerable bias exists around known high dust source locations in northwest/northeast Africa and over the Arabian Peninsula where recurring large-scale dust storms are common. The new observation-based erodibility map, which can represent anthropogenic dust sources that are not directly represented by existing erodibility maps, shows improved performance in terms of the simulated dust optical depth (DOD) and aerosol optical depth (AOD) compared to existing erodibility maps although the performance of different erodibility maps varies by region.

The Age of the Arctic.

ERIC Educational Resources Information Center

Young, Oran R.

1986-01-01

Examines trends related to exploration in the Arctic by considering: (1) technology and military strategies; (2) foreign policy and the Arctic; (3) Arctic industrialization; (4) the Arctic policy agenda; and (5) recent United States initiatives in this region. (JN)

Arctic tipping points in an Earth system perspective.

PubMed

Wassmann, Paul; Lenton, Timothy M

2012-02-01

We provide an introduction to the volume The Arctic in the Earth System perspective: the role of tipping points. The terms tipping point and tipping element are described and their role in current science, general debates, and the Arctic are elucidated. From a wider perspective, the volume focuses upon the role of humans in the Arctic component of the Earth system and in particular the envelope for human existence, the Arctic ecosystems. The Arctic climate tipping elements, the tipping elements in Arctic ecosystems and societies, and the challenges of governance and anticipation are illuminated through short summaries of eight publications that derive from the Arctic Frontiers conference in 2011 and the EU FP7 project Arctic Tipping Points. Then some ideas based upon resilience thinking are developed to show how wise system management could ease pressures on Arctic systems in order to keep them away from tipping points.

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

PubMed Central

Zumstein, Katrin; Peutzfeldt, Anne; Lussi, Adrian

2018-01-01

This study investigated the effect of SnCl2/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl2/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl2/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl2/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

Modulation of ethoxyresorufin O-deethylase and glutathione S-transferase activities in Nile tilapia (Oreochromis niloticus) by polycyclic aromatic hydrocarbons containing two to four rings: implications in biomonitoring aquatic pollution.

PubMed

Pathiratne, Asoka; Hemachandra, Chamini K

2010-08-01

Despite ubiquity of polycyclic aromatic hydrocarbons (PAHs) in the tropical environments, little information is available concerning responses of tropical fish to PAHs and associated toxicity. In the present study, effects of five PAHs containing two to four aromatic rings on hepatic CYP1A dependent ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST) and serum sorbitol dehydrogenase (SDH) activities in Nile tilapia, a potential fish species for biomonitoring pollution in tropical waters, were evaluated. Results showed that EROD activities were induced by the PAHs containing four aromatic rings (pyrene and chrysene) in a dose dependent manner. However PAHs with two to three aromatic rings (naphthalene, phenanthrene and fluoranthene) caused no effect or inhibition of EROD activities depending on the dose and the duration. Fluoranthene was the most potent inhibitor. SDH results demonstrated that high doses of fluoranthene induced hepatic damage. GST activity was induced by the lowest dose of phenanthrene, fluoranthene and chrysene but high doses had no effect. The results indicate that induction of EROD enzyme in Nile tilapia is a useful biomarker of exposure to PAHs such as pyrene and chrysene. However EROD inhibiting PAHs such as fluoranthene in the natural environment may modulate the EROD inducing potential of other PAHs thereby influencing PAH exposure assessments.

Prediction of erodibility in Oxisols using iron oxides, soil color and diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Arantes Camargo, Livia; Marques, José, Jr.

2015-04-01

The prediction of erodibility using indirect methods such as diffuse reflectance spectroscopy could facilitate the characterization of the spatial variability in large areas and optimize implementation of conservation practices. The aim of this study was to evaluate the prediction of interrill erodibility (Ki) and rill erodibility (Kr) by means of iron oxides content and soil color using multiple linear regression and diffuse reflectance spectroscopy (DRS) using regression analysis by least squares partial (PLSR). The soils were collected from three geomorphic surfaces and analyzed for chemical, physical and mineralogical properties, plus scanned in the spectral range from the visible and infrared. Maps of spatial distribution of Ki and Kr were built with the values calculated by the calibrated models that obtained the best accuracy using geostatistics. Interrill-rill erodibility presented negative correlation with iron extracted by dithionite-citrate-bicarbonate, hematite, and chroma, confirming the influence of iron oxides in soil structural stability. Hematite and hue were the attributes that most contributed in calibration models by multiple linear regression for the prediction of Ki (R2 = 0.55) and Kr (R2 = 0.53). The diffuse reflectance spectroscopy via PLSR allowed to predict Interrill-rill erodibility with high accuracy (R2adj = 0.76, 0.81 respectively and RPD> 2.0) in the range of the visible spectrum (380-800 nm) and the characterization of the spatial variability of these attributes by geostatistics.

The Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Fox, S. E.; Wiggins, H. V.; Creek, K. R.

2012-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. Founded in 1988 to serve as a forum for advancing interdisciplinary studies of the Arctic, ARCUS synthesizes and disseminates scientific information on arctic research and educates scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS works closely with national and international stakeholders in advancing science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program for K-12 educators and researchers to work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic community to keep apprised of relevant news, meetings, and announcements. - Project Office for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

The Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Creek, K. R.; Fox, S. E.

2013-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. Founded in 1988 to serve as a forum for advancing interdisciplinary studies of the Arctic, ARCUS synthesizes and disseminates scientific information on arctic research and educates scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS works closely with national and international stakeholders in advancing science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program for K-12 educators and researchers to work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic community to keep apprised of relevant news, meetings, and announcements. - Project Office for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

The Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Fox, S. E.; Wiggins, H. V.

2011-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic science community to keep apprised of relevant news, meetings, and announcements. - Coordination for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic.

Biochemical indicators of contaminant exposure in birds and turtles of the Great Lakes-St. Lawrence River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bishop, C.; Trudeau, S.; Kennedy, S.

1995-12-31

Pre-fledgling chicks of tree swallows, double-crested cormorants, herring gulls, common terns and hatchling snapping turtles were collected from contaminated Areas of Concern and reference sites in the Great Lakes and St. Lawrence River to determine the geographic and species variation in biomarker responses. EROD activity in colonial waterbirds was generally an order of magnitude above EROD activity in tree swallows and snapping turtles. Notably, EROD activity in colonial waterbirds did not correlate with organochlorine contamination in livers at one industrialized site suggesting that exposure to other contaminants, possibly PAHs, may be an important factor. Retinol concentrations in cormorants were non-detectablemore » and retinyl palmitate concentrations were equal or greater than those in herring gulls. In tree swallows, there was a significant negative correlation between vitamin A concentration in liver and kidney and EROD activity. In snapping turtles, there was a significant induction in EROD activity and significantly higher cytochrome P450 IAI level in livers from the Great Lakes site relative to a clean inland location. There were no significant differences in porphyrin concentrations between sites.« less

Repeated erosion of cohesive sediments with biofilms

NASA Astrophysics Data System (ADS)

Valentine, K.; Mariotti, G.; Fagherazzi, S.

2014-04-01

This study aims to explore the interplay between biofilms and erodability of cohesive sediments. Erosion experiments were run in four laboratory annular flumes with natural sediments. After each erosion the sediment was allowed to settle, mimicking intermittent physical processes like tidal currents and waves. The time between consecutive erosion events ranged from 1 to 12 days. Turbidity of the water column caused by sediment resuspension was used to determine the erodability of the sediments with respect to small and moderate shear stresses. Erodability was also compared on the basis of the presence of benthic biofilms, which were quantified using a Pulse-Amplitude Modulation (PAM) Underwater Fluorometer. We found that frequent erosion lead to the establishment of a weak biofilm, which reduced sediment erosion at small shear stresses (around 0.1 Pa). If prolonged periods without erosion were present, the biofilm fully established, resulting in lower erosion at moderate shear stresses (around 0.4 Pa). We conclude that an unstructured extracellular polymeric substances (EPS) matrix always affect sediment erodability at low shear stresses, while only a fully developed biofilm mat can reduce sediment erodability at moderate shear stresses.

Investigating the effect of lignosulfonate on erosion rate of the embankments constructed with clayey sand.

PubMed

Koohpeyma, Hamid Reza; Vakili, Amir Hossein; Moayedi, Hossein; Panjsetooni, Alireza; Nazir, Ramli

2013-01-01

Internal erosion is known as the most important cause of dam failure after overtopping. It is important to improve the erosion resistance of the erodible soil by selecting an effective technique along with the reasonable costs. To prevent internal erosion of embankment dams the use of chemical stabilizers that reduce the soil erodibility potential is highly recommended. In the present study, a lignin-based chemical, known as lignosulfonate, is used to improve the erodibility of clayey sand specimen. The clayey sand was tested in various hydraulic heads in terms of internal erosion in its natural state as well as when it is mixed with the different percentages of lignosulfonate. The results show that erodibility of collected clayey sand is very high and is dramatically reduced by adding lignosulfonate. Adding 3% of lignosulfonate to clayey sand can reduce the coefficient of soil erosion from 0.01020 to 0.000017. It is also found that the qualitative erodibility of stabilized soil with 3% lignosulfonate is altered from the group of extremely rapid to the group of moderately slow.

Correlation of antimutagenic activity and suppression of CYP1A with the lipophilicity of alkyl gallates and other phenolic compounds.

PubMed

Feng, Qing; Kumagai, Takeshi; Nakamura, Yoshimasa; Uchida, Koji; Osawa, Toshihiko

2003-05-09

Alkyl gallates are widely used as food antioxidants. Methyl, ethyl, propyl, lauryl, and cetyl gallates showed antimutagenicity to activated 2-aminoanthracene (2AA)-induced SOS responses in Salmonella typhimurium TA1535/pSK1002. They also exhibited a suppressive effect on 3-methylcholanthrene (3-MC)-induced cytochrome P450 1A (CYP1A) in human hepatoma HepG2 cells, as indexed by the 7-ethoxyresorufin-O-deethylase (EROD) activity, and on CYP1A protein level. Both antimutagenicity and suppression of CYP1A appeared to be dependent on alkyl chain lengths, which suggested lipophilicity dependence. Based on those results, we investigated 26 other phenolic compounds for their lipophilicity, antimutagenicity and inhibition of EROD activity. The lipophilicity correlated well with the inhibition of EROD activity (r=0.78), and the inhibition of EROD activity correlated with the antimutagenicity of those compounds (r=0.71). The results suggest that the lipophilicity of the phenolic compounds may be an important factor in their ability to inhibit EROD activity.

Investigating the Effect of Lignosulfonate on Erosion Rate of the Embankments Constructed with Clayey Sand

PubMed Central

Koohpeyma, Hamid Reza; Vakili, Amir Hossein; Panjsetooni, Alireza; Nazir, Ramli

2013-01-01

Internal erosion is known as the most important cause of dam failure after overtopping. It is important to improve the erosion resistance of the erodible soil by selecting an effective technique along with the reasonable costs. To prevent internal erosion of embankment dams the use of chemical stabilizers that reduce the soil erodibility potential is highly recommended. In the present study, a lignin-based chemical, known as lignosulfonate, is used to improve the erodibility of clayey sand specimen. The clayey sand was tested in various hydraulic heads in terms of internal erosion in its natural state as well as when it is mixed with the different percentages of lignosulfonate. The results show that erodibility of collected clayey sand is very high and is dramatically reduced by adding lignosulfonate. Adding 3% of lignosulfonate to clayey sand can reduce the coefficient of soil erosion from 0.01020 to 0.000017. It is also found that the qualitative erodibility of stabilized soil with 3% lignosulfonate is altered from the group of extremely rapid to the group of moderately slow. PMID:24459437

The 1994 Arctic Ocean Section. The First Major Scientific Crossing of the Arctic Ocean,

DTIC Science & Technology

1996-09-01

contribute to the international effort to better understand the role of the Arctic Ocean in the global carbon cycle and climate change. Summar...Barium Distributions in the Arctic Ocean ? ........................ 32 Biology and the Carbon Cycle Cycling of Organic Carbon in the Central Arctic...of Heterotrophic Bacteria and Protists in the Arctic Ocean Carbon Cycle............. 40

High mountain origin, phylogenetics, evolution, and niche conservatism of arctic lineages in the hemiparasitic genus Pedicularis (Orobanchaceae).

PubMed

Tkach, Natalia; Ree, Richard H; Kuss, Patrick; Röser, Martin; Hoffmann, Matthias H

2014-07-01

The origin of the arctic flora covering the northernmost treeless areas is still poorly understood. Arctic plants may have evolved in situ or immigrated from the adjacent ecosystems. Frequently arctic species have disjunctive distributions between the Arctic and high mountain systems of the temperate zone. This pattern may result from long distance dispersal or from glacial plant migrations and extinctions of intermediate populations. The hemiparasitic genus Pedicularis is represented in the Arctic by c. 28 taxa and ranks among the six most species-rich vascular plant genera of this region. In this study, we test the hypothesis that these lineages evolved from predecessors occurring in northern temperate mountain ranges, many of which are current centers of diversity for the genus. We generated a nuclear ribosomal and chloroplast DNA phylogeny including almost all of the arctic taxa and nearly half of the genus as a whole. The arctic taxa of Pedicularis evolved 12-14 times independently and are mostly nested in lineages that otherwise occur in the high mountains of Eurasia and North America. It appears that only three arctic lineages arose from the present-day center of diversity of the genus, in the Hengduan Mountains and Himalayas. Two lineages are probably of lowland origin. Arctic taxa of Pedicularis show considerable niche conservatism with respect to soil moisture and grow predominantly in moist to wet soils. The studied characteristics of ecology, morphology, and chromosome numbers of arctic Pedicularis show a heterogeneous pattern of evolution. The directions of morphological changes among the arctic lineages show opposing trends. Arctic taxa are chiefly diploid, the few tetraploid chromosome numbers of the genus were recorded only for arctic taxa. Five arctic Pedicularis are annuals or biennials, life forms otherwise rare in the Arctic. Other genera of the Orobanchaceae consist also of an elevated number of short-lived species, thus hemiparasitism may favor this life form in the Arctic. Copyright © 2014 Elsevier Inc. All rights reserved.

Identifying Priorities for International Arctic Research and Policy

NASA Astrophysics Data System (ADS)

Rachold, V.; Hik, D.; Barr, S.

2015-12-01

The International Arctic Science Committee (IASC) is a non-governmental, international scientific organization, founded in 1990 by representatives of national scientific organizations of the eight Arctic countries - Canada, Denmark, Finland, Iceland, Norway, Russia (at that time Union of Soviet Socialist Republics), Sweden and the United States of America. Over the past 25 years, IASC has evolved into the leading international science organization of the North and its membership today includes 23 countries involved in all aspects of Arctic research, including 15 non-Arctic countries (Austria, China, the Czech Republic, France, Germany, India, Italy, Japan, the Netherlands, Poland, Portugal, South Korea, Spain, Switzerland and the UK). The Founding Articles committed IASC to pursue a mission of encouraging and facilitating cooperation in all aspects of Arctic research, in all countries engaged in Arctic research and in all areas of the Arctic region. IASC promotes and supports leading-edge multi-disciplinary research in order to foster a greater scientific understanding of the Arctic region and its role in the Earth system. IASC has organized three forward-looking conferences focused on international and interdisciplinary perspectives for advancing Arctic research cooperation and applications of Arctic knowledge. Indeed, the IASC Founding Articles call for IASC to host these conferences periodically in order to "review the status of Arctic science, provide scientific and technical advice, and promote cooperation and links with other national and international organizations." Through its members, including national science organizations and funding agencies from all countries engaged in Arctic research, IASC is uniquely placed to undertake this task. As an accredited observer on the Arctic Council, IASC is also in the position to introduce the outcome of its science planning efforts into the Arctićs main political body and to liaise with the Arctic Council Permanent Participants. This paper presents an overview of IASC´s efforts and achievements in terms of identifying Arctic research priorities and providing scientific expertise to policy makers and people who live in or near the Arctic.

Role of Greenland meltwater in the changing Arctic

NASA Astrophysics Data System (ADS)

Dukhovskoy, Dmitry; Proshutinsky, Andrey; Timmermans, Mary-Louise; Myers, Paul; Platov, Gennady; Bamber, Jonathan; Curry, Beth; Somavilla, Raquel

2016-04-01

Observational data show that the Arctic ocean-ice-atmosphere system has been changing over the last two decades. Arctic change is manifest in the atypical behavior of the climate indices in the 21st century. Before the 2000s, these indices characterized the quasi-decadal variability of the Arctic climate related to different circulation regimes. Between 1948 and 1996, the Arctic atmospheric circulation alternated between anticyclonic circulation regimes and cyclonic circulation regimes with a period of 10-15 years. Since 1997, however, the Arctic has been dominated by an anticyclonic regime. Previous studies indicate that in the 20th century, freshwater and heat exchange between the Arctic Ocean and the sub-Arctic seas were self-regulated and their interactions were realized via quasi-decadal climate oscillations. What physical processes in the Arctic Ocean - sub-Arctic ocean-ice-atmosphere system are responsible for the observed changes in Arctic climate variability? The presented work is motivated by our hypothesis that in the 21st century, these quasi-decadal oscillations have been interrupted as a result of an additional freshwater source associated with Greenland Ice Sheet melt. Accelerating since the early 1990s, the Greenland Ice Sheet mass loss exerts a significant impact on thermohaline processes in the sub-Arctic seas. Surplus Greenland freshwater, the amount of which is about a third of the freshwater volume fluxed into the region during the 1970s Great Salinity Anomaly event, can spread and accumulate in the sub-Arctic seas influencing convective processes there. It is not clear, however, whether Greenland freshwater can propagate into the interior convective regions in the Labrador Sea and the Nordic Seas. In order to investigate the fate and pathways of Greenland freshwater in the sub-Arctic seas and to determine how and at what rate Greenland freshwater propagates into the convective regions, several numerical experiments using a passive tracer to track propagation of Greenland freshwater have been conducted as a part of the Forum for Arctic Ocean Modeling and Observational Synthesis effort. The presentation discusses the role of Greenland meltwater in the Arctic environment and how this can explain observed cessation of the quasi-decadal Arctic variability. The rate and pathways of Greenland meltwater in the sub-Arctic seas derived from the coordinated model experiments are analyzed. The presented study discusses a possible scenario of the Arctic in the future. It is argued that Greenland meltwater being accumulated in the sub-Arctic seas since the 1990s can trigger a negative feedback mechanism that may impede or even reverse processes of Arctic warming observed in the 21st century.

Holocene evolution of Dahab coastline - Gulf of Aqaba, Sinai Peninsula, Egypt

NASA Astrophysics Data System (ADS)

Torab, Magdy

2018-03-01

Dahab is a little Bedouin-village in Sinai Peninsula on the east coast of the Gulf of Aqaba and it lies approximately 90 km north of Sharm-el-Sheikh City. Dahab means "gold" in the Arabic language; over the past 20 years it has become one of the most visited tourist sites in Egypt. The basement complex is composed mostly of biotite aplite-granite, mica-aplite granite, granodiorite, quartz diorite, alaskite, and diorite. This composition correlates to similar igneous rocks in the most southern areas of Sinai and the Red Sea. Wadi Dahab is composed of igneous and metamorphic rocks and the coastline is formed of fragments of its rocks mixed with fragments of coral reef. The morphology of Dahab's coastline is characterized by a hooked marine spit composed of fluvial sediments carried by marine currents from the mouth of Wadi Dahab. This spit encloses a shallow lagoon, but the active deposition on the lagoon bottom will turn it into saline marsh. This paper investigates the evolution of the Dahab spit and lagoon during the Holocene and over the last 100 years, as well as the potential impacts of future management of the coastal area. The coastline mapping during the study was dependent on GIS techniques and data were collected by using total station, aerial photographs and satellite image interpretation as well as soil sample dating.

Development of a Distributed Source Containment Transport, Transformation, and Fate (CTT&F) Sub-Model for Military Installations

DTIC Science & Technology

2007-08-01

includes soil erodibility terms from the Universal Soil Lass Equation ( USLE ) for estimating the overland sediment transport capacity (for both the x and y...q = unit flow rate of water = va h [L2/T] vc = critical velocity for erosion overland [L/T] K = USLE soil erodibility factor C = USLE soil ...cover factor P = USLE soil management practice factor Be = width of eroding surface in flow direction [L]. In channels, sediment particles can be

Arctic rabies--a review.

PubMed

Mørk, Torill; Prestrud, Pål

2004-01-01

Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies including its distribution and epidemiology.

Behavioral interactions of penned red and arctic foxes

USGS Publications Warehouse

Rudzinski, D.R.; Graves, H.B.; Sargeant, A.B.; Storm, G.L.

1982-01-01

Expansion of the geographical distribution of red foxes (Vulpes vulpes) into the far north tundra region may lead to competition between arctic (Alopex lagopus) and red foxes for space and resources. Behavioral interactions between red and arctic foxes were evaluated during 9 trials conducted in a 4.05-ha enclosure near Woodworth, North Dakota. Each trial consisted of introducing a male-female pair of arctic foxes into the enclosure and allowing them to acclimate for approximately a week before releasing a female red fox into the enclosure, followed by her mate a few days later. In 8 of 9 trials, red foxes were dominant over arctic foxes during encounters. Activity of the arctic foxes decreased upon addition of red foxes. Arctic foxes tried unsuccessfully to defend preferred den, resting, and feeding areas. Even though the outcome of competition between red and arctic foxes in the Arctic is uncertain, the more aggressive red fox can dominate arctic foxes in direct competition for den sites and other limited resources.

Global warming and effects on the Arctic fox.

PubMed

Fuglei, Eva; Ims, Rolf Anker

2008-01-01

We predict the effect of global warming on the arctic fox, the only endemic terrestrial predatory mammals in the arctic region. We emphasize the difference between coastal and inland arctic fox populations. Inland foxes rely on peak abundance of lemming prey to sustain viable populations. In the short-term, warmer winters result in missed lemming peak years and reduced opportunities for successful arctic fox breeding. In the long-term, however, warmer climate will increase plant productivity and more herbivore prey for competitive dominant predators moving in from the south. The red fox has already intruded the arctic region and caused a retreat of the southern limit of arctic fox distribution range. Coastal arctic foxes, which rely on the richer and temporally stable marine subsidies, will be less prone to climate-induced resource limitations. Indeed, arctic islands, becoming protected from southern species invasions as the extent of sea ice is decreasing, may become the last refuges for coastal populations of Arctic foxes.

Relative sensitivity of Arctic species to physically and chemically dispersed oil determined from three hydrocarbon measures of aquatic toxicity.

PubMed

Bejarano, Adriana C; Gardiner, William W; Barron, Mace G; Word, Jack Q

2017-09-15

The risks to Arctic species from oil releases is a global concern, but their sensitivity to chemically dispersed oil has not been assessed using a curated and standardized dataset from spiked declining tests. Species sensitivity to dispersed oil was determined by their position within species sensitivity distributions (SSDs) using three measures of hydrocarbon toxicity: total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbon (PAHs), and naphthalenes. Comparisons of SSDs with Arctic/sub-Arctic versus non-Arctic species, and across SSDs of compositionally similar oils, showed that Arctic and non-Arctic species have comparable sensitivities even with the variability introduced by combining data across studies and oils. Regardless of hydrocarbon measure, hazard concentrations across SSDs were protective of sensitive Arctic species. While the sensitivities of Arctic species to oil exposures resemble those of commonly tested species, PAH-based toxicity data are needed for a greater species diversity including sensitive Arctic species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Levels and trends of contaminants in humans of the Arctic.

PubMed

Gibson, Jennifer; Adlard, Bryan; Olafsdottir, Kristin; Sandanger, Torkjel Manning; Odland, Jon Øyvind

2016-01-01

The Arctic Monitoring and Assessment Programme (AMAP) is one of the six working groups established under the Arctic Council. AMAP is tasked with monitoring the levels of contaminants present in the Arctic environment and people as well as assessing their effects on a continuous basis, and reporting these results regularly. Most of the presented data have been collected over the last 20 years and are from all eight Arctic countries. Levels of contaminants appear to be declining in some of the monitored Arctic populations, but it is not consistent across the Arctic. Most Arctic populations continue to experience elevated levels of these contaminants compared to other populations monitored globally. There are certain contaminants, such as perfluorinated compounds and polybrominated diphenyl ethers, which are still increasing in Arctic populations. These contaminants require more investigation to find out the predominant and important sources of exposure, and whether they are being transported to the Arctic through long-range transport in the environment.

Levels and trends of contaminants in humans of the Arctic

PubMed Central

Gibson, Jennifer; Adlard, Bryan; Olafsdottir, Kristin; Sandanger, Torkjel Manning; Odland, Jon Øyvind

2016-01-01

The Arctic Monitoring and Assessment Programme (AMAP) is one of the six working groups established under the Arctic Council. AMAP is tasked with monitoring the levels of contaminants present in the Arctic environment and people as well as assessing their effects on a continuous basis, and reporting these results regularly. Most of the presented data have been collected over the last 20 years and are from all eight Arctic countries. Levels of contaminants appear to be declining in some of the monitored Arctic populations, but it is not consistent across the Arctic. Most Arctic populations continue to experience elevated levels of these contaminants compared to other populations monitored globally. There are certain contaminants, such as perfluorinated compounds and polybrominated diphenyl ethers, which are still increasing in Arctic populations. These contaminants require more investigation to find out the predominant and important sources of exposure, and whether they are being transported to the Arctic through long-range transport in the environment. PMID:27974136

The Influence of Stratigraphic History on Landscape Evolution

NASA Astrophysics Data System (ADS)

Forte, A. M.; Yanites, B.; Whipple, K. X.

2016-12-01

Variation in rock erodibility can play a significant role in landscape evolution. Using a version of the CHILD landscape evolution model that allows for variations in rock erodibility, we found surprisingly complex landscape evolution in simulations with simple, two unit stratigraphies with contrasting erodibility. This work indicated that the stratigraphic order of units in terms of erodibility, the orientation of the contact with respect to the main drainage direction, and the contact dip angle all have pronounced effects on landscape evolution. Here we expand that work to explore the implications of more complicated stratigraphies on landscape evolution. Introducing multiple units adds additional controls on landscape evolution, namely the thicknesses and relative erodibility of rock layers. In models with a sequence of five alternating hard and soft units embedded within arbitrarily thick over- and underlying units, the number of individual layers that noticeably influence landscape morphology decreases as the thickness of individual layers reduces. Contacts with soft rocks over hard produce the most noticeable effect in model output such as erosion rate and channel steepness. For large contrasts in erodibility of 25 m thick layers, only one soft over hard contact is clearly manifest in the landscape. Between 50 and 75 m, two such contacts are manifest, and by 100 m thickness, all three of these contacts are manifest. However, for a given thickness of layers, more units are manifest in the landscape as the erodibility contrast between units decreases. This is true even though the magnitude of landscape effects away from steady-state erosion rates or channel steepness also decrease with decreasing erodibility contrast. Finally, we explore suites of models with alternating layers reflecting either `hardening-' or `softening-upwards' stratigraphies and find that the two scenarios result in decidedly different landscape forms. Hardening-upwards sections produce a gradational change where as individual layers have more influence in the landscape form in softening-upwards sections. Generally, our modeling highlights that past depositional history can exert a fundamental control on landscape evolution during later erosion through the resulting layered stratigraphy.

Arctic potential - Could more structured view improve the understanding of Arctic business opportunities?

NASA Astrophysics Data System (ADS)

Hintsala, Henna; Niemelä, Sami; Tervonen, Pekka

2016-09-01

The increasing interest towards the Arctic has been witnessed during the past decades. However, the commonly shared definitions of the Arctic key concepts have not yet penetrated national and international arenas for political and economic decision making. The lack of jointly defined framework has made different analyses related to the Arctic quite limited considering the magnitude of economic potential embedded in Arctic. This paper is built on the key findings of two separate, yet connected projects carried out in the Oulu region, Finland. In this paper's approach, the Arctic context has been defined as a composition of three overlapping layers. The first layer is the phenomenological approach to define the Arctic region. The second layer is the strategy-level analysis to define different Arctic paths as well as a national level description of a roadmap to Arctic specialization. The third layer is the operationalization of the first two layers to define the Arctic business context and business opportunities. The studied case from Oulu region indicates that alternative futures for the Arctic competences and business activities are in resemblance with only two of the four identified strategic pathways. Introduction of other pathways to regional level actors as credible and attractive options would require additional, systematic efforts.

Sulfate Aerosol in the Arctic: Source Attribution and Radiative Forcing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yang; Wang, Hailong; Smith, Steven J.

Source attributions of Arctic sulfate and its direct radiative effect for 2010–2014 are quantified in this study using the Community Earth System Model (CESM) equipped with an explicit sulfur source-tagging technique. Regions that have high emissions and/or are near/within the Arctic present relatively large contributions to Arctic sulfate burden, with the largest contribution from sources in East Asia (27%). East Asia and South Asia together have the largest contributions to Arctic sulfate concentrations at 9–12 km, whereas sources within or near the Arctic account largely below 2 km. For remote sources with strong emissions, their contributions to Arctic sulfate burdenmore » are primarily driven by meteorology, while contributions of sources within or near the Arctic are dominated by their emission strength. The sulfate direct radiative effect (DRE) is –0.080 W m-2 at the Arctic surface, offsetting the net warming effect from the combination of in-snow heating and DRE cooling from black carbon. East Asia, Arctic local and Russia/Belarus/Ukraine sources contribute –0.017, –0.016 and –0.014 W m-2, respectively, to Arctic sulfate DRE. A 20% reduction in anthropogenic SO2 emissions leads to a net increase of +0.013 W m-2 forcing at the Arctic surface. These results indicate that a joint reduction in BC emissions could prevent possible Arctic warming from future reductions in SO2 emissions. Sulfate DRE efficiency calculations suggest that short transport pathways together with meteorology favoring long sulfate lifetimes make certain sources more efficient in influencing the Arctic sulfate DRE.« less

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Weiqing; Meehl, Gerald A.; Stammer, Detlef

Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth’s climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modesmore » and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this article, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.« less

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

DOE PAGES

Han, Weiqing; Meehl, Gerald A.; Stammer, Detlef; ...

2016-10-04

Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth’s climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modesmore » and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this article, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.« less

Spatial Patterns of Sea Level Variability Associated with Natural Internal Climate Modes

NASA Astrophysics Data System (ADS)

Han, Weiqing; Meehl, Gerald A.; Stammer, Detlef; Hu, Aixue; Hamlington, Benjamin; Kenigson, Jessica; Palanisamy, Hindumathi; Thompson, Philip

2017-01-01

Sea level rise (SLR) can exert significant stress on highly populated coastal societies and low-lying island countries around the world. Because of this, there is huge societal demand for improved decadal predictions and future projections of SLR, particularly on a local scale along coastlines. Regionally, sea level variations can deviate considerably from the global mean due to various geophysical processes. These include changes of ocean circulations, which partially can be attributed to natural, internal modes of variability in the complex Earth's climate system. Anthropogenic influence may also contribute to regional sea level variations. Separating the effects of natural climate modes and anthropogenic forcing, however, remains a challenge and requires identification of the imprint of specific climate modes in observed sea level change patterns. In this paper, we review our current state of knowledge about spatial patterns of sea level variability associated with natural climate modes on interannual-to-multidecadal timescales, with particular focus on decadal-to-multidecadal variability. Relevant climate modes and our current state of understanding their associated sea level patterns and driving mechanisms are elaborated separately for the Pacific, the Indian, the Atlantic, and the Arctic and Southern Oceans. We also discuss the issues, challenges and future outlooks for understanding the regional sea level patterns associated with climate modes. Effects of these internal modes have to be taken into account in order to achieve more reliable near-term predictions and future projections of regional SLR.

BAID: The Barrow Area Information Database - an interactive web mapping portal and cyberinfrastructure for scientific activities in the vicinity of Barrow, Alaska

NASA Astrophysics Data System (ADS)

Cody, R. P.; Kassin, A.; Gaylord, A. G.; Tweedie, C. E.

2013-12-01

In 2013, the Barrow Area Information Database (BAID, www.baid.utep.edu) project resumed field operations in Barrow, AK. The Barrow area of northern Alaska is one of the most intensely researched locations in the Arctic. BAID is a cyberinfrastructure (CI) that details much of the historic and extant research undertaken within in the Barrow region in a suite of interactive web-based mapping and information portals (geobrowsers). The BAID user community and target audience for BAID is diverse and includes research scientists, science logisticians, land managers, educators, students, and the general public. BAID contains information on more than 11,000 Barrow area research sites that extend back to the 1940's and more than 640 remote sensing images and geospatial datasets. In a web-based setting, users can zoom, pan, query, measure distance, and save or print maps and query results. Data are described with metadata that meet Federal Geographic Data Committee standards and are archived at the University Corporation for Atmospheric Research Earth Observing Laboratory (EOL) where non-proprietary BAID data can be freely downloaded. Highlights for the 2013 season include the addition of more than 2000 additional research sites, providing differential global position system (dGPS) support to visiting scientists, surveying over 80 miles of coastline to document rates of erosion, training of local GIS personal, deployment of a wireless sensor network, and substantial upgrades to the BAID website and web mapping applications.

Fractal analysis of INSAR and correlation with graph-cut based image registration for coastline deformation analysis: post seismic hazard assessment of the 2011 Tohoku earthquake region

NASA Astrophysics Data System (ADS)

Dutta, P. K.; Mishra, O. P.

2012-04-01

Satellite imagery for 2011 earthquake off the Pacific coast of Tohoku has provided an opportunity to conduct image transformation analyses by employing multi-temporal images retrieval techniques. In this study, we used a new image segmentation algorithm to image coastline deformation by adopting graph cut energy minimization framework. Comprehensive analysis of available INSAR images using coastline deformation analysis helped extract disaster information of the affected region of the 2011 Tohoku tsunamigenic earthquake source zone. We attempted to correlate fractal analysis of seismic clustering behavior with image processing analogies and our observations suggest that increase in fractal dimension distribution is associated with clustering of events that may determine the level of devastation of the region. The implementation of graph cut based image registration technique helps us to detect the devastation across the coastline of Tohoku through change of intensity of pixels that carries out regional segmentation for the change in coastal boundary after the tsunami. The study applies transformation parameters on remotely sensed images by manually segmenting the image to recovering translation parameter from two images that differ by rotation. Based on the satellite image analysis through image segmentation, it is found that the area of 0.997 sq km for the Honshu region was a maximum damage zone localized in the coastal belt of NE Japan forearc region. The analysis helps infer using matlab that the proposed graph cut algorithm is robust and more accurate than other image registration methods. The analysis shows that the method can give a realistic estimate for recovered deformation fields in pixels corresponding to coastline change which may help formulate the strategy for assessment during post disaster need assessment scenario for the coastal belts associated with damages due to strong shaking and tsunamis in the world under disaster risk mitigation programs.

Hazard proximity and risk perception of tsunamis in coastal cities: Are people able to identify their risk?

PubMed

Arias, Juan Pablo; Bronfman, Nicolás C; Cisternas, Pamela C; Repetto, Paula B

2017-01-01

Researchers have previously reported that hazard proximity can influence risk perception among individuals exposed to potential hazards. Understanding this relationship among coastline communities at risk of flood events caused by storms and/or tsunamis, is important because hazard proximity, should be recognized when planning and implementing preparation and mitigation actions against these events. Yet, we are not aware of studies that have examined this relationship among coastline inhabitants facing the risk of a tsunami. Consequently, the aim of this study was to examine the relationship between hazard proximity and perceived risk from tsunamis among coastline inhabitants. Participants were 487 residents of the coastal city of Iquique, Chile. They completed a survey during the spring of 2013 that assessed their perceived risk from several natural and non-natural hazards. We found that hazard proximity maintains a negative relationship with the perception of tsunami risk among coastline inhabitants. While this result confirms the general trend obtained in previous studies, this one is conclusive and significant. In contradiction with previous findings, we found that participants from the highest socioeconomic status reported the highest levels of risk perception. This finding can be explained by the fact that most participants from the highest socioeconomic status live closer to the coastline areas, so their risk perception reflects the place where they live, that is in a tsunami inundation zone. Once again, hazard proximity proved to be a determinant factor of risk perception. Our findings have important implications for the development of plans and programs for tsunami preparedness and mitigation. These indicate that individuals do use environmental cues to evaluate their own risk and can potentially make correct choices when having or not to evacuate. Also suggest that preparedness should incorporate how hazard proximity is recognized by individuals and communities at risk.

Hazard proximity and risk perception of tsunamis in coastal cities: Are people able to identify their risk?

PubMed Central

Arias, Juan Pablo; Bronfman, Nicolás C.; Cisternas, Pamela C.; Repetto, Paula B.

2017-01-01

Researchers have previously reported that hazard proximity can influence risk perception among individuals exposed to potential hazards. Understanding this relationship among coastline communities at risk of flood events caused by storms and/or tsunamis, is important because hazard proximity, should be recognized when planning and implementing preparation and mitigation actions against these events. Yet, we are not aware of studies that have examined this relationship among coastline inhabitants facing the risk of a tsunami. Consequently, the aim of this study was to examine the relationship between hazard proximity and perceived risk from tsunamis among coastline inhabitants. Participants were 487 residents of the coastal city of Iquique, Chile. They completed a survey during the spring of 2013 that assessed their perceived risk from several natural and non-natural hazards. We found that hazard proximity maintains a negative relationship with the perception of tsunami risk among coastline inhabitants. While this result confirms the general trend obtained in previous studies, this one is conclusive and significant. In contradiction with previous findings, we found that participants from the highest socioeconomic status reported the highest levels of risk perception. This finding can be explained by the fact that most participants from the highest socioeconomic status live closer to the coastline areas, so their risk perception reflects the place where they live, that is in a tsunami inundation zone. Once again, hazard proximity proved to be a determinant factor of risk perception. Our findings have important implications for the development of plans and programs for tsunami preparedness and mitigation. These indicate that individuals do use environmental cues to evaluate their own risk and can potentially make correct choices when having or not to evacuate. Also suggest that preparedness should incorporate how hazard proximity is recognized by individuals and communities at risk. PMID:29088230

NATO’s Future Role in the Arctic

DTIC Science & Technology

2016-05-01

iv Global Climate Change and Arctic Geopolitics............................. Error! Bookmark not defined. Russian Claims to the Arctic...13 1 Global Climate Change and Arctic Geopolitics Global climate change has a profound...explaining the effect of climate change in the Arctic and the consequences on regional security. Issues regarding territorial sovereignty will be

Explore Arctic Health.

PubMed

Lebow, Mahria

2014-04-01

The Arctic Health web site is a portal to Arctic-specific, health related content. The site provides expertly organized and annotated resources pertinent to northern peoples and places, including health information, research publications and environmental information. This site also features the Arctic Health Publications Database, which indexes an array of Arctic-related resources.

PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways): Introduction and overview

NASA Astrophysics Data System (ADS)

Ó Cofaigh, Colm; Briner, Jason P.; Kirchner, Nina; Lucchi, Renata G.; Meyer, Hanno; Kaufman, Darrell S.

2016-09-01

This special issue relates to the Second International Conference of the PAST Gateways (Palaeo-Arctic Spatial and Temporal Gateways) network which was held in Trieste, Italy in 2014. Twenty five papers are included and they address topics under four main themes: (1) The growth and decay of Arctic ice sheets; (2) Arctic sea ice and palaeoceanography; (3) Terrestrial Arctic environments and permafrost change; and (4) Holocene Arctic environmental change. Geographically the focus is circum-Arctic; the special issue includes detailed regional studies from Greenland, Scandinavia, Russia, and Arctic North America and the adjoining seas, as well as a series of synthesis-type, review papers on Fennoscandian Ice Sheet deglaciation and Holocene Arctic palaeo-climate change. The methodologies employed are diverse and include marine sediment core and geophysical investigations, terrestrial glacial geology and geomorphology, isotopic analysis of ground ice, palaeo-ecological analysis of lacustrine and terrestrial sedimentary archives, geochronology and numerical ice sheet modeling.

Arctic Rabies – A Review

PubMed Central

Mørk, Torill; Prestrud, Pål

2004-01-01

Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies including its distribution and epidemiology. PMID:15535081

Study of Environmental Arctic Change (SEARCH): Scientific Understanding of Arctic Environmental Change to Help Society Understand and Respond to a Rapidly Changing Arctic.

NASA Astrophysics Data System (ADS)

Wiggins, H. V.; Myers, B.

2015-12-01

The Study of Environmental Arctic Change (SEARCH) is a U.S. program with a mission to provide a foundation of Arctic change science through collaboration with the research community, funding agencies, and other stakeholders. To achieve this mission, SEARCH: Generates and synthesizes research findings and promotes Arctic science and scientific discovery across disciplines and among agencies. Identifies emerging issues in Arctic environmental change. Provides scientific information to Arctic stakeholders, policy-makers, and the public to help them understand and respond to arctic environmental change. Facilitates research activities across local-to-global scales, with an emphasis on addressing needs of decision-makers. Collaborates with national and international science programs integral to SEARCH goals. This poster presentation will present SEARCH activities and plans, highlighting those focused on providing information for decision-makers. http://www.arcus.org/search

The Arctic Report Card: Communicating the State of the Rapidly Changing Arctic to a Diverse Audience via the Worldwide Web

NASA Astrophysics Data System (ADS)

Jeffries, M. O.; Richter-Menge, J.; Overland, J. E.; Soreide, N. N.

2013-12-01

Rapid change is occurring throughout the Arctic environmental system. The goal of the Arctic Report Card is to communicate the nature of the many changes to a diverse audience via the Worldwide Web. First published in 2006, the Arctic Report Card is a peer-reviewed publication containing clear, reliable and concise scientific information on the current state of the Arctic environment relative to observational records. Available only online, it is intended to be an authoritative source for scientists, teachers, students, decision-makers, policy-makers and the general public interested in the Arctic environment and science. The Arctic Report Card is organized into five sections: Atmosphere; Sea Ice & Ocean; Marine Ecosystem; Terrestrial Ecosystem; Terrestrial Cryosphere. Arctic Report Card 2012, the sixth annual update, comprised 20 essays on physical and biological topics prepared by an international team of 141 scientists from 15 different countries. For those who want a quick summary, the Arctic Report Card home page provides highlights of key events and findings, and a short video that is also available on YouTube. The release of the Report Card each autumn is preceded by a NOAA press release followed by a press conference, when the Web site is made public. The release of Arctic Report Card 2012 at an AGU Fall Meeting press conference on 5 December 2012 was subsequently reported by leading media organizations. The NOAA Arctic Web site, of which the Report Card is a part, is consistently at the top of Google search results for the keyword 'arctic', and the Arctic Report Card Web site tops search results for keyword "arctic report" - pragmatic indications of a Web site's importance and popularity. As another indication of the Web site's impact, in December 2012, the month when the 2012 update was released, the Arctic Report Card Web site was accessed by 19,851 unique sites in 105 countries, and 4765 Web site URLs referred to the Arctic Report Card. The 2012 Arctic Report Card YouTube video has been viewed 36,074 times by viewers in 152 countries and has been embedded in over two dozen Web sites. We are confident that the Arctic Report Card is succeeding in communicating the state of the rapidly changing Arctic to many people, but we need to learn more about its broader impact. Consequently, we are considering a study of how diverse an audience is being reached, and the extent to which, outside of the scientific community, the content of the Arctic Report Card is understood, is perceived as a credible, unbiased and non-threatening resource, and is overcoming prior beliefs.

Identification of in-sewer sources of organic solids contributing to combined sewer overflows.

PubMed

Ahyerre, M; Chebbo, G

2002-09-01

Previous research has shown that combined sewer systems are the main source of particle and organic pollution during rainfall events contributing to combined sewer overflow. The aim of this article is to identify in an urban catchment area called "Le Marais", in the center of Paris, the types of sediments that are eroded and contribute to the pollution of combined sewer overflow. Three sediment types are considered: granular material found in the inverts of pipes, organic biofilms and organic sediment at the water bed interface, identified as an immobile layer in the "Le Marais" catchment area. The method used consist, firstly, of sampling and assessing the organic pollutant loads and metallic loads of the particles in each type of sediment. Then, the mass of each type of sediment is assessed. The mass and the characteristics of each type of sediment is finally compared to the mass and characteristics of the particles eroded in the catchment area, estimated by mass balances, in order to find the source of eroded particles. The only identified type of deposit that can contribute to combined sewer overflows is the organic layer. Indeed, the solids of this layer have mean and metallic loads that are of the same order of magnitude as the eroded particles. Moreover, the mass of the organic layer considered over different time scales is of the same order of magnitude as the eroded masses during rainfall events and an erosion experiment showed that the organic layer is actually eroded.

Potential for an Arctic-breeding migratory bird to adjust spring migration phenology to Arctic amplification.

PubMed

Lameris, Thomas K; Scholten, Ilse; Bauer, Silke; Cobben, Marleen M P; Ens, Bruno J; Nolet, Bart A

2017-10-01

Arctic amplification, the accelerated climate warming in the polar regions, is causing a more rapid advancement of the onset of spring in the Arctic than in temperate regions. Consequently, the arrival of many migratory birds in the Arctic is thought to become increasingly mismatched with the onset of local spring, consequently reducing individual fitness and potentially even population levels. We used a dynamic state variable model to study whether Arctic long-distance migrants can advance their migratory schedules under climate warming scenarios which include Arctic amplification, and whether such an advancement is constrained by fuel accumulation or the ability to anticipate climatic changes. Our model predicts that barnacle geese Branta leucopsis suffer from considerably reduced reproductive success with increasing Arctic amplification through mistimed arrival, when they cannot anticipate a more rapid progress of Arctic spring from their wintering grounds. When geese are able to anticipate a more rapid progress of Arctic spring, they are predicted to advance their spring arrival under Arctic amplification up to 44 days without any reproductive costs in terms of optimal condition or timing of breeding. Negative effects of mistimed arrival on reproduction are predicted to be somewhat mitigated by increasing summer length under warming in the Arctic, as late arriving geese can still breed successfully. We conclude that adaptation to Arctic amplification may rather be constrained by the (un)predictability of changes in the Arctic spring than by the time available for fuel accumulation. Social migrants like geese tend to have a high behavioural plasticity regarding stopover site choice and migration schedule, giving them the potential to adapt to future climate changes on their flyway. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Climate Change, Globalization and Geopolitics in the New Maritime Arctic

NASA Astrophysics Data System (ADS)

Brigham, L. W.

2011-12-01

Early in the 21st century a confluence of climate change, globalization and geopolitics is shaping the future of the maritime Arctic. This nexus is also fostering greater linkage of the Arctic to the rest of the planet. Arctic sea ice is undergoing a historic transformation of thinning, extent reduction in all seasons, and reduction in the area of multiyear ice in the central Arctic Ocean. Global Climate Model simulations of Arctic sea ice indicate multiyear ice could disappear by 2030 for a short period of time each summer. These physical changes invite greater marine access, longer seasons of navigation, and potential, summer trans-Arctic voyages. As a result, enhanced marine safety, environmental protection, and maritime security measures are under development. Coupled with climate change as a key driver of regional change is the current and future integration of the Arctic's natural wealth with global markets (oil, gas and hard minerals). Abundant freshwater in the Arctic could also be a future commodity of value. Recent events such as drilling for hydrocarbons off Greenland's west coast and the summer marine transport of natural resources from the Russian Arctic to China across the top of Eurasia are indicators of greater global economic ties to the Arctic. Plausible Arctic futures indicate continued integration with global issues and increased complexity of a range of regional economic, security and environmental challenges.

Sensitivity of Arctic carbon in a changing climate

Treesearch

A. David McGuire; Henry P. Huntington; Simon Wilson

2009-01-01

The Arctic has been warming rapidly in the past few decades. A key question is how that warming will affect the cycling of carbon (C) in the Arctic system. At present, the Arctic is a global sink for C. If that changes and the Arctic becomes a carbon source, global climate warming may speed up.

THE US MERCURY EMISSION INVENTORY FOR THE ARCTIC COUNCIL ACTION PLAN

EPA Science Inventory

The Arctic Council, having agreed to act to reduce exposures to a number of priority pollutants in the Arctic region, has initiated a mercury project via the Arctic Council Action Plan (ACAP). The project is led by the Danish EPA with a Steering Group from all eight Arctic count...

THE US MERCURY EMISSION INVENTORY FOR THE ARCTIC COUNCIL ACTION PLAN

EPA Science Inventory

The Arctic Council, having agreed to act to reduce exposures to a number of priority pollutants in the Arctic region, has initiated a mercury project via the Arctic Council Plan (ACAP). The project is being led by the Danish EPA with a Steering Group from all eight Arctic coun...

77 FR 31677 - Request for Public Comment on Interagency Arctic Research Policy Committee (IARPC) Arctic...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-29

... OFFICE OF SCIENCE AND TECHNOLOGY POLICY Request for Public Comment on Interagency Arctic Research Policy Committee (IARPC) Arctic Research Plan: FY2013-2017 May 22, 2012. ACTION: Request for public comment. SUMMARY: The Arctic Research and Policy Act of 1984 (ARPA), Public Law 98-373, established the...

76 FR 61074 - Reports and Updates on Arctic Research Programs and Projects; Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-03

... UNITED STATES ARCTIC RESEARCH COMMISSION Reports and Updates on Arctic Research Programs and Projects; Meetings Notice is hereby given that the US Arctic Research Commission will hold its 96th meeting... about topics of interest related to research activities in the Arctic. 96th Meeting Schedule: Wed., Oct...

Children and Youth of the Arctic: A Critical Challenge of Sustainable Development.

ERIC Educational Resources Information Center

Simon, Mary

1998-01-01

Argues for a children and youth agenda as part of the Arctic Council's overall agenda, to include profiling the health of Arctic children; assessing health and developmental impacts of pollution and environmental threats on Arctic children; developing sustainable employment opportunities for Arctic youth; and expanding distance education, with a…

Ice-Free Arctic Ocean?

ERIC Educational Resources Information Center

Science Teacher, 2005

2005-01-01

The current warming trends in the Arctic may shove the Arctic system into a seasonally ice-free state not seen for more than one million years, according to a new report. The melting is accelerating, and researchers were unable to identify any natural processes that might slow the deicing of the Arctic. "What really makes the Arctic different…

Seasonal Clear-Sky Flux and Cloud Radiative Effect Anomalies in the Arctic Atmospheric Column Associated with the Arctic Oscillation and Arctic Dipole

NASA Technical Reports Server (NTRS)

Hegyi, Bradley M.; Taylor, Patrick C.

2017-01-01

The impact of the Arctic Oscillation (AO) and Arctic Dipole (AD) on the radiative flux into the Arctic mean atmospheric column is quantified. 3-month-averaged AO and AD indices are regressed with corresponding surface and top-of-atmosphere (TOA) fluxes from the CERES-SFC and CERES-TOA EBAF datasets over the period 2000-2014. An increase in clear-sky fluxes into the Arctic mean atmospheric column during fall is the largest net flux anomaly associated with AO, primarily driven by a positive net longwave flux anomaly (i.e. increase of net flux into the atmospheric column) at the surface. A decrease in the Arctic mean atmospheric column cloud radiative effect during winter and spring is the largest flux anomaly associated with AD, primarily driven by a change in the longwave cloud radiative effect at the surface. These prominent responses to AO and AD are widely distributed across the ice-covered Arctic, suggesting that the physical process or processes that bring about the flux change associated with AO and AD are distributed throughout the Arctic.

Arctic Research Plan: FY2017-2021

USGS Publications Warehouse

Starkweather, Sandy; Jeffries, Martin O; Stephenson, Simon; Anderson, Rebecca D.; Jones, Benjamin M.; Loehman, Rachel A.; von Biela, Vanessa R.

2016-01-01

The United States is an Arctic nation—Americans depend on the Arctic for biodiversity and climate regulation and for natural resources. America’s Arctic—Alaska—is at the forefront of rapid climate, environmental, and socio-economic changes that are testing the resilience and sustainability of communities and ecosystems. Research to increase fundamental understanding of these changes is needed to inform sound, science-based decision- and policy-making and to develop appropriate solutions for Alaska and the Arctic region as a whole. Created by an Act of Congress in 1984, and since 2010 a subcommittee of the National Science and Technology Council (NSTC) in the Executive Office of the President, the Interagency Arctic Research Policy Committee (IARPC) plays a critical role in advancing scientific knowledge and understanding of the changing Arctic and its impacts far beyond the boundaries of the Arctic. Comprising 14 Federal agencies, offices, and departments, IARPC is responsible for the implementation of a 5-year Arctic Research Plan in consultation with the U.S. Arctic Research Commission, the Governor of the State of Alaska, residents of the Arctic, the private sector, and public interest groups.

Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion.

PubMed

Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

2012-09-01

The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

NASA Astrophysics Data System (ADS)

Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

2012-09-01

The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

EROD activity and biliary fluorescence in Schroederichthys chilensis (Guichenot 1848): biomarkers of PAH exposure in coastal environments of the South Pacific Ocean.

PubMed

Fuentes-Rios, Daniel; Orrego, Rodrigo; Rudolph, Anny; Mendoza, Gonzalo; Gavilán, Juan F; Barra, Ricardo

2005-10-01

Schroederichthys chilensis is a common shark that lives in Chilean coastal environments. In this work, the relationship between liver 7-ethoxyresorufin-O-deethylase dealkylation (EROD) activity and Fluorescent Aromatic Compounds (FAC) in bile of S. chilensis sampled in three bays with different degrees of pollution were performed including a reference area. Sixty individuals were collected, 20 for each site; (10 males and 10 females per site) livers and bile samples were obtained and immediately frozen. EROD activity and FAC were measured according to three standard methods. EROD activity and FAC were higher in polluted areas than in the reference area. Synchronous Fluorescence Spectra of the bile from the fish collected at the most polluted area showed a peak at 347nm representing a metabolite corresponding to 1-hydroxypyrene. The low EROD activity in the reference area is likely related to the low level of PAH in sediments. We propose that this species is a good indicator of exposure to FACs, since it presents a series of characteristics that make it suitable for monitoring PAH exposure in coastal zones.

Coordinating for Arctic Conservation: Implementing Integrated Arctic Biodiversity Monitoring, Data Management and Reporting

NASA Astrophysics Data System (ADS)

Gill, M.; Svoboda, M.

2012-12-01

Arctic ecosystems and the biodiversity they support are experiencing growing pressure from various stressors (e.g. development, climate change, contaminants, etc.) while established research and monitoring programs remain largely uncoordinated, lacking the ability to effectively monitor, understand and report on biodiversity trends at the circumpolar scale. The maintenance of healthy arctic ecosystems is a global imperative as the Arctic plays a critical role in the Earth's physical, chemical and biological balance. A coordinated and comprehensive effort for monitoring arctic ecosystems is needed to facilitate effective and timely conservation and adaptation actions. The Arctic's size and complexity represents a significant challenge towards detecting and attributing important biodiversity trends. This demands a scaled, pan-arctic, ecosystem-based approach that not only identifies trends in biodiversity, but also identifies underlying causes. It is critical that this information be made available to generate effective strategies for adapting to changes now taking place in the Arctic—a process that ultimately depends on rigorous, integrated, and efficient monitoring programs that have the power to detect change within a "management" time frame. To meet these challenges and in response to the Arctic Climate Impact Assessment's recommendation to expand and enhance arctic biodiversity monitoring, the Conservation of Arctic Flora and Fauna (CAFF) Working Group of the Arctic Council launched the Circumpolar Biodiversity Monitoring Program (CBMP). The CBMP is led by Environment Canada on behalf of Canada and the Arctic Council. The CBMP is working with over 60 global partners to expand, integrate and enhance existing arctic biodiversity research and monitoring efforts to facilitate more rapid detection, communication and response to significant trends and pressures. Towards this end, the CBMP has established three Expert Monitoring Groups representing major Arctic themes (Marine, Freshwater, and Terrestrial). Each group, representing a diversity of disciplines, is tasked with developing and implementing pan-arctic integrated biodiversity monitoring plans for the Arctic's ecosystems. To facilitate effective reporting and data management, the CBMP is developing a suite of indices and indicators and a web-based data portal that will be used to report on the current state of arctic biodiversity at various scales and levels of detail to suit a wide range of audiences (e.g. local Arctic communities, regional and national governments and the Convention on Biological Diversity). The current and planned CBMP biodiversity monitoring underpins these indicators and indices. The presentation will highlight the CBMP approach and provide some examples of how integrated monitoring, data management and reporting are leading to more informed decision-making.

Stabilization of erodible slopes with geofibers and nontraditional liquid additives.

DOT National Transportation Integrated Search

2013-05-01

Instability of erodible slopes due to extreme climate events and of permafrost slopes due degradation and thawing is a significant : engineering problem for northern transportation infrastructure. Engineers continually look for mitigation alternative...

Beyond Thin Ice: Co-Communicating the Many Arctics

NASA Astrophysics Data System (ADS)

Druckenmiller, M. L.; Francis, J. A.; Huntington, H.

2015-12-01

Science communication, typically defined as informing non-expert communities of societally relevant science, is persuaded by the magnitude and pace of scientific discoveries, as well as the urgency of societal issues wherein science may inform decisions. Perhaps nowhere is the connection between these facets stronger than in the marine and coastal Arctic where environmental change is driving advancements in our understanding of natural and socio-ecological systems while paving the way for a new assortment of arctic stakeholders, who generally lack adequate operational knowledge. As such, the Arctic provides opportunity to advance the role of science communication into a collaborative process of engagement and co-communication. To date, the communication of arctic change falls within four primary genres, each with particular audiences in mind. The New Arctic communicates an arctic of new stakeholders scampering to take advantage of unprecedented access. The Global Arctic conveys the Arctic's importance to the rest of the world, primarily as a regulator of lower-latitude climate and weather. The Intra-connected Arctic emphasizes the increasing awareness of the interplay between system components, such as between sea ice loss and marine food webs. The Transforming Arctic communicates the region's trajectory relative to the historical Arctic, acknowledging the impacts on indigenous peoples. The broad societal consensus on climate change in the Arctic as compared to other regions in the world underscores the opportunity for co-communication. Seizing this opportunity requires the science community's engagement with stakeholders and indigenous peoples to construct environmental change narratives that are meaningful to climate responses relative to non-ecological priorities (e.g., infrastructure, food availability, employment, or language). Co-communication fosters opportunities for new methods of and audiences for communication, the co-production of new interdisciplinary knowledge and cross-epistemological perspectives, and direct feedback to the science community regarding the societal implications of future research. Currently, the Study for Environmental Arctic Change (SEARCH) is developing this necessary cadre of co-communicators of marine and coastal arctic change.

Recent Russian Geophysical and Geological Investigations on Siberian Continental Margin

NASA Astrophysics Data System (ADS)

P. v., A.; K. v., D.; B. v., V.

2007-12-01

In July-August, 2005 new geophysical and geological data were acquired in the Mendeleev Rise (MR) region during "Arctic-2005" cruise aboard M/V "Akademik Fedorov". The study was concentrated in the southern part of MR in the area of its junction with East Siberian shelf. On-ice deep seismic sounding investigations (with offsets up to 250 km) and helicopter-supported seismic reflection soundings were performed along 600 km-long sub- longitudinal profile. Seismic survey was accompanied by on-ice gravity observations and geological sampling. Air-borne magnetic and air gravity measurements at scale 1:1,000,000 were also performed within a 100 km- wide corridor along the central seismic profile. Processing and analysis of new evidence included the compilation of deep seismic section, 2D seismic-gravity modeling of the Earth crust, 3D modeling of basement and Moho relief, and estimation of sediment and earth crust thickness. The results were integrated with earlier data and used for advanced structural and tectonic interpretations. The following main conclusions were obtained: Thickness of sediment cover along seismic line varies from 12 km in the south (in the North-Chukchi Trough) to 3-4 km in the northern MR. Crust thickness beneath MR is on the order of 30-35 km with a maximum value of 38 km in its southern part. The thinnest crust (28 km) is observed in the North-Chukchi Trough. Potential fields indicate existence of several blocks differing in gravity and magnetic anomalies. In the southern MR these blocks appear separated by grabens and display distinct continental characteristics accentuated by thickness of the crust, its seismic velocities and potential field pattern. At some of the shallowest (possibly eroded?) bathymetric highs the results of bottom sampling seem to point to the possibility of local derivation of coarse bottom debris. The proposed tectonic model implies structural continuity between MR and the adjacent East Siberian shelf. Brief information about the latest Russian geophysical and geological cruise "Arctic-2007" to the Lomonosov Ridge and its transition to the Siberian shelf will also be presented.

The Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Wiggins, H. V.; Warnick, W. K.

2008-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi- agency Study of Environmental Arctic Change (SEARCH) program, providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS" central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include, among many others, the Witness the Arctic newsletter, the Arctic Visiting Speakers" Series, the ArcticInfo listserve, the Internet Media Archive (IMA), and the annual Arctic Forum conference. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

The Arctic Research Consortium of the United States

NASA Astrophysics Data System (ADS)

Warnick, W. K.; Wiggins, H. V.

2007-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broad science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi-agency Study of Environmental Arctic Change (SEARCH) program and providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS' central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include the Witness the Arctic newsletter, the Arctic Visiting Speakers' Series, the ArcticInfo listserve, the Internet Media Archive (IMA), the annual Arctic Forum conference, and many others. More information about these and other ARCUS activities can be found at the ARCUS website at www.arcus.org.

The Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Creek, K. R.; Fox, S. E.; Wiggins, H. V.

2010-12-01

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi-agency Study of Environmental Arctic Change (SEARCH) program, providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS’ central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include, among many others, the Witness the Arctic newsletter, the Arctic Visiting Speakers’ Series, the ArcticInfo listserve, the Internet Media Archive (IMA), and the annual Arctic Forum conference. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Connecting Arctic Research Across Boundaries through the Arctic Research Consortium of the United States (ARCUS)

NASA Astrophysics Data System (ADS)

Rich, R. H.; Myers, B.; Wiggins, H. V.; Zolkos, J.

2017-12-01

The complexities inherent in Arctic research demand a unique focus on making connections across the boundaries of discipline, institution, sector, geography, knowledge system, and culture. Since 1988, ARCUS has been working to bridge these gaps through communication, coordination, and collaboration. Recently, we have worked with partners to create a synthesis of the Arctic system, to explore the connectivity across the Arctic research community and how to strengthen it, to enable the community to have an effective voice in research funding policy, to implement a system for Arctic research community knowledge management, to bridge between global Sea Ice Prediction Network researchers and the science needs of coastal Alaska communities through the Sea Ice for Walrus Outlook, to strengthen ties between Polar researchers and educators, and to provide essential intangible infrastructure that enables cost-effective and productive research across boundaries. Employing expertise in managing for collaboration and interdisciplinarity, ARCUS complements and enables the work of its members, who constitute the Arctic research community and its key stakeholders. As a member-driven organization, everything that ARCUS does is achieved through partnership, with strong volunteer leadership of each activity. Key organizational partners in the United States include the U.S. Arctic Research Commission, Interagency Arctic Research Policy Committee, National Academy of Sciences Polar Research Board, and the North Slope Science Initiative. Internationally, ARCUS maintains strong bilateral connections with similarly focused groups in each Arctic country (and those interested in the Arctic), as well as with multinational organizations including the International Arctic Science Committee, the Association of Polar Early Career Educators, the University of the Arctic, and the Arctic Institute of North America. Currently, ARCUS is applying the best practices of the science of team science, expanding awareness of Arctic research in Washington, DC and in Alaska, and working to expand the base of support for Arctic research during this time of challenged U.S. federal research funding. The presentation will highlight our latest work to promote synthesis and systems thinking and make valuable connections.

Earth Observations taken by the Expedition 10 crew

NASA Image and Video Library

2005-01-14

ISS010-E-13079 (15 January 2005) --- Tsunami damage, northwestern Sumatra (Indonesia) is featured in this image photographed by an Expedition 10 crewmember on the International Space Station (ISS). On December 26, 2004 a large (magnitude 9.0) earthquake occurred off the western coast of Sumatra in the Indian Ocean. Scientists believe the earthquake was caused by the release of stresses accumulated as the India tectonic plate is overridden by the Burma tectonic plate. Movement of the seafloor due to the earthquake generated a tsunami, or seismic sea wave, that affected coastal regions around the Indian Ocean. The northwestern Sumatra coastline in particular suffered extensive damage and loss of life. This photo, along with image ISS010-E-13088, illustrates damage along the southwestern coast of Aceh Province in the vicinity of the city of Lho’ Kruet, Indonesia. Large areas of bare and disturbed soil (brownish gray) previously covered with vegetation are visible along the coastline. Embayments in the coastline were particularly hard hit, while adjacent headlands were less affected.

Geolocation and Pointing Accuracy Analysis for the WindSat Sensor

NASA Technical Reports Server (NTRS)

Meissner, Thomas; Wentz, Frank J.; Purdy, William E.; Gaiser, Peter W.; Poe, Gene; Uliana, Enzo A.

2006-01-01

Geolocation and pointing accuracy analyses of the WindSat flight data are presented. The two topics were intertwined in the flight data analysis and will be addressed together. WindSat has no unusual geolocation requirements relative to other sensors, but its beam pointing knowledge accuracy is especially critical to support accurate polarimetric radiometry. Pointing accuracy was improved and verified using geolocation analysis in conjunction with scan bias analysis. nvo methods were needed to properly identify and differentiate between data time tagging and pointing knowledge errors. Matchups comparing coastlines indicated in imagery data with their known geographic locations were used to identify geolocation errors. These coastline matchups showed possible pointing errors with ambiguities as to the true source of the errors. Scan bias analysis of U, the third Stokes parameter, and of vertical and horizontal polarizations provided measurement of pointing offsets resolving ambiguities in the coastline matchup analysis. Several geolocation and pointing bias sources were incfementally eliminated resulting in pointing knowledge and geolocation accuracy that met all design requirements.

Shallow rocky nursery habitat for fish: Spatial variability of juvenile fishes among this poorly protected essential habitat.

PubMed

Cheminée, Adrien; Rider, Mary; Lenfant, Philippe; Zawadzki, Audrey; Mercière, Alexandre; Crec'hriou, Romain; Mercader, Manon; Saragoni, Gilles; Neveu, Reda; Ternon, Quentin; Pastor, Jérémy

2017-06-15

Coastal nursery habitats are essential for the renewal of adult fish populations. We quantified the availability of a coastal nursery habitat (shallow heterogeneous rocky bottoms) and the spatial variability of its juvenile fish populations along 250km of the Catalan coastline (France and Spain). Nurseries were present in 27% of the coastline, but only 2% of them benefited from strict protection status. For nine taxa characteristic of this habitat, total juvenile densities varied significantly between nursery sites along the coastline, with the highest densities being found on the northern sites. Recruitment level (i.e. a proxy of nursery value) was not explained by protection level, but it was moderately and positively correlated with an anthropization index. Patterns of spatial variations were taxa-specific. Exceptional observations of four juveniles of the protected grouper Epinephelus marginatus were recorded. Our data on habitat availability and recruitment levels provides important informations which help to focus MPA management efforts. Copyright © 2017 Elsevier Ltd. All rights reserved.

A quantitative analysis of microplastic pollution along the south-eastern coastline of South Africa.

PubMed

Nel, H A; Froneman, P W

2015-12-15

The extent of microplastic pollution (<5mm) in the southern hemisphere, particularly southern Africa, is largely unknown. This study aimed to evaluate microplastic pollution along the south-eastern coastline of South Africa, looking at whether bays are characterised by higher microplastic densities than open stretches of coastline in both beach sediment and surf-zone water. Microplastic (mean ± standard error) densities in the beach sediment ranged between 688.9 ± 348.2 and 3308 ± 1449 particles · m(-2), while those in the water column varied between 257.9 ± 53.36 and 1215 ± 276.7 particles · m(-3). With few exceptions there were no significant spatial patterns in either the sediment or water column microplastic densities; with little differences in density between bays and the open coast (P>0.05). These data indicate that the presence of microplastics were not associated with proximity to land-based sources or population density, but rather is governed by water circulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

TOLERANCE TIME OF EXPERIMENTAL THERMAL PAIN (COLD INDUCED) IN VOLUNTEERS.

PubMed

Vaid, V N; Wilkhoo, N S; Jain, A K

1998-10-01

Perception of thermal pain (cold induced) was studied in 106 volunteers from troops and civilians deployed in J & K. Thermal stimulus devised was "holding ice". Tolerance time of holding ice was taken to be a measure of thermal sensitivity, volunteers were classified based on their native areas, addiction habits and socio-economic status, out of 106 volunteers, 81 could & 25 could not hold ice over 10 min. Sixteen out of 40 from coastline States and 9 out of 66 from non-coast line States failed to hold ice over 10 min. In "below average" "average" and "high average" socio-economic groups, three out of 27, 19 out of 73 and 03 out of 6 failed to hold ice over 10 min respectively. Fifteen out of 64 from "addiction habit group" and 10 out of 42 from "no addiction habit group" failed to hold ice over 10 min. Statistically no classification used in the study revealed significant difference in "tolerance times" of volunteers except the one based on coastline and non-coastline States.

Redefining U.S. Arctic Strategy

DTIC Science & Technology

2015-05-15

responsibility shifts 21 Barno, David and Nora Bensahel. The Anti-Access Challenge you’re not thinking...International Affairs 85, no. 6 (2009). 38 Barno, David and Nora Bensahel. THE ANTI-ACCESS CHALLENGE YOU’RE NOT THINKING ABOUT, 05 May 2015...and Rescue in the Arctic, 22 June 2011. Arctic Council Secretariat. About the Arctic Council, Arctic Council, 2011. Barno, David and Nora

Quaternary geomorphology and modern coastal development in response to an inherent geologic framework: An example from Charleston, South Carolina

USGS Publications Warehouse

Harris, M.S.; Gayes, P.T.; Kindinger, J.L.; Flocks, J.G.; Krantz, D.E.; Donovan, P.

2005-01-01

Coastal landscapes evolve over wide-ranging spatial and temporal scales in response to physical and biological pro-cesses that interact with a wide range of variables. To develop better predictive models for these dynamic areas, we must understand the influence of these variables on coastal morphologies and ultimately how they influence coastal processes. This study defines the influence of geologic framework variability on a classic mixed-energy coastline, and establishes four categorical scales of spatial and temporal influence on the coastal system. The near-surface, geologic framework was delineated using high-resolution seismic profiles, shallow vibracores, detailed geomorphic maps, historical shorelines, aerial photographs, and existing studies, and compared to the long- and short-term development of two coastal compartments near Charleston, South Carolina. Although it is clear that the imprint of a mixed-energy tidal and wave signal (basin-scale) dictates formation of drumstick barriers and that immediate responses to wave climate are dramatic, island size, position, and longer-term dynamics are influenced by a series of inherent, complex near-surface stratigraphic geometries. Major near-surface Tertiary geometries influence inlet placement and drainage development (island-scale) through multiple interglacial cycles and overall channel morphology (local-scale). During the modern marine transgression, the halo of ebb-tidal deltas greatly influence inlet region dynamics, while truncated beach ridges and exposed, differentially erodable Cenozoic deposits in the active system influence historical shoreline dynamics and active shoreface morphologies (blockscale). This study concludes that the mixed-energy imprint of wave and tide theories dominates general coastal morphology, but that underlying stratigraphic influences on the coast provide site-specific, long-standing imprints on coastal evolution.

Wave Runup on a Frozen Beach Under High Energy Conditions

NASA Astrophysics Data System (ADS)

Didier, D.; Bernatchez, P.; Dumont, D.; Corriveau, M.

2017-12-01

High and mid-latitude beaches have typical morphological characteristics influenced by nearshore processes prevailing under ice conditions during cold season. Nearshore ice complexes (NIC) offer a natural coastal protection by covering beach sediments, while offshore ice-infested waters dissipate incoming waves. Climate change contributes to sea ice shrinking therefore reducing its protection against erosion and flooding. In the Estuary and Gulf of the St. Lawrence (ESL, GSL) (eastern Canada), sea ice cover undergoes an overall shrinking and simulated future projections tend toward a negligible effect on wave climate by 2100. Quantifying the effect of nearshore dynamics on frozen beaches is therefore imperative for coastal management as more wave energy at the coast is expected in the future. To measure the effect of a frozen beach on wave runup elevations, this study employs a continuous video recording of the swash motion at 4Hz. Video-derived wave runup statistics have been extracted during a tidal cycle on a frozen beach, using the Pointe-Lebel beach (ESL) as a test case. Timestack analysis was combined with offshore water levels and wave measurements. A comparison of runup under icy conditions (Dec. 30 2016) with a runup distribution during summer was made under similar high energy wave conditions. Results indicate high runup excursions potentially caused by lowered sediment permeability due to high pore-ice saturation in the swash zone, accentuating the overwash of the eroding coastline and thus the risk of flooding. With projected reduction in coastal sea ice cover and thus higher wave energy, this study suggests that episodes of degradation and weakening could influence the coastal flood risk in mid- and high-latitude cold environments.

Paleovalley fills: Trunk vs. tributary

USGS Publications Warehouse

Kvale, E.P.; Archer, A.W.

2007-01-01

A late Mississippian-early Pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the Illinois Basin in the eastern United States. This drainage system was filled during the early part of the Pennsylvanian. Distinct differences can be recognized between the trunk and tributary paleovalley fills. Fills preserved within the trunk systems tend to be fluvially dominated and consist of bed-load deposits of coarse- to medium-grained sandstone and conglomerate. Conversely, the incised valleys of tributary systems tend to be filled with dark mudstone, thinly interbedded sandstones, and mudstones and siltstones. These finer grained facies exhibit marine influences manifested by tidal rhythmites, certain traces fossils, and macro- and microfauna. Examples of tributary and trunk systems, separated by no more than 7 km (4.3 mi) along strike, exhibit these styles of highly contrasting fills. Useful analogs for understanding this Pennsylvanian system include the Quaternary glacial sluiceways present in the lower Ohio, White, and Wabash river valleys of Indiana (United States) and the modern Amazon River (Brazil). Both the Amazon River and the Quaternary rivers of Indiana have (or had) trunk rivers that are (were) dominated by large quantities of bed load relative to their tributaries. The trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys, which evolved into lakes because depositional rates along the trunk are (were) so high that the mouths of the tributaries have been dammed by bed-load deposits. These Holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

Long-term environmental and health implications of morphological change and sediment transport with respect to contaminants

NASA Astrophysics Data System (ADS)

Sneddon, Christopher; Copplestone, David; Tyler, Andrew; Hunter, Peter; Smith, Nick

2014-05-01

The EPSRC-funded Adaptation and Resilience of Coastal Energy Supply (ARCoES) project encompasses four research strands, involving 14 institutions and six PhD studentships. ARCoES aims to determine the threats posed to future energy generation and the distribution network by flooding and erosion, changing patterns of coastal sedimentation, water temperature and the distribution of plants and animals in the coastal zone. Whilst this research has direct benefits for the operation of coastal power stations, ARCoES aims to have a wider stakeholder engagement through assessing how the resilience of coastal communities may be altered by five hundred years of coastal evolution. Coastal evolution will have substantial implications for the energy sector of the North West of England as former waste storage sites are eroded and remobilised within the intertidal environment. The current intertidal environmental stores of radioactivity will also experience reworking as ocean chemistry changes and saltmarsh chronologies are reworked in response to rising sea levels. There is a duel requirement to understand mass sediment movement along the North West coast of England as understanding the sediment transport dynamics is key to modelling long term coastal change and understanding how the environmental store of radioactivity will be reworked. The University of Stirling is researching the long-term environmental and health implications of remobilisation and transport of contaminated sediments around the UK coastline. Using a synergy of hyperspectral and topographic information the mobilisation of sediment bound contaminants within the coastal environment will be investigated. Potential hazards posed by contaminants are determined by a set of environmental impact test criteria which evaluate the bio-accessibility and ionising dose of contaminants. These test criteria will be used to comment on the likely environmental impact of modelled sediment transport and anticipated changes in ocean chemistry.

Identification of Radar Facies and Linked Process-Based Palaeo-environmental Interpretations, Cooloola Sand Mass, Queensland, Australia

NASA Astrophysics Data System (ADS)

Gontz, A. M.; McCallum, A. B.; Moss, P. T.; Shulmeister, J.

2015-12-01

During 2015 and 2014, nearly 60 km of high-resolution ground penetrating radar data were acquired on the Cooloola Sand Mass (CSM) in southeastern coastal Queensland. The CSM is part of the world's largest downdrift sand system. It contains three of the world's largest sand islands, several National Parks, a UNESCO World Heritage Site and covers 500 km of the eastern Australian coastline in northern New South Wales and southern Queensland. The large (>200 m) composite dunes of the CSM exhibit multiple activation phases, coastally eroding bluffs and dune development is not obvious from surficial exposures. This provides an ideal environment for ground penetrating radar. The dune sequences have been provisionally dated to the mid Quaternary through present and represent the potential for a large palaeo-environmental proxy dataset. GPR imagery was collected using a MALA GeoSciences Ground Explorer (GX) system with 160 and 450 MHz antennae from the numerous physiographic and ecological provinces as well as mapped surficial soil units at the CSM. These data were used to determine the subsurface architecture, identify radar facies and develop environmental interpretations. In the clean, aeolian quartz-rich sands, radar wave penetration exceeded 30 m (radar velocity = 0.07 m/ns) with the 160 MHz antenna. From the interpreted environmental units including palaeosol, dune slip face, dune stoss face, sand blow, beach, estuarine and fluvial, we are developing maps to relate the units and focus a detailed sampling regime that includes OSL, sediment geochemistry and sedimentology, The interpreted units, stratigraphic correlation and spatial distribution of the facies is the first step in a broader project to unravel the Quaternary environmental and climate records that are archived within the sediments of the CSM.

Growth, Uplift and Truncation of Indo-Burman Anticlines Paced By Glacial-Interglacial Sea Level Change

NASA Astrophysics Data System (ADS)

Gale, J.; Steckler, M. S.; Sousa, D.; Seeber, L.; Goodbred, S. L., Jr.; Ferguson, E. K.

2014-12-01

The Ganges-Brahmaputra Delta abuts the Indo-Burman Arc on the east. Subduction of the thick delta strata has generated a large subaerial accretionary prism, up to 250 km wide, with multiple ranges of anticlines composed of the folded and faulted delta sediments. As the wedge has grown, the exposed anticlines have become subject to erosion by the rivers draining the Himalaya, a local Indo-Burman drainage network, and coastal processes. Multiple lines of geophysical, geologic, and geomorphologic evidence indicate anticline truncation as a result of interaction with the rivers of the delta and sea level. Seismic lines, geologic mapping, and geomorphology reveal truncated anticlines with angular unconformities that have been arched due to continued growth of the anticline. Buried, truncated anticlines have been identified by seismic lines, tube well logs, and resistivity measurements. The truncation of these anticlines also appears to provide a pathway for high-As Holocene groundwater into the generally low-As Pleistocene groundwater. Overall, the distribution of anticline erosion and elevation in the fold belt appears to be consistent with glacial-interglacial changes in river behavior in the delta. The anticline crests are eroded during sea level highstands as rivers and the coastline sweep across the region, and excavated by local drainage during lowstands. With continued growth, the anticlines are uplifted above the delta and "survive" as topographic features. As a result, the maximum elevations of the anticlines are clustered in a pattern suggesting continued growth since their last glacial highstand truncation. An uplift rate is calculated from this paced truncation and growth that is consistent with other measurements of Indo-Burman wedge advance. This rate, combined with the proposed method of truncation, give further evidence of dynamic fluvial changes in the delta between glacial and interglacial times.

Volcanic complexes in the eastern ridge of the Canary Islands: the Miocene activity of the island of Fuerteventura

NASA Astrophysics Data System (ADS)

Ancochea, E.; Brändle, J. L.; Cubas, C. R.; Hernán, F.; Huertas, M. J.

1996-03-01

Fuerteventura has been since early stages of its growth the result of three different adjacent large volcanic complexes: Southern, Central and Northern. The definition of these volcanic complexes and their respective growing episodes is based on volcano-stratigraphic, morphological and structural criteria, particularly radial dyke swarms. Each complex has its own prolonged history that might be longer than 10 m.y. During that time, several periods of activity alternating with gaps accompanied by important erosion took place. The evolution of each volcanic complex has been partially independent but all the three are affected by at least three Miocene tectonic phases that controlled considerably their activity. The volcanic complexes are deeply eroded and partially submerged. In the core of the Northern and the Central volcanic complexes there is a set of submarine and plutonic rocks intensely traversed by a dyke swarm, known as the Basal Complex. The Basal Complex has been interpreted in different ways but all previous authors have considered it to be prior to the subaerial shield stage of the island. Here we advance the idea that the Basal Complex represent the submarine growing stage of the volcanic complexes and the hypabyssal roots (plutons and dykes) of their successive subaerial growing episodes. Two seamounts situated nearby, southwest of the island, might be interpreted as remains of two other major volcanoes. These two volcanoes, together with those forming the present emerged island of Fuerteventura, and finally those of Famara and Los Ajaches situated further north on Lanzarote constitute a chain of volcanoes located along a lineation which is subparallel to the northwestern African coastline and which may relate to early Atlantic spreading trends in the area.

The Younger Dryas Main Line on Leka, Norway, as determined from a high resolution digital elevation model derived from airborne LiDAR data

NASA Astrophysics Data System (ADS)

Høgaas, Fredrik; Sveian, Harald

2015-02-01

The Main Line is a conspicuous late glacial erosive feature along parts of the Norwegian coastline. Although the shoreline has been much studied, the genesis of the ancient raised sea-level is still somewhat unaccounted for. In this study, the Main Line on Leka, Norway, is illuminated through a high resolution (1 m pixel size) digital elevation model (DEM) derived from airborne LiDAR data. The DEM allows a detailed mapping of the shoreline's dimensions and actual distribution and hence provides an improved foundation for interpreting the pronounced features. A new method for estimating cliff degradation during shoreline formation is presented. The Main Line is found from 106-112 m asl on Leka. Varying platform morphology across the island points to different shore-eroding mechanisms. The shoreline is thought to be developed through the interaction of sea-ice processes and freeze-thaw mechanisms, where the former agent is considered to be of particular importance where the platforms are most levelled. A bulge on the outermost part of the shoreline features is described for the first time and interpreted as a consequence of freeze-on plucking. Mean platform widths range from 9-29 m, while mean cliff degradation is estimated to be 140 m3 m- 1. By adapting the age span of Main Line formation reported elsewhere, maximum erosion rates over 1 Ma totals to 58 km. The study sheds light on the Main Line's potential as a reference level when assessing postglacial landscape development and highlights the significance of episodic erosional events in cold climate regimes.

Rates and trends of coastal change in california and the regional behavior of the beach and cliff system

USGS Publications Warehouse

Hapke, C.J.; Reid, Don; Richmond, B.

2009-01-01

The U.S. Geological Survey (USGS) recently completed an analysis of shoreline change and cliff retreat along the California coast. This is the first regional, systematic measurement of coastal change conducted for the West Coast. Long-term (-120 y) and short-term (-25 y) shoreline change rates were calculated for more than 750 km of coastline, and 70 year cliff-retreat rates were generated for 350 km of coast. Results show that 40% of California's beaches were eroding in the long term. This number increased to 66% in the short term, indicating that many beaches have shifted toward a state of chronic erosion. The statewide average net shoreline change rates for the long and short term were 0.2 m/y and -0.2 m/y, respectively. The long-term accretional signal is likely related to large coastal engineering projects in some parts of the state and to large fluxes of sediment from rivers in other areas. The cliff-retreat assessment yielded a statewide average of -0.3 m/y. It was found that Northern California has the highest overall retreat rates, which are influenced by erosion hot spots associated with large coastal landslides and slumps. The databases established as part of the shoreline change and cliff-retreat analyses were further investigated to examine the dynamics of the beach/cliff system. A correlation analysis identified a strong relationship between the geomorphology of the coast and the behavior of the beach/cliff system. Areas of high-relief coast show negative correlations, indicating that higher rates of cliff retreat correlate with lower rates of shoreline erosion. In contrast, low- to moderate-relief coasts show strong positive correlations, wherein areas of high shoreline change correspond to areas of high cliff retreat.

Mapping Eroded Areas on Mountain Grassland with Terrestrial Photogrammetry and Object-Based Image Analysis

NASA Astrophysics Data System (ADS)

Mayr, Andreas; Rutzinger, Martin; Bremer, Magnus; Geitner, Clemens

2016-06-01

In the Alps as well as in other mountain regions steep grassland is frequently affected by shallow erosion. Often small landslides or snow movements displace the vegetation together with soil and/or unconsolidated material. This results in bare earth surface patches within the grass covered slope. Close-range and remote sensing techniques are promising for both mapping and monitoring these eroded areas. This is essential for a better geomorphological process understanding, to assess past and recent developments, and to plan mitigation measures. Recent developments in image matching techniques make it feasible to produce high resolution orthophotos and digital elevation models from terrestrial oblique images. In this paper we propose to delineate the boundary of eroded areas for selected scenes of a study area, using close-range photogrammetric data. Striving for an efficient, objective and reproducible workflow for this task, we developed an approach for automated classification of the scenes into the classes grass and eroded. We propose an object-based image analysis (OBIA) workflow which consists of image segmentation and automated threshold selection for classification using the Excess Green Vegetation Index (ExG). The automated workflow is tested with ten different scenes. Compared to a manual classification, grass and eroded areas are classified with an overall accuracy between 90.7% and 95.5%, depending on the scene. The methods proved to be insensitive to differences in illumination of the scenes and greenness of the grass. The proposed workflow reduces user interaction and is transferable to other study areas. We conclude that close-range photogrammetry is a valuable low-cost tool for mapping this type of eroded areas in the field with a high level of detail and quality. In future, the output will be used as ground truth for an area-wide mapping of eroded areas in coarser resolution aerial orthophotos acquired at the same time.

The Climate Science Special Report: Arctic Changes and their Effect on Alaska and the Rest of the United States

NASA Astrophysics Data System (ADS)

Taylor, P. C.

2017-12-01

Rapid and visible climate change is happening across the Arctic, outpacing global change. Annual average near-surface air temperatures across the Arctic are increasing at more than twice the rate of global average surface temperature. In addition to surface temperature, all components of the Arctic climate system are responding in kind, including sea ice, mountain glaciers and the Greenland Ice sheet, snow cover, and permafrost. Many of these changes with a discernable anthropogenic imprint. While Arctic climate change may seem physically remote to those living in other regions of the planet, Arctic climate change can affect the global climate influencing sea level, the carbon cycle, and potentially atmospheric and oceanic circulation patterns. As an Arctic nation, United States' adaptation, mitigation, and policy decisions depend on projections of future Alaskan and Arctic climate. This chapter of the Climate Science Special Report documents significant scientific progress and knowledge about how the Alaskan and Arctic climate has changed and will continue to change.

A quantitative assessment of Arctic shipping in 2010–2014

PubMed Central

Eguíluz, Victor M.; Fernández-Gracia, Juan; Irigoien, Xabier; Duarte, Carlos M.

2016-01-01

Rapid loss of sea ice is opening up the Arctic Ocean to shipping, a practice that is forecasted to increase rapidly by 2050 when many models predict that the Arctic Ocean will largely be free of ice toward the end of summer. These forecasts carry considerable uncertainty because Arctic shipping was previously considered too sparse to allow for adequate validation. Here, we provide quantitative evidence that the extent of Arctic shipping in the period 2011–2014 is already significant and that it is concentrated (i) in the Norwegian and Barents Seas, and (ii) predominantly accessed via the Northeast and Northwest Passages. Thick ice along the forecasted direct trans-Arctic route was still present in 2014, preventing transit. Although Arctic shipping remains constrained by the extent of ice coverage, during every September, this coverage is at a minimum, allowing the highest levels of shipping activity. Access to Arctic resources, particularly fisheries, is the most important driver of Arctic shipping thus far. PMID:27477878

Implementation of the century ecosystem model for an eroding hillslope in Mississippi

USGS Publications Warehouse

Sharpe, Jodie; Harden, Jennifer W.; Dabney, Seth M.; Ojima, Dennis; Parton, William

1998-01-01

The objective of this study was to parameterize and implement the Century ecosystem model for an eroding, cultivated site near Senatobia, in Panola County, Mississippi, in order to understand the loss and replacement of soil organic carbon on an eroding cropland. The sites chosen for this study are located on highly eroded loess soils where USDA has conducted studies on rates of soil erosion. We used USDA sediment data from the study site and historical erosion estimates from the nearby area as model input for soil loss; in addition, inputs for parametization include particle-size data, climate data, and rainfall/runoff data that were collected and reported in companion papers. A cropping scenario was implemented to simulate a research site at the USDA watershed 2 at the Nelson Farm. Model output was compiled for comparison with data collected and reported in companion reports; interpretive comparisons are reported in Harden et al, in press.

Surface properties of beached plastics.

PubMed

Fotopoulou, Kalliopi N; Karapanagioti, Hrissi K

2015-07-01

Studying plastic characteristics in the marine environment is important to better understand interaction between plastics and the environment. In the present study, high-density polyethylene (HDPE), polyethylene terephalate (PET), and polyvinyl chloride (PVC) samples were collected from the coastal environment in order to study their surface properties. Surface properties such as surface functional groups, surface topography, point of zero charge, and color change are important factors that change during degradation. Eroded HDPE demonstrated an altered surface topography and color and new functional groups. Eroded PET surface was uneven, yellow, and occasionally, colonized by microbes. A decrease in Fourier transform infrared (FTIR) peaks was observed for eroded PET suggesting that degradation had occurred. For eroded PVC, its surface became more lamellar and a new FTIR peak was observed. These surface properties were obtained due to degradation and could be used to explain the interaction between plastics, microbes, and pollutants.

SEARCH: Study of Environmental Arctic Change-A System-scale, Cross-disciplinary Arctic Research Program

NASA Astrophysics Data System (ADS)

Wiggins, H. V.; Eicken, H.; Fox, S. E.; Search Science Steering Committee

2011-12-01

SEARCH is an interdisciplinary and interagency program that works with academic and government agency scientists to plan, conduct, and synthesize studies of arctic change. The vision of SEARCH is to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. Towards this end, SEARCH: (1) Generates and synthesizes research findings and promotes arctic science and scientific discovery across disciplines and among agencies. (2) Identifies emerging issues in arctic environmental change. (3) Provides information resources to arctic stakeholders, policy-makers, and the public to help them respond to arctic environmental change. (4) Coordinates with national arctic science programs integral to SEARCH goals. (5) Facilitates research activities across local-to-global scales with stakeholder concerns incorporated from the start of the planning process. (6) Represents the U.S. arctic environmental change science community in international and global change research initiatives. Examples of specific SEARCH activities include: (1) Arctic Observing Network (AON) - a system of atmospheric, land- and ocean-based environmental monitoring capabilities that will significantly advance our observations of arctic environmental conditions. (2) Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. (3) Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. (4) Developing recommendations for an interagency "Understanding Arctic Change" program. In addition to the above activities, SEARCH is also currently undertaking a strategic planning process to define priority goals and objectives for the next 3-5 years. SEARCH is guided by a Science Steering Committee and several panels and working groups, with broad representation of the research community. SEARCH is sponsored by eight U.S. agencies, including: the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA), the Department of Defense (DOD), the Department of Energy (DOE), the Department of the Interior (DOI), the Smithsonian Institution, and the U.S. Department of Agriculture (USDA). The U.S. Arctic Research Commission participates as an agency observer. For further information, please visit the website: http://www.arcus.org/search or contact: Helen V. Wiggins: helen@arcus.org, SEARCH Project Office, Arctic Research Consortium of the U.S. (ARCUS).

Arctic: A Friend Acting Strangely

Science.gov Websites

frequent. Explore the Arctic's changing climate. Discover what these changes mean for the Arctic, its warming in the Arctic by exploring how changes have been observed and documented by scientists and polar

Connecting Ocean Heat Transport Changes from the Midlatitudes to the Arctic Ocean

NASA Astrophysics Data System (ADS)

Hezel, P.; Nummelin, A.; Li, C.

2017-12-01

Under greenhouse warming, climate models simulate a weakening of the Atlantic Meridional Overturning Circulation and the associated ocean heat transport at midlatitudes but an increase in the ocean heat transport to the Arctic Ocean. These opposing trends lead to what could appear to be a discrepancy in the reported ocean contribution to Arctic amplification. This study clarifies how ocean heat transport affects Arctic climate under strong greenhouse warming using a set of the 21st century simulations performed within the Coupled Model Intercomparison Project. The results suggest that a future reduction in subpolar ocean heat loss enhances ocean heat transport to the Arctic Ocean, driving an increase in Arctic Ocean heat content and contributing to the intermodel spread in Arctic amplification. The results caution against extrapolating the forced oceanic signal from the midlatitudes to the Arctic.

Arctic climate tipping points.

PubMed

Lenton, Timothy M

2012-02-01

There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points.

Arctic Research NASA's Cryospheric Sciences Program

NASA Technical Reports Server (NTRS)

Waleed, Abdalati; Zukor, Dorothy J. (Technical Monitor)

2001-01-01

Much of NASA's Arctic Research is run through its Cryospheric Sciences Program. Arctic research efforts to date have focused primarily on investigations of the mass balance of the largest Arctic land-ice masses and the mechanisms that control it, interactions among sea ice, polar oceans, and the polar atmosphere, atmospheric processes in the polar regions, energy exchanges in the Arctic. All of these efforts have been focused on characterizing, understanding, and predicting, changes in the Arctic. NASA's unique vantage from space provides an important perspective for the study of these large scale processes, while detailed process information is obtained through targeted in situ field and airborne campaigns and models. An overview of NASA investigations in the Arctic will be presented demonstrating how the synthesis of space-based technology, and these complementary components have advanced our understanding of physical processes in the Arctic.

Promoting Knowledge to Action through the Study of Environmental Arctic Change (SEARCH) Program

NASA Astrophysics Data System (ADS)

Myers, B.; Wiggins, H. V.

2016-12-01

The Study of Environmental Arctic Change (SEARCH) is a multi-institutional collaborative U.S. program that advances scientific knowledge to inform societal responses to Arctic change. Currently, SEARCH focuses on how diminishing Arctic sea ice, thawing permafrost, and shrinking land ice impact both Arctic and global systems. Emphasizing "knowledge to action", SEARCH promotes collaborative research, synthesizes research findings, and broadly communicates the resulting knowledge to Arctic researchers, stakeholders, policy-makers, and the public. This poster presentation will highlight recent program products and findings; best practices and challenges for managing a distributed, interdisciplinary program; and plans for cross-disciplinary working groups focused on Arctic coastal erosion, synthesis of methane budgets, and development of Arctic scenarios. A specific focus will include how members of the broader research community can participate in SEARCH activities. http://www.arcus.org/search

Traditional Aids to Navigation: The Next 25 Years

NASA Astrophysics Data System (ADS)

Turner, Neil Macdonald

The authors of this paper are the three General Lighthouse Authorities (GLAs) of the United Kingdom and the Republic of Ireland. It was presented on their behalf at the RIN-96 conference by Captain Turner. The paper gives a brief overview of the policy of the GLAs (i.e. the Corporation of Trinity House, the Northern Lighthouse Board and the Commissioners of Irish Lights) regarding the provision of an aids to navigation service with emphasis on the future prospects of traditional aids to navigation over the next 25 years. The three GLAs have recently carried out a consultation exercise on marine aids to navigation into the 21st century. The results of this consultation exercise are discussed. It should be noted that, for clarity, the General Lighthouse Authorities (GLAs) refer to the systems that they provide as (AtoN), to differentiate their provision from the equipment carried on board ships for navigational purposes which are referred to by the GLAs as . This paper therefore in the main deals with AtoN.The coastlines within the GLAs' areas of responsibility rank with the most heavily trafficked and dangerous in the world. The coastlines vary from isolated rocks and the steep, Atlantic coastline, to the low-lying relatively featureless coastline of south-east England, off which are shifting sandbanks and channels. The tidal range in GLA waters is significant and tidal streams can reach 10 knots or more in a number of places.

The influence of storm wave climate and sediment availability in the evolution of the southwestern Spanish coast.

NASA Astrophysics Data System (ADS)

Plomaritis, T. A.; Del Río, L.; Benavente, J.; Ribera, P.; Anfuso, G.

2009-04-01

The character and configuration of the coastline can be understood in terms of the dynamic balance existing between the physical forcing and the resistance of the coastline. Hence variations in terrestrial, atmospheric and oceanographic extreme conditions have to be evaluated when assessing shoreline changes that can lead to coastal geo-hazards. In the present work the wave record of the last 44 years was analysed for the Spanish gulf of Cadiz (SW Iberian Peninsula) in order to identify changes in the duration, frequency, chronology and direction of approach of the Atlantic storms. Various wave parameters influencing coastal morphology were analysed including maximum wave height, total energy per storm and storm groupiness. The obtained time-series are compared with the NAO index in order to establish a correlation between large-scale atmospheric phenomena and the wave energy arriving to the Gulf of Cadiz. On the other hand, dam construction data on river basins in the area are used to estimate variations in sediment supply to the coast in the last 70 years. Furthermore, medium-term shoreline changes along the study area, for coastlines with variable river influence, are calculated by means of GIS tools on several sets of aerial photographs spanning the period 1956-2002. Finally, the results about variations in terrestrial and oceanographic parameters are compared with the obtained shoreline changes in order to assess their relative influence on coastline evolution.

Rise of the central Andean coast by earthquakes straddling the Moho

NASA Astrophysics Data System (ADS)

Melnick, Daniel

2016-05-01

Surface movements during the largest subduction zone earthquakes commonly drown coastlines. Yet, on geological timescales, coastlines above subduction zones uplift. Here I use a morphometric analysis combined with a numerical model of landscape evolution to estimate uplift rates along the central Andean rasa--a low-relief coastal surface bounded by a steep cliff formed by wave erosion. I find that the rasa has experienced steady uplift of 0.13 +/- 0.04 mm per year along a stretch of more than 2,000 km in length, during the Quaternary. These long-term uplift rates do not correlate with Global Positioning System (GPS) measurements of interseismic movements over the decadal scale, which implies that permanent uplift is not predominantly accumulated during the interseismic period. Instead, the rate of rasa uplift correlates with slip during earthquakes straddling the crust-mantle transition, the Moho. Such deeper earthquakes with magnitude 7 to 8 that occurred between 1995 and 2012 resulted in decimetres of coastal uplift. Slip during these earthquakes is located below the locked portion of the plate interface, and therefore may translate into permanent deformation of the overlying plate, where it causes uplift of the coastline. Thus, lower parts of the plate boundary are stably segmented over hundreds to millions of years. I suggest the coastline marks the surface expression of the transition between the shallow, locked seismogenic domain and the deeper, conditionally stable domain where modest earthquakes build up topography.

Holocene evolution of Dahab coastline - Gulf of Aqaba, Sinai Peninsula, Egypt

NASA Astrophysics Data System (ADS)

Magdy, Torab

2016-04-01

Dahab was a little Bedouin-village in Sinai Peninsula at the mid-western coast of Gulf of Aqaba approx. 90 km north of Sharm-el-Sheikh City and it means "gold" in Arabic language. But in the past 20 years ago it becomes one of the most tourist sites in Egypt. The basement complex is composed mostly of biotiteaplite-granite, mica-aplitegranite, granodiorite, quartzdiorite, alaskite, and diorite. Based on correlation with similar igneous in the most southern part of Sinai and the Red Sea area. Wadi Dahab composed of igneous and metamorphic rocks and the coastline is formed of the fragments of its rocks, mixed with fragments of coral reef and fluvial deposits of Wadi Dahab. The morphology of Dahab coastline is characterized by hooked marine spit, which composed of fluvial sediments carried by marine current from wadi Dahab mouth, this spit encloses shallow lagoon, but the active deposition on the lagoon bottom will evaluate it into saline marsh. This paper dealing with the evolution of Dahab spit and lagoon during the Holocene in addition to the recent time for last 100 years, and it impacts of the future management of the coast area. The coastline mapping during the period of study depends upon GIS technique for data were collected during field measuring by using total station, aerial photo and satellite image interpretation as well as soil sample dating. Suggested geomorphological evolution of Dahab area during the Holocene depending upon geomorphic investigation of the sedimentological process into 6 stages.

Development of pan-Arctic database for river chemistry

USGS Publications Warehouse

McClelland, J.W.; Holmes, R.M.; Peterson, B.J.; Amon, R.; Brabets, T.; Cooper, L.; Gibson, J.; Gordeev, V.V.; Guay, C.; Milburn, D.; Staples, R.; Raymond, P.A.; Shiklomanov, I.; Striegl, Robert G.; Zhulidov, A.; Gurtovaya, T.; Zimov, S.

2008-01-01

More than 10% of all continental runoff flows into the Arctic Ocean. This runoff is a dominant feature of the Arctic Ocean with respect to water column structure and circulation. Yet understanding of the chemical characteristics of runoff from the pan-Arctic watershed is surprisingly limited. The Pan- Arctic River Transport of Nutrients, Organic Matter, and Suspended Sediments ( PARTNERS) project was initiated in 2002 to help remedy this deficit, and an extraordinary data set has emerged over the past few years as a result of the effort. This data set is publicly available through the Cooperative Arctic Data and Information Service (CADIS) of the Arctic Observing Network (AON). Details about data access are provided below.

Dynamical mechanisms of Arctic amplification.

PubMed

Dethloff, Klaus; Handorf, Dörthe; Jaiser, Ralf; Rinke, Annette; Klinghammer, Pia

2018-05-12

The Arctic has become a hot spot of climate change, but the nonlinear interactions between regional and global scales in the coupled climate system responsible for Arctic amplification are not well understood and insufficiently described in climate models. Here, we compare reanalysis data with model simulations for low and high Arctic sea ice conditions to identify model biases with respect to atmospheric Arctic-mid-latitude linkages. We show that an appropriate description of Arctic sea ice forcing is able to reproduce the observed winter cooling in mid-latitudes as result of improved tropospheric-stratospheric planetary wave propagation triggering a negative phase of the Arctic Oscillation/North Atlantic Oscillation in late winter. © 2018 New York Academy of Sciences.

Reactivity of Pleistocene aged organic matter in the Siberian Arctic

NASA Astrophysics Data System (ADS)

Davydov, S.; Vonk, J. E.; Mann, P. J.; Davydova, A.; Sobczak, W. V.; Schade, J. D.; Bulygina, E. B.; Zimov, S. A.; Holmes, R. M.

2011-12-01

Half of the global stock of soil organic carbon (OC) is stored in Arctic permafrost. About one third of this pool consists of so-called yedoma, organic-rich deposits that were formed during the Pleistocene. Previous studies show rapid respiration of yedoma upon thawing, with the potential release of large quantities of relict OC into the contemporary C cycle. The fluvial and coastal reactivity of this OC, however, and its fate remain unclear. Duvannyi Yar is a well-studied yedoma exposure on the banks of Kolyma River in Northeastern Siberia. It can serve as a model for the >7000 km long East Siberian Arctic coastline that is dominated by similarly exposed yedoma cliffs, and is increasingly vulnerable to erosion with climate warming-induced decreases in sea-ice, and increases in storms and wave-fetch. Permafrost thaw causes the slopes of Duvannyi Yar to retreat 3-5 m/y, producing mudstreams that drain into the Kolyma River. These streams are heavily loaded with freshly thawed yedoma sediments (ca. 650 g/L; POC ca. 10 g/L; DOC ca. 150 mg/L). Partial CO2 pressure in these streams was on average 8400 ppm (stdev 2100; n=4) whereas the Kolyma River at the stream mouth contained CO2 concentrations of ca. 900 ppm (stdev 90; n=4), suggesting substantial outgassing during transport. We performed biological oxygen demand assays in combination with a set of incubations to estimate OC lability in a range of dilutions of Duvannyi Yar water with Kolyma River and East Siberian Sea water, in combination with nutrient and enzymatic activity rate analysis to identify potential limitation processes. Our goal was to assess carbon consumption rates and the effect of different microbial communities along its transport towards the ocean. O2 loss (% after 24h) increased significantly from undiluted Kolyma water to increasingly spiked dilutions with filtered Duvannyi Yar filtered water; 0%/0.5%/1%/10%/100% dilutions showed O2 losses of 1.6%, 3.5%, 5.1%, 13% and 35%, respectively. However, C-normalized O2 losses demonstrated a different pattern. After a 24h C-loss of 5-7% for all three dilutions, the 10% dilution continued to respond up to a total of 33% lost carbon after 5 days. Enzymatic activity rates of the lignin-degrading enzyme phenoloxidase corroborated this by showing strongly elevated activity rates for the 10% Duvannyi Yar-Kolyma dilution, opposite to the 1% or 0.5% dilutions or Kolyma background. Dilutions with Kolyma water showed a slightly but consistently higher processing rate compared to dilutions of East Siberian Sea water (26 salinity). These results suggest that old OC is biologically labile upon fluvial release and its breakdown appears to be limited by availability of organic substrates. Furthermore, it appears that refractory carbon in the Kolyma is in fact being processed faster when enough Duvannyi Yar water, along with its microbes and enzymes, is added.

Freshwater Export from the Arctic Ocean and its Downstream Effect on Labrador Sea Deep Convection in a High-Resolution Numerical Model

DTIC Science & Technology

2010-12-01

Arctic has been observed in the northern Canadian Arctic Archipelago ( Bourke and McLaren 1992). There, thick multiyear ice of Arctic origin encounters...Affairs, 87(2), 63-77. 172 Bourke , R. H., and A. S. McLaren, 1992: Contour mapping of Arctic Basin ice draft and roughness parameters. J. Geophys

Application of Network Analysis to Identify and Map Relationships between Information Systems in the context of Arctic Sustainability

NASA Astrophysics Data System (ADS)

Kontar, Y. Y.

2017-12-01

The Arctic Council is an intergovernmental forum promoting cooperation, coordination and interaction among the Arctic States and indigenous communities on issues of sustainable development and environmental protection in the North. The work of the Council is primarily carried out by six Working Groups: Arctic Contaminants Action Program, Arctic Monitoring and Assessment Programme, Conservation of Arctic Flora and Fauna, Emergency Prevention, Preparedness and Response, Protection of the Arctic Marine Environment, and Sustainable Development Working Group. The Working Groups are composed of researchers and representatives from government agencies. Each Working Group issues numerous scientific assessments and reports on a broad field of subjects, from climate change to emergency response in the Arctic. A key goal of these publications is to contribute to policy-making in the Arctic. Complex networks of information systems and the connections between the diverse elements within the systems have been identified via network analysis. This allowed to distinguish data sources that were used in the composition of the primary publications of the Working Groups. Next step is to implement network analysis to identify and map the relationships between the Working Groups and policy makers in the Arctic.

4D Arctic: A Glimpse into the Structure and Evolution of the Arctic in the Light of New Geophysical Maps, Plate Tectonics and Tomographic Models.

PubMed

Gaina, Carmen; Medvedev, Sergei; Torsvik, Trond H; Koulakov, Ivan; Werner, Stephanie C

Knowledge about the Arctic tectonic structure has changed in the last decade as a large number of new datasets have been collected and systematized. Here, we review the most updated, publicly available Circum-Arctic digital compilations of magnetic and gravity data together with new models of the Arctic's crust. Available tomographic models have also been scrutinized and evaluated for their potential to reveal the deeper structure of the Arctic region. Although the age and opening mechanisms of the Amerasia Basin are still difficult to establish in detail, interpreted subducted slabs that reside in the High Arctic's lower mantle point to one or two episodes of subduction that consumed crust of possibly Late Cretaceous-Jurassic age. The origin of major igneous activity during the Cretaceous in the central Arctic (the Alpha-Mendeleev Ridge) and in the proximity of rifted margins (the so-called High Arctic Large Igneous Province-HALIP) is still debated. Models of global plate circuits and the connection with the deep mantle are used here to re-evaluate a possible link between Arctic volcanism and mantle plumes.

Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980

NASA Astrophysics Data System (ADS)

Breider, Thomas J.; Mickley, Loretta J.; Jacob, Daniel J.; Ge, Cui; Wang, Jun; Payer Sulprizio, Melissa; Croft, Betty; Ridley, David A.; McConnell, Joseph R.; Sharma, Sangeeta; Husain, Liaquat; Dutkiewicz, Vincent A.; Eleftheriadis, Konstantinos; Skov, Henrik; Hopke, Phillip K.

2017-03-01

Arctic observations show large decreases in the concentrations of sulfate and black carbon (BC) aerosols since the early 1980s. These near-term climate-forcing pollutants perturb the radiative balance of the atmosphere and may have played an important role in recent Arctic warming. We use the GEOS-Chem global chemical transport model to construct a 3-D representation of Arctic aerosols that is generally consistent with observations and their trends from 1980 to 2010. Observations at Arctic surface sites show significant decreases in sulfate and BC mass concentrations of 2-3% per year. We find that anthropogenic aerosols yield a negative forcing over the Arctic, with an average 2005-2010 Arctic shortwave radiative forcing (RF) of -0.19 ± 0.05 W m-2 at the top of atmosphere (TOA). Anthropogenic sulfate in our study yields more strongly negative forcings over the Arctic troposphere in spring (-1.17 ± 0.10 W m-2) than previously reported. From 1980 to 2010, TOA negative RF by Arctic aerosol declined, from -0.67 ± 0.06 W m-2 to -0.19 ± 0.05 W m-2, yielding a net TOA RF of +0.48 ± 0.06 W m-2. The net positive RF is due almost entirely to decreases in anthropogenic sulfate loading over the Arctic. We estimate that 1980-2010 trends in aerosol-radiation interactions over the Arctic and Northern Hemisphere midlatitudes have contributed a net warming at the Arctic surface of +0.27 ± 0.04 K, roughly one quarter of the observed warming. Our study does not consider BC emissions from gas flaring nor the regional climate response to aerosol-cloud interactions or BC deposition on snow.

Erosion of water-based cements evaluated by volumetric and gravimetric methods.

PubMed

Nomoto, Rie; Uchida, Keiko; Momoi, Yasuko; McCabe, John F

2003-05-01

To compare the erosion of glass ionomer, zinc phosphate and polycarboxylate cements using volumetric and gravimetric methods. For the volumetric method, the eroded depth of cement placed in a cylindrical cavity in PMMA was measured using a dial gauge after immersion in an eroding solution. For the gravimetric method, the weight of the residue of a solution in which a cylindrical specimen had been immersed was measured. 0.02 M lactic acid solution (0.02 M acid) and 0.1 M lactic acid/sodium lactate buffer solution (0.1 M buffer) were used as eroding solutions. The pH of both solutions was 2.74 and the test period was 24 h. Ranking of eroded depth and weight of residue was polycarboxylate>zinc phosphate>glass ionomers. Differences in erosion were more clearly defined by differences in eroded depth than differences in weight of residue. In 0.02 M acid, the erosion of glass ionomer using the volumetric method was effected by the hygroscopic expansion. In 0.1 M buffer, the erosion for polycarboxylate and zinc phosphate using the volumetric method was much greater than that using the gravimetric method. This is explained by cryo-SEM images which show many holes in the surface of specimens after erosion. It appears that zinc oxide is dissolved leaving a spongy matrix which easily collapses under the force applied to the dial gauge during measurement. The volumetric method that employs eroded depth of cement using a 0.1 M buffer solution is able to quantify erosion and to make material comparisons.

SEARCH: Study of Environmental Arctic Change—A System-scale, Cross-disciplinary Arctic Research Program

NASA Astrophysics Data System (ADS)

Wiggins, H. V.; Eicken, H.; Fox, S. E.

2012-12-01

SEARCH is an interdisciplinary and interagency program that works with academic and government agency scientists to plan, conduct, and synthesize studies of arctic change. The vision of SEARCH is to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. Towards this end, SEARCH: 1. Generates and synthesizes research findings and promotes arctic science and scientific discovery across disciplines and among agencies. 2. Identifies emerging issues in arctic environmental change. 3. Provides information resources to arctic stakeholders, policy-makers, and the public to help them respond to arctic environmental change. 4. Coordinates with national arctic science programs integral to SEARCH goals. 5. Facilitates research activities across local-to-global scales with stakeholder concerns incorporated from the start of the planning process. 6. Represents the U.S. arctic environmental change science community in international and global change research initiatives. Specific current activities include: Arctic Observing Network (AON) - coordinating a system of atmospheric, land- and ocean-based environmental monitoring capabilities that will significantly advance our observations of arctic environmental conditions. Arctic Sea Ice Outlook ¬- an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. In April, the SEARCH Science Steering Committee (SSC) released a set of draft 5-year goals and objectives for review by the broader arctic science community. The goals and objectives will direct the SEARCH program in the next five years. The draft SEARCH goals focus on four areas: ice-diminished Arctic Ocean, warming permafrost, land ice and sea level, and societal and policy implications. Together, the goals will provide significant insight into arctic system change as a whole. The SEARCH SSC will release the goals in their revised form and then work closely with agency representatives to implement the goals through research opportunities and community activities. SEARCH is guided by a Science Steering Committee and several panels and working groups, with broad representation of the research community. SEARCH is sponsored by eight U.S. agencies, including: the National Science Foundation (NSF), the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA), the Department of Defense (DOD), the Department of Energy (DOE), the Department of the Interior (DOI), the Smithsonian Institution, and the U.S. Department of Agriculture (USDA). The U.S. Arctic Research Commission participates as an agency observer. For further information, please visit the website: http://www.arcus.org/search or contact: Helen V. Wiggins: helen@arcus.org, SEARCH Project Office, Arctic Research Consortium of the U.S. (ARCUS).

Storm surges formation in the White and Barents Seas

NASA Astrophysics Data System (ADS)

Arkhipkin, Victor; Dobrolyubov, Sergey; Korablina, Anastasia; Myslenkov, Stanislav

2016-04-01

Investigation of storm surges in the Arctic seas are of high priority in Russia due to the active development of offshore oil and gas, construction of facilities in the coastal zone, as well as for the safety of navigation. It is important to study the variability of surges, to predict this phenomena and subsequent economic losses, thus including such information into the Russian Arctic Development Program 2020. Surges in the White and Barents Seas are caused mainly by deep cyclones of two types: "diving" from the north (88% of all cyclones) and western. The average height of the storm surges in the White Sea is 0.6-0.9 m. An average duration of storm surges is about 80 hours. Mathematical modeling is used to analyze the characteristics of storm surges formation in the Dvina Bay of the White Sea, and in the Varandey village on the Barents Sea coast. Calculating storm surge heights in the White and Barents seas is performed using the ADCIRC model on an unstructured grid with a step from 20 km in the Barents Sea to 100 m in the White Sea. Unstructured grids allowed keeping small features of the coastline of the White and Barents seas, small islands and shallow banks, and assessing their impact on the development and transformation of wind-generated waves. The ADCIRC model used data of wind field reanalysis CFSv2. The storm surges were simulated for the time period from 1979 to 2010 and included scenarios with / without direct atmospheric pressure forcing, waves and tides. Numerical experiments have revealed distribution of storm surges in channels of the Northern Dvina River delta. The storm surges spreads in the model from the north-north-west of the Dvina Bay. As storm surge moves from the wellhead to the seaside estuary of the Northern Dvina (district Solombala), its height increases from 0.5 to 2 m. We also found a non-linear interaction of the surge and tide during the phase of surge destruction. This phenomenon is the highest in the period of low water, and the smallest in the period full of water. Analysis of storm surges in the Varandey village (the southern part of the Barents Sea) showed that the maximum height of storm surge reached 2.9 m in this region in July, 2010. The work performed was supported by the RSCF (grant № 14-37-00038)

Reorganization of Ice Sheet Flow Patterns in Arctic Canada Prior to the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Refsnider, K. A.; Miller, G. H.

2010-12-01

The Foxe sector of the Laurentide Ice Sheet (LIS) experienced a complex and dynamic interplay between cold-based, non-erosive ice on uplands, fast-moving outlet glaciers that carved deep fiords through the Arctic Cordillera, and even more erosive ice streams that occupied larger straits and sounds, transporting ice from the Foxe Dome to calving margins in Baffin Bay and the Labrador Sea. The high topography of Baffin Island forms a broad barrier to the flow of ice to these calving margins and gradually has been dissected since the onset of Northern Hemisphere glaciation. However, evidence for the evolution of LIS erosion and basal thermal regime patterns during successive glaciations is poorly preserved in the geologic record. We use a new approach utilizing published till geochemistry and cosmogenic radionuclide (CRN) data to constrain the development of the fiorded coastline and the distribution of cold-based ice across central Baffin Island in both spatial and temporal domains over many glacial-interglacial cycles. The combination of till geochemistry data, which is used to characterize till weathering, and modeled CRN burial-exposure histories provides strong evidence for a shift in basal thermal regimes across the interior plateaux of Baffin Island between 1.9 and 1.2 Ma. While it may be coincidence that this time interval abuts the onset of the mid-Pleistocene transition (MPT), it has been hypothesized that changes in subglacial conditions were potentially an important mechanism in altering LIS dynamics across the MPT. Prior to this time, ice was likely wet-based and erosive across the majority of the Baffin Island interior, but by 1.9-1.2 Ma, some parts of the landscape became perpetually covered by cold-based ice during glaciations, a pattern that persisted through the last glacial cycle. The modern fiord system also must have developed by this time, and preferential channeling of ice flow into major fiords may have been sufficient to effectively shut off ice flow across the landscape between outlet glaciers. These results imply that there was a major shift in the basal thermal regime across the northeastern LIS, and the subsequent expansion of cold-based ice and the concentration of ice flow in fewer outlet systems across this region may help explain the cause of the MPT from 41- to 100-kyr glacial cycles.

BAID: The Barrow Area Information Database - An Interactive Web Mapping Portal and Cyberinfrastructure Showcasing Scientific Activities in the Vicinity of Barrow, Arctic Alaska.

NASA Astrophysics Data System (ADS)

Escarzaga, S. M.; Cody, R. P.; Kassin, A.; Barba, M.; Gaylord, A. G.; Manley, W. F.; Mazza Ramsay, F. D.; Vargas, S. A., Jr.; Tarin, G.; Laney, C. M.; Villarreal, S.; Aiken, Q.; Collins, J. A.; Green, E.; Nelson, L.; Tweedie, C. E.

2015-12-01

The Barrow area of northern Alaska is one of the most intensely researched locations in the Arctic and the Barrow Area Information Database (BAID, www.barrowmapped.org) tracks and facilitates a gamut of research, management, and educational activities in the area. BAID is a cyberinfrastructure (CI) that details much of the historic and extant research undertaken within in the Barrow region in a suite of interactive web-based mapping and information portals (geobrowsers). The BAID user community and target audience for BAID is diverse and includes research scientists, science logisticians, land managers, educators, students, and the general public. BAID contains information on more than 12,000 Barrow area research sites that extend back to the 1940's and more than 640 remote sensing images and geospatial datasets. In a web-based setting, users can zoom, pan, query, measure distance, save or print maps and query results, and filter or view information by space, time, and/or other tags. Additionally, data are described with metadata that meet Federal Geographic Data Committee standards. Recent advances include the addition of more than 2000 new research sites, the addition of a query builder user interface allowing rich and complex queries, and provision of differential global position system (dGPS) and high-resolution aerial imagery support to visiting scientists. Recent field surveys include over 80 miles of coastline to document rates of erosion and the collection of high-resolution sonar data for bathymetric mapping of Elson Lagoon and near shore region of the Chukchi Sea. A network of five climate stations has been deployed across the peninsula to serve as a wireless net for the research community and to deliver near real time climatic data to the user community. Local GIS personal have also been trained to better make use of scientific data for local decision making. Links to Barrow area datasets are housed at national data archives and substantial upgrades have been made to the BAID website and web mapping applications to include the public release of a new multi-temporal Imagery Viewer that allow users to interact with and compare imagery of the Barrow area from 1949 to present.

The North Slope of Alaska and Tourism: Potential Impacts on the Arctic National Wildlife Refuge (ANWR)

NASA Astrophysics Data System (ADS)

Everett, L. R.

2004-12-01

The hydrocarbon industry of Alaska is currently the leading producer of revenue for the Alaskan state economy. Second only to hydrocarbons is the tourism industry. Tourism has been a viable industry since the 1890's when cruises touted the beauty of glaciers and icebergs along the Alaskan coastline. This industry has seen a steady growth for the past few decades throughout the state. The North Slope of Alaska, particularly Prudhoe Bay and the National Petroleum Reserve, has long been associated with hydrocarbon development and today displays a landscape dotted with gravel drill pads, gas and oil pipelines and housing for the oil workers. While tourism is not usually considered hand in hand with the hydrocarbon industry, it has mimicked the development of hydrocarbons almost since the beginning. Today one not only sees the effects of the oil industry on the North Slope, but also the tourist industry as planes unload dozens of tourists, or tour buses and private vehicles arrive daily via the Dalton Highway. In Deadhorse, hotels that once only housed the oil workers now welcome the tourist, offering tours of the oil fields and adjacent areas and have become jumping off sites for wilderness trips. Tourism will create jobs as well as revenue. However, at present, there are few restrictions or guidelines in place that will deal with the potential impacts of increased tourism. Because of this there are many concerns about the possible impacts tourism and the infrastructure development will have on the North Slope. To list several concerns: (1) What are the impacts of increased tourism and the infrastructure development? (2) What will the impacts be on the Arctic National Wildlife Refuge (ANWR), which sits a mere 60 miles to the east of Deadhorse? (3) Will hydrocarbon development in ANWR and the associated infrastructure exacerbate potential impact by encouraging greater use of the Refuge by tourists? (4) Will tourism itself have a negative impact on this fragile environment? Safeguarding the fragile environment of ANWR and for that matter all of the North Slope for future generations will require that all types of environmental impacts are carefully considered. The majority of this region is underlain by permafrost and is at risk because of possible global warming coupled with infrastructure development, tourism and potential hydrocarbon development.

Late-Quaternary glaciation and postglacial emergence, southern Eureka Sound, high-Arctic Canada

NASA Astrophysics Data System (ADS)

O Cofaigh, Colm Seamus

Eureka Sound is the inter-island channel separating Ellesmere and Axel Heiberg islands, High Arctic Canada. This thesis reconstructs the glacial and sea level history of southern Eureka Sound through surficial geological mapping, studies of glacial sedimentology and geomorphology, surveying of raised marine shorelines, radiocarbon dating of marine shells and driftwood and surface exposure dating of erratics and bedrock. Granite dispersal trains, shelly till and ice-moulded bedrock record westerly-flow of warm-based, regional ice into Eureka Sound from a source on southeastern Ellesmere Island during the late Wisconsinan. Regional ice was coalescent with local ice domes over Raanes and northern Svendsen peninsulas. Marine limit (dating <=9.2 ka BP; <=9.9 ka cal BP) is inset into the dispersal trains and records early Holocene deglaciation of regional ice. Collectively these data indicate an extensive ice-cover in southern Eureka Sound during the Last Glacial Maximum. Ice-divides were located along the highlands of central Ellesmere and Axel Heiberg islands, from which ice converged on Eureka Sound, and subsequently flowed north and south along the channel. Deglaciation was characterised by a two-step retreat pattern, likely triggered by eustatic sea level rise and abrupt early Holocene warming. Initial break-up and radial retreat of ice in Eureka Sound and the larger fiords, preceded terrestrial stabilisation along coastlines and inner fiords. Location of deglacial depocentres was predominantly controlled by fiord bathymetry. Regionally, two-step deglaciation is reflected by prominent contrasts in glacial geomorphology between the inner and outer parts of many fiords. Glacial sedimentological and geomorphological evidence indicates spatial variation in basal thermal regime between retreating trunk glaciers. Holocene emergence of up to 150 m asl along southern Eureka Sound is recorded by raised marine deltas, beaches and washing limits. Emergence curves exhibit marked contrasts in the form and rate of initial unloading. Isobases drawn on the 8.5 ka shoreline for greater Eureka Sound demonstrate that a cell of highest emergence extends along the length of the channel, and closes in the vicinity of the entrance to Norwegian Bay. The isobase pattern indicates a distinct loading centre over the sound, and in conjunction with glacial geological evidence, suggests that the thickest late Wisconsinan ice lay over the channel.

Reshaping of Coastlines as the Beginning of Urban Structures Changes in North Poland

NASA Astrophysics Data System (ADS)

Burda, Izabela M.; Nyka, Lucyna; Borodziuk, Adam

2017-10-01

This article discusses the problem of strategies concerning the processes of re-shaping the Baltic Sea southern coastline applied recently in North Poland. The undertaken research is an attempt to identify the relationship between the modifications of coastline forms and the positive changes of urban structures. First of all, it can be seen that these modifications are needed because of the problems of existing shoreline erosion. It can be also observed, that many realized interventions were helpful to save the land but they did not improve the condition of cities situated along the coast. In these cases, it is impossible to connect the sea coastline with the existing grid of public spaces which is a barrier to creating a system that could be perceived as a coherent landscape. The basis for proving the importance of special ways of shoreline modifications are comparative studies and in-field analyses. In facing the problems of coastal cities there is a need to analyse the condition of existing urban structures. Many studies made so far show that there are many problems which have to be identified and solved. Worth noting is the fact that these structures have a unique character because of their location. They play an important role as holiday resorts being an attraction for many inhabitants and visitors from all over the world. Such a role plays, for example, an important part in places such as Jarosławiec, Ustka or Kołobrzeg. However, analysing the strategies applied in recent years, it can be noted that they cannot be the only basis for the strengthening of connections between land and water helping to preserve the land, but they may also play an important role as a factor for initiating urban structures transformations. What is also important, it can be claimed that relationships between sea water and urban structures should be strengthened due to special forms of the coast line. They should be integrated into existing structures making them more comfortable and attractive while also protecting against threats from the water. Playing the role as a protector of land they should use special constructions being at the same time accessible to all users throughout the year and regardless of weather conditions. It is worth emphasizing that special treatment of the coastline helps to establish it as a public domain which is important in achieving high quality urban-water landscapes. Therefore it should be the objective of strategies which are being prepared for parts of coastlines waiting for intervention.

Modelling changes in the coastal geomorphology of Unst, Shetland and the implications for understanding High to Late Medieval harbour changes in the Norse North Atlantic

NASA Astrophysics Data System (ADS)

Preston, John; Dugmore, Andrew; Newton, Anthony; Mudd, Simon

2016-04-01

The Norse settlement of the North Atlantic islands relied upon a network of harbours that also played a key role in the development of North European economies through the late Middle Ages. However, many of these harbours fell into disuse, their locations are uncertain and the reasons for this are unclear. A crucial geomorphological characteristic of a successful harbour is structural equilibrium. A harbour must have physical stability (or a dynamic equilibrium in the case of a beach) for boats to use it safely season to season, year on year. In the absence of a major civil engineering effort, something that was not possible in the pre-modern Atlantic islands, the geomorphology of a harbour is a key indicator of its physical equilibrium (or otherwise). Should the harbour be located on a changeable coastline (or one that becomes changeable) it may become unviable. Conversely, a harbour may be located on a coastline stable over centennial timescales, where little geomorphological change occurs, infrastructure can endure and many aspects of the physical environment remain predictable. The geomorphological setting of Norse harbours in the Atlantic is variable, with contrasting landform stability over short, medium and long time scales. We assess geomorphological change on the island of Unst, the most northerly of the British Isles, a coastline used by the Norse as well as earlier and later societies. This island offers a complex coastline of deep fjords and arcuate embayments and thus significant differences in forces acting upon the coastline. There is also evidence for instability in the beaches used by the Norse that could have been driven by the changes in climate conditions from the Medieval Climatic Anomaly to the Little Age and the present day. We model coastlines using the sediment dynamics model MIKE21. Model results agree well with the location of extant sandy beaches on Unst, but model runs with modern environmental drivers also build sandy beaches where none currently exist. Blown sand deposits were formed in the 12th-13th century, consistent with High Medieval settlement times and the onset of the Little Ice Age, suggesting that some of the Norse landing sites began to destabilise at this time. This research shows how beach instability can be modelled to determine the likely circumstances under which beaches formed, changed or disappeared and thus the potential geomorphological drivers of coastal change, harbour use and our ability to identify past harbour sites.

Potential fate of eroded SOC after erosion

NASA Astrophysics Data System (ADS)

Xiao, Liangang; Fister, Wolfgang; Greenwood, Philip; Hu, Yaxian; Kuhn, Nikolaus J.

2015-04-01

Globally, soils contain more than three times as much carbon as either atmosphere or terrestrial vegetation. Soil erosion moves soil organic carbon (SOC) from the site of soil and SOC formation and to depositional environments. There some SOC might be sequestered. Combined with dynamic replacement at the site of erosion, the effect can significantly influence the carbon cycle. However, the fate of SOC moved by erosion has been subject to an intense controversy. Two opposing views prevail: erosion may contribute to SOC mineralization during transport and thus act as a source for atmospheric CO2; the burial of SOC, on the other hand, can be seen as a sink while dynamic replacement maintains SOC at the eroding site and thus increase the C-stocks in soils and sediments. The debate suffers from a lack of information on the distribution, movement and fate of SOC in terrestrial ecosystems. This study aims to improve our understanding of the transport and subsequent fate of the eroded soil and the associated SOC. The research presented here focused on the SOC content and potential transport distance of erode soil. During a series of simulated rainfall soil eroded on crusted loess soils near Basel, Switzerland, was collected. The sediment was fractionated according to its settling velocity, with classes set to correspond to either a transfer into rivers or a deposition on slopes. The soil mass, SOC concentration and cumulative CO2 emission of each fraction were measured. Our results show that about 50% of the eroded sediment and 60% of the eroded SOC are likely to be deposited on the slopes, even during a high rainfall intensity event. This is 3 times greater than the association of SOC with mineral particles suggests. The CO2 emission of the eroded soil is increased by 40% compared to disturbed bulk soil. This confirms that aggregate breakdown reduces the protection of SOC in aggregates. Both results of this study show that taking (i) the effect of aggregation on SOC redistribution and (ii) the subsequent CO2 emission during the transport have to be considered to achieve a reliable assessment of the effect of soil erosion on the global C-cycle. They also indicate that our current balances may underestimate the CO2 emission caused by soil erosion.

Fast evolving conduits in clay-bonded sandstone: Characterization, erosion processes and significance for the origin of sandstone landforms

NASA Astrophysics Data System (ADS)

Bruthans, Jiri; Svetlik, Daniel; Soukup, Jan; Schweigstillova, Jana; Valek, Jan; Sedlackova, Marketa; Mayo, Alan L.

2012-12-01

In Strelec Quarry, the Czech Republic, an underground conduit network > 300 m long with a volume of ~ 104 m3 and a catchment of 7 km2 developed over 5 years by groundwater flow in Cretaceous marine quartz sandstone. Similar landforms at natural exposures (conduits, slot canyons, undercuts) are stabilized by case hardening and have stopped evolving. The quarry offers a unique opportunity to study conduit evolution in sandstone at local to regional scales, from the initial stage to maturity, and to characterize the erosion processes which may form natural landforms prior to stabilization. A new technique was developed to distinguish erodible and non-erodible sandstone surfaces. Based on measurements of relative erodibility, drilling resistance, ambient and water-saturated tensile strength (TS) at natural and quarry exposures three distinct kinds of surfaces were found. 1) Erodible sandstone exposed at ~ 60% of surfaces in quarry. This sandstone loses as much as 99% of TS when saturated. 2) Sub-vertical fracture surfaces that are non-erodible already prior to exposure at ground surface and which keep considerable TS if saturated. 3) Case hardened surfaces that start to form after exposure. In favorable conditions they became non-erodible and reach the full TS in just 6 years. An increase in the hydraulic gradient from ~ 0.005 to > 0.02 triggered conduit evolution, based on long-term monitoring of water table in 18 wells and inflows to the quarry. Rapidly evolving major conduits are characterized by a channel gradient of ~ 0.01, a flow velocity ~ 40 cm/s and sediment concentration ~ 10 g/l. Flow in openings with a discharge 1 ml/s and hydraulic gradient > 0.05 exceeds the erosion threshold and initiates piping. In the first phase of conduit evolution, fast concentrated flow mobilizes erodible sandstone between sets of parallel fractures in the shallow phreatic zone. In the second phase the conduit opening mainly expands vertically upward into the vadose zone by mass wasting of undercut sandstone slabs. Mass wasting is responsible for > 90% of mobilized sandstone. Sides of the mature conduits are protected by non-erodible fracture surfaces. Natural landforms were probably formed very rapidly by overland flow, piping and possibly fluidization during or at the end of the glacial periods when sandstone was not yet protected by case hardening.

Impact of future Arctic shipping on high-latitude black carbon deposition (Invited)

NASA Astrophysics Data System (ADS)

Corbett, J. J.; Browse, J.; Carslaw, K. S.; Schmidt, A.

2013-12-01

The retreat of Arctic sea-ice has led to renewed calls to exploit Arctic shipping routes. The diversion of ship traffic through the Arctic will shorten shipping routes and possibly reduce global shipping emissions. However, deposition of black carbon (BC) aerosol emitted by additional Arctic ships could cause a reduction in the albedo of snow and ice, accelerating snow-melt and sea-ice loss. We use recently compiled Arctic shipping emission inventories for 2004 and 2050 together with a global aerosol microphysics model GLOMAP coupled to the chemical transport model TOMCAT to quantify the contribution of future Arctic shipping to high-latitude BC deposition. Emission rates of SOx (SO2 and SO4) and particulate matter (PM) were estimated for 2050 under both business-as-usual and high-growth scenarios. BC particles are assumed to be water-insoluble at emission but can become active in cloud drop formation through soluble material accumulation. After BC particles become cloud-active they are more efficiently wet scavenged, which accounts for 80% of modeled BC deposition. Current-day Arctic shipping contributes 0.3% to the BC mass deposited north of 60N (250 Gg). About 50% of modelled BC deposition is on open ocean, suggesting that current Arctic ship traffic may not significantly contribute to BC deposition on central Arctic sea ice. However, 6 - 8% of deposited BC on the west coast of Greenland originates from local ship traffic. Moreover, in-Arctic shipping contributes some 32% to high-latitude ship-sourced deposition despite accounting for less than 1.0% of global shipping emissions. This suggests that control of in-Arctic shipping BC emissions could yield greater decrease in high-latitude BC deposition than a similar control strategy applied only to the extra-Arctic shipping industry. Arctic shipping in 2050 will contribute less than 1% to the total BC deposition north of 60N due to the much greater relative contribution of BC transported from non-shipping sources at lower-latitudes (with a maximum of about 5%, considering upper bound estimates for transport). In the BAU and HiG scenarios, the total BC deposition averaged north of 60N from Arctic shipping remains small, increasing to only 0.4% and 0.7%, respectively. Several mitigation strategies confirmed that extra-Arctic sources other than shipping contribute significantly more to BC deposition than Arctic shipping, and that regulation solely aimed at the Arctic shipping industry is an insufficient control on high-latitude BC deposition. An exception is the impact of local shipping near the vulnerable Greenland ice-sheet. Over Greenland the deposited BC mass attributable to high-growth shipping emissions in 2050 is significantly higher (10-15%) than over Arctic sea-ice. The increase in local BC deposition over Greenland can be mitigated by a 10% decrease in North American BC emissions, but additional controls over distant stationary sources should be considered alongside international agreements controlling shipping emissions to achieve desired Arctic BC deposition reductions.

Future scientific drilling in the Arctic Ocean: Key objectives, areas, and strategies

NASA Astrophysics Data System (ADS)

Stein, R.; Coakley, B.; Mikkelsen, N.; O'Regan, M.; Ruppel, C.

2012-04-01

In spite of the critical role of the Arctic Ocean in climate evolution, our understanding of the short- and long-term paleoceanographic and paleoclimatic history through late Mesozoic-Cenozoic times, as well as its plate-tectonic evolution, remains behind that from the other world's oceans. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the Arctic Coring Expedition - ACEX (or IODP Expedition 302), the first Mission Specific Platform (MSP) expedition within IODP, a new era in Arctic research began (Backman, Moran, Mayer, McInroy et al., 2006). ACEX proved that, with an intensive ice-management strategy, successful scientific drilling in the permanently ice-covered central Arctic Ocean is possible. ACEX is certainly a milestone in Arctic Ocean research, but - of course - further drilling activities are needed in this poorly studied ocean. Furthermore, despite the success of ACEX fundamental questions related to the long- and short-term climate history of the Arctic Ocean during Mesozoic-Cenozoic times remain unanswered. This is partly due to poor core recovery during ACEX and, especially, because of a major mid-Cenozoic hiatus in this single record. Since ACEX, a series of workshops were held to develop a scientific drilling strategy for investigating the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system: - "Arctic Ocean History: From Speculation to Reality" (Bremerhaven/Germany, November 2008); - "Overcoming barriers to Arctic Ocean scientific drilling: the site survey challenge" (Copenhagen/Denmark, November 2011); - Circum-Arctic shelf/upper continental slope scientific drilling workshop on "Catching Climate Change in Progress" (San Francisco/USA, December 2011); - "Coordinated Scientific Drilling in the Beaufort Sea: Addressing Past, Present and Future Changes in Arctic Terrestrial and Marine Systems" (Kananaskis, Alberta/Canada, February 2012). During these workshops, key areas and key scientific themes as well as drilling and site-survey strategies were discussed. Major scientific themes for future Arctic drilling will include: - The Arctic Ocean during the transition from greenhouse to icehouse conditions and millennial scale climate changes; - Physical and chemical changes of the evolving Polar Ocean and Arctic gateways; - Impact of Pleistocene/Holocene warming and sea-level rise on upper continental slope and shelf gas hydrates and on shelf permafrost; - Land-ocean interactions; - Tectonic evolution and birth of the Arctic Ocean basin: Arctic ridges, sea floor spreading and global lithosphere processes. When thinking about future Arctic drilling, it should be clearly emphasized that for the precise planning of future Arctic Ocean drilling campaigns, including site selection, evaluation of proposed drill sites for safety and environmental protection, etc., comprehensive site survey data are needed first. This means that the development of a detailed site survey strategy is a major challenge for the coming years. Here, an overview of perspectives and plans for future Arctic Ocean drilling will be presented.

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

NASA Astrophysics Data System (ADS)

Tokinaga, Hiroki; Xie, Shang-Ping; Mukougawa, Hitoshi

2017-06-01

With amplified warming and record sea ice loss, the Arctic is the canary of global warming. The historical Arctic warming is poorly understood, limiting our confidence in model projections. Specifically, Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing. Here, we show that the concurrent phase shift of Pacific and Atlantic interdecadal variability modes is the major driver for the rapid early 20th-century Arctic warming. Atmospheric model simulations successfully reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early 20th-century Arctic warming is associated with positive SST anomalies over the tropical and North Atlantic and a Pacific SST pattern reminiscent of the positive phase of the Pacific decadal oscillation. Atmospheric circulation changes are important for the early 20th-century Arctic warming. The equatorial Pacific warming deepens the Aleutian low, advecting warm air into the North American Arctic. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. Coupled ocean-atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, negative-to-positive phase shift of the Pacific and Atlantic interdecadal modes. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region.

Challenges of climate change: an Arctic perspective.

PubMed

Corell, Robert W

2006-06-01

Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.

Spatio-temporal Analysis of the Genetic Diversity of Arctic Rabies Viruses and Their Reservoir Hosts in Greenland

PubMed Central

Hanke, Dennis; Freuling, Conrad M.; Fischer, Susanne; Hueffer, Karsten; Hundertmark, Kris; Nadin-Davis, Susan; Marston, Denise; Fooks, Anthony R.; Bøtner, Anette; Mettenleiter, Thomas C.; Beer, Martin; Rasmussen, Thomas B.; Müller, Thomas F.; Höper, Dirk

2016-01-01

There has been limited knowledge on spatio-temporal epidemiology of zoonotic arctic fox rabies among countries bordering the Arctic, in particular Greenland. Previous molecular epidemiological studies have suggested the occurrence of one particular arctic rabies virus (RABV) lineage (arctic-3), but have been limited by a low number of available samples preventing in-depth high resolution phylogenetic analysis of RABVs at that time. However, an improved knowledge of the evolution, at a molecular level, of the circulating RABVs and a better understanding of the historical perspective of the disease in Greenland is necessary for better direct control measures on the island. These issues have been addressed by investigating the spatio-temporal genetic diversity of arctic RABVs and their reservoir host, the arctic fox, in Greenland using both full and partial genome sequences. Using a unique set of 79 arctic RABV full genome sequences from Greenland, Canada, USA (Alaska) and Russia obtained between 1977 and 2014, a description of the historic context in relation to the genetic diversity of currently circulating RABV in Greenland and neighboring Canadian Northern territories has been provided. The phylogenetic analysis confirmed delineation into four major arctic RABV lineages (arctic 1–4) with viruses from Greenland exclusively grouping into the circumpolar arctic-3 lineage. High resolution analysis enabled distinction of seven geographically distinct subclades (3.I – 3.VII) with two subclades containing viruses from both Greenland and Canada. By combining analysis of full length RABV genome sequences and host derived sequences encoding mitochondrial proteins obtained simultaneously from brain tissues of 49 arctic foxes, the interaction of viruses and their hosts was explored in detail. Such an approach can serve as a blueprint for analysis of infectious disease dynamics and virus-host interdependencies. The results showed a fine-scale spatial population structure in Greenland arctic foxes based on mitochondrial sequences, but provided no evidence for independent isolated evolutionary development of RABV in different arctic fox lineages. These data are invaluable to support future initiatives for arctic fox rabies control and elimination in Greenland. PMID:27459154

Spatio-temporal Analysis of the Genetic Diversity of Arctic Rabies Viruses and Their Reservoir Hosts in Greenland.

PubMed

Hanke, Dennis; Freuling, Conrad M; Fischer, Susanne; Hueffer, Karsten; Hundertmark, Kris; Nadin-Davis, Susan; Marston, Denise; Fooks, Anthony R; Bøtner, Anette; Mettenleiter, Thomas C; Beer, Martin; Rasmussen, Thomas B; Müller, Thomas F; Höper, Dirk

2016-07-01

There has been limited knowledge on spatio-temporal epidemiology of zoonotic arctic fox rabies among countries bordering the Arctic, in particular Greenland. Previous molecular epidemiological studies have suggested the occurrence of one particular arctic rabies virus (RABV) lineage (arctic-3), but have been limited by a low number of available samples preventing in-depth high resolution phylogenetic analysis of RABVs at that time. However, an improved knowledge of the evolution, at a molecular level, of the circulating RABVs and a better understanding of the historical perspective of the disease in Greenland is necessary for better direct control measures on the island. These issues have been addressed by investigating the spatio-temporal genetic diversity of arctic RABVs and their reservoir host, the arctic fox, in Greenland using both full and partial genome sequences. Using a unique set of 79 arctic RABV full genome sequences from Greenland, Canada, USA (Alaska) and Russia obtained between 1977 and 2014, a description of the historic context in relation to the genetic diversity of currently circulating RABV in Greenland and neighboring Canadian Northern territories has been provided. The phylogenetic analysis confirmed delineation into four major arctic RABV lineages (arctic 1-4) with viruses from Greenland exclusively grouping into the circumpolar arctic-3 lineage. High resolution analysis enabled distinction of seven geographically distinct subclades (3.I - 3.VII) with two subclades containing viruses from both Greenland and Canada. By combining analysis of full length RABV genome sequences and host derived sequences encoding mitochondrial proteins obtained simultaneously from brain tissues of 49 arctic foxes, the interaction of viruses and their hosts was explored in detail. Such an approach can serve as a blueprint for analysis of infectious disease dynamics and virus-host interdependencies. The results showed a fine-scale spatial population structure in Greenland arctic foxes based on mitochondrial sequences, but provided no evidence for independent isolated evolutionary development of RABV in different arctic fox lineages. These data are invaluable to support future initiatives for arctic fox rabies control and elimination in Greenland.

Comparing growth rates of Arctic Cod Boreogadus saida across the Chukchi and Beaufort Seas

NASA Astrophysics Data System (ADS)

Frothingham, A. M.; Norcross, B.

2016-02-01

Dramatic changes to the Arctic have highlighted the need for a greater understanding of the present ecosystem. Arctic Cod, Boreogadus saida, commonly dominate fish assemblages in the Arctic region and inhabit two geographically unique seas in the U.S. Due to the importance of Arctic Cod in the Arctic food web, establishing current benchmark information such as growth rates, will provide a better understanding as to how the species will adapt to the effects of climate change. To investigate differences in Arctic Cod life history across nearly 1500 km of vital habitat, growth rates were examined using a von Bertalanffy growth equation. Arctic Cod were collected from 2009 to 2014 from the Chukchi and Beaufort seas. Arctic Cod collected from the Chukchi Sea had an overall smaller maximum achievable length (210 mm) compared to the Beaufort Sea (253 mm) despite a larger sample size in the Chukchi Sea (n=1569) than the Beaufort Sea (n=1140). Growth rates indicated faster growth in the Chukchi Sea (K =0.33) than in the Beaufort Sea (K= 0.29). Arctic Cod collected from the Chukchi Sea had similar achievable maximum lengths throughout, but those collected from the southern Chukchi Sea grew at faster rates (K=0.45).Arctic Cod in the eastern Beaufort Sea region had a higher overall maximum achievable length (243 mm) than in the western Beaufort Sea region (186 mm). Knowledge about contemporary growth rates of Arctic Cod in the Chukchi and Beaufort Seas can be used in future comparisons to evaluate potential effects of increasing climate change and anthropogenic influences.

Arctic tundra greening and browning (2007-2013) based on satellite-observed solar-induced fluorescence data

NASA Astrophysics Data System (ADS)

Fu, D.; Su, F.; Wang, J.

2017-12-01

More accurate evaluation of the state of Arctic tundra vegetation is important for our understanding of Arctic and global systems. Arctic tundra greening has been reported, increasing vegetation cover and productivity in many regions, but browning has been also reported, based on satellite-observed Normalized Difference Vegetation Index (NDVI) from 2011 until recently. Here we demonstrate a satellite-based method of estimating tundra greenness trend. A more direct indicator of greenness (spatially downscaling solar-induced fluorescence, SIF) was used to analyze the spatial and temporal patterns of Arctic tundra greenness trends based on ordinary least square regression (2007-2013). Meanwhile, two other greenness indices were used for the comparison, which were two NDVI products: GIMMS NDVI3g, and MOD13Q1 Collection 6. Generally, the Arctic tundra was not consistently greening, browning also existed. For the spatial trends, the results showed that most parts of the Arctic tundra below 75ºN was browning (-0.0098 mW/m2/sr/nm/year) using SIF, whereas spatially heterogeneous trends (greening or browning) were obtained based on the two NDVI products. For the temporal trends, the greenness value of Eurasia Arctic tundra is higher than Northern America and the whole Arctic tundra for the three greenness indices. From 2010, the Arctic tundra was greening based on MOD13Q1, whereas is browning using GIMMS NDVI3g. However, the Arctic tundra was obviously browning using SIF data. This study demonstrates a way of investigating the variation of Arctic tundra vegetation via new satellite-observed data.

Variations in freshwater pathways from the Arctic Ocean into the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Wang, Zeliang; Hamilton, James; Su, Jie

2017-06-01

Understanding the mechanisms that drive exchanges between the Arctic Ocean and adjacent oceans is critical to building our knowledge of how the Arctic is reacting to a warming climate, and how potential changes in Arctic Ocean freshwater export may impact the AMOC (Atlantic Meridional Overturning Circulation). Here, freshwater pathways from the Arctic Ocean to the North Atlantic are investigated using a 1 degree global model. An EOF analysis of modeled sea surface height (SSH) demonstrates that while the second mode accounts for only 15% of the variability, the associated geostrophic currents are strongly correlated with freshwater exports through CAA (Canadian Arctic Archipelago; r = 0.75), Nares Strait (r = 0.77) and Fram Strait (r = -0.60). Separation of sea level into contributing parts allows us to show that the EOF1 is primarily a barotropic mode reflecting variability in bottom pressure equivalent sea level, while the EOF2 mode reflects changes in steric height in the Arctic Basin. This second mode is linked to momentum wind driven surface current, and dominates the Arctic Ocean freshwater exports. Both the Arctic Oscillation and Arctic Dipole atmospheric indices are shown to be linked to Arctic Ocean freshwater exports, with the forcing associated with the Arctic Dipole reflecting the out-of-phase relationship between transports through the CAA and those through Fram Strait. Finally, observed freshwater transport variation through the CAA is found to be strongly correlated with tide gauge data from the Beaufort Sea coast (r = 0.81), and with the EOF2 mode of GRACE bottom pressure data (r = 0.85) on inter-annual timescales.

Survival of ship biofouling assemblages during and after voyages to the Canadian Arctic.

PubMed

Chan, Farrah T; MacIsaac, Hugh J; Bailey, Sarah A

2016-01-01

Human-mediated vectors often inadvertently translocate species assemblages to new environments. Examining the dynamics of entrained species assemblages during transport can provide insights into the introduction risk associated with these vectors. Ship biofouling is a major transport vector of nonindigenous species in coastal ecosystems globally, yet its magnitude in the Arctic is poorly understood. To determine whether biofouling organisms on ships can survive passages in Arctic waters, we examined how biofouling assemblage structure changed before, during, and after eight round-trip military voyages from temperate to Arctic ports in Canada. Species richness first decreased (~70% loss) and then recovered (~27% loss compared to the original assemblages), as ships travelled to and from the Arctic, respectively, whereas total abundance typically declined over time (~55% total loss). Biofouling community structure differed significantly before and during Arctic transits as well as between those sampled during and after voyages. Assemblage structure varied across different parts of the hull; however, temporal changes were independent of hull location, suggesting that niche areas did not provide protection for biofouling organisms against adverse conditions in the Arctic. Biofouling algae appear to be more tolerant of transport conditions during Arctic voyages than are mobile, sessile, and sedentary invertebrates. Our results suggest that biofouling assemblages on ships generally have poor survivorship during Arctic voyages. Nonetheless, some potential for transporting nonindigenous species to the Arctic via ship biofouling remains, as at least six taxa new to the Canadian Arctic, including a nonindigenous cirripede, appeared to have survived transits from temperate to Arctic ports.

Arctic marine fishes and their fisheries in light of global change

PubMed Central

Christiansen, Jørgen S; Mecklenburg, Catherine W; Karamushko, Oleg V

2014-01-01

In light of ocean warming and loss of Arctic sea ice, harvested marine fishes of boreal origin (and their fisheries) move poleward into yet unexploited parts of the Arctic seas. Industrial fisheries, already in place on many Arctic shelves, will radically affect the local fish species as they turn up as unprecedented bycatch. Arctic marine fishes are indispensable to ecosystem structuring and functioning, but they are still beyond credible assessment due to lack of basic biological data. The time for conservation actions is now, and precautionary management practices by the Arctic coastal states are needed to mitigate the impact of industrial fisheries in Arctic waters. We outline four possible conservation actions: scientific credibility, ‘green technology’, legitimate management and overarching coordination. PMID:24105993

Effects of Arctic geoengineering on precipitation in the tropical monsoon regions

NASA Astrophysics Data System (ADS)

Nalam, Aditya; Bala, Govindasamy; Modak, Angshuman

2017-07-01

Arctic geoengineering wherein sunlight absorption is reduced only in the Arctic has been suggested as a remedial measure to counteract the on-going rapid climate change in the Arctic. Several modeling studies have shown that Arctic geoengineering can minimize Arctic warming but will shift the Inter-tropical Convergence Zone (ITCZ) southward, unless offset by comparable geoengineering in the Southern Hemisphere. In this study, we investigate and quantify the implications of this ITCZ shift due to Arctic geoengineering for the global monsoon regions using the Community Atmosphere Model version 4 coupled to a slab ocean model. A doubling of CO2 from pre-industrial levels leads to a warming of 6 K in the Arctic region and precipitation in the monsoon regions increases by up to 15%. In our Arctic geoengineering simulation which illustrates a plausible latitudinal distribution of the reduction in sunlight, an addition of sulfate aerosols (11 Mt) in the Arctic stratosphere nearly offsets the Arctic warming due to CO2 doubling but this shifts the ITCZ southward by 1.5° relative to the pre-industrial climate. The combined effect from this shift and the residual CO2-induced climate change in the tropics is a decrease/increase in annual mean precipitation in the Northern Hemisphere/Southern Hemisphere monsoon regions by up to -12/+17%. Polar geoengineering where sulfate aerosols are prescribed in both the Arctic (10 Mt) and Antarctic (8 Mt) nearly offsets the ITCZ shift due to Arctic geoengineering, but there is still a residual precipitation increase (up to 7%) in most monsoon regions associated with the residual CO2 induced warming in the tropics. The ITCZ shift due to our Global geoengineering simulation, where aerosols (20 Mt) are prescribed uniformly around the globe, is much smaller and the precipitation changes in most monsoon regions are within ±2% as the residual CO2-induced warming in the tropics is also much less than in Arctic and Polar geoengineering. Further, global geoengineering nearly offsets the Arctic warming. Based on our results we infer that Arctic geoengineering leads to ITCZ shift and leaves residual CO2 induced warming in the tropics resulting in substantial precipitation decreases (increases) in the Northern (Southern) hemisphere monsoon regions.

SEARCH: Study of Environmental Arctic Change--A System-scale, Cross-disciplinary Arctic Research Program

NASA Astrophysics Data System (ADS)

Shnoro, R. S.; Eicken, H.; Francis, J. A.; Scambos, T. A.; Schuur, E. A.; Straneo, F.; Wiggins, H. V.

2013-12-01

SEARCH is an interdisciplinary, interagency program that works with academic and government agency scientists and stakeholders to plan, conduct, and synthesize studies of Arctic change. Over the past three years, SEARCH has developed a new vision and mission, a set of prioritized cross-disciplinary 5-year goals, an integrated set of activities, and an organizational structure. The vision of SEARCH is to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. SEARCH's 5-year science goals include: 1. Improve understanding, advance prediction, and explore consequences of changing Arctic sea ice. 2. Document and understand how degradation of near-surface permafrost will affect Arctic and global systems. 3. Improve predictions of future land-ice loss and impacts on sea level. 4. Analyze societal and policy implications of Arctic environmental change. Action Teams organized around each of the 5-year goals will serve as standing groups responsible for implementing specific goal activities. Members will be drawn from academia, different agencies and stakeholders, with a range of disciplinary backgrounds and perspectives. 'Arctic Futures 2050' scenarios tasks will describe plausible future states of the arctic system based on recent trajectories and projected changes. These scenarios will combine a range of data including climate model output, paleo-data, results from data synthesis and systems modeling, as well as expert scientific and traditional knowledge. Current activities include: - Arctic Observing Network (AON) - coordinating a system of atmospheric, land- and ocean-based environmental monitoring capabilities that will significantly advance our observations of arctic environmental conditions. - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. A newly-launched Sea Ice Prediction Network will create a network of scientists and stakeholders to generate, assess and communicate Arctic seasonal sea ice forecasts. - Collaboration with the Interagency Arctic Research Policy Committee (IARPC) to implement mutual science goals. SEARCH is sponsored by 8 U.S. agencies, including: the National Science Foundation, the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the Department of Defense, the Department of Energy, the Department of the Interior, the Smithsonian Institution, and the U.S. Department of Agriculture. The U.S. Arctic Research Commission participates as an observer. For more information: http://www.arcus.org/search.

Arctic circulation regimes

PubMed Central

Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L.

2015-01-01

Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

Fresh Water Content Variability in the Arctic Ocean

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Proshutinsky, Andrey

2003-01-01

Arctic Ocean model simulations have revealed that the Arctic Ocean has a basin wide oscillation with cyclonic and anticyclonic circulation anomalies (Arctic Ocean Oscillation; AOO) which has a prominent decadal variability. This study explores how the simulated AOO affects the Arctic Ocean stratification and its relationship to the sea ice cover variations. The simulation uses the Princeton Ocean Model coupled to sea ice. The surface forcing is based on NCEP-NCAR Reanalysis and its climatology, of which the latter is used to force the model spin-up phase. Our focus is to investigate the competition between ocean dynamics and ice formation/melt on the Arctic basin-wide fresh water balance. We find that changes in the Atlantic water inflow can explain almost all of the simulated fresh water anomalies in the main Arctic basin. The Atlantic water inflow anomalies are an essential part of AOO, which is the wind driven barotropic response to the Arctic Oscillation (AO). The baroclinic response to AO, such as Ekman pumping in the Beaufort Gyre, and ice meldfreeze anomalies in response to AO are less significant considering the whole Arctic fresh water balance.

Gender specific reproductive strategies of an arctic key species (Boreogadus saida) and implications of climate change.

PubMed

Nahrgang, Jasmine; Varpe, Oystein; Korshunova, Ekaterina; Murzina, Svetlana; Hallanger, Ingeborg G; Vieweg, Ireen; Berge, Jørgen

2014-01-01

The Arctic climate is changing at an unprecedented rate. What consequences this may have on the Arctic marine ecosystem depends to a large degree on how its species will respond both directly to elevated temperatures and more indirectly through ecological interactions. But despite an alarming recent warming of the Arctic with accompanying sea ice loss, reports evaluating ecological impacts of climate change in the Arctic remain sparse. Here, based upon a large-scale field study, we present basic new knowledge regarding the life history traits for one of the most important species in the entire Arctic, the polar cod (Boreogadus saida). Furthermore, by comparing regions of contrasting climatic influence (domains), we present evidence as to how its growth and reproductive success is impaired in the warmer of the two domains. As the future Arctic is predicted to resemble today's Atlantic domains, we forecast changes in growth and life history characteristics of polar cod that will lead to alteration of its role as an Arctic keystone species. This will in turn affect community dynamics and energy transfer in the entire Arctic food chain.

Evaluation of scour potential of cohesive soils : final report, August 2009.

DOT National Transportation Integrated Search

2009-08-01

Prediction of scour at bridge river crossings is an evolving process. Hydraulic models to estimate water velocity and, therefore, the shear stresses that erode soil are reasonably well developed. The weak link remains methods for estimating soil erod...

Wind-Eroded Silicate as a Source of Hydrogen Peroxide on Mars

NASA Astrophysics Data System (ADS)

Bak, E. N.; Merrison, J. P.; Jensen, S. K.; Nørnberg, P.; Finster, K.

2014-07-01

Laboratory simulations show that wind-eroded silicate can be a source of hydrogen peroxide. The ubiquitous, fine-grained silicate dust might thus explain the oxidizing properties of the martian soil and affect the preservation of organic compounds.

Long-Term Bond Strength of Two Benzalkonium Chloride-Modified Adhesive Systems to Eroded Dentin

PubMed Central

Lussi, Adrian; Peutzfeldt, Anne

2017-01-01

This study investigated the effect of benzalkonium chloride (BAC) modification of two adhesive systems on long-term bond strength to normal and artificially eroded dentin. A total of 128 extracted human molars were sectioned and the buccal and oral surfaces of each molar were ground until the dentin. One half was left untreated (normal dentin) while the other half underwent artificial erosion. Resin composite was bonded to the buccal or oral surface following treatment with Adper Scotchbond 1XT or OptiBond FL without or with 1% BAC incorporation. Shear bond strength (SBS) was measured after 24 h (100% humidity, 37°C) or 1 year (tap water, 37°C). SBS results were statistically analyzed (α = 0.05). SBS was significantly lower to artificially eroded dentin than to normal dentin (p < 0.001). Storage for 1 year had no effect on SBS to normal dentin but led to a significant decrease in SBS to artificially eroded dentin (p < 0.001). BAC incorporation decreased the 24 h SBS to normal dentin (p = 0.018), increased the 24 h SBS to eroded dentin (p = 0.001), and had no effect on the 1-year SBS for either substrate. Consequently, BAC incorporation did not improve bond durability. PMID:28875148

US EPA Region 9 and US Coast Guard Jurisdictional Boundary

EPA Pesticide Factsheets

This line feature represents the jurisdictional boundary along the California coastline that defines EPA (Inland Zone) and Coast Guard (Coastal Zone) emergency response jurisdictions. The U.S. Environmental Protection Agency / U.S. Coast Guard (USEPA / USCG) Jurisdictional Boundary runs from the Oregon to the Mexican border adjacent to the coastline. The boundary was developed from text descriptions provided in the U.S. Environmental Protection Agency Region 9 Mainland Regional Contingency Plan dated March 17, 1994. The Bolsa Chica Ecological Reserve was added to the EPA's jurisdiction in 2011.

Boundary-layer effects on cold fronts at a coastline

NASA Astrophysics Data System (ADS)

Garratt, J. R.

1986-07-01

The present note discusses one physical mechanism which may contribute to cold air channelling, manifest as a frontal bulge on a surface-analysis chart, in the coastal region of Victoria in southeast Australia. This involves the modification of boundary-layer air in both offshore (prefrontal) and onshore (postfrontal) flow, and the effect on cross-frontal thermal contrast. The problem is discussed in terms of a north-south-oriented cold front behaving as an atmospheric gravity current, propagating along an east-west-oriented coastline, in the presence of a prefrontal offshore stream.

Review of technology for Arctic offshore oil and gas recovery. Appendices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sackinger, W. M.

1980-06-06

This volume contains appendices of the following: US Geological Survey Arctic operating orders, 1979; Det Noske Vertas', rules for the design, construction and inspection of offshore technology, 1977; Alaska Oil and Gas Association, industry research projects, March 1980; Arctic Petroleum Operator's Association, industry research projects, January 1980; selected additional Arctic offshore bibliography on sea ice, icebreakers, Arctic seafloor conditions, ice-structures, frost heave and structure icing.

Circumpolar Arctic vegetation: a hierarchic review and roadmap toward an internationally consistent approach to survey, archive and classify tundra plot data

Treesearch

D A Walker; F J A Daniels; I Alsos; U S Bhatt; A L Breen; M Buchhorn; H Bultmann; L A Druckenmiller; M E Edwards; D Ehrich; H E Epstein; William Gould; R A Ims; H Meltofte; M K Raynolds; J Sibik; S S Talbot; P J Webber

2016-01-01

Satellite-derived remote-sensing products are providing a modern circumpolar perspective of Arctic vegetation and its changes, but this new view is dependent on a long heritage of ground-based observations in the Arctic. Several products of the Conservation of Arctic Flora and Fauna are key to our current understanding.Wereview aspects of the PanArctic Flora, the...

An analysis of the carbon balance of the Arctic Basin from 1997 to 2006

Treesearch

A.D. McGuire; D.J. Hayes; D.W. Kicklighter; M. Manizza; Q. Zhuang; M. Chen; M.J. Follows; K.R. Gurney; J.W. McClelland; J.M. Melillo; B.J. Peterson; R.G. Prinn

2010-01-01

This study used several model-based tools to analyze the dynamics of the Arctic Basin between 1997 and 2006 as a linked system of land-ocean-atmosphere C exchange. The analysis estimates that terrestrial areas of the Arctic Basin lost 62.9 Tg C yr-1 and that the Arctic Ocean gained 94.1 Tg C yr-1. Arctic lands and oceans...

Introduction to the 2008 Circum-Arctic Resource Appraisal (CARA) professional paper

USGS Publications Warehouse

Gautier, Donald L.; Moore, Thomas E.; Moore, Thomas E.; Gautier, D.L.

2017-11-15

The amount of yet-to-find oil and gas in the high northern latitudes is one of the great uncertainties of future energy supply. The possibility of extensive new petroleum developments in the Arctic Ocean is of interest to the Arctic nations, to petroleum companies, and to those concerned with the delicate and changing Arctic environment. The U.S. Geological Survey (USGS) 2008 Circum-Arctic Resource Appraisal (CARA) had the express purpose of conducting a geologically based assessment of undiscovered petroleum north of the Arctic Circle, thereby providing an initial evaluation of resource potential. 

Results of an Arctic Council survey on water and sanitation services in the Arctic.

PubMed

Bressler, Jonathan M; Hennessy, Thomas W

2018-12-01

As part of a project endorsed by the Arctic Council's Sustainable Development Working Group (SDWG), a survey was conducted to describe the current status of water, sanitation and hygiene (WASH) services in the Arctic region. The English language internet-based survey was open from April to September, 2016 and drew 142 respondents from seven Arctic nations. Respondents provided information on access to WASH services, notification requirements for water-related infectious diseases, and examples of environmental- or climate-change related events that impact the provision of WASH services. Many remote Arctic and sub-Arctic residents lack WASH services, and these disparities are often not reflected in national summary data. Environmental changes impacting WASH services were reported by respondents in every Arctic nation. Participants at an international conference co-sponsored by SDWG reviewed these results and provided suggestions for next steps to improve health of Arctic residents through improved access to water and sanitation services. Suggestions included ongoing reporting on WASH service availability in underserved populations to measure progress towards UN Sustainable Development Goal #6; evaluations of the health and economic consequences of disparities in WASH services; and Arctic-specific forums to share innovations in WASH technology, improved management and operations, and adaptation strategies for environmental or climate change.

Results of an Arctic Council survey on water and sanitation services in the Arctic

PubMed Central

Bressler, Jonathan M.; Hennessy, Thomas W.

2018-01-01

ABSTRACT As part of a project endorsed by the Arctic Council’s Sustainable Development Working Group (SDWG), a survey was conducted to describe the current status of water, sanitation and hygiene (WASH) services in the Arctic region. The English language internet-based survey was open from April to September, 2016 and drew 142 respondents from seven Arctic nations. Respondents provided information on access to WASH services, notification requirements for water-related infectious diseases, and examples of environmental- or climate-change related events that impact the provision of WASH services. Many remote Arctic and sub-Arctic residents lack WASH services, and these disparities are often not reflected in national summary data. Environmental changes impacting WASH services were reported by respondents in every Arctic nation. Participants at an international conference co-sponsored by SDWG reviewed these results and provided suggestions for next steps to improve health of Arctic residents through improved access to water and sanitation services. Suggestions included ongoing reporting on WASH service availability in underserved populations to measure progress towards UN Sustainable Development Goal #6; evaluations of the health and economic consequences of disparities in WASH services; and Arctic-specific forums to share innovations in WASH technology, improved management and operations, and adaptation strategies for environmental or climate change. PMID:29383987

Early 20th Century Arctic Warming Intensified by Pacific and Atlantic Multidecadal Variability

NASA Astrophysics Data System (ADS)

Tokinaga, H.; Xie, S. P.; Mukougawa, H.

2017-12-01

We investigate the influence of Pacific and Atlantic multidecadal variability on the Arctic temperature, with a particular focus on the early 20th century Arctic warming. Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing than at present. We find that the concurrent phase shift of Pacific and Atlantic multidecadal variability is the major driver for the early 20th century Arctic warming. Atmospheric model simulations reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early Arctic warming is associated with the cold-to-warm phase shifts of Atlantic and Pacific multidecadal variability modes, a SST pattern reminiscent of the positive phase of the Pacific decadal and Atlantic multidecadal oscillations. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. The equatorial Pacific warming deepens the Aleutian low, advecting warm air to the North American Arctic. Coupled ocean-atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, cold-to-warm phase shift of the Pacific and Atlantic multidecadal variability. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region.

Abnormal Winter Melting of the Arctic Sea Ice Cap Observed by the Spaceborne Passive Microwave Sensors

NASA Astrophysics Data System (ADS)

Lee, Seongsuk; Yi, Yu

2016-12-01

The spatial size and variation of Arctic sea ice play an important role in Earth’s climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/ or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).

Integrating Research on Global Climate Change and Human Use of the Oceans: a Geospatial Method for Daily Monitoring of Sea Ice and Ship Traffic in the Arctic

NASA Astrophysics Data System (ADS)

Eucker, W.; McGillivary, P. A.

2012-12-01

One apparent consequence of global climate change has been a decrease in the extent and thickness of Arctic sea ice more rapidly than models have predicted, while Arctic ship traffic has likewise increased beyond economic predictions. To ensure representative observations of changing climate conditions and human use of the Arctic Ocean, we concluded a method of tracking daily changes in both sea ice and shipping in the Arctic Ocean was needed. Such a process improves the availability of sea ice data for navigational safety and allows future developments to be monitored for understanding of ice and shipping in relation to policy decisions appropriate to optimize sustainable use of a changing Arctic Ocean. The impetus for this work was the 2009 Arctic Marine Shipping Assessment (AMSA) which provided baseline data on Arctic ship traffic. AMSA was based on responses from circumpolar countries, was manpower intensive, and took years to compile. A more timely method of monitoring human use of the Arctic Ocean was needed. To address this, a method of monitoring sea ice on a scale relevant to ship-navigation (<10km) was developed and implemented in conjunction with arctic ship tracking using S-AIS (Satellite Automatic Identification Systems). S-AIS is internationally required on ships over a certain size, which includes most commercial vessels in the Arctic Ocean. Daily AIS and sea ice observations were chosen for this study. Results of this method of geospatial analysis of the entire arctic are presented for a year long period from April 1, 2010 to March 31, 2011. This confirmed the dominance of European Arctic ship traffic. Arctic shipping is maximal during August and diminishes in September with a minimum in winter, although some shipping continues year-round in perennially ice-free areas. Data are analyzed for the four principal arctic quadrants around the North Pole by season for number and nationality of vessels. The goal of this study was not merely to monitor ship traffic and ice conditions concurrently, but also to demonstrate a new method of ocean monitoring based on daily assimilation, data fusion, and integrated visualization of satellite ice remote sensing data and S-AIS ship data. In the future, as Arctic ship traffic and cryosphere sea ice cover variability are both expected to increase, this method can provide near real-time physical data on global climate change and human dimensions of ocean use of to guide policies addressing arctic resource management, Search and Rescue (SAR) operations, oil spill response, and issues such as ship noise impacts on marine mammals, and whale-ship collision avoidance. An internationally agreed implementation of this methodology would benefit ships operating in the Arctic and advance sustainable use of the Arctic Ocean.

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

PubMed Central

Tokinaga, Hiroki; Xie, Shang-Ping; Mukougawa, Hitoshi

2017-01-01

With amplified warming and record sea ice loss, the Arctic is the canary of global warming. The historical Arctic warming is poorly understood, limiting our confidence in model projections. Specifically, Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite much weaker greenhouse gas forcing. Here, we show that the concurrent phase shift of Pacific and Atlantic interdecadal variability modes is the major driver for the rapid early 20th-century Arctic warming. Atmospheric model simulations successfully reproduce the early Arctic warming when the interdecadal variability of sea surface temperature (SST) is properly prescribed. The early 20th-century Arctic warming is associated with positive SST anomalies over the tropical and North Atlantic and a Pacific SST pattern reminiscent of the positive phase of the Pacific decadal oscillation. Atmospheric circulation changes are important for the early 20th-century Arctic warming. The equatorial Pacific warming deepens the Aleutian low, advecting warm air into the North American Arctic. The extratropical North Atlantic and North Pacific SST warming strengthens surface westerly winds over northern Eurasia, intensifying the warming there. Coupled ocean–atmosphere simulations support the constructive intensification of Arctic warming by a concurrent, negative-to-positive phase shift of the Pacific and Atlantic interdecadal modes. Our results aid attributing the historical Arctic warming and thereby constrain the amplified warming projected for this important region. PMID:28559341

Trends in the Diversity, Distribution and Life History Strategy of Arctic Hydrozoa (Cnidaria)

PubMed Central

Ronowicz, Marta; Kukliński, Piotr; Mapstone, Gillian M.

2015-01-01

This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia. PMID:25793294

Trends in the diversity, distribution and life history strategy of Arctic Hydrozoa (Cnidaria).

PubMed

Ronowicz, Marta; Kukliński, Piotr; Mapstone, Gillian M

2015-01-01

This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia.

75 FR 58350 - Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-24

... UNITED STATES ARCTIC RESEARCH COMMISSION Meeting Notice is hereby given that the U.S. Arctic... reports. (4) Discussion and presentations concerning Arctic research activities. The focus of the meeting will be reports and updates on programs and research projects affecting the Arctic. If you plan to...

Multinational Experiment 7. Maritime Security Region: The Arctic

DTIC Science & Technology

2013-07-08

Russia. Marine Resources The Arctic Ocean is home to countless species from microscopic plankton to gigantic whales . Large-scale commercial...Arctic is a circumpolar region that encompasses both marine and land masses and includes the Arctic Ocean and its seas that cover more than 30...and does not rise on the day of the winter solstice. The Arctic Ocean is the world’s smallest and shallowest, with an average depth of roughly a

Biological Environmental Arctic Project (BEAP) Preliminary Data (Arctic West Summer 1986 Cruise).

DTIC Science & Technology

1986-11-01

predictive model of bioluminescence in near-surface arctic waters . Data were collected during Arctic West Summer 1986 from USCG POLAR STAR (WAGB 10). . %. J...2 20ODISTRIBUTION AVAILABILIT "Y OF ABSTRACT 21 ABSTRACT SECURITY CLASSIFICATION C]UNCLASSIFIED UNLIMITED SAME AS RPT C] DTIC USERS UNCLASSIFIED David...correlates for a predictive model of bioluminescence in near-surface arctic waters . - In previous years, these measurements were conducted from the USCG

Assessing and Predicting Erosion from Off Highway Vehicle Trails in Front-Range Rocky Mountain Watersheds.

NASA Astrophysics Data System (ADS)

Howard, M. J.; Silins, U.; Anderson, A.

2016-12-01

Off highway vehicle (OHV) trails have the potential to deliver sediment to sensitive headwater streams and increased OHV use is a growing watershed management concern in many Rocky Mountain regions. Predictive tools for estimating erosion and sediment inputs are needed to support assessment and management of erosion from OHV trail networks. The objective of this study was to a) assess erodibility (K factor) and total erosion from OHV trail networks in Rocky Mountain watersheds in south-west Alberta, Canada, and to b) evaluate the applicability of the Universal Soil Loss Equation (USLE) for predicting OHV trail erosion to support erosion management strategies. Measured erosion rates and erodibility (K) from rainfall simulation plots on OHV trails during the summers of 2014 and 2015 were compared to USLE predicted erosion from these same trails. Measured erodibility (K) from 23 rainfall simulation plots was highly variable (0.001-0.273 Mg*ha*hr/ha*MJ*mm) as was total seasonal erosion from 52 large trail sections (0.0595-43.3 Mg/ha) across trail segments of variable slope, stoniness, and trail use intensity. In particular, intensity of trail use had a large effect on both erodibility and total erosion that is not presently captured by erodibility indices (K) derived from soil characteristics. Results of this study suggest that while application of USLE for predicting erosion from OHV trail networks may be useful for initial coarse erosion assessment, a better understanding of the effect of factors such as road/trail use intensity on erodibility is needed to support use of USLE or associated erosion prediction tools for road/trail erosion management.

Erodibility of calcareous soils as influenced by land use and intrinsic soil properties in a semiarid region of central Iran.

PubMed

Ayoubi, Shamsollah; Mokhtari, Javad; Mosaddeghi, Mohammad Reza; Zeraatpisheh, Mojtaba

2018-03-06

The most important properties affecting the soil loss and runoff were investigated, and the effects of land use on the soil properties, together with the erodibility indices in a semiarid zone, central Iran, were evaluated. The locations of 100 positions were acquired by cLHS and 0-5-cm surface soil layer samples were used for laboratory analyses from the Borujen Region, Chaharmahal-Va-Bakhtiari Province, central Iran. To measure in situ runoff and soil erodibility of three different land uses comprising dryland, irrigated farming, and rangeland, a portable rainfall simulator was used. The results showed that the high variations (coefficient of variation, CV) were obtained for electrical conductivity (EC), mean weight diameter (MWD), soil organic carbon (SOC), and soil erodibility indices including runoff volume, soil loss, and sediment concentration (CV ~ 43.6-77.4%). Soil erodibility indices showed positive and significant correlations with bulk density and negative correlations with SOC, MWD, clay content, and soil shear strength in the area under investigation. The values of runoff in the dryland, irrigated farming, and rangeland were found 1.5, 28.9, and 58.7 cm 3 ; soil loss in the dryland, irrigated farming, and rangeland were observed 0.25, 2.96, and 76.8 g; and the amount of sediment concentration in the dryland, irrigated farming, and rangeland were found 0.01, 0.11, and 0.15 g cm -3 . It is suggested that further investigations should be carried out on soil erodibility and the potential of sediment yield in various land uses with varying topography and soil properties in semiarid regions of Iran facing the high risk of soil loss.

In vitro cellular responses in the RTG-2 cell line to complex mixtures of dioxins and dioxin-like PCDDs, PCDFs and PCBs.

PubMed

Babín, María del Mar; Sanz, Paloma; Concejero, Miguel Angel; Martínez, María Angeles; Tarazona, José Vicente

2010-08-01

High-resolution gas chromatography/mass spectrometry (HRGC/MS) is the standard method for analysing dioxin, furan and polybrominated retardants in hazardous waste. Determination of dioxin-like compounds using in vitro bioassays such as ethoxyresorufin-O-deethylase (EROD) is an important tool to evaluate their Ah receptor-mediated toxic effects, because it detects all arylhydrocarbon receptor ligands in a variety of sample matrices. In the present work, we compared RTG-2 cell line EROD bioassay with HRGC/MS for assessing waste samples (liquid and solid) contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls (dioxin-like PCBs) and other xenobiotics. For liquid samples, HRGC/MS-toxic equivalent (HRGC/MS-TEQ) values ranged from 273.26 to 5.84 ng TEQ l(-1) and correlated well (correlation coefficient 0.99) with values obtained by EROD-TEQ, which ranged from 128 to 2.5 ng TEQ l(-1). For solid samples, HRGC/MS-TEQ values ranged from 3.44 to 0.49 ng TEQ g(-1) and correlated less well than liquid samples (correlation coefficient 0.64) with values obtained by EROD-TEQ ranging from 2.27 to 0.93 ng TEQ g(-1). The overestimation of RTG-2 EROD-TEQ (1.2 +/- 0.92 of values established by HRGC/MS) and the absence of false-negative results may limit analytical costs by eliminating the need for follow-up GC/MS analysis on the negative samples. We suggest that RTG-2 EROD bioassay is an inexpensive means for preliminary dioxin and furan positive screenings of waste samples. (c) 2010 John Wiley & Sons, Ltd.

Structural features of cytochrome P450 1A associated with the absence of EROD activity in liver of the of the loricariid catfish Pterygoplichthys sp

PubMed Central

Parente, T.E.M.; Rebelo, M.F.; da-Silva, M.L.; Woodin, B.R.; Goldstone, J. V.; Bisch, P.M.; Paumgartten, F.J.R.; Stegeman, J.J.

2011-01-01

The Amazon catfish genus Pterygoplichthys (Loricariidae, Siluriformes) is closely related to the loricariid genus Hypostomus, in which at least two species lack detectable ethoxyresorufin-O-deethylase (EROD) activity, typically catalyzed by cytochrome P450 1 (CYP1) enzymes. Pterygoplichthys sp. liver microsomes also lacked EROD, as well as activity with other substituted resorufins, but aryl hydrocarbon receptor agonists induced hepatic CYP1A mRNA and protein suggesting structural/functional differences in Pterygoplichthys CYP1s from those in other vertebrates. Comparing the sequences of CYP1As of Pterygoplichthys sp. and of two phylogenetically-related siluriform species that do catalyze EROD (Ancistrus sp., Loricariidae and Corydoras sp., Callichthyidae) showed that these three proteins share amino acids at 17 positions that are not shared by any fish in a set of 24 other species. Pterygoplichthys and Ancistrus (the loricariids) have an additional 22 amino acid substitutions in common that are not shared by Corydoras or by other fish species. Pterygoplichthys has six exclusive amino acid substitutions. Molecular docking and dynamics simulations indicate that Pterygoplichthys CYP1A has a weak affinity for ER, which binds infrequently in a productive orientation, and in a less stable conformation than in CYP1As of species that catalyze EROD. ER also binds with the carbonyl moiety proximal to the heme iron. Pterygoplichthys CYP1A has amino acids substitutions that reduce the frequency of correctly oriented ER in the AS preventing the detection of EROD activity. The results indicate that loricariid CYP1As may have a peculiar substrate selectivity that differs from CYP1As of most vertebrates. PMID:21840383

Structural features of cytochrome P450 1A associated with the absence of EROD activity in liver of the loricariid catfish Pterygoplichthys sp.

PubMed

Parente, Thiago E M; Rebelo, Mauro F; da-Silva, Manuela L; Woodin, Bruce R; Goldstone, Jared V; Bisch, Paulo M; Paumgartten, Francisco J R; Stegeman, John J

2011-12-10

The Amazon catfish genus Pterygoplichthys (Loricariidae, Siluriformes) is closely related to the loricariid genus Hypostomus, in which at least two species lack detectable ethoxyresorufin-O-deethylase (EROD) activity, typically catalyzed by cytochrome P450 1 (CYP1) enzymes. Pterygoplichthys sp. liver microsomes also lacked EROD, as well as activity with other substituted resorufins, but aryl hydrocarbon receptor agonists induced hepatic CYP1A mRNA and protein suggesting structural/functional differences in Pterygoplichthys CYP1s from those in other vertebrates. Comparing the sequences of CYP1As of Pterygoplichthys sp. and of two phylogenetically related siluriform species that do catalyze EROD (Ancistrus sp., Loricariidae and Corydoras sp., Callichthyidae) showed that these three proteins share amino acids at 17 positions that are not shared by any fish in a set of 24 other species. Pterygoplichthys and Ancistrus (the loricariids) have an additional 22 amino acid substitutions in common that are not shared by Corydoras or by other fish species. Pterygoplichthys has six exclusive amino acid substitutions. Molecular docking and dynamics simulations indicate that Pterygoplichthys CYP1A has a weak affinity for ER, which binds infrequently in a productive orientation, and in a less stable conformation than in CYP1As of species that catalyze EROD. ER also binds with the carbonyl moiety proximal to the heme iron. Pterygoplichthys CYP1A has amino acid substitutions that reduce the frequency of correctly oriented ER in the AS preventing the detection of EROD activity. The results indicate that loricariid CYP1As may have a peculiar substrate selectivity that differs from CYP1As of most vertebrate. Copyright © 2011 Elsevier B.V. All rights reserved.

Quantifying the eroded volume of mercury-contaminated sediment using terrestrial laser scanning at Stocking Flat, Deer Creek, Nevada County, California, 2010–13

USGS Publications Warehouse

Howle, James F.; Alpers, Charles N.; Bawden, Gerald W.; Bond, Sandra

2016-07-28

High-resolution ground-based light detection and ranging (lidar), also known as terrestrial laser scanning, was used to quantify the volume of mercury-contaminated sediment eroded from a stream cutbank at Stocking Flat along Deer Creek in the Sierra Nevada foothills, about 3 kilometers west of Nevada City, California. Terrestrial laser scanning was used to collect sub-centimeter, three-dimensional images of the complex cutbank surface, which could not be mapped non-destructively or in sufficient detail with traditional surveying techniques.The stream cutbank, which is approximately 50 meters long and 8 meters high, was surveyed on four occasions: December 1, 2010; January 20, 2011; May 12, 2011; and February 4, 2013. Volumetric changes were determined between the sequential, three-dimensional lidar surveys. Volume was calculated by two methods, and the average value is reported. Between the first and second surveys (December 1, 2010, to January 20, 2011), a volume of 143 plus or minus 15 cubic meters of sediment was eroded from the cutbank and mobilized by Deer Creek. Between the second and third surveys (January 20, 2011, to May 12, 2011), a volume of 207 plus or minus 24 cubic meters of sediment was eroded from the cutbank and mobilized by the stream. Total volumetric change during the winter and spring of 2010–11 was 350 plus or minus 28 cubic meters. Between the third and fourth surveys (May 12, 2011, to February 4, 2013), the differencing of the three-dimensional lidar data indicated that a volume of 18 plus or minus 10 cubic meters of sediment was eroded from the cutbank. The total volume of sediment eroded from the cutbank between the first and fourth surveys was 368 plus or minus 30 cubic meters.

Distribution of Aerosols in the Arctic as Observed by CALIOP

NASA Astrophysics Data System (ADS)

Winker, D.; Kittaka, C.

2007-12-01

The Arctic climate is now recognized to be uniquely sensitive to atmospheric perturbations. Pollution aerosols and smoke from boreal fires have potentially important impacts on Arctic climate but there are many uncertainties. Aerosol in the Arctic, generally referred to as "Arctic haze", has been studied with great interest for over thirty years. Much has been learned about the composition and sources of the haze yet our knowledge is largely based on long term measurements at a very few widely dispersed sites, augmented by modeling activities and occasional field campaigns. Transport pathways from source regions into the Arctic are not well understood. Emission patterns have changed over the last several decades, but the impact of this on concentrations and distribution of Arctic haze are understood only in the crudest sense. Due to poor lighting conditions, extended periods of darkness, and surfaces covered by snow and ice, satellite sensors have been unable to provide much information on Arctic haze to date. The CALIPSO satellite carries CALIOP, a two-wavelength polarization lidar, optimized for profiling clouds and aerosols. CALIOP has been acquiring global observations since June 2006 and provides our first opportunity to observe the distribution and seasonal variation of aerosol in the Arctic. The Arctic is characterized by the prevalence of optically thin ice clouds and clouds composed of supercooled water, often occurring in the same atmospheric column along with aerosol. CALIOP depolarization signals are used to discriminate Arctic haze from optically thin cirrus and diamond dust. Two-wavelength returns aid in the discrimination of aerosol and optically thin water cloud. Results of initial analyses of CALIOP aerosol observations in the Arctic will be presented. This work is a preliminary analysis in support of the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign planned for April 2008.