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Sediment Transport Model Including Short-Lived Radioisotopes: Model Description And Idealized Test Cases, Justin J. Birchler,, Courtney K. Harris, Christopher R Sherwood, Tara A. Kniskern
Sediment Transport Model Including Short-Lived Radioisotopes: Model Description And Idealized Test Cases, Justin J. Birchler,, Courtney K. Harris, Christopher R Sherwood, Tara A. Kniskern
VIMS Articles
Geochronologies derived from sediment cores in coastal locations are often used to infer event bed characteristics such as deposit thicknesses and accumulation rates. Such studies commonly use naturally occurring, short-lived radioisotopes, such as Beryllium-7 (Be-7) and Thorium-234 (Th-234), to study depositional and post-depositional processes. These radioisotope activities, however, are not generally represented in sediment transport models that characterize coastal flood and storm deposition with grain size patterns and deposit thicknesses. We modified the Community Sediment Transport Modeling System (CSTMS) to account for reactive tracers and used this capability to represent the behavior of these short-lived radioisotopes on the sediment bed. …
Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Rachel E. Sipler, M. M. Mills, D. A. Bronk
Symbiotic Unicellular Cyanobacteria Fix Nitrogen In The Arctic Ocean, K. Harding, K. A. Turk-Kubo, Rachel E. Sipler, M. M. Mills, D. A. Bronk
VIMS Articles
Biological dinitrogen (N2) fixation is an important source of nitrogen (N) in low-latitude open oceans. The unusual N2-fixing unicellular cyanobacteria (UCYN-A)/haptophyte symbiosis has been found in an increasing number of unexpected environments, including northern waters of the Danish Straight and Bering and Chukchi Seas. We used nanoscale secondary ion mass spectrometry (nanoSIMS) to measure 15N2 uptake into UCYN-A/haptophyte symbiosis and found that UCYN-A strains identical to low-latitude strains are fixing N2 in the Bering and Chukchi Seas, at rates comparable to subtropical waters. These results show definitively that cyanobacterial N2 fixation is not constrained to subtropical waters, challenging paradigms and …
Stormsense: A Blueprint For Coastal Flood Forecast Information & Automated Alert Messaging Systems, Jon Derek Loftis, Sridhar Katragadda, Sokwoo Rhee, Cuong Nguyen
Stormsense: A Blueprint For Coastal Flood Forecast Information & Automated Alert Messaging Systems, Jon Derek Loftis, Sridhar Katragadda, Sokwoo Rhee, Cuong Nguyen
VIMS Articles
Increased availability of low-cost water level sensors communicating through the Internet of Things (IoT) has expanded the horizons of publicly-ingestible data streams available to modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA for flooding resulting from storm surge, rain, and tides. In this study, we present the a blueprint and series of applicable protocols through the use of the new StormSense water level sensors to help establish a regional resilience monitoring network. In furtherance …
Effects Of Density‐Driven Flows On The Long‐Term Morphodynamic Evolution Of Funnel‐Shaped Estuaries, Matiane Olabarrieta, W. Rockwell Geyer, Giovanni Coco, Carl T. Friedrichs
Effects Of Density‐Driven Flows On The Long‐Term Morphodynamic Evolution Of Funnel‐Shaped Estuaries, Matiane Olabarrieta, W. Rockwell Geyer, Giovanni Coco, Carl T. Friedrichs
VIMS Articles
Subtidal flows driven by density gradients affect the tide‐averaged sediment transport in estuaries and, therefore, can influence their long‐term morphodynamic evolution. The three‐dimensional Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport modeling system is applied to numerically analyze the effects of baroclinicity and Earth's rotation on the long‐term morphodynamic evolution of idealized funnel‐shaped estuaries. The morphodynamic evolution in all the analyzed cases reproduced structures identified in many tide‐dominated estuaries: a meandering region in the fluvial‐tidal transition zone, a tidal maximum area close to the head, and a turbidity maxima region in the brackish zone. As the morphology of the estuaries evolved, the tidal propagation (including …
Impact Of Seabed Resuspension On Oxygen And Nitrogen Dynamics In The Northern Gulf Of Mexico: A Numerical Modeling Study, Julia M. Moriarty, Courtney K. Harris, Marjorie A.M. Friedrichs, Katja Fennel, Kehui Xu
Impact Of Seabed Resuspension On Oxygen And Nitrogen Dynamics In The Northern Gulf Of Mexico: A Numerical Modeling Study, Julia M. Moriarty, Courtney K. Harris, Marjorie A.M. Friedrichs, Katja Fennel, Kehui Xu
VIMS Articles
Resuspension affects water quality in coastal environments by entraining seabed organic matter into the water column, which can increase remineralization, alter seabed fluxes, decrease water clarity, and affect oxygen and nutrient dynamics. Nearly all numerical models of water column biogeochemistry, however, simplify seabed and bottom boundary layer processes and neglect resuspension. Here we implemented HydroBioSed, a coupled hydrodynamic-sediment transport-biogeochemical model to examine the role of resuspension in regulating oxygen and nitrogen dynamics on timescales of a day to a month. The model was implemented for the northern Gulf of Mexico, where the extent of summertime hypoxia is sensitive to seabed …
Overcoming Early Career Barriers To Interdisciplinary Climate Change Research, Christopher J. Hein, John E. Ten Hoeve, Sathya Gopalakrishnan, Et Al
Overcoming Early Career Barriers To Interdisciplinary Climate Change Research, Christopher J. Hein, John E. Ten Hoeve, Sathya Gopalakrishnan, Et Al
VIMS Articles
Climate-change impacts are among the most serious and complex challenges facing society, affecting both natural and social systems. Addressing these requires a new paradigm of interdisciplinary collaboration which incorporates tools, techniques, and insights from across the social, natural, and engineering sciences. Yet, a wide range of intrinsic and extrinsic hurdles need to be overcome to conduct successful, integrated interdisciplinary research. The results of a bibliometric analysis and survey of early to mid-career scientists from 56 countries who were involved with the interdisciplinary DISsertations initiative for the advancement of Climate Change ReSearch (DISCCRS) emphasize the particular challenges faced by early career …
Future Response Of Global Coastal Wetlands To Sea-Level Rise, M. Schuerch, T. Spencer, S. Temmerman, Matthew L. Kirwan, Et Al
Future Response Of Global Coastal Wetlands To Sea-Level Rise, M. Schuerch, T. Spencer, S. Temmerman, Matthew L. Kirwan, Et Al
VIMS Articles
The response of coastal wetlands to sea-level rise during the twenty-first century remains uncertain. Global-scale projections suggest that between 20 and 90 per cent (for low and high sea-level rise scenarios, respectively) of the present-day coastal wetland area will be lost, which will in turn result in the loss of biodiversity and highly valued ecosystem services(1-3). These projections do not necessarily take into account all essential geomorphological(4-7) and socio-economic system feedbacks(8). Here we present an integrated global modelling approach that considers both the ability of coastal wetlands to build up vertically by sediment accretion, and the accommodation space, namely, the …
The Contribution Of Local And Transport Processes To Phytoplankton Biomass Variability Over Different Timescales In The Upper James River, Virginia, Qubin Quin, Jian Shen
The Contribution Of Local And Transport Processes To Phytoplankton Biomass Variability Over Different Timescales In The Upper James River, Virginia, Qubin Quin, Jian Shen
VIMS Articles
Although both local processes (photosynthesis, respiration, grazing, and settling), and transport processes (advective transport and diffusive transport) significantly affect local phytoplankton dynamics, it is difficult to separate their contributions and to investigate the relative importance of each process to the local variability of phytoplankton biomass over different timescales. A method of using the transport rate is introduced to quantify the contribution of transport processes. By combining the time-varying transport rate and high-frequency observed chlorophyll a data, we can explicitly examine the impact of local and transport processes on phytoplankton biomass over a range of timescales from hourly to annually. For …
Stoichiometric N:P Ratios, Temperature, And Iron Impact Carbon And Nitrogen Uptake By Ross Sea Microbial Communities, Jl Spackeen, Da Bronk, Rachel E. Sipler, Em Bertrand, Da Hutchins, Ae Allen
Stoichiometric N:P Ratios, Temperature, And Iron Impact Carbon And Nitrogen Uptake By Ross Sea Microbial Communities, Jl Spackeen, Da Bronk, Rachel E. Sipler, Em Bertrand, Da Hutchins, Ae Allen
VIMS Articles
The Southern Ocean is one of the most biologically important ecosystems on our planet. Microscopic plants, called phytoplankton, form the base of the food web in the Southern Ocean and play a direct role in regulating how much and how fast elements like nitrogen and carbon are cycled throughout the world ocean. The goal of this research was to determine how predicted changes in the environment will impact how fast phytoplankton use these elements. The conditions that we tested included elevated temperature, addition of iron, and the proportion of nitrogen to phosphorus in the seawater. These parameters were selected because …
Estimating Hypoxic Volume In The Chesapeake Bay Using Two Continuously Sampled Oxygen Profiles, Aaron J. Bever, Marjorie A.M. Friedrichs, Carl T. Friedrichs, Malcolm E. Scully
Estimating Hypoxic Volume In The Chesapeake Bay Using Two Continuously Sampled Oxygen Profiles, Aaron J. Bever, Marjorie A.M. Friedrichs, Carl T. Friedrichs, Malcolm E. Scully
VIMS Articles
Low levels of dissolved oxygen (DO) occur in many embayments throughout the world and have numerous detrimental effects on biota. Although measurement of in situ DO is straightforward with modern instrumentation, quantifying the volume of water in a given embayment that is hypoxic (hypoxic volume (HV)) is a more difficult task; however, this information is critical for determining whether management efforts to increase DO are having an overall impact. This paper uses output from a three‐dimensional numerical model to demonstrate that HV in Chesapeake Bay can be estimated well with as few as two vertical profiles. In addition, the cumulative …
Role Of Sediment Resuspension On Estuarine Suspended Particulate Mercury Dynamics, Ea Seelen, Grace M. Massey, Rp Mason
Role Of Sediment Resuspension On Estuarine Suspended Particulate Mercury Dynamics, Ea Seelen, Grace M. Massey, Rp Mason
VIMS Articles
Coastal sediments are an important site for transient and long-term mercury (Hg) storage, and they foster a geochemical environment optimal for Hg methylation. Therefore, efforts have been taken to constrain the role of sediments as a source of methylmercury (MeHg) to the estuarine water column. This study employed the Gust Microcosm Erosion Core system capable of quantifying particle removal from undisturbed cores under measurable shear stress conditions to assess particulate Hg and MeHg exchange between sediments and the water column. Samples were collected from organic-rich and organic-poor sediment types from the mid- and lower Delaware Bay. It was found that …
A 3d Unstructured-Grid Model For Chesapeake Bay: Importance Of Bathymetry, Fei Ye, Yinglong J. Zhang, Harry V. Wang, Marjorie A.M. Friedrichs, Isaac D. Irby, Eli Alteljevich, Arnaldo Valle-Levinson, Zhengui Wang, Hai Huang, Jian Shen, Jiabi Du
A 3d Unstructured-Grid Model For Chesapeake Bay: Importance Of Bathymetry, Fei Ye, Yinglong J. Zhang, Harry V. Wang, Marjorie A.M. Friedrichs, Isaac D. Irby, Eli Alteljevich, Arnaldo Valle-Levinson, Zhengui Wang, Hai Huang, Jian Shen, Jiabi Du
VIMS Articles
We extend the 3D unstructured-grid model previously developed for the Upper Chesapeake Bay to cover the entire Bay and its adjacent shelf, and assess its skill in simulating saltwater intrusion and the coastal plume. Recently developed techniques, including a flexible vertical grid system and a 2nd-order, monotone and implicit transport solver are critical in successfully capturing the baroclinic responses. Most importantly, good accuracy is achieved through an accurate representation of the underlying bathymetry, without any smoothing. The model in general exhibits a good skill for all hydrodynamic variables: the averaged root-mean-square errors (RMSE‟s) in the Bay are 9 cm for …
Role Of Baroclinic Processes On Flushing Characteristics In A Highly Stratified Estuarine System, Mobile Bay, Alabama, Jiabi Du, Kyeong Park, Jian Shen, Et Al
Role Of Baroclinic Processes On Flushing Characteristics In A Highly Stratified Estuarine System, Mobile Bay, Alabama, Jiabi Du, Kyeong Park, Jian Shen, Et Al
VIMS Articles
Flushing of an estuary quantifies the overall water exchange between the estuary and coastal ocean and is crucially important for water quality as well as biological and geochemical processes within the system. Flushing times and freshwater age in Mobile Bay were numerically calculated under realistic and various controlled forcing conditions. Their responses to external forcing were explained by the three‐dimensional characteristics of general circulation in the system. The flushing time ranges from 10 to 33 days under the 25th–75th percentile river discharges, nearly half of the previous estimates based on barotropic processes only, suggesting the important contribution of baroclinic processes. …
Effects Of Marsh Edge Erosion In Coupled Barrier Island-Marsh Systems And Geometric Constraints On Marsh Evolution, Rebecca Lauzon, A Brad Murray, Laura J Moore, David C. Walters, Matthew L. Kirwan, Sergio Fagherazzi,
Effects Of Marsh Edge Erosion In Coupled Barrier Island-Marsh Systems And Geometric Constraints On Marsh Evolution, Rebecca Lauzon, A Brad Murray, Laura J Moore, David C. Walters, Matthew L. Kirwan, Sergio Fagherazzi,
VIMS Articles
Sand washed across barrier islands during storms (called overwash) provides sediment for salt marshes behind those islands, and can allow a marsh which otherwise would drown to grow vertically fast enough to keep up with sea level. We use a barrier island-marsh evolution model (GEOMBEST+) to see what effect marsh edge erosion by waves has on overwash-supported marshes. Consistent with previous research, we find that wave erosion can make marshes more resilient by freeing sediment that can be used elsewhere on the marsh surface. We add that horizontal erosion of the marsh edge provides more sediment per volume eroded than …
Tidal Response To Sea-Level Rise In Different Types Of Estuaries: The Importance Of Length, Bathymetry, And Geometry, Jb Du, Jian Shen, Yinglong J. Zhang, Fei Ye, Z Liu, Zg Wang, Yp Wang, X Yu, M Sisson, Harry V. Wang
Tidal Response To Sea-Level Rise In Different Types Of Estuaries: The Importance Of Length, Bathymetry, And Geometry, Jb Du, Jian Shen, Yinglong J. Zhang, Fei Ye, Z Liu, Zg Wang, Yp Wang, X Yu, M Sisson, Harry V. Wang
VIMS Articles
Tidal response to sea-level rise (SLR) varies in different coastal systems. To provide a generic pattern of tidal response to SLR, a systematic investigation was conducted using numerical techniques applied to idealized and realistic estuaries, with model results cross-checked by analytical solutions. Our results reveal that the response of tidal range to SLR is nonlinear, spatially heterogeneous, and highly affected by the length and bathymetry of an estuary and weakly affected by the estuary convergence with an exception of strong convergence. Contrary to the common assumption that SLR leads to a weakened bottom friction, resulting in increased tidal amplitude, we …
Integrated Ocean, Earth, And Atmospheric Observations For Resilience Planning In Hampton Roads, Virginia, Jon Derek Loftis, Molly Mitchell, Larry Atkinson, Ben Hamlington, Thomas R. Allen, David R. Forrest, Et Al
Integrated Ocean, Earth, And Atmospheric Observations For Resilience Planning In Hampton Roads, Virginia, Jon Derek Loftis, Molly Mitchell, Larry Atkinson, Ben Hamlington, Thomas R. Allen, David R. Forrest, Et Al
VIMS Articles
Building flood resilience in coastal communities requires a precise understanding of the temporal and spatial scales of inundation and the ability to detect and predict changes in flooding. In Hampton Roads, the Intergovernmental Pilot Project's Scientific Advisory Committee recommended an integrated network of ocean, earth, and atmospheric data collection from both private and public sector organizations that engage in active scientific monitoring and observing. Since its establishment, the network has grown to include monitoring of water levels, land subsidence, wave measurements, current measurements, and atmospheric conditions. High-resolution land elevation and land cover data sets have also been developed. These products …
Stormsense: A New Integrated Network Of Iot Water Level Sensors In The Smart Cities Of Hampton Roads, Va, Jon Derek Loftis, David R. Forrest, Sridhar Katragadda, Kyle Spencer, Tammie Organski, Cuong Nguyen, Sokwoo Rhee
Stormsense: A New Integrated Network Of Iot Water Level Sensors In The Smart Cities Of Hampton Roads, Va, Jon Derek Loftis, David R. Forrest, Sridhar Katragadda, Kyle Spencer, Tammie Organski, Cuong Nguyen, Sokwoo Rhee
VIMS Articles
Propagation of cost-effective water level sensors powered through the Internet of Things (IoT) has expanded the available offerings of ingestible data streams at the disposal of modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge, seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA, for flooding resulting from storm surge, rain, and tides. In this study, we present the results of the new StormSense water level sensors to help establish the “regional resilience monitoring network” noted as a key recommendation from the Intergovernmental Pilot …
Accuracy And Precision Of Tidal Wetland Soil Carbon Mapping In The Conterminous United States, Jr Holmquist, L Windham-Myers, N Bliss, S Crooks, Jt Morris, W. G. Reay, Et Al.
Accuracy And Precision Of Tidal Wetland Soil Carbon Mapping In The Conterminous United States, Jr Holmquist, L Windham-Myers, N Bliss, S Crooks, Jt Morris, W. G. Reay, Et Al.
VIMS Articles
Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils …
Spatial Distribution And Morphological Responses To Predation In The Salt Marsh Periwinkle, Aj Rietl, Mg Sorrentino, Bj Roberts
Spatial Distribution And Morphological Responses To Predation In The Salt Marsh Periwinkle, Aj Rietl, Mg Sorrentino, Bj Roberts
VIMS Articles
The salt marsh periwinkle (Littoraria irrorata) is a common and often abundant mollusk in marshes of the Gulf and Atlantic coasts of the United States. Several studies have focused on the effects of periwinkles on Spartina alterniflora production and the effects of oil on periwinkle survivability, yet the general ecology of the snail has been underreported. In this study, we measured spatial distributions, biomass, shell repair frequency, and a suite of morphological characteristics of L. irrorata at three sites in each of five regions spanning the southeastern Louisiana Coast between the Atchafalaya and Mississippi rivers. Sampling was conducted along 50 …
Time Trends Of Polybrominated Diphenyl Ethers (Pbdes) In Antarctic Biota, E Markham, Ek Brault, M Khairy, Ar Robuck, Me Goebel, Mg Cantwell, Rm Dickhut, R Lohmann
Time Trends Of Polybrominated Diphenyl Ethers (Pbdes) In Antarctic Biota, E Markham, Ek Brault, M Khairy, Ar Robuck, Me Goebel, Mg Cantwell, Rm Dickhut, R Lohmann
VIMS Articles
Polybrominated diphenyl ethers (PBDEs) are "emerged" contaminants that were produced and used as flame retardants in numerous consumer and industrial applications for decades until banned. They remain ubiquitously present in the environment today. Here, a unique set of >200 biotic samples from the Antarctic was analyzed for PBDEs, including phytoplankton, krill, fish, and fur seal milk, spanning several sampling seasons over 14 years. PBDE-47 and -99 were the dominant congeners determined in all samples, constituting > 60% of total PBDEs. A temporal trend was observed for Sigma 7PBDE concentrations in fur seal milk, where concentrations significantly increased (R-2 = 0.57, p < 0.05) over time (2000-2014). Results for krill and phytoplankton also suggested increasing PBDE concentrations over time. Trends of PBDEs in fur seal milk of individual seals sampled 1 or more years apart showed no clear temporal trends. Overall, there was no indication of PBDEs decreasing in Antarctic biota yet, whereas numerous studies have reported decreasing trends in the northern hemisphere. Similar PBDE concentrations in perinatal versus nonperinatal milk implied the importance of local PBDE sources for bioaccumulation. These results indicate the need for continued assessment of contaminant trends, such as PBDEs, and their replacements, in Antarctica.
Cohesive And Mixed Sediment In The Regional Ocean Modeling System (Roms V3.6) Implemented In The Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System (Coawst R1234), Cr Sherwood, Al Aretxabaleta, Courtney K. Harris, Jp Rinehimer, R Verney, B Ferre
Cohesive And Mixed Sediment In The Regional Ocean Modeling System (Roms V3.6) Implemented In The Coupled Ocean-Atmosphere-Wave-Sediment Transport Modeling System (Coawst R1234), Cr Sherwood, Al Aretxabaleta, Courtney K. Harris, Jp Rinehimer, R Verney, B Ferre
VIMS Articles
We describe and demonstrate algorithms for treating cohesive and mixed sediment that have been added to the Regional Ocean Modeling System (ROMS version 3.6), as implemented in the Coupled Ocean-Atmosphere-Wave- Sediment Transport Modeling System (COAWST Subversion repository revision 1234). These include the following: floc dynamics (aggregation and disaggregation in the water column); changes in floc characteristics in the seabed; erosion and deposition of cohesive and mixed (combination of cohesive and non-cohesive) sediment; and biodiffusive mixing of bed sediment. These routines supplement existing noncohesive sediment modules, thereby increasing our ability to model fine-grained and mixed-sediment environments. Additionally, we describe changes to …
The Competing Impacts Of Climate Change And Nutrient Reductions On Dissolved Oxygen In Chesapeake Bay, Id Irby, Marjorie A.M. Friedrichs, F Da, Ke Hinson
The Competing Impacts Of Climate Change And Nutrient Reductions On Dissolved Oxygen In Chesapeake Bay, Id Irby, Marjorie A.M. Friedrichs, F Da, Ke Hinson
VIMS Articles
The Chesapeake Bay region is projected to experience changes in temperature, sea level, and precipitation as a result of climate change. This research uses an estuarine-watershed hydrodynamic-biogeochemical modeling system along with projected mid-21st-century changes in temperature, freshwater flow, and sea level rise to explore the impact climate change may have on future Chesapeake Bay dissolved-oxygen (DO) concentrations and the potential success of nutrient reductions in attaining mandated estuarine water quality improvements. Results indicate that warming bay waters will decrease oxygen solubility year-round, while also increasing oxygen utilization via respiration and remineralization, primarily impacting bottom oxygen in the spring. Rising sea …
Assimilating Bio-Optical Glider Data During A Phytoplankton Bloom In The Southern Ross Sea, De Kaufman, Marjorie A.M. Friedrichs, Jcp Hemmings, Walker O. Smith Jr.
Assimilating Bio-Optical Glider Data During A Phytoplankton Bloom In The Southern Ross Sea, De Kaufman, Marjorie A.M. Friedrichs, Jcp Hemmings, Walker O. Smith Jr.
VIMS Articles
The Ross Sea is a region characterized by high primary productivity in comparison to other Antarctic coastal regions, and its productivity is marked by considerable variability both spatially (1-50 km) and temporally (days to weeks). This variability presents a challenge for inferring phytoplankton dynamics from observations that are limited in time or space, which is often the case due to logistical limitations of sampling. To better understand the spatio-temporal variability in Ross Sea phytoplankton dynamics and to determine how restricted sampling may skew dynamical interpretations, high-resolution bio-optical glider measurements were assimilated into a one-dimensional biogeochemical model adapted for the Ross …
Early-Holocene Greening Of The Afro-Asian Dust Belt Changed Sources Of Mineral Dust In West Asia, A Sharifi, Ln Murphy, A Pourmand, Ac Clement, Elizabeth A. Canuel
Early-Holocene Greening Of The Afro-Asian Dust Belt Changed Sources Of Mineral Dust In West Asia, A Sharifi, Ln Murphy, A Pourmand, Ac Clement, Elizabeth A. Canuel
VIMS Articles
Production, transport and deposition of mineral dust have significant impacts on different components of the Earth systems through time and space. In modern times, dust plumes are associated with their source region(s) using satellite and land -based measurements and trajectory analysis of air masses through time. Reconstruction of past changes in the sources of mineral dust as related to changes in climate, however, must rely on the knowledge of the geochemical and mineralogical composition of modern and paleodust, and that of their potential source origins. In this contribution, we present a 13,000-yr record of variations in radiogenic Sr-Nd-Hf isotopes and …
Millennial Soil Retention Of Terrestrial Organic Matter Deposited In The Bengal Fan, Kl French, Christopher J. Hein, N Haghipour, L Wacker, Hr Kudrass
Millennial Soil Retention Of Terrestrial Organic Matter Deposited In The Bengal Fan, Kl French, Christopher J. Hein, N Haghipour, L Wacker, Hr Kudrass
VIMS Articles
The abundance of organic carbon (OC) in vegetation and soils (similar to 2,600 PgC) compared to carbon in the atmosphere (similar to 830 PgC) highlights the importance of terrestrial OC in global carbon budgets. The residence time of OC in continental reservoirs, which sets the rates of carbon exchange between land and atmosphere, represents a key uncertainty in global carbon cycle dynamics. Retention of terrestrial OC can also distort bulk OC- and biomarker-based paleorecords, yet continental storage timescales remain poorly quantified. Using "bomb" radiocarbon (C-14) from thermonuclear weapons testing as a tracer, we model leaf-wax fatty acid and bulk OC …
Predicting Marsh Vulnerability To Sea-Level Rise Using Holocene Relative Sea-Level Data, Bp Horton, I Shennan, Sl Bradley, N Cahill, Matthew L. Kirwan, Re Kopp, Ta Shaw
Predicting Marsh Vulnerability To Sea-Level Rise Using Holocene Relative Sea-Level Data, Bp Horton, I Shennan, Sl Bradley, N Cahill, Matthew L. Kirwan, Re Kopp, Ta Shaw
VIMS Articles
Tidal marshes rank among Earth's vulnerable ecosystems, which will retreat if future rates of relative sea-level rise (RSLR) exceed marshes' ability to accrete vertically. Here, we assess the limits to marsh vulnerability by analyzing >780 Holocene reconstructions of tidal marsh evolution in Great Britain. These reconstructions include both transgressive (tidal marsh retreat) and regressive (tidal marsh expansion) contacts. The probability of a marsh retreat was conditional upon Holocene rates of RSLR, which varied between -7.7 and 15.2 mm/yr. Holocene records indicate that marshes are nine times more likely to retreat than expand when RSLR rates are >= 7.1 mm/yr. Coupling …
Numerical Model Of Geochronological Tracers For Deposition And Reworking Applied To The Mississippi Subaqueous Delta, Jj Birchler, Courtney K. Harris, Ta Kniskern, Cr Sherwood
Numerical Model Of Geochronological Tracers For Deposition And Reworking Applied To The Mississippi Subaqueous Delta, Jj Birchler, Courtney K. Harris, Ta Kniskern, Cr Sherwood
VIMS Articles
Measurements of naturally occurring, short-lived radioisotopes from sediment cores on the Mississippi subaqueous delta have been used to infer event bed characteristics such as depositional thicknesses and accumulation rates. Specifically, the presence of Beryllium-7 (Be-7) indicates recent riverine-derived terrestrial sediment deposition; while Thorium-234 (Th-234) provides evidence of recent suspension in marine waters. Sediment transport models typically represent coastal flood and storm deposition via estimated grain size patterns and deposit thicknesses, however, and do not directly calculate radioisotope activities and profiles, which leads to a disconnect between the numerical model and field observations. Here, observed radioisotopic profiles from the Mississippi subaqueous …
Cross-Scale Baroclinic Simulation Of The Effect Of Channel Dredging In An Estuarine Setting, Fei Ye, Harry V. Wang, H Huang, Zg Wang, Z Liu, X Li
Cross-Scale Baroclinic Simulation Of The Effect Of Channel Dredging In An Estuarine Setting, Fei Ye, Harry V. Wang, H Huang, Zg Wang, Z Liu, X Li
VIMS Articles
Holistic simulation approaches are often required to assess human impacts on a river-estuary-coastal system, due to the intrinsically linked processes of contrasting spatial scales. In this paper, a Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM) is applied in quantifying the impact of a proposed hydraulic engineering project on the estuarine hydrodynamics. The project involves channel dredging and land expansion that traverse several spatial scales on an ocean-estuary-river-tributary axis. SCHISM is suitable for this undertaking due to its flexible horizontal and vertical grid design and, more importantly, its efficient high-order implicit schemes applied in both the momentum and transport calculations. These …
Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof
Discerning Autotrophy, Mixotrophy And Heterotrophyin Marine Tack Archaea From The North Atlantic, L M. Seyler, L. R. Mcguinness, J. A. Gilbert, J. F. Biddle, Donglai Gong, L. J. Kerkhof
VIMS Articles
DNA stable isotope probing (SIP) was used to track the uptake of organic and inorganic carbon sources for TACK archaea(Thaumarchaeota/Aigarchaeota/Crenarchaeota/Korarchaeota) on a cruise of opportunity in the North Atlantic. Due to water limitations, duplicate samples from the deep photic (60–115 m), the mesopelagic zones (local oxygen minimum; 215–835 m)and the bathypelagic zone (2085–2835 m) were amended with various combinations of12C- or13C-acetate/urea/bicarbonate to assess cellular carbon acquisition. The SIP results indicated the majority of TACK archaeal operational taxonomic units(OTUs) incorporated13C from acetate and/or urea into newly synthesized DNA within 48 h. A small fraction (16%) of the OTUs, often representing the …
Massive Upland To Wetland Conversion Compensated For Historical Marsh Loss In Chesapeake Bay, Usa, Nathalie W. Schieder, David C. Walters, Matthew L. Kirwan
Massive Upland To Wetland Conversion Compensated For Historical Marsh Loss In Chesapeake Bay, Usa, Nathalie W. Schieder, David C. Walters, Matthew L. Kirwan
VIMS Articles
Sea level rise leads to coastal transgression, and the survival of ecosystems depends on their ability to migrate inland faster than they erode and submerge. We compared marsh extent between nineteenth-century maps and modern aerial photographs across the Chesapeake Bay, the largest estuary in North America, and found that Chesapeake marshes have maintained their spatial extent despite relative sea level rise rates that are among the fastest in the world. In the mapped region (i.e., 25% of modern Chesapeake Bay marshland),94 km2of marsh was lost primarily to shoreline erosion,whereas 101 km2of marsh was created by upland drowning.Simple projections over the …