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Articles 9271 - 9300 of 14014

Full-Text Articles in Oceanography and Atmospheric Sciences and Meteorology

Implementing Deep Drainage To Reduce Salinity In The Date Creek Catchment, South West Western Australia, Derk Bakker, John P. Collins, Justin Hardy Jan 2010

Implementing Deep Drainage To Reduce Salinity In The Date Creek Catchment, South West Western Australia, Derk Bakker, John P. Collins, Justin Hardy

Resource management technical reports

No abstract provided.


Combined Effects Of Heat Waves And Droughts On Avian Communities Across The Conterminous United States, Thomas P. Albright, Anna M. Pidgeon, Chadwick D. Rittenhouse, Murray K. Clayton, Brian D. Wardlow, Curtis H. Flather, Patrick D. Culbert, Volker C. Radeloff Jan 2010

Combined Effects Of Heat Waves And Droughts On Avian Communities Across The Conterminous United States, Thomas P. Albright, Anna M. Pidgeon, Chadwick D. Rittenhouse, Murray K. Clayton, Brian D. Wardlow, Curtis H. Flather, Patrick D. Culbert, Volker C. Radeloff

National Drought Mitigation Center: Faculty Publications

Increasing surface temperatures and climatic variability associated with global climate change are expected to produce more frequent and intense heat waves and droughts in many parts of the world. Our goal was to elucidate the fundamental, but poorly understood, effects of these extreme weather events on avian communities across the conterminous United States. Specifically, we explored: (1) the effects of timing and duration of heat and drought events, (2) the effects of jointly occurring drought and heat waves relative to these events occurring in isolation, and (3) how effects vary among functional groups related to nest location and migratory habit, …


Effects Of Lightning And Other Meteorological Factors On Fire Activity In The North American Boreal Forest: Implications For Fire Weather Forecasting, David Peterson, Jun Wang, Charles Ichoku, Lorraine Remer Jan 2010

Effects Of Lightning And Other Meteorological Factors On Fire Activity In The North American Boreal Forest: Implications For Fire Weather Forecasting, David Peterson, Jun Wang, Charles Ichoku, Lorraine Remer

Department of Earth and Atmospheric Sciences: Faculty Publications

The effects of lightning and other meteorological factors on wildfire activity in the North American boreal forest are statistically analyzed during the fire seasons of 2000–2006 through an integration of the following data sets: the MODerate Resolution Imaging Spectroradiometer (MODIS) level 2 fire products, the 3-hourly 32-km gridded meteorological data from North American Regional Reanalysis (NARR), and the lightning data collected by the Canadian Lightning Detection Network (CLDN) and the Alaska Lightning Detection Network (ALDN). Positive anomalies of the 500 hPa geopotential height field, convective available potential energy (CAPE), number of cloud-to-ground lightning strikes, and the number of consecutive dry …


Geological Analysis And Hydrodynamic Modeling Of Tropical Cyclone Influence: Northeastern Gulf Of Mexico Inner Shelf, Amy Lynn Spaziani Jan 2010

Geological Analysis And Hydrodynamic Modeling Of Tropical Cyclone Influence: Northeastern Gulf Of Mexico Inner Shelf, Amy Lynn Spaziani

LSU Master's Theses

The need to characterize offshore resources as borrow areas for beach restoration has initiated interest of the impact of storms to the inner continental shelf. While numerous studies have investigated the response of coastal systems to major storms, very little is known about the geological response of inner shelves to frequent and intense storms. This approach integrated a geological study with modeling of hydrodynamics during recent storms, in order to relate trends in the geological signature to physical forcing mechanisms during storms. First, waves and hydrodynamic conditions were modeled during two major recent storms that made landfall in the northeastern …


Consistency Of Projected Drought Over The Sahel With Changes In The Monsoon Circulation And Extremes In A Regional Climate Model Projections, M. B. Sylla, A. T. Gaye, G. S. Jenkins, Jeremy S. Pal, F. Giorgi Jan 2010

Consistency Of Projected Drought Over The Sahel With Changes In The Monsoon Circulation And Extremes In A Regional Climate Model Projections, M. B. Sylla, A. T. Gaye, G. S. Jenkins, Jeremy S. Pal, F. Giorgi

Civil and Environmental Engineering Faculty Works

As a step toward an increased understanding of climate change over West Africa, in this paper we analyze the relationship between rainfall changes and monsoon dynamics in high-resolution regional climate model experiments performed using the Regional Climate Model (RegCM3). Multidecadal simulations are carried out for present-day and future climate conditions under increased greenhouse gas forcing driven by the global climate model European Center/Hamburg 5 (ECHAM5). Compared to the present day, the future scenario simulation produces drier conditions over the Sahel and wetter conditions over orographic areas. The Sahel drying is accompanied by a weaker monsoon flow, a southward migration and …


Image Analysis For Water Surface & Subsurface Feature Detection In Shallow Waters, Charles R. Bostater Jr., James Jones, Heather Frystacky, Mate Kovacs, Oszkar Jozsa Jan 2010

Image Analysis For Water Surface & Subsurface Feature Detection In Shallow Waters, Charles R. Bostater Jr., James Jones, Heather Frystacky, Mate Kovacs, Oszkar Jozsa

Ocean Engineering and Marine Sciences Faculty Publications

Carefully collected airborne imagery demonstrates the ability to see water surface features as well as shallow bottom features such as submerged vegetation and manmade targets. Traditional photogrammetric imagery and airborne digital imagery both suffer from a loss in image clarity due to a number of factors, including capillary and small gravity waves, the water column or in-situ constituents. The use of submerged as well as surface man-made calibration targets deployed during airborne or in-situ subsurface image acquisitions forms a preliminary basis for correcting imagery in order to improve subsurface and surface features and their detection. Methods presented as well as …


Tsunami Hazard And Total Risk In The Caribbean Basin, X. William Proenza, George A. Maul Jan 2010

Tsunami Hazard And Total Risk In The Caribbean Basin, X. William Proenza, George A. Maul

Ocean Engineering and Marine Sciences Faculty Publications

Deadly western North Atlantic Ocean tsunami events in the last centuries have occurred along the east coast of Canada, the United States, most Caribbean islands, and the North Atlantic Coast of South America. The catastrophic Indian Ocean tsunami of 2004 reminded natural hazards managers that tsunami risk is endemic to all oceans. Total Risk is defined as hazard (frequency of tsunami events) times measures of elements at risk (human exposure) times measures of vulnerability (preparedness) in a given epoch (Nott, 2006). While the tsunami hazard in the Caribbean (averaging 19 ± 22 years between deadly events) is lower than Pacific …


Zebulon Pike: Great American Explorer Or Climate Spy?, Merlin P. Lawson, Randall Cerveny, Cary Mock Jan 2010

Zebulon Pike: Great American Explorer Or Climate Spy?, Merlin P. Lawson, Randall Cerveny, Cary Mock

Department of Earth and Atmospheric Sciences: Faculty Publications

Zebulon Pike is known in history books as one of America’s heroes—a great explorer whose adventures in the American West rivaled the Lewis and Clark Expedition and who became the namesake for Colorado’s Pike’s Peak. But what if the history books got it wrong, and Pike was actually not the hero everyone thinks he is? What if he was actually a spy carrying out a secret mission, or a scoundrel interested in overthrowing the American government and helping to carve a new empire out of the North American Southwest? Evidence from Pike’s famed expedition in 1806-1807 points to the possibility …


Evidence For Recent Population Bottlenecks In Northern Spotted Owls (Strix Occidentalis Caurina), W. Chris Funk, Eric D. Forsman, Matthew Johnson, Thomas D. Mullins, Susan M. Haig Jan 2010

Evidence For Recent Population Bottlenecks In Northern Spotted Owls (Strix Occidentalis Caurina), W. Chris Funk, Eric D. Forsman, Matthew Johnson, Thomas D. Mullins, Susan M. Haig

United States Geological Survey: Staff Publications

The northern spotted owl (Strix occidentalis caurina) is one of the most controversial threatened subspecies ever listed under the US Endangered Species Act. Despite protection of its remaining forest habitat, recent field studies show continued declines of northern spotted owls. One potential threat to northern spotted owls which has not yet been shown is loss of genetic variation from population bottlenecks. Bottlenecks can increase the probability of mating among related individuals, potentially causing inbreeding depression, and can decrease adaptive potential. Here we report evidence for recent bottlenecks in northern spotted owls using a large genetic dataset (352 individuals …


Subspecies Status And Population Genetic Structure In Piping Plover (Charadrius Melodus), Mark P. Miller, Susan M. Haig, Cheri L. Gratto-Trevor, Thomas D. Mullins Jan 2010

Subspecies Status And Population Genetic Structure In Piping Plover (Charadrius Melodus), Mark P. Miller, Susan M. Haig, Cheri L. Gratto-Trevor, Thomas D. Mullins

United States Geological Survey: Staff Publications

Piping Plover (Charadrius melodus) is a migratory shorebird that is listed as endangered in Canada and the U.S. Great Lakes and as threatened throughout the rest of its breeding and winter range. We undertook a comprehensive molecular-genetic investigation to (1) address subspecific taxonomy, (2) characterize population genetic structure, and (3) infer past bottlenecks and demographic processes in this species. Analyses included individuals from 23 U.S. states and Canadian provinces and were based on mitochondrial DNA sequences (580 base pairs, n = 245) and 8 nuclear microsatellite loci (n = 229). Our findings provide support for separate Atlantic and …


The Cleaning Of Burned And Contaminated Archaeological Maize Prior To 87sr/86sr Analysis, L.V. Benson, H. E. Taylor, T. I. Plowman, D. A. Roth, R. C. Antweiler Jan 2010

The Cleaning Of Burned And Contaminated Archaeological Maize Prior To 87sr/86sr Analysis, L.V. Benson, H. E. Taylor, T. I. Plowman, D. A. Roth, R. C. Antweiler

United States Geological Survey: Staff Publications

Accurate trace-metal and strontium-isotope analyses of archaeological corn cobs require that metal contaminants be removed prior to chemical analysis. Archaeological cobs are often coated with construction debris, dust, or soilwhich contains mineral particles. In addition, most archaeological cobs are partially or completely burned and the burned parts incorporate mineral debris in their hardened residual structures. Unburned cobs are weak ion exchangers and most metals within a cob are not firmly bound to cob organic matter; therefore, immersing cobs in acids and rinsing them in deionized water to remove mineral contaminants may result in the undesirable loss of metals, including strontium, …


Tree-Ring Dates And Demographic Change In The Southern Colorado Plateau And Rio Grande Regions, Michael S. Berry, Larry Benson Jan 2010

Tree-Ring Dates And Demographic Change In The Southern Colorado Plateau And Rio Grande Regions, Michael S. Berry, Larry Benson

United States Geological Survey: Staff Publications

In this chapter, tree-ring dates from the southern Colorado Plateau, Mogollon Highlands, and Rio Grande areas (fig. 3-1) (hereafter referred to as the study area) are used to estimate regional-scale timber-harvesting and construction activities between AD 600 and 1600 (the Basketmaker III through Pueblo IV periods). Within that time span, we focus our attention particularly on the AD 1045-1300 period, a time when anomalously wet periods alternated with megadroughts (fig. 3.2). Treering- date distributions (histograms) for eight archaeological subregions within the study area have been created using a database of more than twenty-four thousand tree-ring dates from archaeological sites. These …


Barcoding Bushmeat: Molecular Identification Of Central African And South American Harvested Vertebrates, Mitchell J. Eaton, Greta J. Meyers, Sergios-Orestis Kolokotronis, Matthew S. Leslie, Andrew P. Martin, George Amato Jan 2010

Barcoding Bushmeat: Molecular Identification Of Central African And South American Harvested Vertebrates, Mitchell J. Eaton, Greta J. Meyers, Sergios-Orestis Kolokotronis, Matthew S. Leslie, Andrew P. Martin, George Amato

United States Geological Survey: Staff Publications

The creation and use of a globally available database of DNA sequences from a standardized gene region has been proposed as a tool for species identification, assessing genetic diversity and monitoring the legal and illegal trade in wildlife species. Here, we contribute to the Barcode of Life Data System and test whether a short region of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene would reliably distinguish among a suite of commonly hunted African and South American mammal and reptile species. We used universal primers to generate reference barcode sequences of 645 bp for 23 species from five vertebrate …


Barcoding Bushmeat: Molecular Identification Of Central African And South American Harvested Vertebrates, Mitchell J. Eaton, Greta L. Meyers, Sergios-Orestis Kolokotronis, Matthew S. Leslie, Andrew P. Martin, George Amato Jan 2010

Barcoding Bushmeat: Molecular Identification Of Central African And South American Harvested Vertebrates, Mitchell J. Eaton, Greta L. Meyers, Sergios-Orestis Kolokotronis, Matthew S. Leslie, Andrew P. Martin, George Amato

United States Geological Survey: Staff Publications

The creation and use of a globally available database of DNA sequences from a standardized gene region has been proposed as a tool for species identification, assessing genetic diversity and monitoring the legal and illegal trade in wildlife species. Here, we contribute to the Barcode of Life Data System and test whether a short region of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene would reliably distinguish among a suite of commonly hunted African and South American mammal and reptile species. We used universal primers to generate reference barcode sequences of 645 bp for 23 species from five vertebrate …


The Role Of African Dust In The Formation Of Quaternary Soils On Mallorca, Spain And Implications For The Genesis Of Red Mediterranean Soils, Daniel R. Muhs, James Budahn, Anna Avila, Gary Skipp, Joshua Freeman, Deanna Patterson Jan 2010

The Role Of African Dust In The Formation Of Quaternary Soils On Mallorca, Spain And Implications For The Genesis Of Red Mediterranean Soils, Daniel R. Muhs, James Budahn, Anna Avila, Gary Skipp, Joshua Freeman, Deanna Patterson

United States Geological Survey: Staff Publications

African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These …


Assessing The Potential For Luminescence Dating Of Basalts, S. Tsukamoto, G. A.T. Duller, A. G. Wintle, Daniel R. Muhs Jan 2010

Assessing The Potential For Luminescence Dating Of Basalts, S. Tsukamoto, G. A.T. Duller, A. G. Wintle, Daniel R. Muhs

United States Geological Survey: Staff Publications

The possibility of dating basalt using luminescence was tested on four samples with independent age control from Cima volcanic !eld, California, with the ultimate aim of assessing whether the technique could be used to date sediments on the surface of Mars. Previous analysis of these samples had demonstrated that the infrared stimulated luminescence (IRSL) signal is most suitable for dating as it showed the lowest fading rate among various luminescence signals. In this study, changes in equivalent dose as a function of preheat are described. The ages for the two youngest Cima samples agree with the independent ages based on …


Littoral Cells, Longshore Transport And Wave Climate: An Examination Of Littoral Transport Along The Western Shore Of Prince Edward County, Ontario, Jayson A. Childs Jan 2010

Littoral Cells, Longshore Transport And Wave Climate: An Examination Of Littoral Transport Along The Western Shore Of Prince Edward County, Ontario, Jayson A. Childs

Theses and Dissertations (Comprehensive)

This study discusses the wave climate and potential littoral transport along the western shore of Prince Edward County approximately two hours east of Toronto along the northern shoreline of Lake Ontario. The limestone headlands and barrier bars of the western coast are exposed toward a southwesterly fetch of approximately 200 km that can produce large offshore wave heights of 2–5 m. The wave model STWAVE was used to transform a standard set of wave conditions developed from recent hindcast data to examine fair weather, storm and extreme conditions for five directions between south and west-northwest along the shore. The resulting …


Ancient Dna Analyses Exclude Humans As The Driving Force Behind Late Pleistocene Musk Ox (Ovibos Moschatus) Population Dynamics, Paula F. Campos, Eske Willerslev, Andrei Sher, Ludovic Orlando, Erik Axelsson, Alexei Tikhonov, Kim Aaris-Sorensen, Alex D. Greenwood, Ralf-Dietrich Kahlke, Pavel Kosintsev Jan 2010

Ancient Dna Analyses Exclude Humans As The Driving Force Behind Late Pleistocene Musk Ox (Ovibos Moschatus) Population Dynamics, Paula F. Campos, Eske Willerslev, Andrei Sher, Ludovic Orlando, Erik Axelsson, Alexei Tikhonov, Kim Aaris-Sorensen, Alex D. Greenwood, Ralf-Dietrich Kahlke, Pavel Kosintsev

Biological Sciences Faculty Publications

The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, or a combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived to the present. The musk ox has an intermediate story: relatively abundant during the Pleistocene, it is now restricted to Greenland and the Arctic Archipelago. In this study, we use ancient DNA sequences, temporally unbiased summary statistics, and Bayesian analytical techniques to infer musk ox population dynamics throughout the late Pleistocene and Holocene. Our results reveal …


Lsuhsc Facilities Biweekly Update: January 2010, Lsuhsc Property And Facilities Management Jan 2010

Lsuhsc Facilities Biweekly Update: January 2010, Lsuhsc Property And Facilities Management

LSUHSC Facilities Biweekly Updates: 2010

LSUHSC Facilities Biweekly Updates from January 15 and 29, 2010.

These updates describe damage and a timeline of repairs at the LSU Health Sciences Center - New Orleans campus due to Hurricane Katrina which made landfall August 29, 2005.


Lsuhsc Facilities Daily Update: January 2010, Lsuhsc Property And Facilities Management Jan 2010

Lsuhsc Facilities Daily Update: January 2010, Lsuhsc Property And Facilities Management

LSUHSC Facilities Daily Updates: 2010

LSUHSC Facilities Daily Updates from January 2010.

These updates describe damage and a timeline of repairs at the LSU Health Sciences Center - New Orleans campus due to Hurricane Katrina which made landfall August 29, 2005.


The Composition Of Precipitation In El Paso, Texas, Sonny P. Emmert Jan 2010

The Composition Of Precipitation In El Paso, Texas, Sonny P. Emmert

Open Access Theses & Dissertations

The composition of precipitation reflects the transport of particles from varying air mass source regions as well as input from local environmental and anthropogenic activities. Air research in El Paso, TX, U.S.A/Ciudad Juarez, Chihuahua, Mexico has been traditionally limited to studies of local inputs of air pollution; no transition has been made to studying the scavenging, washout, and transport of pollutants by precipitation. The goal of this research project was to identify transported pollutants in precipitation, and determine if there were any health and ecological implications. The research investigated biological, chemical, and geological constituents in precipitation samples collected between September …


Marine Benthic Habitat Mapping Of Muir Inlet, Glacier Bay National Park And Preserve, Alaska With An Evaluation Of The Coastal And Marine Ecological Classification Standard Iii, Luke D. Mitchell, Guy R. Cochrane, Lisa Etherington, Ross D. Powell, Larry A. Mayer Jan 2010

Marine Benthic Habitat Mapping Of Muir Inlet, Glacier Bay National Park And Preserve, Alaska With An Evaluation Of The Coastal And Marine Ecological Classification Standard Iii, Luke D. Mitchell, Guy R. Cochrane, Lisa Etherington, Ross D. Powell, Larry A. Mayer

Center for Coastal and Ocean Mapping

Seafloor geology and potential benthic habitats were mapped in Muir Inlet, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, ground-truth information, and geological interpretations. Muir Inlet is a recently deglaciated fjord that is under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the Coastal and Marine Ecological Classification Standard (CMECS) recently developed by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Substrates within Muir Inlet …


Participatory Planning For A Promised Land: Citizen-Led, Comprehensive Land Use Planning In New York’S Adirondack Park, Ann Hope Ruzow Holland Jan 2010

Participatory Planning For A Promised Land: Citizen-Led, Comprehensive Land Use Planning In New York’S Adirondack Park, Ann Hope Ruzow Holland

Antioch University Dissertations & Theses

New York’s Adirondack Park is internationally recognized for its biological diversity. Greater in size than Yellowstone, Everglades, Glacier, and Grand Canyon National Park combined, the Adirondacks are the largest protected area within the Northern Appalachian/Acadian Eco-Region and within the contiguous United States. Ecologists, residents of the Park, and others are concerned about rapid land use change occurring within the borders of the Park. Almost half of the six million acres encompassed by the Park boundary is privately-owned, where 80% of land use decisions fall within the jurisdiction of local governments. The comprehensive planning process of one such local government, the …


Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige Jan 2010

Benthic Ecology From Space: Optics And Net Primary Production In Seagrass And Benthic Algae Across The Great Bahama Bank, Heidi M. Dierssen, Richard C. Zimmerman, Lisa A. Drake, David J. Burdige

OES Faculty Publications

Development of repeatable and quantitative tools are necessary for determining the abundance and distribution of different types of benthic habitats, detecting changes to these ecosystems, and determining their role in the global carbon cycle. Here we used ocean color remote sensing techniques to map different major groups of primary producers and estimate net primary productivity (NPP) across Great Bahama Bank (GBB). Field investigations on the northern portion of the GBB in 2004 revealed 3 dominant types of benthic primary producers: seagrass, benthic macroalgae, and microalgae attached to sediment. Laboratory measurements of NPP ranged from barely net autotrophic for grapestone sediment …


A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio Jan 2010

A Seasonal Study Of Dissolved Cobalt In The Ross Sea, Antarctica: Micronutrient Behavior, Absence Of Scavenging, And Relationships With Zd, Cd, And P., M. A. Saito, T. J. Goepfert, A. E. Noble, E. M. Bertrand, Peter N. Sedwick, Giacomo R. Ditullio

OES Faculty Publications

We report the distribution of cobalt (Co) in the Ross Sea polynya during austral summer 2005-2006 and the following austral spring 2006. The vertical distribution of total dissolved Co (dCo) was similar to soluble reactive phosphate (PO(4)(3-)), with dCo and PO(4)(3-) showing a significant correlation throughout the water column (r(2) = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from similar to ~ 45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range …


Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan Jan 2010

Determination Of Total Dissolved Cobalt In Uv-Irradiated Seawater Using Flow Injection With Chemiluminescence Detection, Rachel U. Shelley, Bernhard Zachhuber, Peter N. Sedwick, Paul J. Worsfold, Maeve C. Lohan

OES Faculty Publications

A sensitive flow-injection method with chemiluminescence detection (FI-CL) for the determination of dissolved cobalt in open ocean samples, suitable for shipboard use has been developed. To date, FI methods for dissolved cobalt have been used only in coastal and estuarine waters. Therefore, significant modifications to existing methods were required, including (1) the use of a commercially available iminodiacetate (IDA) resin (Toyopearl AF-chelate 650M) in place of resin immobilized 8-hydroxyquinoline for online preconcentration and matrix removal, (2) the introduction of acidified ammonium acetate (pH 4) as a column-conditioning step before sample loading and rinse steps, and most importantly, (3) UV irradiation …


On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church Jan 2010

On The Fractional Solubillity Of Copper In Marine Aerosols: Toxicity Of Aeolian Copper Revisited, Edward R. Sholkovitz, Peter N. Sedwick, Thomas M. Church

OES Faculty Publications

Paytan et al. (2009) argue that the atmospheric deposition of aerosols lead to copper concentrations that are potentially toxic to marine phytoplankton in a large area of tropical and subtropical North Atlantic Ocean. A key assumption in their model is that all marine aerosols (mineral dust and anthropogenic particles) have a high (40%) fractional solubility of copper. Our data show that the fractional solubility of copper for Saharan dust over the Sargasso Sea and Bermuda is significantly lower (1-7%). In contrast, anthropogenic aerosols with non-Saharan sources have significantly higher values (10-100%). Hence, the potential Cu toxicity in the tropical and …


Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully Jan 2010

Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully

OES Faculty Publications

Turbulent mixing of salt is examined in a shallow salt wedge estuary with strong fluvial and tidal forcing. A numerical model of the Merrimack River estuary is used to quantify turbulent stress, shear production, and buoyancy flux. Little mixing occurs during flood tides despite strong velocities because bottom boundary layer turbulence is dislocated from stratification elevated in the water column. During ebbs, bottom salinity fronts form at a series of bathymetric transitions. At the fronts, near-bottom velocity and shear stress are low, but shear, stress, and buoyancy flux are elevated at the pycnocline. Internal shear layers provide the dominant source …


Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman Jan 2010

Modeling The Vertical Distributions Of Downwelling Plane Irradiance And Diffuse Attenuation Coefficient In Optically Deep Waters, X. J. Pan, Richard C. Zimmerman

OES Faculty Publications

The diffuse attenuation coefficient Kᵈ is critical to understand the vertical distribution of underwater downwelling irradiance (Eᵈ). Theoretically Eᵈ is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kᵈ is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Eᵈ(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4%. Field …


The Widespread Occurrence Of Coupled Carbonate Dissolution/Reprecipitation In Surface Sediments On The Bahamas Bank, David J. Burdige, Xinping Hu, Richard C. Zimmerman Jan 2010

The Widespread Occurrence Of Coupled Carbonate Dissolution/Reprecipitation In Surface Sediments On The Bahamas Bank, David J. Burdige, Xinping Hu, Richard C. Zimmerman

OES Faculty Publications

Using two complimentary approaches (pore water advection/diffusion/reaction modeling and stable isotope mass balance calculations) we show that carbonate dissolution/reprecipitation occurs on early diagenetic time scales across a broad range of sediments on the Great Bahamas Bank. The input of oxygen into the sediments, which strongly controls sediment carbonate dissolution, has two major sources belowground input by seagrasses (that is, seagrass O2 pumping), and permeability-driven advective pore water exchange. The relative importance of these O2 delivery mechanisms depends on both seagrass density, and on how bottom water flow interacts with the seagrass canopy and leads to this advective exchange. …