Meteoroid mayhem in Ole Virginny: Source of the North American tektite strewn field

USGS Publications Warehouse

Poag, C. Wylie; Powars, David S.; Poppe, Lawrence J.; Mixon, Robert B.

1994-01-01

New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peakring crater in southern Germany. We speculate that the Chesapeake Bay crater is the source of the North American tektite strewn field.

Meteoroid mayhem in Ole Virginny: source of the North American tektite strewn field

USGS Publications Warehouse

Poag, C.W.; Powars, D.S.; Poppe, L.J.; Mixon, R.B.

1994-01-01

New seismic reflection data from Chesapeake Bay reveal a buried, 85-km-wide, 1.5-2.0-km-deep, peak-ring impact crater, carved through upper Eocene to Lower Cretaceous sedimentary strata and into underlying pre-Mesozoic crystalline basement rocks. A polymictic, late Eocene impact breccia, composed mainly of locally derived sedimentary debris (determined from four continuous cores), surrounds and partly fills the crater. Structural and sedimentary characteristics of the Chesapeake Bay crater closely resemble those of the Miocene Ries peak-ring crater in southern Germany. It is speculated that the Chesapeake Bay crater is the source of the North American tektite strewn field. -Authors

Holistic assessment of Chwaka Bay's multi-gear fishery - Using a trophic modeling approach

NASA Astrophysics Data System (ADS)

Rehren, Jennifer; Wolff, Matthias; Jiddawi, Narriman

2018-04-01

East African coastal communities highly depend on marine resources for not just income but also protein supply. The multi-species, multi-gear nature of East African fisheries makes this type of fishery particularly difficult to manage, as there is a trade-off between maximizing total catch from all gears and species and minimizing overfishing of target species and the disintegration of the ecosystem. The use and spatio-temporal overlap of multiple gears in Chwaka Bay (Zanzibar) has led to severe conflicts between fishermen. There is a general concern of overfishing in the bay because of the widespread use of small mesh sizes and destructive gears such as dragnets and spear guns. We constructed an Ecopath food web model to describe the current trophic flow structure and fishing pattern of the bay. Based on this model, we explored the impact of different gears on the ecosystem and the fishing community in order to give advice for gear based management in the bay. Results indicate that Chwaka bay is a productive, shallow water system, with biomass concentrations around the first and second trophic level. The system is greatly bottom-up driven and dominated by primary producers and invertebrates. The trophic and network indicators as well as the community energetics characterize Chwaka Bay as relatively mature. Traps and dragnets have the strongest impact on the ecosystem and on the catches obtained by other gears. Both gears potentially destabilize the ecosystem by reducing the biomass of top-down controlling key species (including important herbivores of macroalgae). The dragnet fishery is the least profitable, but provides most jobs for the fishing community. Thus, a complete ban of dragnets in the bay would require the provision of alternative livelihoods. Due to the low resource biomass of fish in the bay and the indication of a loss of structural control of certain fish groups, Chwaka Bay does not seem to provide scope for further expansion of the fishery. Instead, we recommend an effort control of traps and a reduction in the use of dragnets, partially by redistributing them to the more profitable and less impacting gears (e.g. longlines, gillnets, handlines).

Deep drilling in the Chesapeake Bay impact structure - An overview

USGS Publications Warehouse

Gohn, G.S.; Koeberl, C.; Miller, K.G.; Reimold, W.U.

2009-01-01

The late Eocene Chesapeake Bay impact structure lies buried at moderate depths below Chesapeake Bay and surrounding landmasses in southeastern Virginia, USA. Numerous characteristics made this impact structure an inviting target for scientific drilling, including the location of the impact on the Eocene continental shelf, its threelayer target structure, its large size (??85 km diameter), its status as the source of the North American tektite strewn field, its temporal association with other late Eocene terrestrial impacts, its documented effects on the regional groundwater system, and its previously unstudied effects on the deep microbial biosphere. The Chesapeake Bay Impact Structure Deep Drilling Project was designed to drill a deep, continuously cored test hole into the central part of the structure. A project workshop, funding proposals, and the acceptance of those proposals occurred during 2003-2005. Initial drilling funds were provided by the International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS). Supplementary funds were provided by the National Aeronautics and Space Administration (NASA) Science Mission Directorate, ICDP, and USGS. Field operations were conducted at Eyreville Farm, Northampton County, Virginia, by Drilling, Observation, and Sampling of the Earth's Continental Crust (DOSECC) and the project staff during September-December 2005, resulting in two continuously cored, deep holes. The USGS and Rutgers University cored a shallow hole to 140 m in April-May 2006 to complete the recovered section from land surface to 1766 m depth. The recovered section consists of 1322 m of crater materials and 444 m of overlying postimpact Eocene to Pleistocene sediments. The crater section consists of, from base to top: basement-derived blocks of crystalline rocks (215 m); a section of suevite, impact melt rock, lithic impact breccia, and cataclasites (154 m); a thin interval of quartz sand and lithic blocks (26 m); a granite megablock (275 m); and sediment blocks and boulders, polymict, sediment-clast-dominated sedimentary breccias, and a thin upper section of stratified sediments (652 m). The cored postimpact sediments provide insight into the effects of a large continental-margin impact on subsequent coastal-plain sedimentation. This volume contains the first results of multidisciplinary studies of the Eyreville cores and related topics. The volume is divided into these sections: geologic column; borehole geophysical studies; regional geophysical studies; crystalline rocks, impactites, and impact models; sedimentary breccias; postimpact sediments; hydrologic and geothermal studies; and microbiologic studies. ?? 2009 The Geological Society of America.

Seismic expression of the Chesapeake Bay impact crater: Structural and morphologic refinements based on new seismic data

USGS Publications Warehouse

Poag, C. Wylie; Hutchinson, Deborah R.; Colman, Steve M.; Lee, Myung W.; Dressler, B.O.; Sharpton, V.L.

1999-01-01

This work refines previous interpretations of the structure and morphology of the Chesapeake Bay impact crater on the basis of more than 1,200 km of multichannel and single-channel seismic reflection profiles collected in the bay and on the adjacent continental shelf. The outer rim, formed in sedimentary rocks, is irregularly circular, with an average diameter of ~85 km. A 20–25-km-wide annular trough separates the outer rim from an ovate, crystalline peak ring of ~200 m of maximum relief. The inner basin is 35–40 km in diameter, and at least 1.26 km deep. A crystalline(?) central peak, approximately 1 km high, is faintly imaged on three profiles, and also is indicated by a small positive Bouguer gravity anomaly. These features classify the crater as a complex peak-ring/central peak crater. Chesapeake Bay Crater is most comparable to the Ries and Popigai Craters on Earth; to protobasins on Mars, Mercury, and the Moon; and to type D craters on Venus.

Sediment bacterial community structures and their predicted functions implied the impacts from natural processes and anthropogenic activities in coastal area.

PubMed

Su, Zhiguo; Dai, Tianjiao; Tang, Yushi; Tao, Yile; Huang, Bei; Mu, Qinglin; Wen, Donghui

2018-06-01

Coastal ecosystem structures and functions are changing under natural and anthropogenic influences. In this study, surface sediment samples were collected from disturbed zone (DZ), near estuary zone (NEZ), and far estuary zone (FEZ) of Hangzhou Bay, one of the most seriously polluted bays in China. The bacterial community structures and predicted functions varied significantly in different zones. Firmicutes were found most abundantly in DZ, highlighting the impacts of anthropogenic activities. Sediment total phosphorus was most influential on the bacterial community structures. Predicted by PICRUSt analysis, DZ significantly exceeded FEZ and NEZ in the subcategory of Xenobiotics Biodegradation and Metabolism; and DZ enriched all the nitrate reduction related genes, except nrfA gene. Seawater salinity and inorganic nitrogen, respectively as the representative natural and anthropogenic factor, performed exact-oppositely in nitrogen metabolism functions. The changes of bacterial community compositions and predicted functions provide a new insight into human-induced pollution impacts on coastal ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

Postimpact deformation associated with the late Eocene Chesapeake Bay impact structure in southeastern Virginia

USGS Publications Warehouse

Johnson, G.H.; Kruse, S.E.; Vaughn, A.W.; Lucey, J.K.; Hobbs, C. H.; Powars, D.S.

1998-01-01

Upper Cenozoic strata covering the Chesapeake Bay impact structure in southeastern Virginia record intermittent differential movement around its buried rim. Miocene strata in a graben detected by seismic surveys on the York River exhibit variable thickness and are deformed above the creater rim. Fan-like interformational and intraformational angular unconformities within Pliocene-Pleistocene strata, which strike parallel to the crater rim and dip 2-3?? away from the crater center, indicate that deformation and deposition were synchronous. Concentric, large-scale crossbedded, bioclastics and bodies of Pliocene age within ~20km of the buried crater rim formed on offshore shoals, presumably as subsiding listric slump blocks rotated near the crater rim.

Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

USGS Publications Warehouse

Lee, S.R.; Horton, J. Wright; Walker, R.J.

2006-01-01

The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270?? higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events. ?? The Meteoritical Society, 2006.

Imaging 50,000 Oriented Ovoid Depressions Using LiDAR Elevation Data Elucidates the Enigmatic Character of The Carolina Bays: Wind & Wave, Or Cosmic Impact Detritus?

NASA Astrophysics Data System (ADS)

Davias, M. E.; Harris, T. H. S.

2017-12-01

80 years after aerial photography revealed thousands of aligned oval depressions on the USA's Atlantic Coastal Plain, the geomorphology of the "Carolina bays" remains enigmatic. Geologists and astronomers alike hold that invoking a cosmic impact for their genesis is indefensible. Rather, the bays are commonly attributed to gradualistic fluvial, marine and/or aeolian processes operating during the Pleistocene era. The major axis orientations of Carolina bays are noted for varying statistically by latitude, suggesting that, should there be any merit to a cosmic hypothesis, a highly accurate triangulation network and suborbital analysis would yield a locus and allow for identification of a putative impact site. Digital elevation maps using LiDAR technology offer the precision necessary to measure their exquisitely-carved circumferential rims and orientations reliably. To support a comprehensive geospatial survey of Carolina bay landforms (Survey) we generated about a million km2 of false-color hsv-shaded bare-earth topographic maps as KML-JPEG tile sets for visualization on virtual globes. Considering the evidence contained in the Survey, we maintain that interdisciplinary research into a possible cosmic origin should be encouraged. Consensus opinion does hold a cosmic impact accountable for an enigmatic Pleistocene event - the Australasian tektite strewn field - despite the failure of a 60-year search to locate the causal astroblem. Ironically, a cosmic link to the Carolina bays is considered soundly falsified by the identical lack of a causal impact structure. Our conjecture suggests both these events are coeval with a cosmic impact into the Great Lakes area during the Mid-Pleistocene Transition, at 786 ka ± 5 k. All Survey data and imagery produced for the Survey are available on the Internet to support independent research. A table of metrics for 50,000 bays examined for the Survey is available from an on-line Google Fusion Table: https://goo.gl/XTHKC4 . Each bay is also geospatially referenceable through a map containing clickable placemarks that provide information windows displaying that bay's measurements as well as further links which allows visualization of the associated LiDAR imagery and the bay's planform measurement overlay within the Google Earth virtual globe: https://goo.gl/EHR4Lf .

High-resolution seismic reflection/refraction images near the outer margin of the Chesapeake Bay impact crater, York-James Peninsula, southeastern Virginia

USGS Publications Warehouse

Catchings, R.D.; Saulter, D.E.; Powars, D.S.; Goldman, M.R.; Dingler, J.A.; Gohn, G.S.; Schindler, J.S.; Johnson, G.H.

2001-01-01

Powars and Bruce (1999) showed that the Chesapeake Bay region of southeastern Virginia was the site of an asteroid or comet impact during the late Eocene, approximately 35 million years ago (Fig. 1). Initial borehole and marine seismic-reflection data revealed a 90-km-diameter impact structure, referred to as the Chesapeake Bay Impact Crater (CBIC), that lies buried beneath the southern Chesapeake Bay and surrounding Virginia Coastal Plain (Powars and Bruce, Figs. 1b). Stratigraphic correlations among a series of boreholes suggest that the impact disrupted basement rock and the overlying Cretaceous through middle Eocene deltaic and marine sediments. The CBIC truncates important regional sedimentary aquifer systems and possibly caused differential flushing of connate seawater. Therefore, the CBIC affects the present-day ground-water quantity and quality in the rapidly growing Hampton Roads region of southeastern Virginia. Impact-generated faults in the basement rock may be the sources of small-to-moderate earthquakes that have been occurred around the perimeter of the impact structure over the past few hundred years (Johnson et al., 1998). Powars and Bruce (1999) suggest that 150 m to 490 m of relatively undisturbed, post-impact Coastal-Plain sediments overlie the impact-disrupted sediments and basement rocks west of Chesapeake Bay. Their interpretation of marine seismic data, released from Texaco and Exxon, revealed a central 38-km-wide, 1.6-km-deep disrupted zone in the basement rocks (inner basin), which is surrounded by a 21- to 31-km-wide, 1- km-deep annular trough. Steep rim escarpments surround these features, which they mapped regionally as the outer and inner margins (rims) of the CBIC (Fig. 1b). The outer margin is a slumped terrace zone that has a 120- to 305-m-high gullied escarpment and varies in width from 0.8 to 3.2 km. However, the geographic bounds of the CBIC, its effects on the regional aquifer systems, and the distribution of impact generated faults and fractures in basement are not well determined. To better determine some of the unknowns associated with the CBIC, we conducted a 350-m-long, high-resolution seismic reflection and refraction survey, referred to here as the CBIC-1 seismic survey, on the York-James Peninsula in June 1999. In particular, we attempted to: better define the outer margin of the CBIC, understand lateral variations in the stratigraphic sequence, help assess potential hazards associated with regional seismicity, and determine acquisition parameters needed for shallow-depth seismic imaging in the Chesapeake Bay area.

Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

USGS Publications Warehouse

Declercq, J.; Dypvik, H.; Aagaard, Per; Jahren, J.; Ferrell, R.E.; Horton, J. Wright

2009-01-01

The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

Chesapeake Bay impact structure: A blast from the past

USGS Publications Warehouse

Powars, David S.; Edwards, Lucy E.; Gohn, Gregory S.; Horton, J. Wright

2015-10-28

Since its discovery in the early 1990s, scientists have conducted deep drilling and geophysical surveys of the impact structure to find out more about its size, composition, structure, age, and biological effects and to understand its lingering influences on the regional groundwater system. These efforts culminated in the drilling of a 1-mile-deep, continuously sampled corehole in 2005 by an international group of scientists and agencies.

Gravity investigations of the Chesapeake Bay impact structure

USGS Publications Warehouse

Plescia, J.B.; Daniels, D.L.; Shah, A.K.

2009-01-01

The Chesapeake Bay impact structure is a complex impact crater, ??85 km in diameter, buried beneath postimpact sediments. Its main structural elements include a central uplift of crystalline bedrock, a surrounding inner crater filled with impact debris, and an annular faulted margin composed of block-faulted sediments. The gravity anomaly is consistent with that of a complex impact consisting of a central positive anomaly over the central uplift and an annular negative anomaly over the inner crater. An anomaly is not recognized as being associated with the faulted margin or the outer edge of the structure. Densities from the Eyreville drill core and modeling indicate a density contrast of ??0.3-0.6 g cm-3 between crystalline basement and the material that fills the inner crater (e.g., Exmore breccia and suevite). This density contrast is somewhat higher than for other impact structures, but it is a function of the manner in which the crater fill was deposited (as a marine resurge deposit). Modeling of the gravity data is consistent with a depth to basement of ??1600 m at the site of Eyreville drill hole and 800 m at the central uplift. Both depths are greater than the depth at which crystalline rocks were encountered in the cores, suggesting that the cored material is highly fractured para-allochthonous rock. ?? 2009 The Geological Society of America.

Impacts of Storm Surge Mitigation Strategies on Aboveground Storage Tank Chemical Spill Transport

NASA Astrophysics Data System (ADS)

Do, C.; Bass, B. J.; Bernier, C.; Samii, A.; Dawson, C.; Bedient, P. B.

2017-12-01

The Houston Ship Channel (HSC), located in the hurricane-prone Houston-Galveston region of the upper Texas Coast, is one of the busiest waterways in the United States and is home to one of the largest petrochemical complexes in the world. Due to the proximity of the HSC to Galveston Bay and the Gulf of Mexico, chemical spills resulting from storm surge damage to aboveground storage tanks (ASTs) pose serious threats to the environment, residential communities, and national/international markets whose activities in the HSC generate billions of dollars annually. In an effort to develop a comprehensive storm surge mitigation strategy for Galveston Bay and its constituents, Rice University's Severe Storm Prediction, Education, and Evacuation from Disasters Center proposed two structural storm surge mitigation concepts, the Mid Bay Structure (MBS) and the Lower Bay Structure (LBS) as components of the Houston-Galveston Area Protection System (H-GAPS) project. The MBS consists of levees along the HSC and a navigational gate across the channel, and the LBS consists of a navigation gate and environmental gates across Bolivar Road. The impacts of these two barrier systems on the fate of AST chemical spills in the HSC have previously been unknown. This study applies the coupled 2D SWAN+ADCIRC model to simulate hurricane storm surge circulation within the Gulf of Mexico and Galveston Bay due to a synthetic storm which results in approximately 250-year surge levels in Galveston Bay. The SWAN+ADCIRC model is run using high-resolution computational meshes that incorporate the MBS and LBS scenarios, separately. The resulting wind and water velocities are then fed into a Lagrangian particle transport model to simulate the spill trajectories of the ASTs most likely to fail during the 250-year proxy storm. Results from this study illustrate how each storm surge mitigation strategy impacts the transport of chemical spills (modeled as Lagrangian particles) during storm surge as compared to the base case with only currently existing mitigation features in place. This study is part of a larger effort to evaluate the costs and benefits of several storm surge mitigation configurations proposed by the H-GAPS project.

Gulf of Mexico Integrated Science - Tampa Bay Study: Watershed and Estuary Mapping

USGS Publications Warehouse

Hansen, Mark

2005-01-01

Tampa Bay, Florida, and its environs have experienced phenomenal urban growth and significant changes in land-use practices over the past 50 years. This trend is expected to continue, with human activity intensifying and affecting a wider geographic region. Urbanization creates impervious surfaces, which increase stormwater runoff and contribute to greater amounts of chemicals flowing into coastal waters. Man-made structures including bridges, a gas pipeline, desalination plant, ports, navigation channels, and extensive sea walls have been built and will continue to be maintained and modified. This task of the Tampa Bay Study aims to provide a better understanding of these and other man-made impacts on the Tampa Bay region.

Coring the Chesapeake Bay impact crater

USGS Publications Warehouse

Poag, C.W.

2004-01-01

In July 1983, the shipboard scientists of Deep Sea Drilling Project Leg 95 found an unexpected bonus in a core taken 150 kilometers east of Atlantic City, N.J. At Site 612, the scientists recovered a 10-centimeter-thick layer of late Eocene debris ejected from an impact about 36 million years ago. Microfossils and argon isotope ratios from the same layer reveal that the ejecta were part of a broad North American impact debris field, previously known primarily from the Gulf of Mexico and Caribbean Sea. Since that serendipitous beginning, years of seismic reflection profiling, gravity measurements and core drilling have confirmed the source of that strewn field - the Chesapeake Bay impact crater, the largest structure of its kind in the United States, and the sixth-largest impact crater on Earth.

Polar organic compounds in pore waters of the Chesapeake Bay impact structure, Eyreville core hole: Character of the dissolved organic carbon and comparison with drilling fluids

USGS Publications Warehouse

Rostad, C.E.; Sanford, W.E.

2009-01-01

Pore waters from the Chesapeake Bay impact structure cores recovered at Eyreville Farm, Northampton County, Virginia, were analyzed to characterize the dissolved organic carbon. After squeezing or centrifuging, a small volume of pore water, 100 ??L, was taken for analysis by electrospray ionization-mass spectrometry. Porewater samples were analyzed directly without filtration or fractionation, in positive and negative mode, for polar organic compounds. Spectra in both modes were dominated by low-molecular-weight ions. Negative mode had clusters of ions differing by -60 daltons, possibly due to increasing concentrations of inorganic salts. The numberaverage molecular weight and weight-average molecular weight values for the pore waters from the Chesapeake Bay impact structure are higher than those reported for other aquatic sources of natural dissolved organic carbon as determined by electrospray ionization-mass spectrometry. In order to address the question of whether drilling mud fluids may have contaminated the pore waters during sample collection, spectra from the pore waters were compared to spectra from drilling mud fluids. Ions indicative of drilling mud fluids were not found in spectra from the pore waters, indicating there was no detectable contamination, and highlighting the usefulness of this analytical technique for detecting potential contamination during sample collection. ?? 2009 The Geological Society of America.

Macrobenthic community structure in the northern Saudi waters of the Gulf, 14 years after the 1991 oil spill.

PubMed

Joydas, T V; Qurban, Mohammad A; Al-Suwailem, Abdulaziz; Krishnakumar, P K; Nazeer, Zahid; Cali, N A

2012-02-01

The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15 years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14 years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluating confidence in the impact of regulatory nutrient reduction and assessing the competing impact of climate change

NASA Astrophysics Data System (ADS)

Irby, I.; Friedrichs, M. A. M.

2017-12-01

Human impacts on the Chesapeake Bay through increased nutrient run-off as a result of land-use change, urbanization, and industrialization, have resulted in a degradation of water quality over the last half-century. These direct impacts, compounded with human-induced climate changes such as warming, rising sea level, and changes in precipitation, have elevated the conversation surrounding the future of the Bay's water quality. As a result, in 2010, a Total Maximum Daily Load (TMDL) was established for the Chesapeake Bay that limited nutrient and sediment input in an effort to increase dissolved oxygen. This research utilizes a multiple model approach to evaluate confidence in the estuarine water quality modeling portion of the TMDL. One of the models is then used to assess the potential impact climate change may have on the success of currently mandated nutrient reduction levels in 2050. Results demonstrate that although the models examined differ structurally and in biogeochemical complexity, they project a similar attainment of regulatory water quality standards after nutrient reduction, while also establishing that meeting water quality standards is relatively independent of hydrologic conditions. By developing a Confidence Index, this research identifies the locations and causes of greatest uncertainty in modeled projections of water quality. Although there are specific locations and times where the models disagree, this research lends an increased degree of confidence in the appropriateness of the TMDL levels and in the general impact nutrient reductions will have on Chesapeake Bay water quality under current environmental conditions. However, when examining the potential impacts of climate change, this research shows that the combined impacts of increasing temperature, sea level, and river flow negatively affect dissolved oxygen throughout the Chesapeake Bay and impact progress towards meeting the water quality standards associated with the TMDL with increased temperature as the primary culprit. These results, having been continually shared with the regulatory TMDL modelers, will aid in the decision making for the 2017 TMDL Mid-Point Assessment.

Linking Structural Equation Modelling with Bayesian Network and Coastal Phytoplankton Dynamics in Bohai Bay

NASA Astrophysics Data System (ADS)

Chu, Jiangtao; Yang, Yue

2018-06-01

Bayesian networks (BN) have many advantages over other methods in ecological modelling and have become an increasingly popular modelling tool. However, BN are flawed in regard to building models based on inadequate existing knowledge. To overcome this limitation, we propose a new method that links BN with structural equation modelling (SEM). In this method, SEM is used to improve the model structure for BN. This method was used to simulate coastal phytoplankton dynamics in Bohai Bay. We demonstrate that this hybrid approach minimizes the need for expert elicitation, generates more reasonable structures for BN models and increases the BN model's accuracy and reliability. These results suggest that the inclusion of SEM for testing and verifying the theoretical structure during the initial construction stage improves the effectiveness of BN models, especially for complex eco-environment systems. The results also demonstrate that in Bohai Bay, while phytoplankton biomass has the greatest influence on phytoplankton dynamics, the impact of nutrients on phytoplankton dynamics is larger than the influence of the physical environment in summer. Furthermore, despite the Redfield ratio indicating that phosphorus should be the primary nutrient limiting factor, our results indicate that silicate plays the most important role in regulating phytoplankton dynamics in Bohai Bay.

Monoclinic tridymite in clast-rich impact melt rock from the Chesapeake Bay impact structure

USGS Publications Warehouse

Jackson, John C.; Horton, J. Wright; Chou, I-Ming; Belkin, Harvey E.

2011-01-01

X-ray diffraction and Raman spectroscopy confirm a rare terrestrial occurrence of monoclinic tridymite in clast-rich impact melt rock from the Eyreville B drill core in the Chesapeake Bay impact structure. The monoclinic tridymite occurs with quartz paramorphs after tridymite and K-feldspar in a microcrystalline groundmass of devitrified glass and Fe-rich smectite. Electron-microprobe analyses revealed that the tridymite and quartz paramorphs after tridymite contain different amounts of chemical impurities. Inspection by SEM showed that the tridymite crystal surfaces are smooth, whereas the quartz paramorphs contain irregular tabular voids. These voids may represent microporosity formed by volume decrease in the presence of fluid during transformation from tridymite to quartz, or skeletal growth in the original tridymite. Cristobalite locally rims spherulites within the same drill core interval. The occurrences of tridymite and cristobalite appear to be restricted to the thickest clast-rich impact melt body in the core at 1402.02–1407.49 m depth. Their formation and preservation in an alkali-rich, high-silica melt rock suggest initially high temperatures followed by rapid cooling.

The effects of the Chesapeake Bay impact crater on the geologic framework and the correlation of hydrogeologic units of southeastern Virginia, south of the James River

USGS Publications Warehouse

Powars, David S.

2000-01-01

About 35 million years ago, a large comet or meteor slammed into the shallow shelf on the western margin of the Atlantic Ocean, creating the Chesapeake Bay impact crater. This report, the second in a series, refines the geologic framework of southeastern Virginia, south of the James River in and near the impact crater, and presents evidence for the existence of a pre-impact James River structural zone. The report includes detailed correlations of core lithologies with borehole geophysical logs; the correlations provide the foundation for the compilation of stratigraphic cross sections. These cross sections are tied into the geologic framework of the lower York-James Peninsula as presented in the first report in the series, Professional Paper 1612

Effects of shoreline discharge of iron mine tailings on a marine soft-bottom community in northern Chile.

PubMed

Lancellotti, D A; Stotz, W B

2004-02-01

This study evaluates the magnitude and extension of the impact produced by the discharge of inert allochthonous materials, including clays and particulate iron, on macrobenthic soft-bottom assemblages in the subtidal zone of a coastal bay in north-central Chile. An average of 118 Ton h(-1) of finely divided solids were discharged into the rocky intertidal zone of the bay for a period of over 16 years, producing continuous turbidity in the water column and sedimentation in the subtidal zone. Data obtained four months before cessation of the discharge showed that the macrofauna present at 20 and 50 m depth in the bay suffered an important decrease in abundance and species richness, low diversity/high dominance, and deep changes in community structure related to the discharge. The faunal assemblages present at 110 m depth did not show effects from the discharge, suggesting that the impact was limited to the inner part of the bay. The impoverished faunal aggregates at 20 and 50 m depth showed exclusive domination by the Lumbrineris bifilaris (polychaete)-Diastylis tongoyensis (cumacean) association, representing a simple trophic guild of deposit feeders. The complete absence of opportunistic species such as capitellid, spionid, and/or cirratulid polychaetes may be associated with the turbidity and sedimentation levels in the bay.

Chesapeake Bay impact structure: Morphology, crater fill, and relevance for impact structures on Mars

USGS Publications Warehouse

Horton, J. Wright; Ormo, J.; Powars, D.S.; Gohn, G.S.

2006-01-01

The late Eocene Chesapeake Bay impact structure (CBIS) on the Atlantic margin of Virginia is one of the largest and best-preserved "wet-target" craters on Earth. It provides an accessible analog for studying impact processes in layered and wet targets on volatile-rich planets. The CBIS formed in a layered target of water, weak clastic sediments, and hard crystalline rock. The buried structure consists of a deep, filled central crater, 38 km in width, surrounded by a shallower brim known as the annular trough. The annular trough formed partly by collapse of weak sediments, which expanded the structure to ???85 km in diameter. Such extensive collapse, in addition to excavation processes, can explain the "inverted sombrero" morphology observed at some craters in layered targets. The distribution of crater-fill materials i n the CBIS is related to the morphology. Suevitic breccia, including pre-resurge fallback deposits, is found in the central crater. Impact-modified sediments, formed by fluidization and collapse of water-saturated sand and silt-clay, occur in the annular trough. Allogenic sediment-clast breccia, interpreted as ocean-resurge deposits, overlies the other impactites and covers the entire crater beneath a blanket of postimpact sediments. The formation of chaotic terrains on Mars is attributed to collapse due to the release of volatiles from thick layered deposits. Some flat-floored rimless depressions with chaotic infill in these terrains are impact craters that expanded by collapse farther than expected for similar-sized complex craters in solid targets. Studies of crater materials in the CBIS provide insights into processes of crater expansion on Mars and their links to volatiles. ?? The Meteoritical Society, 2006.

Magnetic Properties of Three Impact Structures in Canada

NASA Astrophysics Data System (ADS)

Scott, R. G.; Pilkington, M.; Tanczyk, E. I.; Grieve, R. A. F.

1995-09-01

Magnetic anomaly lows associated with the West Hawk Lake (Manitoba), Deep Bay (Saskatchewan) and Clearwater Lakes (Quebec) impact structures, are variable in lateral extent and intensity, a characteristic shared with most impact structures [1]. Drill core from the centres of these structures provides a unique opportunity to ground truth the causes of the reduction in magnetic field intensity in impact structures. Magnetic susceptibility and remanent magnetization levels have been found to be well below regional levels in melt rocks, impact breccias, fractured/shocked basement rocks in the central uplifts, and post-impact sediments. Deep Bay, formed in Pre-Cambrian paragneisses, is a complex crater with a submerged central uplift. It has been extensively infilled with non-magnetic black shales of Cretaceous age [2]. An airborne magnetic low of about 100 nT is associated with the Deep Bay structure. Below the shales and along the rim of the structure are highly brecciated country rocks with variable amounts of very fine rock flour. Susceptibility and remanent magnetization are both weak due to extensive alteration in the brecciated rocks. Alteration of the brecciated rocks, and the effect of several hundred meters of non-magnetic sedimentary infill, both contribute to the magnetic low. West Hawk Lake, a simple crater, was excavated in metavolcanic and metasedimentary rocks of the Superior Province [3], and has a ground magnetic low of about 250 nT. As with Deep Bay, West Hawk Lake has been infilled with dominantly non-magnetic sediments. Brecciation and alteration are extensive, with breccia derived from greenschist-facies meta-andesite displaying slightly higher susceptibilities and remanent magnetizations than breccia derived from the more felsic metasediments. Brecciation has effectively randomized magnetization vectors, and subsequent alteration resulted in the destruction of magnetic phases. These two factors contribute to the magnetic low over this structure. The Clearwater Lakes impact structures are two complex craters formed in Archean retrograde granulite facies rocks [4]. Clearwater West, at 36 km diameter, has an annular ring of islands and a shallowly submerged central uplift. Clearwater East, at 26 km diameter, has a more deeply submerged central uplift. The structures are characterised by highly oxidized melt rock and melt- breccia lenses exposed at the surface. Shocked crystalline basement rocks and minor amounts of breccia and melt rock occur in the central uplifts [5]. Despite relatively little alteration at depth, these rocks exhibit both susceptibilities and remanent magnetizations well below the regionally high values. The Clearwater rocks also contain a thermoremanent reversed magnetization, acquired at the time of impact, and characteristic of the Permo-Carboniferous Reversed Polarity Superchron. The magnetization is carried by titanomagnetite in Clearwater West, and both magnetite and pyrrhotite in Clearwater East. This reversed magnetization contributes to the magnetic low, but cannot account for all of it. The intense airborne magnetic low (> 500 nT) requires a significant contribution from the shocked basement at depth, produced by either alteration of magnetic phases along fractures, or reduction in magnetic properties by lower shock levels away from the point of impact [6]. References: [1] Pilkington M. and Grieve R. A. F. (1992) Rev. Geophys., 30, 161-181. [2] Innes M. J. S. et al. (1964) Publ. Dom. Obs. Ottawa, 31, 19-52. [3] Halliday I. and Griffin A. A. (1967) J. Roy. Astron. Soc. Can., 61, 1-8. [4] Simonds C. H. et al. (1978) LPS IX, 2633-2658. [5] Hische R. (1994) Unpublished Ph.D. thesis, Munster. [6] Pohl J. (1994) 3rd Intl. Wkshp., ESF Network Impact Cratering and Evol. of Planet Earth, Shockwave Behavior in Nature and Expt., Progr. Abstr., 51.

76 FR 59423 - Drakes Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement, Point Reyes...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-26

... Bay Oyster Company Special-Use Permit, Draft Environmental Impact Statement, Point Reyes National... Drakes Bay Oyster Company Special-use permit in Drakes Estero, Point Reyes National Seashore, California... site, at http://parkplanning.nps.gov/pore (click on the Drakes Bay Oyster Company Special-use permit...

Pore-water chemistry from the ICDP-USGS coer hole in the Chesapeake Bay impact structure--Implications for paleohydrology, microbial habitat, and water resources

USGS Publications Warehouse

Sanford, Ward E.; Voytek, Mary A.; Powars, David S.; Jones, Blair F.; Cozzarelli, Isabelle M.; Eganhouse, Robert P.; Cockell, Charles S.

2009-01-01

We investigated the groundwater system of the Chesapeake Bay impact structure by analyzing the pore-water chemistry in cores taken from a 1766-m-deep drill hole 10 km north of Cape Charles, Virginia. Pore water was extracted using high-speed centrifuges from over 100 cores sampled from a 1300 m section of the drill hole. The pore-water samples were analyzed for major cations and anions, stable isotopes of water and sulfate, dissolved and total carbon, and bioavailable iron. The results reveal a broad transition between fresh and saline water from 100 to 500 m depth in the post-impact sediment section, and an underlying syn-impact section that is almost entirely filled with brine. The presence of brine in the lowermost post-impact section and the trend in the dissolved chloride with depth suggest a transport process dominated by molecular diffusion and slow, compaction-driven, upward flow. Major ion results indicate residual effects of diagenesis from heating, and a pre-impact origin for the brine. High levels of dissolved organic carbon (6-95 mg/L) and the distribution of electron acceptors indicate an environment that may be favorable for microbial activity throughout the drilled section. The concentration and extent of the brine is much greater than had previously been observed, suggesting its occurrence may be common in the inner crater. However, groundwater flow conditions in the structure may reduce the salt-water-intrusion hazard associated with the brine.

Diagnosis of potential stressors adversely affecting benthic invertebrate communities in Greenwich Bay, Rhode Island, USA.

PubMed

Pelletier, Marguerite; Ho, Kay; Cantwell, Mark; Perron, Monique; Rocha, Kenneth; Burgess, Robert M; Johnson, Roxanne; Perez, Kenneth; Cardin, John; Charpentier, Michael A

2017-02-01

Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was impaired. Second, the presence of source, stressor, and effect were established. Then linkages between source, stressor, and effect were developed. This allows identification of probable stressors adversely affecting the waterbody. Three pollutant categories were assessed: chemicals, nutrients, and suspended sediments. This weight of evidence approach indicated that Greenwich Bay was primarily impacted by eutrophication-related stressors. The sediments of Greenwich Bay were carbon enriched and low dissolved oxygen concentrations were commonly seen, especially in the western portions of Greenwich Bay. The benthic community was depauperate, as would be expected under oxygen stress. Although our analysis indicated that contaminant loads in Greenwich Bay were at concentrations where adverse effects might be expected, no toxicity was observed, as a result of high levels of organic carbon in these sediments reducing contaminant bioavailability. Our analysis also indicated that suspended sediment impacts were likely nonexistent for much of the Bay. This analysis demonstrates that the diagnostic procedure was useful to organize and assess the potential stressors impacting the ecological well-being of Greenwich Bay. This diagnostic procedure is useful for management of waterbodies impacted by multiple stressors. Environ Toxicol Chem 2017;36:449-462. © 2016 SETAC. © 2016 SETAC.

Coesite in suevites from the Chesapeake Bay impact structure

USGS Publications Warehouse

Jackson, John C.; Horton, J. Wright; Chou, I-Ming; Belkin, Harvey E.

2016-01-01

The occurrence of coesite in suevites from the Chesapeake Bay impact structure is confirmed within a variety of textural domains in situ by Raman spectroscopy for the first time and in mechanically separated grains by X-ray diffraction. Microtextures of coesite identified in situ investigated under transmitted light and by scanning electron microscope reveal coesite as micrometer-sized grains (1–3 μm) within amorphous silica of impact-melt clasts and as submicrometer-sized grains and polycrystalline aggregates within shocked quartz grains. Coesite-bearing quartz grains are present both idiomorphically with original grain margins intact and as highly strained grains that underwent shock-produced plastic deformation. Coesite commonly occurs in plastically deformed quartz grains within domains that appear brown (toasted) in transmitted light and rarely within quartz of spheroidal texture. The coesite likely developed by a mechanism of solid-state transformation from precursor quartz. Raman spectroscopy also showed a series of unidentified peaks associated with shocked quartz grains that likely represent unidentified silica phases, possibly including a moganite-like phase that has not previously been associated with coesite.

78 FR 34093 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-06

... scientific and technical information presented in the report, the realistic mining scenario used, the data... Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY: Environmental Protection Agency... document titled, ``An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska...

What a difference a bay makes: natural variation in dietary resources mediates growth in a recently settled herbivorous fish

NASA Astrophysics Data System (ADS)

Priest, Mark A.; Halford, Andrew R.; Clements, Kendall D.; Douglas, Emily; Abellana, Sheena L.; McIlwain, Jennifer L.

2016-12-01

Processes acting during the early stages of coral reef fish life cycles have a disproportionate influence on their adult abundance and community structure. Higher growth rates, for example, confer a major fitness advantage in larval and juvenile fishes, with larger fish undergoing significantly less mortality. The role of dietary resources in the size-structuring process has not been well validated, especially at the early post-settlement phase, where competition and predation are seen as preeminent drivers of juvenile fish assemblage structure. Here, we report on a size differential of 10-20% between recently settled Siganus spinus rabbitfish recruits from different bays around the Pacific island of Guam. This difference was maintained across multiple recruitment events within and between years. After confirming the validity of our observations through otolith increment analysis, subsequent investigation into the drivers of this variation revealed significant differences in the structure of algal assemblages between bays, congruent with the observed differences in size of the recently settled fish. Gut analyses showed a greater presence of algal types with higher levels of nitrogen and phosphorus in the stomachs of fish from Tanguisson, the bay with the largest observed recruits. To ensure this mechanism was one of causation and not correlation, we conducted a fully factorial experiment in which S. spinus recruits sampled from different bays were reared on all combinations of algal diets representative of the different bays. Recruits on the `Tanguisson' diet grew faster than recruits on other diets, regardless of their origin. We propose that the greater availability of high-quality dietary resources at this location is likely conferring benefits that impact on the population-level dynamics of this species. The spatial and temporal extent of this process clearly implicates food as a limiting resource, capable of mediating fish population dynamics at multiple spatial scales and ontogenetic phases.

Oceanographic characteristics of an impacted coastal bay: Baía de Guanabara, Rio de Janeiro, Brazil

NASA Astrophysics Data System (ADS)

Kjerfve, Björn; Ribeiro, Cesar H. A.; Dias, Gilberto T. M.; Filippo, Alessandro M.; Da Silva Quaresma, Valéria

1997-11-01

Baía de Guanabara is a 384 km 2 eutrophic coastal bay in Brazil, impacted by the polluted discharge from the Rio de Janeiro metropolitan area. The structurally controlled bay has a central channel with a depth of 30 m and a sandy bottom near the entrance, reflecting wave and tidal forcing. In contrast, the bay-averaged water depth is 5.7 m and the bottom sediments are mostly muds as a result of the Holocene transgression and rapid fluvial sedimentation, accelerated by channelization of rivers and deforestation. An extensive sand bank is located seaward of the bay entrance and a flood-oriented sand wave system indicates sand transport into the bay. The mean freshwater discharge measures 100±59 m 3 s -1 and is greatest in the rainy austral summer in December and January. Tides are mixed mainly semidiurnal with a range of 0.7 m, and peak spring tidal currents reach 0.5 m s -1 inside the bay and 1.6 m s -1 near the bay entrance. The passage of northward propagating polar fronts results in regular strong southwesterly winds and heavy wave forcing. The bay has mean salinities from 21.0 to 34.5‰ with an average of 29.5±4.8‰. The vertical salinity stratification, Δs/s, varies from 0.06 to 0.21 and is relatively weak and inversely proportional to rms tidal currents. The residual circulation is characterized by both gravitational circulation and transverse residual tidal circulation, measuring 800 and 400 m 3 s -1 respectively. The renewal time of 50% of the bay water volume is 11.4 days. Untreated sewage runoff enters the bay from the west, resulting in locally poor water quality, where the near-bottom mean dissolved oxygen measures only 3.1 mg 1 -1 and results in anoxic bottom muds. The worst water quality is indicated by average fecal coliform of 1140 counts ml -1 and excessive ammonia and phosphate loading. The average chlorophyll concentration in this region responds to the nutrient loading and exceeds 130 μg 1 -1 although 57 μg 1 -1 is the overall mean for the bay. The atomic N:P ratio measures 14 for the bay as a whole.

Diagnosis of potential stressors adversely affecting benthic ...

EPA Pesticide Factsheets

Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was impaired. Second, the presence of source, stressor, and effect were established. Then linkages between source, stressor, and effect were developed. This allows identification of probable stressors adversely affecting the waterbody. Three pollutant categories were assessed: chemicals, nutrients, and suspended sediments. This weight of evidence approach indicated that Greenwich Bay was primarily impacted by eutrophication-related stressors. The sediments of Greenwich Bay were carbon enriched and low dissolved oxygen concentrations were commonly seen, especially in the western portions of Greenwich Bay. The benthic community was depauperate, as would be expected under oxygen stress. Although our analysis indicated that contaminant loads in Greenwich Bay were at concentrations where adverse effects might be expected, no toxicity was observed, as a result of high levels of organic carbon in these sediments reducing contaminant bioavailability. Our analysis also indicated that suspended sediment impacts were likely nonexistent for much of the Bay. This analysis demonstrates that the diagnostic procedure was useful to organize and assess the potential stressors impacting the ecological well-being

Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): An ecological network analysis

NASA Astrophysics Data System (ADS)

Meddeb, Marouan; Grami, Boutheïna; Chaalali, Aurélie; Haraldsson, Matilda; Niquil, Nathalie; Pringault, Olivier; Sakka Hlaili, Asma

2018-03-01

The study is the first attempt to (i) model spring food webs in three SW Mediterranean ecosystems which are under different anthropogenic pressures and (ii) to project the consequence of this stress on their function. Linear inverse models were built using the Monte Carlo method coupled with Markov Chains to characterize the food-web status of the Lagoon, the Channel (inshore waters under high eutrophication and chemical contamination) and the Bay of Bizerte (offshore waters under less anthropogenic pressure). Ecological network analysis was used for the description of structural and functional properties of each food web and for inter-ecosystem comparisons. Our results showed that more carbon was produced by phytoplankton in the inshore waters (966-1234 mg C m-2 d-1) compared to the Bay (727 mg C m-2 d-1). The total ecosystem carbon inputs into the three food webs was supported by high primary production, which was mainly due to >10 μm algae. However, the three carbon pathways were characterized by low detritivory and a high herbivory which was mainly assigned to protozooplankton. This latter was efficient in channelling biogenic carbon. In the Lagoon and the Channel, foods webs acted almost as a multivorous structure with a tendency towards herbivorous one, whereas in the Bay the herbivorous pathway was more dominant. Ecological indices revealed that the Lagoon and the Channel food webs/systems had high total system throughput and thus were more active than the Bay. The Bay food web, which had a high relative ascendency value, was more organized and specialized. This inter-ecosystem difference could be due to the varying levels of anthropogenic impact among sites. Indeed, the low value of Finn's cycling index indicated that the three systems are disturbed, but the Lagoon and the Channel, with low average path lengths, appeared to be more stressed, as both sites have undergone higher chemical pollution and nutrient loading. This study shows that ecosystem models combined with ecological indices provide a powerful approach to detect change in environmental status and anthropogenic impacts.

Assessment and physiological state of the Posidonia oceanica meadows in Porto Cristo (Manacor, Spain)

NASA Astrophysics Data System (ADS)

Sureda, Antoni; Box, Antonio; Tejada, Silvia

2015-12-01

In the Mediterranean Sea, Posidonia oceanica is the main seagrass meadow that brings food and shelter to many species. The P. oceanica deterioration is an indicator of its own status, since it is sensitive to many disturbances, such as human impacts or alien species. Lately, oxidative stress has been pointed out as another possible biomarker of the animal and plant status. The aim of this work was to evaluate the physiological status of the P. oceanica meadows in the Porto Cristo bay (Manacor, Mallorca, Balearic Islands, Western Mediterranean), evaluating the possible impact induced by human activity performed in the area. In situ measurements were quantified (shoot density, and the maximum length and width of P. oceanica leaves) by scuba divers. Leaf samples were collected to determine the catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. The malondialdehyde (MDA) level as marker of lipid peroxidation was also evaluated. Shoot density, and length and width measurements of the leaves in the inner locations of the bay showed inferior structural features than the leaves from the outer areas. CAT, SOD and GPx enzymatic activities and lipid peroxidation were higher in leaves from the internal zones than in the outer placements. In conclusion, the general status of the of P. oceanica meadows on the Porto Cristo Bay according to structural and oxidative biomarkers evidenced a good physiological condition, although the areas nearest to the harbour and the beach reflect signs of human affection. Altogether, it reflects a good physiological condition of the meadows in the external areas of the Porto Cristo Bay.

Supplemental materials for the ICDP-USGS Eyreville A, B, and C core holes, Chesapeake Bay impact structure: Core-box photographs, coring-run tables, and depth-conversion files

USGS Publications Warehouse

Durand, C.T.; Edwards, L.E.; Malinconico, M.L.; Powars, D.S.

2009-01-01

During 2005-2006, the International Continental Scientific Drilling Program and the U.S. Geological Survey drilled three continuous core holes into the Chesapeake Bay impact structure to a total depth of 1766.3 m. A collection of supplemental materials that presents a record of the core recovery and measurement data for the Eyreville cores is available on CD-ROM at the end of this volume and in the GSA Data Repository. The supplemental materials on the CD-ROM include digital photographs of each core box from the three core holes, tables of the three coring-run logs, as recorded on site, and a set of depth-conversion programs. In this chapter, the contents, purposes, and basic applications of the supplemental materials are briefly described. With this information, users can quickly decide if the materials will apply to their specific research needs. ?? 2009 The Geological Society of America.

Evaluation of a Compression-Loaded-Stitched-Multi-Bay Fuselage Panel With Barely Visible Impact Damage

NASA Technical Reports Server (NTRS)

Baker, Donald J.; Li, Ji-An

2005-01-01

The experimental results from a stitched VaRTM carbon-epoxy composite panel tested under uni-axial compression loading are presented along with nonlinear finite element analysis prediction of the response. The curved panel is divided by frames and stringers into six bays with a column of three bays along the compressive loading direction. The frames are supported at the frame ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field-displacement measurement technique that utilizes a camera-based-stereo-vision system was used to record the displacements. The panel was loaded to 1.5 times the predicted initial buckling load (1st bay buckling load, P(sub er) from the nonlinear finite element analysis and then was removed from the test machine for impact testing. After impacting with 20 ft-lbs of energy using a spherical impactor to produce barely visible damage the panel was loaded in compression until failure. The buckling load of the first bay to buckle was 97% of the buckling load before impact. The stitching constrained the impact damage from growing during the loading to failure. Impact damage had very little overall effect on panel stiffness. Panel stiffness measured by the full-field-displacement technique indicated a 13% loss in stiffness after impact. The panel failed at 1.64 times the first panel buckling load. The barely visible impact damage did not grow noticeably as the panel failed by global instability due to stringer-web terminations at the frame locations. The predictions from the nonlinear analysis of the finite element modeling of the entire specimen were very effective in the capture of the initial buckling and global behavior of the panel. In addition, the prediction highlighted the weakness of the panel under compression due to stringer web terminations. Both the test results and the nonlinear predictions serve to reinforce the severe penalty in structural integrity caused by the low cost manufacturing technique to terminate the stringer webs, and demonstrates the importance of this type of sub-component testing and high fidelity failure analysis in the design of a composite fuselage.

Recent research on the Chesapeake Bay impact structure, USA - Impact debris and reworked ejecta

USGS Publications Warehouse

Horton, J. Wright; Aleinikoff, John N.; Kunk, Michael J.; Gohn, Gregory S.; Edwards, Lucy E.; Self-Trail, Jean M.; Powars, David S.; Izett, Glen A.

2005-01-01

Four new coreholes in the western annular trough of the buried, late Eocene Chesapeake Bay impact structure provide samples of shocked minerals, cataclastic rocks, possible impact melt, mixed sediments, and damaged microfossils. Parautochthonous Cretaceous sediments show an upward increase in collapse, sand fluidization, and mixed sediment injections. These impact-modified sediments are scoured and covered by the upper Eocene Exmore beds, which consist of highly mixed Cretaceous to Eocene sediment clasts and minor crystalline-rock clasts in a muddy quartz-glauconite sand matrix. The Exmore beds are interpreted as seawater-resurge debris flows. Shocked quartz is found as sparse grains and in rock fragments at all four sites in the Exmore, where these fallback remnants are mixed into the resurge deposit. Crystalline-rock clasts that exhibit shocked quartz or cataclastic fabrics include felsites, granitoids, and other plutonic rocks. Felsite from a monomict cataclasite boulder has a sensitive high-resolution ion microprobe U-Pb zircon age of 613 ± 4 Ma. Leucogranite from a polymict cataclasite boulder has a similar Neoproterozoic age based on muscovite 40Ar/39Ar data. Potassium-feldspar 40Ar/39Ar ages from this leucogranite show cooling through closure (∼150 °C) at ca. 261 Ma without discernible impact heating. Spherulitic felsite is under investigation as a possible impact melt. Types of crystalline clasts, and exotic sediment clasts and grains, in the Exmore vary according to location, which suggests different provenances across the structure. Fractured calcareous nannofossils and fused, bubbled, and curled dinoflagellate cysts coexist with shocked quartz in the Exmore, and this damage may record conditions of heat, pressure, and abrasion due to impact in a shallow-marine environment.

Dynamical Influence and Operational Impacts of an Extreme Mediterranean Cold Surge

DTIC Science & Technology

2013-06-01

over 45 cm of snowfall in Souda Bay, Crete, which significantly impacted operations at Naval Support Activity Souda Bay. The extratropical wave...cold surge event and its dependence on the upstream synoptic scale events. 14. SUBJECT TERMS Extratropical Cyclone, Souda Bay...Activity Souda Bay. The extratropical wave associated with the cold surge could be classified as a classic life-cycle 1 wave break. The wave-breaking

Spatiotemporal analysis of gene flow in Chesapeake Bay Diamondback Terrapins (Malaclemys terrapin)

USGS Publications Warehouse

Converse, Paul E.; Kuchta, Shawn R; Roosenburg, Willem R; Henry, Paula F.; Haramis, G. Michael; King, Timothy L.

2015-01-01

There is widespread concern regarding the impacts of anthropogenic activities on connectivity among populations of plants and animals, and understanding how contemporary and historical processes shape metapopulation dynamics is crucial for setting appropriate conservation targets. We used genetic data to identify population clusters and quantify gene flow over historical and contemporary time frames in the Diamondback Terrapin (Malaclemys terrapin). This species has a long and complicated history with humans, including commercial over-harvesting and subsequent translocation events during the early twentieth century. Today, terrapins face threats from habitat loss and mortality in fisheries bycatch. To evaluate population structure and gene flow among Diamondback Terrapin populations in the Chesapeake Bay region, we sampled 617 individuals from 15 localities, and screened individuals at 12 polymorphic microsatellite loci. Our goals were to demarcate metapopulation structure, quantify genetic diversity, estimate effective population sizes, and document temporal changes in gene flow. We found that terrapins in the Chesapeake Bay region harbor high levels of genetic diversity and form four populations. Effective population sizes were variable. Among most population comparisons, estimates of historical and contemporary terrapin gene flow were generally low (m ≈ 0.01). However, we detected a substantial increase in contemporary gene flow into Chesapeake Bay from populations outside the bay, as well as between two populations within Chesapeake Bay, possibly as a consequence of translocations during the early twentieth century. Our study shows that inferences across multiple time scales are needed to evaluate population connectivity, especially as recent changes may identify threats to population persistence.

Potential climate-change impacts on the Chesapeake Bay

Treesearch

Raymond G. Najjar; Christopher R. Pyke; Mary Beth Adams; Denise Breitburg; Carl Hershner; Michael Kemp; Robert Howarth; Margaret R. Mulholland; Michael Paolisso; David Secor; Kevin Sellner; Denice Wardrop; Robert Wood

2010-01-01

We review current understanding of the potential impact of climate change on the Chesapeake Bay. Scenarios for CO2 emissions indicate that by the end of the 21st century the Bay region will experience significant changes in climate forcings with respect to historical conditions, including increases in CO2 concentrations,...

Geologic columns for the ICDP-USGS Eyreville B core, Chesapeake Bay impact structure: Impactites and crystalline rocks, 1766 to 1096 m depth

USGS Publications Warehouse

Horton, J. Wright; Gibson, R.L.; Reimold, W.U.; Wittmann, A.; Gohn, G.S.; Edwards, L.E.

2009-01-01

The International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville drill cores from the Chesapeake Bay impact structure provide one of the most complete geologic sections ever obtained from an impact structure. This paper presents a series of geologic columns and descriptive lithologic information for the lower impactite and crystalline-rock sections in the cores. The lowermost cored section (1766-1551 m depth) is a complex assemblage of mica schists that commonly contain graphite and fibrolitic sillimanite, intrusive granite pegmatites that grade into coarse granite, and local zones of mylonitic deformation. This basement-derived section is variably overprinted by brittle cataclastic fabrics and locally cut by dikes of polymict impact breccia, including several suevite dikes. An overlying succession of suevites and lithic impact breccias (1551-1397 m) includes a lower section dominated by polymict lithic impact breccia with blocks (up to 17 m) and boulders of cataclastic gneiss and an upper section (above 1474 m) of suevites and clast-rich impact melt rocks. The uppermost suevite is overlain by 26 m (1397-1371 m) of gravelly quartz sand that contains an amphibolite block and boulders of cataclasite and suevite. Above the sand, a 275-m-thick allochthonous granite slab (1371-1096 m) includes gneissic biotite granite, fine- and medium-to-coarse-grained biotite granites, and red altered granite near the base. The granite slab is overlain by more gravelly sand, and both are attributed to debris-avalanche and/or rockslide deposition that slightly preceded or accompanied seawater-resurge into the collapsing transient crater. ?? 2009 The Geological Society of America.

Spatial distribution of dinoflagellates from the tropical coastal waters of the South Andaman, India: Implications for coastal pollution monitoring.

PubMed

Narale, Dhiraj Dhondiram; Anil, Arga Chandrashekar

2017-02-15

Dinoflagellate community structure from two semi-enclosed areas along the South Andaman region, India, was investigated to assess the anthropogenic impact on coastal water quality. At the densely inhabited Port Blair Bay, the dominance of mixotrophs in water and Protoperidinoids in sediments was attributed to anthropogenic nutrient enrichment and prey availability. A significant decrease in dinoflagellate abundance from inner to outer bay emphasize the variation in nutrient availability. The dominance of autotrophs and Gonyaulacoid cysts at the North Bay highlight low nutrient conditions with less anthropogenic pressure. The occurrence of oceanic Ornithocercus steinii and Diplopsalis sp. could evince the oceanic water intrusion into the North Bay. Nine potentially harmful and red-tide-forming species including Alexandrium tamarense complex, A. minutum were identified in this study. Although there are no harmful algal bloom (HABs) incidences in this region so far, increasing coastal pollution could support their candidature towards the future HABs initiation and development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Volcanisme, activité anthropique et circulation des masses océaniques : leur influence respective sur la distribution des populations d'ostracodes dans la baie de Kagoshima (île de Kyushu, Japon)Impact of volcanism, human activities, and water mass circulation on the distribution of ostracod populations in Kagoshima Bay (Kyushu Island, southern Japan)

NASA Astrophysics Data System (ADS)

Bodergat, Anne-Marie; Oki, Kimihiko; Ishizaki, Kunihiro; Rio, Michel

2002-11-01

The distribution of ostracod populations in Kagoshima Bay (Japan) is analysed with reference to different environmental parameters. The bay is an area of volcanic activity of Sakurajima volcano under the influence of the Kuroshio Current. Most of the Head environment is occupied by an acidic water mass. Numbers of individual and species decrease from the Mouth of the bay towards the Basin and Head environments. In this latter, acidic water mass has a drastic effect on ostracod populations, whereas volcanic ashes and domestic inputs are not hostile. Ostracod distribution is influenced by the quality and structure of water masses. To cite this article: A.-M. Bodergat et al., C. R. Geoscience 334 (2002) 1053-1059.

Detection of environmental impacts of shrimp farming through multiple lines of evidence.

PubMed

Hatje, Vanessa; de Souza, Manuel M; Ribeiro, Luisa F; Eça, Gilmara F; Barros, Francisco

2016-12-01

In order to evaluate the impact of semi-intensive shrimp farming, comparisons between Control and Impact areas were made based on multiple lines of evidence using an asymmetrical design. Water and sediment samples were collected in four shrimp farms located in Todos os Santos Bay, Bahia, Brazil. Nutrients, trace elements and macrobenthic assemblages were evaluated using uni- and multivariate analyzes. Significant differences were observed between Impact and Control areas for the water column dataset (i.e., ancillary variables, SPM, dissolved nutrients and major and trace elements in SPM), whereas no significant differences were observed for the chemistry of sediments. Macrobenthic assemblages were negatively affected by shrimp farm activities. Impacted sites presented the lowest abundance, richness and different structure of macrofaunal benthic assemblages. Farms clearly produced negative impacts in the Todos os Santos Bay. This conclusion was only possible to be reached through the use of multiple lines of evidence. Chemistry and benthic assemblages data combined produced a better description of the quality and impacts of the evaluated environments. Different conclusions would have been reached if chemistry and ecology results were studied separately vs. together. Copyright © 2016 Elsevier Ltd. All rights reserved.

78 FR 25266 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-30

... information presented in the report, the realistic mining scenario used, the data and information used to... additional data or scientific or technical information about Bristol Bay resources or large-scale mining that... Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY: Environmental Protection Agency...

Comparison of structural performance of one- and two-bay rotary joints for truss applications

NASA Technical Reports Server (NTRS)

Vail, J. Douglas; Lake, Mark S.

1991-01-01

The structural performance of one- and two-bay large-diameter discrete-bearing rotary joints was addressed for application to truss-beam structures such as the Space Station Freedom. Finite element analyses are performed to determine values for rotary joint parameters that give the same bending vibration frequency as the parent truss beam. The structural masses and maximum internal loads of these joints are compared to determine their relative structural efficiency. Results indicate that no significant difference exists in the masse of one- and two-bay rotary joints. This conclusion is reinforced with closed-form calculations of rotary joint structural efficiency in extension. Also, transition truss-member loads are higher in the one-bay rotary joint. However, because of the increased buckling strength of these members, the external load-carrying capability of the one-bay concept is higher than that of the two-bay concept.

Use of Historic Data to Understand Benthic Community Changes in Narragansett Bay

EPA Science Inventory

Narragansett Bay, a small northeastern U.S. estuary has been adversely impacted by eutrophication. Nitrogen loads in the Bay have risen as human development has increased, and the Bay shows a distinct eutrophication gradient from the head of the bay to the mouth. Sewage treatme...

Microbial abundance in the deep subsurface of the Chesapeake Bay impact crater: Relationship to lithology and impact processes

USGS Publications Warehouse

Cockell, Charles S.; Gronstal, Aaron L.; Voytek, Mary A.; Kirshtein, Julie D.; Finster, Kai; Sanford, Ward E.; Glamoclija, Mihaela; Gohn, Gregroy S.; Powars, David S.; Horton, J. Wright

2009-01-01

Asteroid and comet impact events are known to cause profound disruption to surface ecosystems. The aseptic collection of samples throughout a 1.76-km-deep set of cores recovered from the deep subsurface of the Chesapeake Bay impact structure has allowed the study of the subsurface biosphere in a region disrupted by an impactor. Microbiological enumerations suggest the presence of three major microbiological zones. The upper zone (127–867 m) is characterized by a logarithmic decline in microbial abundance from the surface through the postimpact section of Miocene to Upper Eocene marine sediments and across the transition into the upper layers of the impact tsunami resurge sediments and sediment megablocks. In the middle zone (867–1397 m) microbial abundances are below detection. This zone is predominantly quartz sand, primarily composed of boulders and blocks, and it may have been mostly sterilized by the thermal pulse delivered during impact. No samples were collected from the large granite block (1096–1371 m). The lowest zone (below 1397 m) of increasing microbial abundance coincides with a region of heavily impact-fractured, hydraulically conductive suevite and fractured schist. These zones correspond to lithologies influenced by impact processes. Our results yield insights into the influence of impacts on the deep subsurface biosphere.

Origin and emplacement of impactites in the Chesapeake Bay impact structure, Virginia, USA

USGS Publications Warehouse

Horton, J. Wright; Gohn, G.S.; Powars, D.S.; Edwards, L.E.

2007-01-01

The late Eocene Chesapeake Bay impact structure, located on the Atlantic margin of Virginia, may be Earth's best-preserved large impact structure formed in a shallow marine, siliciclastic, continental-shelf environment. It has the form of an inverted sombrero in which a central crater ???40 km in diameter is surrounded by a shallower brim, the annular trough, that extends the diameter to ???85 km. The annular trough is interpreted to have formed largely by the collapse and mobilization of weak sediments. Crystalline-clast suevite, found only in the central crater, contains clasts and blocks of shocked gneiss that likely were derived from the fragmentation of the central-uplift basement. The suevite and entrained megablocks are interpreted to have formed from impact-melt particles and crystalline-rock debris that never left the central crater, rather than as a fallback deposit. Impact-modified sediments in the annular trough include megablocks of Cretaceous nonmarine sediment disrupted by faults, fluidized sands, fractured clays, and mixed-sediment intercalations. These impact-modified sediments could have formed by a combination of processes, including ejection into and mixing of sediments in the water column, rarefaction-induced fragmentation and clastic injection, liquefaction and fluidization of sand in response to acoustic-wave vibrations, gravitational collapse, and inward lateral spreading. The Exmore beds, which blanket the entire crater and nearby areas, consist of a lower diamicton member overlain by an upper stratified member. They are interpreted as unstratified ocean-resurge deposits, having depositional cycles that may represent stages of inward resurge or outward anti-resurge flow, overlain by stratified fallout of suspended sediment from the water column. ?? 2008 The Geological Society of America. All rights reserved.

Gulf of Mexico integrated science - Tampa Bay study, the impact of groundwater and contaminants on Tampa Bay

USGS Publications Warehouse

Swarzenski, Peter W.

2005-01-01

Despite the recreational and economic value of coastal bays and estuaries, these ecosystems are often among our most 'troubled' natural environments. Urbanization, agriculture, mining, and shipping are just a few activities that can have a profound and lasting impact on the coastal zone. In order to maintain a healthy coastal ecosystem, it is crucial to develop reasonable management practices around expert scientific information. We still have much to learn about the quantity and quality of groundwater being discharged into Tampa Bay, Florida. We also need to improve our knowledge of a wide range of contaminants entering the bay and must be able to determine where they accumulate in seafloor sediments. Such buried contaminants can potentially be harmful to biota if they are released to the water column. U.S. Geological Survey (USGS) scientists and research partners from the University of South Florida (USF), the University of Florida (UF), and the Florida Marine Research Institute (FMRI) are mapping sources of groundwater, measuring groundwater flow into Tampa Bay, and assessing the impact of contaminants and sediments on bay water quality and ecosystem health.

Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay

DTIC Science & Technology

2010-06-01

35805 3 Pacific Northwest National Laboratory 1529 W. Sequim Bay Rd. Sequim , WA 98382 4 University of South Carolina Columbia, SC 5 Tetra...Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay ...land use change. Mobile Bay , AL is a designated pilot region of the Gulf of Mexico Alliance (GOMA) and is the focus area of many current NASA and

Evaluation of effects of shellfish aquaculture and capture fishery on a semi-closed bay ecosystem

NASA Astrophysics Data System (ADS)

Han, Dongyan; Chen, Yong; Zhang, Chongliang; Ren, Yiping; Xu, Binduo; Xue, Ying

2018-07-01

Coastal waters in the world are suffering from multiple anthropogenic disturbances, including capture fisheries and aquaculture. Ignoring possible interactions between multiple disturbances may cause serious consequences in our understanding of ecosystem dynamics. This study simulates individual and combined effects of fishing activities and shellfish cultivation on a semi-closed bay ecosystem using Ecopath with Ecosim (EwE). The changes of biomass and ecosystem structure were examined for three scenarios of having fishing alone, shellfish cultivation alone and both fishing and aquaculture. We found considerable impacts of shellfish aquaculture but minor impacts from fishing, suggesting shellfish aquaculture had dominated impacts on the study ecosystem. In addition, the effects of fishing and shellfish aquaculture were not additive on species biomass, rather showing a combined effect with synergy. Given the same loss in fisheries yield, controlling fishing and shellfish aquaculture simultaneously was more efficient for increasing nekton biomass compared to the control of either activity. We highlight the necessity for integrating management of multiple human stressors for an ecosystem-based management.

Impact of Geomorphological Changes to Harbor Resonance During Meteotsunamis: The Vela Luka Bay Test Case

NASA Astrophysics Data System (ADS)

Denamiel, Cléa; Šepić, Jadranka; Vilibić, Ivica

2018-05-01

In engineering studies, harbor resonance, including quality and amplification factors, is typically computed for swell and waves with periods shorter than 10 min. However, in various locations around the world, such as Vela Luka Bay in Croatia, meteotsunami waves of periods greater than 10 min can excite the bay or harbor natural modes and produce substantial structural damages. In this theoretical study, the impact of some geomorphological changes of Vela Luka Bay—i.e. deepening of the bay, dredging the harbor, adding a pier or a marina—to the amplification of the meteotsunami waves are presented for a set of 6401 idealized pressure wave field forcing used to derive robust statistics. The most substantial increase in maximum elevation is found when the Vela Luka harbor is dredged to a 5 m depth, which is in contradiction with the calculation of the quality factor showing a decrease of the harbor natural resonance. It has been shown that the forcing energy content at different frequency bands should also be taken into account when estimating the quality and amplification factors, as their typical definitions derived from the peak frequency of the sea level spectrum fail to represent the harbor response during meteotsunami events. New definitions of these factors are proposed in this study and are shown to be in good agreement with the results of the statistical analysis of the Vela Luka Bay maximum elevation results. In addition, the presented methodology can easily be applicable to any other location in the world where meteotsunamis occur.

Assessing the impacts of climate change on discharge and nutrient losses from a karstic agricultural sub-basin in the Upper Chesapeake Bay watershed

USDA-ARS?s Scientific Manuscript database

The health of the Chesapeake Bay Basin ecosystem, which lies within the heavily populated Northeastern United States, relies on reducing nutrient loading to the Chesapeake Bay by the 2025 TMDL deadline and on into the future. Doing so requires evaluating the impact of current agricultural management...

Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure

USGS Publications Warehouse

Self-Trail, Jean M.; Edwards, Lucy E.; Litwin, Ronald J.

2009-01-01

Biostratigraphic analysis of sedimentary breccias and diamictons in the Chesapeake Bay impact structure provides information regarding the timing and processes of late-stage gravitational crater collapse and ocean resurge. Studies of calcareous nannofossil and palynomorph assemblages in the International Continental Scientific Drilling Program (ICDP)–U.S. Geological Survey (USGS) Eyreville A and B cores show the mixed-age, mixed-preservation microfossil assemblages that are typical of deposits from the upper part of the Chesapeake Bay impact structure. Sparse, poorly preserved, possibly thermally altered pollen is present within a gravelly sand interval below the granite slab at 1392 m in Eyreville core B, an interval that is otherwise barren of calcareous nannofossils and dinocysts. Gravitational collapse of water- saturated sediments from the transient crater wall resulted in the deposition of sediment clasts primarily derived from the nonmarine Cretaceous Potomac Formation. Collapse occurred before the arrival of resurge. Low pollen Thermal Alteration Index (TAI) values suggest that these sediments were not thermally altered by contact with the melt sheet. The arrival of resurge sedimentation is identified based on the presence of diamicton zones and stringers rich in glauconite and marine microfossils at 866.7 m. This horizon can be traced across the crater and can be used to identify gravitational collapse versus ocean-resurge sedimentation. Glauconitic quartz sand diamicton dominates the sediments above 618.2 m. Calcareous nannofossil and dino-flagellate data from this interval suggest that the earliest arriving resurge from the west contained little or no Cretaceous marine input, but later resurge pulses mined Cretaceous sediments east of the Watkins core in the annular trough. Additionally, the increased distance traveled by resurge to the central crater in turbulent flow conditions resulted in the disaggregation of Paleogene unconsolidated sediments. As a result, intact Paleogene clasts in Eyreville cores are rare, but clasts of semilithified Potomac Formation silts and clays are common.

Paleontological interpretations of crater processes and infilling of synimpact sediments from the Chesapeake Bay impact structure

USGS Publications Warehouse

,; Edwards, L.E.; Litwin, R.J.

2009-01-01

Biostratigraphic analysis of sedimentary breccias and diamictons in the Chesapeake Bay impact structure provides information regarding the timing and processes of late-stage gravitational crater collapse and ocean resurge. Studies of calcareous nannofossil and palynomorph assemblages in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville A and B cores show the mixed-age, mixed-preservation microfossil assemblages that are typical of deposits from the upper part of the Chesapeake Bay impact structure. Sparse, poorly preserved, possibly thermally altered pollen is present within a gravelly sand interval below the granite slab at 1392 m in Eyreville core B, an interval that is otherwise barren of calcareous nannofossils and dinocysts. Gravitational collapse of watersaturated sediments from the transient crater wall resulted in the deposition of sediment clasts primarily derived from the nonmarine Cretaceous Potomac Formation. Collapse occurred before the arrival of resurge. Low pollen Thermal Alteration Index (TAI) values suggest that these sediments were not thermally altered by contact with the melt sheet. The arrival of resurge sedimentation is identified based on the presence of diamicton zones and stringers rich in glauconite and marine microfossils at 866.7 m. This horizon can be traced across the crater and can be used to identify gravitational collapse versus ocean-resurge sedimentation. Glauconitic quartz sand diamicton dominates the sediments above 618.2 m. Calcareous nannofossil and dinoflagellate data from this interval suggest that the earliest arriving resurge from the west contained little or no Cretaceous marine input, but later resurge pulses mined Cretaceous sediments east of the Watkins core in the annular trough. Additionally, the increased distance traveled by resurge to the central crater in turbulent flow conditions resulted in the disaggregation of Paleogene unconsolidated sediments. As a result, intact Paleogene clasts in Eyreville cores are rare, but clasts of semilithified Potomac Formation silts and clays are common. ?? 2009 The Geological Society of America.

CALCULATED MOLECULAR STRUCTURES AND POTENTIAL ENERGY FUNCTIONS OF PAHS WITH METHYL CROWDING IN THE BAY REGION AND THEIR METABOLITES: COMPARISON TO EXPERIMENTAL STRUCTURES

EPA Science Inventory

Calculated molecular structures and potential energy functions ofP AHs with methyl crowding in the bay region and their metabolites: Comparison to experimental structures

PAHs with methyl group substitution near a bay region represent a class of chemicals associated with ...

CALCULATED MOLECULAR STRUCTURES AND POTENTIAL ENERGY FUNCTIONS OF PAHS WITH METHYL CROWDING IN THE BAY REGION AND THEIR METABOLITES: COMPARISON TO EXPERIMENTAL STRUCTURES

EPA Science Inventory

Abstract Title: Calculated molecular structures and potential energy functions of P AHs with methyl crowding in the bay region and their metabolites: Comparison to experimental structures.

Abstract:
PAHs with methyl group substitution near a bay region represent a cl...

High Energy Wide Area Blunt Impact on Composite Aircraft Structures

NASA Astrophysics Data System (ADS)

DeFrancisci, Gabriela K.

The largest source of damage to commercial aircraft is caused by accidental contact with ground service equipment (GSE). The cylindrical bumper typically found on GSE distributes the impact load over a large contact area, possibly spanning multiple internal structural elements (frame bays) of a stiffened-skin fuselage. This type of impact can lead to damage that is widespread and difficult to detect visually. To address this problem, monolithic composite panels of various size and complexity have been modeled and tested quasi-statically and dynamically. The experimental observations have established that detectability is dependent on the impact location and immediately-adjacent internal structure of the panel, as well as the impactor geometry and total deformation of the panel. A methodology to model and predict damage caused by wide area blunt impact events was established, which was then applied to more general cases that were not tested in order to better understand the nature of this type of impact event and how it relates to the final damage state and visual detectability.

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.

Ammonia-oxidizing bacteria and archaea in wastewater treatment plant sludge and nearby coastal sediment in an industrial area in China.

PubMed

Zhang, Yan; Chen, Lujun; Sun, Renhua; Dai, Tianjiao; Tian, Jinping; Wen, Donghui

2015-05-01

Under the increasing pressure of human activities, Hangzhou Bay has become one of the most seriously polluted waters along China's coast. Considering the excessive inorganic nitrogen detected in the bay, in this study, the impact of an effluent from a coastal industrial park on ammonia-oxidizing microorganisms (AOMs) of the receiving area was interpreted for the first time by molecular technologies. Revealed by real-time PCR, the ratio of archaeal amoA/bacterial amoA ranged from 5.68 × 10(-6) to 4.79 × 10(-5) in the activated sludge from two wastewater treatment plants (WWTPs) and 0.54-3.44 in the sediments from the effluent receiving coastal area. Analyzed by clone and pyrosequencing libraries, genus Nitrosomonas was the predominant ammonia-oxidizing bacteria (AOB), but no ammonia-oxidizing archaea (AOA) was abundant enough for sequencing in the activated sludge from the WWTPs; genus Nitrosomonas and Nitrosopumilus were the dominant AOB and AOA, respectively, in the coastal sediments. The different abundance of AOA but similar structure of AOB between the WWTPs and nearby coastal area probably indicated an anthropogenic impact on the microbial ecology in Hangzhou Bay.

Assessing net community production in a glaciated Alaskan fjord

NASA Astrophysics Data System (ADS)

Reisdorph, S. C.; Mathis, J. T.

2015-09-01

The impact of deglaciation in Glacier Bay has been observed to seasonally influence the biogeochemistry of this marine system. The influence from surrounding glaciers, particularly tidewater glaciers, has the potential to affect the efficiency and structure of the marine food web within Glacier Bay. To assess the magnitude and the spatial and temporal variability in net community production in a glaciated fjord, we measured dissolved inorganic carbon, inorganic macronutrients, dissolved oxygen, and particulate organic carbon between July 2011 and July 2012 in Glacier Bay, Alaska. High net community production rates were observed across the bay (~ 54 to ~ 81 mmol C m-2 d-1) between the summer and fall of 2011. However, between the fall and winter, as well as between the winter and spring of 2012, air-sea fluxes of carbon dioxide and organic matter respiration made net community production rates negative across most of the bay as inorganic carbon and macronutrient concentrations returned to pre-bloom levels. The highest organic carbon production occurred within the west arm between the summer and fall of 2011 with ~ 4.5 × 105 kg C d-1. Bay-wide, there was carbon production of ~ 9.2 × 105 g C d-1 between the summer and fall. Respiration and air-sea gas exchange were the dominant drivers of carbon chemistry between the fall and winter of 2012. The substantial spatial and temporal variability in our net community production estimates may reflect glacial influences within the bay, as meltwater is depleted in macronutrients relative to marine waters entering from the Gulf of Alaska in the middle and lower parts of the bay. Further glacial retreat will likely lead to additional modifications in the carbon biogeochemistry of Glacier Bay, with unknown consequences for the local marine food web, which includes many species of marine mammals.

Anatomy of the Chesapeake Bay impact structure revealed by seismic imaging, Delmarva Peninsula, Virginia, USA

USGS Publications Warehouse

Catchings, R.D.; Powars, D.S.; Gohn, G.S.; Horton, J. Wright; Goldman, M.R.; Hole, J.A.

2008-01-01

A 30-km-long, radial seismic reflection and refraction survey completed across the northern part of the late Eocene Chesapeake Bay impact structure (CBIS) on the Delmarva Peninsula, Virginia, USA, confirms that the CBIS is a complex central-peak crater. We used a tomographic P wave velocity model and low-fold reflection images, constrained by data from two deep boreholes located on the profile, to interpret the structure and composition of the upper 5 km of crust. The seismic images exhibit well-defined structural features, including (with increasing radial distance) a collapsed central uplift, a breccia-filled moat, and a collapsed transient-crater margin (which collectively constitute a ???40-km-wide collapsed transient crater), and a shallowly deformed annular trough. These seismic images are the first to resolve the deep structure of the crater (>1 km) and the boundaries between the central uplift, moat, and annular trough. Several distinct seismic signatures distinguish breccia units from each other and from more coherent crystalline rocks below the central uplift, moat, and annular trough. Within the moat, breccia extends to a minimum depth of 1.5 km or a maximum of 3.5 km, depending upon the interpretation of the deepest layered materials. The images show ???350 to 500 m of postimpact sediments above the impactites. The imaged structure of the CBIS indicates a complex sequence of event during the cratering process that will provide new constraints for numerical modeling. Copyright 2008 by the American Geophysical Union.

The competing impacts of climate change and nutrient reductions on dissolved oxygen in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Irby, Isaac D.; Friedrichs, Marjorie A. M.; Da, Fei; Hinson, Kyle E.

2018-05-01

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 level will increase estuarine circulation, reducing residence time in bottom waters and increasing stratification. As a result, oxygen concentrations in bottom waters are projected to increase, while oxygen concentrations at mid-depths (3 < DO < 5 mg L-1) will typically decrease. Changes in precipitation are projected to deliver higher winter and spring freshwater flow and nutrient loads, fueling increased primary production. Together, these multiple climate impacts will lower DO throughout the Chesapeake Bay and negatively impact progress towards meeting water quality standards associated with the Chesapeake Bay Total Maximum Daily Load. However, this research also shows that the potential impacts of climate change will be significantly smaller than improvements in DO expected in response to the required nutrient reductions, especially at the anoxic and hypoxic levels. Overall, increased temperature exhibits the strongest control on the change in future DO concentrations, primarily due to decreased solubility, while sea level rise is expected to exert a small positive impact and increased winter river flow is anticipated to exert a small negative impact.

The Eocene-Oligocene sedimentary record in the Chesapeake Bay impact structure: Implications for climate and sea-level changes on the western Atlantic margin

USGS Publications Warehouse

Schulte, P.; Wade, B.S.; Kontny, A.; ,

2009-01-01

A multidisciplinary investigation of the Eocene-Oligocene transition in the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville core from the Chesapeake Bay impact basin was conducted in order to document environmental changes and sequence stratigraphic setting. Planktonic foraminifera and calcareous nannofossil biostratigraphy indicate that the Eyreville core includes an expanded upper Eocene (Biozones E15 to E16 and NP19/20 to NP21, respectively) and a condensed Oligocene-Miocene (NP24-NN1) sedimentary sequence. The Eocene-Oligocene contact corresponds to a =3-Ma-long hiatus. Eocene- Oligocene sedimentation is dominated by great diversity and varying amounts of detrital and authigenic minerals. Four sedimentary intervals are identified by lithology and mineral content: (1) A 30-m-thick, smectite- and illite-rich interval directly overlies the Exmore Formation, suggesting long-term reworking of impact debris within the Chesapeake Bay impact structure. (2) Subsequently, an increase in kaolinite content suggests erosion from soils developed during late Eocene warm and humid climate in agreement with data derived from other Atlantic sites. However, the kaolinite increase may also be explained by change to a predominant sediment input from outside the Chesapeake Bay impact structure caused by progradation of more proximal facies belts during the highstand systems tract of the late Eocene sequence E10.Spectral analysis based on gamma-ray and magnetic susceptibility logs suggests infl uence of 1.2 Ma low-amplitude oscillation of the obliquity period during the late Eocene. (3) During the latest Eocene (Biozones NP21 and E16), several lithological contacts (clay to clayey silt) occur concomitant with a prominent change in the mineralogical composition with illite as a major component: This lithological change starts close to the Biozone NP19/20-NP21 boundary and may correspond to sequence boundary E10-E11 as observed in other northwest Atlantic margin sections. It could result from a shift to more distal depositional environments and condensed sedimentation during maximum fl ooding, rather than refl ecting a climatic change in the hinterland. The distinct 1% increase of the oxygen isotopes may correspond to the short-term latest Eocene "precursor isotope event." (4) The abrupt increase of sediment grainsize, carbonate content, and abundance of authigenic minerals (glauconite) across the major unconformity that separates Eocene from Oligocene sediments in the Eyreville core refl ects deposition in shallower settings associated with erosion, winnowing, and reworking. Sediments within the central crater were affected by the rapid eustatic sea-level changes associated with the greenhouse-icehouse transition, as well as by an abrupt major uplift event and possibly enhanced current activity on the northwestern Atlantic margin. ?? 2009 The Geological Society of America.

Diagnosis of potential stressors adversely affecting benthic invertebrate communities in Greenwich Bay, Rhode Island, USA

EPA Science Inventory

Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was imp...

Insights into Seasonal Variations in Phosphorus Concentrations and Cycling in Monterey Bay

NASA Astrophysics Data System (ADS)

Kong, M.; Defforey, D.; Paytan, A.; Roberts, K.

2014-12-01

Phosphorus (P) is an essential nutrient for life as it is a structural constituent in many cell components and a key player in cellular energy metabolism. Therefore, P availability can impact primary productivity. Here we quantify dissolved and particulate P compounds and trace P sources and cycling in Monterey Bay over the course of a year. This time series gives insights into monthly and seasonal variations in the surface water chemistry of this region. Preliminary characterization of seawater samples involves measuring total P and soluble reactive P (SRP) concentrations. 31P nuclear magnetic resonance spectroscopy (31P NMR) is used to determine the chemical structure of organic phosphorus compounds present in surface seawater. The isotopic signature of phosphatic oxygen (δ18Op) is used as a proxy for studying P cycling and sources. Oxygen isotope ratios in phosphate are determined by continuous-flow isotope mass ratio spectrometry (CF-IRMS) following purification of dissolved P from seawater samples and precipitation as silver phosphate. We expect to observe seasonal changes in P concentrations, as well as differences in organic P composition and P sources. The chemical structure of organic P compounds will affect their bioavailability and thus the extent to which they can fuel primary productivity in Monterey Bay. δ18Op will reflect source signatures and provide information on turnover rates of P in surface waters. Results from this work will provide valuable insights into seasonal changes in P cycling in surface waters and have important implications for understanding primary productivity in the Monterey Bay ecosystem.

Forecasting the future of coast live oak forests in the face of sudden oak death

Treesearch

Letty B. Brown; Barbara Allen-Diaz

2006-01-01

Little is known about the potential short- and long-term impacts of sudden oak death (SOD) on forest structure and composition. This study began in 2002 to evaluate the effects of SOD on coast live oak (Quercus agrifolia) - California bay laurel (Umbellularia californica) forests over a gradient of Phytophthora ramorum...

Environmental Shaping of Sponge Associated Archaeal Communities

PubMed Central

Turque, Aline S.; Batista, Daniela; Silveira, Cynthia B.; Cardoso, Alexander M.; Vieira, Ricardo P.; Moraes, Fernando C.; Clementino, Maysa M.; Albano, Rodolpho M.; Paranhos, Rodolfo; Martins, Orlando B.; Muricy, Guilherme

2010-01-01

Background Archaea are ubiquitous symbionts of marine sponges but their ecological roles and the influence of environmental factors on these associations are still poorly understood. Methodology/Principal Findings We compared the diversity and composition of archaea associated with seawater and with the sponges Hymeniacidon heliophila, Paraleucilla magna and Petromica citrina in two distinct environments: Guanabara Bay, a highly impacted estuary in Rio de Janeiro, Brazil, and the nearby Cagarras Archipelago. For this we used metagenomic analyses of 16S rRNA and ammonia monooxygenase (amoA) gene libraries. Hymeniacidon heliophila was more abundant inside the bay, while P. magna was more abundant outside and P. citrina was only recorded at the Cagarras Archipelago. Principal Component Analysis plots (PCA) generated using pairwise unweighted UniFrac distances showed that the archaeal community structure of inner bay seawater and sponges was different from that of coastal Cagarras Archipelago. Rarefaction analyses showed that inner bay archaeaoplankton were more diverse than those from the Cagarras Archipelago. Only members of Crenarchaeota were found in sponge libraries, while in seawater both Crenarchaeota and Euryarchaeota were observed. Although most amoA archaeal genes detected in this study seem to be novel, some clones were affiliated to known ammonia oxidizers such as Nitrosopumilus maritimus and Cenarchaeum symbiosum. Conclusion/Significance The composition and diversity of archaeal communities associated with pollution-tolerant sponge species can change in a range of few kilometers, probably influenced by eutrophication. The presence of archaeal amoA genes in Porifera suggests that Archaea are involved in the nitrogen cycle within the sponge holobiont, possibly increasing its resistance to anthropogenic impacts. The higher diversity of Crenarchaeota in the polluted area suggests that some marine sponges are able to change the composition of their associated archaeal communities, thereby improving their fitness in impacted environments. PMID:21209889

Microbial biogeography of San Francisco Bay sediments

NASA Astrophysics Data System (ADS)

Lee, J. A.; Francis, C. A.

2014-12-01

The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess whether patterns of diversity observed at the broadest of taxonomic scales also apply to patterns observed within a single extremely diverse gene (nirS). In sum, this project provides a first look at the forces driving the migration and selection of microbial communities in San Francisco Bay.

Seafloor Structural Geomorphic Evolution in Response to Seamount Subduction, Poverty Bay Indentation, New Zealand

NASA Astrophysics Data System (ADS)

Bodger, K. L.; Pettinga, J. R.; Barnes, P. M.

2006-12-01

More than 4000 km2 of high quality bathymetric and backscatter imaging of the Poverty Bay Indentation across the northern part of the Hikurangi subduction zone provide new insights into the relationship between seafloor morphology and active structures. The swath bathymetry extends from the edge of the continental shelf to the abyssal plain, at depths of between 100 to 3500 metres. The origin of the slope re-entrant is inferred to be related to multiple seamount impacts, and these collisions have initiated numerous large-scale gravitational collapse structures, multiple debris flow and avalanche deposits, which range in down-slope length from a few hundred metres to more than 40 km. The Poverty Bay Indentation has been simultaneously eroded by canyon systems that exhibit many of the features of incised river systems onshore. The swath images are complemented by the availability of excellent high-quality processed multi-channel seismic reflection data, single channel high-resolution 3.5 kHz seismic reflection data, as well as a limited number of core samples. Seismic reflection profiles and seafloor morphology are used to provide three morpho-structural sections. The comparison of these sections highlights the different effects of seamount subduction on the evolution of the margin and the re-entrant. The northern two sections are located to the north side of the re-entrant and reveal the role of seamount impact on the interrelationship between the structural evolution with respect to seafloor morphology. Here the development of an over-steepened margin with fault reactivation, inversion and over- printing leads to very complex structural styles of deformation and geometry in both seismic reflection profiles and seafloor morphology. There is evidence of an older, inactive thrust front buried beneath the upper and mid- slope basins. Beneath the mid-slope a subducted seamount is revealed by the presence of relief on the subduction interface and associated structural complexity in the over-riding wedge. The Poverty Bay canyon represents a structural transition zone coinciding with the re-entrant. The accretionary slope south of the re- entrant conforms more closely to the classic accretionary slope style of deformation. Backthrusts in this section propagate from a much shallower level than in the northern sections. Inversion is commonly observed in the mid slope and continental shelf basins, particularly to the south. Initial interpretations indicate that: i) seamount impact significantly influences the structural evolution, and submarine geomorphology of the inboard slope of the Hikurangi subduction zone, including the generation of large-scale gravitational collapse features; ii) the large gully systems located at the upper shelf slope boundary represent the most likely source areas for the multiple mega debris flows recognised from seafloor morphology and in seismic sections; iii) there exists a complex interaction between the evolving thrust-driven submarine ridges, ponded slope basins and the structural geometry and evolution of the near-surface fault zones (imbrication); iv) the submarine canyons may initiate complex patterns of fault zone segmentation and displacement transfer within the accretionary slope; and v) seamount subduction and subsequent instability of the margin may directly result in tsunami generation.

Assessing polar bear (Ursus maritimus) population structure in the Hudson Bay region using SNPs.

PubMed

Viengkone, Michelle; Derocher, Andrew Edward; Richardson, Evan Shaun; Malenfant, René Michael; Miller, Joshua Moses; Obbard, Martyn E; Dyck, Markus G; Lunn, Nick J; Sahanatien, Vicki; Davis, Corey S

2016-12-01

Defining subpopulations using genetics has traditionally used data from microsatellite markers to investigate population structure; however, single-nucleotide polymorphisms (SNPs) have emerged as a tool for detection of fine-scale structure. In Hudson Bay, Canada, three polar bear ( Ursus maritimus ) subpopulations (Foxe Basin (FB), Southern Hudson Bay (SH), and Western Hudson Bay (WH)) have been delineated based on mark-recapture studies, radiotelemetry and satellite telemetry, return of marked animals in the subsistence harvest, and population genetics using microsatellites. We used SNPs to detect fine-scale population structure in polar bears from the Hudson Bay region and compared our results to the current designations using 414 individuals genotyped at 2,603 SNPs. Analyses based on discriminant analysis of principal components (DAPC) and STRUCTURE support the presence of four genetic clusters: (i) Western-including individuals sampled in WH, SH (excluding Akimiski Island in James Bay), and southern FB (south of Southampton Island); (ii) Northern-individuals sampled in northern FB (Baffin Island) and Davis Strait (DS) (Labrador coast); (iii) Southeast-individuals from SH (Akimiski Island in James Bay); and (iv) Northeast-individuals from DS (Baffin Island). Population structure differed from microsatellite studies and current management designations demonstrating the value of using SNPs for fine-scale population delineation in polar bears.

Structure, age and origin of the bay-mouth shoal deposits, Chesapeake Bay, Virginia

USGS Publications Warehouse

Colman, Steven M.; Berquist, C.R.; Hobbs, C. H.

1988-01-01

The mouth of Chesapeake Bay contains a distinctive shoal complex and related deposits that result from the complex interaction of three different processes: (1) progradation of a barrier spit at the southern end of the Delmarva Peninsula, (2) strong, reversing tidal currents that transport and rework sediment brought to the bay mouth from the north, and (3) landward (bayward) net non-tidal circulation and sediment transport. Together, these processes play a major role in changing the configuration of the estuary and filling it with sediment. The deposits at the mouth of the bay hold keys both to the evolution of the bay during the Holocene transgression and to the history of previous generations of the bay. The deposit associated with the shoals at the mouth of the bay, the bay-mouth sand, is a distinct stratigraphic unit composed mostly of uniform, gray, fine sand. The position and internal structure of the unit shows that it is related to near-present sea level, and thus is less than a few thousand years old. The processes affecting the upper surface of the deposit and the patterns of erosion and deposition at this surface are complex, but the geometry and structure of the deposit indicate that it is a coherent unit that is prograding bayward and tending to fill the estuary. The source of the bay-mouth sand is primarily outside the bay in the nearshore zone of the Delmarva Peninsula and on the inner continental shelf. The internal structure of the deposit, its surface morphology, its heavy-mineral composition, bottom-current studies, comparative bathymetry, and sediment budgets all suggest that sand is brought to the bay mouth by southerly longshore drift along the Delmarva Peninsula and then swept into the bay. In addition to building the southward- and bayward-prograding bay-mouth sand, these processes result in sand deposition tens of kilometers into the bay. ?? 1988.

Some risk factors that affect contamination of mussels (Mytilus galloprovincialis) from the Bay of Kotor, Montenegro

NASA Astrophysics Data System (ADS)

Grković, N.; Velebit, B.; Teodorović, V.; Karabasil, N.; Vasilev, D.; Đorđević, V.; Dimitrijević, M.

2017-09-01

Pollution and contamination of the Bay of Kotor ecosystem arise from both anthropogenic sources and natural weathering. In recent decades, a need has arisen for regular control of marine organisms, which are used in human nutrition, because the entire bay is constantly and increasingly exposed to negative anthropogenic impact. Molluscs, including mussels (Mytilus galloprovincialis), can be involved in foodborne disease. They are filter feeding organisms, able to retain and concentrate in their bodies the bacteria, parasites, viruses and biotoxins of marine algae present in their external environment. A structured field study was undertaken in the Bay of Kotor, Montenegro, in order to investigate plausible influence of environmental factors, like rainfall and temperature, on the variability of Escherichia coli and norovirus (NoV). This study focuses on human-derived pathogens that are abundant in sewage-related sources. We proved the negative correlation between outside temperature and the number of E.coli and the presents of Norovirus in Bay of Kotor mussel. We used this data from the sampling site to discuss options to better manage the risk of contamination of shellfish. From the aspect of food safety, an upgrade of monitoring plans in the future could lead to obtaining safer products.

Density-stratified flow events in Great Salt Lake, Utah, USA: implications for mercury and salinity cycling

USGS Publications Warehouse

Naftz, David L.; Carling, Gregory T.; Angeroth, Cory; Freeman, Michael; Rowland, Ryan; Pazmiño, Eddy

2014-01-01

Density stratification in saline and hypersaline water bodies from throughout the world can have large impacts on the internal cycling and loading of salinity, nutrients, and trace elements. High temporal resolution hydroacoustic and physical/chemical data were collected at two sites in Great Salt Lake (GSL), a saline lake in the western USA, to understand how density stratification may influence salinity and mercury (Hg) distributions. The first study site was in a causeway breach where saline water from GSL exchanges with less saline water from a flow restricted bay. Near-surface-specific conductance values measured in water at the breach displayed a good relationship with both flow and wind direction. No diurnal variations in the concentration of dissolved (total and MeHg loadings was observed during periods of elevated salinity. The second study site was located on the bottom of GSL where movement of a high-salinity water layer, referred to as the deep brine layer (DBL), is restricted to a naturally occurring 1.5-km-wide “spillway” structure. During selected time periods in April/May, 2012, wind-induced flow reversals in a railroad causeway breach, separating Gunnison and Gilbert Bays, were coupled with high-velocity flow pulses (up to 55 cm/s) in the DBL at the spillway site. These flow pulses were likely driven by a pressure response of highly saline water from Gunnison Bay flowing into the north basin of Gilbert Bay. Short-term flow reversal events measured at the railroad causeway breach have the ability to move measurable amounts of salt and Hg from Gunnison Bay into the DBL. Future disturbance to the steady state conditions currently imposed by the railroad causeway infrastructure could result in changes to the existing chemical balance between Gunnison and Gilbert Bays. Monitoring instruments were installed at six additional sites in the DBL during October 2012 to assess impacts from any future modifications to the railroad causeway.

An ecological assessment of land use impacts in small watersheds of the Chesapeake Bay

Treesearch

Andrew Leight; John Jacobs; Lonnie Gonsalves; Gretchen Messick; Shawn McLaughlin; Jay Lewis; Juliana Brush; Eric Daniels; Matthew Rhodes; Lewis Collier; Robert Wood

2016-01-01

The Chesapeake Bay, the nation’s largest estuary, remains in relatively poor condition despite intensive public and scientific attention. In order to better understand the stressors and impacts occurring in the Bay as a result of land management decisions we conducted an assessment of both habitat condition and organismal response in three small watersheds of the upper...

18. DETAIL VIEW OF THE HIGH BAY STRUCTURAL SYSTEM AND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. DETAIL VIEW OF THE HIGH BAY STRUCTURAL SYSTEM AND WINDOW ILLUMINATION AT THE SHRINK PIT AREA, S END OF B BAY; LOOKING SSE. (Ceronie) - Watervliet Arsenal, Building No. 135, Gillespie Road, South of Parker Road, Watervliet, Albany County, NY

Tampa Bay as a model estuary for examining the impact of human activities on biogeochemical processes: an introduction

USGS Publications Warehouse

Swarzenski, Peter W.; Baskaran, Mark; Henderson, Carl S.; Yates, Kim

2007-01-01

Tampa Bay is a shallow, Y-shaped coastal embayment that is located along the center of the Florida Platform – an expansive accumulation of Cretaceous–Tertiary shallow-water carbonates and evaporites that were periodically exposed during glacio–eustatic sea level fluctuations. As a consequence, extensive karstification likely had a controlling impact on the geologic evolution of Tampa Bay. Despite its large aerial size (∼ 1000 km2), Tampa Bay is relatively shallow (mean depth = 4 m) and its watershed (6700 km2) is among the smallest in the Gulf of Mexico. About 85% of all freshwater inflow (mean = 63 m3 s-1) to the bay is carried by four principal tributaries (Orlando et al., 1993). Groundwater makes up an important component of baseflow of these coastal streams and may also be important in delivering nutrients and other constituents to the bay proper by submarine groundwater discharge.

[Atmospheric depositions of biogenic elements and their ecological effects on marine ecosystem of Jiaozhou Bay: A review].

PubMed

Xing, Jian Wei; Song, Jin Ming; Yuan, Hua Mao; Li, Xue Gang; Li, Ning; Duan, Li Qin; Qu, Bao Xiao; Kang, Xu Ming

2017-01-01

As a typical semi-closed bay, Jiaozhou Bay, is remarkably affected by human activities. Biogenic elements transported into the oceans by the atmospheric deposition of anthropogenic particles can lead to profound impacts on the ecosystem of Jiaozhou Bay. In this paper, the researches of atmospheric dry and wet depositions in the Jiaozhou Bay were systematically summarized from the following three aspects: study methods, variation characteristics of the fluxes and their influencing factors and the ecological effects of atmospheric deposition. The concentrations and fluxes of nitrogen species in atmospheric dry and wet depositions were very high in the Jiaozhou Bay compared with other bays, estuaries and marginal seas around the world. The dissolved inorganic nitrogen (DIN) was the main component of the total dissolved nitrogen (TDN) and the dissolved organic nitrogen (DON) accounted for 22%-31% of TDN. However, the concentrations and fluxes of phosphate and silicate species were very low. The atmospheric deposition fluxes of (NO 3 - -N+NO 2 - -N) were slightly higher than terrestrial inputs, while the fluxes of NH 4 + -N, PO 4 3- -P and SiO 3 2- -Si were very low compared with terrestrial inputs. The concentration of total suspended particulates (TSP) in the air, the intensity of the emission sources, precipitation amount and meteorological conditions are the major factors influencing the atmospheric depositions of biogenic elements, which can increase the primary productivity, change the structure of nutrients and the structure of phytoplankton communities in surface seawater and further promote the succession of phytoplankton dominant species from diatom to dinoflagellate in the Jiaozhou Bay. On that basis, the future research should be focused on constructing the monitoring network for atmospheric dry and wet depositions, accurately quantifying the deposition rates of aerosol particles of different forms and sizes, recognizing the ecological effects and biogeochemical mechanisms of atmospheric depositions of biogenic elements and discriminating the mechanisms, fluxes and influencing factors of atmospheric deposition biogenic elements via indirect approaches such as overland runoff, sheetflood and permeation etc. It is significant for illuminating the effects of anthropogenic activities on the coastal waters as well as understanding the bio-geochemical processes of biogenic elements in marginal seas by elucidating atmospheric depositions of biogenic elements in the Jiaozhou Bay.

Deployable geodesic truss structure

NASA Technical Reports Server (NTRS)

Mikulas, Martin M., Jr. (Inventor); Rhodes, Marvin D. (Inventor); Simonton, J. Wayne (Inventor)

1987-01-01

A deployable geodesic truss structure which can be deployed from a stowed state to an erected state is described. The truss structure includes a series of bays, each bay having sets of battens connected by longitudinal cross members which give the bay its axial and torsional stiffness. The cross members are hinged at their mid point by a joint so that the cross members are foldable for deployment or collapsing. The bays are deployed and stabilized by actuator means connected between the mid point joints of the cross members. Hinged longerons may be provided to also connect the sets of battens and to collapse for stowing with the rest of the truss structure.

A Coastal Bay Summer Breeze Study, Part 2: High-resolution Numerical Simulation of Sea-breeze Local Influences

NASA Astrophysics Data System (ADS)

Calmet, Isabelle; Mestayer, Patrice G.; van Eijk, Alexander M. J.; Herlédant, Olivier

2018-04-01

We complete the analysis of the data obtained during the experimental campaign around the semi circular bay of Quiberon, France, during two weeks in June 2006 (see Part 1). A reanalysis of numerical simulations performed with the Advanced Regional Prediction System model is presented. Three nested computational domains with increasing horizontal resolution down to 100 m, and a vertical resolution of 10 m at the lowest level, are used to reproduce the local-scale variations of the breeze close to the water surface of the bay. The Weather Research and Forecasting mesoscale model is used to assimilate the meteorological data. Comparisons of the simulations with the experimental data obtained at three sites reveal a good agreement of the flow over the bay and around the Quiberon peninsula during the daytime periods of sea-breeze development and weakening. In conditions of offshore synoptic flow, the simulations demonstrate that the semi-circular shape of the bay induces a corresponding circular shape in the offshore zones of stagnant flow preceding the sea-breeze onset, which move further offshore thereafter. The higher-resolution simulations are successful in reproducing the small-scale impacts of the peninsula and local coasts (breeze deviations, wakes, flow divergences), and in demonstrating the complexity of the breeze fields close to the surface over the bay. Our reanalysis also provides guidance for numerical simulation strategies for analyzing the structure and evolution of the near-surface breeze over a semi-circular bay, and for forecasting important flow details for use in upcoming sailing competitions.

Field Evaluation of Four Novel Roof Designs for Energy-Efficient Manufactured Homes

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

Levy, E.; Dentz, J.; Ansanelli, E.

2015-12-03

"9A five-bay roof test structure was built, instrumented and monitored in an effort to determine through field testing and analysis the relative contributions of select technologies toward reducing energy use in new manufactured homes. The roof structure in Jamestown, California was designed to examine how differences in roof construction impact space conditioning loads, wood moisture content and attic humidity levels. Conclusions are drawn from the data on the relative energy and moisture performance of various configurations of vented and sealed attics.

Field Evaluation of Four Novel Roof Designs for Energy-Efficient Manufactured Homes

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

Levy, E.; Dentz, J.; Ansanelli, E.

2015-12-01

A five-bay roof test structure was built, instrumented and monitored in an effort to determine through field testing and analysis the relative contributions of select technologies toward reducing energy use in new manufactured homes. The roof structure in Jamestown, California was designed to examine how differences in roof construction impact space conditioning loads, wood moisture content and attic humidity levels. Conclusions are drawn from the data on the relative energy and moisture performance of various configurations of vented and sealed attics.

Assessment of gonadal and thyroid histology in Gulf killifish (Fundulus grandis) from Barataria Bay Louisiana one year after the Deepwater Horizon oil spill.

PubMed

Carr, Deborah L; Smith, Ernest E; Thiyagarajah, Arunthavarani; Cromie, Meghan; Crumly, Christopher; Davis, Angela; Dong, Meijun; Garcia, Carlos; Heintzman, Lucas; Hopper, Tiffany; Kouth, Kourtney; Morris, Kimberly; Ruehlen, Amelia; Snodgrass, Phillip; Vaughn, Katelynn; Carr, James A

2018-06-15

We examined gonads and thyroid glands of Gulf killifish (Fundulus grandis) 1yr after the Deepwater Horizon oil spill. F. grandis were trapped from two impacted sites in Barataria Bay (Bayou St. Denis, Bay Jimmy) and an un-impacted site in East Texas (Sabine Pass). The greatest number of F. grandis were collected at Sabine Pass. F. grandis collected at Bayou St. Denis were smaller and had smaller Fulton condition factor scores than fish collected at Sabine Pass. Sex ratios were biased roughly 2:1 in favor of females at Sabine Pass and Bayou St. Denis. Gonad-somatic index (GSI) in males from Sabine Pass was double that of fish from Bay Jimmy while germinal epithelium thickness of the testes was 2.7 fold smaller in males from the impacted site. GSI and oocyte diameters in females from Bayou St. Denis were significantly smaller than females from Bay Jimmy or the reference site. There were no differences in thyroid follicle cell height. While total polyaromatic hydrocarbons at the impacted sites were no different from the reference site, the impacted sites did have greater concentrations of benzo[a]pyrene in sediment pore water. The finding of smaller GSI and testicular germinal epithelium in males from an impacted site suggest that exposure to a combination of oil and dispersants may adversely impact testicular function. Copyright © 2018 Elsevier Inc. All rights reserved.

The impact of water loading on postglacial decay times in Hudson Bay

NASA Astrophysics Data System (ADS)

Han, Holly Kyeore; Gomez, Natalya

2018-05-01

Ongoing glacial isostatic adjustment (GIA) due to surface loading (ice and water) variations during the last glacial cycle has been contributing to sea-level changes globally throughout the Holocene, especially in regions like Canada that were heavily glaciated during the Last Glacial Maximum (LGM). The spatial and temporal distribution of GIA, as manifested in relative sea-level (RSL) change, are sensitive to the ice history and the rheological structure of the solid Earth, both of which are uncertain. It has been shown that RSL curves near the center of previously glaciated regions with no ongoing surface loading follow an exponential-like form, with the postglacial decay times associated with that form having a weak sensitivity to the details of the ice loading history. Postglacial decay time estimates thus provide a powerful datum for constraining the Earth's viscous structure and improving GIA predictions. We explore spatial patterns of postglacial decay time predictions in Hudson Bay by decomposing numerically modeled RSL changes into contributions from water and ice loading effects, and computing their relative impact on the decay times. We demonstrate that ice loading can contribute a strong geographic trend on the decay time estimates if the time window used to compute decay times includes periods that are temporally close to (i.e. contemporaneous with, or soon after) periods of active loading. This variability can be avoided by choosing a suitable starting point for the decay time window. However, more surprisingly, we show that across any adopted time window, water loading effects associated with inundation into, and postglacial flux out of, Hudson Bay and James Bay will impart significant geographic variability onto decay time estimates. We emphasize this issue by considering both maps of predicted decay times across the region and site-specific estimates, and we conclude that variability in observed decay times (whether based on existing or future data sets) may reflect this water loading signal.

76 FR 70480 - Otay River Estuary Restoration Project, South San Diego Bay Unit of the San Diego Bay National...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-14

... River Estuary Restoration Project, South San Diego Bay Unit of the San Diego Bay National Wildlife...), intend to prepare an environmental impact statement (EIS) for the proposed Otay River Estuary Restoration... any one of the following methods. Email: [email protected] . Please include ``Otay Estuary NOI'' in the...

Bristol Bay Assessment – Supplemental Peer Review Reports ...

EPA Pesticide Factsheets

These reports represent the results of independent peer reviews of several technical reports submitted to the public docket for the May 2012 draft of the Bristol Bay Assessment, An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska. Background In May 2012, the U.S. Environmental Protection Agency (USEPA) released the draft assessment entitled An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska, or the Bristol Bay Assessment. The purpose of the assessment is to provide a characterization of the biological and mineral resources of the Bristol Bay watershed, increase understanding of the potential impacts of large-scale mining on the region’s fish resources, and inform future governmental decisions. During the public comment period for the May 2012 draft, numerous technical reports were submitted to the public docket. The USEPA identified several of these reports as providing information about issues raised by the peer reviewers, but the reports did not show evidence of prior peer review. The USEPA made arrangements for a contractor to conduct independent peer reviews of seven such reports. The reports and the results of these supplemental peer reviews are provided here to document that the reports are of

Navy Aquatic Hazardous Waste Sites: The Problem and Possible Solutions

DTIC Science & Technology

1989-08-01

sensitive area. NEESA 13-013. Naval Weapons Station Concord , CA . This activity had 13 sites recommended for further study as having potential to impact the...also carry contaminants to the bay. NEESA 13-014. Naval Air Station Alameda, CA . Seven sites have the potential to impact San Francisco Bay. The West...addition, surface runoff may carry contaminants to the ponds or Kaneohe Bay. NEESA 13-040. Naval Weapons Station Charleston, SC. Four sites have the

San Francisco Bay Area Rapid Transit District (BART) climate change adaptation assessment pilot.

DOT National Transportation Integrated Search

2013-12-01

The objective of this pilot study was to evaluate the impacts of climate change on the San Francisco Bay Area Rapid Transit District : (BART) infrastructure and to develop and implement adaptation strategies against those impacts. Climate change haza...

River Flow Impacts Bacterial and Archaeal Community Structure in Surface Sediments in the Northern Gulf of Mexico.

PubMed

Ortmann, Alice C; Brannock, Pamela M; Wang, Lei; Halanych, Kenneth M

2018-04-17

Meiobenthic community structure in the northern Gulf of Mexico has been shown to be driven by geographical differences due to inshore-offshore gradients and location relative to river discharge. Samples collected along three transects spanning Mobile Bay, Alabama, showed significant differences in meiobenthic communities east of the bay compared to those sampled from the west. In contrast, analysis of bacterial and archaeal communities from the same sediment samples shows that the inshore-offshore gradient has minimal impact on their community structure. Significant differences in community structure were observed for Bacteria and Archaea between the east and west samples, but there was no difference in richness or diversity. Grouped by sediment type, higher richness was observed in silty samples compared to sandy samples. Significant differences were also observed among sediment types for community structure with bacteria communities in silty samples having more anaerobic sulfate reducers compared to aerobic heterotrophs, which had higher abundances in sandy sediments. This is likely due to increased organic matter in the silty sediments from the overlying river leading to low oxygen habitats. Most archaeal sequences represented poorly characterized high-level taxa, limiting interpretation of their distributions. Overlap between groups based on transect and sediment characteristics made determining which factor is more important in structuring bacterial and archaeal communities difficult. However, both factors are driven by discharge from the Mobile River. Although inshore-offshore gradients do not affect Bacteria or Archaea to the same extent as the meiobenthic communities, all three groups are strongly affected by sediment characteristics.

ESTUARINE HAZARD ASSESSMENT IN THE PENSACOLA BAY SYSTEM

EPA Science Inventory

ersonnel from the Gulf Ecology Division have conducted a multiyear evaluation of the environmental condition of areas in the Pensacola Bay System affected by point and nonpoint contamination. Areas of study included coastal rivers, residential canals, bayous and bays impacted by ...

Land- and sea-surface impacts on local coastal breezes

NASA Astrophysics Data System (ADS)

Veron, D. E.; Hughes, C.; Gilchrist, J.; Lodise, J.; Goldman, W.

2014-12-01

The state of Delaware has seen significant increases in population along the coastline in the past three decades. With this increase in population have come changes to the land surface, as forest and farmland has been converted to residential and commercial purposes, causing changes in the surface roughness, temperature, and land-atmosphere fluxes. There is also a semi-permanent upwelling center in the spring and summer outside the Delaware Bay mouth that significantly changes the structure of the sea surface temperature both inside and outside the Bay. Through a series of high resolution modeling and observational studies, we have determined that in cases of strong synoptic forcing, the impact of the land-surface on the boundary layer properties can be advected offshore, creating a false coastline and modifying the location and timing of the sea breeze circulation. In cases of weak synoptic forcing, the influence of the upwelling and the tidal circulation of the Delaware Bay waters can greatly change the location, strength, and penetration of the sea breeze. Understanding the importance of local variability in the surface-atmosphere interactions on the sea breeze can lead to improved prediction of sea breeze onset, penetration, and duration which is important for monitoring air quality and developing offshore wind power production.

Eastern rim of the Chesapeake Bay impact crater: Morphology, stratigraphy, and structure

USGS Publications Warehouse

Poag, C.W.

2005-01-01

This study reexamines seven reprocessed (increased vertical exaggeration) seismic reflection profiles that cross the eastern rim of the Chesapeake Bay impact crater. The eastern rim is expressed as an arcuate ridge that borders the crater in a fashion typical of the "raised" rim documented in many well preserved complex impact craters. The inner boundary of the eastern rim (rim wall) is formed by a series of raterfacing, steep scarps, 15-60 m high. In combination, these rim-wall scarps represent the footwalls of a system of crater-encircling normal faults, which are downthrown toward the crater. Outboard of the rim wall are several additional normal-fault blocks, whose bounding faults trend approximately parallel to the rim wall. The tops of the outboard fault blocks form two distinct, parallel, flat or gently sloping, terraces. The innermost terrace (Terrace 1) can be identified on each profile, but Terrace 2 is only sporadically present. The terraced fault blocks are composed mainly of nonmarine, poorly to moderately consolidated, siliciclastic sediments, belonging to the Lower Cretaceous Potomac Formation. Though the ridge-forming geometry of the eastern rim gives the appearance of a raised compressional feature, no compelling evidence of compressive forces is evident in the profiles studied. The structural mode, instead, is that of extension, with the clear dominance of normal faulting as the extensional mechanism. 

Notification: Review of the EPA’s Assessment of Potential Mining Impacts in Bristol Bay, Alaska

EPA Pesticide Factsheets

Project #OPE-FY14-0039, May 2, 2014. The EPA OIG plans to begin preliminary research to determine whether the EPA adhered to laws in developing its assessment of potential mining impacts on ecosystems in Bristol Bay, Alaska.

Environmental management of a highly impacted, urbanized tropical estuary: rehabilitation and restoration

NASA Astrophysics Data System (ADS)

Thorhaug, A.

1980-03-01

The principles of the dynamics and interrelationships within the dominant subtropical and tropical Caribbean seagrass community have been studied previously before, during, and after impact. From these and scores of observations of damage and recovery patterns in Thalassia ecosystems, a sense of management recovery strategy has emerged. Artificial restoring of Thalassia testudinum seeds into areas cut off from stock (fruit, seeds) appeared feasible on a large scale after the Turkey Point (Biscayne Bay, Miami, Florida) restoration and test sampling throughout North Biscayne Bay. Two large-scale seeding attempts were made; after 11 months they compared favorably with Turkey Point specimens with regard to growth parameters, despite the turbidity and other persistent pollution. Thus, the possible areas in which Thalassia seed restoration can be used has increased to include estuaries of multiple impact still in various stages of recovery after physical and sewage pollution. This technique should be especially useful to “developing” nations where important nearshore fisheries nurseries based on Thalassia ecosystems have been heavily damaged and now lie barren. Man's impact on the estuary where seed restoration was attempted includes the following activities: 50% of the bay bottom directly dredged or filled (leaving much unconsolidated sediment); 50 million gallons of domestic waste dumped directly into a low flushing part of the bay for 20 years; seven major causeways transecting the bay, restricting circulation and flushing; two artificial inlets made into navigational channels; freshwater sheet flow drastically changed due to channelization by flood-control canals; urban runoff from a million people entering the bay. Most of the impacts have now abated; however, their long-term effects remain.

A shock-induced polymorph of anatase and rutile from the Chesapeake Bay impact structure, Virginia, U.S.A

USGS Publications Warehouse

Jackson, J.C.; Horton, J. Wright; Chou, I.-Ming; Belkin, H.E.

2006-01-01

A shock-induced polymorph (TiO2II) of anatase and rutile has been identified in breccias from the late Eocene Chesapeake Bay impact structure. The breccia samples are from a recent, partially cored test hole in the central uplift at Cape Charles, Virginia. The drill cores from 744 to 823 m depth consist of suevitic crystalline-clast breccia and brecciated cataclastic gneiss in which the TiO2 phases anatase and rutile are common accessory minerals. Electron-microprobe imaging and laser Raman spectroscopy of TiO2 crystals, and powder X-ray diffraction (XRD) of mineral concentrates, confirm that a high-pressure, ??-PbO2 structured polymorph of TiO2 (TiO2II) coexists with anatase and rutile in matrix-hosted crystals and in inclusions within chlorite. Raman spectra of this polymorph include strong bands at wavenumbers (cm-1) 175, 281, 315, 342, 356, 425, 531, 571, and 604; they appear with anatase bands at 397, 515, and 634 cm-1, and rutile bands at 441 and 608 cm-1. XRD patterns reveal 12 lines from the polymorph that do not significantly interfere with those of anatase or rutile, and are consistent with the TiO2II that was first reported to occur naturally as a shock-induced phase in rutile from the Ries crater in Germany. The recognition here of a second natural shock-induced occurrence of TiO2II suggests that its presence in rocks that have not been subjected to ultrahigh-pressure regional metamorphism can be a diagnostic indicator for confirmation of suspected impact structures.

75 FR 29574 - Final Legislative Environmental Impact Statement for the Harvest of Glaucous-Winged Gull Eggs by...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-26

... for the Harvest of Glaucous-Winged Gull Eggs by the Huna Tlingit in Glacier Bay National Park AGENCY... Impact Statement for the Harvest of Glaucous-Winged Gull Eggs by the Huna Tlingit in Glacier Bay National... Environmental Impact Statement (LEIS) for the harvest of glaucous-winged gull eggs by the Huna Tlingit in...

Chesapeake Bay Watershed - Protecting the Chesapeake Bay and its rivers through science, restoration, and partnership

USGS Publications Warehouse

,

2012-01-01

The Chesapeake Bay, the Nation's largest estuary, has been degraded due to the impact of human-population increase, which has doubled since 1950, resulting in degraded water quality, loss of habitat, and declines in populations of biological communities. Since the mid-1980s, the Chesapeake Bay Program (CBP), a multi-agency partnership which includes the Department of Interior (DOI), has worked to restore the Bay ecosystem. The U.S. Geological Survey (USGS) has the critical role of providing unbiased scientific information that is utilized to document and understand ecosystem change to help assess the effectiveness of restoration strategies in the Bay and its watershed. The USGS revised its Chesapeake Bay science plan for 2006-2011 to address the collective needs of the CBP, DOI, and USGS with a mission to provide integrated science for improved understanding and management of the Bay ecosystem. The USGS science themes for this mission are: Causes and consequences of land-use change; Impact of climate change and associated hazards; Factors affecting water quality and quantity; Ability of habitat to support fish and bird populations; and Synthesis and forecasting to improve ecosystem assessment, conservation, and restoration.

BUZZARDS BAY EMBAYMENTS, BAYWATCHERS II: NUTRIENT RELATED WATER QUALITY 1992-1998

EPA Science Inventory

Since 1992, the Buzzards Bay Citizens' Water Quality Monitoring Program, known as "Baywatchers", has been monitoring and evaluating bay water quality and particularly the impacts of nitrogen loading. More than 300 dedicated citizen volunteers have contributed to the effort, sampl...

Collaborating at a Regional Scale for Climate Literacy and Action

NASA Astrophysics Data System (ADS)

Carlton, C.; Shcherba, O.

2016-12-01

Since 2014, the Bay Area Climate Literacy Impact Collaborative (Bay-CLIC) has been the leading regional consortium dedicated to improving climate education and action. Collectively, Bay-CLIC members reach over 3 million individuals through their educational programming, serve counties all throughout the Bay Area, offer multiple methods of climate communication like place-based school programs and visitor centers, and serve audiences representing all age groups. With over 30 organizations ranging from park agencies to science museums and nonprofits promoting energy efficiency, Bay-CLIC is preparing to push out climate change messaging through a suite of projects. Currently, Bay-CLIC's work is centered on building connections between educators and local scientists and region-specific climate data, implementing joint campaigns to promote the social norming of sustainable behavior change, and developing a toolkit and trainings targeted to the needs of Bay Area environmental educators. Meeting the needs of this diverse group offers many opportunities for increasing impact, growing new, strategic partnerships, as well as overcoming a few challenges along the way. Come learn more about what we've accomplished so far and what new, exciting projects are coming down the pike.

Environmental and Sanitary Conditions of Guanabara Bay, Rio de Janeiro

PubMed Central

Fistarol, Giovana O.; Coutinho, Felipe H.; Moreira, Ana Paula B.; Venas, Tainá; Cánovas, Alba; de Paula, Sérgio E. M.; Coutinho, Ricardo; de Moura, Rodrigo L.; Valentin, Jean Louis; Tenenbaum, Denise R.; Paranhos, Rodolfo; do Valle, Rogério de A. B.; Vicente, Ana Carolina P.; Amado Filho, Gilberto M.; Pereira, Renato Crespo; Kruger, Ricardo; Rezende, Carlos E.; Thompson, Cristiane C.; Salomon, Paulo S.; Thompson, Fabiano L.

2015-01-01

Guanabara Bay is the second largest bay in the coast of Brazil, with an area of 384 km2. In its surroundings live circa 16 million inhabitants, out of which 6 million live in Rio de Janeiro city, one of the largest cities of the country, and the host of the 2016 Olympic Games. Anthropogenic interference in Guanabara Bay area started early in the XVI century, but environmental impacts escalated from 1930, when this region underwent an industrialization process. Herein we present an overview of the current environmental and sanitary conditions of Guanabara Bay, a consequence of all these decades of impacts. We will focus on microbial communities, how they may affect higher trophic levels of the aquatic community and also human health. The anthropogenic impacts in the bay are flagged by heavy eutrophication and by the emergence of pathogenic microorganisms that are either carried by domestic and/or hospital waste (e.g., virus, KPC-producing bacteria, and fecal coliforms), or that proliferate in such conditions (e.g., vibrios). Antibiotic resistance genes are commonly found in metagenomes of Guanabara Bay planktonic microorganisms. Furthermore, eutrophication results in recurrent algal blooms, with signs of a shift toward flagellated, mixotrophic groups, including several potentially harmful species. A recent large-scale fish kill episode, and a long trend decrease in fish stocks also reflects the bay’s degraded water quality. Although pollution of Guanabara Bay is not a recent problem, the hosting of the 2016 Olympic Games propelled the government to launch a series of plans to restore the bay’s water quality. If all plans are fully implemented, the restoration of Guanabara Bay and its shores may be one of the best legacies of the Olympic Games in Rio de Janeiro. PMID:26635734

Pore-water chemistry from the ICDP-USGS core hole in the Chesapeake Bay impact structure-Implications for paleohydrology, microbial habitat, and water resources

USGS Publications Warehouse

Sanford, W.E.; Voytek, M.A.; Powars, D.S.; Jones, B.F.; Cozzarelli, I.M.; Cockell, C.S.; Eganhouse, R.P.

2009-01-01

We investigated the groundwater system of the Chesapeake Bay impact structure by analyzing the pore-water chemistry in cores taken from a 1766-m-deep drill hole 10 km north of Cape Charles, Virginia. Pore water was extracted using high-speed centrifuges from over 100 cores sampled from a 1300 m section of the drill hole. The pore-water samples were analyzed for major cations and anions, stable isotopes of water and sulfate, dissolved and total carbon, and bioavailable iron. The results reveal a broad transition between freshwater and saline water from 100 to 500 m depth in the postimpact sediment section, and an underlying synimpact section that is almost entirely filled with brine. The presence of brine in the lowermost postimpact section and the trend in dissolved chloride with depth suggest a transport process dominated by molecular diffusion and slow, compaction-driven, upward flow. Major ion results indicate residual effects of diagenesis from heating, and a pre-impact origin for the brine. High levels of dissolved organic carbon (6-95 mg/L) and the distribution of electron acceptors indicate an environment that may be favorable for microbial activity throughout the drilled section. The concentration and extent of the brine is much greater than had previously been observed, suggesting that its occurrence may be common in the inner crater. However, groundwater-flow conditions in the structure may reduce the saltwater-intrusion hazard associated with the brine. ?? 2009 The Geological Society of America.

Subsurface structure of the East Bay Plain ground-water basin: San Francisco Bay to the Hayward fault, Alameda County, California

USGS Publications Warehouse

Catchings, R.D.; Borchers, J.W.; Goldman, M.R.; Gandhok, G.; Ponce, D.A.; Steedman, C.E.

2006-01-01

The area of California between the San Francisco Bay, San Pablo Bay, Santa Clara Valley, and the Diablo Ranges (East Bay Hills), commonly referred to as the 'East Bay', contains the East Bay Plain and Niles Cone ground-water basins. The area has a population of 1.46 million (2003 US Census), largely distributed among several cities, including Alameda, Berkeley, Fremont, Hayward, Newark, Oakland, San Leandro, San Lorenzo, and Union City. Major known tectonic structures in the East Bay area include the Hayward Fault and the Diablo Range to the east and a relatively deep sedimentary basin known as the San Leandro Basin beneath the eastern part of the bay. Known active faults, such as the Hayward, Calaveras, and San Andreas pose significant earthquake hazards to the region, and these and related faults also affect ground-water flow in the San Francisco Bay area. Because most of the valley comprising the San Francisco Bay area is covered by Holocene alluvium or water at the surface, our knowledge of the existence and locations of such faults, their potential hazards, and their effects on ground-water flow within the alluvial basins is incomplete. To better understand the subsurface stratigraphy and structures and their effects on ground-water and earthquake hazards, the U.S. Geological Survey (USGS), in cooperation with the East Bay Municipal Utility District (EBMUD), acquired a series of high-resolution seismic reflection and refraction profiles across the East Bay Plain near San Leandro in June 2002. In this report, we present results of the seismic imaging investigations, with emphasis on ground water.

Marsh canopy structure changes and the Deepwater Horizon oil spill

USGS Publications Warehouse

Ramsey, Elijah W.; Rangoonwala, Amina; Jones, Cathleen E.

2016-01-01

Marsh canopy structure was mapped yearly from 2009 to 2012 in the Barataria Bay, Louisiana coastal region that was impacted by the 2010 Deepwater Horizon (DWH) oil spill. Based on the previously demonstrated capability of NASA's UAVSAR polarimetric synthetic aperture radar (PolSAR) image data to map Spartina alterniflora marsh canopy structure, structure maps combining the leaf area index (LAI) and leaf angle distribution (LAD, orientation) were constructed for yearly intervals that were directly relatable to the 2010 LAI-LAD classification. The yearly LAI-LAD and LAI difference maps were used to investigate causes for the previously revealed dramatic change in marsh structure from prespill (2009) to postspill (2010, spill cessation), and the occurrence of structure features that exhibited abnormal spatial and temporal patterns. Water level and salinity records showed that freshwater releases used to keep the oil offshore did not cause the rapid growth from 2009 to 2010 in marsh surrounding the inner Bay. Photointerpretation of optical image data determined that interior marsh patches exhibiting rapid change were caused by burns and burn recovery, and that the pattern of 2010 to 2011 LAI decreases in backshore marsh and extending along some tidal channels into the interior marsh were not associated with burns. Instead, the majority of 2010 to 2011 shoreline features aligned with vectors displaying the severity of 2010 shoreline oiling from the DWH spill. Although the association is not conclusive of a causal oil impact, the coexistent pattern is a significant discovery. PolSAR marsh structure mapping provided a unique perspective of marsh biophysical status that enhanced detection of change and monitoring of trends important to management effectiveness.

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.

EPA H2O Software Tool

EPA Science Inventory

EPA H2O allows user to: Understand the significance of EGS in Tampa Bay watershed; visually analyze spatial distribution of the EGS in Tampa Bay watershed; obtain map and summary statistics of EGS values in Tampa Bay watershed; analyze and compare potential impacts of development...

Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi

USGS Publications Warehouse

DeWitt, Nancy T.; Stalk, Chelsea A.; Smith, Christopher G.; Locker, Stanley D.; Fredericks, Jake J.; McCloskey, Terrence A.; Wheaton, Cathryn J.

2017-12-01

As part of the Sea-level and Storm Impacts on Estuarine Environments and Shorelines (SSIEES) project, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted a single-beam bathymetry survey within the estuarine, open-bay, and tidal creek environments of Grand Bay, Alabama-Mississippi, from May to June 2015. The goal of the SSIEES project is to assess the physical controls of sediment and material exchange between wetlands and estuarine environments along the northern Gulf of Mexico, specifically Grand Bay, Alabama-Mississippi; Vermilion Bay, Louisiana; and, along the east coast, within Chincoteague Bay, Virginia-Maryland. The data described in this report provide baseline bathymetric information for future research investigating wetland-marsh evolution, sediment transport, erosion, recent and long-term geomorphic change, and can also support the modeling of changes in response to restoration and storm impacts. The survey area encompasses more than 40 square kilometers of Grand Bay’s waters.

Environmental consequences of the flooding of the Bay Park Sewage Treatment Plant during Superstorm Sandy.

PubMed

Swanson, R Lawrence; Wilson, Robert; Brownawell, Bruce; Willig, Kaitlin

2017-08-15

Failure of the Bay Park Sewage Treatment Plant (STP) during Superstorm Sandy led to adverse effects in the waters of Hempstead Bay, Long Island, NY. These appear to be related to large discharges of partially treated sewage through its primary and auxiliary outfalls. Modeled dilution discharges indicate that sewage infiltrated the bay, remaining up to 10days. Water column impacts included salinity and dissolved oxygen declines, and biological oxygen demand and nitrogen concentration increases. While the STP does not appear to have released fecal coliform, there were elevated levels of enterococci within the bay for a considerable period following the storm, probably from multiple sources. The STP's reduced functioning and associated environmental impacts, even with resilience upgrades, are not conducive to removing the bay from the list of Impaired Water Bodies. The results reinforce the need to transfer the discharge from the existing outfall to the ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chesapeake Bay: Introduction to an Ecosystem.

ERIC Educational Resources Information Center

Environmental Protection Agency, Washington, DC.

The Chesapeake Bay is the largest estuary in the contiguous United States. The Bay and its tidal tributaries make up the Chesapeake Bay ecosystem. This document, which focuses of various aspects of this ecosystem, is divided into four major parts. The first part traces the geologic history of the Bay, describes the overall physical structure of…

Macrofaunal community structure in Bahía Concepción (Chile) before and after the 8.8 Mw Maule mega-earthquake and tsunami.

PubMed

Cárcamo, Paula J; Hernández-Miranda, Eduardo; Veas, Rodrigo; Quiñones, Renato A

2017-09-01

Faunal assemblages of subtidal sedimentary environments are key components of coastal ecosystems. Benthic communities inhabiting the coastal zone near urban centers in Concepción Bay (Chile) have been described as highly disturbed (i.e. impoverished in diversity and species richness). This is due to the frequent presence of hypoxic conditions at the bottom due to the intrusion of low oxygen Equatorial Subsurface Water, high natural productivity and the high load of organic matter generated by several anthropogenic activities. A mega-earthquake (8.8 Mw) and subsequent tsunami occurred on the coast of south-central Chile on February 27, 2010 (27F), heavily impacting Concepción Bay, which is located 30 km south of the epicenter. The objectives of the present study are: (i) to evaluate the effect produced by the mega-earthquake and tsunami on the benthic community, and (ii) to assess dissimilarity in macrofauna composition and abundance in Concepción Bay at an inter-decadal time scale based on a comparison between our sampling conducted between 2010 and 2013 and information published since 1969. Our results show that the benthic macrofauna of Concepción Bay was disturbed by the 27F (i.e. high community dissimilarity in 2010). Changes in community structure were observed at an inter-annual scale (i.e. diminished community dissimilarity in 2013), suggesting a recovery post-27F. At an inter-decadal scale, community structure post-27F was dissimilar to the structure described for the 1980's and 1990's but more similar to that reported for 1969. The reducing conditions of the sediments due to the high input of organic matter that took place in the 1980's and 1990's may explain this dissimilarity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of potential ecological impacts associated with a POTW located on Hempstead Bay, New York

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

Harman, C.R.; Brockerhoff, F.G.; D`Alleinne, C.P.

1995-12-31

The Hempstead Bay estuary is a broad, shallow complex that is separated from the Atlantic Ocean by a series of barrier islands (Jones and Long Beaches). Hempstead Bay is divided into West Bay, Middle Bay, and East Bay components by a series of marsh islands. The West Bay portion is influenced by tidal exchange through the East Rockaway Inlet. The West Bay in particular, and the Hempstead Bay in general, receive an extensive load of potential contaminants from numerous sources including point and non-point residential and industrial source discharges, storm water runoff, possible migration of leachate from landfills adjacent tomore » the Bay, and the effluent from several wastewater treatment facilities. The objective of this ongoing project is to evaluate whether the operations of a particular wastewater treatment facility located adjacent to the West Bay portion of Hempstead Bay is impacting aquatic resources in the vicinity of the plant. Additionally, there is a concern that potential COIs may be migrating into the West Bay from treatment plant sludge that was used in the construction of a local golf course. The ecological evaluation will consist of a semi-quantitative ecological risk assessment, supported by two rounds of sediment and surface water samples collected from the aquatic environment surrounding the plant and associated areas of interest. Surface water and sediment samples will be analyzed for a variety of parameters including TCL volatile organic compounds, TCL semivolatile organic compounds, TCL pesticides/PCBs and Target Analyte List (TAL) inorganic constituents. The results of that sampling and the preliminary evaluation of the resulting data are presented in this paper.« less

Megablocks and melt pockets in the Chesapeake Bay impact structure constrained by magnetic field measurements and properties of the Eyreville and Cape Charles cores

USGS Publications Warehouse

Shah, A.K.; Daniels, D.L.; Kontny, A.; Brozena, J.

2009-01-01

We use magnetic susceptibility and remanent magnetization measurements of the Eyreville and Cape Charles cores in combination with new and previously collected magnetic field data in order to constrain structural features within the inner basin of the Chesapeake Bay impact structure. The Eyreville core shows the first evidence of several-hundred-meter-thick basement-derived megablocks that have been transported possibly kilometers from their pre-impact location. The magnetic anomaly map of the structure exhibits numerous short-wavelength (<2 km) variations that indicate the presence of magnetic sources within the crater fill. With core magnetic properties and seismic reflection and refraction results as constraints, forward models of the magnetic field show that these sources may represent basementderived megablocks that are a few hundred meters thick or melt bodies that are a few dozen meters thick. Larger-scale magnetic field properties suggest that these bodies overlie deeper, pre-impact basement contacts between materials with different magnetic properties such as gneiss and schist or gneiss and granite. The distribution of the short-wavelength magnetic anomalies in combination with observations of small-scale (1-2 mGal) gravity field variations suggest that basement-derived megablocks are preferentially distributed on the eastern side of the inner crater, not far from the Eyreville core, at depths of around 1-2 km. A scenario where additional basement-derived blocks between 2 and 3 km depth are distributed throughout the inner basin-and are composed of more magnetic materials, such as granite and schist, toward the east over a large-scale magnetic anomaly high and less magnetic materials, such as gneiss, toward the west where the magnetic anomaly is lower-provides a good model fi t to the observed magnetic anomalies in a manner that is consistent with both gravity and seismic-refraction data. ?? 2009 The Geological Society of America.

Bristol Bay Assessment – Supplemental Peer Review Reports (May 2012)

EPA Science Inventory

These reports represent the results of independent peer reviews of several technical reports submitted to the public docket for the May 2012 draft of the Bristol Bay Assessment, An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska.

...

Design and Use of a Guided Weight Impactor to Impart Barely Visible Impact Damage

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Przekop, Adam

2016-01-01

Aircraft structure is required to demonstrate satisfaction of the FAR requirements for Category 1, such as barely visible impact damage (BVID). Typical aircraft structure is impacted using a dropped weight impactor, which can impart BVID to the top surface of the structure. A recent test of a multi-bay box (MBB) composite test article, that represents an 80% scale center section of a hybrid wing body aircraft, required impact to be in a direction other than vertical from above, but still in an direction that is normal to the surface. This requirement eliminated the use of the conventional dropped weight impactor. Therefore, a design study was undertaken to determine the most effective way to efficiently and reliably impact the MBB. The chosen design was a guided weight impactor that is gravity driven. This paper describes the design of the guided weight impactor, and presents the results of its use for imparting BVID to the MBB. The guided weight impactor was seen to be a very reliable method to impart BVID, while at the same time having the capability to be highly configurable for use on other aircraft structure that is impacted at a variety of impact energies and from a variety of directions.

Mean sea-level rise impacts on Santos Bay, Southeastern Brazil--physical modelling study.

PubMed

Alfredini, Paolo; Arasaki, Emilia; do Amaral, Rogério Fernando

2008-09-01

The greenhouse effect and resulting increase in the Earth's temperature may accelerate the mean sea-level rise. The natural response of bays and estuaries to this rise, such as this case study of Santos Bay (Brazil), will include change in shoreline position, land flooding and wetlands impacts. The main impacts of this scenario were studied in a physical model built in the Coastal and Harbour Division of Hydraulic Laboratory, University of São Paulo, and the main conclusions are presented in this paper. The model reproduces near 1,000 km(2) of the study area, including Santos, São Vicente, Praia Grande, Cubatão, Guarujá and Bertioga cities.

Some Challenges of an “Upside Down” Nitrogen Budget – Science and Management in Greenwich Bay, RI (USA)

EPA Science Inventory

When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Prev...

Modeling Historical and Projected Future Atmospheric Nitrogen Loading to the Chesapeake Bay Watershed

EPA Science Inventory

Land use and climate change are expected to alter key processes in the Chesapeake Bay watershed and can potentially exacerbate the impact of excess nitrogen. Atmospheric sources are one of the largest loadings of nitrogen to the Chesapeake Bay watershed. In this study, we explore...

Assessing the impacts of salinity and nutrient stress to Ruppia maritima and Zostera marina.

EPA Science Inventory

Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have disappeared due to infilling, pollution and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, Ruppia maritima has colonized an area on the northern...

An Adaptive Model of Student Performance Using Inverse Bayes

ERIC Educational Resources Information Center

Lang, Charles

2014-01-01

This article proposes a coherent framework for the use of Inverse Bayesian estimation to summarize and make predictions about student behaviour in adaptive educational settings. The Inverse Bayes Filter utilizes Bayes theorem to estimate the relative impact of contextual factors and internal student factors on student performance using time series…

IMPACTS OF SALINITY AND NUTRIENT STRESS TO RUPPIA MARITIMA AND ZOSTERA MARINA: A MESOCOSM EXPERIMENT

EPA Science Inventory

Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have disappeared due to infilling, pollution and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, Ruppia maritima has colonized an area on the norther...

ASSESSING THE IMPACTS OF SALINITY AND NUTRIENT STRESS TO RUPPIA MARITIMA AND ZOSTERA MARINA

EPA Science Inventory

Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have disappeared due to infilling, pollution and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, Ruppia maritima has colonized an area on the norther...

Imparting Barely Visible Impact Damage to a Stitched Composite Large-Scale Pressure Box

NASA Technical Reports Server (NTRS)

Lovejoy, Andrew E.; Przekop, Adam

2016-01-01

The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body (HWB) aircraft configuration, which has been a focus of the NASA Environmentally Responsible Aviation Project. The NASA-Boeing structural development for the HWB aircraft culminated in testing of the multi-bay box, which is an 80%-scale representation of the pressurized center-body section. This structure was tested in the NASA Langley Research Center Combined Loads Test System facility. As part of this testing, barely visible impact damage was imparted to the interior and exterior of the test article to demonstrate compliance with a condition representative of the requirements for Category 1 damaged composite structure as defined by the Federal Aviation Regulations. Interior impacts were imparted using an existing spring-loaded impactor, while the exterior impacts were imparted using a newly designed, gravity-driven impactor. This paper describes the impacts to the test article, and the design of the gravitydriven guided-weight impactor. The guided-weight impactor proved to be a very reliable method to impart barely visible impact damage in locations which are not easily accessible for a traditional drop-weight impactor, while at the same time having the capability to be highly configurable for use on other aircraft structures.

396. Delineator Unknown Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

396. Delineator Unknown Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; EAST BAY CROSSING; CANTILEVER STRUCTURE; DETAILS I; DRG. NO. 68 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

397. Delineator Unknown Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

397. Delineator Unknown Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; EAST BAY CROSSING; CANTILEVER STRUCTURE; DETAILS II; DRG. NO. 69 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Evolution of crystalline target rocks and impactites in the chesapeake bay impact structure, ICDP-USGS eyreville B core

USGS Publications Warehouse

Horton, J. Wright; Kunk, Michael J.; Belkin, Harvey E.; Aleinikoff, John N.; Jackson, John C.; Chou, I.-Ming

2009-01-01

The 1766-m-deep Eyreville B core from the late Eocene Chesapeake Bay impact structure includes, in ascending order, a lower basement-derived section of schist and pegmatitic granite with impact breccia dikes, polymict impact breccias, and cataclas tic gneiss blocks overlain by suevites and clast-rich impact melt rocks, sand with an amphibolite block and lithic boulders, and a 275-m-thick granite slab overlain by crater-fill sediments and postimpact strata. Graphite-rich cataclasite marks a detachment fault atop the lower basement-derived section. Overlying impactites consist mainly of basement-derived clasts and impact melt particles, and coastal-plain sediment clasts are underrepresented. Shocked quartz is common, and coesite and reidite are confirmed by Raman spectra. Silicate glasses have textures indicating immiscible melts at quench, and they are partly altered to smectite. Chrome spinel, baddeleyite, and corundum in silicate glass indicate high-temperature crystallization under silica undersaturation. Clast-rich impact melt rocks contain α-cristobalite and monoclinic tridymite. The impactites record an upward transition from slumped ground surge to melt-rich fallback from the ejecta plume. Basement-derived rocks include amphibolite-facies schists, greenschist(?)-facies quartz-feldspar gneiss blocks and subgreenschist-facies shale and siltstone clasts in polymict impact breccias, the amphibolite block, and the granite slab. The granite slab, underlying sand, and amphibolite block represent rock avalanches from inward collapse of unshocked bedrock around the transient crater rim. Gneissic and massive granites in the slab yield U-Pb sensitive high-resolution ion microprobe (SHRIMP) zircon dates of 615 ± 7 Ma and 254 ± 3 Ma, respectively. Postimpact heating was <~350 °C in the lower basement-derived section based on undisturbed 40Ar/39Ar plateau ages of muscovite and <~150 °C in sand above the suevite based on 40Ar/39Ar age spectra of detrital microcline.

IMPACT OF STORM-WATER OUTFALLS ON SEDIMENT QUALITY IN CORPUS CHRISTI BAY, TEXAS, USA

EPA Science Inventory

To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industr...

An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska (First External Review Draft)

EPA Science Inventory

[UPDATE] In March 2014, EPA released a response to public comments on the draft document, "An Assessment of the Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska" (see downloads). In Jan 2014, EPA released a response to peer review comments on ...

An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska (Second External Review Draft)

EPA Science Inventory

[UPDATE] In March 2014, EPA released a response to public comments on the second draft document, "An Assessment of the Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska" (see downloads). In Jan 2014, EPA released a response to peer review comme...

Comparing an ecosystem approach to single-species stock assessment: The case of Gazi Bay, Kenya

NASA Astrophysics Data System (ADS)

Tuda, Paul M.; Wolff, Matthias

2018-08-01

Gazi Bay located on the Kenyan South Coast is a semi-enclosed shallow tropical coastal ecosystem supporting an economically important multi-species and multi-gear artisanal fishery. In this study, we integrated the available scientific information of the system to develop a preliminary trophic mass-balance model to characterize the ecosystem structure and functioning, evaluate the ecological impacts of fishing on the ecosystem, and compare the results of the ecosystem assessment to those of previous single-species stock assessments. The model includes 23 functional groups aggregated into linear food chains, which resulted in nine discrete trophic levels sensu Lindeman (1942). Results from the mixed trophic impacts showed a bottom-up control in the system where herbivory dominated the energy flow to higher trophic levels but with a significant export of detritus out of the system. With a mean transfer efficiency of 12.6%, Finn cycling index 7.3%, path length 2.7, system omnivory index 0.19, and system ascendency and overhead 27 and 73%, respectively, it would appear that Gazi Bay is immature and perturbed likely due to fishery-induced exploitation. Overall, the fishery is operating at a level of primary consumers with a mean trophic level of the catch of 2.38. Fishing mortality is by far the leading cause of total mortality with the computed exploitation rates suggesting heavy exploitation of the key commercial species (F/Z > 0.5). A comparison of the results of the percentage of primary production required to sustain fisheries and the average trophic level of catch (%PPR-TLc) with those from similar tropical coastal systems shows that Gazi Bay is comparable to some of the most intensively exploited coastal ecosystems. This implies the impacts of the fishery are evident both at the species and ecosystem level, and there may be a need for precautionary measures for fisheries management.

Sedimentary and Vegetative Impacts of Hurricane Irma to Coastal Wetland Ecosystems across Southwest Florida

NASA Astrophysics Data System (ADS)

Moyer, R. P.; Khan, N.; Radabaugh, K.; Engelhart, S. E.; Smoak, J. M.; Horton, B.; Rosenheim, B. E.; Kemp, A.; Chappel, A. R.; Schafer, C.; Jacobs, J. A.; Dontis, E. E.; Lynch, J.; Joyse, K.; Walker, J. S.; Halavik, B. T.; Bownik, M.

2017-12-01

Since 2014, our collaborative group has been working in coastal marshes and mangroves across Southwest Florida, including Tampa Bay, Charlotte Harbor, Ten Thousand Islands, Biscayne Bay, and the lower Florida Keys. All existing field sites were located within 50 km of Hurricane Irma's eye path, with a few sites in the Lower Florida Keys and Naples/Ten Thousand Islands region suffering direct eyewall hits. As a result, we have been conducting storm-impact and damage assessments at these locations with the primary goal of understanding how major hurricanes contribute to and/or modify the sedimentary record of mangroves and salt marshes. We have also assessed changes to the vegetative structure of the mangrove forests at each site. Preliminary findings indicate a reduction in mangrove canopy cover from 70-90% pre-storm, to 30-50% post-Irma, and a reduction in tree height of approximately 1.2 m. Sedimentary deposits consisting of fine carbonate mud up to 12 cm thick were imported into the mangroves of the lower Florida Keys, Biscayne Bay, and the Ten Thousand Islands. Import of siliciclastic mud up to 5 cm thick was observed in Charlotte Harbor. In addition to fine mud, all sites had imported tidal wrack consisting of a mixed seagrass and mangrove leaf litter, with some deposits as thick as 6 cm. In areas with newly opened canopy, a microbial layer was coating the surface of the imported wrack layer. Overwash and shoreline erosion were also documented at two sites in the lower Keys and Biscayne Bay, and will be monitored for change and recovery over the next few years. Because active research was being conducted, a wealth of pre-storm data exists, thus these locations are uniquely positioned to quantify hurricane impacts to the sedimentary record and standing biomass across a wide geographic area. Due to changes in intensity along the storm path, direct comparisons of damage metrics can be made to environmental setting, wind speed, storm surge, and distance to eyewall.

Tolerance to stress differs between Asian green mussels Perna viridis from the impacted Jakarta Bay and from natural habitats along the coast of West Java.

PubMed

Huhn, Mareike; Hattich, Giannina S I; Zamani, Neviaty P; von Juterzenka, Karen; Lenz, Mark

2016-09-30

It is an open question whether adverse habitat conditions, characteristic for many anthropogenically impacted coastal habitats, can determine resistance to abiotic stress in populations of residing invertebrates. We tested experimentally for differences in stress tolerance between individuals of the Asian green mussel Perna viridis stemming from the heavily impacted Jakarta Bay and from two natural sites, Lada Bay and Pelabuhan Ratu, West Java. Mussel performance under hyposalinity and hypoxia was assessed in laboratory assays by measuring fitness-related response variables, e.g. body condition index, relative shell weight, byssus production, respiration rates and survival. We found stress-specific and population-specific differences in mussel resistance to adverse conditions: Individuals from the impacted Jakarta Bay performed better under hypoxia than their conspecifics from the natural sites, whereas the latter were more resistant to hyposalinity. We explain these differences by differential acclimation to environmental conditions in the respective habitats and by diverging degrees of food supply. Copyright © 2016 Elsevier Ltd. All rights reserved.

Results of EVA/mobile transporter space station truss assembly tests

NASA Technical Reports Server (NTRS)

Watson, Judith J.; Heard, Walter L., Jr.; Bush, Harold G.; Lake, M. S.; Jensen, J. K.; Wallsom, R. E.; Phelps, J. E.

1988-01-01

Underwater neutral buoyance tests were conducted to evaluate the use of a Mobile Transporter concept in conjunction with EVA astronauts to construct the Space Station Freedom truss structure. A three-bay orthogonal tetrahedral truss configuration with a 15 foot square cross section was repeatedly assembled by a single pair of pressure suited test subjects working from the Mobile Transporter astronaut positioning devices (mobile foot restraints). The average unit assembly time (which included integrated installation of utility trays) was 27.6 s/strut, or 6 min/bay. The results of these tests indicate that EVA assembly of space station size structures can be significantly enhanced when using a Mobile Transporter equipped with astronaut positioning devices. Rapid assembly time can be expected and are dependent primarily on the rate of translation permissible for on-orbit operations. The concept used to demonstate integrated installation of utility trays requires minimal EVA handling and consequentially, as the results show, has little impact on overall assembly time.

Oceanic Impact: Mechanisms and Environmental Perturbations

NASA Technical Reports Server (NTRS)

Gersonde, Rainer (Editor); Deutsch, Alex (Editor); Ivanov, Boris A. (Editor); Kyte, Frank T. (Editor)

2002-01-01

The contents include the following: Oceanic impacts-a growing field of fundamental geoscience. Shock metamorphism on the ocean floor (numerical simulations). Numerical modeling of impact-induced modifications of the deep-sea floor. Computer modelling of the water resurge at a marine impact: the Lockne crater, Sweden. Experimental investigation of the role of water in impact vaporization chemistry. Calcareous plankton stratigraphy around the Pliocene Eltanin asteroid impact area (SE Pacific): documentation and application for geological and paleoceanographic reconstruction. Composition of impact melt debris from the Eltanin impact strewn field, Bellingshausen Sea. Iridium concentrations and abundances of meteoritic ejecta from the Eltanin impact in sediment cores from Polarstern expedition ANT XII/4. Unmelted meteoritic debris collected from Eltanin ejecta in Polarstern cores from expedition ANT XII/4. Impact tsunami-Eltanin. Ancient impact structures on modern continental shelves: The Chesapeake Bay, Montagnais, and Toms Canyon craters, Atlantic margin of North America. The Mjolnir marine impact crater porosity anomaly. Kardla (Hiiu-maa Island, Estonia) - the buried and well-preserved Ordovician marine impact structure. Long-term effect of the Kardla crater (Hiiu-maa, Estonia) on Late Ordovician carbonate sedimentation. The middle Devonian Kaluga impact crater (Russia): new interpretation of marine setting.

Spatial and overwinter changes in clam populations of San Pablo Bay, a semiarid estuary with highly variable freshwater inflow

USGS Publications Warehouse

Poulton, V.K.; Lovvorn, J.R.; Takekawa, John Y.

2004-01-01

In many estuaries worldwide, climate trends together with human diversion of fresh water have dramatically impacted the benthos. Such impacts have sometimes been complicated by exotic species, whose invasion and persistence can be mediated by wide variations in freshwater inflow. Monitoring such changes usually involves periodic samples at a few sites; but sampling that does not recognize variation at a range of spatial and seasonal scales may not reveal important benthic trends. San Pablo Bay, in northern San Francisco Bay, has extreme fluctuations in freshwater inflow. This bay also experienced a major benthic change with introduction of the Asian clam (Potamocorbula amurensis) in 1986. This species initially displaced the former community, but later appeared to vary in abundance depending on site and freshwater inflow. To investigate such patterns and provide guidelines for research and monitoring, we took 1746 core samples at six sites around San Pablo Bay from 19 October to 17 December 1999 and from 6 March to 19 April 2000. Most biomass consisted of the clams P. amurensis,Macoma balthica and Mya arenaria. Potamocorbula amurensis dominated the benthos at most sites in the fall and recruited a new cohort during winter, while there was weak recruitment in M. balthica and none in M. arenaria. At most but not all sites, densities of P. amurensis and M. arenaria declined dramatically over winter while M. balthica declined only slightly. The dominant clams had patch diameters >5 m at most but not all sites, and some showed inconsistent patch structure at scales of 100–1400 m. In this semiarid estuary with highly variable freshwater inflow, samples for research and monitoring should include multiple sites and seasons, and samples within sites should be ≥5 m apart to account for between-patch variation. Species abundance in winter 1999–2000 appeared to be affected by high freshwater inflows in 1997–1999, while spatial patterns were probably most affected by post-settlement dispersal and mortality.

381. J.H.E., Delineator Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

381. J.H.E., Delineator Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; WEST BAY CROSSING; SUSPENDED STRUCTURE; ERECTION; DRG. NO. 43 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Effects of Human Activities on Submarine Topography in Lingding Bay of the Pearl River Estuary During the Last Decade

NASA Astrophysics Data System (ADS)

WU, Z. Y.; Saito, Y.; Milliman, J. D.; Zhao, D.; Zhou, J.

2015-12-01

Estuaries have been the site of intensive human activities. During the past century, decreased fluvial water and sediment discharge, increasing land reclamation, changing climate, and rising sea level have had an ever-increasing impact on river deltas, particularly those deltas bordering Southeast Asia. Using six stages of navigational and bathymetric chart data from 1906 to 2013 and 2 years (2012,2013) single-beam bathymetric data, together with more than 50 years of fluvial discharge data, we document the impact of human activities on the Pearl River Delta and its estuary at Lingding Bay. Between 1906 and 2010, land reclamation decreased the bay's water area by ~300 km2 (>17%), mostly at the expense of the shrinking intertidal and shallow subtidal mudflats. Before 1980, the estuary was mainly governed by natural processes with slight net deposition, whereas after 1980 dredging in the estuary and large port engineering projects changed the estuarine topography by shallowing the shoals and deepening the troughs. From 1955 to 2010, the water volume of Lingding Bay decreased by 536 × 106 m3 for a net decrease of 9.7 × 106 m3 a year, which indicates that approximately 9.7 Mt/yr of sediment was deposited in Lingding Bay during that period. In 2012 and 2013, large-scale human activities within Lingding Bay included continued dredging plus a surge of sand excavation that changed local water depths by ±5 m/yr, far exceeding the range of natural topographic evolution in the estuary. The impacts of various human activities have significantly changed submarine topography in Lingding Bay of the complex Pearl River Estuary. With continuing economic expansion in the Pearl River Delta, Lingding Bay should continue to shrink in both area and water volume.

U.S. Geological Survey Science—Improving the value of the Chesapeake Bay watershed

USGS Publications Warehouse

Phillips, Scott W.; Hyer, Kenneth; Goldbaum, Elizabeth

2017-05-05

IntroductionCongress directed the Federal Government to work with States to restore the Nation’s largest estuary.Chesapeake Bay restoration provides important economic and ecological benefits:18 million people live and work in the Bay watershed and enjoy its benefits.3,600 types of fish, wildlife, and plants underpin the economic value of the Bay ecosystem.Poor water quality and habitat loss threaten restoration and negatively impact the economy.10 Goals to meet by 2025 through the Chesapeake Bay Program, a voluntary partnership.

76 FR 61475 - Environmental Impact Statement: Walton and Bay Counties, Florida

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-04

...) will be prepared for a proposed highway project in Walton and Bay Counties, Florida. FOR FURTHER... public and agency review and comment. Additional project information can be found at the following web... 98) in Walton County, FL. The FDOT refers to this project as West Bay Parkway, Segment 1. This...

Tidal Mixing Box Submodel for Tampa Bay: Calibration of Tidal Exchange Flows with the Parameter Estimation Tool (PEST)

EPA Science Inventory

In the mid-1990s the Tampa Bay Estuary Program proposed a nutrient reduction strategy focused on improving water clarity to promote seagrass expansion within Tampa Bay. A System Dynamics Model is being developed to evaluate spatially and temporally explicit impacts of nutrient r...

A sediment mesocosm experiment to determine if the remediation of a shoreline waste disposal site in Antarctica caused further environmental impacts.

PubMed

Stark, Jonathan S; Johnstone, Glenn J; Riddle, Martin J

2014-12-15

A shoreline waste disposal site at Casey Station, Antarctica was removed because it was causing impacts in the adjacent marine environment (Brown Bay). We conducted a field experiment to determine whether the excavation created further impacts. Trays of clean, defaunated sediment were deployed at two locations within Brown Bay and two control locations, two years prior to remediation. Trays were sampled one year before, 1month before, 1month after and two years after the excavation. An increase in metals was found at Brown Bay two years after the remediation. However there was little evidence of impacts on sediment assemblages. Communities at each location were different, but differences from before to after the remediation were comparable, indicating there were unlikely to have been further impacts. We demonstrate that abandoned waste disposal sites in hydrologically active places in Antarctica can be removed without creating greater adverse impacts to ecosystems downstream. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

389. J.H.E., Delineator Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

389. J.H.E., Delineator Date Unknown STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; WEST BAY CROSSING; SUSPENDED STRUCTURE; TYPICAL DETAILS; DRG. NO. 42 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Modeling the marine magnetic field of Bahía de Banderas, Mexico, confirms the half-graben structure of the bay

NASA Astrophysics Data System (ADS)

Alvarez, Román; López-Loera, Héctor; Arzate, Jorge

2010-06-01

An existing aeromagnetic survey flown on the central, western portion of Mexico did not include an important tectonic structure: Bahía de Banderas. The bay has an extension of approximately 1400 km 2 and is located within the Puerto Vallarta batholith, a granitic structure of Cretaceous origin. We report here the additional gathering of 5523 magnetic values on the bay, in order to complement the existing land aeromagnetic information; this allowed modeling the structure of the bay from the magnetic viewpoint. A late Miocene age has been proposed for the bay making it roughly contemporaneous with the first stages of separation of Baja California from mainland Mexico. Initially proposed as a graben, it was subsequently shown that its structure actually corresponds to a half-graben of the fault growth type, with reverse drag geometry; it appears to have been developed in response to an extensional process in the ˜ N-S direction. Valle de Banderas neighbors the bay constituting its eastern land continuation; it has also been proposed as a graben and it is also likely the result of an extensional process. However, it seems to be a structure more recently formed, probably around 5 Ma. The different time origin of the bay and of the valley is strengthened by the different alignment of the valley axis, where Ameca River flows and discharges into the bay, of around 30° from the trace of Banderas fault. The magnetic responses of the valley, aeromagnetic and terrestrial, support the existence of an extensional process. Upward and downward continuations of the magnetic fields show that Sierra de Vallejo and Sierra de Zapotán, to the NW of the valley, are deeply rooted structures and their magnetic responses are similar to those obtained in the Puerto Vallarta batholith; these characteristics support a common origin for them. Three magnetic profiles trending NNW are modeled across Bahía de Banderas. The models identify the structure as a half-graben with a listric main fault and reverse drag geometry, just as it was previously obtained elsewhere by an independent modeling process.

Seagrass Impact on Sediment Exchange Between Tidal Flats and Salt Marsh, and The Sediment Budget of Shallow Bays

NASA Astrophysics Data System (ADS)

Donatelli, Carmine; Ganju, Neil Kamal; Fagherazzi, Sergio; Leonardi, Nicoletta

2018-05-01

Seagrasses are marine flowering plants that strongly impact their physical and biological surroundings and are therefore frequently referred to as ecological engineers. The effect of seagrasses on coastal bay resilience and sediment transport dynamics is understudied. Here we use six historical maps of seagrass distribution in Barnegat Bay, USA, to investigate the role of these vegetated surfaces on the sediment storage capacity of shallow bays. Analyses are carried out by means of the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) numerical modeling framework. Results show that a decline in the extent of seagrass meadows reduces the sediment mass potentially stored within bay systems. The presence of seagrass reduces shear stress values across the entire bay, including unvegetated areas, and promotes sediment deposition on tidal flats. On the other hand, the presence of seagrasses decreases suspended sediment concentrations, which in turn reduces the delivery of sediment to marsh platforms. Results highlight the relevance of seagrasses for the long-term survival of coastal ecosystems, and the complex dynamics regulating the interaction between subtidal and intertidal landscapes.

A High-Authority/Low-Authority Control Strategy for Coupled Aircraft-Style Bays

NASA Technical Reports Server (NTRS)

Schiller, N. H.; Fuller, C. R.; Cabell, R. H.

2006-01-01

This paper presents a numerical investigation of an active structural acoustic control strategy for coupled aircraft-style bays. While structural coupling can destabilize or limit the performance of some model-based decentralized control systems, fullycoupled centralized control strategies are impractical for typical aircraft containing several hundred bays. An alternative is to use classical rate feedback with matched, collocated transducer pairs to achieve active damping. Unfortunately, due to the conservative nature of this strategy, stability is guaranteed at the expense of achievable noise reduction. Therefore, this paper describes the development of a combined control strategy using robust active damping in addition to a high-authority controller based on linear quadratic Gaussian (LQG) theory. The combined control system is evaluated on a tensioned, two-bay model using piezoceramic actuators and ideal point velocity sensors. Transducer placement on the two-bay structure is discussed, and the advantages of a combined control strategy are presented.

Suspension Bridge Structural Systems: Cable Suspension & Anchorage; Warren Stiffening ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Suspension Bridge Structural Systems: Cable Suspension & Anchorage; Warren Stiffening Truss; Upper & Lower Decks; Assembled System - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Fine-scale genetic population structure in a mobile marine mammal: inshore bottlenose dolphins in Moreton Bay, Australia.

PubMed

Ansmann, Ina C; Parra, Guido J; Lanyon, Janet M; Seddon, Jennifer M

2012-09-01

Highly mobile marine species in areas with no obvious geographic barriers are expected to show low levels of genetic differentiation. However, small-scale variation in habitat may lead to resource polymorphisms and drive local differentiation by adaptive divergence. Using nuclear microsatellite genotyping at 20 loci, and mitochondrial control region sequencing, we investigated fine-scale population structuring of inshore bottlenose dolphins (Tursiops aduncus) inhabiting a range of habitats in and around Moreton Bay, Australia. Bayesian structure analysis identified two genetic clusters within Moreton Bay, with evidence of admixture between them (F(ST) = 0.05, P = 0.001). There was only weak isolation by distance but one cluster of dolphins was more likely to be found in shallow southern areas and the other in the deeper waters of the central northern bay. In further analysis removing admixed individuals, southern dolphins appeared genetically restricted with lower levels of variation (AR = 3.252, π = 0.003) and high mean relatedness (r = 0.239) between individuals. In contrast, northern dolphins were more diverse (AR = 4.850, π = 0.009) and were mixing with a group of dolphins outside the bay (microsatellite-based STRUCTURE analysis), which appears to have historically been distinct from the bay dolphins (mtDNA Φ(ST) = 0.272, P < 0.001). This study demonstrates the ability of genetic techniques to expose fine-scale patterns of population structure and explore their origins and mechanisms. A complex variety of inter-related factors including local habitat variation, differential resource use, social behaviour and learning, and anthropogenic disturbances are likely to have played a role in driving fine-scale population structure among bottlenose dolphins in Moreton Bay. © 2012 Blackwell Publishing Ltd.

Human and riverine impacts on the dynamics of biogeochemical parameters in Kwangyang Bay, South Korea revealed by time-series data and multivariate statistics.

PubMed

Kim, Tae-Wook; Kim, Dongseon; Baek, Seung Ho; Kim, Young Ok

2015-01-15

The successful management of sustainable coastal environments that are beneficial to both humans and marine ecosystems requires knowledge about factors that are harmful to such environments. Here, we investigated seawater nutrient and carbon parameters between 2010 and 2012 in Kwangyang Bay, Korea, a coastal environment that has been exposed to intensive anthropogenic activities. The data were analyzed using cluster and factor analysis. We found that the biogeochemical cycles of nutrients and carbon were determined by river discharge into the bay and biological activity. However, the impacts of these factors varied both spatially and seasonally. During the past 10 years, nutrient loads from the river and industrial complexes to the bay have decreased. The impacts of this decrease are visible in the phosphate concentration, which has fallen to a third of its initial value. We also examined the potential role of atmospheric nitrogen deposition in nitrogen cycling in the study area. Copyright © 2014 Elsevier Ltd. All rights reserved.

The study of the impact for social culture toward the planning of reclamation for Benoa Bay in Bali

NASA Astrophysics Data System (ADS)

Ardhana, I. Putu Gede; Farhaeni, Mutria

2017-05-01

This study aims to examine the impact of social culture on the planning of reclamation for Benoa Bay in Bali. This study began with a discussion about the process to get a license for the reclamation of Benoa Bay, and then discussed the impact on social culture, especially for the contamination of traditional holy places (places where are used for Balinese Hindus' religious rituals and customs). This study used a descriptive method with regulation, legislative, and literature approaches. The result of this study was recorded, analyzed, interpreted and compiled in the form of a paper. From the results of this study, the authors concluded that the process to get a license ignored the environment, and paid no attention to socialization and the communication of information about the developmental planning of reclamation in Benoa Bay in Bali. From the aspect of social culture, the traditional holy places for Balinese Hindus will be contaminated.

Monitoring population status of sea otters (Enhydra lutris) in Glacier Bay National Park and Preserve, Alaska: options and considerations

USGS Publications Warehouse

Esslinger, George G.; Esler, Daniel N.; Howlin, S.; Starcevich, L.A.

2015-06-25

After many decades of absence from southeast Alaska, sea otters (Enhydra lutris) are recolonizing parts of their former range, including Glacier Bay, Alaska. Sea otters are well known for structuring nearshore ecosystems and causing community-level changes such as increases in kelp abundance and changes in the size and number of other consumers. Monitoring population status of sea otters in Glacier Bay will help park researchers and managers understand and interpret sea otter-induced ecosystem changes relative to other sources of variation, including potential human-induced impacts such as ocean acidification, vessel disturbance, and oil spills. This report was prepared for the National Park Service (NPS), Southeast Alaska Inventory and Monitoring Network following a request for evaluation of options for monitoring sea otter population status in Glacier Bay National Park and Preserve. To meet this request, we provide a detailed consideration of the primary method of assessment of abundance and distribution, aerial surveys, including analyses of power to detect interannual trends and designs to reduce variation around annual abundance estimates. We also describe two alternate techniques for evaluating sea otter population status—(1) quantifying sea otter diets and energy intake rates, and (2) detecting change in ages at death. In addition, we provide a brief section on directed research to identify studies that would further our understanding of sea otter population dynamics and effects on the Glacier Bay ecosystem, and provide context for interpreting results of monitoring activities.

Using Remotely Sensed Data and Watershed and Hydrodynamic Models to Evaluate the Effects of Land Cover Land Use Change on Aquatic Ecosystems in Mobile Bay, AL

NASA Technical Reports Server (NTRS)

Al-Hamdan, Mohammad; Estes, Maurice G., Jr.; Judd, Chaeli; Woodruff, Dana; Ellis, Jean; Quattrochi, Dale; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

2012-01-01

Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land cover land use (LCLU) change in the two counties surrounding Mobile Bay (Mobile and Baldwin) on SAV stressors and controlling factors (temperature, salinity, and sediment) in the Mobile Bay estuary. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for LCLU scenarios in 1948, 1992, 2001, and 2030. Remotely sensed Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 LCLU scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the estuary. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid throughout Mobile Bay and adjacent estuaries. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to LCLU driven flow changes with the restoration potential of SAVs. Data products and results are being integrated into NOAA s EcoWatch and Gulf of Mexico Data Atlas online systems for dissemination to coastal resource managers and stakeholders. Objective 1: Develop and utilize Land Use scenarios for Mobile and Baldwin Counties, AL as input to models to predict the affects on water properties (temperature,salinity,)for Mobile Bay through 2030. Objective 2: Evaluate the impact of land use change on seagrasses and SAV in Mobile Bay. Hypothesis: Urbanization will significantly increase surface flows and impact salinity and temperature variables that effect seagrasses and SAVs.

388. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

388. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; SUSPENDED STRUCTURE; SIDE SPAN TRUSSES AT ANCHORAGES; CONTRACT NO. 6; DRAWING NO. 40 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Deep Borehole Instrumentation Along San Francisco Bay Bridges - 2000

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

Hutchings, L.; Kasameyer, P.; Turpin, C.

2000-03-01

This is a progress report on the Bay Bridges downhole network. Between 2 and 8 instruments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges in San Francisco Bay, California. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty-one sensor packages at fifteen sites. The downhole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 731 accelerometers, and is capable of recording a micro g from local Mmore » = 1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes. Preliminary results on phasing across the Bay Bridge, up and down hole wave amplification at Yerba Buena Island, and sensor orientation analysis are presented. Events recorded and located during 1999 are presented. Also, a senior thesis on the deep structure of the San Francisco Bay beneath the Bay Bridge is presented as an addendum.« less

Status and needs for seismic instrumentation of structures along the Hayward fault

USGS Publications Warehouse

Kalkan, Erol; Çelebi, Mehmet

2008-01-01

The inventory of structures in heavily urbanized communities within the greater San Francisco (SF) Bay area that will experience strong ground motions from the rupture of the Hayward Fault includes a variety of types of recent and older structures built with a variety of materials and to different code standards. Those who remember the effects of the 1989 Loma Prieta earthquake on structures in the San Francisco Bay area also remember the collapse of one upper-deck segment of the Bay Bridge that halted transportation for approximately five weeks. In order to understand how these structures respond to earthquake motions and to improve building practices to resist these strong motions it is imperative that owners of these structures as well as governmental organizations acquire shaking response data from instrumented (or yet to be instrumented structures) during the forecast events. Within California, such data are acquired mainly by California Geological Survey and the United States Geological Survey. A small number of private owners contribute to this effort. The inventory of existing instrumented structures is much less than 0.1% of the total, and thus statistically it is not sufficient. For example, some of the existing important regular or lifeline structures are not instrumented(e.g. Bart Trans-Bay Tunnel, many segments of the Bart elevated structures in the proximity of the Hayward Fault, the yet to be completed eastern part of San Francisco Bay Bridge, Hetch-Hetchy pipeline system crossing the Hayward Fault)even though attempts and proposals have been developed to do so in the past. This paper presents a critical assessment of the status quo and the future needs for instrumentation of structures in the greater SF Bay area that includes the Hayward Fault. There are many new attempts and successes in instrumentation of structures in this region. Two successful examples are provided here, but more needs to be done. The paper does not present new research results; hence, it should be considered to be a “tutorial” paper.

Importance of storm events in controlling ecosystem structure and function in a Florida Gulf Coast estuary

USGS Publications Warehouse

Davis, S. E.; Cable, J.E.; Childers, D.L.; Coronado-Molina, C.; Day, J.W.; Hittle, C.D.; Madden, C.J.; Reyes, E.; Rudnick, D.; Sklar, F.

2004-01-01

From 8/95 to 2/01, we investigated the ecological effects of intra- and inter-annual variability in freshwater flow through Taylor Creek in southeastern Everglades National Park. Continuous monitoring and intensive sampling studies overlapped with an array of pulsed weather events that impacted physical, chemical, and biological attributes of this region. We quantified the effects of three events representing a range of characteristics (duration, amount of precipitation, storm intensity, wind direction) on the hydraulic connectivity, nutrient and sediment dynamics, and vegetation structure of the SE Everglades estuarine ecotone. These events included a strong winter storm in November 1996, Tropical Storm Harvey in September 1999, and Hurricane Irene in October 1999. Continuous hydrologic and daily water sample data were used to examine the effects of these events on the physical forcing and quality of water in Taylor Creek. A high resolution, flow-through sampling and mapping approach was used to characterize water quality in the adjacent bay. To understand the effects of these events on vegetation communities, we measured mangrove litter production and estimated seagrass cover in the bay at monthly intervals. We also quantified sediment deposition associated with Hurricane Irene's flood surge along the Buttonwood Ridge. These three events resulted in dramatic changes in surface water movement and chemistry in Taylor Creek and adjacent regions of Florida Bay as well as increased mangrove litterfall and flood surge scouring of seagrass beds. Up to 5 cm of bay-derived mud was deposited along the ridge adjacent to the creek in this single pulsed event. These short-term events can account for a substantial proportion of the annual flux of freshwater and materials between the mangrove zone and Florida Bay. Our findings shed light on the capacity of these storm events, especially when in succession, to have far reaching and long lasting effects on coastal ecosystems such as the estuarine ecotone of the SE Everglades.

Late Eocene impacts: Geologic record, correlation, and paleoenvironmental consequences

USGS Publications Warehouse

Poag, C. Wylie; Mankinen, Edward A.; Norris, Richard D.

2003-01-01

We present new magnetostratigraphic and stable isotopic (18C, 13Ccarb) data to help improve correlations among three late Eocene impact craters and their inferred breccia and ejecta deposits. Our analyses also shed light on potential global environmental consequences attributable to the impacts. The new data come from a continuously cored interval of the subsurface Chickahominy Formation, which lies conformably above the Chesapeake Bay impact crater in southeastern Virginia. The new magnetostratigraphic data indicate that the Chesapeake Bay impact took place in Chron C16n. 2n, the same magnetochron that encompasses the late Eocene ejecta layer at Massignano, Italy. This correlation places both the Chesapeake Bay impact and the Massignano ejecta at ~35.6 Ma, and resolves a previous miscorrelation between these two sites based on planktonic foraminifera and calcareous nannofossils. The new magnetostratigraphic correlations also suggest that the published magnetostratigraphic framework for ejecta-bearing late Eocene strata ar ODP Site 689B (Maud Rise) is incorrect, due to an incomplete section.New 18C data (single species of benthic foraminifera) from the same Chickahominy section ar Chesapeake Bay indicate that successional intervals of warm oceanic bottom-water may be characteristic of the late Eocene. We infer that the warm intervals correlate with successive episodes of greenhouse warming, triggered in part by a comer shower, which produced the Chesapeake Bay, Toms Canyon, Popigai, and presumably additional (as yet undiscovered) late Eocene impact craters. We also demonstrate that a marked negative execution of 13Ccarb persists through the upper half of the Chickahominy Formation. This excursion, also recorded at Massigno, at Bath Cliff, Barbados, and at other widespread localities in the world ocean, may be additional evidence of global-scale, long-term environmental disturbances related to the bolide impacts. As such, this  13C signal may be useful for global subdivision of the late Eocene stratigraphic record.

The increasing impact of food production on nutrient export by rivers to the Bay of Bengal 1970-2050.

PubMed

Sattar, Abdus; Kroeze, Carolien; Strokal, Maryna

2014-03-15

The objective of this study is to assess the impact of food production on river export of nutrients to the coastal waters of the Bay of Bengal in the past (1970 and 2000) and the future (2030 and 2050), and the associated potential for coastal eutrophication. We model nutrient export from land to sea, using the Global NEWS (Nutrient Export from WaterSheds) approach. We calculate increases in river export of N and P over time. Agricultural sources account for about 70-80% of the N and P in rivers. The coastal eutrophication potential is high in the Bay. In 2000, nutrient discharge from about 85% of the basin area of the Bay drains into coastal seas contributes to the risk of coastal eutrophication. By 2050, this may be 96%. We also present an alternative scenario in which N and P inputs to the Bay are 20-35% lower than in the baseline. Copyright © 2014 Elsevier Ltd. All rights reserved.

Coastal and wetland ecosystems of the Chesapeake Bay watershed: Applying palynology to understand impacts of changing climate, sea level, and land use

USGS Publications Warehouse

Willard, Debra A.; Bernhardt, Christopher E.; Hupp, Cliff R.; Newell, Wayne L.

2015-01-01

The mid-Atlantic region and Chesapeake Bay watershed have been influenced by fluctuations in climate and sea level since the Cretaceous, and human alteration of the landscape began ~12,000 years ago, with greatest impacts since colonial times. Efforts to devise sustainable management strategies that maximize ecosystem services are integrating data from a range of scientific disciplines to understand how ecosystems and habitats respond to different climatic and environmental stressors. Palynology has played an important role in improving understanding of the impact of changing climate, sea level, and land use on local and regional vegetation. Additionally, palynological analyses have provided biostratigraphic control for surficial mapping efforts and documented agricultural activities of both Native American populations and European colonists. This field trip focuses on sites where palynological analyses have supported efforts to understand the impacts of changing climate and land use on the Chesapeake Bay ecosystem.

Assessing climate change impacts on winter cover crop nitrate uptake efficiency on the coastal plain of the Chesapeake Bay watershed using the SWAT model

USDA-ARS?s Scientific Manuscript database

Climate change is expected to exacerbate water quality degradation in the Chesapeake Bay watershed (CBW). Winter cover crops (WCCs) have been widely implemented in this region owing to their high effectiveness at reducing nitrate loads. However, little is known about climate change impacts on the ef...

Human and riverine impacts on the dynamics of seawater nutrient and carbon parameters in Kwangyang Bay, South Korea

NASA Astrophysics Data System (ADS)

Kim, Tae-Wook; Kim, Dongseon; Baek, Seung Ho; Kim, Young Ok

2015-04-01

We investigated seawater nutrient and carbon parameters in Kwangyang Bay, South Korea, which has been exposed to significant human influences, in each core month of four seasons for between 2010 and 2012. The survey data were analyzed using multivariate statistics analysis (cluster and factor analysis). As a result, we found that the Seomjin River (the fifth largest river in South Korea) and biological activity, including phytoplankton photosynthesis and bacterial decomposition, were the main factors determining the overall water quality of the bay. However, the impacts of these factors varied both spatially and seasonally, because the factors were linked with the geographical environments and seasonal variations in freshwater discharge. In particular, the Seomjin River was primarily responsible for nitrate, silicate, total alkalinity, and dissolved inorganic carbon, and exhibited a significant impact in the summer. During the past 10 years, nutrient loads from the river and industrial complexes to the bay have decreased. The impacts of this decrease are visible in the phosphate concentration, which has fallen to a third of its initial value. We also examined the potential role of atmospheric nitrogen deposition in nitrogen cycling in the study area.

Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation Stressors in Mobile Bay

NASA Technical Reports Server (NTRS)

Al-Hamdan, Mohammad; Estes, Maurice G., Jr.; Quattrochi, Dale; Thom, Ronald; Woodruff, Dana; Judd, Chaeli; Ellis, Jean; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

2009-01-01

Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land use change in Mobile and Baldwin counties on SAV stressors and controlling factors (temperature, salinity, and sediment) in Mobile Bay. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use scenarios in 1948, 1992, 2001, and 2030. Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the Bay. Theses results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid with four vertical profiles throughout Mobile Bay. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to land use driven flow changes with the restoration potential of SAVs.

Continuous resistivity profiling and seismic-reflection data collected in April 2010 from Indian River Bay, Delaware

USGS Publications Warehouse

Cross, V.A.; Bratton, J.F.; Michael, H.A.; Kroeger, K.D.; Green, Adrian; Bergeron, Emile M.

2014-01-01

A geophysical survey to delineate the fresh-saline groundwater interface and associated sub-bottom sedimentary structures beneath Indian River Bay, Delaware, was carried out in April 2010. This included surveying at higher spatial resolution in the vicinity of a study site at Holts Landing, where intensive onshore and offshore studies were subsequently completed. The total length of continuous resistivity profiling (CRP) survey lines was 145 kilometers (km), with 36 km of chirp seismic lines surveyed around the perimeter of the bay. Medium-resolution CRP surveying was performed using a 50-meter streamer in a baywide grid. Results of the surveying and data inversion showed the presence of many buried paleochannels beneath Indian River Bay that generally extended perpendicular from the shoreline in areas of modern tributaries, tidal creeks, and marshes. An especially wide and deep paleochannel system was imaged in the southeastern part of the bay near White Creek. Many paleochannels also had high-resistivity anomalies corresponding to low-salinity groundwater plumes associated with them, likely due to the presence of fine-grained estuarine mud and peats in the channel fills that act as submarine confining units. Where present, these units allow plumes of low-salinity groundwater that was recharged onshore to move beyond the shoreline, creating a complex fresh-saline groundwater interface in the subsurface. The properties of this interface are important considerations in construction of accurate coastal groundwater flow models. These models are required to help predict how nutrient-rich groundwater, recharged in agricultural watersheds such as this one, makes its way into coastal bays and impacts surface-water quality and estuarine ecosystems.

Assessing the impacts of salinity and nutrient stress to Ruppia ...

EPA Pesticide Factsheets

Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have disappeared due to infilling, pollution and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, Ruppia maritima has colonized an area on the northern shore historically dominated by Zostera marina. Ruppia is extremely salinity tolerant, and may also be more nutrient tolerant than Zostera. To test this hypothesis 6-week microcosm experiments were conducted in the summers of 2014 and 2015. Microcosms were renewed daily to simulate tidal flushing and the water column was dosed with a 15N tracer for the first week of the experiments. In the 2014 microcosm experiment two salinity (20, 30 ppt) and four nutrient (0, 5, 10, 30 µM inorganic N) levels were used to test the species’ relative tolerance. This experiment yielded structurally significant results for Ruppia but no significant differences were detected for Zostera. In 2015 this experiment was performed for a second time with lower salinity (5, 30 ppt) and higher nutrients (0, 30, 100, 300, 1000 µM inorganic N) in order to determine Zostera’s tolerance to nutrient and salinity stress and confirm the previously observed Ruppia results. Both species had significant structural responses to the nutrient and salinity variables. Isotopic analysis run on above-ground tissue indicated that with increasing nutrient levels δ15N in the seagrass shoots increased, suggesting that nutrients

Structure and variability of symbiotic assemblages associated with feather stars (Crinoidea: Comatulida) Himerometra robustipinna

NASA Astrophysics Data System (ADS)

Britayev, T. A.; Beksheneva, L. F.; Deart, Yu. V.; Mekhova, E. S.

2016-09-01

The paper considers the influence of the geographical position and local conditions on the structure and abundance of symbiotic communities (SCs) associated with the crinoid Himerometra robustipinna. Two water areas at the coast of Vietnam (Nhatrang Bay and the Anthoy Archipelago; our data), Hansa Bay (Papua, New Guinea; Deyen et al., 2006), and the Great Barrier Reef (Australia; Fabricius and Dale, 1993) were compared. We found a similarity in the contribution from the main taxa to the structure of SCs between geographically distant water areas—Nhatrang Bay, Hansa Bay, and the Great Barrier Reef (GBR)—and strong differences between the two Vietnamese water areas. A possible reason for the differences in the SC structure in these water areas is not their geographical location, but the environmental conditions, which are more stable in the seaward part of Nhatrang Bay and less stable in the Anthoy Archipelago. The abundances of symbionts in the water areas of the coast of Vietnam are similar to each other and strongly different from Hansa Bay and the GBR. We suppose that a factor regulating the abundance of symbionts is their consumption by predatory fishes. A low abundance of fishes in the area of active coastal fishery (the coast of Vietnam) makes possible the existence of SCs with a high abundance. In Hansa Bay and the GBR where fishery pressure is low, a high number of predators leads to a low abundance of symbionts.

Full-Scale Test and Analysis Results of a PRSEUS Fuselage Panel to Assess Damage Containment Features

NASA Technical Reports Server (NTRS)

Bergan, Andrew; Bakuckas, John G., Jr.; Lovejoy, Andrew; Jegley, Dawn; Linton, Kim; Neal, Bert; Korkosz, Gregory; Awerbuch, Jonathan; Tan, Tein-Min

2012-01-01

Integrally stitched composite technology is an area that shows promise in enhancing the structural integrity of aircraft and aerospace structures. The most recent generation of this technology is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. The goal of the PRSEUS concept relevant to this test is to provide damage containment capability for composite structures while reducing overall structural weight. The National Aeronautics and Space Administration (NASA), the Federal Aviation Administration (FAA), and The Boeing Company have partnered in an effort to assess the damage containment features of a full-scale curved PRSEUS panel using the FAA Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility. A single PRSEUS test panel was subjected to axial tension, internal pressure, and combined axial tension and internal pressure loads. The test results showed excellent performance of the PRSEUS concept. No growth of Barely Visible Impact Damage (BVID) was observed after ultimate loads were applied. With a two-bay notch severing the central stringer, damage was contained within the two-bay region well above the required limit load conditions. Catastrophic failure was well above the ultimate load level. Information describing the test panel and procedure has been previously presented, so this paper focuses on the experimental procedure, test results, nondestructive inspection results, and preliminary test and analysis correlation.

View south; interior structural detail at column A13 south bay ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View south; interior structural detail at column A13 south bay - Naval Base Philadelphia-Philadelphia Naval Shipyard, Foundry-Propeller Shop, North of Porter Avenue, west of Third Street West, Philadelphia, Philadelphia County, PA

FAST Mast Structural Response to Axial Loading: Modeling and Verification

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Elliott, Kenny B.; Templeton, Justin D.; Song, Kyongchan; Rayburn, Jeffery T.

2012-01-01

The International Space Station s solar array wing mast shadowing problem is the focus of this paper. A building-block approach to modeling and analysis is pursued for the primary structural components of the solar array wing mast structure. Starting with an ANSYS (Registered Trademark) finite element model, a verified MSC.Nastran (Trademark) model is established for a single longeron. This finite element model translation requires the conversion of several modeling and analysis features for the two structural analysis tools to produce comparable results for the single-longeron configuration. The model is then reconciled using test data. The resulting MSC.Nastran (Trademark) model is then extended to a single-bay configuration and verified using single-bay test data. Conversion of the MSC. Nastran (Trademark) single-bay model to Abaqus (Trademark) is also performed to simulate the elastic-plastic longeron buckling response of the single bay prior to folding.

New Observations at the Slate Islands Impact Structure, Lake Superior

NASA Technical Reports Server (NTRS)

Dressler, B. O.; Sharpton, V. L.; Schnieders, B.; Scott, J.

1995-01-01

Slate Islands, a group of 2 large and several small islands, is located in northern Lake Superior, approximately 10 km south of Terrace Bay. Shatter cones, breccias and shock metamorphic features provide evidence that the Slate Islands Structure was formed as a result of asteroid or comet impact. Most of the island group is believed to represent the central uplift of a complex impact crater. The structure possibly has a diameter of about 32 km. For Sage (1978, 1991) shock metamorphic features, shatter cones and pervasive rock brecciation are the results of diatreme activity. The present investigations represent the second year of a co-operative study of the Lunar and Planetary Institute, Houston, Texas and the Field Services Section (Northwest) of the Ontario Geological Survey. The objective of this investigation is to come to a better understanding of the formation of mid-size impact structures on Earth and the planets of the solar system. Impact processes played a fundamental role in the formation of the planets and the evolution of life on Earth. Meteorite and comet impacts are not a phenomenon of the past. Last year, more than 20 pieces of the Shoemaker-Levy 9 impacted on Jupiter and the Tunguska comet impacted in Siberia in the early years of this century. The study of impact processes is a relatively young part of geoscience and much is still to be learnt by detailed field and laboratory investigations. The State Islands Structure has been selected for the present detailed investigations because of the excellent shoreline outcrops of rock units related to the impact. The structure is a complex impact crater that has been eroded so that important lithological and structural elements are exposed. We know of no other mid-size terrestrial impact structure with equal or better exposures. In this publication we present preliminary results of our 1994 and 1995 field and laboratory investigations. We have tentatively identified a few impact melt and a considerable number of suevite occurrences.

Impact of small-scale structures on estuarine circulation

NASA Astrophysics Data System (ADS)

Liu, Zhuo; Zhang, Yinglong J.; Wang, Harry V.; Huang, Hai; Wang, Zhengui; Ye, Fei; Sisson, Mac

2018-05-01

We present a novel and challenging application of a 3D estuary-shelf model to the study of the collective impact of many small-scale structures (bridge pilings of 1 m × 2 m in size) on larger-scale circulation in a tributary (James River) of Chesapeake Bay. We first demonstrate that the model is capable of effectively transitioning grid resolution from 400 m down to 1 m near the pilings without introducing undue numerical artifact. We then show that despite their small sizes and collectively small area as compared to the total channel cross-sectional area, the pilings exert a noticeable impact on the large-scale circulation, and also create a rich structure of vortices and wakes around the pilings. As a result, the water quality and local sedimentation patterns near the bridge piling area are likely to be affected as well. However, when evaluating over the entire waterbody of the project area, the near field effects are weighed with the areal percentage which is small compared to that for the larger unaffected area, and therefore the impact on the lower James River as a whole becomes relatively insignificant. The study highlights the importance of the use of high resolution in assessing the near-field impact of structures.

Potential climate change impacts on a tropical estuary: Hilo Bay, Hawaii

NASA Astrophysics Data System (ADS)

Adolf, J.; LaPinta, J.; Marusek, J.; Pascoe, K.; Pugh, A.

2016-02-01

Hilo Bay is a tropical estuarine ecosystem on the northeast (windward) coast of Hawai`i Island that is potentially vulnerable to climate change effects mediated through elevated water temperatures and/or changing rainfall patterns that impact river and groundwater fluxes. Here, we document trends in water temperature, river flow and phytoplankton dynamics in Hilo Bay. Hilo Bay is fed by two major rivers, Wailuku and Honoli`i, both of which have shown long term declines in output over their 85 and 38 year monitoring periods (USGS), respectively. Time series of groundwater inputs to Hilo Bay do not exist, but the average estimated rate rivals that of average river inputs. Daily average Hilo Bay water temperatures have increased at a rate of 0.35 degrees C per year (p < 0.001) since measurement by the Hilo Bay water quality buoy began in 2010, with the warmest temperatures on record recorded Sept 2015. Salinity did not show a trend over this same time period. Phytoplankton showed a pronounced seasonal cycle in Hilo Bay with a long term average of 3.7 mg m-3 and dominance by diatoms that exploit the co-availability of silica and nitrate in this environment. On shorter time scales of days to < 1 week, flood events dramatically reduce Hilo Bay salinity, temperature and phytoplankton biomass. Coincidental atmospheric warming, SST warming in the adjacent North Pacific ocean, and declining river flows will likely work together to result in elevated SST in Hilo Bay if observed trends continue. The El Nino event that started this year is expected to exacerbate this warming through reduce river flow and warmer regional SST.

Patterns of alien plant invasion across coastal bay areas in southern China

Treesearch

Hai Ren; Qinfeng Guo; Hong Liu; Jing Li; Qianmei Zhang; Hualin Xu; Fanghong Xu

2014-01-01

An understanding of the ways in which levels of invasions by alien species are correlated with environmental factors is helpful to manage the negative impacts of these invasive species. Two tropical coastal areas in South China, Shenzhen Bay and Leizhou Bay, are national nature reserves, but they are threatened by invasive plants. Here, we investigated the level of...

Identifying habitats at risk: simple models can reveal complex ecosystem dynamics.

PubMed

Maxwell, Paul S; Pitt, Kylie A; Olds, Andrew D; Rissik, David; Connolly, Rod M

2015-03-01

The relationship between ecological impact and ecosystem structure is often strongly nonlinear, so that small increases in impact levels can cause a disproportionately large response in ecosystem structure. Nonlinear ecosystem responses can be difficult to predict because locally relevant data sets can be difficult or impossible to obtain. Bayesian networks (BN) are an emerging tool that can help managers to define ecosystem relationships using a range of data types from comprehensive quantitative data sets to expert opinion. We show how a simple BN can reveal nonlinear dynamics in seagrass ecosystems using ecological relationships sourced from the literature. We first developed a conceptual diagram by cataloguing the ecological responses of seagrasses to a range of drivers and impacts. We used the conceptual diagram to develop a BN populated with values sourced from published studies. We then applied the BN to show that the amount of initial seagrass biomass has a mitigating effect on the level of impact a meadow can withstand without loss, and that meadow recovery can often require disproportionately large improvements in impact levels. This mitigating effect resulted in the middle ranges of impact levels having a wide likelihood of seagrass presence, a situation known as bistability. Finally, we applied the model in a case study to identify the risk of loss and the likelihood of recovery for the conservation and management of seagrass meadows in Moreton Bay, Queensland, Australia. We used the model to predict the likelihood of bistability in 23 locations in the Bay. The model predicted bistability in seven locations, most of which have experienced seagrass loss at some stage in the past 25 years providing essential information for potential future restoration efforts. Our results demonstrate the capacity of simple, flexible modeling tools to facilitate collation and synthesis of disparate information. This approach can be adopted in the initial stages of conservation programs as a low-cost and relatively straightforward way to provide preliminary assessments of.nonlinear dynamics in ecosystems.

Association between degradation of pharmaceuticals and endocrine-disrupting compounds and microbial communities along a treated wastewater effluent gradient in Lake Mead

USGS Publications Warehouse

Blunt, Susanna M.; Sackett, Joshua D.; Rosen, Michael R.; Benotti, Mark J.; Trenholm, Rebecca A.; Vanderford, Brett J.; Hedlund, Brian P.; Moser, Duane P.

2018-01-01

The role of microbial communities in the degradation of trace organic contaminants in the environment is little understood. In this study, the biotransformation potential of 27 pharmaceuticals and endocrine-disrupting compounds was examined in parallel with a characterization of the native microbial community in water samples from four sites variously impacted by urban run-off and wastewater discharge in Lake Mead, Nevada and Arizona, USA. Samples included relatively pristine Colorado River water at the upper end of the lake, nearly pure tertiary-treated municipal wastewater entering via the Las Vegas Wash, and waters of mixed influence (Las Vegas Bay and Boulder Basin), which represented a gradient of treated wastewater effluent impact. Microbial diversity analysis based on 16S rRNA gene censuses revealed the community at this site to be distinct from the less urban-impacted locations, although all sites were similar in overall diversity and richness. Similarly, Biolog EcoPlate assays demonstrated that the microbial community at Las Vegas Wash was the most metabolically versatile and active. Organic contaminants added as a mixture to laboratory microcosms were more rapidly and completely degraded in the most wastewater-impacted sites (Las Vegas Wash and Las Vegas Bay), with the majority exhibiting shorter half-lives than at the other sites or in a bacteriostatic control. Although the reasons for enhanced degradation capacity in the wastewater-impacted sites remain to be established, these data are consistent with the acclimatization of native microorganisms (either through changes in community structure or metabolic regulation) to effluent-derived trace contaminants. This study suggests that in urban, wastewater-impacted watersheds, prior exposure to organic contaminants fundamentally alters the structure and function of microbial communities, which in turn translates into greater potential for the natural attenuation of these compounds compared to more pristine sites.

Association between degradation of pharmaceuticals and endocrine-disrupting compounds and microbial communities along a treated wastewater effluent gradient in Lake Mead.

PubMed

Blunt, Susanna M; Sackett, Joshua D; Rosen, Michael R; Benotti, Mark J; Trenholm, Rebecca A; Vanderford, Brett J; Hedlund, Brian P; Moser, Duane P

2018-05-01

The role of microbial communities in the degradation of trace organic contaminants in the environment is little understood. In this study, the biotransformation potential of 27 pharmaceuticals and endocrine-disrupting compounds was examined in parallel with a characterization of the native microbial community in water samples from four sites variously impacted by urban run-off and wastewater discharge in Lake Mead, Nevada and Arizona, USA. Samples included relatively pristine Colorado River water at the upper end of the lake, nearly pure tertiary-treated municipal wastewater entering via the Las Vegas Wash, and waters of mixed influence (Las Vegas Bay and Boulder Basin), which represented a gradient of treated wastewater effluent impact. Microbial diversity analysis based on 16S rRNA gene censuses revealed the community at this site to be distinct from the less urban-impacted locations, although all sites were similar in overall diversity and richness. Similarly, Biolog EcoPlate assays demonstrated that the microbial community at Las Vegas Wash was the most metabolically versatile and active. Organic contaminants added as a mixture to laboratory microcosms were more rapidly and completely degraded in the most wastewater-impacted sites (Las Vegas Wash and Las Vegas Bay), with the majority exhibiting shorter half-lives than at the other sites or in a bacteriostatic control. Although the reasons for enhanced degradation capacity in the wastewater-impacted sites remain to be established, these data are consistent with the acclimatization of native microorganisms (either through changes in community structure or metabolic regulation) to effluent-derived trace contaminants. This study suggests that in urban, wastewater-impacted watersheds, prior exposure to organic contaminants fundamentally alters the structure and function of microbial communities, which in turn translates into greater potential for the natural attenuation of these compounds compared to more pristine sites. Copyright © 2017. Published by Elsevier B.V.

Integral Airframe Structures (IAS): Validated Feasibility Study of Integrally Stiffened Metallic Fuselage Panels for Reducing Manufacturing Costs

NASA Technical Reports Server (NTRS)

Munroe, J.; Wilkins, K.; Gruber, M.; Domack, Marcia S. (Technical Monitor)

2000-01-01

The Integral Airframe Structures (IAS) program investigated the feasibility of using "integrally stiffened" construction for commercial transport fuselage structure. The objective of the program was to demonstrate structural performance and weight equal to current "built-up" structure with lower manufacturing cost. Testing evaluated mechanical properties, structural details, joint performance, repair, static compression, and two-bay crack residual strength panels. Alloys evaluated included 7050-T7451 plate, 7050-T74511 extrusion, 6013-T6511x extrusion, and 7475-T7351 plate. Structural performance was evaluated with a large 7475-T7351 pressure test that included the arrest of a two-bay longitudinal crack, and a measure of residual strength for a two-bay crack centered on a broken frame. Analysis predictions for the two-bay longitudinal crack panel correlated well with the test results. Analysis activity conducted by the IAS team strongly indicates that current analysis tools predict integral structural behavior as accurately as built-up structure. The cost study results indicated that, compared to built-up fabrication methods, high-speed machining structure from aluminum plate would yield a recurring cost savings of 61%. Part count dropped from 78 individual parts on a baseline panel to just 7 parts for machined IAS structure.

78 FR 46813 - Safety Zone; Evening on the Bay Fireworks; Sturgeon Bay, WI

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

... alter the budget of any grant or loan recipients, and will not raise any novel legal or policy issues... Captain of the Port. 2. Impact on Small Entities Under the Regulatory Flexibility Act (5 U.S.C. 601-612), we have considered the impact of this rule on small entities. The Coast Guard certifies under 5 U.S.C...

Help From Above For Bay Waters

EPA Pesticide Factsheets

Actions being taken by a Hopewell, VA. plant as a result of a major EPA Clean Air Act settlement will significantly reduce nitrogen pollution that falls from the atmosphere and impacts the Chesapeake Bay and local waters

Numerical modeling of general circulation, thermohaline structure, and residence time in Gorgan Bay, Iran

NASA Astrophysics Data System (ADS)

Ranjbar, Mohammad Hassan; Hadjizadeh Zaker, Nasser

2018-01-01

Gorgan Bay is a semi-enclosed basin located in the southeast of the Caspian Sea, Iran. The bay is recognized as a resting place for migratory birds as well as a spawning habitat for native fish. However, apparently, no detailed research on its physical processes has previously been conducted. In this study, a 3D coupled hydrodynamic and solute transport model was used to investigate general circulation, thermohaline structure, and residence time in Gorgan Bay. Model outputs were validated against a set of field observations. Bottom friction and attenuation coefficient of light intensity were tuned in order to achieve optimum agreement with the observations. Results revealed that, due to the interaction between bathymetry and prevailing winds, a barotropic double-gyre circulation, dominating the general circulation, existed during all seasons in Gorgan Bay. Furthermore, temperature and salinity fluctuations in the bay were seasonal, due to the seasonal variability of atmospheric fluxes. Results also indicated that under the prevailing winds, the domain-averaged residence time in Gorgan Bay would be approximately 95 days. The rivers discharging into Gorgan Bay are considered as the main sources of nutrients in the bay. Since their mouths are located in the area with a residence time of over 100 days, Gorgan Bay could be at risk of eutrophication; it is necessary to adopt preventive measures against water quality degradation.

A numerical model investigation of the impacts of Hurricane Sandy on water level variability in Great South Bay, New York

USGS Publications Warehouse

Bennett, Vanessa C. C.; Mulligan, Ryan P.; Hapke, Cheryl J.

2018-01-01

Hurricane Sandy was a large and intense storm with high winds that caused total water levels from combined tides and storm surge to reach 4.0 m in the Atlantic Ocean and 2.5 m in Great South Bay (GSB), a back-barrier bay between Fire Island and Long Island, New York. In this study the impact of the hurricane winds and waves are examined in order to understand the flow of ocean water into the back-barrier bay and water level variations within the bay. To accomplish this goal, a high resolution hurricane wind field is used to drive the coupled Delft3D-SWAN hydrodynamic and wave models over a series of grids with the finest resolution in GSB. The processes that control water levels in the back-barrier bay are investigated by comparing the results of four cases that include: (i) tides only; (ii) tides, winds and waves with no overwash over Fire Island allowed; (iii) tides, winds, waves and limited overwash at the east end of the island; (iv) tides, winds, waves and extensive overwash along the island. The results indicate that strong local wind-driven storm surge along the bay axis had the largest influence on the total water level fluctuations during the hurricane. However, the simulations allowing for overwash have higher correlation with water level observations in GSB and suggest that island overwash provided a significant contribution of ocean water to eastern GSB during the storm. The computations indicate that overwash of 7500–10,000 m3s−1 was approximately the same as the inflow from the ocean through the major existing inlet. Overall, the model results indicate the complex variability in total water levels driven by tides, ocean storm surge, surge from local winds, and overwash that had a significant impact on the circulation in Great South Bay during Hurricane Sandy.

A numerical model investigation of the impacts of Hurricane Sandy on water level variability in Great South Bay, New York

NASA Astrophysics Data System (ADS)

Bennett, Vanessa C. C.; Mulligan, Ryan P.; Hapke, Cheryl J.

2018-06-01

Hurricane Sandy was a large and intense storm with high winds that caused total water levels from combined tides and storm surge to reach 4.0 m in the Atlantic Ocean and 2.5 m in Great South Bay (GSB), a back-barrier bay between Fire Island and Long Island, New York. In this study the impact of the hurricane winds and waves are examined in order to understand the flow of ocean water into the back-barrier bay and water level variations within the bay. To accomplish this goal, a high resolution hurricane wind field is used to drive the coupled Delft3D-SWAN hydrodynamic and wave models over a series of grids with the finest resolution in GSB. The processes that control water levels in the back-barrier bay are investigated by comparing the results of four cases that include: (i) tides only; (ii) tides, winds and waves with no overwash over Fire Island allowed; (iii) tides, winds, waves and limited overwash at the east end of the island; (iv) tides, winds, waves and extensive overwash along the island. The results indicate that strong local wind-driven storm surge along the bay axis had the largest influence on the total water level fluctuations during the hurricane. However, the simulations allowing for overwash have higher correlation with water level observations in GSB and suggest that island overwash provided a significant contribution of ocean water to eastern GSB during the storm. The computations indicate that overwash of 7500-10,000 m3s-1 was approximately the same as the inflow from the ocean through the major existing inlet. Overall, the model results indicate the complex variability in total water levels driven by tides, ocean storm surge, surge from local winds, and overwash that had a significant impact on the circulation in Great South Bay during Hurricane Sandy.

Using Water Quality Models in Management - A Multiple Model Assessment, Analysis of Confidence, and Evaluation of Climate Change Impacts

NASA Astrophysics Data System (ADS)

Irby, Isaac David

Human impacts on the Chesapeake Bay through increased nutrient run-off as a result of land-use change, urbanization, and industrialization, have resulted in a degradation of water quality over the last half-century. These direct impacts, compounded with human-induced climate changes such as warming, rising sea-level, and changes in precipitation, have elevated the conversation surrounding the future of water quality in the Bay. The overall goal of this dissertation project is to use a combination of models and data to better understand and quantify the impact of changes in nutrient loads and climate on water quality in the Chesapeake Bay. This research achieves that goal in three parts. First, a set of eight water quality models is used to establish a model mean and assess model skill. All models were found to exhibit similar skill in resolving dissolved oxygen concentrations as well as a number of dissolved oxygen-influencing variables (temperature, salinity, stratification, chlorophyll and nitrate) and the model mean exhibited the highest individual skill. The location of stratification within the water column was found to be a limiting factor in the models' ability to adequately simulate habitat compression resulting from low-oxygen conditions. Second, two of the previous models underwent the regulatory Chesapeake Bay pollution diet mandated by the Environmental Protection Agency. Both models exhibited a similar relative improvement in dissolved oxygen concentrations as a result of the reduction of nutrients stipulated in the pollution diet. A Confidence Index was developed to identify the locations of the Bay where the models are in agreement and disagreement regarding the impacts of the pollution diet. The models were least certain in the deep part of the upper main stem of the Bay and the uncertainty primarily stemmed from the post-processing methodology. Finally, by projecting the impacts of climate change in 2050 on the Bay, the potential success of the pollution diet in light of future projections for air temperature, sea level, and precipitation was examined. While a changing climate will reduce the ability of the nutrient reduction to improve oxygen concentrations, that effect is trumped by the improvements in dissolved oxygen stemming from the pollution diet itself. However, climate change still has the potential to cause the current level of nutrient reduction to be inadequate. This is primarily due to the fact that low-oxygen conditions are predicted to start one week earlier, on average, in the future, with the primary changes resulting from the increase in temperature. Overall, this research lends an increased degree of confidence in the water quality modeling of the potential impact of the Chesapeake Bay pollution diet. This research also establishes the efficacy of utilizing a multiple model approach to examining projected changes in water quality while establishing that the pollution diet trumps the impact from climate change. This work will lead directly to advances in scientific understanding of the response of water quality, ecosystem health, and ecological resilience to the impacts of nutrient reduction and climate change.

Analysis of impactor residues in tray clamps from the Long Duration Exposure Facility. Part 2: Clamps from Bay B of the satellite

NASA Technical Reports Server (NTRS)

Bernhard, Ronald P.; Zolensky, Michael E.

1994-01-01

The Long Duration Exposure Facility (LDEF) was placed in low-Earth orbit (LEO) in 1984 and recovered 5.7 years later. The LDEF was host to several individual experiments specifically designed to characterize critical aspects of meteoroid and debris environment in LEO. However, it was realized from the beginning that the most efficient use of the satellite would be to examine the entire surface for impact features. In this regard, particular interest centered on common exposed materials that faced in all LDEF pointing directions. Among the most important of these materials was the tray clamps. Therefore, in an effort to better understand the nature of particulates in LEO and their effects on spacecraft hardware, residues found in impact features on LDEF tray clamp surfaces are being analyzed. This catalog presents all data from clamps from Bay B of the LDEF. NASA Technical Memorandum 104759 has cataloged impacts that occurred on Bay B (published March 1993). Subsequent catalogs will include clamps from succeeding bays of the satellite.

Experimental Results From Stitched Composite Multi-Bay Fuselage Panels Tested Under Uni-Axial Compression

NASA Technical Reports Server (NTRS)

Baker, Donald J.

2004-01-01

The experimental results from two stitched VARTM composite panels tested under uni-axial compression loading are presented. The curved panels are divided by frames and stringers into five or six bays with a column of three bays along the compressive loading direction. The frames are supported at the ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field measurement technique that utilizes a camera-based-stero-vision system was used to record displacements. The panels were loaded in increments to determine the first bay to buckle. Loading was discontinued at limit load and the panels were removed from the test machine for impact testing. After impacting at 20 ft-lbs to 25 ft-lbs of energy with a spherical indenter, the panels were loaded in compression until failure. Impact testing reduced the axial stiffness 4 percent and less than 1 percent. Postbuckled axial panel stiffness was 52 percent and 70 percent of the pre-buckled stiffness.

Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay

NASA Technical Reports Server (NTRS)

Estes, Maurice G.; Al-Hamdan, Mohammed; Thom, Ron; Quattrochi, Dale; Woodruff, Dana; Judd, Chaeli; Ellism Jean; Watson, Brian; Rodriguez, Hugo; Johnson, Hoyt

2009-01-01

There is a continued need to understand how human activities along the northern Gulf of Mexico coast are impacting the natural ecosystems. The gulf coast is experiencing rapid population growth and associated land cover/land use change. Mobile Bay, AL is a designated pilot region of the Gulf of Mexico Alliance (GOMA) and is the focus area of many current NASA and NOAA studies, for example. This is a critical region, both ecologically and economically to the entire United States because it has the fourth largest freshwater inflow in the continental USA, is a vital nursery habitat for commercially and recreational important fisheries, and houses a working waterfront and port that is expanding. Watershed and hydrodynamic modeling has been performed for Mobile Bay to evaluate the impact of land use change in Mobile and Baldwin counties on the aquatic ecosystem. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use Scenarios in 1948, 1992, 2001, and 2030. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on observed trends. All land use scenarios were developed to a common land classification system developed by merging the 1992 and 2001 National Land Cover Data (NLCD). The LSPC model output provides changes in flow, temperature, sediments and general water quality for 22 discharge points into the Bay. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment concentrations on a grid with four vertical profiles throughout the Bay s aquatic ecosystems. The models were calibrated using in-situ data collected at sampling stations in and around Mobile bay. This phase of the project has focused on sediment modeling because of its significant influence on light attenuation which is a critical factor in the health of submerged aquatic vegetation. The impact of land use change on sediment concentrations was evaluated by analyzing the LSPC and EFDC sediment simulations for the four land use scenarios. Such analysis was also performed for storm and non-storm periods. In- situ data of total suspended sediments (TSS) and light attenuation were used to develop a regression model to estimate light attenuation from TSS. This regression model was used to derive marine light attenuation estimates throughout Mobile bay using the EFDC TSS outputs. The changes in sediment concentrations and associated impact on light attenuation in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on seagreasses and Submerged Aquatic Vegetation (SAV) habitat. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of sediments due to land use driven flow changes with the restoration potential of SAVs.

21. DETAIL OF STRUCTURAL BAY ON NORTH ELEVATION OF BUILDING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

21. DETAIL OF STRUCTURAL BAY ON NORTH ELEVATION OF BUILDING 216 (AMMUNITION MAINTENANCE SHOP) IN ASSEMBLY AREA. - Loring Air Force Base, Weapons Storage Area, Northeastern corner of base at northern end of Maine Road, Limestone, Aroostook County, ME

Hydrogeology of Virginia

USGS Publications Warehouse

Nelms, David L.; Harlow, George; Bruce, T. Scott; Bailey, Christopher M.; Sherwood, W. Cullen; Eaton, L. Scott; Powars, David S.

2016-01-01

The hydrogeology of Virginia documented herein is in two parts. Part 1 consists of an overview and description of the hydrogeology within each regional aquifer system in the Commonwealth. Part 2 includes discussions of hydrogeologic research topics of current relevance including: 1. the Chesapeake Bay impact structure, 2. subsidence/compaction in the Coastal Plain, 3. groundwater age and aquifer susceptibility, 4. the occurrence of groundwater at depth in fractured-rock and karst terrains, and 5. hydrologic response of wells to earthquakes around the world.

James Bay

Atmospheric Science Data Center

2013-04-17

article title:  Hudson Bay and James Bay, Canada   ... which scatters more light in the backward direction. This example illustrates how multi-angle viewing can distinguish physical structures ... MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA. Image ...

Studying onshore-offshore fault linkages and landslides in Icy Bay and Taan Fjord to assess geohazards in Southeast Alaska

NASA Astrophysics Data System (ADS)

McCall, N.; Walton, M. A. L.; Gulick, S. P. S.; Haeussler, P. J.; Reece, R.; Saustrup, S.

2016-12-01

In southeast Alaska, the plate boundary where the Yakutat microplate collides with North America has produced large historical earthquakes (i.e., the Mw 8+ 1899 sequence). Despite the seismic potential, the possible source fault systems for these earthquakes have not been imaged with modern methods in Icy Bay. The offshore Pamplona Zone and its eastward onshore extension, the Malaspina Fault, may have played a role in the September 1899 earthquakes. Onshore and offshore mapping indicates that these structures likely connect offshore in Icy Bay. In August 2016 we collected high-resolution (300-1200 Hz) seismic reflection and multibeam bathymetry data to search for evidence of such faults beneath Icy Bay and Taan Fiord. If the Malaspina Fault is found to link with the Pamplona Zone, a rupture could trigger a tsunami impacting the populated regions in southeast Alaska. More recently, on October 17th 2015, nearby Taan Fjord experienced one of the largest non-volcanic landslides recorded in North America. Approximately 200 million metric tons spilled into Taan Fjord creating a tsunami with waves reaching 150m onshore. Using the new data, we are capable of imaging landslide and tsunami deposits in high-resolution. These data give new constraints for onshore-offshore fault systems, giving us new insights into the earthquake and tsunami hazard in southeast Alaska.

Development of the PRSEUS Multi-Bay Pressure Box for a Hybrid Wing Body Vehicle

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Velicki, Alexander

2015-01-01

NASA has created the Environmentally Responsible Aviation Project to explore and document the feasibility, benefits, and technical risk of advanced vehicle configurations and enabling technologies that will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations that have higher lift-to-drag ratios, reduced drag, and lower community noise. Although such novel configurations like the Hybrid Wing Body (HWB) offer better aerodynamic performance as compared to traditional tube-and-wing aircraft, their blended wing shapes also pose significant new design challenges. Developing an improved structural concept that is capable of meeting the structural weight fraction allocated for these non-circular pressurized cabins is the primary obstacle in implementing large lifting-body designs. To address this challenge, researchers at NASA and The Boeing Company are working together to advance new structural concepts like the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), which is an integrally stiffened panel design that is stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. The large-scale multi-bay fuselage test article described in this paper is the final specimen in a building-block test program that was conceived to demonstrate the feasibility of meeting the structural weight goals established for the HWB pressure cabin.

Coral reefs in an urban embayment in Hawaii: a complex case history controlled by natural and anthropogenic stress

NASA Astrophysics Data System (ADS)

Grigg, R. W.

1995-11-01

The effects of natural and anthropogenic stress need to be separated before coral reef ecosystems can be effectively managed. In this paper, a 25 year case history of coral reefs in an urban embayment (Mamala Bay) off Honolulu, Hawaii is described and differences between natural and man-induced stress are distinguished. Mamala Bay is a 30 km long shallow coastal bay bordering the southern (leeward) shore of Oahu and the city of Honolulu in the Hawaiian Islands. During the last 25 years, this area has been hit by two magnitude 5 hurricane events (winds > 240 km/h) generating waves in excess of 7.5 m. Also during this period, two large sewer outfalls have discharged up to 90 million gallons per day (mgd) or (360 × 106 L/day) of point source pollution into the bay. Initially the discharge was raw sewage, but since 1977 it has received advanced primary treatment. Non-point source run-off from the Honolulu watershed also enters the bay on a daily basis. The results of the study show that discharge of raw sewage had a serious but highly localized impact on shallow (˜10 m) reef corals in the bay prior to 1977. After 1977, when treatment was upgraded to the advanced primary level and outfalls were extended to deep water (> 65 m), impacts to reef corals were no longer significant. No measurable effects of either point or non-point source pollution on coral calcification, growth, species composition, diversity or community structure related to pollution can now be detected. Conversely the effects of hurricane waves in 1982 and 1992 together caused major physical destruction to the reefs. In 1982, average coral cover of well-developed offshore reefs dropped from 60-75% to 5-15%. Only massive species in high relief areas survived. Today, recovery is occurring, and notwithstanding major future disturbance events, long-term biological processes should eventually return the coral ecosystems to a more mature successional stage. This case history illustrates the complex nature of the cumulative effects of natural and anthropogenic stress on coral reefs and the need for a long-term data base before the status of a coral reef can be properly interpreted.

The Impact of Special Admissions Programs on General Admissions Policies in Five San Francisco Bay Area Public Institutions of Higher Education 1966-1971.

ERIC Educational Resources Information Center

Alford, Howard Lee

This study researched the impact of special admissions programs on general admission policies in 5 San Francisco Bay area colleges and universities during a period of 5 years ending June 1971. The study was conducted to determine more specifically: (1) what general admissions policies were waived for special admissions students; (2) what was the…

Anthropogenic impacts on meiobenthic Ostracoda (Crustacea) in the moderately polluted Kasado Bay, Seto Inland Sea, Japan, over the past 70 years.

PubMed

Irizuki, Toshiaki; Ito, Hisayo; Sako, Megumi; Yoshioka, Kaoru; Kawano, Shigenori; Nomura, Ritsuo; Tanaka, Yuichiro

2015-02-15

Two sediment cores were obtained from Kasado Bay, a moderate-polluted enclosed bay in Japan, to examine anthropogenic impacts on Ostracoda over the past ca. 70 years. We analyzed ostracode abundance and diversity, grain size, and CHN, and used (210)Pb and (137)Cs as the dating method. The present study showed that cross-plot comparisons of ostracode abundance and each environmental factor, based on sediment core data, could be used to identify ostracode species as indicators for anthropogenic influences. Ostracode abundance reflected mainly the changes that had occurred in total organic carbon content in sediments related to eutrophication, but heavy metal concentration did not directly influence several ostracode abundance in the bay. Environmental deterioration because of eutrophication started in the 1960s. The regulations regarding the chemical oxygen demand in waters introduced in the 1980s probably influence ostracode abundance for certain species in this period. Currently, Kasado Bay is not experiencing severe degradation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stereo photo series for quantifying natural fuels.Volume XIII: grasslands, shrublands, oak-bay woodlands, and eucalyptus forests in the East Bay of California.

Treesearch

Clinton S. Wright; Robert E. Vihnanek

2014-01-01

Four series of photographs display a range of natural conditions and fuel loadings for grassland, shrubland, oak-bay woodland, and eucalyptus forest ecosystems on the eastern slopes of the San Francisco Bay area of California. Each group of photos includes inventory information summarizing vegetation composition, structure, and loading; woody material loading and...

Assessment of Potential Impact of Electromagnetic Fields from Undersea Cable on Migratory Fish Behavior

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

Klimley, A. P.; Wyman, M. T.; Kavet, Rob

The US Department of Energy and US Department of the Interior, Bureau of Ocean Energy Management commissioned this study to address the limited scientific data on the impacts of high voltage direct current cables on aquatic biota, in particular migratory species within the San Francisco Bay. Empirical evidence exists that marine animals perceive and orient to local distortions in the earth’s main geomagnetic field magnetic field. The electromagnetic fields (EMF) generated by the cables that carry electricity from hydrokinetic energy sources to shore-based power stations may produce similar local distortions in the earth’s main field. Concern exists that animals thatmore » migrate along the continental shelves might orient to the EMF from the cables, and move either inshore or offshore away from their normal path. The Trans Bay Cable (TBC) is a ±200-kilovolt (kV), 400 MW 85-km long High Voltage Direct Current (DC) buried transmission line linking Pittsburg, CA with San Francisco, CA (SF) through the San Francisco Bay. The study addresses the following specific questions based on measurements and projections of the EMF produced by an existing marine cable, the TBC, in San Francisco Bay. Specifically, does the presence of EMF from an operating power cable alter the behavior and path of bony fishes and sharks along a migratory corridor? Does the EMF from an operating power cable guide migratory movements or pose an obstacle to movement? To meet the main study objectives several activities needed to be carried out: 1) modeling of the magnetic fields produced by the TBC, 2) assessing the migratory impacts on Chinook salmon smolts (Oncorhynchus tshawytscha) and green sturgeon (Acipenser medirostris) as a result of local magnetic field distortions produced by bridge structures and 3) analyzing behavioral responses by migratory Chinook salmon and green sturgeon to a high-voltage power cable. To meet the first objective, magnetic field measurements were made using two submerged Geometrics magnetometers towed behind a survey vessel in four locations in the San Francisco estuary along profiles crossing the cable path. We applied basic formulas to describe magnetic field from a DC cable summed vectorially with the background geomagnetic field (in the absence of other sources that would perturb the ambient field) to derive characteristics of the cable not immediately or otherwise observable. The magnetic field profiles of 76 survey lines were regressed against the measured fields, representing eight days of measurement. Many profiles were dominated by field distortions caused by bridge structures or other submerged objects, and the cable contribution to the field was not detectable. The regressions based on fundamental principles (Biot Savart law) and the vectorial summation of cable and geomagnetic fields provide estimates of cable characteristics consistent with plausible expectations. For the second objective, detailed gradiometer survey were examined. Distortions in the earth’s main field produced by bridges across the estuary were much greater than those from the TBC. The former anomalies exceeded the latter by an order of magnitude or more. Significant numbers of tagged Chinook salmon smolts migrated past bridges, which produced strong magnetic anomalies, to the Golden Gate Bridge, where they were recorded by dual arrays of acoustic tag-detecting monitors moored in lines across the mouth of the bay. Adult green sturgeon successfully swam upstream and downstream through the estuary on the way to and from their spawning grounds. Hence, the large anomalies produced by the bridges that run perpendicular to these migration routes do not appear to present a strong barrier to the natural seasonal movement patterns of salmonid smolts and adult green sturgeon. Finally, to assess the behavioral responses by migratory Chinook salmon and green sturgeon to a high- voltage power cable - the potential impacts effect of the TBC on fishes migrating through the San Francisco Estuary were examined. These included late-fall run Chinook salmon smolts (Oncorhynchus tshawytscha) that migrate downstream through the San Francisco Estuary to the Pacific Ocean and adult green sturgeon (Acipenser medirostris), which migrate upstream from the ocean through the estuary to their spawning habitat in the upper Sacramento River and return to the ocean after spawning occurs. Our results indicate Chinook salmon smolts may be attracted to the cable after activation (more cable location crossings, more detections at Bay Bridge, high importance of distance to cable in predicting fish location), but are not impeded from successfully migrating through the San Francisco Bay (similar proportions of successful exits, faster transit rates). Cable activity had opposite effects on outbound and inbound green sturgeon migrations: outbound migrations had significantly longer transit times while inbound migrations had significantly shorter migration times. However, the proportion of green sturgeon that successfully migrated through the San Francisco Bay was not strongly impacted after cable activation for either migration type. Based on the work, we provide the following conclusions: 1) calculations of magnetic fields for assessment of marine life can be performed; however, local anomalies in the fields resulting from submerged structures require validation of such calculations through collection of ambient DC magnetic field data, 2) the large anomalies produced by the bridges that run perpendicular to these migration routes do not appear to present a strong barrier to the natural seasonal movement patterns of salmonid smolts and adult green sturgeon and 3) Chinook salmon smolts may be attracted to the activated cable based on analysis of cable crossing, misdirections, and first presence at the array data, however, the cable activation does not appear to change the proportion of smolts that successfully migrate through the San Francisco Bay. Cable activation impacts inbound and outbound migrating adult green sturgeon: travel time was increased for outbound migrations but decreased for inbound migrations. However, cable activation did not appear to impact the success of either migration type in this species.« less

Melt in the impact breccias from the Eyreville drill cores, Chesapeake Bay impact structure, USA

NASA Astrophysics Data System (ADS)

Bartosova, Katerina; Hecht, Lutz; Koeberl, Christian; Libowitzky, Eugen; Reimold, Wolf Uwe

2011-03-01

The center of the 35.3 Ma Chesapeake Bay impact structure (85 km diameter) was drilled during 2005/2006 in an ICDP-0USGS drilling project. The Eyreville drill cores include polymict impact breccias and associated rocks (1397-01551 m depth). Tens of melt particles from these impactites were studied by optical and electron microscopy, electron microprobe, and microRaman spectroscopy, and classified into six groups: m1—clear or brownish melt, m2—brownish melt altered to phyllosilicates, m3—colorless silica melt, m4—melt with pyroxene and plagioclase crystallites, m5—dark brown melt, and m6—melt with globular texture. These melt types have partly overlapping major element abundances, and large compositional variations due to the presence of schlieren, poorly mixed melt phases, partly digested clasts, and variable crystallization and alteration. The different melt types also vary in their abundance with depth in the drill core. Based on the chemical data, mixing calculations were performed to determine possible precursors of these melt particles. The calculations suggest that most melt types formed mainly from the thick sedimentary section of the target sequence (mainly the Potomac Formation), but an additional crystalline basement (schist/gneiss) precursor is likely for the most abundant melt types m2 and m5. Sedimentary rocks with compositions similar to those of the melt particles are present among the Eyreville core samples. Therefore, sedimentary target rocks were the main precursor of the Eyreville melt particles. However, the composition of the melt particles is not only the result of the precursor composition but also the result of changes during melting and solidification, as well as postimpact alteration, which must also be considered. The variability of the melt particle compositions reflects the variety of target rocks and indicates that there was no uniform melt source. Original heterogeneities, resulting from melting of different target rocks, may be preserved in impactites of some large impact structures that formed in volatile-rich targets, because no large melt body exists, in which homogenization would have taken place.

Impact of huge tsunami in March 2011 on seaweed bed distributions in Shizugawa Bay, Sanriku Coast, revealed by remote sensing

NASA Astrophysics Data System (ADS)

Sakamoto, Shingo X.; Sasa, Shuji; Sawayama, Shuhei; Tsujimoto, Ryo; Terauchi, Genki; Yagi, Hiroshi; Komatsu, Teruhisa

2012-10-01

Seaweed beds are very important for abalones and sea urchins as a habitat. In Sanriku Coast, these animals are target species of coastal fisheries. The huge tsunami hit Sanriku Coast facing Pacific Ocean on 11 March 2011. It is needed for fishermen to know present situation of seaweed beds and understand damages of the huge tsunami on natural environments to recover coastal fisheries. We selected Shizugawa Bay as a study site because abalone catch of Shizugawa Bay occupied the first position in Sanriku Coast. To evaluate impact of tsunami on seaweed beds, we compared high spatial resolution satellite image of Shizugawa Bay before the tsunami with that after the tsunami by remote sensing with ground surveys to know impact of the tsunami on seaweed beds. We used two multi-band imageries of commercial high-resolution satellite, Geoeye-1, which were taken on 4 November 2009 before the tsunami and on 22 February 2012 after the tsunami. Although divers observed the tsunami damaged a very small part of Eisenia bicyclis distributions on rock substrates at the bay head, it was not observed clearly by satellite image analysis. On the other hand, we found increase in seaweed beds after the tsunami from the image analysis. The tsunami broke concrete breakwaters, entrained a large amount of rocks and pebble from land to the sea, and disseminated them in the bay. Thus, hard substrates suitable for attachment of seaweeds were increased. Ground surveys revealed that seaweeds consisting of E. bicyclis, Sargassum and Laminaria species grew on these hard substrates on the sandy bottom.

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part I hydrodynamics

NASA Astrophysics Data System (ADS)

Li, Li; Guan, Weibing; Hu, Jianyu; Cheng, Peng; Wang, Xiao Hua

2018-06-01

Xiangshan Bay consists of a deep tidal channel and three shallow inlets. A large-scale tidal flat has been utilized through coastal construction. To ascertain the accumulate influences of these engineering projects upon the tidal dynamics of the channel-inlets system, this study uses FVCOM to investigate the tides and flow asymmetries of the bay, and numerically simulate the long-term variations of tidal dynamics caused by the loss of tidal flats. It was found that the reduction of tidal flat areas from 1963 to 2010 slightly dampened M2 tidal amplitudes (0.1 m, ∼6%) and advanced its phases by reducing shoaling effects, while amplified M4 tidal amplitudes (0.09 m, ∼27%) and advanced its phases by reducing bottom friction, in the inner bay. Consequently, the ebb dominance was dampened indicated by reduced absolute value of elevation skewness (∼20%) in the bay. The tides and tidal asymmetry were impacted by the locations, areas and slopes of the tidal flats through changing tidal prism, shoaling effect and bottom friction, and consequently impacted tidal duration asymmetry in the bay. Tides and tidal asymmetry were more sensitive to the tidal flat at the head of the bay than the side bank. Reduced/increased tidal flat slopes around the Tie inlet dampened the ebb dominance. Tidal flat had a role in dissipating the M4 tide rather than generating it, while the advection only play a secondary role in generating the M4 tide. The full-length tidal flats reclamation would trigger the reverse of ebb to flood dominance in the bay. This study would be applicable for similar narrow bays worldwide.

Correlating Distal, Medial and Proximal Ejecta Transport/Emplacement From Oblique Cosmic Impact On North American Continental Ice Sheet At MIS20 ( 786 ka) Via Suborbital Analysis (SA).

NASA Astrophysics Data System (ADS)

Harris, T. H. S.; Davais, M. E.

2017-12-01

Several elements of the 786 ka Australasian (AA) tektite imprint bear close scrutinyin order to locate the parent impact site or structure. The unique Carolina bays unit geologic formation is indicated as a large "medial" ejecta blanket from a large cosmic impact during a period containing 786 ka. Coincidence? Kg-scale sub-spherical hollow splash form AA tektites implies prolonged atmospheric blow out-scale momentum current with a core of sub-parallel or divergent flow volume having essentially zero turbulence. This would allow for plasma entrainment and heating of target mass at prolonged low dynamic pressure during outflow, where adiabatic expansion could deliver both semi-solid Muong Nong-type and inviscid melts above the atmosphere for gentle release upon rarefaction in vacuum. Within a large atmospheric blow-out scale momentum current, target mass becomes entrained at the speed of adiabatic outflow. 10+ km/s ejecta entrainment yields inter-hemispheric emplacement from launch per governing suborbital mechanics, without question. Oblique impact into a thick ice sheet explains reduced excavation volume and shearing disruption in the form of hypersonic steam plasma scouring. Adiabatic expansion would be immediately available to accelerate and further heat proto-tektite target mass. With shock no longer the sole transport engine, kg-scale splash forms and tektite speeds above the post-shock vaporization velocity of quartz are explained by expansion of shocked ice, in agreement with the observed imprint. The 6 Carolina bay shapes or "Davias Archetypes" are reproducible using conic perturbation in Suborbital Analysis, conforming to a formative mechanism of suborbital transport and ballistic emplacement: "Suborbital Obstruction Shadowing" needs only 3 parts in 10,000 of VEL variation around a circular EL-AZ-VEL launch cone, before considering re-entry effects. Transport energy of the Carolina bay sand, calculated using the 3.5 to 4 km/s launch VEL required for its indicated transport, must account for inefficiency of entrained transport. Roughly 1600 cubic kilometers of Carolina bays sand must have taken 10 to 1000 times more energy to transport than the entire Chixulub event yield. Imagery by M. E. Davias of Cintos.org, S.E. Nebraska (top) and Bennettsville, South Carolina (bottom).

Brief communication: Impacts of a developing polynya off Commonwealth Bay, East Antarctica, triggered by grounding of iceberg B09B

NASA Astrophysics Data System (ADS)

Fogwill, Christopher J.; van Sebille, Erik; Cougnon, Eva A.; Turney, Chris S. M.; Rintoul, Steve R.; Galton-Fenzi, Benjamin K.; Clark, Graeme F.; Marzinelli, E. M.; Rainsley, Eleanor B.; Carter, Lionel

2016-11-01

The dramatic calving of the Mertz Glacier tongue in 2010, precipitated by the movement of iceberg B09B, reshaped the oceanographic regime across the Mertz Polynya and Commonwealth Bay, regions where high-salinity shelf water (HSSW) - the precursor to Antarctic bottom water (AABW) - is formed. Here we present post-calving observations that suggest that this reconfiguration and subsequent grounding of B09B have driven the development of a new polynya and associated HSSW production off Commonwealth Bay. Supported by satellite observations and modelling, our findings demonstrate how local icescape changes may impact the formation of HSSW, with potential implications for large-scale ocean circulation.

36 CFR 910.69 - Structural bay.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Structural bay. 910.69 Section 910.69 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION GENERAL GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE...

36 CFR 910.69 - Structural bay.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Structural bay. 910.69 Section 910.69 Parks, Forests, and Public Property PENNSYLVANIA AVENUE DEVELOPMENT CORPORATION GENERAL GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE...

Gulf of Mexico Integrated Science - Tampa Bay Study: Examining the Impact of Urbanization on Seafloor Habitats

USGS Publications Warehouse

Yates, Kimberly

2005-01-01

Seafloor habitats, such as seagrass beds, provide essential habitat for fish and marine mammals. For many years, the study of seagrass vitality has been a priority for scientists and resource managers working in Tampa Bay. Seafloor habitats are extremely sensitive to changes in water quality. Like a canary in a coal mine, seagrass can serve as an ecological indicator of estuary health. Between the 1940s and the 1970s, seagrass gradually died in Tampa Bay. This loss has been attributed to a rise in urbanization and an increase in nutrient loading into the bay. Better treatment of industrial wastewater and runoff beginning in the 1980s resulted in the continuous recovery of seagrass beds. However, in the mid-1990s, the recovery began to level off in areas where good water quality was expected to support continued seagrass recovery, demonstrating that nutrient loading may be only one factor impacting seagrass health. Researchers now are trying to determine what might be affecting the recovery of seagrass in these areas. Currently, little is understood about the effects that other aspects of urbanization and natural change, such as groundwater and sediment quality, might have on seagrass vitality. This segment of the Tampa Bay integrated science study is intended to identify, quantify, and develop models that illustrate the impact that urbanization may have on seafloor habitat distribution, health, and restoration.

Beach boundary layer: a framework for addressing recreational water quality impairment at enclosed beaches.

PubMed

Grant, Stanley B; Sanders, Brett F

2010-12-01

Nearshore waters in bays, harbors, and estuaries are frequently contaminated with human pathogens and fecal indicator bacteria. Tracking down and mitigating this contamination is complicated by the many point and nonpoint sources of fecal pollution that can degrade water quality along the shore. From a survey of the published literature, we propose a conceptual and mathematical framework, the "beach boundary layer model", for understanding and quantifying the relative impact of beach-side and bay-side sources of fecal pollution on nearshore water quality. In the model, bacterial concentration in ankle depth water C(ankle) [bacteria L(-3)] depends on the flux m'' [bacteria L(-2) T(-1)] of fecal bacteria from beach-side sources (bather shedding, bird and dog feces, tidal washing of sediments, decaying vegetation, runoff from small drains, and shallow groundwater discharge), a cross-shore mass transfer velocity k [L T(-1)] that accounts for the physics of nearshore transport and mixing, and a background concentration C(bay) [bacteria L(-3)] attributable to bay-side sources of pollution that impact water quality over large regions (sewage outfalls, creeks and rivers): C(ankle) = m''/k + C(bay). We demonstrate the utility of the model for identifying risk factors and pollution sources likely to impact shoreline water quality, and evaluate the model's underlying assumptions using computational fluid dynamic simulations of flow, turbulence, and mass transport in a trapezoidal channel.

An Assessment of Potential Mining Impacts on Salmon ...

EPA Pesticide Factsheets

The Bristol Bay watershed in southwestern Alaska supports the largest sockeye salmon fishery in the world, is home to 25 federally recognized tribal governments, and contains large mineral resources. The potential for large-scale mining activities in the watershed has raised concerns about the impact of mining on the sustainability of Bristol Bay’s world-class commercial, recreational and subsistence fisheries and the future of Alaska Native tribes in the watershed who have maintained a salmon-based culture and subsistence-based way of life for at least 4,000 years. The purpose of this assessment is to provide a characterization of the biological and mineral resources of the Bristol Bay watershed, increase understanding of the potential impacts of large-scale mining on the region’s fish resources, and inform future government decisions related to protecting and maintaining the chemical, physical, and biological integrity of the watershed. It will also serve as a technical resource for the public, tribes, and governments who must consider how best to address the challenges of mining and ecological protection in the Bristol Bay watershed. The purpose of this assessment is to understand how future large-scale mining may affect water quality and the Bristol Bay salmon fisheries, which includes the largest wild sockeye salmon fishery in the world. Bristol Bay, Alaska, is home to a salmon fishery that is of significant economic and subsistence value to the peopl

Sediment transport in the San Francisco Bay Coastal System: An overview

USGS Publications Warehouse

Barnard, Patrick L.; Schoellhamer, David H.; Jaffe, Bruce E.; Lester J. McKee,

2013-01-01

The papers in this special issue feature state-of-the-art approaches to understanding the physical processes related to sediment transport and geomorphology of complex coastal-estuarine systems. Here we focus on the San Francisco Bay Coastal System, extending from the lower San Joaquin-Sacramento Delta, through the Bay, and along the adjacent outer Pacific Coast. San Francisco Bay is an urbanized estuary that is impacted by numerous anthropogenic activities common to many large estuaries, including a mining legacy, channel dredging, aggregate mining, reservoirs, freshwater diversion, watershed modifications, urban run-off, ship traffic, exotic species introductions, land reclamation, and wetland restoration. The Golden Gate strait is the sole inlet connecting the Bay to the Pacific Ocean, and serves as the conduit for a tidal flow of ~ 8 x 109 m3/day, in addition to the transport of mud, sand, biogenic material, nutrients, and pollutants. Despite this physical, biological and chemical connection, resource management and prior research have often treated the Delta, Bay and adjacent ocean as separate entities, compartmentalized by artificial geographic or political boundaries. The body of work herein presents a comprehensive analysis of system-wide behavior, extending a rich heritage of sediment transport research that dates back to the groundbreaking hydraulic mining-impact research of G.K. Gilbert in the early 20th century.

Managed nutrient reduction impacts on nutrient concentrations, water clarity, primary production, and hypoxia in a north temperate estuary

NASA Astrophysics Data System (ADS)

Oviatt, Candace; Smith, Leslie; Krumholz, Jason; Coupland, Catherine; Stoffel, Heather; Keller, Aimee; McManus, M. Conor; Reed, Laura

2017-12-01

Except for the Providence River and side embayments like Greenwich Bay, Narragansett Bay can no longer be considered eutrophic. In summer 2012 managed nitrogen treatment in Narragansett Bay achieved a goal of reducing effluent dissolved inorganic nitrogen inputs by over 50%. Narragansett Bay represents a small northeast US estuary that had been heavily loaded with sewage effluent nutrients since the late 1800s. The input reduction was reflected in standing stock nutrients resulting in a statistically significant 60% reduction in concentration. In the Providence River estuary, total nitrogen decreased from 100 μm to about 40 μm, for example. We tested four environmental changes that might be associated with the nitrogen reduction. System apparent production was significantly decreased by 31% and 45% in the upper and mid Bay. Nutrient reductions resulted in statistically improved water clarity in the mid and upper Bay and in a 34% reduction in summer hypoxia. Nitrogen reduction also reduced the winter spring diatom bloom; winter chlorophyll levels after nutrient reduction have been significantly lower than before the reduction. The impact on the Bay will continue to evolve over the next few years and be a natural experiment for other temperate estuaries that will be experiencing nitrogen reduction. To provide perspective we review factors effecting hypoxia in other estuaries with managed nutrient reduction and conclude that, as in Narragansett Bay, physical factors can be as important as nutrients. On a positive note managed nutrient reduction has mitigated further deterioration in most estuaries.

Revisiting the West Clearwater Lake Impact Structure, Canada

NASA Technical Reports Server (NTRS)

Osinski, G. R.; Brunner, A.; Collins, G.; Cohen, B. A.; Coulter, A.; Elphic, R.; Grieve, R. A. F.; Hodges, K.; Horne, A.; Kerrigan, M.

2015-01-01

The West and East Clearwater Lake impact structures are two of the most distinctive and recognizable impact structures on Earth. Known regionally as the "Clearwater Lake Complex", these structures are located in northern Quebec, Canada (56 deg 10 N, 74 deg 20 W) approximately 125 km east of Hudson Bay. The currently accepted diameters are 36 km and 26 km for the West and East structures, respectively. Long thought to represent a rare example of a double impact, recent age dating has called this into question with ages of approximately 286 Ma and approximately 460-470 Ma being proposed for the West and East structures, respectively. Relatively little is known about the East Clearwater Lake structure. There is no surface exposure and what information there is comes from geophysics and two drill cores obtained in the 1960s. In contrast, the West Clearwater Lake structure is relatively well preserved with large ring of islands in the approximately 30 km diameter lake. Much of the work done on West Clearwater stems from field investigations carried out in 1977 driven by the Apollo program, with a focus on the impact melt rocks and other impactites, which are well exposed on the ring of islands. To our knowledge, the Clearwater Lake impact structures have not been the focus of detailed impact geology field investigations since the 1977 expedition and the only geological map that exists is from the 1960s and is at the reconnaissance level. Our knowledge of impact cratering processes have increased substantially since this time, as have the analytical techniques available for samples. This provided the motivation for a joint Canadian-US-UK expedition to the West Clearwater Lake impact structure in August and September 2015, under the auspices of the FINESSE (Field Investigations to Enable Solar System Science and Exploration) project, part of NASA's Solar System Exploration Research Virtual Institute (SSERVI). We focus here on the impactites of the West Clearwater Lake impact structure. Other ongoing studies, also presented at this conference, focus on central uplift formation, the impact-generated hydrothermal system, xxxx and using WCIS as an analog test site for crew studies of sampling protocols].

Mixed Layer Heat and Fresh Water Balance in North Bay of Bengal (18N, 90E) Using a Seaglider and Mooring

NASA Astrophysics Data System (ADS)

Thangaprakash, V. P.; Girishkumar, M. S.; S, S.; Chaudhuri, D.; Sureshkumar, N.; Ravichandran, M.; Sengupta, D.; Weller, R. A.

2016-02-01

The Bay of Bengal (BoB) receives the large quantity of freshwater by excess precipitation over evaporation and runoff. This large freshwater flux into the BoB leads to strong haline stratification in the near surface layer, which have significant impact on the evolution of near thermo-haline structure and air-sea interactions process in those areas. However, lack of systematic measurements of observations, the factors that are modulating near mixed layer salinity and temperature in these freshwater pool in the northern BoB is not yet understood clearly. Under OMM - ASIRI (Ocean mixing and monsoon - Air sea interaction regional initiatives in the Northern Indian Ocean) programme, 3 month repeated hydrographic survey using seaglider in a butterfly (or bowtie) track centered around a mooring in the North Bay of Bengal (18N, 89E) equipped with near surface ASIMET sensors and subsurface temperature and salinity measurements, which provides unprecedental data source to quantify the relative contribution of different process on the evolution of near surface thermo-haline field through mixed layer heat and salt budget. The results of the analysis will be presented.

Sediment quality triad assessment survey of the Galveston Bay, Texas system

USGS Publications Warehouse

Carr, R. Scott; Chapman, Duane C.; Howard, Cynthia L.; Biedenbach, James M.

1996-01-01

To characterize the quality of sediments at key sites in the Galveston Bay Estuary, sediment samples were collected concurrently for chemical and physical analyses, toxicity testing and an assessment of benthic community structure. Significant toxicity, as determined by the sea urchin (Arbacia punetulata) pore water embryological development assay, was observed at 12 of the 24 sites investigated in this study. No toxicity was observed at any of the sites with the amphipod (Grandidierella japonica) solid-phase test. There were a number of sites with elevated levels of trace metals and petroleum hydrocarbons. The chemistry, toxicity and benthic data were ranked by station and a scaled rank sum was calculated to facilitate comparisons among the stations. Five sites exhibited strong evidence of contaminant-induced degradation, while 15 stations showed no evidence of contaminant-induced degradation. At eight additional sites the sediment quality triad (SQT) data indicated that unmeasured chemicals or conditions were stressing the system. Contaminant impacts could be reduced or eliminated by alternative regulatory and management practices, including the restriction of produced water discharges into coastal estuaries and the use of dredge material disposal practices that minimize the reintroduction of sediment-associated contaminants to the bays.

Macrofaunal Succession and Community Structure in Salicornia Marshes of Southern California

NASA Astrophysics Data System (ADS)

Talley, T. S.; Levin, L. A.

1999-11-01

Lack of basic understanding of ecosystem structure and function forms a major impediment to successful conservation of coastal ecosystems. This paper provides a description of the fauna and examines faunal succession in Salicornia -vegetated sediments of southern California. Environmental attributes (vegetation and sediment properties) and macrofaunal (animals ≥0·3 mm) community structure were examined in sediments of five natural, southern California Salicornia spp. marshes (Tijuana Estuary, San Diego Bay, Mission Bay, Upper Newport Bay and Anaheim Bay) and in created Salicornia marshes 16 months to 10 years in age, located within four of the bays. Oligochaetes and insects were the dominant taxa in both natural (71 to 98% of total fauna) and created (91 to 97%) marshes. In San Diego, Newport and Anaheim Bays, macrofaunal densities were generally higher in the created marshes (88 000 to 290 000 ind m -2) than in their natural counterparts (26 000 to 50 000 ind m -2). In the youngest system, Mission Bay, the reverse was true (natural: 113 000 vs created: 28 000 ind m -2). Similar species numbers were recorded from the created and adjacent natural marshes. Insects, especially chironomids, dolichopodids, and heleids, as well as the naidid oligochaete, Paranais litoralis, characterize early successional stages. Enchytraeid and tubificid oligochaetes reflect later succession evident in natural and older created marshes. Sediment organic matter (both combustible and below-ground plant biomass) was the environmental variable most commonly associated with densities of various macrofaunal taxa. These relationships were generally negative in the natural marshes and positive in the created marshes. Within-bay comparisons of macrofauna from natural Salicornia- vs Spartina -vegetated habitat in San Diego and Mission Bays revealed lower macrofaunal density (San Diego Bay only), proportionally fewer oligochaetes and more insects, and no differences in species richness in the Salicornia habitat. The oldest created Salicornia marsh (San Diego Bay) exhibited an assemblage intermediate in composition between those of the natural Salicornia- and Spartina- vegetated marshes. These results suggest: (a) faunal recovery following Salicornia marsh creation can require 10 or more years, (b) high macrofaunal variability among bays requires marsh creation reference site selection from within the same bay, and (c) Spartina -based research should not be used for Salicornia marsh management decisions.

ASSESSING THE IMPACTS OF SALINITY AND NUTRIENT ...

EPA Pesticide Factsheets

Healthy seagrass beds were once found throughout the shallow areas of Narragansett Bay, R.I. but have disappeared due to infilling, pollution and disease. In Greenwich Bay, a highly developed embayment within Narragansett Bay, Ruppia maritima has colonized an area on the northern shore once dominated by Zostera marina. This area is sandy, which may allow groundwater seepage. Ruppia is extremely salinity tolerant, and may also be more nutrient tolerant than Zostera. A six week microcosm experiment at two salinity (20 and 30 ppt) and 4 nutrient (0, 5, 10, and 30 µM inorganic N) levels to test their relative tolerance was conducted in 2014. Treatments were renewed daily to simulate tidal flushing and the exposure water was dosed with 15N for the first week of the experiment. At the end of the experiment, the plants were weighed and measured, and dried for later isotopic analysis. In the first experiment, Ruppia had significant structural responses to both nutrients and salinity; there was a slight decline in root weight and a decrease in the total number of shoots with increasing nutrients. Average Ruppia blade length decreased with increasing nutrients and this decrease was more evident at 30 ppt. In contrast, Zostera had no significant structural differences. For both species, there were no differences in shoot or root/rhizome weights in any treatment, nor were there differences in isotopic results due to salinity. However, δ15N in the tissue increase

BENTHIC MACROFAUNA AND HABITAT RELATIONSHIPS IN TILLAMOOK BAY

EPA Science Inventory

Tillamook Bay is subject to natural and man-made stressors, such as increased nutrients and sediments, which can alter its habitats and, thereby, impact its productivity and ecological resources. The benthic macrofauna are small, sediment-dwelling invertebrates which have strong...

The impact of water quality in Narragansett Bay on housing prices

NASA Astrophysics Data System (ADS)

Liu, Tingting; Opaluch, James J.; Uchida, Emi

2017-08-01

We examine the impact of water quality in Narragansett Bay on housing prices in coastal towns and cities using a hedonic housing-price model. Unlike other hedonic studies of water quality, we test whether housing market responds to average water quality or more to extreme events. We also test the spatial and temporal extent of effects of water quality on housing prices. We find that poor coastal water quality, measured in terms of the concentration of chlorophyll, has a negative impact on housing prices that diminishes with distance from the shoreline. Furthermore, our finding suggests that housing prices are most influenced by the extreme environmental conditions, which may be accompanied by unpleasant odors, discoloration, and even fish kills. We further predict potential increases in home values associated under water quality improvement scenarios and find an increase in the values of homes in coastal communities along Narragansett Bay of about 18 million up to 136 million.

Impact of Off-road Vehicles (ORVs) on Ghost Crabs of Sandy Beaches with Traffic Restrictions: A Case Study of Sodwana Bay, South Africa

NASA Astrophysics Data System (ADS)

Lucrezi, Serena; Saayman, Melville; van der Merwe, Peet

2014-03-01

Off-road vehicles (ORVs) are popular in coastal recreation, although they have negative impacts on sandy shores. In South Africa, ORVs are banned from most coastal areas, while some areas are designated for restricted ORV use, providing an opportunity to assess whether ORV traffic restrictions translate into biological returns. In Sodwana Bay, the impact of ORVs on ghost crab populations was investigated. During Easter 2012, ghost crab burrows were counted on beach sections open and closed to traffic. Burrow density in the Impact section was less than a third that of the Reference section, and by the end of the study burrow size in the Impact section was half that of the Reference section. ORV traffic caused a shift in burrow distribution to the Lower beach. However, differences in burrow densities between sections were 14 times smaller than differences obtained at a time when ORV use in Sodwana Bay was not controlled. While confirming the well-established detrimental effects of ORV use on sandy beach ecosystems, results demonstrated that traffic restrictions on beaches measurably minimize impacts to the fauna, thus translating into clear-cut biological returns.

Bahía de Banderas, Mexico: Morphology, Magnetic Anomalies and Shallow Structure

NASA Astrophysics Data System (ADS)

Mortera Gutiérrez, Carlos A.; Bandy, William L.; Ponce Núñez, Francisco; Pérez Calderón, Daniel A.

2016-10-01

The Bahía de Banderas lies within a tectonically complex area at the northern end of the Middle America Trench. The structure, morphology, subsurface geology and tectonic history of the bay are essential for unraveling the complex tectonic processes occurring in this area. With this focus, marine geophysical data (multi-beam bathymetry, high resolution seismic reflection and total field magnetic data) were collected within the bay and adjacent areas during four campaigns aboard the B.O. EL PUMA conducted in 2006 and 2009. These data image the detailed morphology of, and sedimentation patterns within, the Banderas Canyon (a prominent submarine canyon situated on the south side of the bay) as well as the shallow subsurface structure of the northern part of the bay and the submarine Marietas Ridge, which bounds the bay to the west. We find that the Marietas Ridge is presently a transtensional feature; the course of the Banderas Canyon is controlled by extensive turbidite fan sedimentation in its eastern extremity and by structural lineaments to the west; the canyon floor is filled by sediments and exhibits almost no evidence for recent tectonic movements; the southern canyon wall is quite steep and a few sediments are deposited as submarine fans at the base of the southern wall; and extensive turbidite fans form the lower part of the northern canyon wall, producing a gently sloping lower northern wall. We find no evidence for a regional east-west striking lineament between the bay and the Middle America Trench, which casts doubts on the previous assertion that the Banderas Canyon is unequivocally related to the presence of a regional half-graben. Finally, a N71°E oriented normal fault offsets the seafloor reflector by 15 m within the central part of the bay, suggesting that the bay is currently being subjected to NNW-SSE extension.

Description of gravity cores from San Pablo Bay and Carquinez Strait, San Francisco Bay, California

USGS Publications Warehouse

Woodrow, Donald L.; John L. Chin,; Wong, Florence L.; Fregoso, Theresa A.; Jaffe, Bruce E.

2017-06-27

Seventy-two gravity cores were collected by the U.S. Geological Survey in 1990, 1991, and 2000 from San Pablo Bay and Carquinez Strait, California. The gravity cores collected within San Pablo Bay contain bioturbated laminated silts and sandy clays, whole and broken bivalve shells (mostly mussels), fossil tube structures, and fine-grained plant or wood fragments. Gravity cores from the channel wall of Carquinez Strait east of San Pablo Bay consist of sand and clay layers, whole and broken bivalve shells (less than in San Pablo Bay), trace fossil tubes, and minute fragments of plant material.

Built-up Al-Li structures for cryogenic tank and dry bay applications

NASA Technical Reports Server (NTRS)

Lisagor, W. Barry

1993-01-01

The objectives are: (1) to demonstrate the cost benefits of built-up cryotank and dry bay structures; (2) to study of benefits of using Al alloys; (3) to study of benefit of using Al-Li alloys; (4) to evaluate alternative low-cost stiffener and joining concepts.

Chesapeake Bay Low Freshwater Inflow Study. Biota Assessment. Phase I. Volume I.

DTIC Science & Technology

1980-08-01

Percentage as Larvae Containing Food Item . . . 70 111-9. Submerged Aquatic Vegetation Found in Maryland and Virginia Waters of the Chesapeake Bay ... .... 74...Composition or the 1977 and 1978 Water - fowl Hunting Kill for Maryland and Virginia. . . . 117 IV-1. Annual Mean Freshwater Inflow to Chesapeake Bay...15C IV-3. Sumary of Water Quality Factors Impacting the Low Freshwater Inflow on Biota .. ............. 163 IV-4. Ranked Relative Importance of

Fresh Water Inflow and Oyster Productivity in Apalachicola Bay, FL (USA)

EPA Science Inventory

Apalachicola Bay lies at the mouth of the Apalachicola River, where seasonally variable freshwater inflows and shifting winds support an unusually productive and commercially important oyster fishery. While there is concern that upstream water withdrawals may impact the fishery,...

A Creek to Bay Biological Assessment in Oakland, California

NASA Astrophysics Data System (ADS)

Ahumada, E.; Ramirez, N.; Lopez, A.; Avila, M.; Ramirez, J.; Arroyo, D.; Bracho, H.; Casanova, A.; Pierson, E.

2011-12-01

In 2007, the Surface Water Ambient Monitoring Program (SWAMP) assessed the impact of trash on water quality in the Peralta Creek which is located in the Fruitvale district of Oakland, CA. This 2011 follow-up study will take further steps in evaluating the physical and biological impacts of pollution and human development on Peralta Creek and in the San Leandro Bay, where the Creek empties into the larger San Francisco Bay estuary. This study will utilize two forms of biological assessment in order to determine the level of water quality and ecosystem health of Peralta Creek and San Leandro Bay in Oakland, California. A Rapid Bioassesment Protocal (RBP) will be used as the method of biological assessment for Peralta Creek. RBP uses a biotic index of benthic macroinvertebrates to provide a measure of a water body's health. Larval trematodes found in two mud snails (Ilynassa obsoleta and Cerithidea californica) will be used to evaluate the health of the San Leandro Bay. Due to the complex life cycle of trematodes, the measure of trematode diversity and richness in host species serves as an indicator of estuarine health (Huspeni 2005). We have completed the assessment of one section of Peralta Creek, located at 2465 34th Avenue, Oakland, CA 94601. Abundance results indicate a moderately healthy creek because there were high levels of pollution tolerant benthic macroinvertebrates. The tolerant group of benthic macroinvertebrates includes such organisms as flatworms, leeches, and scuds. This is possibly due to this section of the creek being pumped up to the surface from culverts impacting the macroinvertebrate's life cycle. Another contributing factor to creek health is the amount of organic debris found in the creek, which inhibits the flow and oxygenation of the water, allowing for more pollution tolerant aquatic insects to persist. Further investigation is being conducted to fully assess the Peralta Creek watershed; from the preliminary results one can surmise that runoff from the watershed that leads into the bay may reflect a moderately healthy San Leandro Bay.

Mapping Oyster Reef Habitats in Mobile Bay

NASA Technical Reports Server (NTRS)

Bolte, Danielle

2011-01-01

Oyster reefs around the world are declining rapidly, and although they haven t received as much attention as coral reefs, they are just as important to their local ecosystems and economies. Oyster reefs provide habitats for many species of fish, invertebrates, and crustaceans, as well as the next generations of oysters. Oysters are also harvested from many of these reefs and are an important segment of many local economies, including that of Mobile Bay, where oysters rank in the top five commercial marine species both by landed weight and by dollar value. Although the remaining Mobile Bay oyster reefs are some of the least degraded in the world, projected climate change could have dramatic effects on the health of these important ecosystems. The viability of oyster reefs depends on water depth and temperature, appropriate pH and salinity levels, and the amount of dissolved oxygen in the water. Projected increases in sea level, changes in precipitation and runoff patterns, and changes in pH resulting from increases in the amount of carbon dioxide dissolved in the oceans could all affect the viability of oyster reefs in the future. Human activities such as dredging and unsustainable harvesting practices are also adversely impacting the oyster reefs. Fortunately, several projects are already under way to help rebuild or support existing or previously existing oyster reefs. The success of these projects will depend on the local effects of climate change on the current and potential habitats and man s ability to recognize and halt unsustainable harvesting practices. As the extent and health of the reefs changes, it will have impacts on the Mobile Bay ecosystem and economy, changing the resources available to the people who live there and to the rest of the country, since Mobile Bay is an important national source of seafood. This project identified potential climate change impacts on the oyster reefs of Mobile Bay, including the possible addition of newly viable habitats in the southeastern regions of the Bay.

Geophysical evidence for the extent of crustal types and the type of margin along a profile in the northeastern Baffin Bay

NASA Astrophysics Data System (ADS)

Altenbernd, Tabea; Jokat, Wilfried; Heyde, Ingo; Damm, Volkmar

2015-11-01

Investigating the crust of northern Baffin Bay provides valuable indications for the still debated evolution of this area. The crust of the southern Melville Bay is examined based on wide-angle seismic and gravity data. The resulting P wave velocity, density, and geological models give insights into the crustal structure. A stretched and rifted continental crust underneath southern Melville Bay is up to 30 km thick, with crustal velocities ranging between 5.5 and 6.9 km/s. The deep Melville Bay Graben contains a 9 km thick infill with velocities of 4 to 5.2 km/s in its lowermost part. West of the Melville Bay Ridge, a ~80 km wide and partly only 5 km thick Continent-Ocean Transition (COT) is present. West of the COT, up to 5 km thick sedimentary layers cover a 4.3 to 7 km thick, two-layered oceanic crust. The upper oceanic layer 2 has velocities of 5.2 to 6.0 km/s; the oceanic layer 3 has been modeled with rather low velocities of 6.3 to 6.9 km/s. Low velocities of 7.8 km/s characterize the probably serpentinized upper mantle underneath the thin crust. The serpentinized upper mantle and low thickness of the oceanic crust are another indication for slow or ultraslow spreading during the formation of the oceanic part of the Baffin Bay. By comparing our results on the crustal structure with other wide-angle seismic profiles recently published, differences in the geometry and structure of the crust and the overlying sedimentary cover are revealed. Moreover, the type of margin and the extent of crustal types in the Melville Bay area are discussed.

Eutrophication and carbon sources in Chesapeake Bay over the last 2700 yr: Human impacts in context

USGS Publications Warehouse

Bratton, J.F.; Colman, Steven M.; Seal, R.R.

2003-01-01

To compare natural variability and trends in a developed estuary with human-influenced patterns, stable isotope ratios (δ13C and δ15N) were measured in sediments from five piston cores collected in Chesapeake Bay. Mixing of terrestrial and algal carbon sources primarily controls patterns of δ13Corg profiles, so this proxy shows changes in estuary productivity and in delivery of terrestrial carbon to the bay. Analyses of δ15N show periods when oxygen depletion allowed intense denitrification and nutrient recycling to develop in the seasonally stratified water column, in addition to recycling taking place in surficial sediments. These conditions produced 15N-enriched (heavy) nitrogen in algal biomass, and ultimately in sediment. A pronounced increasing trend in δ15N of +4‰ started in about A.D. 1750 to 1800 at all core sites, indicating greater eutrophication in the bay and summer oxygen depletion since that time. The timing of the change correlates with the advent of widespread land clearing and tillage in the watershed, and associated increases in erosion and sedimentation. Isotope data show that the region has experienced up to 13 wet-dry cycles in the last 2700 yr. Relative sea-level rise and basin infilling have produced a net freshening trend overprinted with cyclic climatic variability. Isotope data also constrain the relative position of the spring productivity maximum in Chesapeake Bay and distinguish local anomalies from sustained changes impacting large regions of the bay. This approach to reconstructing environmental history should be generally applicable to studies of other estuaries and coastal embayments impacted by watershed development.

Historical sediment budget and present-day catchment-shoreline coupling at Twofold Bay, southeastern Australia

NASA Astrophysics Data System (ADS)

Tamura, T.; Oliver, T.; Hudson, J.; Woodroffe, C. D.

2017-12-01

Considering projected impacts of sea-level rise in the 21st century on sandy shorelines, an understanding of long-term sediment budget for individual beaches or coastal compartments supports assessments of shoreline stability. We examined a low-lying coastal beach-ridge barrier in Twofold Bay using optically stimulated luminescence (OSL) dating , airborne LiDAR, sedimentological analysis and seismic data to assess changes in rates of sediment supply to this shoreline through time. Calculations of barrier volume, Twofold Bay bay-floor sediment volume and estimates of sediment delivery from a proximal river system provide a broad-scale assessment of past-sediment budget. Between ca. 7500 years ago and 1500 years ago, sources of sediment for shoreline progradation at Boydtown were bay-floor sediments either inherited or moved into the embayment during late-stage transgression. Progradation rate between ca. 7500-1500 years ago was 0.16 m/yr with subaerial barrier volume accumulating at 0.46 m3/m/yr. Between ca. 1500 years and present day, the Towamba River to the south has delivered additional sediment to the Boydtown shoreline more than doubling shoreline progradation rate to 0.65 m/yr and subaerial barrier accumulation has risen to 1.83 m3/m/yr. The delivery of fluvial sediment from the Towamba River was restricted to the past ca. 1500 years as prior to this, estuary infilling prevented floods delivering sediments to the bay. This recent historical coupling of river sand supply and shoreline progradation rate implies that anthropogenic modifications to the Towamba River catchment such as river damming, or climatic changes reducing rainfall or runoff, would negatively impact the Boydtown Beach shoreline. Conversely increased rainfall or deforestation may increase sediment discharge due to upstream erosion. The Boydtown shoreline within Twofold Bay may be able to maintain its current position in the coming century if fluvial sediment delivery continues. The fact that other shorelines within Twofold Bay are seemingly unaffected by the Towamba River, and most shorelines in southeast Australia receive minimal fluvial sediment input, further emphasises the need to consider nearshore sediment reserves in order to accurately determine sea-level rise impacts on sandy shorelines.

GoMRC Website ‘Meta-analysis Report: Land-use and submerged aquatic vegetation change in the Gulf of Mexico’

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

Judd, Chaeli; Stefansson, Emily S.; Brushnahan, Heather

2007-12-06

Over the past century, health and spatial extent of seagrasses has decreased dramatically in the Gulf of Mexico. While some of the changes can be explained by direct impacts to the seagrass beds, we hypothesize that changes in the land use in the watersheds can also be correlated with the decline of seagrasses. Through this meta-analysis, we researched historical and compared trends in seagrass populations and land use in five bays and their watersheds within the Gulf of Mexico: Mobile Bay, Perdido Bay, Tampa Bay, Charlotte Harbor, and Galveston Bay. Using both historical records and spatial datasets, we examined landmore » use and seagrass trends in these five areas.« less

Drift of surface and near-bottom waters of the San Francisco Bay system, California March 1970 through April 1971

USGS Publications Warehouse

Conomos, T.J.; McCulloch, D.S.; Peterson, D.H.; Carlson, P.R.

1972-01-01

The San Francisco Bay system is a complex estuary in which there is an interplay between natural chemical and physical processes, and changes resulting from the works of man. The bay is used for recreation, water-borne commerce, fishing, domestic and industrial waste disposal, and esthetic pleasure. Because some of these uses are competitive, it is desirable to adequately predict the impact of man's activities on this natural system. The reliability of such predictions will be strengthened by long-term observations directed toward understanding the natural processes occurring in the bay. This study is a compilation of one aspect of the U.S. Geological Survey's continuing investigations of the San Francisco Bay system.

Analysis of Level of Technogenic Impact on Water Area of Uglovoy Bay

NASA Astrophysics Data System (ADS)

Petukhov, V. I.; Petrova, E. A.; Losev, O. V.

2017-11-01

Industrial effluent discharge and man-induced soil fills play a decisive role in increased pollutant concentrations. Several areas which are unfavorable in terms of the heavy metal and oil product content have been identified by the environmental monitoring results in the Uglovoy Bay in February 2015. Maximum permissible concentrations (MPC) of heavy metals and oil products were exceeded in the northeastern part of the Uglovoy Bay in locations where the Peschanka River and the Aerodromnaya River drain into the sea. Integral heavy-metal index calculations showed that this area is the most polluted in the Uglovoy Bay. Other significantly polluted areas were identified off the Zima Yuzhnaya settlement in the mouth of the bay and in vicinity of the low-level bridge.

Utilizing NASA Earth Observations to Assess Impacts of Hurricanes Andrew and Irma on Mangrove Forests in Biscayne Bay National Park, FL

NASA Astrophysics Data System (ADS)

Kumar, A.; Weber, S.; Remillard, C.; Escobar Pardo, M. L.; Hashemi Tonekaboni, N.; Cameron, C.; Linton, S.; Rickless, D.; Rivero, R.; Madden, M.

2017-12-01

Extreme weather events, such as hurricanes, pose major threats to coastal communities around the globe. However, mangrove forests along coastlines act as barriers and subdue the impacts associated with these catastrophic events. The Biscayne Bay National Park mangrove forest located near the city of Miami Beach was recently affected by the category four hurricane Irma in September of 2017. This study analyzed the impact of Hurricane Irma on Biscayne Bay National Park mangroves. Several remote sensing datasets including Landsat 8 Operational Land Imager (OLI), Sentinel 2-Multi Spectral Imager (MSI), PlanetScope, and aerial imagery were utilized to assess pre-and post-hurricane conditions. The high-resolution aerial imagery and PlanetScope data were used to map damaged areas within the national park. Additionally, Landsat 8 OLI and Sentinel-2 MSI data were utilized to estimate changes in biophysical parameters, including gross primary productivity (GPP), before and after Hurricane Irma. This project also examined damages associated with Hurricane Andrew (1992) using historical Landsat 5 Thematic Mapper (TM) data. These results were compared to GPP estimates following Hurricane Irma and suggested that Hurricane Andrew's impact was greater than that of Irma in Biscayne Bay National Park. The results of this study will help to enhance the mangrove health monitoring and shoreline management programs led by officials at the City of Miami Beach Public Works Department.

Florida Bay: A history of recent ecological changes

USGS Publications Warehouse

Fourqurean, J.W.; Robblee, M.B.

1999-01-01

Florida Bay is a unique subtropical estuary at the southern tip of the Florida peninsula. Recent ecological changes (seagrass die-off, algal blooms, increased turbidity) to the Florida Bay ecosystem have focused the attention of the public, commercial interests, scientists, and resource managers on the factors influencing the structure and function of Florida Bay. Restoring Florida Bay to some historic condition is the goal of resource managers, but what is not clear is what an anthropogenically-unaltered Florida Bay would look like. While there is general consensus that human activities have contributed to the changes occurring in the Florida Bay ecosystem, a high degree of natural system variability has made elucidation of the links between human activity and Florida Bay dynamics difficult. Paleoecological analyses, examination of long-term datasets, and directed measurements of aspects of the ecology of Florida Bay all contribute to our understanding of the behavior of the bay, and allow quantification of the magnitude of the recent ecological changes with respect to historical variability of the system.

ON THE WIND-INDUCED EXCHANGE BETWEEN INDIAN RIVER BAY, DELAWARE AND THE ADJACENT CONTINENTAL SHELF. (R826945)

EPA Science Inventory

The structure of the wind-induced exchange between Indian River Bay, Delaware and the adjacent continental shelf is examined based on current measurements made at the Indian River Inlet which represents the only conduit of exchange between the bay and the coastal ocean. Local ...

Attenuation of Storm Surge Flooding By Wetlands in the Chesapeake Bay: An Integrated Geospatial Framework Evaluating Impacts to Critical Infrastructure

NASA Astrophysics Data System (ADS)

Khalid, A.; Haddad, J.; Lawler, S.; Ferreira, C.

2014-12-01

Areas along the Chesapeake Bay and its tributaries are extremely vulnerable to hurricane flooding, as evidenced by the costly effects and severe impacts of recent storms along the Virginia coast, such as Hurricane Isabel in 2003 and Hurricane Sandy in 2012. Coastal wetlands, in addition to their ecological importance, are expected to mitigate the impact of storm surge by acting as a natural protection against hurricane flooding. Quantifying such interactions helps to provide a sound scientific basis to support planning and decision making. Using storm surge flooding from various historical hurricanes, simulated using a coupled hydrodynamic wave model (ADCIRC-SWAN), we propose an integrated framework yielding a geospatial identification of the capacity of Chesapeake Bay wetlands to protect critical infrastructure. Spatial identification of Chesapeake Bay wetlands is derived from the National Wetlands Inventory (NWI), National Land Cover Database (NLCD), and the Coastal Change Analysis Program (C-CAP). Inventories of population and critical infrastructure are extracted from US Census block data and FEMA's HAZUS-Multi Hazard geodatabase. Geospatial and statistical analyses are carried out to develop a relationship between wetland land cover, hurricane flooding, population and infrastructure vulnerability. These analyses result in the identification and quantification of populations and infrastructure in flooded areas that lie within a reasonable buffer surrounding the identified wetlands. Our analysis thus produces a spatial perspective on the potential for wetlands to attenuate hurricane flood impacts in critical areas. Statistical analysis will support hypothesis testing to evaluate the benefits of wetlands from a flooding and storm-surge attenuation perspective. Results from geospatial analysis are used to identify where interactions with critical infrastructure are relevant in the Chesapeake Bay.

AN "ENVIRO-INFORMATIC" ASSESSMENT OF SAGINAW BAY (LAKE HURON, USA) PHYTOPLANKTON: DATA-DRIVEN CHARACTERIZATION AND MODELING OF MICROCYSTIS (CYANOPHYTA)(1).

PubMed

Millie, David F; Fahnenstiel, Gary L; Weckman, Gary R; Klarer, David M; Dyble, Julianne; Vanderploeg, Henry A; Fishman, Daniel B

2011-08-01

Phytoplankton and Microcystis aeruginosa (Kütz.) Kütz. biovolumes were characterized and modeled, respectively, with regard to hydrological and meteorological variables during zebra mussel invasion in Saginaw Bay (1990-1996). Total phytoplankton and Microcystis biomass within the inner bay were one and one-half and six times greater, respectively, than those of the outer bay. Following mussel invasion, mean total biomass in the inner bay decreased 84% but then returned to its approximate initial value. Microcystis was not present in the bay during 1990 and 1991 and thereafter occurred at/in 52% of sample sites/dates with the greatest biomass occurring in 1994-1996 and within months having water temperatures >19°C. With an overall relative biomass of 0.03 ± 0.01 (mean + SE), Microcystis had, at best, a marginal impact upon holistic compositional dynamics. Dynamics of the centric diatom Cyclotella ocellata Pant. and large pennate diatoms dominated compositional dissimilarities both inter- and intra-annually. The environmental variables that corresponded with phytoplankton distributions were similar for the inner and outer bays, and together identified physical forcing and biotic utilization of nutrients as determinants of system-level biomass patterns. Nonparametric models explained 70%-85% of the variability in Microcystis biovolumes and identified maximal biomass to occur at total phosphorus (TP) concentrations ranging from 40 to 45 μg · L(-1) . From isometric projections depicting modeled Microcystis/environmental interactions, a TP concentration of <30 μg · L(-1) was identified as a desirable contemporary "target" for management efforts to ameliorate bloom potentials throughout mussel-impacted bay waters. © 2011 Phycological Society of America.

Biofuels and the bay: Characterizing health and ecosystem impacts in the Chesapeake

EPA Science Inventory

The global climate crisis has stimulated the search for alternative fuels. Biofuels have been the focus of a recent report by the Chesapeake Bay Commission that evaluated alternative fuel development efforts in the local area. Already under stress from anthropomorphic factors,...

Scientific Basis for Assessment of Nutrient Impacts on San Francisco Bay

EPA Science Inventory

San Francisco Bay (SFB) is a large, nutrient-enriched estuary that appears resistant to symptoms of nutrient over-enrichment, such as high phytoplankton biomass and hypoxia. This resistance traces to high turbidity, strong tidal mixing, and grazing that limit production and accum...

Preventing Pollution to Local Waters, Bay; Preserving Historic Natural Bridge in Virginia

EPA Pesticide Factsheets

In helping to preserve one of the oldest tourist destinations in the country – a spectacular natural land bridge in Virginia – EPA funding is protecting the surrounding land from development that would have impacted local waters and the Chesapeake Bay.

Pollution risk assessment of oil spill accidents in Garorim Bay of Korea.

PubMed

Lee, Moonjin; Jung, Jung-Yeul

2015-11-15

This study presents a model to assess the oil spill risk in Garorim Bay in Korea, where large-scale oil spill accidents frequently occur. The oil spill risk assessment is carried out by using two factors: 1) The impact probability of the oil spill, and 2) the first impact time of the oil that has been spilt. The risk assessment is conducted for environmentally sensitive areas, such as the coastline and aquaculture farms in the Garorim Bay area. Finally, Garorim Bay is divided into six subareas, and the risks of each subarea are compared with one another to identify the subarea that is most vulnerable to an oil spill accident. These results represent an objective and comprehensive oil spill risk level for a specific region. The prediction of the oil spill spread is based on real-time sea conditions and can be improved by integrating our results, especially when sea conditions are rapidly changing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Distribution of radionuclides in a marine sediment core off the waterspout of the nuclear power plants in Daya Bay, northeastern South China Sea.

PubMed

Zhou, Peng; Li, Dongmei; Li, Haitao; Fang, Hongda; Huang, Chuguang; Zhang, Yusheng; Zhang, Hongbiao; Zhao, Li; Zhou, Junjie; Wang, Hua; Yang, Jie

2015-07-01

A sediment core was collected and dated using (210)Pbex dating method off the waterspout of nuclear power base of Daya Bay, northeastern South China Sea. The γ-emitting radionuclides were analyzed using HPGe γ spectrometry, gross alpha and beta radioactivity as well as other geochemical indicators were deliberated to assess the impact of nuclear power plants (NPP) operation and to study the past environment changes. It suggested that NPP provided no new radioactivity source to sediment based on the low specific activity of (137)Cs. Two broad peaks of TOC, TC and LOI accorded well with the commercial operations of Daya Bay NPP (1994.2 and 1994.5) and LNPP Phase I (2002.5 and 2003.3), implying that the mass input of cooling water from NPP may result into a substantial change in the ecological environment and Daya Bay has been severely impacted by human activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

Polychlorinated naphthalenes (PCNs) in riverine and marine sediments of the Laizhou Bay area, North China.

PubMed

Pan, Xiaohui; Tang, Jianhui; Chen, Yingjun; Li, Jun; Zhang, Gan

2011-12-01

PCN congeners were analyzed in marine and riverine sediments of the Laizhou Bay area, North China. Concentrations of PCNs ranged from 0.12 to 5.1 ng g(-)(1) dry weight (dw) with a mean value of 1.1 ng g(-)(1) dw. The levels of PCNs varied largely, with industrial group approximately ten folds higher than those of the rural in riverine sediment. A strong impact by direct discharge from local factories was suggested. Similar compositional profiles were found within groups. High resemblance of compositional profiles between industrial samples and Halowax 1014 was observed. It was indicated that PCNs in riverine sediments were mainly from release of industrial usage, with additional contributions from industrial thermal process at certain sites. In marine sediments, it was suggested that PCNs along the coast of Laizhou Bay were mainly controlled by riverine input. While in the central bay, PCN distributions were possibly impacted by combined multiple factors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Geologic columns for the ICDP-USGS Eyreville A and B cores, Chesapeake Bay impact structure: Sediment-clast breccias, 1096 to 444 m depth

USGS Publications Warehouse

Edwards, L.E.; Powars, D.S.; Gohn, G.S.; Dypvik, H.

2009-01-01

The Eyreville A and B cores, recovered from the "moat" of the Chesapeake Bay impact structure, provide a thick section of sediment-clast breccias and minor stratified sediments from 1095.74 to 443.90 m. This paper discusses the components of these breccias, presents a geologic column and descriptive lithologic framework for them, and formalizes the Exmore Formation. From 1095.74 to ??867 m, the cores consist of nonmarine sediment boulders and sand (rare blocks up to 15.3 m intersected diameter). A sharp contact in both cores at ??867 m marks the lowest clayey, silty, glauconitic quartz sand that constitutes the base of the Exmore Formation and its lower diamicton member. Here, material derived from the upper sediment target layers, as well as some impact ejecta, occurs. The block-dominated member of the Exmore Formation, from ??855-618.23 m, consists of nonmarine sediment blocks and boulders (up to 45.5 m) that are juxtaposed complexly. Blocks of oxidized clay are an important component. Above 618.23 m, which is the base of the informal upper diamicton member of the Exmore Formation, the glauconitic matrix is a consistent component in diamicton layers between nonmarine sediment clasts that decrease in size upward in the section. Crystalline-rock clasts are not randomly distributed but rather form local concentrations. The upper part of the Exmore Formation consists of crudely fining-upward sandy packages capped by laminated silt and clay. The overlap interval of Eyreville A and B (940-??760 m) allows recognition of local similarities and differences in the breccias. ?? 2009 The Geological Society of America.

Treated wastewater effluent as a source of pyrethroids and fipronil at todos santos bay, Mexico: Its impact on sediments and organisms.

PubMed

Hernández-Guzmán, Félix Augusto; Macías-Zamora, José Vinicio; Ramírez-Álvarez, Nancy; Alvarez-Aguilar, Arturo; Quezada-Hernández, Cristina; Fonseca, Ana Paula

2017-11-01

Pyrethroids are insecticides widely used to control pests and disease vectors in residential areas and agricultural lands. Pyrethroids are emerging pollutants, and their use is a growing concern because of their toxicity potential to aquatic organisms. Todos Santos Bay and the Punta Banda estuary, 2 coastal bodies located to the south of the Southern California Bight, were studied to establish a baseline of the current conditions of pollution by pyrethroids and fipronil. Eight pyrethroids, along with fipronil and its 2 metabolites, were determined in effluents from wastewater-treatment plants (n = 3), surface sediments (n = 32), and 3 locations with mussels (Mytilus californianus, n = 9). Bifenthrin, permethrin, and cypermethrin were the most common pyrethroids found in the study areas and were widespread in sediments, mussels, and wastewater-treated effluents. Fipronil and its metabolites were detected in mussels and wastewater-treated effluents only. Total pyrethroid concentrations in sediments ranged from 0.04 to 1.95 ng/g dry weight in the Punta Banda estuary (n = 13) and from 0.07 to 6.62 ng/g dry weight in Todos Santos Bay (n = 19). Moreover, total pyrethroids in mussels ranged from 1.19 to 6.15 ng/g wet weight. Based on the toxic unit data calculated for pyrethroids and fipronil for Eohaustorius estuarius and Hyalella azteca, little to no impact is expected to the benthic population structure. Environ Toxicol Chem 2017;36:3057-3064. © 2017 SETAC. © 2017 SETAC.

Evaluating the Addition of a Dinoflagellate Phytoplankton Functional Type Using Radiance Anomalies for Monterey Bay, CA

NASA Astrophysics Data System (ADS)

Houskeeper, H. F.; Kudela, R. M.

2016-12-01

Ocean color sensors have enabled daily, global monitoring of phytoplankton productivity in the world's oceans. However, to observe key structures such as food webs, or to identify regime shifts of dominant species, tools capable of distinguishing between phytoplankton functional types using satellite remote sensing reflectance are necessary. One such tool developed by Alvain et al. (2005), PHYSAT, successfully linked four phytoplankton functional types to chlorophyll-normalized remote sensing spectra, or radiance anomalies, in case-1 waters. Yet this tool was unable to characterize dinoflagellates because of their ubiquitous background presence in the open ocean. We employ a radiance anomaly technique based on PHYSAT to target phytoplankton functional types in Monterey Bay, a region where dinoflagellate populations are larger and more variable than in open ocean waters, and thus where they may be viable targets for satellite remote sensing characterization. We compare with an existing Santa Cruz Wharf photo-pigment time series spanning from 2006 to the present to regionally ground-truth the method's predictions, and we assess its accuracy in characterizing dinoflagellates, a phytoplankton group that impacts the region's fish stocks and water quality. For example, an increase in dinoflagellate abundance beginning in 2005 led to declines in commercially important fish stocks that persisted throughout the following year. Certain species of dinoflagellates in Monterey Bay are also responsible for some of the harmful algal bloom events that negatively impact the shellfish industry. Moving toward better tools to characterize phytoplankton blooms is important for understanding ecosystem shifts, as well as protecting human health in the surrounding areas.

Long-term simulation of vertical transport process and its impact on bottom DO in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Du, J.; Shen, J.

2016-02-01

Hypoxia in coastal waters is a widespread phenomenon that appears to have been growing globally for at least 60 years. The fact that physical transport processes and biological processes are equally important in determining the bottom DO in Chesapeake Bay is commonly agreed. However, the quantitative impact of physical transport processes is rarely documented. In this study, we use a timescale, vertical exchange time (VET), to quantify the impact of all physical processes that might have on the bottom DO. Simulation of VET from 1985 to 2012 is conducted and the monthly observed DO data along the deep channel in the Bay's main stem is collected. A conceptual bottom DO budget model is applied, using the VET to quantify the physical condition and net oxygen consumption rate to quantify biological activities. The DO budget model results show that the interannual variations of physical conditions accounts for 88.8% of the interannual variations of observed DO. The high similarity between the VET spatial pattern and the observed DO suggests that physical processes play a key role in regulating the DO condition. Model results also show that long-term VET has a slight increase in summer, but no statistically significant trend is found. Correlations among southerly wind strength, North Atlantic Oscillation index, and VET demonstrate that the physical condition in the Chesapeake Bay is highly controlled by the large-scale climate variation. The relationship is most significant during the summer, when the southerly wind dominates throughout the Chesapeake Bay.

Reduction of flatfish habitat as a consequence of the proliferation of an invasive mollusc

NASA Astrophysics Data System (ADS)

Kostecki, C.; Rochette, S.; Girardin, R.; Blanchard, M.; Desroy, N.; Le Pape, O.

2011-03-01

Coastal bays provide habitats for juveniles and adults of many marine species. Mont Saint-Michel Bay (MSMB, France) hosts a highly diversified fish community and constitutes one of the most important nursery grounds for many commercially exploited marine species, such as sea bass, flatfish, clupeids and rays in the English Channel. Besides, MSMB also suffers from the massive invasion of an exotic mollusc, the American slipper-limpet ( Crepidula fornicata, L.). This species arrived four decades ago and now represents the main filter-feeder biomass in the bay (150 Mt), an order of magnitude larger than local farmed and natural shellfishes. Recent analyses underlined the impact of this small gastropod on the trophic structure of this bay and its negative influence on juvenile sole densities in the nursery grounds. The present study uses a geostatistical approach to explore the effect of the extension of the slipper-limpet on flatfish (common sole Solea solea, L.; plaice Pleuronectes platessa, L.; brill Scophthalmus rhombus, L. and flounder Platichthys flesus, L.) spatial distribution. Data collected during survey of the MSMB at the end of the 1970s and three decades later have been used to build interpolated maps of (1) slipper-limpet and (2) flatfish spatial distributions. Slipper-limpets were concentrated in a small area, in the western part of the MSMB, in the 1970s while today they occupy half of the bay. This rapid proliferation led to the decrease of available surface for flatfishes, which previously occupied the whole bay and are now restricted to its eastern part. The present study highlighted that the negative influence on fish habitat in MSMB is apparently more related to changes in the substratum than to trophic interactions. This invasion has possible consequences on flatfish population renewal at a large scale and may also damage other benthic or demersal species, such as rays.

Reducing Aerodynamic Drag on Empty Open Cargo Vehicles

NASA Technical Reports Server (NTRS)

Ross, James C.; Storms, Bruce L.; Dzoan, Dan

2009-01-01

Some simple structural modifications have been demonstrated to be effective in reducing aerodynamic drag on vehicles that have empty open cargo bays. The basic idea is to break up the airflow in a large open cargo bay by inserting panels to divide the bay into a series of smaller bays. In the case of a coal car, this involves inserting a small number (typically between two and four) of vertical full-depth or partial-depth panels.

Mobile remote manipulator vehicle system

NASA Technical Reports Server (NTRS)

Bush, Harold G. (Inventor); Mikulas, Martin M., Jr. (Inventor); Wallsom, Richard E. (Inventor); Jensen, J. Kermit (Inventor)

1987-01-01

A mobile remote manipulator system is disclosed for assembly, repair and logistics transport on, around and about a space station square bay truss structure. The vehicle is supported by a square track arrangement supported by guide pins integral with the space station truss structure and located at each truss node. Propulsion is provided by a central push-pull drive mechanism that extends out from the vehicle one full structural bay over the truss and locks drive rods into the guide pins. The draw bar is now retracted and the mobile remote manipulator system is pulled onto the next adjacent structural bay. Thus, translation of the vehicle is inchworm style. The drive bar can be locked onto two guide pins while the extendable draw bar is within the vehicle and then push the vehicle away one bay providing bidirectional push-pull drive. The track switches allow the vehicle to travel in two orthogonal directions over the truss structure which coupled with the bidirectional drive, allow movement in four directions on one plane. The top layer of this trilayered vehicle is a logistics platform. This platform is capable of 369 degees of rotation and will have two astronaut foot restraint platforms and a space crane integral.

Contamination assessment in microbiological sampling of the Eyreville core, Chesapeake Bay impact structure

USGS Publications Warehouse

Gronstal, A.L.; Voytek, M.A.; Kirshtein, J.D.; Von der, Heyde; Lowit, M.D.; Cockell, C.S.

2009-01-01

Knowledge of the deep subsurface biosphere is limited due to difficulties in recovering materials. Deep drilling projects provide access to the subsurface; however, contamination introduced during drilling poses a major obstacle in obtaining clean samples. To monitor contamination during the 2005 International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) deep drilling of the Chesapeake Bay impact structure, four methods were utilized. Fluorescent microspheres were used to mimic the ability of contaminant cells to enter samples through fractures in the core material during retrieval. Drilling mud was infused with a chemical tracer (Halon 1211) in order to monitor penetration of mud into cores. Pore water from samples was examined using excitation-emission matrix (EEM) fl uorescence spectroscopy to characterize dissolved organic carbon (DOC) present at various depths. DOC signatures at depth were compared to signatures from drilling mud in order to identify potential contamination. Finally, microbial contaminants present in drilling mud were identified through 16S ribosomal deoxyribonucleic acid (rDNA) clone libraries and compared to species cultured from core samples. Together, these methods allowed us to categorize the recovered core samples according to the likelihood of contamination. Twenty-two of the 47 subcores that were retrieved were free of contamination by all the methods used and were subsequently used for microbiological culture and culture-independent analysis. Our approach provides a comprehensive assessment of both particulate and dissolved contaminants that could be applied to any environment with low biomass. ?? 2009 The Geological Society of America.

Preparation for Testing a Multi-Bay Box Subjected to Combined Loads

NASA Technical Reports Server (NTRS)

Rouse, Marshall; Jegley, Dawn

2015-01-01

The COmbined Loads Test System (COLTS) facility at NASA Langley Research Center provides a test capability to help develop validated structures technologies. The test machine was design to accommodate a range of fuselage structures and wing sections and subject them to both quasistatic and cyclic loading conditions. The COLTS facility is capable of testing fuselage barrels up to 4.6 m in diameter and 13.7 m long with combined mechanical, internal pressure, and thermal loads. The COLTS facility is currently being prepared to conduct a combined mechanical and pressure loading for a multi-bay pressure box to experimentally verify the structural performance of a composite structure which is 9.1 meters long and representative of a section of a hybrid wing body fuselage section in support of the Environmentally Responsible Aviation Project at NASA. This paper describes development of the multi-bay pressure box test using the COLTS facility. The multi-bay test article will be subjected to mechanical loads and internal pressure loads up to design ultimate load. Mechanical and pressure loads will be applied independently in some tests and simultaneously in others.

Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

USGS Publications Warehouse

Barnard, Patrick L.; Erikson, Li H.; Elias, Edwin P.L.; Dartnell, Peter

2013-01-01

The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7-8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

USGS Publications Warehouse

Barnard, Patrick L.; Erikson, Li H.; Elias, Edwin P.L.; Dartnell, Peter; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7–8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

Rock-avalanche and ocean-resurge deposits in the late Eocene Chesapeake Bay impact structure: Evidence from the ICDP-USGS Eyreville cores, Virginia, USA

USGS Publications Warehouse

Gohn, G.S.; Powars, D.S.; Dypvik, H.; Edwards, L.E.

2009-01-01

An unusually thick section of sedimentary breccias dominated by target-sediment clasts is a distinctive feature of the late Eocene Chesapeake Bay impact structure. A cored 1766-m-deep section recovered from the central part of this marine-target structure by the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) drilling project contains 678 m of these breccias and associated sediments and an intervening 275-m-thick granite slab. Two sedimentary breccia units consist almost entirely of Cretaceous nonmarine sediments derived from the lower part of the target sediment layer. These sediments are present as coherent clasts and as autoclastic matrix between the clasts. Primary (Cretaceous) sedimentary structures are well preserved in some clasts, and liquefaction and fluidization structures produced at the site of deposition occur in the clasts and matrix. These sedimentary breccias are interpreted as one or more rock avalanches from the upper part of the transient-cavity wall. The little-deformed, unshocked granite slab probably was transported as part of an extremely large slide or avalanche. Water-saturated Cretaceous quartz sand below the slab was transported into the seafloor crater prior to, or concurrently with, the granite slab. Two sedimentary breccia units consist of polymict diamictons that contain cobbles, boulders, and blocks of Cretaceous nonmarine target sediments and less common shocked-rock and melt ejecta in an unsorted, unstratified, muddy, fossiliferous, glauconitic quartz matrix. Much of the matrix material was derived from Upper Cretaceous and Paleogene marine target sediments. These units are interpreted as the deposits of debris flows initiated by the resurge of ocean water into the seafloor crater. Interlayering of avalanche and debris-flow units indicates a partial temporal overlap of the earlier avalanche and later resurge processes. A thin unit of stratified turbidite deposits and overlying laminated fine-grained deposits at the top of the section represents the transition to normal shelf sedimentation. ?? 2009 The Geological Society of America.

Long-term isolation and local adaptation in Palau's Nikko Bay help corals thrive in acidic waters

NASA Astrophysics Data System (ADS)

Golbuu, Yimnang; Gouezo, Marine; Kurihara, Haruko; Rehm, Lincoln; Wolanski, Eric

2016-09-01

The reefs in Palau's Nikko Bay live in seawater with low pH that is similar to conditions predicted for 2100 because of ocean acidification. Nevertheless, the reefs at Nikko Bay have high coral cover and high diversity. We hypothesize that the low-pH environment in Nikko Bay is caused by low flushing rates, which causes long-term isolation and local adaptation. To test this hypothesis, we modeled the water circulation in and around Nikko Bay. Model results show that average residence time is 71 d, which is ten times the residence time on fore-reef habitats. The long residence time restricts the exchange of coral larvae in the bay with adjacent reefs, allowing persistent selection for tolerant traits and local adaptation. The corals in Nikko Bay are also more susceptible to local pollution because the waters are poorly flushed. Therefore, local management must focus on minimizing human impacts such as dredging, overfishing and pollution in the bay, which would compromise the condition of the corals that have already adapted to low-pH conditions.

Occurrence and distribution of antibiotics in coastal water of the Bohai Bay, China: impacts of river discharge and aquaculture activities.

PubMed

Zou, Shichun; Xu, Weihai; Zhang, Ruijie; Tang, Jianhui; Chen, Yingjun; Zhang, Gan

2011-10-01

The presence of 21 antibiotics in six different groups was investigated in coastal water of the Bohai Bay. Meantime, to illuminate the potential effects caused by the river discharge and aquaculture activities, wastewater from three breeding plants and surface water from six rivers flowing into the Bohai Bay were also analyzed for the selected antibiotics. The result revealed that measured antibiotics in the North Bobai Bay were generally higher than those in the South, highlighting the remarkable effects of high density of human activities on the exposure of antibiotics in environment. The antibiotics found in the six rivers were generally higher than those in the Bohai Bay reflecting the important antibiotics source of river discharge. This study reveals that the high consumption of some antibiotics in aquaculture activities may pose high ecological risk to the bay. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hydrodynamics and water quality models applied to Sepetiba Bay

NASA Astrophysics Data System (ADS)

Cunha, Cynara de L. da N.; Rosman, Paulo C. C.; Ferreira, Aldo Pacheco; Carlos do Nascimento Monteiro, Teófilo

2006-10-01

A coupled hydrodynamic and water quality model is used to simulate the pollution in Sepetiba Bay due to sewage effluent. Sepetiba Bay has a complicated geometry and bottom topography, and is located on the Brazilian coast near Rio de Janeiro. In the simulation, the dissolved oxygen (DO) concentration and biochemical oxygen demand (BOD) are used as indicators for the presence of organic matter in the body of water, and as parameters for evaluating the environmental pollution of the eastern part of Sepetiba Bay. Effluent sources in the model are taken from DO and BOD field measurements. The simulation results are consistent with field observations and demonstrate that the model has been correctly calibrated. The model is suitable for evaluating the environmental impact of sewage effluent on Sepetiba Bay from river inflows, assessing the feasibility of different treatment schemes, and developing specific monitoring activities. This approach has general applicability for environmental assessment of complicated coastal bays.

Baseline aquatic contamination and endocrine status in a resident fish of Biscayne National Park

USGS Publications Warehouse

Bargar, Timothy A.; Whelan, Kevin R.T.; Alvarez, David; Echols, Kathy R.; Peterman, Paul H.

2017-01-01

Surface water, sediment, and fish from Biscayne Bay, coastal wetlands adjacent to the Bay, and canals discharging into the Bay were sampled for determination of baseline contamination in Biscayne National Park. While the number of contaminants detected in canal waters was greater during the wet season than the dry season, no seasonal difference was evident for Biscayne Bay or coastal wetland waters. Estrogen equivalency (as 17β-estradiol equivalents), as predicted by the Yeast Estrogen Screen, for extracts of passive water samplers deployed in canals and wetlands was elevated during the wet relative to the dry season. Generally, contamination in water, sediments, and fish was greater in the canals than in Biscayne Bay and the wetlands. Guideline levels for sediment contaminant were exceeded most frequently in canals relative to the coastal wetlands and the Bay. Further investigation is necessary to better understand the impact of contaminants in Biscayne National Park.

Collapse of an oyster fishery during a historic drought may provide insight into future effects of climate change on estuaries

NASA Astrophysics Data System (ADS)

Havens, K. E.; Kane, A.

2016-02-01

In 2012 the oyster population in Apalachicola Bay, Florida suddenly collapsed. The catastrophic event, which had severe impacts on the local economy, coincided with two years of record low rainfall over the watershed and the lowest river flows into the estuary in 89 years. Elevated salinity in the bay allowed marine predators, parasites and pathogens from the Gulf of Mexico to increase in abundance and impact the oyster population. Population modeling indicated that the proximal cause of the collapse was high juvenille mortality. Ecosystem modeling (using ECOSPACE) indicated that because the system also had considerably degraded habitat, recovery of oyster harvest to pre-impact levels would require both (a) substantially reduced harvest pressure for a period of two years and (b) restoration of at least 1,000 acres of oyster reef. Given that in the future climate change may result both in greater saltwater inputs (due to sea level rise) and increased frequency and/or intensity of droughts, the effects observed in Apalachicola Bay can provide a 'lens' into the future in regard to estuarine impacts.

Commencement Bay Cumulative Impact Study: Historic Review of Special Aquatic Sites

DTIC Science & Technology

1991-05-04

is generally defined as a geographic region of south Puget Sound in Washington State extending from Brown’s Point to Point Defiance. (Figure-10. it...amount of sediment load. 2 2 Area enlarged Commencement Bay Cumulative Impacts Study (U Puget Sound 0 0 3.0 600E,0 Point) Figureat 1. Study AreaMa...the Puget Sound Environmental Atlas was produced under funding from the Seattle District Corps of Engineers, EPA, and the Puget Sound Water Quality

STS-114 Micrometeoroid/Orbital Debris (MMOD) Post-Flight Assessment

NASA Technical Reports Server (NTRS)

Hyde, J.; Bernhard, R.; Christiansen, E.

2007-01-01

NASA Johnson Space Center (JSC) personnel assisted Kennedy Space Center (KSC) inspection teams in the identification of 41 micrometeoroid/orbital debris (MMOD) impact sites on the OV-103 vehicle (Discovery) during STS-114 postflight inspections. There were 14 MMOD impacts reported on the crew module windows (Figure 1). The largest impact feature, a 6.6 mm x 5.8 mm crater on window #4, was caused by a particle with an estimated diameter of 0.22 mm (Figure 2). This impact was among the largest ever recorded on a crew module window. The window was removed and replaced. Scanning Electron Microscope/Energy Dispersive X-ray (SEM/EDX) analysis of dental mold samples from the impact site to determine particle origin was inconclusive, possibly due to contamination picked up on the ferry flight from Edwards Air Force Base to KSC. The radiators on the inside of the payload bay doors sustained 19 impacts (Figure 3) with one of the impacts causing a face sheet perforation. The 0.61 mm diameter hole was produced by a particle with an estimated diameter of 0.4 mm, which approaches the 0.5-mm critical particle diameter of the wing leading edge reinforced carbon-carbon (RCC) panel high-temperature regions (Zone 3, Figure 4) that was established during Return to Flight testing of the RCC panels. An inspection of the payload bay door exterior insulation (FRSI) revealed a 5.8 mm x 4.5 mm defect that was caused by an MMOD particle with unknown composition, as the sample obtained was contaminated. Figure 5 provides a summary of the exterior surface survey that was conducted following the STS-114 mission. Two windows were removed and replaced due to hypervelocity impact. Nineteen impacts were recorded on the payload bay door radiators, with one face sheet penetration. Three impact sites were identified on the FRSI. There were four hypervelocity impact sites detected on the wing leading edge RCC panels. One impact was detected on the top cover of the TPS sample box (TSB) payload that was mounted on a carrier in the aft portion of the payload bay.

Geologic columns for the ICDP-USGS Eyreville A and C cores, Chesapeake Bay impact structure: Postimpact sediments, 444 to 0 m depth

USGS Publications Warehouse

Edwards, L.E.; Powars, D.S.; Browning, J.V.; McLaughlin, P.P.; Miller, K.G.; ,; Kulpecz, A.A.; Elbra, T.

2009-01-01

A 443.9-m-thick, virtually undisturbed section of postimpact deposits in the Chesapeake Bay impact structure was recovered in the Eyreville A and C cores, Northampton County, Virginia, within the "moat" of the structure's central crater. Recovered sediments are mainly fine-grained marine siliciclastics, with the exception of Pleistocene sand, clay, and gravel. The lowest postimpact unit is the upper Eocene Chickahominy Formation (443.9-350.1 m). At 93.8 m, this is the maximum thickness yet recovered for deposits that represent the return to "normal marine" sedimentation. The Drummonds Corner beds (informal) and the Old Church Formation are thin Oligocene units present between 350.1 and 344.7 m. Above the Oligocene, there is a more typical Virginia coastal plain succession. The Calvert Formation (344.7-225.4 m) includes a thin lower Miocene part overlain by a much thicker middle Miocene part. From 225.4 to 206.0 m, sediments of the middle Miocene Choptank Formation, rarely reported in the Virginia coastal plain, are present. The thick upper Miocene St. Marys and Eastover Formations (206.0-57.8 m) appear to represent a more complete succession than in the type localities. Correlation with the nearby Kiptopeke core indicates that two Pliocene units are present: Yorktown (57.8-32.2 m) and Chowan River Formations (32.2-18.3 m). Sediments at the top of the section represent an upper Pleistocene channel-fill and are assigned to the Butlers Bluff and Occohannock Members of the Nassawadox Formation (18.3-0.6 m). ?? 2009 The Geological Society of America.

Bayes Factor Covariance Testing in Item Response Models.

PubMed

Fox, Jean-Paul; Mulder, Joris; Sinharay, Sandip

2017-12-01

Two marginal one-parameter item response theory models are introduced, by integrating out the latent variable or random item parameter. It is shown that both marginal response models are multivariate (probit) models with a compound symmetry covariance structure. Several common hypotheses concerning the underlying covariance structure are evaluated using (fractional) Bayes factor tests. The support for a unidimensional factor (i.e., assumption of local independence) and differential item functioning are evaluated by testing the covariance components. The posterior distribution of common covariance components is obtained in closed form by transforming latent responses with an orthogonal (Helmert) matrix. This posterior distribution is defined as a shifted-inverse-gamma, thereby introducing a default prior and a balanced prior distribution. Based on that, an MCMC algorithm is described to estimate all model parameters and to compute (fractional) Bayes factor tests. Simulation studies are used to show that the (fractional) Bayes factor tests have good properties for testing the underlying covariance structure of binary response data. The method is illustrated with two real data studies.

Effects of erosion control structures along a portion of the northern Chesapeake Bay shoreline

USGS Publications Warehouse

Zabawa, C.F.; Kerhin, R.T.; Bayley, S.

1981-01-01

A 6.500-meter reach of western Chesapeake Bay shoreline (lower Mayo Peninsula) lost about 1.1??106 cubic meters of sediment (equivalent to 170 cubic meters lost per meter of shoreline) between 1846 and 1932, when the first aerial photographs show the shoreline already substantially protected by a system of groins and intermittent bulkheading. These structures have eliminated the fastland as a source of erodable material, and have starved the supply of sand for littoral drift, thus limiting the extent of the beaches to the remaining groin fields. Volumes of sediment involved in these impacts are small in the overall sediment budget. Bulkheads produce no deficit in the budget since scouring of the beaches on their seaward sides makes up for the decreased erosion of protected fastland. Groins trap little of the potential littoral drift (computed to be about 104 cubic meters per meter of shoreline per year). The sand supply in the remaining beaches is nearly equivalent to the annual loss of sediment from the entire shoreline system due to the long-term rate of erosion of the shoreline and nearshore between 1846 and 1932. ?? 1981 Springer-Verlag New York Inc.

Spatial variation of phytoplankton community structure in Daya Bay, China.

PubMed

Jiang, Zhao-Yu; Wang, You-Shao; Cheng, Hao; Zhang, Jian-Dong; Fei, Jiao

2015-10-01

Daya Bay is one of the largest and most important gulfs in the southern coast of China, in the northern part of the South China Sea. The phylogenetic diversity and spatial distribution of phytoplankton from the Daya Bay surface water and the relationship with the in situ water environment were investigated by the clone library of the large subunit of ribulose-1, 5-bisphosphate carboxylase (rbcL) gene. The dominant species of phytoplankton were diatoms and eustigmatophytes, which accounted for 81.9 % of all the clones of the rbcL genes. Prymnesiophytes were widely spread and wide varieties lived in Daya Bay, whereas the quantity was limited. The community structure of phytoplankton was shaped by pH and salinity and the concentration of silicate, phosphorus and nitrite. The phytoplankton biomass was significantly positively affected by phosphorus and nitrite but negatively by salinity and pH. Therefore, the phytoplankton distribution and biomass from Daya Bay were doubly affected by anthropic activities and natural factors.

Geologic map of the San Francisco Bay region

USGS Publications Warehouse

Graymer, R.W.; Moring, B.C.; Saucedo, G.J.; Wentworth, C.M.; Brabb, E.E.; Knudsen, K. L.

2006-01-01

The rocks and fossils of the San Francisco Bay region reveal that the geology there is the product of millions of years at the active western margin of North America. The result of this history is a complex mosaic of geologic materials and structures that form the landscape. A geologic map is one of the basic tools to understand the geology, geologic hazards, and geologic history of a region.With heightened public awareness about earthquake hazards leading up to the 100th anniversary of the 1906 San Francisco earthquake, the U.S. Geological Survey (USGS) is releasing new maps of the San Francisco Bay Area designed to give residents and others a new look at the geologic history and hazards of the region. The “Geologic Map of the San Francisco Bay region” shows the distribution of geologic materials and structures, demonstrates how geologists study the age and origin of the rocks and deposits that we live on, and reveals the complicated geologic history that has led to the landscape that shapes the Bay Area.

Thatcher Bay, Washington, Nearshore Restoration Assessment

USGS Publications Warehouse

Breems, Joel; Wyllie-Echeverria, Sandy; Grossman, Eric E.; Elliott, Joel

2009-01-01

The San Juan Archipelago, located at the confluence of the Puget Sound, the Straits of Juan de Fuca in Washington State, and the Straits of Georgia, British Columbia, Canada, provides essential nearshore habitat for diverse salmonid, forage fish, and bird populations. With 408 miles of coastline, the San Juan Islands provide a significant portion of the available nearshore habitat for the greater Puget Sound and are an essential part of the regional efforts to restore Puget Sound (Puget Sound Shared Strategy 2005). The nearshore areas of the San Juan Islands provide a critical link between the terrestrial and marine environments. For this reason the focus on restoration and conservation of nearshore habitat in the San Juan Islands is of paramount importance. Wood-waste was a common by-product of historical lumber-milling operations. To date, relatively little attention has been given to the impact of historical lumber-milling operations in the San Juan Archipelago. Thatcher Bay, on Blakely Island, located near the east edge of the archipelago, is presented here as a case study on the restoration potential for a wood-waste contaminated nearshore area. Case study components include (1) a brief discussion of the history of milling operations. (2) an estimate of the location and amount of the current distribution of wood-waste at the site, (3) a preliminary examination of the impacts of wood-waste on benthic flora and fauna at the site, and (4) the presentation of several restoration alternatives for the site. The history of milling activity in Thatcher Bay began in 1879 with the construction of a mill in the southeastern part of the bay. Milling activity continued for more than 60 years, until the mill closed in 1942. Currently, the primary evidence of the historical milling operations is the presence of approximately 5,000 yd3 of wood-waste contaminated sediments. The distribution and thickness of residual wood-waste at the site was determined by using sediment coring and GIS-based interpolation techniques. Additionally, pilot studies were conducted to characterize in place sediment redox, organic composition, and sulfide impacts to nearshore flora and fauna. We found that the presence of wood-waste in Thatcher Bay may alter the quality of the benthic habitat by contributing to elevated levels of total organic composition (TOC) of the sediment. Increased TOC favors anaerobic respiration in marine sediments, and sulfide, a toxic by-product of this process, was found at levels as high as 17.5 mg L-1 in Thatcher Bay. The Thatcher Bay sulfide levels are several orders of magnitude higher than those known to impact benthic invertebrates. Eelgrass, Zostera marina, located on the western margin of Thatcher Bay, was surveyed by using underwater video surveys. This baseline distribution will in part be used to measure the impact of any future remediation efforts. Additionally, the distribution and survey data can provide an estimate of propagule source for future colonization of restored sediment. Three restoration alternatives were considered, and a ranking matrix was developed to score each alternative against site-specific and regional criteria. The process identified the removal of wood-waste from a water-based platform as the preferred alternative. Our multidisciplinary investigation identified the location, thickness, and potential impacts of wood-waste that has persisted in the nearshore environment of Thatcher Bay since at least 1942. We also provide a process to efficiently evaluate alternatives to remediate the impact of this historical disturbance and to potentially contribute to an increase of nearshore diversity and productivity at this site. Elements of this approach could inform restoration planning at similarly impacted sites throughout the region.

External impacts of an intraurban air transportation system in the San Francisco Bay area

NASA Technical Reports Server (NTRS)

Lu, J. Y.; Gebman, J. R.; Kirkwood, T. F.; Mcclure, P. T.; Stucker, J. P.

1972-01-01

The effects are studied of an intraurban V/STOL commuter system on the economic, social, and physical environment of the San Francisco Bay Area. The Bay Area was chosen mainly for a case study; the real intent of the analysis is to develop methods by which the effects of such a system could be evaluated for any community. Aspects of the community life affected include: income and employment, benefits and costs, noise, air pollution, and road congestion.

Tampa Bay Water Clarity Model (TBWCM): As a Predictive Tool

EPA Science Inventory

The Tampa Bay Water Clarity Model was developed as a predictive tool for estimating the impact of changing nutrient loads on water clarity as measured by secchi depth. The model combines a physical mixing model with an irradiance model and nutrient cycling model. A 10 segment bi...

Kingsbury Bay-Grassy Point Habitat Restoration Project: A health impact assessment-presentation

EPA Science Inventory

The St. Louis River Area of Concern is a large remediation site along the Minnesota and Wisconsin border. In the next phase of the clean-up, Minnesota Department of Natural Resources is undertaking a 200-acre wetland remediation and restoration project at Kingsbury Bay and Grassy...

Kingsbury Bay-Grassy Point Habitat Restoration Project: A Health Impact Assessment

EPA Science Inventory

The St. Louis River Area of Concern is a large remediation site along the Minnesota and Wisconsin border. In the next phase of the clean-up, Minnesota Department of Natural Resources is undertaking a 200-acre wetland remediation and restoration project at Kingsbury Bay and Grassy...

BENTHIC SUSPENSION FEEDERS IN PENSACOLA BAY, FL: PRELIMINARY STUDIES CONCERNING IMPACTS ON PHYTOPLANKTON THROUGH GRAZING

EPA Science Inventory

Cultural eutrophication in coastal habitats has become a crucial problem for resource managers and policymakers and a critical area of research in ecological science. Models of eutrophication have been developed for some coastal habitats (e.g., Chesapeake Bay), but research on ma...

BENTHIC SUSPENSION FEEDERS IN PENSACOLA BAY, FL: PRELIMINARY STUDIES CONCERNING IMPACTS ON PHYTOPLANKTON THROUGH GRAZING (ABSTRACT)

EPA Science Inventory

Cultural eutrophication in coastal habitats has become a crucial problem for resource managers and policymakers and a critical area of research in ecological science. Models of eutrophication have been developed for some coastal habitats (e.g., Chesapeake Bay), but research on ma...

NET ANTHROPOGENIC PHOSPHORUS INPUTS; SPATIAL AND TEMPORAL VARIABILITY IN THE CHESAPEAKE BAY REGION

EPA Science Inventory

Coastal watershed eutrophication has increasingly become a regional and global issue as larger proportions of the earth’s human population settle in coastal areas. Human activities on the land have severely impacted the water resources of the Chesapeake Bay, one of the world’s l...

Potential Climate-Induced Runoff Changes and Associated Uncertainty in Four Pacific Northwest Estuaries

EPA Science Inventory

As part of a larger investigation into potential impacts of climate change on estuarine habitats in the Pacific Northwest (PNW), we estimated changes in freshwater inputs into four estuaries. These were the Coquille River estuary, the South Slough of Coos Bay, and the Yaquina Bay...

Oil characterization and distribution in shoreline sediments of Pensacola Bay, Florida following the Deepwater Horizon spill

EPA Science Inventory

Barrier islands of Northwest Florida were heavily oiled during the Deepwater Horizon spill, but less is known about the impacts to the shorelines of the associated estuaries. Shoreline sediment oiling was investigated at 18 sites within the Pensacola Bay, Florida system prior to...

ASSESSMENT OF GROUNDWATER DISCHARGE AND SEWAGE IMPACT INTO SARASOTA BAY AND SUWANNEE RIVER ESTUARY

EPA Science Inventory

The ongoing objectives in Sarasota Bay are to 1) determine if the reduced water clarity and enriched 15N seagrass values are due to groundwater N inputs, 2) determine the effectiveness of geophysical reconnaissance methods in identifying zones of groundwater discharge under a var...

An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska (Final Report)

EPA Science Inventory

The Bristol Bay watershed in southwestern Alaska supports the largest sockeye salmon fishery in the world, is home to 25 federally recognized tribal governments, and contains large mineral resources. The potential for large-scale mining activities in the watershed has raised conc...

On the Half Shell: An Introduction to Oysters and Their Unique Structures and Function

ERIC Educational Resources Information Center

Frederick, J. Adam; Haines, Sarah; Romano, Christina; Takacs, Jacqueline

2017-01-01

The eastern oyster, "Crassostrea virginica," is an ecologically and economically important species in Chesapeake Bay. Oysters are ecologically unique in the Chesapeake Bay because they build a structure known as a bar or reef by attaching to one another over a 45 long period of time. They have been coined the "Ecological Engineers…

Examination of Below-Ground Structure and Soil Respiration Rates of Stable and Deteriorating Salt Marshes in Jamaica Bay (NY)

EPA Science Inventory

CAT scan imaging is currently being used to examine below-ground peat and root structure in cores collected from salt marshes of Jamaica Bay, part of the Gateway National Recreation Area (NY). CAT scans or Computer-Aided Tomography scans use X-ray equipment to produce multiple i...

Definition of ground test for verification of large space structure control

NASA Technical Reports Server (NTRS)

Seltzer, S. M.; Doane, G. B., III

1985-01-01

Directions regarding the analytical models were received. A counter balance arm with weights was added at the top of the ASTROMAST to offset the arm with the gimbals. In addition to this model, three more models were requested from MSFC: structure as in the revised model with the addition of lumped masses at bays 46 and 91 of the ASTROMAST; cantilevered cruciform structure with lumped masses at bays 46 and 91, and an all up cruciform structure with lumped masses at bays 46 and 91. Figures for each model and their corresponding natural frequencies and general mode shapes associated with these frequencies are included. The drawbar in use in the cruciform models must be incorporated into the antenna and ASTROMAST models. The total tensile load carrying capability of the ASTROMAST is approximately 840 pounds.

Hydrocode Simulations of the Chesapeake Bay Impact

NASA Technical Reports Server (NTRS)

Collins, G. S.; Melosh, H. J.

2004-01-01

The Chesapeake Bay Impact Crater (CBIC) formed about 35 million years ago (late Eocene), in a shallow marine environment (400-600 m water depth). The crater is complex and developed in a multi-layer, rheologically-variable target that comprised 400-1000 meters of soft, water-saturated sediments overlying crystalline basement. Seismic reflection data illustrates that the Chesapeake Bay crater morphology - often described as an "inverted sombrero" - is similar to other marine-target impact craters. It consists of a approx. 1 - 1.5-km deep, highly disturbed central crater, surrounded by a shallower, less deformed basin. The inner crater has a diameter of approx. 40 km; the edge of the outer basin extends to 85-km diameter. The morphological divide between the inner and outer crater is termed the inner ring or peak ring. Little is known about the nature of the inner ring. Seismic reflection data show that the underlying basement is modestly uplifted; however, it is unclear whether the pristine surface expression of the inner ring was elevated above the floor of the outer crater.

Shuttle Hypervelocity Impact Database

NASA Technical Reports Server (NTRS)

Hyde, James L.; Christiansen, Eric L.; Lear, Dana M.

2011-01-01

With three missions outstanding, the Shuttle Hypervelocity Impact Database has nearly 3000 entries. The data is divided into tables for crew module windows, payload bay door radiators and thermal protection system regions, with window impacts compromising just over half the records. In general, the database provides dimensions of hypervelocity impact damage, a component level location (i.e., window number or radiator panel number) and the orbiter mission when the impact occurred. Additional detail on the type of particle that produced the damage site is provided when sampling data and definitive analysis results are available. Details and insights on the contents of the database including examples of descriptive statistics will be provided. Post flight impact damage inspection and sampling techniques that were employed during the different observation campaigns will also be discussed. Potential enhancements to the database structure and availability of the data for other researchers will be addressed in the Future Work section. A related database of returned surfaces from the International Space Station will also be introduced.

Evaluating the Impacts of Mangrove Rehabilitation in Cogtong Bay, Philippines

NASA Astrophysics Data System (ADS)

Maliao, Ronald J.; Polohan, Bernice B.

2008-03-01

Marine Protected Areas (MPAs) have been hailed worldwide as vehicles toward sustainable development (SD) in coastal zones. The prominent model by which MPAs operate is through a comanagement approach, a shift from traditional top-down management. This paradigm shift must be reviewed continuously to evaluate its social and ecological impacts, thereby allowing adaptive management. We evaluated the perceived impacts of the Cogtong Bay Mangrove Rehabilitation Project (CBMRP; Philippines) by using 12 perception indicators categorized into 3 comanagement impact criteria (equity, efficiency, and sustainability). We also collected 16 contextual attributes of each respondent to determine the correlates of perceived impacts. Our results showed that there were significant improvements in all indicators under the efficiency criterion but mixed impacts in the equity and sustainability criteria. Access to resource and household income (equity) and fisheries abundance (sustainability) were perceived to have decreased during the last 15 years and were not expected to improve in the future. Stepwise multiple regression analysis showed that the asymmetries of the perceived impacts of the CBMRP were principally caused by disparities in perceptions by gender and by location (Candijay and Mabini). This highlighted the importance of cross-scale institutional linkages between Cogtong Bay municipalities to systematically address baywide management issues. Our results further demonstrated the necessity of integrating gender issues into the evaluation of MPA impacts to ensure a robust evaluation. Finally, we recommend that a rigorous evaluation of MPAs using a common set of impact indicators should be encouraged to allow comparison of studies both spatially and temporally.

Crustal structure of the coastal and marine San Francisco Bay region, California

USGS Publications Warehouse

Parsons, Tom

2002-01-01

In summary, these studies were carried out in an environment where background information on faults in the San Francisco Bay region was sought. Much of the structural information presented here comes from experiments of a style unlikely to be conducted by the USGS in the near future. Together, the chapters in this volume provide a structural framework for a major part of a complex strike-slip fault system.

Crustal structure of Baffin Bay from constrained 3-D gravity inversion and deformable plate tectonic models

NASA Astrophysics Data System (ADS)

Welford, J. Kim; Peace, Alexander L.; Geng, Meixia; Dehler, Sonya A.; Dickie, Kate

2018-05-01

Mesozoic to Cenozoic continental rifting, breakup, and spreading between North America and Greenland led to the opening, from south to north, of the Labrador Sea and eventually Baffin Bay between Baffin Island, northeast Canada, and northwest Greenland. Baffin Bay lies at the northern limit of this extinct rift, transform, and spreading system and remains largely underexplored. With the sparsity of existing crustal-scale geophysical investigations of Baffin Bay, regional potential field methods and quantitative deformation assessments based on plate reconstructions provide two means of examining Baffin Bay at the regional scale and drawing conclusions about its crustal structure, its rifting history, and the role of pre-existing structures in its evolution. Despite the identification of extinct spreading axes and fracture zones based on gravity data, insights into the nature and structure of the underlying crust have only been gleaned from limited deep seismic experiments, mostly concentrated in the north and east where the continental shelf is shallower and wider. Baffin Bay is partially underlain by oceanic crust with zones of variable width of extended continental crust along its margins. 3-D gravity inversions, constrained by bathymetric and depth to basement constraints, have generated a range of 3-D crustal density models that collectively reveal an asymmetric distribution of extended continental crust, approximately 25-30 km thick, along the margins of Baffin Bay, with a wider zone on the Greenland margin. A zone of 5 to 13 km thick crust lies at the centre of Baffin Bay, with the thinnest crust (5 km thick) clearly aligning with Eocene spreading centres. The resolved crustal thicknesses are generally in agreement with available seismic constraints, with discrepancies mostly corresponding to zones of higher density lower crust along the Greenland margin and Nares Strait. Deformation modelling from independent plate reconstructions using GPlates of the rifted margins of Baffin Bay was performed to gauge the influence of original crustal thickness and the width of the deformation zone on the crustal thicknesses obtained from the gravity inversions. These results show the best match with the results from the gravity inversions for an original unstretched crustal thickness of 34-36 km, consistent with present-day crustal thicknesses derived from teleseismic studies beyond the likely continentward limits of rifting around the margins of Baffin Bay. The width of the deformation zone has only a minimal influence on the modelled crustal thicknesses if the zone is of sufficient width that edge effects do not interfere with the main modelled domain.

Methodologies for Combined Loads Tests Using a Multi-Actuator Test Machine

NASA Technical Reports Server (NTRS)

Rouse, Marshall

2013-01-01

The NASA Langley COmbined Loads Test System (COLTS) Facility was designed to accommodate a range of fuselage structures and wing sections and subject them to both quasistatic and cyclic loading conditions. Structural tests have been conducted in COLTS that address structural integrity issues of metallic and fiber reinforced composite aerospace structures in support of NASA Programs (i.e. the Aircraft Structural Integrity (ASIP) Program, High-Speed-Research program and the Supersonic Project, NASA Engineering and Safety Center (NESC) Composite Crew Module Project, and the Environmentally Responsible Aviation Program),. This paper presents experimental results for curved panels subjected to mechanical and internal pressure loads using a D-box test fixture. Also, results are presented that describe use of a checkout beam for development of testing procedures for a combined mechanical and pressure loading test of a Multi-bay box. The Multi-bay box test will be used to experimentally verify the structural performance of the Multi-bay box in support of the Environmentally Responsible Aviation Project at NASA Langley.

Generation of periodic intrusions at Suruga Bay when the Kuroshio follows a large meandering path

NASA Astrophysics Data System (ADS)

Katsumata, Takaaki

2016-07-01

We measured the vertical profiles of currents at the eastern mouth of the Suruga Bay using a moored acoustic Doppler current profiler (ADCP). Currents vertical profiles were found to be mostly barotropic in structure when intrusions occurred at the eastern mouth of the bay. Warm-water intrusions at the Suruga Bay and sea level elevations at the bay and at islands on the Izu Ridge located off the bay have the same period of 26 days. The temporal variation in the sea levels occurs in response to Kuroshio frontal waves, and the two phases are consistent. The sea level rise propagates from Hachijo Island to the Suruga Bay via Miyake Island and Kozu Island, i.e., from off the Suruga Bay to in or near the bay. The perturbation of the sea level along the Izu Ridge occurs as waves with a period of 26 days, a wavelength of 500 km, and a phase speed of 23 cm/sec. The propagated waves and those of the Kuroshio frontal waves have the same features. This means that the periodic inflows at the eastern mouth of the Suruga Bay are caused by the passage of Kuroshio frontal waves off the bay.

Population ecology of the gulf ribbed mussel across a salinity gradient: recruitment, growth and density

USGS Publications Warehouse

Honig, Aaron; Supan, John; LaPeyre, Megan K.

2015-01-01

Benthic intertidal bivalves play an essential role in estuarine ecosystems by contributing to habitat provision, water filtration, and promoting productivity. As such, changes that impact population distributions and persistence of local bivalve populations may have large ecosystem level consequences. Recruitment, growth, mortality, population size structure and density of the gulf coast ribbed mussel, Geukensia granosissima, were examined across a salinity gradient in southeastern Louisiana. Data were collected along 100-m transects at interior and edge marsh plots located at duplicate sites in upper (salinity ~4 psu), central (salinity ~8 psu) and lower (salinity ~15 psu) Barataria Bay, Louisiana, U.S.A. Growth, mortality and recruitment were measured in established plots from April through November 2012. Mussel densities were greatest within the middle bay (salinity ~8) regardless of flooding regime, but strongly associated with highest stem densities of Juncus roemerianus vegetation. Mussel recruitment, growth, size and survival were significantly higher at mid and high salinity marsh edge sites as compared to all interior marsh and low salinity sites. The observed patterns of density, growth and mortality in Barataria Bay may reflect detrital food resource availability, host vegetation community distribution along the salinity gradient, salinity tolerance of the mussel, and reduced predation at higher salinity edge sites.

Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

USGS Publications Warehouse

Wingard, G. Lynn; Cronin, Thomas M.; Holmes, Charles W.; Willard, Debra A.; Budet, Carlos A.; Ortiz, Ruth E.

2005-01-01

Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays - the most landward bays - are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and extent of the changes needs to be determined. The preliminary information on the cores collected in 2004 will be combined with data from cores collected in July 2005. The 2005 cores were collected along transects moving from the inner bays out towards the coast. These transects, combining information from the 2004 and 2005 cores, will allow us to examine long term trends in freshwater supply, sea-level rise, and potentially the impact of storms on the coastal ecosystem.

Effects of nutrients and zooplankton on the phytoplankton community structure in Marudu Bay

NASA Astrophysics Data System (ADS)

Tan, Kar Soon; Ransangan, Julian

2017-07-01

Current study was carried out to provide a better understanding on spatial and temporal variations in the phytoplankton community structure in Marudu Bay, an important nursery ground for fishery resources within the Tun Mustapha Marine Park and Coral Triangle Initiative, and their relationship with environmental variables. Samplings were conducted monthly from April 2014 to April 2015 in Marudu Bay, Malaysia. Water samples were collected for nutrients analysis, zooplankton and phytoplankton counting. Moreover, the in situ environmental parameters were also examined. The field study showed a total of forty seven phytoplankton genera, representative of 33 families were identified. The nutrient concentrations in Marudu Bay was low (mesotrophic) throughout the year, where the phytoplankton community was often dominated by Chaetoceros spp. and Bacteriastrum spp. In general, increase in nitrate concentration triggered the bloom of centric diatom, Chaetoceros spp. and Bacteriastrum spp. in Marudu Bay. However, the bloom of these phytoplankton taxa did not occur in the presence of high ammonia concentration. In addition, high abundance of zooplankton also a limiting factor of the phytoplankton blooms particularly at end of southwest monsoon. High silica concentration promoted the growth of pennate diatoms, Proboscia spp. and Thallassionema spp., but the depletion of silica quickly terminated the bloom. Interestingly, our study showed that Chaetoceros spp., tolerated silica depletion condition, but the average cell size of this taxon reduced significantly. In summary, the phytoplankton community structure in mesotrophic environment is more sensitive to the changes in zooplankton abundance, nutrient concentration and its ratio than that in nutrient rich environments. This study also recommends that bivalve farming at industrial scale is not recommended in Marudu Bay because it potentially depletes the primary productivity hence jeopardizing the availability of live food for larvae of many natural fishery resources in the bay.

Status and trend of the Kittlitz's Murrelet Brachyramphus brevirostris in Glacier Bay, Alaska

USGS Publications Warehouse

Piatt, John F.; Arimitsu, Mayumi L.; Drew, Gary S.; Madison, Erica N.; Bodkin, James L.; Romano, Marc D.

2011-01-01

We conducted standardized surveys for marine birds in Glacier Bay in seven years between 1991 and 2008. From our most recent survey, a combination of line- and strip-transect methods completed in 2008, we estimated that 4981 (95% CI 1293–8670) Kittlitz’s Murrelets Brachyramphus brevirostris resided in Glacier Bay during the month of June, together with 12 195 (5607–18 783) Marbled Murrelets B. marmoratus. When counts were prorated to assign unidentified Brachyramphus murrelets to species, population estimates increased to 5641 Kittlitz’s Murrelets and 13 810 Marbled Murrelets. Our surveys of bird numbers in Glacier Bay between 1991 and 2008 revealed that Kittlitz’s Murrelet declined by ≥85% during this period. Trend analysis suggested a rate of decline between -10.7% and -14.4% per year. No direct human impacts (e.g., bycatch, oil pollution, vessel disturbance) in our study area could fully account for a decline of this magnitude. Widespread declines of Brachyramphus murrelets and Harbor Seals Phoca vitulina in the Gulf of Alaska during the 1980s-1990s suggest large-scale influences on these marine predators, perhaps related to climate-mediated cycles in food supply. Other natural factors that may impact Glacier Bay populations include predation by avian and terrestrial predators, widespread glacial retreat and its effect on nesting and foraging habitats, and competition for food with marine predators whose abundance in Glacier Bay has increased markedly in recent years (Humpback Whales Megaptera novaeangliae and Steller Sea Lions Eumetopias jubatus).

Worsened physical condition due to climate change contributes to the increasing hypoxia in Chesapeake Bay.

PubMed

Du, Jiabi; Shen, Jian; Park, Kyeong; Wang, Ya Ping; Yu, Xin

2018-07-15

There are increasing concerns about the impact of worsened physical condition on hypoxia in a variety of coastal systems, especially considering the influence of changing climate. In this study, an EOF analysis of the DO data for 1985-2012, a long-term numerical simulation of vertical exchange, and statistical analysis were applied to understand the underlying mechanisms for the variation of DO condition in Chesapeake Bay. Three types of analysis consistently demonstrated that both biological and physical conditions contribute equally to seasonal and interannual variations of the hypoxic condition in Chesapeake Bay. We found the physical condition (vertical exchange+temperature) determines the spatial and seasonal pattern of the hypoxia in Chesapeake Bay. The EOF analysis showed that the first mode, which was highly related to the physical forcings and correlated with the summer hypoxia volume, can be well explained by seasonal and interannual variations of physical variables and biological activities, while the second mode is significantly correlated with the estuarine circulation and river discharge. The weakened vertical exchange and increased water temperature since the 1980s demonstrated a worsened physical condition over the past few decades. Under changing climate (e.g., warming, accelerated sea-level rise, altered precipitation and wind patterns), Chesapeake Bay is likely to experience a worsened physical condition, which will amplify the negative impact of anthropogenic inputs on eutrophication and consequently require more efforts for nutrient reduction to improve the water quality condition in Chesapeake Bay. Copyright © 2018 Elsevier B.V. All rights reserved.

Pushing open-ocean organic paleo-environmental proxies to the margin: Narragansett Bay, RI

NASA Astrophysics Data System (ADS)

Salacup, J. M.; Herbert, T.; Prell, W. L.

2010-12-01

Estuarine sediment deposits provide an under-utilized opportunity to reconstruct high-resolution records of environmental change from the highly sensitive intersection of oceanic and terrestrial systems. Previous applications of both well-established and novel organic geochemical proxies to estuaries have met with mixed success. Compared to oceanic settings, the large dynamic range of tidal currents, water temperature, salinity, nutrients, and productivity both enrich and complicate estuarine sedimentary records. Here, we present the results of monthly samples of water-column particulate organic matter and compare them to a suite of sediment cores in an effort to elucidate how the environmental signal produced in the water-column is translated to the sediment. Specifically, we measured alkenones and glycerol dialkyl glycerol tetraethers (GDGTs), the bases for the Uk’37 sea-surface temperature (SST) and C-37total primary productivity proxies, and the TEX86 SST and BIT Index proxies, respectively. Alkenones, produced by haptophyte algae, are present in most of our water-column samples; however, concentrations in many samples are too low to reliably calculate temperature. When reliable, water-column alkenones infer SSTs between 13-16°C, consistent with sediment core-top Uk’37 SST estimates. These correlate to May and Oct SSTs, coinciding with the terminations of the summer-fall and winter-spring algal blooms in Narragansett Bay. In contrast to alkenone fingerprints reported from the much lower salinity Chesapeake Bay, Narragansett Bay samples lack significant contributions of the C37:4 ketone, consistent with production by open-ocean haptophytes. Notably, sedimentary records of Uk’37-inferred SST show strong inter-core centennial-to-decadal coherence. The structure and absolute values of inferred SSTs correlate well with instrumental mean Sept-Oct air temperatures back to 1895, and contain structure consistent with the late Little Ice Age and 20th century warming. Our record indicates that the past 100 in Narragansett Bay are the warmest in at least the last 500. Water-column values of the GDGT-based BIT Index, a proxy for the delivery of terrestrial organic matter (TOM), decrease down-Bay with distance from the major rivers. However, absolute values of the index, exceeding 0.8-0.9 in the upper half of the Bay, are more consistent with soil samples than water and are hard to reconcile with high level of marine productivity. Sedimentary values of the BIT Index are also high, between ~0.4 and 0.8, and their profiles suggest that Colonization (~1700) and Industrialization (~1850) altered terrestrial sediment delivery to the Bay. Such high values of the BIT Index suggest the utility of TEX86 may be complicated by terrestrial GDGT contributions. Indeed, sedimentary values for TEX86 are highly variable and show little correlation with Uk’37 or instrumental records. Our results confirm the utility of organic geochemical proxies in estuarine settings while advocating the application of more than one. In Narragansett Bay, this approach has allowed the reconstruction of local historically and climatically important events such as the impacts of European settlement, the Industrial Revolution, and 20th century warming.

Pre-impact tectonothermal evolution of the crystalline basement-derived rocks in the ICDP-USGS Eyreville B core, Chesapeake Bay impact structure

USGS Publications Warehouse

Gibson, R.L.; Townsend, G.N.; Horton, J. Wright; Reimold, W.U.

2009-01-01

Pre-impact crystalline rocks of the lowermost 215 m of the Eyreville B drill core from the Chesapeake Bay impact structure consist of a sequence of pelitic mica schists with subsidiary metagraywackes or felsic metavolcanic rocks, amphibolite, and calc-silicate rock that is intruded by muscovite (??biotite, garnet) granite and granite pegmatite. The schists are commonly graphitic and pyritic and locally contain plagioclase porphyroblasts, fi brolitic sillimanite, and garnet that indicate middle- to upper-amphibolite-facies peak metamorphic conditions estimated at ??0.4-0.5 GPa and 600-670 ??C. The schists display an intense, shallowly dipping, S1 composite shear foliation with local micrometer- to decimeter-scale recumbent folds and S-C' shear band structures that formed at high temperatures. Zones of chaotically oriented foliation, resembling breccias but showing no signs of retrogression, are developed locally and are interpreted as shear-disrupted fold hinges. Mineral textural relations in the mica schists indicate that the metamorphic peak was attained during D1. Fabric analysis indicates, however, that subhorizontal shear deformation continued during retrograde cooling, forming mylonite zones in which high-temperature shear fabrics (S-C and S-C') are overprinted by progressively lower- temperature fabrics. Cataclasites and carbonate-cemented breccias in more competent lithologies such as the calc-silicate unit and in the felsic gneiss found as boulders in the overlying impactite succession may refl ect a fi nal pulse of low-temperature cataclastic deformation during D1. These breccias and the shear and mylonitic foliations are cut by smaller, steeply inclined anastomosing fractures with chlorite and calcite infill (interpreted as D2). This D2 event was accompanied by extensive chlorite-sericitecalcite ?? epidote retrogression and appears to predate the impact event. Granite and granite pegmatite veins display local discordance to the S1 foliation, but elsewhere they are affected by high-temperature mylonitic shear deformation, suggesting a late-D1 intrusive timing close to the metamorphic peak. The D1 event is tentatively interpreted as a thrusting event associated with westward-verging collision between Gondwana and Laurentia before or during the Permian-Carboniferous Alleghanian orogeny. It is unclear whether subsequent brittle deformation, described here as D2, could be part of regional dextral Alleghanian strike-slip faulting or younger Mesozoic normal faulting. ?? 2009 The Geological Society of America.

Preparing Informal Bay Area Educators for Climate Education Success

NASA Astrophysics Data System (ADS)

Romero, M.

2016-12-01

The Bay Area Climate Literacy Impact Collaborative (Bay-CLIC) joins informal science educators from over 30 environmental education organizations with the common goal of increasing climate literacy and action. Over this past year, the collaborative has been gathering existing tools and resources that will allow informal educators in the Bay Area to communicate on climate change with confidence. Bay-CLIC's work plans to bring climate science to life by equipping educators with climate data that resonates best with local audiences, which is data that is place-based and personal. Bay-CLIC is also researching effective sustainability campaigns focused on behavior change that can be crafted to fit our unique regional context and rolled out across multiple Bay-CLIC member organizations. This session will focus on sharing our findings from our six month information gathering phase. The overarching discussion will focus on the needs that Bay Area educators identified as necessary to address in order for them to provide the best quality climate education programming. We will also discuss the data we gathered on what local educators are already using in their work and share out on how this diverse array of informal educators will be implementing our research into their programs.

Transport properties of soil particles in Sakiyamawan-Amitoriwan nature conservation area, Iriomote Island, Japan

NASA Astrophysics Data System (ADS)

Shimokawa, Shinya; Murakami, Tomokazu; Kohno, Hiroyoshi; Mizutani, Akira

2017-12-01

The actual states of soil particle transport in and exchange between the Sakiyama and Amitori bays, Iriomote Island, Japan, were investigated using atmosphere-ocean-river observations and numerical simulations. The results show that in summer in both bays large particles (≥15 μm) do not move from the vicinity of the river mouths. Small particles, however, do move to the respective east sides of the bays. In winter in both the bays, large particles move towards the center of the bays from the vicinity of the river mouths, whereas small particles move to the respective west sides of the bays. Furthermore, soil particles move mainly from the Sakiyama to the Amitori bay in summer, but this direction is reversed in winter. These features are explainable mainly by seasonal differences in wind speed and direction, but the combination among seasonal differences in wind speed and direction, the wind-driven current and the topography is also important for them. The results are useful for assessing soil particle impact on coastal marine ecosystems, such as those containing reef-building coral and Enhalus acoroides, and their effective conservation in the natural conservation areas of the Sakiyama and Amitori bays.

Characterization of organic chemical contaminants in sediments from Jobos Bay, Puerto Rico.

PubMed

Pait, Anthony S; Whitall, David R; Dieppa, Angel; Newton, Sarah E; Brune, Lia; Caldow, Chris; Mason, Andrew L; Apeti, Dennis A; Christensen, John D

2012-08-01

Jobos Bay, located on the southeastern coast of Puerto Rico, contains a variety of habitats including mangroves, seagrass meadows, and coral reefs. The watershed surrounding the bay includes a number of towns, agricultural areas, and the Jobos Bay National Estuarine Research Reserve (NERR). Jobos Bay and the surrounding watershed are part of a Conservation Effects Assessment Project (CEAP), involving the Jobos Bay NERR, the US Department of Agriculture, and the National Oceanic and Atmospheric Administration (NOAA) to assess the benefits of agricultural best management practices (BMPs) on the terrestrial and marine environments. As part of the Jobos Bay CEAP, NOAA collected sediment samples in May 2008 to characterize over 130 organic chemical contaminants. This paper presents the results of the organic contaminant analysis. The organic contaminants detected in the sediments included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and the pesticide DDT. PAHs at one site in the inner bay near a boat yard were significantly elevated; however, all organic contaminant classes measured were below NOAA sediment quality guidelines that would have indicated that impacts were likely. The results of this work provide an important baseline assessment of the marine environment that will assist in understanding the benefits of implementing BMPs on water quality in Jobos Bay.

Design, Development, and Integration of A Space Shuttle Orbiter Bay 13 Payload Carrier

NASA Technical Reports Server (NTRS)

Spencer, Susan H.; Phillips, Michael W.; Upton, Lanny (Technical Monitor)

2002-01-01

Bay 13 of the Space Shuttle Orbiter has been limited to small sidewall mounted payloads and ballast. In order to efficiently utilize this space, a concept was developed for a cross-bay cargo carrier to mount Orbital Replacement Units (ORU's) for delivery to the International Space Station and provide additional opportunities for science payloads, while meeting the Orbiter ballast requirements. The Lightweight Multi-Purpose Experiment Support Structure (MPESS) Carrie (LMC) was developed and tested by NASA's Marshall Space Flight Center and the Boeing Company. The Multi-Purpose Experiment Support Structure (MPESS), which was developed for the Spacelab program was modified, removing the keel structure and relocating the sill trunnions to fit in Bay 13. Without the keel fitting, the LMC required a new and innovative concept for transferring Y loads into the Orbiter structure. Since there is no keel fitting available in the Bay 13 location, the design had to utilize the longeron bridge T-rail to distribute the Y loads. This concept has not previously been used in designing Shuttle payloads. A concept was developed to protect for Launch-On-Need ORU's, while providing opportunities for science payloads. Categories of potential ORU's were defined, and Get-Away Special (GAS) payloads of similar mass properties were provided by NASA's Goddard Space Flight Center. Four GAS payloads were manifest as the baseline configuration, preserving the capability to swap up to two ORU's for the corresponding science payloads, after installation into the Orbiter cargo bay at the pad, prior to closeout. Multiple configurations were considered for the analytical integration, to protect for all defined combinations of ORU's and GAS payloads. The first physical integration of the LMC war performed by Goddard Space Flight Center and Kennedy Space Center at an off-line facility at Kennedy Space Center. This paper will discuss the design challenges, structural testing, analytical and physical integration for the LMC's successful maiden flight on STS-108/ISS UF-1 mission in December 2001.

Lower Flathead System Fisheries Study, South Bay of Flathead Lake, Volume III, 1983-1987 Final Report.

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

Cross, David; Waite, Ian

1988-06-01

The Lower Flathead System Fisheries Study assessed the effects of Kerr Dam operation on the fisheries of the lower Flathead ecosystem. South Bay, the southern most lobe of Flathead Lake, is the most extensive area of shallow water, and therefore, most effected by changes in lake levels. This study began in January of 1984 and was completed in early 1987. Vegetative and structural cover are relatively limited in South Bay, a condition which could contribute to lower recruitment for some fish species. Our data show that the study area contained 0.04% structural and 5.4% vegetative cover in June at fullmore » pool. Both figures are less than 1.0% at minimum pool. Structural complexity mediates the ecological interactions between littoral zone fish and their prey, and can affect local productivity and growth in fish. Structural complexity may also be important to overwinter survival of young perch in Flathead Lake. Winter conditions, including ice cover and fall drawdown, seasonally eliminate the vegetative portion of most rooted macrophytes in South Bay. This results in substantial loss of what little structural cover exists, depriving the perch population of habitat which has been occupied all summer. The loss of cover from draw-down concentrates and probably exposes perch to greater predation, including cannibalism, than would occur if structural complexity were greater. 33 refs., 10 figs., 5 tabs.« less

78 FR 57061 - Special Local Regulation; Red Bull Flugtag Miami, Biscayne Bay; Miami, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-17

.... The economic impact of this rule is not significant for the following reasons: (1) The special local... 1625-AA08 Special Local Regulation; Red Bull Flugtag Miami, Biscayne Bay; Miami, FL AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a special local regulation...

Reducing Nutrients and Nutrient Impacts Priority Issue Team - St. Louis Bay Project: Implementing Nutrients PIT Action Step 1.1

NASA Technical Reports Server (NTRS)

Mason, Ted

2011-01-01

The NASA Applied Science & Technology Project Office at Stennis Space Center(SSC) used satellites, in-situ measurements and computational modeling to study relationships between water quality in St. Louis Bay, Mississippi and the watershed characteristics of the Jourdan and Wolf rivers from 2000-2010.

76 FR 70118 - Notice of Public Meetings for the Draft Environmental Impact Statement for Basing of MV-22 and H...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-10

... and parking apron improvements; construction of additional bachelor enlisted quarters (BEQs... MCB Hawaii Kaneohe Bay, types of basing facilities that are required, improvements at training areas... construction, replacement, and renovation of facilities at MCB Hawaii Kaneohe Bay, and include improvements to...

A landscape based, systems dynamic model for assessing impacts of urban development on water quality for sustainable seagrass growth in Tampa Bay, Florida

EPA Science Inventory

We present an integrated assessment model to predict potential unintended consequences of urban development on the sustainability of seagrasses and preservation of ecosystem services, such as catchable fish, in Tampa Bay. Ecosystem services are those ecological functions and pro...

Hurricane-induced Sediment Transport and Morphological Change in Jamaica Bay, New York

NASA Astrophysics Data System (ADS)

Hu, K.; Chen, Q. J.

2016-02-01

Jamaica Bay is located in Brooklyn and Queens, New York on the western end of the south shore of the Long Island land mass. It experienced a conversion of more than 60% of the vegetated salt-marsh islands to intertidal and subtidal mudflats. Hurricanes and nor'easters are among the important driving forces that reshape coastal landscape quickly and affect wetland sustainability. Wetland protection and restoration need a better understanding of hydrodynamics and sediment transport in this area, especially under extreme weather conditions. Hurricane Sandy, which made landfall along east coast on October 30, 2012, provides a critical opportunity for studying the impacts of hurricanes on sedimentation, erosion and morphological changes in Jamaica Bay and salt marsh islands. The Delft3D model suit was applied to model hydrodynamics and sediment transport in Jamaica Bay and salt marsh islands. Three domains were set up for nesting computation. The local domain covering the bay and salt marshes has a resolution of 10 m. The wave module was online coupled with the flow module. Vegetation effects were considered as a large number of rigid cylinders by a sub-module in Delft3D. Parameters in sediment transport and morphological change were carefully chosen and calibrated. Prior- and post-Sandy Surface Elevation Table (SET)/accretion data including mark horizon (short-term) and 137Cs and 210Pb (long-term) at salt marsh islands in Jamaica Bay were used for model validation. Model results indicate that waves played an important role in hurricane-induced morphological change in Jamaica Bay and wetlands. In addition, numerical experiments were carried out to investigate the impacts of hypothetic hurricanes. This study has been supported by the U.S. Geological Survey Hurricane Sandy Disaster Recovery Act Funds.

DEVELOP Chesapeake Bay Watershed Hydrology - UAV Sensor Web

NASA Astrophysics Data System (ADS)

Holley, S. D.; Baruah, A.

2008-12-01

The Chesapeake Bay is the largest estuary in the United States, with a watershed extending through six states and the nation's capital. Urbanization and agriculture practices have led to an excess runoff of nutrients and sediment into the bay. Nutrients and sediment loading stimulate the growth of algal blooms associated with various problems including localized dissolved oxygen deficiencies, toxic algal blooms and death of marine life. The Chesapeake Bay Program, among other stakeholder organizations, contributes greatly to the restoration efforts of the Chesapeake Bay. These stakeholders contribute in many ways such as monitoring the water quality, leading clean-up projects, and actively restoring native habitats. The first stage of the DEVELOP Chesapeake Bay Coastal Management project, relating to water quality, contributed to the restoration efforts by introducing NASA satellite-based water quality data products to the stakeholders as a complement to their current monitoring methods. The second stage, to be initiated in the fall 2008 internship term, will focus on the impacts of land cover variability within the Chesapeake Bay Watershed. Multiple student led discussions with members of the Land Cover team at the Chesapeake Bay Program Office in the DEVELOP GSFC 2008 summer term uncovered the need for remote sensing data for hydrological mapping in the watershed. The Chesapeake Bay Program expressed in repeated discussions on Land Cover mapping that significant portions of upper river areas, streams, and the land directly interfacing those waters are not accurately depicted in the watershed model. Without such hydrological mapping correlated with land cover data the model will not be useful in depicting source areas of nutrient loading which has an ecological and economic impact in and around the Chesapeake Bay. The fall 2008 DEVELOP team will examine the use of UAV flown sensors in connection with in-situ and Earth Observation satellite data. To maximize the web of data, students will also examine the NASA's research into self organizing neural-networks to ensure the data is correlated in such a manner as to support the sensor web connections. Additionally, students will learn the operation and functionality of the Chesapeake Bay Program's watershed model to examine and determine the potential for integration of the sensor web data into the watershed model.

Experience of mixed-sex bays in a general hospital.

PubMed

Bryant, Debbie; Adams, John

To explore patients' and nurses' views on their experience of nursing care in mixed-sex bays. Using a descriptive exploratory method, tape-recorded semi-structured interviews were conducted with a purposive sample of patients and nurses drawn from wards where mixed-sex bays were located. The resulting transcripts were analysed to identify shared themes. The key themes identified were: communication from nursing staff, first reactions, relationships in the bay, reactions of others, awareness of organisational issues and nursing in a mixed-sex ward. While some individuals felt that the attitudes and behaviours displayed by their fellow patients were of greater significance than their gender, there was a general view that mixed-sex bays were less than ideal. Nurses also struggled to maintain patient dignity in mixed-sex bays.

Resilience of coastal wetlands to extreme hydrologicevents in Apalachicola Bay

NASA Astrophysics Data System (ADS)

Medeiros, S. C.; Singh, A.; Tahsin, S.

2017-12-01

Extreme hydrologic events such as hurricanes and droughts continuously threaten wetlands which provide key ecosystem services in coastal areas. The recovery time for vegetation after impact fromthese extreme events can be highly variable depending on the hazard type and intensity. Apalachicola Bay in Florida is home to a rich variety of saltwater and freshwater wetlands and is subject to a wide rangeof hydrologic hazards. Using spatiotemporal changes in Landsat-based empirical vegetation indices, we investigate the impact of hurricane and drought on both freshwater and saltwater wetlands from year 2000to 2015 in Apalachicola Bay. Our results indicate that saltwater wetlands are more resilient than freshwater wetlands and suggest that in response to hurricanes, the coastal wetlands took almost a year to recover,while recovery following a drought period was observed after only a month.

Resilience of coastal wetlands to extreme hydrologic events in Apalachicola Bay

NASA Astrophysics Data System (ADS)

Tahsin, Subrina; Medeiros, Stephen C.; Singh, Arvind

2016-07-01

Extreme hydrologic events such as hurricanes and droughts continuously threaten wetlands which provide key ecosystem services in coastal areas. The recovery time for vegetation after impact from these extreme events can be highly variable depending on the hazard type and intensity. Apalachicola Bay in Florida is home to a rich variety of saltwater and freshwater wetlands and is subject to a wide range of hydrologic hazards. Using spatiotemporal changes in Landsat-based empirical vegetation indices, we investigate the impact of hurricane and drought on both freshwater and saltwater wetlands from year 2000 to 2015 in Apalachicola Bay. Our results indicate that saltwater wetlands are more resilient than freshwater wetlands and suggest that in response to hurricanes, the coastal wetlands took almost a year to recover, while recovery following a drought period was observed after only a month.

Dinocyst taphonomy, impact craters, cyst ghosts, and the Paleocene-Eocene thermal maximum (PETM)

USGS Publications Warehouse

Edwards, Lucy E.

2012-01-01

Dinocysts recovered from sediments related to the Chesapeake Bay impact structure in Virginia and the earliest Eocene suboxic environment in Maryland show strange and intriguing details of preservation. Features such as curled processes, opaque debris, breakage, microborings and cyst ghosts, among others, invite speculation about catastrophic depositional processes, rapid burial and biological and chemical decay. Selected specimens from seven cores taken in the coastal plain of Virginia and Maryland show abnormal preservation features in various combinations that merit illustration, description, discussion and further study. Although the depositional environments described are extreme, many of the features discussed are known from, or could be found in, other environments. These environments will show both similarities to and differences from the extreme environments here.

Hindcasting and forecasting of climatology for Gilbert Bay, Labrador: A marine protected area

NASA Astrophysics Data System (ADS)

Best, Sara J.

Gilbert Bay is a marine protected area (MPA) on the southeastern coast of Labrador, Canada. The MPA was created to conserve a genetically distinctive population of Atlantic cod, Gadus morhua. Future climate change in the region is expected to have an impact on the coastal marine environment and local communities in the future. This thesis presents results from a hindcast and forecasts study of physical oceanographic conditions for Gilbert Bay. The first section of this thesis examines the interannual variability in atmospheric and physical oceanographic characteristics of Gilbert Bay over the period 1949-2006. The seasonal and interannual variability of the near surface atmospheric parameters are described. Seawater temperature, salinity and sea-ice thickness in winter are simulated with a physical ocean model, the General Ocean Turbulence Model (GOTM). The results of the hindcast model suggest that the atmospheric interannual variability of the Gilbert Bay region is linked to the North Atlantic Oscillation (NAO). A warming trend observed in the subpolar North Atlantic was influenced by the local climate of coastal Labrador during the recent decade of 1995-2005. The second section of this thesis presents a model forecast of the impact of climate change on the physical conditions within Gilbert Bay over the next century. Climate scenarios from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment and the US Climate Change Science Program Project (US CCSP), specifically the Special Report on Emission Scenarios (SRES), were used. Atmospheric parameters and related changes in seawater temperature, salinity and sea-ice thickness in winter for three SRES are simulated with the GOTM, and are then compared to the hindcast study results. The results suggest that the water column during future winters will become warmer in the second half of the 21st century. In the summer the atmosphere will be warmer and more humid. Cloudiness and precipitation are expected to increase. This will have an impact on the vertical stratification of the water column. The surface mixed layer is expected to become warmer, fresher and much shallower than seen in the past. The stratification below the seasonal thermocline will weaken and vertical mixing will intensify. A significant change in surface sea-ice coverage is also suggested by the forecast. Continuing reduction in sea-ice formation during the winter months as highlighted by the hindcast study is expected to affect living conditions of the neighbouring coastal communities around the bay, specifically by increasing the danger of travelling across the bay. A warming Gilbert Bay ecosystem may be favourable for cod growth, but reduced sea-ice formation during the winter months increases the danger of travelling across the bay by snowmobile.

Surface-Wave Tomographic Studies of the Hudson Bay Lithosphere: Implications for Paleoproterozoic Tectonic Processes and the Assembly of the Canadian Shield

NASA Astrophysics Data System (ADS)

Darbyshire, F. A.

2015-12-01

Hudson Bay is a shallow intracratonic basin that partially conceals the Trans-Hudson Orogen (THO) in northern Canada. The THO is thought to be a Himalayan-scale Paleoproterozoic orogenic event that was an important component of assembly of the Canadian Shield, marking the collision of the Archean Superior and Western Churchill plates. Until recently, only global and continental-scale seismic tomographic models had imaged the upper-mantle structure of the region, giving a broad but relatively low-resolution picture of the thick lithospheric keel. The Hudson Bay Lithospheric Experiment (HuBLE) investigated the present-day seismic structure beneath Hudson Bay and its surroundings, using a distributed broadband seismograph network installed around the periphery of the Bay and complemented by existing permanent and temporary seismographs further afield. This configuration, though not optimal for body-wave studies which use subvertical arrivals, is well-suited to surface wave tomographic techniques, with many paths crossing the Bay. As there is little seismicity in the region around the Canadian Shield, two-station measurements of teleseismic Rayleigh wave phase velocity formed the principal data set for lithospheric studies. The interstation measurements were combined in a linearized tomographic inversion for maps of phase velocity and azimuthal anisotropy at periods of 20-200 s; these maps were then used to calculate a pseudo-3D anisotropic upper-mantle shear-wavespeed model of the region. The model shows thick (~180-260 km), seismically fast lithosphere across the Hudson Bay region, with a near-vertical 'curtain' of lower wavespeeds trending NE-SW across the Bay, likely associated with more juvenile material trapped between the Archean Superior and Churchill continental cores during the THO. The lithosphere is layered, suggesting a 2-stage formation process. Seismic anisotropy patterns vary with depth; a circular pattern in the uppermost mantle wrapping around the Hudson Bay basin is superseded in the lower lithosphere by a pattern that mirrors THO-related structures within the crust; the lower layer thus likely formed when stress patterns related to the THO were still active.

Seagrass impact on sediment exchange between tidal flats and salt Marsh, and the sediment budget of shallow bays

USGS Publications Warehouse

Donatelli, Carmine; Ganju, Neil Kamal; Fagherazzi, Sergio; Leonardi, Nicoletta

2018-01-01

surroundings and are therefore frequently referred to as ecological engineers. The effect of seagrasses on coastal bay resilience and sediment transport dynamics is understudied. Here we use six historical maps of seagrass distribution in Barnegat Bay, USA, to investigate the role of these vegetated surfaces on the sediment storage capacity of shallow bays. Analyses are carried out by means of the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) numerical modeling framework. Results show that a decline in the extent of seagrass meadows reduces the sediment mass potentially stored within bay systems. The presence of seagrass reduces shear stress values across the entire bay, including unvegetated areas, and promotes sediment deposition on tidal flats. On the other hand, the presence of seagrasses decreases suspended sediment concentrations, which in turn reduces the delivery of sediment to marsh platforms. Results highlight the relevance of seagrasses for the long-term survival of coastal ecosystems, and the complex dynamics regulating the interaction between subtidal and intertidal landscapes.

Impact evaluation of the industrial activities in the Bay of Bakar (Adriatic Sea, Croatia): recent benthic foraminifera and heavy metals.

PubMed

Popadić, Adriana; Vidović, Jelena; Cosović, Vlasta; Medaković, Davorin; Dolenec, Matej; Felja, Igor

2013-11-15

The Bay of Bakar is one of the most heavily polluted bays at the Eastern Adriatic. Three major industrial companies potentially endanger the bay. The concentration of major, minor and trace elements in surface sediments from thirteen stations was discussed in relation to the sediment type and foraminiferal assemblages. The distribution of major elements in the bay is influenced by geological nature of surroundings. Heavy metal distribution depends on pollution sources and on amount of mud fraction: fine-grained sediments are enriched by them in comparison with coarse-grained ones. Different sediment quality criteria complicate the pollution assessment in the bay. Heavy metal concentrations generally fall into allowed depositional values for marine environments; only area in front of the coke plant and the City of Bakar harbor is heavily polluted. Stress-tolerant foraminiferal species dominate at stations with higher concentrations of heavy metals and coarse-grained sediments consist of larger number of epifaunal taxa. Copyright © 2013 Elsevier Ltd. All rights reserved.

Using Remotely Sensed Data and Watershed and Hydrodynamic Models to Evaluate the Effects of Land Cover Land Use Change on Aquatic Ecosystems in Mobile Bay, AL

NASA Technical Reports Server (NTRS)

Al-Hamdan, Mohammad Z.; Estes, Maurice G., Jr.; Judd, Chaeli; Thom, Ron; Woodruff, Dana; Ellis, Jean T.; Quattrochi, Dale; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

2012-01-01

Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land cover land use (LCLU) change in the two counties surrounding Mobile Bay (Mobile and Baldwin) on SAV stressors and controlling factors (temperature, salinity, and sediment) in the Mobile Bay estuary. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for LCLU scenarios in 1948, 1992, 2001, and 2030. Remotely sensed Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 LCLU scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the estuary. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid throughout Mobile Bay and adjacent estuaries. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to LCLU driven flow changes with the restoration potential of SAVs. Data products and results are being integrated into NOAA s EcoWatch and Gulf of Mexico Data Atlas online systems for dissemination to coastal resource managers and stakeholders.

Using Remotely Sensed Data and Watershed and Hydrodynamic Models to Evaluate the Effects of Land Cover Land Use Change on Aquatic Ecosystems in Mobile Bay, AL

NASA Astrophysics Data System (ADS)

Al-Hamdan, M. Z.; Estes, M. G.; Judd, C.; Thom, R.; Woodruff, D.; Ellis, J. T.; Quattrochi, D.; Watson, B.; Rodriguez, H.; Johnson, H.

2012-12-01

Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land cover land use (LCLU) change in the two counties surrounding Mobile Bay (Mobile and Baldwin) on SAV stressors and controlling factors (temperature, salinity, and sediment) in the Mobile Bay estuary. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for LCLU scenarios in 1948, 1992, 2001, and 2030. Remotely sensed Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 LCLU scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the estuary. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid throughout Mobile Bay and adjacent estuaries. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to LCLU driven flow changes with the restoration potential of SAVs. Data products and results are being integrated into NOAA's EcoWatch and Gulf of Mexico Data Atlas online systems for dissemination to coastal resource managers and stakeholders.

On the dynamics of the Sri Lanka Dome in the Bay of Bengal

NASA Astrophysics Data System (ADS)

Burns, Jessica M.; Subrahmanyam, Bulusu; Murty, V. S. N.

2017-09-01

East of Sri Lanka, in the northern Indian Ocean, a cold dome, known as the Sri Lanka Dome (SLD), develops during southwest monsoon season (June-September). The SLD first forms around May, matures in July, and decays around September, in association with the strong cyclonic wind stress curl. In this study, the structure and dynamics of SLD in response to the climatic events such as the Indian Ocean Dipole (IOD) are examined. Our results reveal that these climatic events modulated the subsurface temperature variability in the thermocline at ˜100 m depth, whose signature was also evident in the satellite-derived sea surface height (SSH) anomaly in the SLD region. We find that the mechanisms for the formation of SLD are consistent with previous research, and there is year-to-year variability in the SLD dynamics. This study also reveals that the atmospheric parameters including vertical wind shear and midtropospheric relative humidity are high over the SLD region and adjacent southern Bay of Bengal and show an upward (increasing) trend over the decades. This has impacted the atmospheric parameters over the northern Bay of Bengal over the decades and as a consequence the total number of monsoon depressions (June-September) decreased over the decades from 1980 to 2015, as reported by the India Meteorological Department, New Delhi. Thus, the new insight emerged from this study is the variability in the cyclogenesis and the occurrence of total number of monsoon depressions over northern Bay of Bengal over the decades is much related to the SLD dynamics.

The impact of glacier meltwater on the underwater noise field in a glacial bay

NASA Astrophysics Data System (ADS)

Glowacki, Oskar; Moskalik, Mateusz; Deane, Grant B.

2016-12-01

Ambient noise oceanography is proving to be an efficient and effective tool for the study of ice-ocean interactions in the bays of marine-terminating glaciers. However, obtaining quantitative estimates of ice melting or calving processes from ambient noise requires an understanding of how sound propagation through the bay attenuates and filters the noise spectrum. Measurements of the vertical structure in sound speed in the vicinity of the Hans Glacier in Hornsund Fjord, Spitsbergen, made with O(130) CTD casts between May and November 2015, reveal high-gradient, upward-refracting sound speed profiles created by cold, fresh meltwater during summer months. Simultaneous recordings of underwater ambient noise made at depths of 1, 10, and 20 m in combination with propagation model calculations using the model Bellhop illustrate the dominant role these surface ducts play in shaping the underwater soundscape. The surface ducts lead to a higher intensity and greater variability of acoustic energy in the near-surface layer covered by glacially modified waters relative to deeper waters, indicating deeper zones as most appropriate for interseasonal acoustic monitoring of the glacial melt. Surface waveguides in Hornsund are relatively shallow and trap sound above O(1 kHz). Deeper waveguides observed elsewhere will also trap low-frequency sounds, such as those generated by calving events for example. Finally, the ambient noise field in Hornsund is shown to be strongly dependent on the distribution of ice throughout the bay, stressing the importance of performing complementary environmental measurements when interpreting the results of acoustic surveys.

Payload bay doors and radiator panels familiarization handbook

NASA Technical Reports Server (NTRS)

Godbold, John A.

1992-01-01

The structure and mechanisms associated with the Payload Bay Doors (PLBDs) and the radiator panels are detailed. The PLBDs allow the radiator panels to be exposed to space, protect payloads from contamination, and provide an aerodynamic fairing over the payload bay. The radiator panels dissipate heat from the orbiter and regulate hydraulic fluid temperature. Contamination in the payload bay can hinder the success of missions. Therefore, the contamination control barrier which the PLBDs provide must be efficient in keeping the bay free from contaminants. The aerodynamic fairing the PLBDs provide prevents the orbiter from being torn apart by aerodynamic forces. These facts make the PLBDs and radiator panels mission critical elements of the Space Shuttle.

Analysis of the Energy Performance of the Chesapeake Bay Foundation's Philip Merrill Environmental Center

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

Griffith, B.; Deru M.; Torcellini, P.

2005-04-01

The Chesapeake Bay Foundation designed their new headquarters building to minimize its environmental impact on the already highly polluted Chesapeake Bay by incorporating numerous high-performance energy saving features into the building design. CBF then contacted NREL to perform a nonbiased energy evaluation of the building. Because their building attracted much attention in the sustainable design community, an unbiased evaluation was necessary to help designers replicate successes and identify and correct problem areas. This report focuses on NREL's monitoring and analysis of the overall energy performance of the building.

Maumee Bay State Park, Ohio. Shoreline Erosion Beach Restoration Study. Final Feasibility Report and Final Environmental Impact Statement. Interim to Western Lake Erie Shore Study. Volume 2. Appendices. Revised.

DTIC Science & Technology

1983-12-01

The vegetation is typified by a variety of vines and shrubs , including dogwood, sumac, wild plum, honeysuckle, wild grape, blackberry, honey locust...demand analysis. The SCORP studies for Ohio, Indiana , and Michigan were reviewed since most of *the Maumee Bay visitation was expected to originate...Bay State Park by State, by Zone :Distance: Zone:In Miles: Ohio Michigan : Indiana :Pennsylvania: Canada 1 : 0-25 :Lucas :Monroe :None :None :None

East Bay Marina Olympia, Thurston County, Washington. Final Detailed Project Report, Section 107, 1960 River and Harbor Act and Environmental Impact Statement

DTIC Science & Technology

1980-12-01

Int. Revue ges. Hydrobiology . Vol. 56, No. 6, pp. 947-956. 17. Pomeroy, L. R. 1959. Primary productivity of Boca Ciega Bay, Florida. Bull. Mar. Sci...4.7 feet to +18.2 feet mean lower low water (MLLW). AFFECTED ENVIRONMENT 2-6. Water Quality. Budd Inlet is a very productive area having about the...same salinity, nutrients, and turbidity as the other bays of south- ern Puget Sound. Phytoplankton production and standing crops in Budd Inlet increase

Design, fabrication, installation and flight service evaluation of a composite cargo ramp skin on a model CH-53 helicopter

NASA Technical Reports Server (NTRS)

Lowry, D. W.; Rich, M. J.

1983-01-01

The installation of a composite skin panel on the cargo ramp of a CH-530 marine helicopter is discussed. The composite material is of Kevlar/Epoxy (K/E) which replaces aluminum outer skins on the aft two bays of the ramp. The cargo ramp aft region was selected as being a helicopter airframe surface subjected to possible significant field damage and would permit an evaluation of the long term durability of the composite skin panel. A structural analysis was performed and the skin shears determined. Single lap joints of K/E riveted to aluminum were statically tested. The joint tests were used to determine bearing allowables and the required K/E skin gage. The K/E skin panels riveted to aluminum edge members were tested in a shear fixture to confirm the allowable shear and bearing strengths. Impact tests were conducted on aluminum skin panels to determine energy level and damage relationship. The K/E skin panels of various ply orientations and laminate thicknesses were then impacted at similar energy levels. The results of the analysis and tests were used to determine the required K/E skin gages in each of the end two bays of the ramp.

Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region.

PubMed

Lefcheck, Jonathan S; Orth, Robert J; Dennison, William C; Wilcox, David J; Murphy, Rebecca R; Keisman, Jennifer; Gurbisz, Cassie; Hannam, Michael; Landry, J Brooke; Moore, Kenneth A; Patrick, Christopher J; Testa, Jeremy; Weller, Donald E; Batiuk, Richard A

2018-04-03

Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.

Benthic community structure on coral reefs exposed to intensive recreational snorkeling.

PubMed

Renfro, Bobbie; Chadwick, Nanette E

2017-01-01

Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1-3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1) in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling.

Benthic community structure on coral reefs exposed to intensive recreational snorkeling

PubMed Central

Renfro, Bobbie

2017-01-01

Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1–3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1) in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling. PMID:28873449

The impact of industrial anthropization on mosquito (Diptera, Culicidae) communities in mangrove areas of Guanabara Bay (Rio de Janeiro, Brazil).

PubMed

de Souza, A S; Couri, M S; Florindo, L

2012-02-01

The effects of industrial anthropization on species composition and community diversity of Culicidae (Diptera) were studied in a mangrove area impacted by industrial activities as compared to a preserved area, both around Guanabara Bay in the state of Rio de Janeiro, Brazil. Diversity, equitability, and species richness in Culicidae community differed between the studied areas. Indicator species analysis and correspondence analysis were carried out and indicated that the Sabethini, especially Wyeomyia (Phoniomyia) theobaldi Lane, Wyeomyia (Phoniomyia) fuscipes (Edwards), and a non-identified species of Wyeomyia sp. were associated to the preserved area, whereas Aedes taeniorhynchus Wiedemann and Aedes scapularis (Rondani) to the impacted area.

Vertical Structure of Aerosols and Mineral Dust Over the Bay of Bengal From Multisatellite Observations

NASA Astrophysics Data System (ADS)

Lakshmi, N. B.; Nair, Vijayakumar S.; Suresh Babu, S.

2017-12-01

The vertical distribution of aerosol and dust extinction coefficient over the Bay of Bengal is examined using the satellite observations (Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS)) for the period from 2006 to 2017. Distinct seasonal pattern is observed in the vertical structure of both aerosol and dust over the Bay of Bengal with an enhancement of 24% in the aerosol extinction above 1 km from winter (December, January and February) to premonsoon (March, April, and May). Significant contribution of dust is observed over the northern Bay of Bengal during premonsoon season where 22% of the total aerosol extinction is contributed by dust aerosols transported from the nearby continental regions. During winter, dust transport is found to be less significant with fractional contribution of 10%-13% to the total aerosol optical depth over the Bay of Bengal. MODIS-derived dust fraction (fine mode based) shows an overestimation up to twofold compared to CALIOP dust fraction (depolarization based), whereas the Goddard Chemistry Aerosol Radiation and Transport-simulated dust fraction underestimates the satellite-derived dust fractions over the Bay of Bengal. Though the long-term variation in dust aerosol showed a decreasing trend over the Bay of Bengal, the confidence level is insufficient in establishing the robustness of the observed trend. However, significant dust-induced heating is observed above the boundary layer during premonsoon season. This dust-induced elevated heating can affect the convection over the Bay of Bengal which will have implication on the monsoon dynamics over the Indian region.

Space Shuttle UHF Communications Performance Evaluation

NASA Technical Reports Server (NTRS)

Hwu, Shian U.; Loh, Yin-Chung; Kroll, Quin D.; Sham, Catherine C.

2004-01-01

An extension boom is to be installed on the starboard side of the Space Shuttle Orbiter (SSO) payload bay for thermal tile inspection and repairing. As a result, the Space Shuttle payload bay Ultra High Frequency (UHF) antenna will be under the boom. This study is to evaluate the Space Shuttle UHF communication performance for antenna at a suitable new location. To insure the RF coverage performance at proposed new locations, the link margin between the UHF payload bay antenna and Extravehicular Activity (EVA) Astronauts at a range distance of 160 meters from the payload bay antenna was analyzed. The communication performance between Space Shuttle Orbiter and International Space Station (SSO-ISS) during rendezvous was also investigated. The multipath effects from payload bay structures surrounding the payload bay antenna were analyzed. The computer simulation tool based on the Geometrical Theory of Diffraction method (GTD) was used to compute the signal strengths. The total field strength was obtained by summing the direct fields from the antennas and the reflected and diffracted fields from the surrounding structures. The computed signal strengths were compared to the signal strength corresponding to the 0 dB link margin. Based on the results obtained in this study, RF coverage for SSO-EVA and SSO- ISS communication links was determined for the proposed payload bay antenna UHF locations. The RF radiation to the Orbiter Docking System (ODS) pyros, the payload bay avionics, and the Shuttle Remote Manipulator System (SRMS) from the new proposed UHF antenna location was also investigated to ensure the EMC/EMI compliances.

Hydrodynamic and transport responses to land reclamation in different areas of semi-enclosed subtropical bay

NASA Astrophysics Data System (ADS)

Yang, Ye; Chui, Ting Fong May

2017-07-01

Many coastal areas worldwide have been reclaimed to meet the increasing land demand. Understanding the effects of land reclamation on the hydrodynamics and transport processes of a semi-enclosed bay is therefore of significance. From a case study of Deep Bay (DB) in China and referring to idealized bay models, the effects of two types of land reclamation, one that narrows the bay mouth and another that reduces the water area inside the bay, were examined in this study. Simulation results of idealized models show that the current velocity at the bay mouth and the incoming tidal energy flux are negatively correlated with the width of bay mouth, as the tidal prism remains almost constant when the bay mouth width reduces. The bay mouth width reduction would also increase the tidal energy dissipation inside of the bay due to friction increase. In DB, a 30% reduction in the mouth width increased the bay mouth current velocity by up to 5% and the total incoming energy flux by 18%. The narrowed bay mouth also substantially changed the bay's vertical structure of salinity, increasing the stratification strength by 1.7×10-4 s-2. For reductions in the water surface area in the head of the bay, results from idealized bay simulations show that the current velocity throughout the bay, the incoming tidal energy flux, and salinity at the inner bay all decrease with water area reduction. Reclaiming 14% of area in DB, the current velocity reduced by 9% at the bay mouth, but increased in the middle and inner parts. The incoming tidal energy flux also increased as the coastline became more streamlined after reclamation, and the salinity at inner bay decreased. Both reclamation types have substantially altered the water and salt transport processes and increased the water exchange ability of the bay with the adjacent sea.

Fracture-Correlated Lineaments at Great Bay, Southeastern New Hampshire

DTIC Science & Technology

2002-01-01

U.S. Department of the Interior U.S. Geological Survey By James R. Degnan and Stewart F. Clark, Jr. Pembroke, New Hampshire 2002 In Cooperation with...Lineaments at Great Bay, Southeastern New Hampshire By James R. Degnan and Stewart F. Clark, Jr. 2 Fracture-Correlated Lineaments at Great Bay...and Mabee and others (1994). Walsh found that 24 percent of lineaments near outcrops correlate with brittle structures including joints, fracture

77 FR 63720 - Special Local Regulations; 2012 Ironman 70.3 Miami, Biscayne Bay; Miami, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-17

.... The economic impact of this rule is not significant for the following reasons: (1) The special local...-AA08 Special Local Regulations; 2012 Ironman 70.3 Miami, Biscayne Bay; Miami, FL AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a special local regulation...

77 FR 31353 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, AK

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-25

... prepared by the EPA's Region 10 (Pacific Northwest and Alaska), EPA's Office of Water, and EPA's Office of Research and Development. The EPA conducted this assessment to determine the significance of Bristol Bay's... under the Clean Water Act. The assessment is intended to provide a scientific and technical foundation...

Groundwater flow, variability, and transport pathways in the Mar Negro of the Jobos Bay National Estuarine Research Reserve, Puerto Rico

USDA-ARS?s Scientific Manuscript database

The Jobos Bay National Estuarine Research Reserve (JBNERR) is a semi-enclosed ecosystem along the southeast coast of Puerto Rico. Agriculture, including vegetable, row crop, tree fruit, pasture, and poultry, is an important land use within the watershed. To better understand the potential impact of ...

76 FR 78243 - Notice of Availability for General Conservation Plans and Notice of Intent To Prepare...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-16

... Conservation Plans (GCPs) for the Penobscot Bay, Merrymeeting Bay, and Downeast Coastal Salmon Habitat Recovery... Segment (GOM DPS) of Atlantic salmon (Salmo salar). The GCP will be implemented cooperatively by... survival and recovery of the species in the wild. The impacts of such take must also be minimized and...

76 FR 16636 - Pine Island, Matlacha Pass, Island Bay, and Caloosahatchee NWRs, Lee County, FL; Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-24

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R4-R-2010-N240; 40136-1265-0000-S3] Pine Island, Matlacha Pass, Island Bay, and Caloosahatchee NWRs, Lee County, FL; Final Comprehensive Conservation Plan and Finding of No Significant Impact for Environmental Assessment AGENCY: Fish and Wildlife...

Marine litter in submarine canyons of the Bay of Biscay

NASA Astrophysics Data System (ADS)

van den Beld, Inge M. J.; Guillaumont, Brigitte; Menot, Lénaïck; Bayle, Christophe; Arnaud-Haond, Sophie; Bourillet, Jean-François

2017-11-01

Marine litter is a matter of increasing concern worldwide, from shallow seas to the open ocean and from beaches to the deep-seafloor. Indeed, the deep sea may be the ultimate repository of a large proportion of litter in the ocean. We used footage acquired with a Remotely Operated Vehicle (ROV) and a towed camera to investigate the distribution and composition of litter in the submarine canyons of the Bay of Biscay. This bay contains many submarine canyons housing Vulnerable Marine Ecosystems (VMEs) such as scleractinian coral habitats. VMEs are considered to be important for fish and they increase the local biodiversity. The objectives of the study were to investigate and discuss: (i) litter density, (ii) the principal sources of litter, (iii) the influence of environmental factors on the distribution of litter, and (iv) the impact of litter on benthic communities. Litter was found in all 15 canyons and at three sites on the edge of the continental shelf/canyon, in 25 of 29 dives. The Belle-île and Arcachon Canyons contained the largest amounts of litter, up to 12.6 and 9.5 items per 100 images respectively. Plastic items were the most abundant (42%), followed by fishing-related items (16%). The litter had both a maritime and a terrestrial origin. The main sources could be linked to fishing activities, major shipping lanes and river discharges. Litter appeared to accumulate at water depths of 801-1100 m and 1401-1700 m. In the deeper of these two depth ranges, litter accumulated on a geologically structured area, accounting for its high frequency at this depth. A larger number of images taken in areas of coral in the shallower of these two depth ranges may account for the high frequency of litter detection at this depth. A larger number of litter items, including plastic objects in particular, were observed on geological structures and in coral areas than on areas of bare substratum. The distribution of fishing-related items was similar for the various types of relief. Litter items were mostly colonised by scleractinian corals and hydroids. Several fish species and a lithodid crab seemed to associate with the accumulated litter. This extensive study showed litter to be widely distributed in the submarine canyons of the Bay of Biscay. These findings increase our understanding of the distribution of litter, its composition and accumulation and its impact on benthic communities.

Chromogenic assay for BAY 81-8973 potency assignment has no impact on clinical outcome or monitoring in patient samples.

PubMed

Kitchen, S; Katterle, Y; Beckmann, H; Maas Enriquez, M

2016-06-01

Essentials Discrepancies can exist in factor VIII activity measured by the one-stage or chromogenic assays. LEOPOLD trial data were used to assess clinical impact of BAY 81-8973 potency assignment assay. Efficacy was not affected by the assay used for potency assignment and dosing of BAY 81-8973. Either assay may be used to measure factor VIII activity after BAY 81-8973 infusion. Background Product-specific discrepancies have been reported for factor VIII (FVIII) activity determined with one-stage or chromogenic assays. Objective To assess the clinical impact of potency assignment of BAY 81-8973, a full-length, unmodified, recombinant human FVIII, by use of the chromogenic assay or chromogenic assay adjusted to mimic results obtained with the one-stage assay Patients/methods Patients aged 12-65 years with severe hemophilia A received BAY 81-8973 in LEOPOLD I (20-50 IU kg(-1) two or three times weekly [investigator decision]) and LEOPOLD II (randomized to 20-30 IU kg(-1) twice weekly, 30-40 IU kg(-1) three times weekly, or on-demand treatment). Both trials included two 6-month crossover periods in which potency labeling was determined with the chromogenic substrate assay as per the European Pharmacopoeia (CS/EP) or the chromogenic substrate assay adjusted to mimic results obtained with the one-stage assay (CS/ADJ). The annualized bleeding rate (ABR) and FVIII incremental recovery were assessed by the use of pooled data. Results The analysis was perfomed on 121 patients. Median (quartile [Q] 1; Q3) ABRs during the CS/EP and CS/ADJ periods were 1.98 (0; 5.92) and 1.98 (0; 7.34), respectively. The mean incremental recovery was > 2 IU dL(-1) per IU kg(-1) in both periods with the use of either assay for postinfusion FVIII measurements. The median (Q1; Q3) chromogenic/one-stage assay recovery ratio was 1.054 (0.892; 1.150) for the CS/EP period when a plasma standard was used for calibration. Conclusions No impact on the ABR was observed with chromogenic-based as compared with one-stage assay-based potency and dosing. Either assay may be used to determine FVIII plasma activity after infusion of BAY 81-8973 without the need for a product-specific standard. © 2016 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.

The Impact of Water Loading on Estimates of Postglacial Decay Times in Hudson Bay

NASA Astrophysics Data System (ADS)

Han, H. K.; Gomez, N. A.

2016-12-01

Ongoing glacial isostatic adjustment (GIA) due to surface loading (ice and water) variations since the Last Glacial Maximum (LGM) has been contributing to sea level changes globally throughout the Holocene, especially in regions like the Canada that were heavily glaciated during the LGM. The spatial and temporal distribution of GIA and relative sea level change are attributed to the ice history and the rheological structure of the solid Earth, both of which are uncertain. It has been shown that relative sea level curves in previously glaciated regions follow an exponential-like form, and the post glacial decay times associated with that form have weak sensitivity to the details of the ice loading history (Andrews 1970, Walcott 1980, Mitrovica & Peltier 1995). Post glacial decay time estimates may therefore be used to constrain the Earth's structure and improve GIA predictions. However, estimates of decay times in Hudson Bay in the literature differ significantly due to a number of sources of uncertainty and bias (Mitrovica et al. 2000). Previous decay time analyses have not considered the potential bias that surface loading associated with Holocene sea level changes can introduce in decay time estimates derived from nearby relative sea level observations. We explore the spatial patterns of post glacial decay time predictions in previously glaciated regions, and their sensitivity to ice and water loading history. We compute post glacial sea level changes over the last deglaciation from 21ka to the modern associated with the ICE5G (Peltier, 2004) and ICE6G (Argus et al. 2014, Peltier et al. 2015) ice history models. We fit exponential curves to the modeled relative sea level changes, and compute maps of post glacial decay time predictions across North America and the Arctic. In addition, we decompose the modeled relative sea level changes into contributions from water and ice loading effects, and compute the impact of water loading redistribution since the LGM on present day decay times. We show that Holocene water loading in the Hudson Bay may introduce significant bias in decay time estimates and we highlight locations where biases are minimized.

The Chesapeake Bay Impact Crater: An Educational Investigation for Students into the Planetary Impact Process and its Environmental Consequences

NASA Technical Reports Server (NTRS)

Levine, Arlene S.

2008-01-01

Planetary impact craters are a common surface feature of many planetary bodies, including the Earth, the Moon, Mars, Mercury, Venus, and Jupiter s moons, Ganymede and Callisto. The NASA Langley Research Center in Hampton, VA, is located about 5 km inside the outer rim of the Chesapeake Bay Impact Crater. The Chesapeake Bay Impact Crater, with a diameter of 85 km is the sixth largest impact crater on our planet. The U.S. Geological Survey (USGS), in collaboration with the NASA Langley Research Center, the Virginia Department of Environmental Quality (VDEQ), the Hampton Roads Planning District Commission (HRPDC), and the Department of Geology of the College of William and Mary (WM) drilled into and through the crater at the NASA Langley Research Center and obtained a continuous core to a depth of 2075.9 ft (632.73 meters) from the Chesapeake Bay Impact Crater. At the NASA Langley location, the granite basement depth was at 2046 ft (623.87 meters). This collaborative drilling activity provided a unique educational opportunity and ongoing educational partnership between USGS, NASA Langley and the other collaborators. NASA Langley has a decade-long, ongoing educational partnership with the Colonial Coast Council of the Girl Scouts. The core drilling and on site analysis and cataloguing of the core segments provided a unique opportunity for the Girl Scouts to learn how geologists work in the field, their tools for scientific investigation and evaluation, how they perform geological analyses of the cores in an on-site tent and learn about the formation of impact craters and the impact of impacting bodies on the sub-surface, the surface, the oceans and atmosphere of the target body. This was accomplished with a two-part activity. Girl Scout day camps and local Girl Scout troops were invited to Langley Research Center Conference Center, where more than 300 Girl Scouts, their leaders and adult personnel were given briefings by scientists and educators from the USGS, NASA, VDEQ, HRPDC and WM on the principles of geology, the formation of impact craters, the consequences of the impacting body on the atmosphere, ocean, surface and sub-surface, the geological, chemical and biological analyses of the core and the cataloguing and storage of the core segments, etc. After the briefings, the Girl Scouts visited the drilling site where they inspected the core drilling rig, examined the core samples and discussed the drilling procedures, cores and interpretation of the cores with scientists and educators from the organizations conducting the core drilling. Demonstrations at the drilling site included demonstrations of impacting objects hitting multi-colored layered mud targets at different angles of entry. The multi-colored layers of mud were instructive in mapping out the distribution of impact-ejected material around the impact crater. The presentation will include a series of photographs of the Girl Scout participating in activities at the Chesapeake Bay Impact Crater drill site, including retrieving cores from the drilling rig, inspecting the core samples and participating in the impact-crater formation demonstrations.

Hindcasting of Storm Surges, Currents, and Waves at Lower Delaware Bay during Hurricane Isabel

NASA Astrophysics Data System (ADS)

Salehi, M.

2017-12-01

Hurricanes are a major threat to coastal communities and infrastructures including nuclear power plants located in low-lying coastal zones. In response, their sensitive elements should be protected by smart design to withstand against drastic impact of such natural phenomena. Accurate and reliable estimate of hurricane attributes is the first step to that effort. Numerical models have extensively grown over the past few years and are effective tools in modeling large scale natural events such as hurricane. The impact of low probability hurricanes on the lower Delaware Bay is investigated using dynamically coupled meteorological, hydrodynamic, and wave components of Delft3D software. Efforts are made to significantly reduce the computational overburden of performing such analysis for the industry, yet keeping the same level of accuracy at the area of study (AOS). The model is comprised of overall and nested domains. The overall model domain includes portion of Atlantic Ocean, Delaware, and Chesapeake bays. The nested model domain includes Delaware Bay, its floodplain, and portion of the continental shelf. This study is portion of a larger modeling effort to study the impact of low probability hurricanes on sensitive infrastructures located at the coastal zones prone to hurricane activity. The AOS is located on the east bank of Delaware Bay almost 16 miles upstream of its mouth. Model generated wind speed, significant wave height, water surface elevation, and current are calibrated for hurricane Isabel (2003). The model calibration results agreed reasonably well with field observations. Furthermore, sensitivity of surge and wave responses to various hurricane parameters was tested. In line with findings from other researchers, accuracy of wind field played a major role in hindcasting the hurricane attributes.

Support for EU fundraising in the field of Environment & Energy - BayFOR

NASA Astrophysics Data System (ADS)

Ammerl, Thomas; Baumann, Cornelia; Reiter, Andrea; Blume, Andreas; Just, Jana; Franke, Jan

2013-04-01

The Bavarian Research Alliance (BayFOR, http://www.bayfor.org) is a private company for the support of Bavaria (Free State in the South East of Germany) as a centre for science and innovation within the European Research Area. It was set up on the initiative of the Bavarian universities to strengthen their networking at regional, national and international level while helping them to prepare to meet the requirements for European research funding. The focus is directed at the current EU Framework Programme (FP7) and the forthcoming Framework Programme for Research and Innovation "Horizon 2020", but also comprises the wide range of European programmes (e.g. FP7, LIFE+, Interreg, COST, EUREKA, ERA-Nets, IEE (CIP), LLP, Calls for tender). BayFOR is also a partner institution in the Bavarian "Haus der Forschung" (www.hausderforschung.bayern.de/en). BayFORs overall aim is to strengthen and permanently anchor the science and innovation location of Bavaria in the European Research Area through: a) Initiation of national and in particular European innovation and science partnerships from academia and business b) Improvement of innovation potential of Bavarian universities and SME c) Support in acquisition, management and dissemination of results of European and international projects in the field of research and technological development The service portfolio of the EU Funding Advisory Service reaches from the first project idea to project implementation. The minimum condition for BayFOR support is at least one partner from Bavaria (Germany) must be part of the applying consortium: a) Recommendation of funding programmes/instruments (incl. integration of relevant EU policies & directives) b) Partner search c) Project development and proposal elaboration (Online platform, Creation of consortium, Attendance at meetings, Preparation of documents, Proposal structure elaboration, Provision of templates, Editorial support: Gantt, PERT, Impact, EU added value) d) Support in the Contract negotiations with the European Commission e) Project implementation (Project management, dissemination, Science-Policy-Interface) BayFOR staff has profound R&D background, as well as knowledge and experience in disseminating project outcomes, in particular with regard to the adaptation of results to the needs of relevant target groups like science, industry/SMEs, policy makers and the public. Furthermore, BayFOR can draw on distinct experience in the management of European research projects (e.g. CLIMB, Largecells, AlpBC, GeoMol, WE-EEN, WINALP). As a partner in the network for SMEs "Enterprise Europe Network" (EEN), BayFOR offers advice and support on topics such as funding, research programs, public procurement, market penetration and the promotion of innovation at European level. Beyond, BayFOR will make use of its regional networks to promote uptake and exploitation of project results. BayFOR is also commissioned by Bavaria's State Ministry of Science, Research and the Arts to look after the Bavarian University Funding Programme for the Initiation of International Projects (BayIntAn). Our efforts are aimed at initiating or strengthening transnational collaborative research involving Bavarian universities and universities of applied sciences.

The Chesapeake Bay Crater: Geology and geophysics of a Late Eocene submarine impact structure

USGS Publications Warehouse

Poag, C. Wylie; Koeberl, Christian; Reimold, Wolf Uwe

2004-01-01

The list of impact craters documented on Earth is short. Only about 165 genuine impact structures have been identified to date (Table 1.1). Even so, the number is steadily increasing at the rate of ∼3–5 per year (Grieve et al. 1995; Earth Impact Database at http://www.unb.ca/passc/Impact/Database/). In stark contrast, most other rocky planets and satellites of our solar system are pockmarked by thousands to hundreds of thousands of impact features (Beatty et al. 1999). Nevertheless, impact specialists acknowledge that Earth, too, has undergone billions of years of bolide bombardment (Melosh 1989; Schoenberg et al. 2002). The most intense bombardment, however, took place during Earth’s earliest history (∼3.8–4 Ga; Ryder 1990; Cohen et al. 2000; Ryder et al. 2000). Traces of most terrestrial impacts have been completely erased or strongly altered by the dynamic processes of a thick atmosphere, deep ocean, and mobile crust, a combination unique to our planet. Planetary geologists now recognize that processes associated with bolide impacts are fundamental to planetary accretion and surface modification (Melosh 1989; Peucker-Ehrenbrink and Schmitz 2001). Incoming meteorites may have been primary sources for Earth’s water, and, perhaps, even organic life as we know it (Thomas et al. 1997; Kring 2000). There is little doubt that impacts played a major role in the evolution of Earth’s biota (Ryder et al. 1996; Hart 1996).

Maps showing textural characteristics of benthic sediments in the Corpus Christi Bay estuarine system, south Texas

USGS Publications Warehouse

Shideler, Gerald L.; Stelting, Charles E.; McGowen, Joseph H.

1981-01-01

Corpus Christi Bay is a heavily used estuary on the south Texas coast in the northwest Gulf of Mexico (fig. 1).  The Bay is stressed by diverse activities which could substantially affect its ecosystem.  Such activities include shipping, resource production (oil, gas, and construction aggregate), commercial and sport fishing, and recreation.  Shipping activities alone have had a substantial impact on the bay.  For example, the past maintenance of navigation channels has required extensive dredging and spoil disposal within the estuarine system.  Numerous subaqueous spoil disposal sites and subaerial spoil banks are present throughout the bay (fig. 1), and the selection of future spoil disposal sites is becoming a critical local problem.  As activities in the bay increase, the need for effective environmental management becomes increasingly important, and effective management necessitates a good understanding of the bay's physical characteristics.  The objective of this study is to provide detailed information about the textural composition of bottom sediments within the estuarine system, information which could be used in making environmental-management decisions.  Visual descriptions of bottom sediments in Corpus Christi Bay and adjacent areas have been presented by McGowen and Morton (1979).  Additionally, a study of the textures of sediments on the Inner Continental Shelf adjacent to the bay has been presented by Shideler and Berryhill (1977).

Tampa Bay Integrated Science Pilot Study: Baseline mapping, land surface dynamics and predictive modeling, and hazards vulnerability studies

USGS Publications Warehouse

Crane, Michael; Yates, Kimberly; Clark, Robert; Gesch, Dean; Hess, Kurt; Koehmstedt, John; Milbert, Dennis; Parker, Bruce; Sechrist, Dan; Tilley, Janet; Wilson, Robert

2001-01-01

Tampa Bay and its environs have experienced phenomenal urban growth and significant changes in land cover and land-use practices over the past 50 years. This trend is expected to continue, with the impact of human activity broadening geographically and intensifying throughout the region.One of the immediate impacts of urban growth is the creation of additional impervious surfaces, which in turn, generate increased urban runoff that contributes to higher levels of nutrient loading in water bodies throughout the area.To better understand these and other anthropogenic affects on the ecology of the natural environment of the region, this component of the Tampa Bay Pilot Study took a broad basin-wide view. This regional view was intended to provide geographic and temporal context for the smaller intensely studied sample field site locations within the estuarine environment.

Potential Threat of Microplastics to Zooplanktivores in the Surface Waters of the Southern Sea of Korea.

PubMed

Kang, Jung-Hoon; Kwon, Oh-Youn; Shim, Won Joon

2015-10-01

The potential impact of microplastic to zooplanktivores was assessed by measuring a ratio of neustonic microplastics to zooplankton by abundance in the southern sea of Korea. Neustonic microplastics and zooplankton (0.33-2 mm) were collected using a 330-μm mesh Manta trawl in Geoje eastern Bay and Jinhae Bay before and after the rainy season in 2012 and 2013. The mean microplastic to zooplankton ratios were 0.086 (May) and 0.022 (July) in 2012, and 0.016 (June) and 0.004 (July) in 2013, indicating that zooplanktivores could be more likely to feed on microplastics than natural preys before the rainy season in 2012 and 2013. In particular, the relatively high ratio occurred in a semi-enclosed bay characterized by a shipyard and a beach resort in Geoje Bay, and at stations close to a wastewater treatment plant and an aquaculture facility in Jinhae Bay before the rainy season. Among dominant microplastics and zooplankton before the rainy season, meroplankton of macrobenthos could be confused with paint particles in Geoje Bay, 2012, whereas Styrofoam could be mistaken as immature copepods by predators in Jinhae Bay, 2013. These observations suggest that zooplanktivores could be more likely to feed on microplastics than natural preys around Geoje and Jinhae Bays before the rainy season.

KSC-2014-3264

NASA Image and Video Library

2014-07-23

CAPE CANAVERAL, Fla. – Steel structures surround High Bay 3 inside the Vehicle Assembly Building, or VAB, at NASA’s Kennedy Space Center in Florida. In view, high above, is the 175-ton crane. Banners note the heights of the Saturn V, Space Launch System, or SLS, and shuttle on the steel structure. Modifications are underway in the VAB to prepare High Bay 3 for a new platform system. The modifications are part of a centerwide refurbishment initiative under the Ground Systems Development and Operations Program. High bay 3 is being refurbished to accommodate NASA’s Space Launch System and a variety of other spacecraft. For more information, visit http://www.nasa.gov/exploration/systems/ground/index.html. Photo credit: NASA/Dimitri Gerondidakis

Seasonal variations in the community structures of macrobenthic fauna and their health status in an estuarine bay, Gwangyang Bay in Korea

NASA Astrophysics Data System (ADS)

Seo, Jin-Young; An, Soon-Mo; Lim, Dhong-il; Choi, Jin-Woo

2017-09-01

Macrobenthic fauna in an estuarine Gwangyang Bay, southern Korean coast, were investigated to uncover recent variations in their community structures. In the study area, macrobenthic faunal communities were mainly composed of polychaete worms which were the most abundant faunal group with the highest values in species number and density, while mollusks accounted for the highest proportion in total biomass. There was no clear seasonal difference in species richness during the two year period of the investigation, but the mean density and biomass increased every spring and summer due to the mass recruitment of Theora fragilis. The Shannon's diversity index (H') was more than 2.0 during most sampling seasons and did not show any significant seasonal difference except for the data in August, 2011 when azoic conditions occurred. The community structures of macrobenthos in Gwangyang Bay did not show any remarkable change in the dominance of the two top dominant species, Scoletoma longifolia and Heteromastus filiformis, which abundantly occurred in all seasons, except for the abundance peaks associated with high occurrence of T. fragilis and Paraprionospio cordifolia, especially in spring and summer and in autumn, respectively. These fauna changes reflected the changes in the macrobenthic community health status in Gwangyang Bay, where stable conditions and a healthy status prevailed in winter, but a slightly disturbed status prevailed from spring to autumn.

Glider Observations of Upper Ocean Structure in the Bay of Bengal

DTIC Science & Technology

2015-09-30

1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Glider Observations of Upper Ocean Structure in the Bay...using gliders and floats • Improve glider technology to overcome fresh, buoyant surface layers • Establish a new technology to observe turbulence...with profiling floats APPROACH We use two approaches to observe the upper ocean in the BoB. First, we deploy Spray underwater gliders to resolve

[Behavioral and acoustical characteristics of the reproductive gathering of beluga whales (Delphinapterus leucas) in the vicinity of Myagostrov, Golyi Sosnovets, and Roganka Islands (Onega Bay, the White Sea)].

PubMed

Alekseeva, Ia I; Panova, E M; Bel'kovich, V M

2013-01-01

The structure of the summer reproductive gathering of beluga whales Delphinapterus leucas was studied in the vicinity of Myagostrov, Golyi Sosnovets, and Roganka islands (Onega Bay, the White Sea) in 2006 and 2008. The abundance, age and sex structure, behavior, and swimming and acoustic behavior were studied in detail.

Effect of long-term mechanical perturbation on intertidal soft-bottom meiofaunal community spatial structure

NASA Astrophysics Data System (ADS)

Boldina, Inna; Beninger, Peter G.; Le Coz, Maïwen

2014-01-01

Situated at the interface of the microbial and macrofaunal compartments, soft-bottom meiofauna accomplish important ecological functions. However, little is known of their spatial distribution in the benthic environment. To assess the effects of long-term mechanical disturbance on soft-bottom meiofaunal spatial distribution, we compared a site subjected to long-term clam digging to a nearby site untouched by such activities, in Bourgneuf Bay, on the Atlantic coast of France. Six patterned replicate samples were taken at 3, 6, 9, 12, 15, 18, 21 and 24 cm lags, all sampling stations being separated by 5 m. A combined correlogram-variogram approach was used to enhance interpretation of the meiofaunal spatial distribution; in particular, the definition of autocorrelation strength and its statistical significance, as well as the detailed characteristics of the periodic spatial structure of nematode assemblages, and the determination of the maximum distance of their spatial autocorrelation. At both sites, nematodes and copepods clearly exhibited aggregated spatial structure at the meso scale; this structure was attenuated at the impacted site. The nematode spatial distribution showed periodicity at the non-impacted site, but not at the impacted site. This is the first explicit report of a periodic process in meiofaunal spatial distribution. No such cyclic spatial process was observed for the more motile copepods at either site. This first study to indicate the impacts of long-term anthropogenic mechanical perturbation on meiofaunal spatial structure opens the door to a new dimension of mudflat ecology. Since macrofaunal predator search behaviour is known to be strongly influenced by prey spatial structure, the alteration of this structure may have important consequences for ecosystem functioning.

Microbial Community Structure in Relation to Water Quality in ...

EPA Pesticide Factsheets

Weeks Bay is a shallow, microtidal, eutrophic sub-estuary of Mobile Bay, AL. High watershed nutrient inputs to the estuary contribute to a eutrophic condition characterized by frequent summertime diel-cycling hypoxia and dissolved oxygen (DO) oversaturation. Spatial and seasonal variability of microbial communities that contribute to estuarine ecosystem metabolism were characterized using high-throughput DNA sequencing. Surface water samples were collected from spring to fall at three sites along a transect of Weeks Bay from the Fish River to Mobile Bay. Water samples were analyzed for physiochemical properties and were also filtered onto Sterivex filters for DNA extraction. Genes for 16S rRNA and 18S rRNA were amplified and sequenced according to Earth Microbiome Project protocols. Sequences were assembled into contigs and clustered into OTUs with mothur using the Silva database. The prokaryotes were dominated by Cyanobacteria, Actinobacteria, and Spartobacteria, whereas the eukaryotes were dominated by Bacillariophyta (diatoms). Multivariate statistical analysis of microbial community composition and environmental data showed that Bacteria, Archaea and Eukaryota were clustered by season. BEST analysis by station showed that prokaryotic community structure was associated with salinity and CDOM (Rho=0.924), whereas eukaryotic community structure was most associated with salinity (Rho=0.846). Prokaryotic community structure within seasons was associated with six

Impacts of diverted freshwater on dissolved organic matter and microbial communities in Barataria Bay, Louisiana, U.S.A.

PubMed

Bianchi, Thomas S; Cook, Robert L; Perdue, E Michael; Kolic, Paulina E; Green, Nelson; Zhang, Yaoling; Smith, Richard W; Kolker, Alexander S; Ameen, Alex; King, Gary; Ojwang, Loice M; Schneider, Caroline L; Normand, Anna E; Hetland, Robert

2011-12-01

Here we present results of an initial assessment of the impacts of a water diversion event on the concentrations and chemical composition of dissolved organic matter (DOM) and bacterioplankton community composition in Barataria Bay, Louisiana U.S.A, an important estuary within the Mississippi River Delta complex. Concentrations and spectral properties of DOM, as reflected by UV/visible absorbance and fluorescence, were strikingly similar at 26 sites sampled along transects near two western and two eastern areas of Barataria Bay in July and September 2010. In September 2010, dissolved organic carbon (DOC) was significantly higher (568.1-1043 μM C, x=755.6+/-117.7 μM C, n=14) than in July 2010 (249.1-577.1 μM C, x=383.7+/-98.31 μM C, n=14); conversely, Abs254 was consistently higher at every site in July (0.105-0.314) than in September (0.080-0.221), averaging 0.24±0.06 in July and 0.15±0.04 in September. Fluorescence data via the fluorescence index (FI450/500) revealed that only 30% (8 of 26) of the July samples had an FI450/500 above 1.36, compared to 96% (25 of 26) for the September samples. This indicates a more terrestrial origin for the July DOM. Bacterioplankton from eastern sites differed in composition from bacterioplankon in western sites in July. These differences appeared to result from reduced salinities caused by the freshwater diversion. Bacterioplankton communities in September differed from those in July, but no spatial structure was observed. Thus, the trends in bacterioplankton and DOM were likely due to changes in water masses (e.g., input of Mississippi River water in July and a return to estuarine waters in September). Discharge of water from the Davis Pond Freshwater Diversion (DPFD) through Barataria Bay may have partially mitigated some adverse effects of the oil spill, inasmuch as DOM is concerned. Copyright © 2011 Elsevier Ltd. All rights reserved.

Geomorphic change in Dingzi Bay, East China since the 1950s: impacts of human activity and fluvial input

NASA Astrophysics Data System (ADS)

Tian, Qing; Wang, Qing; Liu, Yalong

2017-06-01

This study examines the geomorphic evolution of Dingzi Bay, East China in response to human activity and variations in fluvial input since the 1950s. The analysis is based on data from multiple mathematical methods, along with information obtained from Remote Sensing, Geographic Information System and Global Position System technology. The results show that the annual runoff and sediment load discharged into Dingzi Bay display significant decreasing trends overall, and marked downward steps were observed in 1966 and 1980. Around 60%-80% of the decline is attributed to decreasing precipitation in the Wulong River Basin. The landform types in Dingzi Bay have changed significantly since the 1950s, especially over the period between 1981 and 1995. Large areas of tidal flats, swamp, salt fields, and paddy fields have been reclaimed, and aquaculture ponds have been constructed. Consequently, the patterns of erosion and deposition in the bay have changed substantially. Despite a reduction in sediment input of 65.68% after 1966, low rates of sediment deposition continued in the bay. However, deposition rates changed significantly after 1981 owing to large-scale development in the bay, with a net depositional area approximately 10 times larger than that during 1961-1981. This geomorphic evolution stabilized following the termination of large-scale human activity in the bay after 1995. Overall, Dingzi Bay has shown a tendency towards silting-up during 1952-2010, with the bay head migrating seaward, the number of channels in the tidal creek system decreasing, and the tidal inlet becoming narrower and shorter. In conclusion, largescale development and human activity in Dingzi Bay have controlled the geomorphic evolution of the bay since the 1950s.

Bay breeze climatology at two sites along the Chesapeake bay from 1986-2010: Implications for surface ozone.

PubMed

Stauffer, Ryan M; Thompson, Anne M

Hourly surface meteorological measurements were coupled with surface ozone (O 3 ) mixing ratio measurements at Hampton, Virginia and Baltimore, Maryland, two sites along the Chesapeake Bay in the Mid-Atlantic United States, to examine the behavior of surface O 3 during bay breeze events and quantify the impact of the bay breeze on local O 3 pollution. Analyses were performed for the months of May through September for the years 1986 to 2010. The years were split into three groups to account for increasingly stringent environmental regulations that reduced regional emissions of nitrogen oxides (NO x ): 1986-1994, 1995-2002, and 2003-2010. Each day in the 25-year record was marked either as a bay breeze day, a non-bay breeze day, or a rainy/cloudy day based on the meteorological data. Mean eight hour (8-h) averaged surface O 3 values during bay breeze events were 3 to 5 parts per billion by volume (ppbv) higher at Hampton and Baltimore than on non-bay breeze days in all year periods. Anomalies from mean surface O 3 were highest in the afternoon at both sites during bay breeze days in the 2003-2010 study period. In conjunction with an overall lowering of baseline O 3 after the 1995-2002 period, the percentage of total exceedances of the Environmental Protection Agency (EPA) 75 ppbv 8-h O 3 standard that occurred on bay breeze days increased at Hampton for 2003-2010, while remaining steady at Baltimore. These results suggest that bay breeze circulations are becoming more important to causing exceedance events at particular sites in the region, and support the hypothesis of Martins et al. (2012) that highly localized meteorology increasingly drives air quality events at Hampton.

Establishment of the green mussel, Perna viridis (Linnaeus 1758) (Mollusca: Mytilidae) on the West Coast of Florida

USGS Publications Warehouse

Benson, A.J.; Marelli, D.C.; Frischer, M.E.; Danforth, J.M.; Williams, J.D.

2001-01-01

In 1999, the green mussel, Perna viridis, was first observed in Tampa Bay, Florida. This was the first reported occurrence of this Indo-Pacific marine bivalve in North America. The mussels found in Tampa Bay were confirmed to be P. viridis based on both morphological and genetic characteristics. Since the initial discovery, surveys in Tampa Bay and on the west coast of Florida have documented the growth, recruitment, and range expansion of P. viridis. From November 1999 to July 2000, the mean shell length of a Tampa Bay population increased from 49.0 mm to 94.1 mm, an increase of 97%. Populations of P. viridis are successfully reproducing in Tampa Bay. Recruitment was observed on sampling plates in May and continued through July 2000. The full extent of mussel colonization is not clear, but mussels were found outside Tampa Bay in St. Petersburg, Florida, south to Venice. Based on these studies it is evident that P. viridis has successfully invaded Tampa Bay and the west coast of Florida. The long-term impact of P. viridis on native communities off the west coast of Florida cannot be predicted at this time.

Closeup view of the payload bay side of the aft ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the payload bay side of the aft crew compartment bulkhead of the Orbiter Discovery. Showing the airlock, the beam-truss attach structure supporting it and its attach points to the payload bay sill longerons. This photograph was taken in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Mitigation of Shore Damage Attributed to the Federal Navigation Structures at Hammond Bay Harbor.

DTIC Science & Technology

1976-11-01

34.’,u:e bz ma :’s Winter wren :,. UsatN2II Golden crown kinglet , f, cI’OPuM Cedar waxwing ’ ’’w .": x?,r’ ,7jq Northern shrike * , ~ PIPar Starling...flycatcher Pct-,hlidon Bank swallows Progue sabis Purple martins Troo Zodytes aedon House wren Dv,,’tolZa oaroliensis Catbird T ,xosterna rufern Brown...and Related Land Resources b the Wic ’ , sir ,S ,ounci 1. S. ai 9.t Mr. and Mi_rs. Joseph__ Mser I. Comment: We have read the environin.ntaIl impact

Novel Mps1 Kinase Inhibitors with Potent Antitumor Activity.

PubMed

Wengner, Antje M; Siemeister, Gerhard; Koppitz, Marcus; Schulze, Volker; Kosemund, Dirk; Klar, Ulrich; Stoeckigt, Detlef; Neuhaus, Roland; Lienau, Philip; Bader, Benjamin; Prechtl, Stefan; Raschke, Marian; Frisk, Anna-Lena; von Ahsen, Oliver; Michels, Martin; Kreft, Bertolt; von Nussbaum, Franz; Brands, Michael; Mumberg, Dominik; Ziegelbauer, Karl

2016-04-01

Monopolar spindle 1 (Mps1) has been shown to function as the key kinase that activates the spindle assembly checkpoint (SAC) to secure proper distribution of chromosomes to daughter cells. Here, we report the structure and functional characterization of two novel selective Mps1 inhibitors, BAY 1161909 and BAY 1217389, derived from structurally distinct chemical classes. BAY 1161909 and BAY 1217389 inhibited Mps1 kinase activity with IC50 values below 10 nmol/L while showing an excellent selectivity profile. In cellular mechanistic assays, both Mps1 inhibitors abrogated nocodazole-induced SAC activity and induced premature exit from mitosis ("mitotic breakthrough"), resulting in multinuclearity and tumor cell death. Both compounds efficiently inhibited tumor cell proliferation in vitro (IC50 nmol/L range). In vivo, BAY 1161909 and BAY 1217389 achieved moderate efficacy in monotherapy in tumor xenograft studies. However, in line with its unique mode of action, when combined with paclitaxel, low doses of Mps1 inhibitor reduced paclitaxel-induced mitotic arrest by the weakening of SAC activity. As a result, combination therapy strongly improved efficacy over paclitaxel or Mps1 inhibitor monotreatment at the respective MTDs in a broad range of xenograft models, including those showing acquired or intrinsic paclitaxel resistance. Both Mps1 inhibitors showed good tolerability without adding toxicity to paclitaxel monotherapy. These preclinical findings validate the innovative concept of SAC abrogation for cancer therapy and justify clinical proof-of-concept studies evaluating the Mps1 inhibitors BAY 1161909 and BAY 1217389 in combination with antimitotic cancer drugs to enhance their efficacy and potentially overcome resistance. Mol Cancer Ther; 15(4); 583-92. ©2016 AACR. ©2016 American Association for Cancer Research.

Mathematical modeling of the thermal and hydrodynamic structure of the cooling reservoir

NASA Astrophysics Data System (ADS)

Saminskiy, G.; Debolskaya, E.

2012-04-01

Hydrothermal conditions of the cooling reservoir is determined by the heat and mass transfer from the water surface to the atmosphere and the processes of heat transfer directly in the water mass of the reservoir. As the capacity of power plants, the corresponding increase in the volume of heated water and the use of deep lakes and reservoirs as coolers there is a need to develop new, more accurate, and the application of existing methods for the numerical simulation. In calculating the hydrothermal regime it must take into account the effect of wind, density (buoyancy) forces, and other data of the cooling reservoir. In addition to solving practical problems it is important to know not only the magnitude of the average temperature, but also its area and depth distribution. A successful solution can be achieved through mathematical modeling of general systems of equations of transport processes and the correct formulation of the problem, based on appropriate initial data. The purpose of the work is application of software package GETM for simulating the hydrothermal regime of cooling reservoir with an estimate of three-dimensional structure of transfer processes, the effects of wind, the friction of the water surface. Three-dimensional models are rarely applied, especially for far-field problems. If such models are required, experts in the field must develop and apply them. Primary physical processes included are surface heat transfer, short-wave and long-wave radiation and penetration, convective mixing, wind and flow induced mixing, entrainment of ambient water by pumped-storage inflows, inflow density stratification as impacted by temperature and dissolved and suspended solids. The model forcing data consists of the system bathymetry developed into the model grid; the boundary condition flow and temperature; the tributary and flow and temperature; and the system meteorology. Ivankovskoe reservoir belongs to the reservoirs of valley type (Tver region, Russia). It is used as a cooling reservoir for Konakovskaya power plant. It dumps the heated water in the Moshkovichevsky bay. Thermal and hydrodynamic structure of the Moshkovichevsky Bay is particular interest as the object of direct influence of heated water discharge. To study the effect of thermal discharge into the Ivankovskoe reservoir the model of the Moshkovichevsky Bay was built, which is subject to the largest thermal pollution. Step of the calculation grid is 25 meters. For further verification of the model field investigations were conducted in August-September 2011. The modeling results satisfactorily describe the thermal and hydrodynamic structure of the Moshkovichevsky Bay.

Great Lakes and St. Lawrence Seaway Navigation Season Extension. Volume 1. Main Report and Final Environmental Impact Statement

DTIC Science & Technology

1979-08-01

MN - Taconite, MN - Silver Bay, MN - Presque Isle , MI - Marquette, MI 30 iC V.)Lake Michigan - Burns Harbor, IN - Gary, IN - Indiana, IN - Milwaukee...14,263 3.7 Presque Isle , MI 1,703 516 3.3 Marquette, MI 159 192 0.8 Taconite, MN 5,640 1,723 3.3 Silver Bay, MN 5,623 1,744 3.2 Ash-and, WI 250 668 0.4...required -for Taconite, Two Harbors, and Presque Isle and that only a single line of bubblers would be required in Ashland, MaLquette, and Silver Bay

Assessing the impacts of future climate conditions on the effectiveness of winter cover crops in reducing nitrate loads into the Chesapeake Bay Watersheds using SWAT model

USDA-ARS?s Scientific Manuscript database

Winter cover crops (WCCs) have been widely implemented in the Coastal Plain of the Chesapeake Bay watershed (CBW) due to their high effectiveness at reducing nitrate loads. However, future climate conditions (FCCs) are expected to exacerbate water quality degradation in the CBW by increasing nitrat...

78 FR 1246 - Otay River Estuary Restoration Project; South San Diego Bay Unit and Sweetwater Marsh Unit of the...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-08

...-FF08RSDC00] Otay River Estuary Restoration Project; South San Diego Bay Unit and Sweetwater Marsh Unit of the... scoping with regard to the environmental impact statement (EIS) for the proposed Otay River Estuary... one of the following methods. Email: [email protected] . Please include ``Otay Estuary NOI'' in the...

78 FR 34575 - Safety Zone; Bay Swim VI, Presque Isle Bay, Erie, PA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-10

... of any grant or loan recipients, and will not raise any novel legal or policy issues. The safety zone... through the safety zone when permitted by the Captain of the Port. 2. Impact on Small Entities Under the... entities. The Coast Guard certifies under 5 U.S.C. 605(b) that this proposed rule will not have a...

The unnatural history of Kāne'ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts.

PubMed

Bahr, Keisha D; Jokiel, Paul L; Toonen, Robert J

2015-01-01

Kāne'ohe Bay, which is located on the on the NE coast of O'ahu, Hawai'i, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāne'ohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Lo'e (Coconut Island) in the southern region of the bay became home to the Hawai'i Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960's the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of coral cover. The reefs of Kāne'ohe Bay developed under estuarine conditions and thus have been subjected to multiple natural stresses. These include storm floods, a more extreme temperature range than more oceanic reefs, high rates of sedimentation, and exposure at extreme low tides. Deposition and degradation of organic materials carried into the bay from the watershed results in low pH conditions such that according to some ocean acidification projections the rich coral reefs in the bay should not exist. Increased global temperature due to anthropogenic fossil fuel emmisions is now impacting these reefs with the first "bleaching event" in 1996 and a second more severe event in 2014. The reefs of Kāne'ohe Bay have developed and persist under rather severe natural and anthropogenic perturbations. To date, these reefs have proved to be very resilient once the stressor has been removed. A major question remains to be answered concerning the limits of Kāne'ohe Bay reef resilience in the face of global climate change.

Characterizing phosphorus speciation of Chesapeake Bay sediments using chemical extraction, 31P NMR, and X-ray absorption fine structure spectroscopy.

PubMed

Li, Wei; Joshi, Sunendra R; Hou, Guangjin; Burdige, David J; Sparks, Donald L; Jaisi, Deb P

2015-01-06

Nutrient contamination has been one of the lingering issues in the Chesapeake Bay because the bay restoration is complicated by temporally and seasonally variable nutrient sources and complex interaction between imported and regenerated nutrients. Differential reactivity of sedimentary phosphorus (P) pools in response to imposed biogeochemical conditions can record past sediment history and therefore a detailed sediment P speciation may provide information on P cycling particularly the stability of a P pool and the formation of one pool at the expense of another. This study examined sediment P speciation from three sites in the Chesapeake Bay: (i) a North site in the upstream bay, (ii) a middle site in the central bay dominated by seasonally hypoxic bottom water, and (iii) a South site at the bay-ocean boundary using a combination of sequential P extraction (SEDEX) and spectroscopic techniques, including (31)P NMR, P X-ray absorption near edge structure spectroscopy (XANES), and Fe extended X-ray absorption fine structure (EXAFS). Results from sequential P extraction reveal that sediment P is composed predominantly of ferric Fe-bound P and authigenic P, which was further confirmed by solid-state (31)P NMR, XANES, and EXAFS analyses. Additionally, solution (31)P NMR results show that the sediments from the middle site contain high amounts of organic P such as monoesters and diesters, compared to the other two sites, but that these compounds rapidly decrease with sediment depth indicating remineralized P could have precipitated as authigenic P. Fe EXAFS enabled to identify the changes in Fe mineral composition and P sinks in response to imposed redox condition in the middle site sediments. The presence of lepidocrocite, vermiculite, and Fe smectite in the middle site sediments indicates that some ferric Fe minerals can still be present along with pyrite and vivianite, and that ferric Fe-bound P pool can be a major P sink in anoxic sediments. These results provide improved insights into sediment P dynamics, particularly the rapid remineralization of organic P and the stability of Fe minerals and the ferric Fe-bound P pool in anoxic sediments in the Chesapeake Bay.

Shock-wave-induced fracturing of calcareous nannofossils from the Chesapeake Bay impact crater

USGS Publications Warehouse

,

2003-01-01

Fractured calcareous nannofossils of the genus Discoaster from synimpact sediments within the Chesapeake Bay impact crater demonstrate that other petrographic shock indicators exist for the cratering process in addition to quartz minerals. Evidence for shock-induced taphonomy includes marginal fracturing of rosette-shaped Discoaster species into pentagonal shapes and pressure- and temperature-induced dissolution of ray tips and edges of discoasters. Rotational deformation of individual crystallites may be the mechanism that produces the fracture pattern. Shock-wave-fractured calcareous nannofossils were recovered from synimpact matrix material representing tsunami or resurge sedimentation that followed impact. Samples taken from cohesive clasts within the crater rubble show no evidence of shock-induced fracturing. The data presented here support growing evidence that microfossils can be used to determine the intensity and timing of wet-impact cratering.

Contaminant transport in Massachusetts Bay

USGS Publications Warehouse

Butman, Bradford

Construction of a new treatment plant and outfall to clean up Boston Harbor is currently one of the world's largest public works projects, costing about $4 billion. There is concern about the long-term impact of contaminants on Massachusetts Bay and adjacent Gulf of Maine because these areas are used extensively for transportation, recreation, fishing, and tourism, as well as waste disposal. Public concern also focuses on Stellwagen Bank, located on the eastern side of Massachusetts Bay, which is an important habitat for endangered whales. Contaminants reach Massachusetts Bay not only from Boston Harbor, but from other coastal communities on the Gulf of Maine, as well as from the atmosphere. Knowledge of the pathways, mechanisms, and rates at which pollutants are transported throughout these coastal environments is needed to address a wide range of management questions.

First results on the Experiment FESTER on optical turbulence over False Bay South Africa: dependencies and consequences

NASA Astrophysics Data System (ADS)

Sprung, Detlev; van Eijk, Alexander M. J.; Sucher, Erik; Eisele, Christian; Seiffer, Dirk; Stein, Karin

2016-10-01

The experiment FESTER (First European South African Transmission ExpeRiment) took place in 2015 to investigate the atmospheric influence on electro-optical systems performance across False Bay / South Africa on a long term basis. Several permanent stations for monitoring electro-optical propagation and atmospheric parameters were set up around the Bay. Additional intensive observation periods (IOPs) allowed for boat runs to assess the inhomogeneous atmospheric propagation conditions over water. In this paper we focus on the distribution of optical turbulence over the Bay. The different impact of water masses originating from the Indian Ocean and the Benguela current on the development of optical turbulence is discussed. The seasonal behavior of optical turbulence is presented and its effect on electro-optical system performance examined.

Bayes and the Law.

PubMed

Fenton, Norman; Neil, Martin; Berger, Daniel

2016-06-01

Although the last forty years has seen considerable growth in the use of statistics in legal proceedings, it is primarily classical statistical methods rather than Bayesian methods that have been used. Yet the Bayesian approach avoids many of the problems of classical statistics and is also well suited to a broader range of problems. This paper reviews the potential and actual use of Bayes in the law and explains the main reasons for its lack of impact on legal practice. These include misconceptions by the legal community about Bayes' theorem, over-reliance on the use of the likelihood ratio and the lack of adoption of modern computational methods. We argue that Bayesian Networks (BNs), which automatically produce the necessary Bayesian calculations, provide an opportunity to address most concerns about using Bayes in the law.

Fluvial fluxes from the Magdalena River into Cartagena Bay, Caribbean Colombia: Trends, future scenarios, and connections with upstream human impacts

NASA Astrophysics Data System (ADS)

Restrepo, Juan D.; Escobar, Rogger; Tosic, Marko

2018-02-01

Fluxes of continental runoff and sediments as well as downstream deposition of eroded soils have severely altered the structure and function of fluvial and deltaic-estuarine ecosystems. The Magdalena River, the main contributor of continental fluxes into the Caribbean Sea, delivers important amounts of water and sediments into Cartagena Bay, a major estuarine system in northern Colombia. Until now, trends in fluvial fluxes into the bay, as well as the relationship between these tendencies in fluvial inputs and associated upstream changes in the Magdalena catchment, have not been studied. Here we explore the interannual trends of water discharge and sediment load flowing from the Magdalena River-Canal del Dique system into Cartagena Bay during the last three decades, forecast future scenarios of fluxes into the bay, and discuss possible connections between observed trends in fluvial inputs and trends in human intervention in the Magdalena River basin. Significant upward trends in annual runoff and sediment load during the mid-1980s, 1990s, and post-2000 are observed in the Magdalena and in the Canal del Dique flowing into Cartagena Bay. During the last decade, Magdalena streamflow and sediment load experienced increases of 24% and 33%, respectively, compared to the pre-2000 year period. Meanwhile, the Canal del Dique witnessed increases in water discharge and sediment load of 28% and 48%, respectively. During 26 y of monitoring, the Canal del Dique has discharged 177 Mt of sediment to the coastal zone, of which 52 Mt was discharged into Cartagena Bay. Currently, the Canal drains 6.5% and transports 5.1% of the Magdalena water discharge and sediment load. By 2020, water discharge and sediment flux from the Canal del Dique flowing to the coastal zone will witness increments of 164% and 260%, respectively. Consequently, sediment fluxes into Cartagena Bay will witness increments as high as 8.2 Mt y- 1 or 317%. Further analyses of upstream sediment load series for 21 tributary systems of the main Magdalena during the 2005-2010 period reveal that six tributaries, representing 55% of the analyzed Magdalena basin area, have witnessed increasing trends in sediment load, raising the river's sediment load by 44 Mt y- 1. Overall, trends in sediment load of the Magdalena and the Canal del Dique during the last three decades are in close agreement with the observed trends in human induced upstream erosion. The last decade has witnessed even stronger increments in fluvial fluxes to Cartagena Bay. Our results emphasize the importance of the catchment-coast linkage in order to predict future changes of fluvial fluxes into Caribbean estuarine systems.

Structuring of Bacterioplankton Diversity in a Large Tropical Bay

PubMed Central

Gregoracci, Gustavo B.; Nascimento, Juliana R.; Cabral, Anderson S.; Paranhos, Rodolfo; Valentin, Jean L.; Thompson, Cristiane C.; Thompson, Fabiano L.

2012-01-01

Structuring of bacterioplanktonic populations and factors that determine the structuring of specific niche partitions have been demonstrated only for a limited number of colder water environments. In order to better understand the physical chemical and biological parameters that may influence bacterioplankton diversity and abundance, we examined their productivity, abundance and diversity in the second largest Brazilian tropical bay (Guanabara Bay, GB), as well as seawater physical chemical and biological parameters of GB. The inner bay location with higher nutrient input favored higher microbial (including vibrio) growth. Metagenomic analysis revealed a predominance of Gammaproteobacteria in this location, while GB locations with lower nutrient concentration favored Alphaproteobacteria and Flavobacteria. According to the subsystems (SEED) functional analysis, GB has a distinctive metabolic signature, comprising a higher number of sequences in the metabolism of phosphorus and aromatic compounds and a lower number of sequences in the photosynthesis subsystem. The apparent phosphorus limitation appears to influence the GB metagenomic signature of the three locations. Phosphorus is also one of the main factors determining changes in the abundance of planktonic vibrios, suggesting that nutrient limitation can be observed at community (metagenomic) and population levels (total prokaryote and vibrio counts). PMID:22363639

Modeling the fate of p,p'-DDT in water and sediment of two typical estuarine bays in South China: Importance of fishing vessels' inputs.

PubMed

Fang, Shu-Ming; Zhang, Xianming; Bao, Lian-Jun; Zeng, Eddy Y

2016-05-01

Antifouling paint applied to fishing vessels is the primary source of dichloro-diphenyl-trichloroethane (DDT) to the coastal marine environments of China. With the aim to provide science-based support of potential regulations on DDT use in antifouling paint, we utilized a fugacity-based model to evaluate the fate and impact of p,p'-DDT, the dominant component of DDT mixture, in Daya Bay and Hailing Bay, two typical estuarine bays in South China. The emissions of p,p'-DDT from fishing vessels to the aquatic environments of Hailing Bay and Daya Bay were estimated as 9.3 and 7.7 kg yr(-1), respectively. Uncertainty analysis indicated that the temporal variability of p,p'-DDT was well described by the model if fishing vessels were considered as the only direct source, i.e., fishing vessels should be the dominant source of p,p'-DDT in coastal bay areas of China. Estimated hazard quotients indicated that sediment in Hailing Bay posed high risk to the aquatic system, and it would take at least 21 years to reduce the hazards to a safe level. Moreover, p,p'-DDT tends to migrate from water to sediment in the entire Hailing Bay and Daya Bay. On the other hand, our previous research indicated that p,p'-DDT was more likely to migrate from sediment to water in the maricultured zones located in shallow waters of these two bays, where fishing vessels frequently remain. These findings suggest that relocating mariculture zones to deeper waters would reduce the likelihood of farmed fish contamination by p,p'-DDT. Copyright © 2016 Elsevier Ltd. All rights reserved.

Studies on Anthropogenic Impact on Water Quality in Hilo (Hawaii) Bay and Mapping the Study Stations Using Geospatial Technologies

NASA Astrophysics Data System (ADS)

Cartier, A. J.; Williams, M. S.; Adolf, J.; Sriharan, S.

2015-12-01

Hilo Bay has uncharacteristically brown waters compared to other waters found in Hawai'i. The majority of the freshwater entering Hilo Bay is from storm and surface water runoff. The anthropogenic impact on water quality at Hilo Bay is due to sediment entrance, cesspools (Bacteria), and invasive species (Albizia). This poster presentation will focus on the water quality and phytoplankton collected on a weekly basis at a buoy positioned one meter from the shore of Hilo Bay, preserving the phytoplankton intact, concentrating and dehydrating the sample with ethanol, and viewing the phytoplankton with a scanning electron microscope (Hitachi S-3400NII). The GPS (Global Positioning System) points were collected at the sampling stations. Three transects on three separate dates were performed in Hilo Bay with salinity, percent dissolved oxygen, turbidity, secchi depth, temperature, and chlorophyll fluorescence data collected at each sampling station. A consistent trend observed in all transects was as distance from the river increased turbidity decreased and salinity increased. The GPS data on June 30, 2015 showed a major correlation between stations and their distance from shore. There is a decrease in the turbidity but not the temperature for these stations. The GPS points collected on July 7, 2015 at thirteen stations starting with station one being at the shore to the water, showed that the salinity concentration fluctuate noticeably at the first 6 stations. As we proceed further away from the shore, the salinity concentration increases from stations seven through thirteen. The water temperature shows little variation throughout the thirteen stations. The turbidity level was high at the shore and shows a noticeable drop at station thirteen.

Geochemical analysis of sediments from a semi-enclosed bay (Dongshan Bay, southeast China) to determine the anthropogenic impact and source.

PubMed

Xu, Yonghang; Sun, Qinqin; Ye, Xiang; Yin, Xijie; Li, Dongyi; Wang, Liang; Wang, Aijun; Li, Yunhai

2017-05-01

The geochemical compositions of sediments in the Dongshan Bay, a semi-enclosed bay on the southeast coast of China, were obtained to identify pollutant sources and evaluate the anthropogenic impacts over the last 100 years. The results indicated that the metal flux had been increasing since the 1980s. Enrichment factor values (Pb, Zn and Cu) suggested only slight enrichment. The proportion of anthropogenic Pb changed from 9% to 15% during 2000-2014. Coal combustion might be an important contamination source in the Dongshan Bay. The historical variation in the metal flux reflected the economic development and urbanization in the Zhangjiang drainage area in the past 30 years. According to the Landsat satellite remote sensing data, the urbanization area expanded approximately three times from 1995 to 2010. The δ 13 C values (-21‰ to -23‰) of the organic matter (OM) in the sediments indicated that the OM was primarily sourced from aquatic, terrigenous and marsh C 3 plants. Nitrogen was mainly derived from aquatic plants and terrigenous erosion before the 1980s. However, the total organic carbon (TOC) contents, total nitrogen (TN) contents and δ 15 N had been increasing since the 1980s, which suggested that the sources of nitrogen were soil erosion, fertilizer and sewage. In addition, the TOC and TN fluxes in the Dongshan Bay had significantly increased since the 1980s, which reflected the use of N fertilizer. However, the TOC and TN fluxes significantly decreased in the past decade because environmental awareness increased and environmental protection policies were implemented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Responses of water environment to tidal flat reduction in Xiangshan Bay: Part II locally re-suspended sediment dynamics

NASA Astrophysics Data System (ADS)

Li, Li; Guan, Weibing; He, Zhiguo; Yao, Yanming; Xia, Yuezhang

2017-11-01

Xiangshan Bay is a semi-enclosed bay in China, in which tidal flats have been substantially reclaimed to support the development of local economies and society over previous decades. The loss of tidal flats has led to changes of tides and locally suspended sediment in the bay. The effects of tidal flat reduction on locally suspended sediment dynamics was investigated using a numerical model forced by tidal data and calibrated by observed tidal elevation and currents. The model satisfactorily reproduces observed water levels, currents, and suspended sediment concentration in the estuary, and therefore is subsequently applied to analyze the impact of tidal flat reclamation on locally suspended sediment transport. After the loss of the tidal flats from 1963 to 2010, the suspended sediment concentrations (SSC) at the bottom boundary layer were reduced/increased in the outer bay/tidal flat areas due to weakened tidal currents. In the inner bay, the SSC values near the bottom level increased from 1963 to 2003 due to the narrowed bathymetry, and then decreased from 2003 to 2010 because of the reduced tidal prism. The model scenarios suggest that: (1) a reduction of tidal flat areas appears to be the main factor for enhancing the transport of sediments up-estuary, due to the increased Eulerian velocity and tidal pumping; (2) A reduction of tidal flat areas impacts on spatial and temporal SSC distribution: reducing the SSC values in the water areas due to the reduced current; and (3) a tidal flat reduction influences the net sediment fluxes: lessening the erosion and inducing higher/lower landward/seaward sediment transportation.

Potential impact of an exceptional bloom of Karenia mikimotoi on dissolved oxygen levels in waters off western Ireland.

PubMed

O'Boyle, Shane; McDermott, Georgina; Silke, Joe; Cusack, Caroline

2016-03-01

In the summer of 2005 an exceptional bloom of the dinoflagellate Karenia mikimotoi occurred along Ireland's Atlantic seaboard and was associated with the mass mortality of both benthic and pelagic marine life. Oxygen depletion, cellular toxicity and physical smothering, are considered to be the main factors involved in mortality. In this paper we use a theoretical approach based on stoichiometry (the Anderson ratio) and an average K. mikimotoi cellular carbon content of 329pgCcell -1 (n=20) to calculate the carbonaceous and nitrogenous oxygen demand following bloom collapse. The method was validated against measurements of biochemical oxygen demand and K. mikimotoi cell concentration. The estimated potential oxygen utilisation (POU) was in good agreement with field observations across a range of cell concentrations. The magnitude of POU following bloom collapse, with the exception of three coastal areas, was considered insufficient to cause harm to most marine organisms. This indicates that the widespread occurrence of mortality was primarily due to other factors such as cellular toxicity and/or mucilage production, and not oxygen depletion or related phenomena. In Donegal Bay, Kilkieran Bay and inner Dingle Bay, where cell densities were in the order of 10 6 cellsL -1 , estimated POU was sufficient to cause hypoxia. Of the three areas, Donegal Bay is considered to be the most vulnerable due to its hydrographic characteristics (seasonally stratified, weak residual flow) and hypoxic conditions (2.2mgL -1 O 2 ) were directly observed in the Bay post bloom collapse. Here, depending on the time of bloom collapse, depressed DO levels could persist for weeks and continue to have a potentially chronic impact on the Bay. Copyright © 2015 Elsevier B.V. All rights reserved.

Ecological studies related to the construction of the Defense Waste Processing Facility on the Savannah River Site. Annual report, FY-1991 and FY-1992

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

Scott, D.E.; Chazel, A.C.; Pechmann, J.H.K.

1993-06-01

The Defense Waste Processing Facility (DWPF) was built on the Savannah River Site (SRS) during the mid-1980`s. The Savannah River Ecology Laboratory (SREL) has completed 14 years of ecological studies related to the construction of the DWPF complex. Prior to construction, the 600-acre site (S-Area) contained a Carolina bay and the headwaters of a stream. Research conducted by the SREL has focused primarily on four questions related to these wetlands: (1) Prior to construction, what fauna and flora were present at the DWPF site and at similar, yet undisturbed, alternative sites? (2) By comparing the Carolina bay at the DWPFmore » site (Sun Bay) with an undisturbed control Carolina bay (Rainbow Bay), what effect is construction having on the organisms that inhabited the DWPF site? (3) By comparing control streams with streams on the periphery of the DWPF site, what effect is construction having on the peripheral streams? (4) How effective have efforts been to lessen the impacts of construction, both with respect to erosion control measures and the construction of ``refuge ponds`` as alternative breeding sites for amphibians that formerly bred at Sun Bay? Through the long-term census-taking of biota at the DWPF site and Rainbow Bay, SREL has begun to evaluate the impact of construction on the biota and the effectiveness of mitigation efforts. Similarly, the effects of erosion from the DWPF site on the water quality of S-Area peripheral streams are being assessed. This research provides supporting data relevant to the National Environmental Policy Act (NEPA) of 1969, the Endangered Species Act of 1973, Executive Orders 11988 (Floodplain Management) and 11990 (Protection of Wetlands), and United States Department of Energy (DOE) Guidelines for Compliance with Floodplain/Wetland Environmental Review Requirements (10 CFR 1022).« less

The History of Land-Use Change in the South Florida Ecosystem: Paleoecologic Data as a Guide for Restoration

NASA Astrophysics Data System (ADS)

Wingard, G. L.; Cronin, T. M.; Dwyer, G. S.; Holmes, C. W.; Ishman, S. E.

2003-12-01

The south Florida ecosystem has undergone profound changes during the last century as a result of urbanization, agricultural development, and the construction of a massive water control system - the Central and Southern Florida (C&SF) Project. Created in 1948, the C&SF Project was designed for flood protection and to provide water for people and agricultural development. The extensive network of canals, levees, and water-control structures cover over 18,000 square miles and have completely altered the natural sheet flow of water across the land. Water was, and is, the principal driving force of this unique subtropical ecosystem, a significant portion of which is public land, including Everglades National Park, Biscayne National Park, Big Cypress National Preserve, the Florida Keys National Marine Sanctuary, Dry Tortugas National Park, and six National Wildlife Refuge Complexes. The Comprehensive Everglades Restoration Plan (CERP) has been designed in an effort to restore more natural water delivery to the ecosystem. This plan will cost over 8 billion dollars and take more than 30 years to complete. To successfully implement the CERP, land managers and restoration planners need answers to questions such as what are our restoration targets? What conditions are we restoring the system to? What portion of the changes seen in the 20th century can be attributed to land-use changes and what portion to natural change? What are the impacts on living resources? Paleoecologic and biochemical research is providing the answers to these questions. Analyses of cores from Florida Bay and Biscayne Bay have highlighted the following important findings. (1) Although land-use changes have played a role in determining salinity for Florida Bay as a whole, salinity is more strongly correlated to rainfall than any other single factor. (2) Anthropogenic activity influences the magnitude of salinity variations seen in recent times in Florida Bay, and they probably act on a local basis to influence salinity patterns near areas of canal outflow. (3) Declines in species diversity and increases in dominance of salinity-tolerant species have occurred since the 1980s in several benthic invertebrate groups in different regions of Florida Bay. (4) Increases in abundance and/or density of sub-aquatic vegetation appear to have occurred in the last 50 years, compared to the first half of the 20th century. 5) In central Biscayne Bay salinities have become increasingly marine and increasingly stable over the last century. (6) Southern Biscayne Bay has experienced relatively large swings in salinity over multi-decadal and centennial timescales, but marine influence at the site has increased over the last century. (7) Sub-aquatic vegetation in Biscayne Bay has undergone bay-wide patterns of change over the last 200-500 years but a decline in Thalassia appears to have occurred in central Biscayne Bay around the middle of the 20th century. These findings are providing land management agencies with the information they need to plan and prioritize restoration effectively.

Sediment dispersal in modern and mid-Holocene basins: implications for shoreline progradation and sediment bypassing, Poverty Bay, New Zealand

NASA Astrophysics Data System (ADS)

Bever, A. J.; Harris, C. K.; McNinch, J.

2006-12-01

Poverty Bay is a small embayment located on the eastern shore of New Zealand's North Island. The modern Waipaoa River, a small mountainous river that drains highly erodible mudstone and siltstone, discharges ~15 million tons of sediment per year to Poverty Bay. Rates of bay infilling from fluvial sediment have varied since the maximum shoreline transgression, ~7000 kya. The evolving geometry of Poverty Bay has likely impacted sediment dispersal over these timescales, and thereby influenced the stratigraphic architecture, rates of shoreline progradation, and sediment supply to the continental shelf. This modeling study investigates sediment transport within both modern and paleo, ~7000 kya, Poverty Bays. The Regional Ocean Modeling System was used to examine sediment transport within modern and ~7000 kya Poverty Bay basin geometries. The numerical model includes hydrodynamics driven by winds and buoyancy, and sediment resuspension from energetic waves and currents. Strong winds and waves from the southeast were used, along with high Waipaoa freshwater and sediment discharge, consistent with storm conditions. Besides shedding light on short term transport mechanisms, these results are being incorporated into a stratigraphic model by Wolinsky and Swenson. The paleo basin geometry narrowed at the head of the bay, causing currents to converge and promoting near- field sediment deposition. Buoyancy and wind driven across-shelf currents in the modern bay transport sediment away from the river mouth. Sediment was deposited closer to the river mouth in the paleo than the modern bay, and the modern bay exported much more sediment to the continental shelf than predicted for the middle Holocene bay. Net across-shelf fluxes decreased from a maximum at the head of the bay to nearly zero at the mouth during the paleo run. The modern run, however, had net across-shelf fluxes still half the maximum at the bay mouth. Results from short term model runs indicated that, with similar river discharges, the 7000 kya Poverty Bay shoreline should have prograded rapidly as sediment was deposited near the river mouth at the head of the bay, an area of little accommodation space. The trapping of sediment within the bay would have lead to a relatively sediment starved continental shelf. As the river mouth progressed towards the wider section of the bay, progradation should have been reduced as both proximal accommodation space and sediment export to the continental shelf increased.

Impact of human activities on subaqueous topographic change in Lingding Bay of the Pearl River estuary, China, during 1955–2013

PubMed Central

Wu, Z. Y.; Saito, Yoshiki; Zhao, D. N.; Zhou, J. Q.; Cao, Z. Y.; Li, S. J.; Shang, J. H.; Liang, Y. Y.

2016-01-01

Estuaries have been sites of intensive human activities during the past century. Tracing the evolution of subaqueous topography in estuaries on a decadal timescale enables us to understand the effects of human activities on estuaries. Bathymetric data from 1955 to 2010 show that land reclamation decreased the subaqueous area of Lingding Bay, in the Pearl River estuary, by ~170 km2 and decreased its water volume by 615 × 106 m3, representing a net decrease of 11.2 × 106 m3 per year and indicating the deposition of approximately 14.5 Mt/yr of sediment in Lingding Bay during that period. Whereas Lingding Bay was mainly governed by natural processes with slight net deposition before 1980, subsequent dredging and large port engineering projects changed the subaqueous topography of the bay by shallowing its shoals and deepening its troughs. Between 2012 and 2013, continuous dredging and a surge of sand excavation resulted in local changes in water depth of ± 5 m/yr, far exceeding the magnitude of natural topographic evolution in Lingding Bay. Reclamation, dredging, and navigation-channel projects removed 8.4 Mt/yr of sediment from Lingding Bay, representing 29% of the sediment input to the bay, and these activities have increased recently. PMID:27886227

Over 100 years of environmental change recorded by foraminifers and sediments in a large Gulf of Mexico estuary, Mobile Bay, AL, USA

USGS Publications Warehouse

Osterman, Lisa E.; Smith, Christopher G.

2012-01-01

The marine microfauna of Mobile Bay has been profoundly influenced by the development and expansion of the primary shipping channel over the last ˜100 years. Foraminifers and sediments from seven box cores with excess lead-210 chronology document that channel dredging and spoil disposal have altered circulation, reduced estuarine mixing, changed sedimentation patterns, and caused a faunal turnover within the bay. Beginning in the late 1800s, changes in estuarine mixing allowed for greater low-pH freshwater influence in the bay, and ultimately began environmental changes that resulted in the loss of calcareous foraminifers. By the early 1900s, box cores throughout Mobile Bay record a ˜ 100-year trend of increasing calcareous test dissolution that continues to the present. Since the completion of the current shipping channel in the 1950s, restricted tidal flushing and increased terrestrial organic matter, documented by carbon-to-nitrogen ratios, stimulated an increase in agglutinated foraminiferal densities. However, in deeper areas of the bay, hypoxic water has negatively impacted the marine microfauna. Comparisons of the present-day foraminiferal assemblage with foraminifers collected in the early 1970s indicate that the continued biologic loss of calcareous foraminifers in the bay has allowed the introduction of a new agglutinated foraminiferal species into the bay.

Spatial variations in zooplankton community structure along the Japanese coastline in the Japan Sea: influence of the coastal current

NASA Astrophysics Data System (ADS)

Kodama, Taketoshi; Wagawa, Taku; Iguchi, Naoki; Takada, Yoshitake; Takahashi, Takashi; Fukudome, Ken-Ichi; Morimoto, Haruyuki; Goto, Tsuneo

2018-06-01

This study evaluates spatial variations in zooplankton community structure and potential controlling factors along the Japanese coast under the influence of the coastal branch of the Tsushima Warm Current (CBTWC). Variations in the density of morphologically identified zooplankton in the surface layer in May were investigated for a 15-year period. The density of zooplankton (individuals per cubic meter) varied between sampling stations, but there was no consistent west-east trend. Instead, there were different zooplankton community structures in the west and east, with that in Toyama Bay particularly distinct: Corycaeus affinis and Calanus sinicus were dominant in the west and Oithona atlantica was dominant in Toyama Bay. Distance-based redundancy analysis (db-RDA) was used to characterize the variation in zooplankton community structure, and four axes (RD1-4) provided significant explanation. RD2-4 only explained < 4.8 % of variation in the zooplankton community and did not show significant spatial difference; however, RD1, which explained 89.9 % of variation, did vary spatially. Positive and negative species scores on RD1 represent warm- and cold-water species, respectively, and their variation was mainly explained by water column mean temperature, and it is considered to vary spatially with the CBTWC. The CBTWC intrusion to the cold Toyama Bay is weak and occasional due to the submarine canyon structure of the bay. Therefore, the varying bathymetric characteristics along the Japanese coast of the Japan Sea generate the spatial variation in zooplankton community structure, and dominance of warm-water species can be considered an indicator of the CBTWC.

75 FR 71731 - Notice of Availability of the Record of Decision for the Harvest of Glaucous-Winged Gull Eggs by...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-24

... for the Harvest of Glaucous-Winged Gull Eggs by Huna Tlingit in Glacier Bay National Park and Preserve... availability of the Record of Decision for the Harvest of Glaucous-Winged Gull Eggs by Huna Tlingit in Glacier... Impact Statement (LEIS) on the Harvest of Glaucous-Winged Gull Eggs by Huna Tlingit in Glacier Bay...

Estimating nitrogen loading and far-field dispersal potential from background sources and coastal finfish aquaculture: A simple framework and case study in Atlantic Canada

NASA Astrophysics Data System (ADS)

McIver, R.; Milewski, I.; Loucks, R.; Smith, R.

2018-05-01

Far-field nutrient impacts associated with finfish aquaculture have been identified as a topic of concern for regulators, managers, scientists, and the public for over two decades but disentangling aquaculture impacts from those caused by other natural and anthropogenic sources has impeded the development of monitoring metrics and management plans. We apply a bulk, steady-state nitrogen loading model (NLM) framework to estimate the annual input of Total Dissolved Nitrogen (TDN) from point and non-point sources to the watershed surrounding Port Mouton Bay, Nova Scotia (Canada). We then use the results of the NLM together with estimates of dissolved inorganic nitrogen (DIN) loading from a sea-cage trout farm in the Bay and progressive vector diagrams to illustrate potential patterns of DIN dispersal from the trout farm. Our estimated anthropogenic nitrogen contribution to Port Mouton Bay from all terrestrial and atmospheric sources is ∼211,703 kg TDN/year with atmospheric deposition accounting for almost all (98.6%). At a stocking level of ∼400,000 rainbow trout, the Port Mouton Bay sea-cage farm increases the annual anthropogenic TDN loading to the bay by 14.4% or 30,400 kg. Depending on current flow rates, nitrogen flux from the trout farm can be more than double the background concentrations of TDN near the farm site. Although it is unlikely that nitrogen loading from this single fish farm is saturating the DIN requirements of the entire bay, progressive vector diagrams suggest that the dispersal potential may be insufficient to mitigate potential symptoms of eutrophication associated with nitrogen fluxes. We present an accessible and user-friendly tool for managers to estimate baseline nutrient loading in relation to aquaculture and our use of progressive vector diagrams illustrate a practical and simple method for characterizing potential nutrient dispersal based on local conditions and spatial scales. Our study joins numerous studies which have highlighted the need for more effective monitoring and assessment methods to improve the detection of aquaculture effects at far-field scales and to assess those effects in relation to other natural and anthropogenic factors impacting coastal habitats.

Storm impacts and shoreline recovery: Mechanisms and controls in the southern North Sea

NASA Astrophysics Data System (ADS)

Brooks, S. M.; Spencer, T.; Christie, E. K.

2017-04-01

Storm impacts play a significant role in shoreline dynamics on barrier coastlines. Furthermore, inter-storm recovery is a key parameter determining long-term coastal resilience to climate change, storminess variability and sea level rise. Over the last decade, four extreme storms, with strong energetic waves and high still water levels resulting from high spring tides and large skew surge residuals, have impacted the shoreline of the southern North Sea. The 5th December 2013 storm, with the highest run-up levels recorded in the last 60 years, resulted in large sections of the frontline of the North Norfolk coast being translated inland by over 10 m. Storms in March and November 2007 also generated barrier scarping and shoreline retreat, although not on the scale of 2013. Between 2008 and 2013, a calm period, recovery dominated barrier position and elevation but was spatially differentiated alongshore. For one study area, Scolt Head Island, no recovery was seen; this section of the coast is being reset episodically landwards during storms. By contrast, the study area at Holkham Bay showed considerable recovery between 2008 and 2013, with barrier sections developing seaward through foredune recovery. The third study area, Brancaster Bay, showed partial recovery in barrier location and elevation. Results suggest that recovery is promoted by high sediment supply and onshore intertidal bar migration, at rates of 40 m a- 1. These processes bring sand to elevations where substrate drying enables aeolian processes to entrain and transport sand from upper foreshores to foredunes. We identify three potential sediment transport pathways that create a region of positive diffusivity at Holkham Bay. During calm periods, a general westward movement of sediment from the drift divide at Sheringham sources the intertidal bar and foredune development at Holkham Bay. However, during and following storms the drift switches to eastward, not only on the beach itself but also below the - 7 m isobath. Sediment from the eroding barrier at Brancaster Bay, and especially Scolt Head Island, also sources the sediment sink of Holkham Bay. Knowledge of foredune growth and barrier recovery in natural systems are vital aspects of future coastal management planning with accelerated sea-level rise and storminess variability.

Chemical speciation and ecological risk assessment of arsenic in marine sediments from Izmir Bay (Eastern Aegean Sea).

PubMed

Gonul, L T

2015-12-01

Total arsenic, arsenic(III) and (V), Fe, and Mn were measured in 17 surface sediment samples from Izmir Bay. The concentrations and ecological risk of As were characterized in the sediment affected by urban and agricultural activities. Total As ranged from 8.87 to 28.3 μg g(-1) dry weight (96.5-99.9 % as inorganic As). Distribution of total As and total As/Fe followed a different trend in sediments at all sampling sites. Arsenite (As(III)) was the most dominant form followed by As(V), while organic arsenic represented a minor constituent (0.03 to 3.49 %). The highest concentration of total As was observed at Gediz River estuary and exceeded lower threshold value (threshold effects level (TEL)). Due to the biological reduction of As(V) and abundance of Fe (oxyhydr)oxides in the sediments, most inorganic As in the Izmir Bay was present as As(III). Besides, the levels of As were >TEL and

U.S. Geological Survey Chesapeake Bay Studies: Scientific Solutions for a Healthy Bay and Watershed

USGS Publications Warehouse

Phillips, Scott

2006-01-01

Since the mid-1980s, the USGS has been an active partner in the Chesapeake Bay Program (CBP), a multi-agency partnership led by the U.S. Environmental Protection Agency, working to achieve the restoration goals set forth in the Chesapeake 2000 agreement. This agreement established over 100 restoration commitments to be addressed by 2010. In 2005, which was the mid-point of the agreement, there was growing concern at all levels of government and by the public that ecological conditions in the Bay and its watershed had not significantly improved. The slow rate of improvement, coupled with the projected impact of human-population increase in the Bay watershed (fig. 1), implied that many desired ecological conditions will not be achieved by 2010. To address these challenges, the USGS wrote a new science plan for 2006-2011, and is synthesizing key findings to highlight the accomplishments from science activities for 2000-2005.

Assessing wetland loss impacts on watershed hydrology using an improved modeling approach

USDA-ARS?s Scientific Manuscript database

Despite the importance of wetland impacts on water cycling, the Chesapeake Bay Watershed (CBW) has experienced significant wetland losses. The resultant environmental degradation has not been fully characterized. Our aim is to assess wetland loss impacts on watershed hydrology for an agricultural wa...

Automatic Bayes Factors for Testing Equality- and Inequality-Constrained Hypotheses on Variances.

PubMed

Böing-Messing, Florian; Mulder, Joris

2018-05-03

In comparing characteristics of independent populations, researchers frequently expect a certain structure of the population variances. These expectations can be formulated as hypotheses with equality and/or inequality constraints on the variances. In this article, we consider the Bayes factor for testing such (in)equality-constrained hypotheses on variances. Application of Bayes factors requires specification of a prior under every hypothesis to be tested. However, specifying subjective priors for variances based on prior information is a difficult task. We therefore consider so-called automatic or default Bayes factors. These methods avoid the need for the user to specify priors by using information from the sample data. We present three automatic Bayes factors for testing variances. The first is a Bayes factor with equal priors on all variances, where the priors are specified automatically using a small share of the information in the sample data. The second is the fractional Bayes factor, where a fraction of the likelihood is used for automatic prior specification. The third is an adjustment of the fractional Bayes factor such that the parsimony of inequality-constrained hypotheses is properly taken into account. The Bayes factors are evaluated by investigating different properties such as information consistency and large sample consistency. Based on this evaluation, it is concluded that the adjusted fractional Bayes factor is generally recommendable for testing equality- and inequality-constrained hypotheses on variances.

Map showing thickness of young bay mud, southern San Francisco Bay, California

USGS Publications Warehouse

McDonald, Sandra D.; Nichols, Donald R.; Wright, Nancy A.; Atwater, Brian

1978-01-01

Soft water-saturated estuarine deposits less than 10,000 years old underlie the southern part of San Francisco bay and the present and former marshlands that border the bay. Known locally as bay mud or as young bay mud, these deposits, and the estuarine environment that produces them, are of major importance in making decision on land use and development in the San Francisco Bay area. Knowledge of the distribution, thickness, and physical properties of young bay mud is critical to the feasibility, design, and maintenance of structures built on it. Fore this reason, numerous attempts have been made in the past to map or describe these characteristics (Mitchell, 1963; Goldman, 1969; McDonald and Nichols, 1974). The accompanying map of bay-mud thickness significantly revises part of an earlier compilation by Kahle and Goldman (1969) and includes new data from approximately 2400 boreholes, most of which have been drilled during the past 15 years. It also incorporates information on historic margins of San Francisco Bay and its tidal marshes (Nichols and Wright, 1971). Although this map was compelled mostly from data gathered during foundation investigations and construction projects, it is mostly from data gathered during foundation investigations and construction projects, it is not a substitute for such studies. Rather, the map provides regional information for land-use planning, seismic zonation, and design of foundation investigations.

Finite Element Based HWB Centerbody Structural Optimization and Weight Prediction

NASA Technical Reports Server (NTRS)

Gern, Frank H.

2012-01-01

This paper describes a scalable structural model suitable for Hybrid Wing Body (HWB) centerbody analysis and optimization. The geometry of the centerbody and primary wing structure is based on a Vehicle Sketch Pad (VSP) surface model of the aircraft and a FLOPS compatible parameterization of the centerbody. Structural analysis, optimization, and weight calculation are based on a Nastran finite element model of the primary HWB structural components, featuring centerbody, mid section, and outboard wing. Different centerbody designs like single bay or multi-bay options are analyzed and weight calculations are compared to current FLOPS results. For proper structural sizing and weight estimation, internal pressure and maneuver flight loads are applied. Results are presented for aerodynamic loads, deformations, and centerbody weight.

Petrographic and geochemical comparisons between the lower crystalline basement-derived section and the granite megablock and amphibolite megablock of the Eyreville B core, Chesapeake Bay impact structure, USA

USGS Publications Warehouse

Townsend, G.N.; Gibson, R.L.; Horton, J. Wright; Reimold, W.U.; Schmitt, R.T.; Bartosova, K.

2009-01-01

The Eyreville B core from the Chesapeake Bay impact structure, Virginia, USA, contains a lower basement-derived section (1551.19 m to 1766.32 m deep) and two megablocks of dominantly (1) amphibolite (1376.38 m to 1389.35 m deep) and (2) granite (1095.74 m to 1371.11 m deep), which are separated by an impactite succession. Metasedimentary rocks (muscovite-quartz-plagioclase-biotite-graphite ?? fibrolite ?? garnet ?? tourmaline ?? pyrite ?? rutile ?? pyrrhotite mica schist, hornblende-plagioclase-epidote-biotite- K-feldspar-quartz-titanite-calcite amphibolite, and vesuvianite-plagioclase- quartz-epidote calc-silicate rock) are dominant in the upper part of the lower basement-derived section, and they are intruded by pegmatitic to coarse-grained granite (K-feldspar-plagioclase-quartz-muscovite ?? biotite ?? garnet) that increases in volume proportion downward. The granite megablock contains both gneissic and weakly or nonfoliated biotite granite varieties (K-feldspar-quartz-plagioclase-biotite ?? muscovite ?? pyrite), with small schist xenoliths consisting of biotite-plagioclase-quartz ?? epidote ?? amphibole. The lower basement-derived section and both megablocks exhibit similar middleto upper-amphibolite-facies metamorphic grades that suggest they might represent parts of a single terrane. However, the mica schists in the lower basement-derived sequence and in the megablock xenoliths show differences in both mineralogy and whole-rock chemistry that suggest a more mafi c source for the xenoliths. Similarly, the mineralogy of the amphibolite in the lower basement-derived section and its association with calc-silicate rock suggest a sedimentary protolith, whereas the bulk-rock and mineral chemistry of the megablock amphibolite indicate an igneous protolith. The lower basement-derived granite also shows bulk chemical and mineralogical differences from the megablock gneissic and biotite granites. ?? 2009 The Geological Society of America.

Comparison of clast frequency and size in the resurge deposits at the Chesapeake Bay impact structure (Eyreville A and Langley cores): Clues to the resurge process

USGS Publications Warehouse

Ormo, J.; Sturkell, E.; Horton, J. Wright; Powars, D.S.; Edwards, L.E.

2009-01-01

Collapse and inward slumping of unconsolidated sedimentary strata expanded the Chesapeake Bay impact structure far beyond its central basement crater. During crater collapse, sediment-loaded water surged back to fill the crater. Here, we analyze clast frequency and granulometry of these resurge deposits in one core hole from the outermost part of the collapsed zone (i.e., Langley) as well as a core hole from the moat of the basement crater (i.e., Eyreville A). Comparisons of clast provenance and flow dynamics show that at both locations, there is a clear change in clast frequency and size between a lower unit, which we interpret to be dominated by slumped material, and an upper, water-transported unit, i.e., resurge deposit. The contribution of material to the resurge deposit was primarily controlled by stripping and erosion. This includes entrainment of fallback ejecta and sediments eroded from the surrounding seafloor, found to be dominant at Langley, and slumped material that covered the annular trough and basement crater, found to be dominant at Eyreville. Eyreville shows a higher content of crystalline clasts than Langley. There is equivocal evidence for an anti-resurge from a collapsing central water plume or, alternatively, a second resurge pulse, as well as a transition into oscillating resurge. The resurge material shows more of a debris-flow-like transport compared to resurge deposits at some other marine target craters, where the ratio of sediment to water has been relatively low. This result is likely a consequence of the combination of easily disaggregated host sediments and a relatively shallow target water depth. ?? 2009 The Geological Society of America.

Evaluation of effects of changes in canal management and precipitation patterns on salinity in Biscayne Bay, Florida, using an integrated surface-water/groundwater model

USGS Publications Warehouse

Lohmann, Melinda A.; Swain, Eric D.; Wang, John D.; Dixon, Joann

2012-01-01

Biscayne National Park, located in Biscayne Bay in southeast Florida, is one of the largest marine parks in the country and sustains a large natural marine fishery where numerous threatened and endangered species reproduce. In recent years, the bay has experienced hypersaline conditions (salinity greater than 35 practical salinity units) of increasing magnitude and duration. Hypersalinity events were particularly pronounced during April to August 2004 in nearshore areas along the southern and middle parts of the bay. Prolonged hypersaline conditions can cause degradation of water quality and permanent damage to, or loss of, brackish nursery habitats for multiple species of fish and crustaceans as well as damage to certain types of seagrasses that are not tolerant of extreme changes in salinity. To evaluate the factors that contribute to hypersalinity events and to test the effects of possible changes in precipitation patterns and canal flows into Biscayne Bay on salinity in the bay, the U.S. Geological Survey constructed a coupled surface-water/groundwater numerical flow model. The model is designed to account for freshwater flows into Biscayne Bay through the canal system, leakage of salty bay water into the underlying Biscayne aquifer, discharge of fresh and salty groundwater from the Biscayne aquifer into the bay, direct effects of precipitation on bay salinity, indirect effects of precipitation on recharge to the Biscayne aquifer, direct effects of evapotranspiration (ET) on bay salinity, indirect effects of ET on recharge to the Biscayne aquifer, and maintenance of mass balance of both water and solute. The model was constructed using the Flow and Transport in a Linked Overland/Aquifer Density Dependent System (FTLOADDS) simulator, version 3.3, which couples the two-dimensional, surface-water flow and solute-transport simulator SWIFT2D with the density-dependent, groundwater flow an solute-transport simulator SEAWAT. The model was calibrated by a trial-and-error method to fit observed groundwater heads, estimated base flow, and measured bay salinity and temperatures from 1996 to 2004, as well as the location of the freshwater-saltwater interface in the aquifer, by adjusting ET rate limiters, canal vertical hydraulic conductance, leakage rate coefficients (transition-layer thickness and hydraulic conductivity), Manning's n value, and delineation of rainfall zones. Although flow budget calculations indicate that precipitation, ET, and groundwater flux into the bay represent a small portion of the overall budget, these factors may be important in controlling salinity in some parts of the bay, for example the southern parts of the bay where the canal system is not extensively developed or controlled. The balance of precipitation and ET during the wet season generally results in a reduction of bay salinity, whereas the balance of precipitation and ET during the dry season generally results in an increase in bay salinity. During years when wet season precipitation is lower than average, for example less than 70 percent total precipitation for an average year, ET could outweigh precipitation over the bay for essentially the entire year. Hypersaline conditions are prone to occur near the end of the dry season because precipitation rates are generally lower, canal discharge rates (which are strongly correlated to precipitation rates) are also generally lower, and ET rates are higher than during the rest of the year. The hypersalinity event of 2004 followed several years of relatively low precipitation and correspondingly reduced canal structure releases and was unusually extensive, continuing into July. Thus, hypersalinity is ultimately the result of a cumulative deficit of precipitation. The model was used to test the effects of possible changes in canal flux and precipitation. Simulation results showed that by increasing, reducing, or modifying canal discharge rates, the effects on salinity in the bay were more pronounced in the northern part of the bay where there are more canals and canal-control structures. By doubling and halving precipitation, the effects on bay salinity were more pronounced in the southern part of the bay than in the northern part of the bay where there are fewer canals and canal-control structures. The model is designed to quantify factors that contribute to hypersaline conditions in Biscayne Bay and may be less appropriate for addressing other issues or examining conditions substantially different from those described in this report. Model results must be interpreted in light of model limitations, which include representation of the system and conceptual model, uncertainty in physical properties used to describe the system or processes, the scale and discretization of the system, and representation of the boundary conditions.

Microbial Community Structure in Relation to Water Quality in a Eutrophic Gulf of Mexico Estuary

EPA Science Inventory

Weeks Bay is a shallow, microtidal, eutrophic sub-estuary of Mobile Bay, AL. High watershed nutrient inputs to the estuary contribute to a eutrophic condition characterized by frequent summertime diel-cycling hypoxia and dissolved oxygen (DO) oversaturation. Spatial and seasonal ...

8. Center bay of the east elevation (Note project supervisor ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. Center bay of the east elevation (Note project supervisor Mary Ellen Strain and project historian James Jacobs discussing the extant house in reference to a 1758 drawing of the structure). - John Bartram House & Garden, House, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA

Postimpact heat conduction and compaction-driven fluid flow in the Chesapeake Bay impact structure based on downhole vitrinite reflectance data, ICDP-USGS Eyreville deep core holes and Cape Charles test holes

USGS Publications Warehouse

Malinconico, M.L.; Sanford, W.E.; Wright, Horton W.J.J.

2009-01-01

Vitrinite reflectance data from the International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville deep cores in the centralcrater moat of the Chesapeake Bay impact structure and the Cape Charles test holes on the central uplift show patterns of postimpact maximum-temperature distribution that result from a combination of conductive and advective heat flow. Within the crater-fill sediment-clast breccia sequence at Eyreville, an isoreflectance (-0.44% Ro) section (525-1096 m depth) is higher than modeled background coastal-plain maturity and shows a pattern typical of advective fluid flow. Below an intervening granite slab, a short interval of sediment-clast breccia (1371-1397 m) shows a sharp increase in reflectance (0.47%-0.91% Ro) caused by conductive heat from the underlying suevite (1397-1474 m). Refl ectance data in the uppermost suevite range from 1.2% to 2.1% Ro. However, heat conduction alone is not sufficient to affect the temperature of sediments more than 100 m above the suevite. Thermal modeling of the Eyreville suevite as a 390 ??C cooling sill-like hot rock layer supplemented by compaction- driven vertical fluid flow (0.046 m/a) of cooling suevitic fluids and deeper basement brines (120 ??C) upward through the sediment breccias closely reproduces the measured reflectance data. This scenario would also replace any marine water trapped in the crater fill with more saline brine, similar to that currently in the crater, and it would produce temperatures sufficient to kill microbes in sediment breccias within 450 m above the synimsuevite. A similar downhole maturity pattern is present in the sediment-clast breccia over the central uplift. High-reflectance (5%-9%) black shale and siltstone clasts in the suevite and sediment-clast breccia record a pre-impact (Paleozoic?) metamorphic event. Previously published maturity data in the annular trough indicate no thermal effect there from impact-related processes. ?? 2009 The Geological Society of America.

Petrography, mineralogy, and geochemistry of deep gravelly sands in the Eyreville B core, Chesapeake Bay impact structure

USGS Publications Warehouse

Bartosova, Katerina; Gier, Susanne; Horton, J. Wright; Koeberl, Christian; Mader, Dieter; Dypvik, Henning

2010-01-01

The ICDP–USGS Eyreville drill cores in the Chesapeake Bay impact structure reached a total depth of 1766 m and comprise (from the bottom upwards) basement-derived schists and granites/pegmatites, impact breccias, mostly poorly lithified gravelly sand and crystalline blocks, a granitic slab, sedimentary breccias, and postimpact sediments. The gravelly sand and crystalline block section forms an approximately 26 m thick interval that includes an amphibolite block and boulders of cataclastic gneiss and suevite. Three gravelly sands (basal, middle, and upper) are distinguished within this interval. The gravelly sands are poorly sorted, clast supported, and generally massive, but crude size-sorting and subtle, discontinuous layers occur locally. Quartz and K-feldspar are the main sand-size minerals and smectite and kaolinite are the principal clay minerals. Other mineral grains occur only in accessory amounts and lithic clasts are sparse (only a few vol%). The gravelly sands are silica rich (~80 wt% SiO2). Trends with depth include a slight decrease in SiO2 and slight increase in Fe2O3. The basal gravelly sand (below the cataclasite boulder) has a lower SiO2 content, less K-feldspar, and more mica than the higher sands, and it contains more lithic clasts and melt particles that are probably reworked from the underlying suevite. The middle gravelly sand (below the amphibolite block) is finer-grained, contains more abundant clay minerals, and displays more variable chemical compositions than upper gravelly sand (above the block). Our mineralogical and geochemical results suggest that the gravelly sands are avalanche deposits derived probably from the nonmarine Potomac Formation in the lower part of the target sediment layer, in contrast to polymict diamictons higher in the core that have been interpreted as ocean-resurge debris flows, which is in agreement with previous interpretations. The mineralogy and geochemistry of the gravelly sands are typical for a passive continental margin source. There is no discernible mixing with marine sediments (no glauconite or Paleogene marine microfossils noted) during the impact remobilization and redeposition. The unshocked amphibolite block and cataclasite boulder might have originated from the outer parts of the transient crater.

Assessment of the content, structure, and source of soil dissolved organic matter in the coastal wetlands of Jiaozhou Bay, China

NASA Astrophysics Data System (ADS)

Xi, Min; Zi, Yuanyuan; Wang, Qinggai; Wang, Sen; Cui, Guolu; Kong, Fanlong

2018-02-01

The contents and the spectral analysis of dissolved organic matter (DOM) in four typical wetlands, such as naked tidal, suaeda salsa, reed and spartina, were conducted to investigate the content, structure, and source of DOM in coastal wetland soil. The soil samples were obtained from Jiaozhou Bay in January, April, July, and October of 2014. Results showed that the DOM contents in soil of four typical wetland were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in horizontal direction, and decreased with the increase of soil depth on vertical section. In addition, the DOM contents changed with the seasons, in order of spring > summer > autumn > winter. The structural characteristics of DOM in Jiaozhou Bay wetland, such as aromaticity, hydrophobicity, molecular weight, polymerization degree of benzene ring carbon frame structure and so on were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in the horizontal direction. On the vertical direction, they showed a decreasing trend with the increase of soil depth. The results of three dimensional fluorescence spectra and fluorescence spectrum parameters (FI, HIX, and BIX) indicated that the DOM in Jiaozhou Bay was mainly derived from the biological activities. The contents and structure of DOM had certain relevance, but the contents and source as well as the structure and source of DOM had no significant correlation. The external pollution including domestic sewage, industrial wastewater, and aquaculture sewage affected the correlation among the content, structure and source of DOM by influencing the percentage of non-fluorescent substance in DOM and disturbing the determination of protein-like fluorescence.

Chitosan-decorated selenium nanoparticles as protein carriers to improve the in vivo half-life of the peptide therapeutic BAY 55-9837 for type 2 diabetes mellitus.

PubMed

Rao, Lei; Ma, Yi; Zhuang, Manjiao; Luo, Tianjie; Wang, Yayu; Hong, An

2014-01-01

As a potential protein therapeutic for type 2 diabetes mellitus (T2DM), BAY 55-9837 is limited by poor stability and a very short half-life in vivo. The purpose of this study was to construct a novel nanostructured biomaterial by conjugating BAY 55-9837 to chitosan-decorated selenium nanoparticles (CS-SeNPs) to prolong the in vivo half-life of BAY 55-9837 by reducing its renal clearance rate. BAY 55-9837-loaded CS-SeNPs (BAY-CS-SeNPs) were prepared, and their surface morphology, particle size, zeta potential, and structure were characterized. The stability, protein-loading rate, and in vitro release of BAY 55-9837 from CS-SeNPs were also quantified. Additionally, a sensitive high-performance liquid chromatography (HPLC) assay was developed for the quantification of BAY 55-9837 in mouse plasma. Thereafter, mice were injected via the tail vein with either BAY 55-9837 or BAY-CS-SeNPs, and the plasma concentration of BAY 55-9837 was determined via our validated HPLC method at different time intervals postinjection. Relevant in vivo pharmacokinetic parameters (half-life, area under the curve from time 0 to last sampling point, observed clearance) were then calculated and analyzed. BAY-CS-SeNPs were successfully synthesized, with diameters of approximately 200 nm. BAY-CS-SeNPs displayed good stability with a high protein-loading rate, and the release process of BAY 55-9837 from the CS-SeNPs lasted for over 70 hours, with the cumulative release reaching 78.9%. Moreover, the conjugation of CS-SeNPs to BAY 55-9837 significantly reduced its renal clearance to a rate of 1.56 mL/h and extended its half-life to 20.81 hours. In summary, our work provides a simple method for reducing the renal clearance rate and extending the half-life of BAY 55-9837 in vivo by utilizing CS-SeNPs as nanocarriers.

Radioisotopic data of sediment collected in Mobile and Bon Secour Bays, Alabama

USGS Publications Warehouse

Marot, Marci E.; Smith, Christopher G.

2012-01-01

The focus of this study was to determine the extent of natural and (or) anthropogenic impacts on the sedimentary records of Mobile and Bon Secour Bays, Alabama during the last 150 years. These bays are unique in that anthropogenic activities are generally widespread and span both the eastern and western shorelines. However, there is a clear distinction in the types of human development and infrastructure between the western and eastern shorelines. These activities and the differences in land-use and -change influence the overall supply and remobilization of sediment to and within the bay. These factors could subsequently threaten the health and integrity of these environments and their ability to mitigate against long-term processes associated with climate change. In an attempt to characterize long-term accretion rates within the Mobile Bay Estuarine System (MBES), seven box cores were collected and analyzed for excess lead-210 (210Pbxs, the difference between total and supported 210Pb) and cesium-137 (137Cs) activities. The MBES receives sediment and water from the Alabama and Tombigbee River watersheds, which converge into the Mobile-Tensaw River (MTR) system just prior to discharging into Mobile Bay. Riverine discharge from the MTR system to the bay is second only to the Mississippi River discharge to the Gulf of Mexico for the conterminous United States.

Impacts of land cover changes on hurricane storm surge in the lower Chesapeake Bay

NASA Astrophysics Data System (ADS)

Denton, M.; Lawler, S.; Ferreira, C.

2013-12-01

The Chesapeake Bay is the largest estuary in the United States with more than 150 rivers draining into the bay's tidal wetlands. Coastal wetlands and vegetation play an important role in shaping the hydrodynamics of storm surge events by retaining water and slowing the propagation of storm surge. In this way coastal wetlands act as a natural barrier to inland flooding, particularly against less intense storms. Threats to wetlands come from both land development (residential or commercial/industrial) and sea level rise. The lower region of the Chesapeake Bay near its outlet is especially vulnerable to flooding from Atlantic storm surge brought in by hurricanes, tropical storms and nor'easters (e.g., hurricanes Isabel [2003] and Sandy [2012]). This region is also intensely developed with nearly 1.7 million residents within the greater Hampton Roads metropolitan area. Anthropogenic changes to land cover in the lower bay can directly impact basin drainage and storm surge propagation with impacts reaching beyond the immediate coastal zone to affect flooding in inland areas. While construction of seawall barriers around population centers may provide storm surge protection to a specifically defined area, these barriers deflect storm surge rather than attenuate it, underscoring the importance of wetlands. To analyze these impacts a framework was developed combining numerical simulations with a detailed hydrodynamic characterization of flow through coastal wetland areas. Storm surges were calculated using a hydrodynamic model (ADCIRC) coupled to a wave model (SWAN) forced by an asymmetric hurricane vortex model using the FEMA region 3 unstructured mesh (2.3 million nodes) under a High Performance Computing (HPC) environment. Multiple model simulations were performed using historical hurricanes data and hypothetical storms to compare the predicted storm surge inundation with various levels of wetland reduction and/or beach hardening. These data were combined and overlaid with a geospatial inventory of critical infrastructure assets to evaluate the potential for storm damage associated with each level of wetland reduction. This poster will present quantitative analyses of the benefits and losses regarding storm surge inundation and damage from land cover changes in the study region.

Evaluation of comprehensive environmental effect about coastal zone development activities in Liaoning Province and management advice.

PubMed

Wang, Wei-Wei; Cai, Yue-Yin; Sun, Yong-Guang; Ma, Hong-Wei

2015-07-01

Using spatial analysis function of Arcgis software, the present study investigated the building environment impact evaluation index system of coastal development in Liaoning Province. The factors of it included of current state of environmental quality, environmental impact of marine development and marine environmental disaster. Weighted factor analysis and comprehensive index method were utilized. At the end, comprehensive environment effect of coastal development in Liaoning Province were evaluated successfully. The result showed that the environmental effect of development activity were most serious, along the Zhao Jiatun coast in north of Zhimao bay and coast of Mianhua island in Dalian bay.

Forecasting system predicts presence of sea nettles in Chesapeake Bay

NASA Astrophysics Data System (ADS)

Brown, Christopher W.; Hood, Raleigh R.; Li, Zhen; Decker, Mary Beth; Gross, Thomas F.; Purcell, Jennifer E.; Wang, Harry V.

Outbreaks of noxious biota, which occur in both aquatic and terrestrial systems, can have considerable negative economic impacts. For example, an increasing frequency of harmful algal blooms worldwide has negatively affected the tourism industry in many regions. Such impacts could be mitigated if the conditions that give rise to these outbreaks were known and could be monitored. Recent advances in technology and communications allow us to continuously measure and model many environmental factors that are responsible for outbreaks of certain noxious organisms. A new prototype ecological forecasting system predicts the likelihood of occurrence of the sea nettle (Chrysaora quinquecirrha), a stinging jellyfish, in the Chesapeake Bay.

Early Holocene turnover, followed by stability, in a Caribbean lizard assemblage

NASA Astrophysics Data System (ADS)

Kemp, Melissa E.; Hadly, Elizabeth A.

2016-03-01

Understanding how communities are impacted by environmental perturbations is integral for addressing the ongoing biodiversity crisis that impacts ecosystems worldwide. The fossil record serves as a window into ancient interactions and the responses of communities to past perturbations. Here, we re-examine paleontological data from Katouche Bay, Anguilla, a Holocene site in the Lesser Antilles. We reveal that the site was more diverse than previously indicated, with long-term, continuous records of three genera of extant lizards (Anolis, Ameiva, and Thecadactylus), and the early Holocene presence of Leiocephalus, a large ground-dwelling lizard that has since been completely extirpated from the Lesser Antilles. The disappearance of Leiocephalus from Katouche Bay resulted in high turnover, decreased evenness, and decreased species richness-a trend that continues to the present day. Our body size reconstructions for the most abundant genus, Anolis, are consistent with the presence of only one species, Anolis cf. gingivinus, at Katouche Bay throughout the Holocene, contrary to previously published studies. Additionally, we find no evidence of dwarfism in A. cf. gingivinus, which contrasts with a global study of contemporary insular lizards. Our data reveal that the impacts of diversity loss on lizard communities are long lasting and irreversible over millennia.

Mobile Bay turbidity plume study

NASA Technical Reports Server (NTRS)

Crozier, G. F.

1976-01-01

Laboratory and field transmissometer studies on the effect of suspended particulate material upon the appearance of water are reported. Quantitative correlations were developed between remotely sensed image density, optical sea truth data, and actual sediment load. Evaluation of satellite image sea truth data for an offshore plume projects contours of transmissivity for two different tidal phases. Data clearly demonstrate the speed of change and movement of the optical plume for water patterns associated with the mouth of Mobile bay in which relatively clear Gulf of Mexico water enters the bay on the eastern side. Data show that wind stress in excess of 15 knots has a marked impact in producing suspended sediment loads.

Control of trace element toxicity in Chesapeake Bay by dominant phytoplankton. Final report

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

Sanders, J.G.; Riedel, G.F.; Connell, D.B.

1992-02-01

Copper (Cu) and arsenic (As), but not chromium (Cr), underwent large changes in chemical form during the development and senescence of natural phytoplankton blooms. In general, the percentage of organically-associated Cu was lowest during periods of rapid cell growth and highest during periods of cell decline or periods of dominance by red tide-forming dinoflagellates, a pattern tied to periods of release of organic compounds during either bloom senescence or during unusual algal blooms. Chromium, in contrast, was unreactive. The end result of biological mediation of both As and Cu was to increase the proportion of the element present in amore » less toxic form, at least to phytoplankton, thus affecting the potential toxicity of either element to a natural ecosystem. The results of the project provide a framework for the construction of general predictive models of likely trace element behavior in productive ecosystems and provide a conceptual theory of how such toxic contaminants may affect ecosystem structure and food webs within Chesapeake Bay. Predictive models of ecosystem impact will require further experimentation with multi-trophic level food chains.« less

Protein Secondary Structure Prediction Using AutoEncoder Network and Bayes Classifier

NASA Astrophysics Data System (ADS)

Wang, Leilei; Cheng, Jinyong

2018-03-01

Protein secondary structure prediction is belong to bioinformatics,and it's important in research area. In this paper, we propose a new prediction way of protein using bayes classifier and autoEncoder network. Our experiments show some algorithms including the construction of the model, the classification of parameters and so on. The data set is a typical CB513 data set for protein. In terms of accuracy, the method is the cross validation based on the 3-fold. Then we can get the Q3 accuracy. Paper results illustrate that the autoencoder network improved the prediction accuracy of protein secondary structure.

Magnitude and Distribution of Flows into Northeastern Florida Bay

USGS Publications Warehouse

Patino, Eduardo; Hittle, Clinton D.

2000-01-01

Changes in water-management practices have been made to accommodate a large and rapidly growing urban population along the Atlantic Coast and to meet the demand for intensive agricultural activities. These changes have resulted in a highly managed hydrologic system consisting of numerous canals, levees, control structures, and pumping stations that have altered the hydrology of the Everglades and Florida Bay ecosystems. Over the past decade, Florida Bay has experienced sea-grass die-off and algal blooms, which are indicators of ecological change attributed primarily to the increase in salinity and nutrient content of bay waters. Because plans are to restore sheetflow in the Everglades wetlands to its natural state, water managers anticipate a change in the magnitude and timing of freshwater exiting the mainland through the creeks that cut through the embankment or as sheetflow into Florida Bay.

Impacts of petroleum development in the Arctic

USGS Publications Warehouse

S.B., Robertson

1989-01-01

In their article “Cumulative impacts of oil fields on northern Alaskan landscapes.” D. A. Walter et al. (1) document some direct and indirect impacts of petroleum development in the Arctic on selected portions of the Prudhoe Bay Oil field. While most of the kinds of impacts they discuss are valid points to consider in designing an arctic oil field, the magnitude of what they describe is not representative of the Prudhoe Bay field, in general, or of newer oil fields, such as Kuparuk to the west of Prudhoe. It is even less applicable in areas of higher topographic relief, such as the coastal plain of the Arctic National Wildlife Refuge (ANWR).Any development will cause an impact to the land. In the Arctic, as noted by Walker et al., gravel roads and pads have been built that are thick enough to support facilities while the thermal integrity of the underlying permafrost is maintained. Decision-makers must evaluate whether or not the gains of development are worth the impacts incurred. Accurate assessment of both direct and indirect impacts is essential.

Sedimentary Evidence for Land Use Change in the Narragansett Bay Watershed: Late Woodland period (~500 AD) to the present

NASA Astrophysics Data System (ADS)

Salacup, J. M.; Altabet, M. A.; Herbert, T.; Prell, W. L.

2012-12-01

In the U.S., the last ~300 years have been a period of progressive and widespread resource exploitation, ecosystem degradation, and habitat destruction. In southern New England, the European Colonists thrived on the spread of slave-based plantation farming, which peaked ~1750 in RI. They produced commodities such as livestock, apples, onions, flax, and dairy. Trees felled to produce the necessary pasture- and farm-land were quickly used as lumber for boards, planks, timber, and barrels. In 1793, Slater Mill, located on the Blackstone River at the head of Narragansett Bay, was the first mill in the U.S to spin yarn using water power, making it the birthplace of the U.S Industrial Revolution. The ensuing urbanization drove the human population of the watershed up from ~50,000 in 1790 to more than 2 million by the year 2000. More recently, the Bay has experienced episodic hypoxic events [1]. These events correlate well with spatial and temporal patterns of nutrients and productivity [2] suggesting that human-induced increases in nutrient nitrogen and phosphorus are responsible for eutrophication-induced oxygen depletion [3]. However, these post-Colonial land use changes have yet to be characterized within the longer context of Native American land use practices, mainly due to the lack of historical records for the period. Additionally, the impact of this ecosystem disturbance on the Bay has not been fully described. Here we present results based on sedimentary profiles of biomarkers diagnostic for soil delivery to marine systems, branched glycerol dialykl glycerol tetraethers, and pollen for disturbance taxa, that suggest land use change began in the Bay's watershed 300 years before European contact. This contradicts long standing ideas regarding the land use practices of local tribes but agrees with new archaeological findings suggesting large semi-permanent settlements and widespread horticulture of maize may have been the norm at this time. We also show results of pollen, nitrogen isotopes, and foraminiferal abundance (proxies for land disturbance, nutrient sources, and ecosystem productivity, respectively) implying the large domestic animal population housed on the plantations were a new source of nitrogen to the Bay. This nutrient input may have led to an increase in the Bay's primary productivity, which may have decreased or stabilized as plantations became less important. Lastly, these same proxies show that the industrialization and urbanization of the Bay's watershed added additional nutrients, further stimulating the Bay's productivity. 1. Codiga, D.L., et al., Narragansett Bay Hypoxic Event Characteristics Based on Fixed-Site Monitoring Network Time Series: Intermittency, Geographic Distribution, Spatial Synchronicity, and Interannual Variablity. Estuaries and Coasts, 2009. 32: p. 621-641. 2. Oviatt, C.A., Impacts of Nutrients on Narragansett Bay Productivity: A Gradient Approach, in Science for Ecosystem-based Management, Narragansett Bay in the 21st Century, A. Desbonnet, Editor 2008, Springer: New York. p. 523-543. 3. Nixon, S.W., et al., Nitrogen and Phosphorus Inputs to Narragansett Bay: Past, Present, and Future, in Science for Ecosystem-based Management: Narragansett Bay in the 21st Century, A. Desbonnet and B.A. Costa-Pierce, Editors. 2008, Springer: New York, NY. p. 101-175.

A FIVE YEAR RECORD OF PHYTOPLANKTON PIGMENT PATTERNS IN ESCAMBIA/PENSACOLA BAY, FL

EPA Science Inventory

Phytoplankton pigments were monitored quarterly at over 50 stations in Escambia/Pensacola Bay System (Pensacola, FL) from spring of 1996 to fall 2000. HPLC accessory pigments were used to analyze the phytoplankton community structure. HPLC data suggest a dominance of blue-green a...

EVALUATING THE INTEGRITY OF SALT MARSHES IN NARRAGANSETT BAY SUBESTUARIES USING A WATESHED APPROACH

EPA Science Inventory

A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay was used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh to pro...

Linking Decisions to Stakeholder Values in the Guanica Bay Watershed, Puerto Rico

EPA Science Inventory

This presentation lays the foundation for the session by introducing the Structured Decision-Making (SDM) approach that is being used by the Environmental Protection Agency (EPA) in the Guánica Bay watershed of southwestern Puerto Rico. EPA is working with other agencies i...

EFFECTS OF DDT SEDIMENT-CONTAMINATION ON MACROFAUNAL COMMUNITY STRUCTURE AND COMPOSITION IN SAN FRANCISCO BAY

EPA Science Inventory

The objectives of this study were to determine the effects of sediment contamination on the benthic macrofauna and to predict macrofaunal changes following remediation at a Superfund (uncontrolled hazardous waste) site in San Francisco Bay, CA, USA. DDT and its metabolites (sumDD...

Empirical Bayes estimation of proportions with application to cowbird parasitism rates

USGS Publications Warehouse

Link, W.A.; Hahn, D.C.

1996-01-01

Bayesian models provide a structure for studying collections of parameters such as are considered in the investigation of communities, ecosystems, and landscapes. This structure allows for improved estimation of individual parameters, by considering them in the context of a group of related parameters. Individual estimates are differentially adjusted toward an overall mean, with the magnitude of their adjustment based on their precision. Consequently, Bayesian estimation allows for a more credible identification of extreme values in a collection of estimates. Bayesian models regard individual parameters as values sampled from a specified probability distribution, called a prior. The requirement that the prior be known is often regarded as an unattractive feature of Bayesian analysis and may be the reason why Bayesian analyses are not frequently applied in ecological studies. Empirical Bayes methods provide an alternative approach that incorporates the structural advantages of Bayesian models while requiring a less stringent specification of prior knowledge. Rather than requiring that the prior distribution be known, empirical Bayes methods require only that it be in a certain family of distributions, indexed by hyperparameters that can be estimated from the available data. This structure is of interest per se, in addition to its value in allowing for improved estimation of individual parameters; for example, hypotheses regarding the existence of distinct subgroups in a collection of parameters can be considered under the empirical Bayes framework by allowing the hyperparameters to vary among subgroups. Though empirical Bayes methods have been applied in a variety of contexts, they have received little attention in the ecological literature. We describe the empirical Bayes approach in application to estimation of proportions, using data obtained in a community-wide study of cowbird parasitism rates for illustration. Since observed proportions based on small sample sizes are heavily adjusted toward the mean, extreme values among empirical Bayes estimates identify those species for which there is the greatest evidence of extreme parasitism rates. Applying a subgroup analysis to our data on cowbird parasitism rates, we conclude that parasitism rates for Neotropical Migrants as a group are no greater than those of Resident/Short-distance Migrant species in this forest community. Our data and analyses demonstrate that the parasitism rates for certain Neotropical Migrant species are remarkably low (Wood Thrush and Rose-breasted Grosbeak) while those for others are remarkably high (Ovenbird and Red-eyed Vireo).

The landscape pattern characteristics of coastal wetlands in Jiaozhou Bay under the impact of human activities.

PubMed

Gu, Dongqi; Zhang, Yuanzhi; Fu, Jun; Zhang, Xuliang

2007-01-01

In this study, we interpreted coastal wetland types from an ASTER satellite image in 2002, and then compared the results with the land-use status of coastal wetlands in 1952 to determine the wetland loss and degradation around Jiaozhou Bay. Seven types of wetland landscape were classified, namely: shallow open water, inter-tidal flats, estuarine water, brackish marshes, salt ponds, fishery ponds and ports. Several landscape pattern indices were analysed: the results indicate that the coastal wetlands have been seriously degraded. More and more natural wetlands have been transformed into artificial wetlands, which covered about 33.7% of the total wetlands in 2002. In addition, we used a defined model to assess the impacts of human activities on coastal wetlands. The results obtained show that the coastal wetlands of Jiaozhou Bay have suffered severe human disturbance. Effective coastal management and control is therefore needed to solve the issues of the coastal wetland loss and degradation existing in this area.

Separation of wind's influence on harmful cyanobacterial blooms.

PubMed

Wang, Hua; Zhang, Zhizhang; Liang, Dongfang; du, Hanbei; Pang, Yong; Hu, Kaimin; Wang, Jianjian

2016-07-01

Wind is an important physical factor involved in Harmful Cyanobacterial blooms (CyanoHABs). Its integrated influence was separated to three components: (a) Direct Disturbance Impact (DDI) on cyanbacterial proliferation, (b) Indirect Nutrient Impact (INI) by sediment release and (c) Direct Transportation Impact (DTI) by both gentle wind-induced surface drift and wave-generated Stokes drift. By the combination of field investigation, laboratory experiment and numerical simulation their individual contributions to the severe bloom event in May 2007 in Meiliang Bay, Lake Taihu, was explored. Wind synthetically made 10.5 percent promotion to the bloom on May 28, 2007, but the impact varied with locations. DTI was featured with the strongest contribution of wind's impacts on CyanoHABs, while INI stood at the lowest level and DDI played an intermediate role. From the point of whole Meiliang Bay, the influencing weights of DTI, DDI and INI were approximately 48.55%, 32.30% and 19.15% respectively. DTI exerted the higher promotion in the regions of middle-east (ME), southwest (SW) and southeast (SE), and its actual contribution rate on CyanoHABs ranged from 6.41% to 7.46%. Due to the background nutrient load, INI was characterized by a tiny effect with the contribution rate being 2.18% on average. From the south bay to the north, DDI was detected with a decreasing tendency, with the practical contribution rate generally falling from 4.13% to 2.7%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Marine magnetic survey and onshore gravity and magnetic survey, San Pablo Bay, northern California

USGS Publications Warehouse

Ponce, David A.; Denton, Kevin M.; Watt, Janet T.

2016-09-12

IntroductionFrom November 2011 to August 2015, the U.S. Geological Survey (USGS) collected more than 1,000 line-kilometers (length of lines surveyed in kilometers) of marine magnetic data on San Pablo Bay, 98 onshore gravity stations, and over 27 line-kilometers of ground magnetic data in northern California. Combined magnetic and gravity investigations were undertaken to study subsurface geologic structures as an aid in understanding the geologic framework and earthquake hazard potential in the San Francisco Bay Area. Furthermore, marine magnetic data illuminate local subsurface geologic features in the shallow crust beneath San Pablo Bay where geologic exposure is absent.Magnetic and gravity methods, which reflect contrasting physical properties of the subsurface, are ideal for studying San Pablo Bay. Exposed rock units surrounding San Pablo Bay consist mainly of Jurassic Coast Range ophiolite, Great Valley sequence, Franciscan Complex rocks, Miocene sedimentary rocks, and unconsolidated alluvium (Graymer and others, 2006). The contrasting magnetic and density properties of these rocks enable us to map their subsurface extent.

Short Term Sediment Exchange Between Marshes and Bays Using Beryllium-7 as a Tracer, Fourleague Bay, Louisiana.

NASA Astrophysics Data System (ADS)

Restreppo, G. A.; Bentley, S. J.; Xu, K.; Wang, J.

2016-12-01

Modern delta models focus on the availability and exchange of coarse sediment as one of the major factors of deltaic growth or decay. Fine-grained sediment exchange within a river's delta is relatively poorly understood, as is the impact that this exchange has on land building and land loss. To better understand the dynamics of fine grain sediment exchange between river mouth, adjacent bays, and marshland, sediment cores from Fourleague Bay, LA, were collected and analyzed for 7Be, a naturally occurring radioisotope that serves as a marker for recently deposited sediment. Time-series push cores were collected every two months at ten sites, five located across a longitudinal transect in the middle bay and five located along adjacent marshes, from May 2015 to May 2016. All sites fall within 11 to 28 km of the Atchafalaya Delta, along a gradient extending towards the open ocean. Cores were extruded in 2 cm intervals, dried, ground, and analyzed via gamma spectrometry for the presence of 7Be. Inventories of 7Be were then calculated and used to determine bimonthly sedimentation rates over the course twelve months. Sediment deposition on the bay floor and marsh surface were then compared to Atchafalaya River discharge, wind speed and direction, and wave action. Preliminary results indicate patterns of initial fluvial sediment transfer from river to bay floor, then bay floor to marsh surface, with decreasing fluvial influence towards the open ocean. Sediment transport from bay to marsh appears to be coupled with meteorological forcing that induces bay-floor sediment resuspension and the flooding of marsh surfaces. This indirect mechanism of fluvial sediment supply to wetland surfaces may extend the region of influence for sediment delivery from man-made river-sediment diversions.

Interferometric Sidescan Bathymetry, Sediment and Foraminiferal Analyses; a New Look at Tomales Bay, California

USGS Publications Warehouse

Anima, Roberto J.; Chin, John L.; Finlayson, David P.; McGann, Mary; Wong, Florence L.

2008-01-01

The United States Geological Survey (USGS) in collaboration with Point Reyes National Sea Shore (PRNS), and the Tomales Bay Watershed Council [http://www.tomalesbaywatershed.org/] has completed a detailed bathymetric survey, and sediment and foraminiferal analyses of the floor of Tomales Bay, California. The study goals are to detail the submarine morphology, the sediment distribution, sedimentary features, and distribution of foraminifera to provide a framework for future studies. The USGS collected swath bathymetric data with a SEA SWATHplus interferometric sidescan sonar system (2004, 2005) and an echo sounder system (2006). The data were processed into continuous mosaic images that show bathymetric detail of the bay floor with 0.2-m vertical and 4.0-m horizontal resolution. Acoustic backscatter data from the 2004 and 2005 surveys were processed into 2-m resolution grids. In addition, 27 sediment samples were collected from various parts of the bay for grain size analyses and a comprehensive study of the distribution of foraminifera in Tomales Bay. The foraminiferal analysis determined that the invasive foraminifera Trochammina hadai from Japan was present in Tomales Bay. The project was conducted in response to a request from the National Park Service, and the Tomales Bay Watershed Council who voiced a need to look at the environmental impacts of human input to the surrounding watersheds that ultimately flow into the bay. The mapping, sediment, and foraminiferal data establish a baseline survey for future comparisons of possible geologic and anthropogenic changes that might occur due to changes in land use or development in the surrounding watershed. These data may also aid in determining the possible pathways of pollutants entering the bay from the surrounding watersheds.

The unnatural history of Kāne‘ohe Bay: coral reef resilience in the face of centuries of anthropogenic impacts

PubMed Central

Jokiel, Paul L.; Toonen, Robert J.

2015-01-01

Kāneʻohe Bay, which is located on the on the NE coast of Oʻahu, Hawaiʻi, represents one of the most intensively studied estuarine coral reef ecosystems in the world. Despite a long history of anthropogenic disturbance, from early settlement to post European contact, the coral reef ecosystem of Kāneʻohe Bay appears to be in better condition in comparison to other reefs around the world. The island of Moku o Loʻe (Coconut Island) in the southern region of the bay became home to the Hawaiʻi Institute of Marine Biology in 1947, where researchers have since documented the various aspects of the unique physical, chemical, and biological features of this coral reef ecosystem. The first human contact by voyaging Polynesians occurred at least 700 years ago. By A.D. 1250 Polynesians voyagers had settled inhabitable islands in the region which led to development of an intensive agricultural, fish pond and ocean resource system that supported a large human population. Anthropogenic disturbance initially involved clearing of land for agriculture, intentional or accidental introduction of alien species, modification of streams to supply water for taro culture, and construction of massive shoreline fish pond enclosures and extensive terraces in the valleys that were used for taro culture. The arrival by the first Europeans in 1778 led to further introductions of plants and animals that radically changed the landscape. Subsequent development of a plantation agricultural system led to increased human immigration, population growth and an end to traditional land and water management practices. The reefs were devastated by extensive dredge and fill operations as well as rapid growth of human population, which led to extensive urbanization of the watershed. By the 1960’s the bay was severely impacted by increased sewage discharge along with increased sedimentation due to improper grading practices and stream channelization, resulting in extensive loss of coral cover. The reefs of Kāneʻohe Bay developed under estuarine conditions and thus have been subjected to multiple natural stresses. These include storm floods, a more extreme temperature range than more oceanic reefs, high rates of sedimentation, and exposure at extreme low tides. Deposition and degradation of organic materials carried into the bay from the watershed results in low pH conditions such that according to some ocean acidification projections the rich coral reefs in the bay should not exist. Increased global temperature due to anthropogenic fossil fuel emmisions is now impacting these reefs with the first “bleaching event” in 1996 and a second more severe event in 2014. The reefs of Kāneʻohe Bay have developed and persist under rather severe natural and anthropogenic perturbations. To date, these reefs have proved to be very resilient once the stressor has been removed. A major question remains to be answered concerning the limits of Kāneʻohe Bay reef resilience in the face of global climate change. PMID:26020007

The influence of bottom boundary layer hydrodynamics on sediment focusing in a contaminated bay.

PubMed

Graham, Neil D; Bouffard, Damien; Loizeau, Jean-Luc

2016-12-01

Understanding the dynamics and fate of particle bound contaminants is important for mitigating potential environmental, economic and health impacts linked to their presence. Vidy Bay, Lake Geneva (Switzerland), is contaminated due to the outfall and overflow from the wastewater treatment plant of the City of Lausanne. This study was designed to investigate the fate of particle-bound contaminants with the goal of providing a more complete picture of contaminant pathways within the bay and their potential spread to the main basin. This goal was achieved by investigating the sediment transport dynamics, using sediment traps and radionuclide tracers, and ascertaining how local bottom-boundary hydrodynamic conditions (temperature, turbidity, current velocity and direction) influence these dynamics. Results of the study indicated that sedimentation rates and lateral advections increased vertically with proximity to the lakebed and laterally with proximity to shore, indicating the presence of sediment focusing in the bay. Hydrodynamic measurements showed the persistent influence of a gyre within the bay, extending down to the lake bed, while just outside of the bay circulation was influenced by the seasonal patterns of the main basin. Calculated mean displacement distances in the bay indicated that suspended particles can travel ∼3 km per month, which is 1.7 times the width of the Vidy Bay gyre. This results in a residence time of approximately 21 days for suspended particles, which is much greater than previously modelled results. The calculated mobility Shield parameter never exceeded the threshold shear stress needed for resuspension in deeper parts of the bay. In such, increased lateral advections to the bay are not likely due to local resuspension but rather external particle sources, such as main basin or shallow, littoral resuspensions. These external sources coupled with an increased residence time and decreased current velocity within the bay are the precipitating factors in sediment focusing. While the spread of contaminants from the bay may occur through the transport of fine suspended sediments in shallower zones of the bay (<60 m) by longshore littoral currents, results suggest that particle-bound contaminants are likely to remain within the bay.

Agricultural and urban pollution

NASA Technical Reports Server (NTRS)

Brehmer, M. L.

1972-01-01

The degradation produced by the introduction of agricultural and urban wastes into estuarine systems, with emphasis on the Chesapeake Bay area, is discussed. The subjects presented are: (1) effects of sediment loading and (2) organic and nutrient loading problems. The impact of high turbidity on the biological life of the bay is analyzed. The sources of nutrients which produce over-enrichment of the waters and the subsequent production of phytoplankton are examined.

Ports and Waterways Safety Assessment Workshop Report for Passamaquoddy Bay, ME

DTIC Science & Technology

2006-10-04

more impacted/conducted than commercial and recreational fishing)…clammers operate in the area. Sea cucumbers , herring. • Recreational fishing...discussed. The transit route from sea to Eastport consists of passage through the Bay of Fundy to Head Harbor Passage and Friar Roads. Vessels calling...more enforcement of regulations, conduct more at sea boarding. 1 Not Defined • Require mandatory or standardized equipment 1 Not Defined • Provide

Linking human impacts within an estuary to ebb-tidal delta evolution

USGS Publications Warehouse

Dallas, Kate L.; Barnard, Patrick L.

2009-01-01

San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.

An Approach to Understanding Complex Socio-Economic Impacts and Responses to Climate Disruption in the Chesapeake Bay Region

NASA Astrophysics Data System (ADS)

Schaefer, R. K.; Nix, M.; Ihde, A. G.; Paxton, L. J.; Weiss, M.; Simpkins, S.; Fountain, G. H.; APl GAIA Team

2011-12-01

In this paper we describe the application of a proven methodology for modeling the complex social and economic interactions of a system under stress to the regional issues that are tied to global climate disruption. Under the auspices of the GAIA project (http://gaia.jhuapl.edu), we have investigated simulating the complex interplay between climate, politics, society, industry, and the environment in the Chesapeake Bay Watershed and associated geographic areas of Maryland, Virginia, and Pennsylvania. This Chesapeake Bay simulation draws on interrelated geophysical and climate models to support decision-making analysis about the Bay. In addition to physical models, however, human activity is also incorporated via input and output calculations. For example, policy implications are modeled in relation to business activities surrounding fishing, farming, industry and manufacturing, land development, and tourism. This approach fosters collaboration among subject matter experts to advance a more complete understanding of the regional impacts of climate change. Simulated interactive competition, in which teams of experts are assigned conflicting objectives in a controlled environment, allow for subject exploration which avoids trivial solutions that neglect the possible responses of affected parties. Results include improved planning, the anticipation of areas of conflict or high risk, and the increased likelihood of developing mutually acceptable solutions.

Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA

USGS Publications Warehouse

Hui, C.A.; Rudnick, D.; Williams, E.

2005-01-01

Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators. Hepatopancreas concentrations of mercury decline with crab size, which may have important consequences for bio-magnification in food webs. ?? 2004 Elsevier Ltd. All rights reserved.

Orion Crew Module Structural Test Article Lift & Uncrating

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the cover has been removed from the container holding the Orion crew module structural test article (STA). The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Unbagging

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, Lockheed Martin technicians remove the protective covering from the Orion crew module structural test article (STA). The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Unbagging

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the cover has been removed from the container holding the Orion crew module structural test article (STA). The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Docking system for spacecraft

NASA Technical Reports Server (NTRS)

Kahn, Jon B. (Inventor)

1988-01-01

A mechanism is disclosed for the docking of a spacecraft to a space station where a connection for transfer of personnel and equipment is desired. The invention comprises an active docking structure on a spacecraft and a passive docking structure on the station. The passive structure includes a docking ring mounted on a tunnel structure fixed to the space station. The active structure includes a docking ring carried by an actuator-attenuator devices, each attached at one end to the ring and at its other end in the spacecraft payload bay. The devices respond to command signals for moving the docking ring between a stowed position in the spacecraft to a deployed position suitable for engagement with the docking ring. The devices comprise means responsive to signals of sensed loadings to absorb impact energy and retraction means for drawing the coupled spacecraft and station into final docked configuration and moving the tunnel structure to a berthed position in the spacecraft. Latches couple the spacecraft and space station upon contact of the docking rings and latches establish a structural tie between the spacecraft when retracted.

Modeled Sea Level Rise Impacts on Coastal Ecosystems at Six Major Estuaries on Florida’s Gulf Coast: Implications for Adaptation Planning

PubMed Central

Birch, Anne P.; Brenner, Jorge; Gordon, Doria R.

2015-01-01

The Sea Level Affecting Marshes Model (SLAMM) was applied at six major estuaries along Florida’s Gulf Coast (Pensacola Bay, St. Andrews/Choctawhatchee Bays, Apalachicola Bay, Southern Big Bend, Tampa Bay and Charlotte Harbor) to provide quantitative and spatial information on how coastal ecosystems may change with sea level rise (SLR) and to identify how this information can be used to inform adaption planning. High resolution LiDAR-derived elevation data was utilized under three SLR scenarios: 0.7 m, 1 m and 2 m through the year 2100 and uncertainty analyses were conducted on selected input parameters at three sites. Results indicate that the extent, spatial orientation and relative composition of coastal ecosystems at the study areas may substantially change with SLR. Under the 1 m SLR scenario, total predicted impacts for all study areas indicate that coastal forest (-69,308 ha; -18%), undeveloped dry land (-28,444 ha; -2%) and tidal flat (-25,556 ha; -47%) will likely face the greatest loss in cover by the year 2100. The largest potential gains in cover were predicted for saltmarsh (+32,922 ha; +88%), transitional saltmarsh (+23,645 ha; na) and mangrove forest (+12,583 ha; +40%). The Charlotte Harbor and Tampa Bay study areas were predicted to experience the greatest net loss in coastal wetlands The uncertainty analyses revealed low to moderate changes in results when some numerical SLAMM input parameters were varied highlighting the value of collecting long-term sedimentation, accretion and erosion data to improve SLAMM precision. The changes predicted by SLAMM will affect exposure of adjacent human communities to coastal hazards and ecosystem functions potentially resulting in impacts to property values, infrastructure investment and insurance rates. The results and process presented here can be used as a guide for communities vulnerable to SLR to identify and prioritize adaptation strategies that slow and/or accommodate the changes underway. PMID:26207914

Modeled Sea Level Rise Impacts on Coastal Ecosystems at Six Major Estuaries on Florida's Gulf Coast: Implications for Adaptation Planning.

PubMed

Geselbracht, Laura L; Freeman, Kathleen; Birch, Anne P; Brenner, Jorge; Gordon, Doria R

2015-01-01

The Sea Level Affecting Marshes Model (SLAMM) was applied at six major estuaries along Florida's Gulf Coast (Pensacola Bay, St. Andrews/Choctawhatchee Bays, Apalachicola Bay, Southern Big Bend, Tampa Bay and Charlotte Harbor) to provide quantitative and spatial information on how coastal ecosystems may change with sea level rise (SLR) and to identify how this information can be used to inform adaption planning. High resolution LiDAR-derived elevation data was utilized under three SLR scenarios: 0.7 m, 1 m and 2 m through the year 2100 and uncertainty analyses were conducted on selected input parameters at three sites. Results indicate that the extent, spatial orientation and relative composition of coastal ecosystems at the study areas may substantially change with SLR. Under the 1 m SLR scenario, total predicted impacts for all study areas indicate that coastal forest (-69,308 ha; -18%), undeveloped dry land (-28,444 ha; -2%) and tidal flat (-25,556 ha; -47%) will likely face the greatest loss in cover by the year 2100. The largest potential gains in cover were predicted for saltmarsh (+32,922 ha; +88%), transitional saltmarsh (+23,645 ha; na) and mangrove forest (+12,583 ha; +40%). The Charlotte Harbor and Tampa Bay study areas were predicted to experience the greatest net loss in coastal wetlands The uncertainty analyses revealed low to moderate changes in results when some numerical SLAMM input parameters were varied highlighting the value of collecting long-term sedimentation, accretion and erosion data to improve SLAMM precision. The changes predicted by SLAMM will affect exposure of adjacent human communities to coastal hazards and ecosystem functions potentially resulting in impacts to property values, infrastructure investment and insurance rates. The results and process presented here can be used as a guide for communities vulnerable to SLR to identify and prioritize adaptation strategies that slow and/or accommodate the changes underway.

Finite-frequency traveltime tomography of San Francisco Bay region crustal velocity structure

USGS Publications Warehouse

Pollitz, F.F.

2007-01-01

Seismic velocity structure of the San Francisco Bay region crust is derived using measurements of finite-frequency traveltimes. A total of 57 801 relative traveltimes are measured by cross-correlation over the frequency range 0.5-1.5 Hz. From these are derived 4862 'summary' traveltimes, which are used to derive 3-D P-wave velocity structure over a 341 ?? 140 km2 area from the surface to 25 km depth. The seismic tomography is based on sensitivity kernels calculated on a spherically symmetric reference model. Robust elements of the derived P-wave velocity structure are: a pronounced velocity contrast across the San Andreas fault in the south Bay region (west side faster); a moderate velocity contrast across the Hayward fault (west side faster); moderately low velocity crust around the Quien Sabe volcanic field and the Sacramento River delta; very low velocity crust around Lake Berryessa. These features are generally explicable with surface rock types being extrapolated to depth ???10 km in the upper crust. Generally high mid-lower crust velocity and high inferred Poisson's ratio suggest a mafic lower crust. ?? Journal compilation ?? 2007 RAS.

Development of the beliefs about yoga scale.

PubMed

Sohl, Stephanie J; Schnur, Julie B; Daly, Leslie; Suslov, Kathryn; Montgomery, Guy H

2011-01-01

Beliefs about yoga may influence participation in yoga and outcomes of yoga interventions. There is currently no scale appropriate for assessing these beliefs in the general U.S. population. This study took the first steps in developing and validating a Beliefs About Yoga Scale (BAYS) to assess beliefs about yoga that may influence people's engagement in yoga interventions. Items were generated based on previously published research about perceptions of yoga and reviewed by experts within the psychology and yoga communities. 426 adult participants were recruited from an urban medical center to respond to these items. The mean age was 40.7 (SD=13.5) years. Participants completed the BAYS and seven additional indicators of criterion-related validity. The BAYS demonstrated internal consistency (11 items; α=0.76) and three factors emerged: expected health benefits, expected discomfort, and expected social norms. The factor structure was confirmed: x2 (41, n=213)=72.06, p<.001; RMSEA=06, p=.23. Criterion-related validity was supported by positive associations of the BAYS with past experiences and future intentions related to yoga. This initial analysis of the BAYS demonstrated that it is an adequately reliable and valid measure of beliefs about yoga with a three-factor structure. However, the scale may need to be modified based on the population to which it is applied.

Bayes factors for testing inequality constrained hypotheses: Issues with prior specification.

PubMed

Mulder, Joris

2014-02-01

Several issues are discussed when testing inequality constrained hypotheses using a Bayesian approach. First, the complexity (or size) of the inequality constrained parameter spaces can be ignored. This is the case when using the posterior probability that the inequality constraints of a hypothesis hold, Bayes factors based on non-informative improper priors, and partial Bayes factors based on posterior priors. Second, the Bayes factor may not be invariant for linear one-to-one transformations of the data. This can be observed when using balanced priors which are centred on the boundary of the constrained parameter space with a diagonal covariance structure. Third, the information paradox can be observed. When testing inequality constrained hypotheses, the information paradox occurs when the Bayes factor of an inequality constrained hypothesis against its complement converges to a constant as the evidence for the first hypothesis accumulates while keeping the sample size fixed. This paradox occurs when using Zellner's g prior as a result of too much prior shrinkage. Therefore, two new methods are proposed that avoid these issues. First, partial Bayes factors are proposed based on transformed minimal training samples. These training samples result in posterior priors that are centred on the boundary of the constrained parameter space with the same covariance structure as in the sample. Second, a g prior approach is proposed by letting g go to infinity. This is possible because the Jeffreys-Lindley paradox is not an issue when testing inequality constrained hypotheses. A simulation study indicated that the Bayes factor based on this g prior approach converges fastest to the true inequality constrained hypothesis. © 2013 The British Psychological Society.

Assessing the ecological effects of human impacts on coral reefs in Bocas del Toro, Panama.

PubMed

Seemann, Janina; González, Cindy T; Carballo-Bolaños, Rodrigo; Berry, Kathryn; Heiss, Georg A; Struck, Ulrich; Leinfelder, Reinhold R

2014-03-01

Environmental and biological reef monitoring was conducted in Almirante Bay (Bahía Almirante) in Bocas del Toro, Panama, to assess impacts from anthropogenic developments. An integrated monitoring investigated how seasonal temperature stress, turbidity, eutrophication and physical impacts threatened reef health and biodiversity throughout the region. Environmental parameters such as total suspended solids [TSS], carbon isotopes (δ(13)C), C/N ratios, chlorophyll a, irradiance, secchi depth, size fractions of the sediments and isotope composition of dissolved inorganic carbon [DIC] of the water were measured throughout the years 2010 and 2011 and were analysed in order to identify different impact sources. Compared to data from Collin et al. (Smithsonian Contributions to the Marine Sciences 38:324-334, 2009) chlorophyll a has doubled at sites close to the city and the port Almirante (from 0.46-0.49 to 0.78-0.97 μg l(-1)) and suspension load increased, visible by a decrease in secchi depth values. Visibility decreased from 9-13 m down to 4 m at the bay inlet Boca del Drago, which is strongly exposed to river run off and dredging for the shipping traffic. Eutrophication and turbidity levels seemed to be the determining factor for the loss of hard coral diversity, most significant at chlorophyll a levels higher than 0.5 μg l(-1) and TSS levels higher than 4.7 mg l(-1). Hard coral cover within the bay has also declined, at some sites down to <10 % with extremely low diversities (7 hard coral species). The hard coral species Porites furcata dominated the reefs in highly impacted areas and showed a strong recovery after bleaching and a higher tolerance to turbidity and eutrophication compared to other hard coral species in the bay. Serious overfishing was detected in the region by a lack of adult and carnivorous fish species, such as grunts, snappers and groupers. Study sites less impacted by anthropogenic activities and/or those with local protection showed a higher hard coral cover and fish abundance; however, an overall loss of hard coral diversity was observed.

High resolution seismic reflection survey in the Gulf of Pozzuoli, Naples, Italy. An example of preliminary interpretation of seismic profiles.

NASA Astrophysics Data System (ADS)

D'Aniello, Elena; di Fiore, Vincenzo; Sacchi, Marco; Rapolla, Antonio

2010-05-01

During the cruise CAFE_07 - Leg 3 conducted in the Gulf of Naples and Pozzuoli in January 2008, on board of the R/V URANIA of the CNR it was carried out the acquisition of a grid of ca. 800 km of high-resolution multichannel reflection seismic profiles (Sacchi et al., 2009; Di Fiore et al., 2009). The aim of the cruise was the understanding of the stratigraphic-structural setting of the Pozzuoli Bay area, with specific reference to the major offshore volcanic features, such as Nisida Bank, Pentapalummo Bank, M.Dolce-Pampano Bank and Miseno Bank and others. The Gulf of Pozzuoli is placed in the Volcanic district of Campi Flegrei, an area of active volcanism located at North West of Naples city, along the Tyrrhenian margin, in an extensional collapsed area called Campanian Plain, filled by siliciclastic, epiclastic and volcaniclastic sediments, deposited during Late Pliocene and Quaternary. Several studies present in literature suggest a relation between volcanic system of Campi Flegrei and faults system; in particular, at the Gulf of Pozzuoli we can observe some volcanic banks and submarine volcanic edifices, as Pentapalummo, Nisida and Miseno Banks, are aligned along the NE-SW trending Magnaghi-Sebeto fault line, that separates the Bay of Naples into two sectors: the first, at NW of the Bay, characterized by volcanism activity and magnetic anomalies and the second, at SE of the bay, involved only by sedimentary activity, with the exceptions of the circular anomalies in the offshore of Torre del Greco city (Bruno et al., 2003; Secomandi et al., 2003); other volcanic hights are instead positioned along NW-SE structural discontinuities (Bruno, 2004). The magnetic and gravimetric analysis of the Bay of Naples confirms the tectonic control of the Campanian volcanism: we can observe a good correspondence of high magnetic anomalies with the main volcanic structures at the North-Western side of the bay, just the Gulf of Pozzuoli, where both NE-SW and NW-SE normal faults were recognized. The correspondence between magnetic structures, interpreted as volcanic bodies, and the faults NE-SW and NW-SE trending, supports the hypothesis that the magma rises along normal faults cutting the carbonate platform. We here present two significant seismic profiles: their interpretation reveals a complex stratigraphic and structural setting, dominated by the occurrence of volcanic bodies and siliciclastic depositional units, mostly deriving from the dismantling of the adjacent vents and volcaniclastic units. The results of this preliminary research include the recognition of volcanic features and structures not yet described in the literature that may represent a relevant contribute to the understanding of the Late Quaternary evolution of the Campi Flegrei area. References: Bruno P.P., Rapolla A., Di Fiore V., 2003. Structural setting of the Bay of Naples (Italy) seismic reflection data: implications for Campanian volcanism. Tectonophysics, 372, 193-213. Bruno P.P., 2004. Structure and evolution of the Bay of Pozzuoli (Italy) using marine seismic reflection data: implication for collapse of the Campi Flegrei caldera. Bull. Volcanol., 66, 342-355. Di Fiore V., D'Aniello E., Rapolla A., Sacchi M., Secomandi M., Spiess V., 2009. Multichannel seismic survey in coastal Campania area by two different resolution sources. EGU General Assembly 2009, vol.11. Sacchi M., Alessio G., Aquino I., Esposito E., Molisso F., Nappi R., Porfido S., Violante C., 2008. Risultati preliminari della campagna oceanografica CAFE_07 - Leg 3 nei Golfi di Napoli e Pozzuoli, Mar Tirreno Orientale. Quaderni di Geofisica, n. 64. Secomandi M., Paoletti V., Aiello G., Fedi M., Marsella E., Ruggieri S., D'Argenio B., Rapolla A., 2003. Analysis of the magnetic anomaly field of the volcanic district of the Bay of Naples, Italy. Marine Geophysical Researches. 24: 207-221.

Potential Inundation due to Rising Sea Levels in the San Francisco Bay Region

USGS Publications Warehouse

Knowles, Noah

2009-01-01

An increase in the rate of sea level rise is one of the primary impacts of projected global climate change. To assess potential inundation associated with a continued acceleration of sea level rise, the highest resolution elevation data available were assembled from various sources and mosaicked to cover the land surfaces of the San Francisco Bay region. Next, to quantify high water levels throughout the bay, a hydrodynamic model of the San Francisco Estuary was driven by a projection of hourly water levels at the Presidio. This projection was based on a combination of climate model outputs and empirical models and incorporates astronomical, storm surge, El Niño, and long-term sea level rise influences. Based on the resulting data, maps of areas vulnerable to inundation were produced, corresponding to specific amounts of sea level rise and recurrence intervals. These maps portray areas where inundation will likely be an increasing concern. In the North Bay, wetland survival and developed fill areas are at risk. In Central and South bays, a key feature is the bay-ward periphery of developed areas that would be newly vulnerable to inundation. Nearly all municipalities adjacent to South Bay face this risk to some degree. For the Bay as a whole, as early as 2050 under this scenario, the one-year peak event nearly equals the 100-year peak event in 2000. Maps of vulnerable areas are presented and some implications discussed.

Bat response to carolina bays and wetland restoration in the southeastern U.S. Coastal Plain.

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

Menzel, Jennifer M.; Michael A. Menzel; John C. Kilgo

2005-09-01

Abstract: Bat activity in the southeastern United States is concentrated over riparian areas and wetland habitats. The restoration and creation of wetlands for mitigation purposes is becoming common in the Southeast. Understanding the effects of these restoration efforts on wetland flora and fauna is thus becoming increasingly important. Because bats (Order: Chiroptera) consist of many species that are of conservation concern and are commonly associated with wetland and riparian habitats in the Southeast (making them a good general indicator for the condition of wetland habitats), we monitored bat activity over restored and reference Carolina bays surrounded by pine savanna (Pinusmore » spp.) or mixed pine-hardwood habitat types at the Savannah River Site in South Carolina. In order to determine how wetland restoration efforts affected the bat community, we monitored bat activity above drained Carolina bays pre- and post-restoration. Our results indicate that bat activity was greater over reference (i.e., undrained) than drained bays prior to the restorative efforts. One year following combined hydrologic and vegetation treatment, however, bat activity was generally greater over restored than reference bays. Bat activity was also greater over both reference and restored bays than in random, forested interior locations. We found significantly more bat activity after restoration than prior to restoration for all but one species in the treatment bays, suggesting that Carolina bay restoration can have almost immediate positive impacts on bat activity.« less

Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

NASA Technical Reports Server (NTRS)

Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.;

First Step Towards a Coastal Modelling System for South Africa: a St. Helena Bay Case Study

NASA Astrophysics Data System (ADS)

Collins, C.; Lamont, T.; Loveday, B. R.; Hermes, J. C.; Veitch, J.; Backeberg, B.

2016-02-01

St. Helena Bay, forming part of the southern Benguela ecosystem, is the largest bay on the west coast of South Africa and is a biologically important region for pelagic fish, hake, and rock lobster. To date, only a few infrequent studies have focussed on variations in the bay scale circulation. A monthly ship-based monitoring line, the St. Helena Bay Monitoring Line (SHBML), was initiated in 2000 to determine the seasonal changes in cross-shelf hydrography and biology. Even though there has been an increase in ocean modelling in and around South Africa in recent years, coastal modelling is still in its infancy. The 12-year observational data set in the St. Helena Bay region, the only long-term, cross-shelf, full water column data-set for South Africa, makes this area the perfect natural laboratory for the development of a coastal modelling system. In this study, the climatological mean temperature and salinity from three different ROMS simulations and a HYCOM simulation are evaluated against the in situ observations from the SHBML with the aim of determining the influence of different forcing products, horizontal and vertical resolution as well as vertical coordinate schemes on the vertical structure of the ocean. The model simulations tend to overestimate the temperature and salinity across the shelf, and particularly within St. Helena Bay. Furthermore, the models misrepresent the vertical salinity and temperature structures. Interestingly, below 800m, there is a better agreement between temperature in the models and the in-situ observations. This is the first detailed comparison of modelled and in-situ data for the greater St. Helena Bay area at this scale and the next phase will examine whether the model that is most congruent with the observations resolves the same interannual signals as observed in the in-situ data.

Projectile compositions and modal frequencies on the chemistry of micrometeoroids LDEF experiment

NASA Technical Reports Server (NTRS)

Bernhard, Ronald P.; See, Thomas H.; Hoerz, Friedrich

1993-01-01

The Chemistry of Micrometeoroids Experiment (LDEF instrument A0187-1) exposed witness plates of high-purity gold (greater than 99.99 percent Au) and commercial aluminum (greater than 99 percent Al) with the objective of analyzing the residues of cosmic-dust and orbital-debris particles associated with hypervelocity impact craters. The gold substrates were located approximately 8 deg off LDEF's trailing edge (Bay A03), while the aluminum surfaces resided in Bay A11, approximately 52 deg from LDEF's leading edge. SEM-EDX techniques were employed to analyze the residues associated with 199 impacts on the gold and 415 impacts on the aluminum surfaces. The residues that could be analyzed represent natural or man-made materials. The natural particles dominate at all particle sizes less than 5 micron. It is possible to subdivide both particle populations into subclasses. Chondritic compositions dominate the natural impactors (71 percent), followed by monomineralic, mafic-silicate compositions (26 percent), and by Fe-Ni rich sulfides (approximately 3 percent). Approximately 30 percent of all craters on the gold collectors were caused by man-made debris such as aluminum, paint flakes, and other disintegrated, structural and electronic components. Equations-of-state and associated calculations of shock stresses for typical LDEF impacts into the gold and aluminum substrates suggest that substantial vaporization may have occurred during many of the impacts and is the reason why approximately 50 percent of all craters did not contain sufficient residue to permit analysis by the SEM-EDX technique. After converting the crater diameters into projectile sizes using encounter speeds typical for the trailing-edge and forward-facing (Row 11) directions, and accounting for normalized exposure conditions of the CME collectors, we derived the absolute and relative fluxes of specific projectile classes. The natural impactors encounter all LDEF pointing directions with comparable, modal frequencies suggesting compositional (and dynamic) homogeneity of the interplanetary-dust environment in near-Earth orbit.

Fabrication of Lower Section and Upper Forward Bulkhead Panels of the Multi-Bay Box and Panel Preparation

NASA Technical Reports Server (NTRS)

Velicki, Alexander; Linton, Kim; Hoffman, Krishna; Thrash, Patrick; Pickell, Robert; Turley, Robert

2015-01-01

NASA and the Boeing Co. have been working together under the Environmentally Responsible Aviation Project to develop stitched unitized structure for reduced weight, reduced fuel burn and reduced pollutants in the next generation of commercial aircraft. The structural concept being evaluated is PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure). In the PRSEUS concept, dry carbon fabric, pultruded carbon rods, and foam are stitched together into large preforms. Then these preforms are infused with an epoxy resin into large panels in an out-of-autoclave process. These panels have stiffeners in the length-wise and width-wise directions but contain no fasteners because all stiffeners are stitched to the panel skin. This document contains a description of the fabrication of panels for use in the 30-foot-long Multi-Bay Box test article to be evaluated at NASA LaRC. The document also describes a panel which explores new PRSEUS concepts for applications beyond the Multi-Bay Box.

Evaluation of potential relationships between benthic community structure and toxic metals in Laizhou Bay.

PubMed

Wu, Bin; Song, Jinming; Li, Xuegang

2014-10-15

The objective of the present study was to examine the relationships between benthic community structure and toxic metals using bivariate/multivariate techniques at 17 sediment locations in Laizhou Bay, North China. Sediment chemical data were evaluated against geochemical background values and sediment quality guidelines, which identified Cu and As as contaminants of concern with a moderate potential for adverse effects. Benthic community data were subjected to non-metric multidimensional scaling, which generated four groups of stations. Spearman rank correlation was then employed to explore the relationships between the major axes of heavy metals and benthic community structure. However, weak and insignificant correlations were found between these axes, indicating that contaminants of concern may not be the primary explanatory factors. Polychaeta were abundant in southern Laizhou Bay, serving as a warning regarding the health status of the ecosystem. Integrated sediment quality assessment showed sediments from northern central locations were impaired, displaying less diverse benthos and higher metal contamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ecomorphodynamic Response of Foreshore Saltmarsh to the Implementation of Flood and Erosion Mitigation and Adaptation Structures in a Hypertidal Estuary: Minas Basin, Bay of Fundy, Canada.

NASA Astrophysics Data System (ADS)

Matheson, G.; van Proosdij, D.; Ross, C.

2017-12-01

Flood and erosion mitigations and adaptation structures are often implemented in anthropogenically modified coastal regions, such as dykelands, to protect against coastal hazards. If saltmarshes are to be incorporated into a coastal management plan as a source of coastal defence, it is paramount to understand how ecomorphodynamic feedbacks triggered by implementing these structures can impact saltmarshes. This study examines how these structures, in combination with natural drivers, have precipitated changes in foreshore saltmarsh erosion and progradation rates over varying spatial scales in the hypertidal Minas Basin, located in the upper Bay of Fundy, during the past 80 years. Foreshore change rates (in 25m segments) are obtained using empirical field measurements, geomatics techniques in a geographical information system (GIS), as well as imagery and digital surface models (DSMs) derived from an unmanned aerial vehicle (UAV). Furthermore, UAV DSMs were used to determine infill rates and short-term sediment budgets in saltmarsh borrow pits. Natural cyclical foreshore change rates are observed in the Minas Basin, but are often augmented by the presence of anthropogenic structures. Erosion and progradation rates in individual transects have been observed to be as much as -14.9m/yr and 20.1m/yr, respectively. In individual saltmarsh communities, average change rates have been observed to be as much -3.4m/yr and 2.1m/yr across the entire foreshore. Furthermore, results suggest that under specific environmental conditions some structures (e.g. kickers) work in tandem with saltmarshes to protect the upland by precipitating ecomorphodynamic feedbacks that promote saltmarsh progradation. Conversely, other structures (e.g. foreshore rocking) can exacerbate natural cycles of erosion, locally. Borrow pit studies reveal that although local suspended sediment concentrations, which can vary from 50mg/l to 50000mg/l, play an integral role in pit sedimentation, channel geometry design may play an equally important role in governing infill rates.

Deep bore hole instrumentation along San Francisco Bay Bridges

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

Bakun, W.; Bowman, J.; Clymer, R.

1998-10-01

The Bay Bridges down hole network consists of sensors in bore holes that are drilled 100 ft. into bedrock around and in the San Francisco Bay. Between 2 and 8 instruments have been spaced along the Dumbarton, San Mateo, Bay, and San Rafael bridges. The instruments will provide multiple use data that is important to geotechnical, structural engineering, and seismological studies. The holes are between 100 and 1000 ft deep and were drilled by Caltrans. There are twenty- one sensor packages at fifteen sites. Extensive financial support is being contributed by Caltrans, UCB, LBL, LLNL-LDRD, U.C. Campus/Laboratory Collaboration (CLC) program,more » and USGS. The down hole instrument package contains a three component HS-1 seismometer and three orthogonal Wilcox 73 1 accelerometers, and is capable of recording a micro g from local M = 1.0 earthquakes to 0.5 g strong ground motion form large Bay Area earthquakes.« less

Investigations on classification categories for wetlands of Chesapeake Bay using remotely sensed data

NASA Technical Reports Server (NTRS)

Williamson, F. S. L.

1974-01-01

The use of remote sensors to determine the characteristics of the wetlands of the Chesapeake Bay and surrounding areas is discussed. The objectives of the program are stated as follows: (1) to use data and remote sensing techniques developed from studies of Rhode River, West River, and South River salt marshes to develop a wetland classification scheme useful in other regions of the Chesapeake Bay and to evaluate the classification system with respect to vegetation types, marsh physiography, man-induced perturbation, and salinity; and (2) to develop a program using remote sensing techniques, for the extension of the classification to Chesapeake Bay salt marshes and to coordinate this program with the goals of the Chesapeake Research Consortium and the states of Maryland and Virginia. Maps of the Chesapeake Bay areas are developed from aerial photographs to display the wetland structure and vegetation.

Evidence for natural molecular hydrogen seepage associated with Carolina bays (surficial, ovoid depressions on the Atlantic Coastal Plain, Province of the USA)

NASA Astrophysics Data System (ADS)

Zgonnik, Viacheslav; Beaumont, Valérie; Deville, Eric; Larin, Nikolay; Pillot, Daniel; Farrell, Kathleen M.

2015-12-01

A study of soil gases was made in North Carolina (USA) in and around morphological depressions called "Carolina bays." This type of depression is observed over the Atlantic coastal plains of the USA, but their origin remains debated. Significant concentrations of molecular hydrogen (H2) were detected, notably around the bays. These measurements suggest that Carolina bays are the surficial expression of fluid flow pathways for hydrogen gas moving from depth to the surface. The potential mechanisms of H2 production and transport and the geological controls on the fluid migration pathways are discussed, with reference to the hypothesis that Carolina bays are the result of local collapses caused by the alteration of rock along the deep pathways of H2 migrating towards the surface. The present H2 seepages are comparable to those in similar structures previously observed in the East European craton.

EVALUATING THE INTEGRITY OF SALT MARSHES IN NARRAGANSETT BAY SUB-ESTUARIES USING A WATERSHED APPROACH

EPA Science Inventory

A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay is being used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh t...

Geophysical framework of the northern San Francisco Bay region, California

USGS Publications Warehouse

Langenheim, Victoria; Graymer, Russell W.; Jachens, Robert C.; McLaughlin, Robert J.; Wagner, D.L.; Sweetkind, Donald

2010-01-01

We use geophysical data to examine the structural framework of the northern San Francisco Bay region, an area that hosts the northward continuation of the East Bay fault system. Although this fault system has accommodated ∼175 km of right-lateral offset since 12 Ma, how this offset is partitioned north of the bay is controversial and important for understanding where and how strain is accommodated along this stretch of the broader San Andreas transform margin. Using gravity and magnetic data, we map these faults, many of which influenced basin formation and volcanism. Continuity of magnetic anomalies in certain areas, such as Napa and Sonoma Valleys, the region north of Napa Valley, and the region south of the Santa Rosa Plain, preclude significant (>10 km) offset. Much of the slip is partitioned around Sonoma and Napa Valleys and onto the Carneros, Rodgers Creek, and Green Valley faults. The absence of correlative magnetic anomalies across the Hayward–Rodgers Creek–Maacama fault system suggests that this system reactivated older basement structures, which appear to influence seismicity patterns in the region.

Tidal creek changes at the Sonoma Baylands restoration site

USGS Publications Warehouse

Dingler, John R.; Cacchione, David A.; ,

1998-01-01

Over the past 150 years, human activity has had a major impact on tidal wetlands adjoining the San Francisco Bay-Delta estuary Growing concern about the effect of this change on the ecology of the estuary has prompted Bay area managers to attempt to reclaim tidal wetlands. The Sonoma Baylands Restoration Project is designed to use dredge material to convert 348 acres from farmland to wetland. This paper describes changes to a tidal creek that flows from that restoration site to San Pablo Bay (north San Francisco Bay) through an existing tidal wetland during different phases of the project. Hydrologic measurements near the bottom of the creek and cross-creek profiles show how the creek responded to non-tidal flow conditions introduced by filling the site with dredge materials. At the time of this study, the creek had deepened by approximately 40 cm but had not widened.

Potential Impacts and Management Implications of Climate Change on Tampa Bay Estuary Critical Coastal Habitats

NASA Astrophysics Data System (ADS)

Sherwood, Edward T.; Greening, Holly S.

2014-02-01

The Tampa Bay estuary is a unique and valued ecosystem that currently thrives between subtropical and temperate climates along Florida's west-central coast. The watershed is considered urbanized (42 % lands developed); however, a suite of critical coastal habitats still persists. Current management efforts are focused toward restoring the historic balance of these habitat types to a benchmark 1950s period. We have modeled the anticipated changes to a suite of habitats within the Tampa Bay estuary using the sea level affecting marshes model under various sea level rise (SLR) scenarios. Modeled changes to the distribution and coverage of mangrove habitats within the estuary are expected to dominate the overall proportions of future critical coastal habitats. Modeled losses in salt marsh, salt barren, and coastal freshwater wetlands by 2100 will significantly affect the progress achieved in "Restoring the Balance" of these habitat types over recent periods. Future land management and acquisition priorities within the Tampa Bay estuary should consider the impending effects of both continued urbanization within the watershed and climate change. This requires the recognition that: (1) the Tampa Bay estuary is trending towards a mangrove-dominated system; (2) the current management paradigm of "Restoring the Balance" may no longer provide realistic, attainable goals; (3) restoration that creates habitat mosaics will prove more resilient in the future; and (4) establishing subtidal and upslope "refugia" may be a future strategy in this urbanized estuary to allow sensitive habitat types (e.g., seagrass and salt barren) to persist under anticipated climate change and SLR impacts.

Potential impacts and management implications of climate change on Tampa Bay estuary critical coastal habitats.

PubMed

Sherwood, Edward T; Greening, Holly S

2014-02-01

The Tampa Bay estuary is a unique and valued ecosystem that currently thrives between subtropical and temperate climates along Florida's west-central coast. The watershed is considered urbanized (42 % lands developed); however, a suite of critical coastal habitats still persists. Current management efforts are focused toward restoring the historic balance of these habitat types to a benchmark 1950s period. We have modeled the anticipated changes to a suite of habitats within the Tampa Bay estuary using the sea level affecting marshes model under various sea level rise (SLR) scenarios. Modeled changes to the distribution and coverage of mangrove habitats within the estuary are expected to dominate the overall proportions of future critical coastal habitats. Modeled losses in salt marsh, salt barren, and coastal freshwater wetlands by 2100 will significantly affect the progress achieved in "Restoring the Balance" of these habitat types over recent periods. Future land management and acquisition priorities within the Tampa Bay estuary should consider the impending effects of both continued urbanization within the watershed and climate change. This requires the recognition that: (1) the Tampa Bay estuary is trending towards a mangrove-dominated system; (2) the current management paradigm of "Restoring the Balance" may no longer provide realistic, attainable goals; (3) restoration that creates habitat mosaics will prove more resilient in the future; and (4) establishing subtidal and upslope "refugia" may be a future strategy in this urbanized estuary to allow sensitive habitat types (e.g., seagrass and salt barren) to persist under anticipated climate change and SLR impacts.

77 FR 59180 - Withdrawal of Intent To Prepare a Draft Environmental Impact Statement/Environmental Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-26

... of Ballona Creek including coastal wetlands. Santa Monica Bay Restoration Commission (SMBRC) is the... Restoration Feasibility Study, Los Angeles County, CA AGENCY: Department of the Army, U.S. Army Corps of.../Environmental Impact Report (EIS/EIR) for the Ballona Creek Ecosystem Restoration Feasibility Study in the...

Food web pathway determines how selenium affects aquatic ecosystems: A San francisco Bay case study

USGS Publications Warehouse

Stewart, A.R.; Luoma, S.N.; Schlekat, C.E.; Doblin, M.A.; Hieb, K.A.

2004-01-01

Chemical contaminants disrupt ecosystems, but specific effects may be under-appreciated when poorly known processes such as uptake mechanisms, uptake via diet, food preferences, and food web dynamics are influential. Here we show that a combination of food web structure and the physiology of trace element accumulation explain why some species in San Francisco Bay are threatened by a relatively low level of selenium contamination and some are not. Bivalves and crustacean Zooplankton form the base of two dominant food webs in estuaries. The dominant bivalve Potamocorbula amurensis has a 10-fold slower rate constant of loss for selenium than do common crustaceans such as copepods and the mysid Neomysis mercedis (rate constant of loss, ke = 0.025, 0.155, and 0.25 d-1, respectively). The result is much higher selenium concentrations in the bivalve than in the crustaceans. Stable isotope analyses show that this difference is propagated up the respective food webs in San Francisco Bay. Several predators of bivalves have tissue concentrations of selenium that exceed thresholds thought to be associated with teratogenesis or reproductive failure (liver Se > 15 ??g g-1 dry weight). Deformities typical of selenium-induced teratogenesis were observed in one of these species. Concentrations of selenium in tissues of predators of Zooplankton are less than the thresholds. Basic physiological and ecological processes can drive wide differences in exposure and effects among species, but such processes are rarely considered in traditional evaluations of contaminant impacts.

Examining Reservoir Influences on Fluvial Sediment Supply to Estuaries and Coastal Oceans with Sediment Geochronologies: Example from Conowingo Reservoir (Upper Chesapeake Bay, USA)

NASA Astrophysics Data System (ADS)

Palinkas, C. M.; Russ, E.

2016-12-01

The flux of fluvial sediment to estuaries and coastal oceans is often interrupted by natural and anthropogenic influences. Here, we focus on river dams, which alter the connection between rivers and their receiving basins via sediment sequestration in their reservoirs. Sediments are effectively trapped until river discharge is high enough to create flow velocities capable of resuspending sediment. Sediment resuspension often varies within the reservoir, driven by morphological features such as channels and islands. Thus, sediment residence times in the reservoir are often highly variable in space and time. This study focuses on reading the sedimentary record in one such system - the reservoir upstream of Conowingo Dam, built in the late 1920s and the last and largest dam on the Susquehanna River (Maryland, USA) before it enters Chesapeake Bay. This study establishes geochronologies of reservoir sedimentation on seasonal to decadal time scales with a variety of techniques (e.g., natural and anthropogenic radioisotopes (7Be, 210Pb, 137Cs), coal from mining in the watershed) to interpret observed down-core sedimentary structures and characteristics (grain size, organic content). These observations reveal spatial and temporal patterns of sediment deposition and/or erosion. Placed within the broader context of reservoir geomorphology, these results can improve predictions of sediment supply to downstream environments, in this case Chesapeake Bay, where it can impact water quality and/or benthic organisms.

Genetic structure of lake whitefish, Coregonus clupeaformis, populations in the northern main basin of Lake Huron

USGS Publications Warehouse

Stott, Wendylee; Ebener, Mark P.; Mohr, Lloyd; Schaeffer, Jeff; Roseman, Edward F.; Harford, William J.; Johnson, James E.; Fietsch, Cherie-Lee

2012-01-01

Genetic analysis of spawning lake whitefish (Coregonus clupeaformis) from six sites in the main basin of Lake Huron was conducted to determine population structure. Samples from fisheryindependent assessment surveys in the northwest main basin were analyzed to determine the relative contributions of lake whitefish genetic populations. Genetic population structure was identified using data from seven microsatellite DNA loci. One population was identified at Manitoulin Island, one to two were observed in the east-central main basin (Fishing Island and Douglas Point), and one to two populations were found in the northwest (Thunder Bay and Duncan Bay). The genetic identity of collections from Duncan Bay and Thunder Bay was not consistent among methods used to analyze population structure. Low genetic distances suggested that they comprised one population, but genic differences indicated that they may constitute separate populations. Simulated data indicated that the genetic origins of samples from a mixed-fishery could be accurately identified, but accuracy could be improved by incorporating additional microsatellite loci. Mixture analysis and individual assignment tests performed on mixed-stock samples collected from the western main basin suggested that genetic populations from the east-central main basin contributed less than those from the western main basin and that the proportional contribution of each baseline population was similar in each assessment sample. Analysis of additional microsatellite DNA loci may be useful to help improve the precision of the estimates, thus increasing our ability to manage and protect this valuable resource.

Discovery of a Giant, 200,000 Light-year Long Wave Rolling Through the Perseus Galaxy Cluster

NASA Astrophysics Data System (ADS)

Walker, Stephen; Hlavacek-Larrondo, Julie; Gendon-Marsolais, Marie-Lou; Fabian, Andy; Intema, Huib; Sanders, Jeremy

2018-01-01

Deep observations of nearby galaxy clusters with Chandra have revealed concave 'bay' structures in a number of clusters (Perseus, Centaurus and Abell 1795), which have similar X-ray and radio properties. These bays have all the properties of cold fronts brought about by minor mergers causing the cluster gas to slosh around in the gravitational potential. At these cold fronts the temperature rises and density falls sharply. Unusually, in the case of the 'bays' these cold fronts are concave rather than convex. By comparing to simulations of gas sloshing, we find that the bay in the Perseus cluster bears a striking resemblance in its size, location and thermal structure, to a giant (≈50 kpc) wave resulting from Kelvin-Helmholtz instabilities. Such instabilities are commonly seen on far smaller scales in nature, from billow clouds in the Earth's atmosphere, to structures in the cloud belts of gas giant planets. Here we are witnessing this phenomenon on the largest scale ever seen, twice the size of the Milky Way galaxy. The morphology of this structure seen in Perseus can be compared to simulations to put constraints on the initial magnetic pressure throughout the overall cluster before the sloshing occurs. Such Kelvin-Helmholtz features in galaxy clusters have long been predicted by simulations, but it is only now that they have finally been observed, opening up an important new way to probe the physics of the intracluster medium, which contains the majority of the baryonic matter in clusters.

Barrier island breach evolution: Alongshore transport and bay-ocean pressure gradient interactions

USGS Publications Warehouse

Safak, Ilgar; Warner, John C.; List, Jeffrey

2016-01-01

Physical processes controlling repeated openings and closures of a barrier island breach between a bay and the open ocean are studied using aerial photographs and atmospheric and hydrodynamic observations. The breach site is located on Pea Island along the Outer Banks, separating Pamlico Sound from the Atlantic Ocean. Wind direction was a major control on the pressure gradients between the bay and the ocean to drive flows that initiate or maintain the breach opening. Alongshore sediment flux was found to be a major contributor to breach closure. During the analysis period from 2011 to 2016, three hurricanes had major impacts on the breach. First, Hurricane Irene opened the breach with wind-driven flow from bay to ocean in August 2011. Hurricane Sandy in October 2012 quadrupled the channel width from pressure gradient flows due to water levels that were first higher on the ocean side and then higher on the bay side. The breach closed sometime in Spring 2013, most likely due to an event associated with strong alongshore sediment flux but minimal ocean-bay pressure gradients. Then, in July 2014, Hurricane Arthur briefly opened the breach again from the bay side, in a similar fashion to Irene. In summary, opening and closure of breaches are shown to follow a dynamic and episodic balance between along-channel pressure gradient driven flows and alongshore sediment fluxes.

Radionuclides as tracer for submarine groundwater discharge (SGD) research at Dapeng Bay in Southern Taiwan

NASA Astrophysics Data System (ADS)

Huang, Jun-Chen; Su, Chih-Chieh

2017-04-01

Conventionally, river is the most important source for delivering nutrients, such as nitrogen, phosphorus and silicon, and trace elements into the ocean. The issues of land-sea interaction by rivers have been long-tern concerned and studied, on contrary, the pathway and impact through submarine groundwater discharge (SGD) is still unclear and the relevant researches need to be strengthened. The research site, Dapeng Bay, is located at Pingtung County in Southern Taiwan. Dapeng Bay is an bag-shape lagoon with a sand spit serving as the single outlet of the bay. The longshore currents transport sediments which delivered by Donggang and Linbian Rivers deposited at the nearshore and eventually form the semi-enclosed shallow bay. In the Dapeng Bay, there is no river poured into the lagoon and the main sources of freshwater are rainwater, domestic wastewater and fish ponds etc. The tidal driven water exchange between lagoon and ocean is through the sand spit outlet. The purpose of this study is to evaluate the weighting and seasonal change between SGD and riverine input in the Dapeng Bay. The radium isotopes, 223Ra (11.4d), 224Ra (3.7d), 226Ra (1600y), 228Ra (5.7y), were used as tracers for assessing SGD and riverine inputs. Samples were collected by using MnO2-coated fibers for radium isotopes adsorption.

Spatial Modeling of Tsunami Impact in Manado City using Geographic Information System

NASA Astrophysics Data System (ADS)

Kumaat, J. C.; Kandoli, S. T. B.; Laeloma, F.

2018-02-01

Manado City is a coastal area in the shape of a bay. Manado Bay is a water body that protrudes in the area of Manado City where the condition of this region is likely to have a tsunami threat. Manado Bay is home to several rivers such as Tondano River has a geological history of both land and sea. There are several active faults, such as in the sea, subduction of subplate in the north of the island, Mayu mountain plate, and Sangihe plate east of North Sulawesi. The purpose of this study is divided into two parts: General purpose is to describe GIS-based disaster mitigation that can be done to minimize disaster risk if Tsunami disaster occurs in coastal area of Manado Bay, while special purpose consists of 3 parts, namely: 1. mapping of zone- Tsunami vulnerability zone of Manado Bay; 2. mapping the distance and time of the scenario of the Manado Bay Tsunami evacuation route; 3. mapping of the number of buildings and roads exposed to the Manado Bay Tsunami. Data collection techniques use secondary data collection techniques. Secondary data comes from related institutions or institutions, libraries, or individual archives. The data collection is also continued by direct observation. Direct observation is meant by direct observation by using a checklist for secondary data adjustment and then the determination of coordinate point with Global Position System (GPS) at some tsunami location.

Modeling of Waves, Hydrodynamics and Sediment Transport for Protection of Wetlands at Braddock Bay, New York

DTIC Science & Technology

2015-03-01

entrance were evaluated on their ability to reduce potential impacts of waves and currents on wet- lands. Study results indicated all three proposed...transport de- veloped were used in the evaluation of proposed solutions. The prelimi- nary modeling results helped to assess general sediment pattern...Corps of Engineers (USACE), Buffalo Dis- trict, is conducting a study to evaluate shoreline protection measures for coastal wetlands at Braddock Bay

A Summary of 20 Years of Forest Monitoring in Cinnamon Bay Watershed, St. John, U.S. Virgin Islands.

Treesearch

Peter L. Weaver

2006-01-01

St. John, and probably the Cinnamon Bay watershed, has a history of human use dating to 1700 B.C. The most notable impacts, however, occurred from 1730 to 1780 when sugar cane and cotton production peaked on the island. As agriculture was abandoned, the island regenerated in secondary forest, and in 1956, the Virgin Islands National Park was created. From 1983 to 2003...

Community structure and coral status across reef fishing intensity gradients in Palk Bay reef, southeast coast of India.

PubMed

Manikandan, B; Ravindran, J; Shrinivaasu, S; Marimuthu, N; Paramasivam, K

2014-10-01

Coral reef fishes are exploited without the knowledge of their sustainability and their possible effect in altering the community structure of a coral reef ecosystem. Alteration of the community structure could cause a decline in the health of coral reefs and its services. We documented the coral community structure, status of live corals and reef fish assemblages in Palk Bay at the reef fishing hotspots and its nearby reef area with minimum fishing pressure and compared it with a control reef area where reef fishing was banned for more than two decades. The comparison was based on the percent cover of different forms of live corals, their diversity and the density and diversity of reef fishes. The reef fish stock in the reef fishing hotspots and its neighbouring reef was lower by 61 and 38%, respectively compared to the control reef. The herbivore fish Scarus ghobban and Siganus javus were exploited at a rate of 250 and 105 kg month(-1) fishermen(-1), respectively, relatively high comparing the small reef area. Live and dead corals colonized by turf algae were predominant in both the reef fishing hotspots and its nearby coral ecosystems. The percent cover of healthy live corals and live corals colonized by turf algae was <10 and >80%, respectively, in the intensively fished coral ecosystems. The corals were less diverse and the massive Porites and Favia colonies were abundant in the intensive reef fishing sites. Results of this study suggest that the impact of reef fish exploitation was not solely restricted to the intensively fished reefs, but also to the nearby reefs which play a critical role in the resilience of degraded reef ecosystems.

High-resolution marine seismic reflection data from the San Francisco Bay area

USGS Publications Warehouse

Childs, Jonathan R.; Hart, Patrick; Bruns, Terry R.; Marlow, Michael S.; Sliter, Ray

2000-01-01

Between 1993 and 1997, the U.S. Geological Survey acquired high-resolution, marine seismic-reflection profile data across submerged portions of known and inferred upper crustal fault zones throughout the greater San Francisco Bay area. Surveys were conducted oversouth San Francisco Bay in the vicinity of the San Bruno shoal (roughly between the San Francisco and Oakland airports), over the offshore extension of the San Andreas fault system west of the Golden Gate, over the Hayward fault to Rodgers Creek fault step-over in San Pablo Bay, and over the Kirby Hills fault where it crosses the western Sacramento Delta. Reconnaissance profiles were acquired elsewhere throughout the San Francisco and San Pablo Bays. These data were acquired by the U.S. Geological Survey, Western Coastal and Marine Geology Team, under the auspices of the Central California/San Francisco Bay Earthquake Hazards Project. Analysis and interpretation of some of these profiles has been published by Marlow and others (1996, 1999). Further analysis and interpretation of these data are available in a USGS. Professional Paper Crustal Structure of the Coastal and Marine San Francisco Bay Region, T. Parsons, editor, http://geopubs.wr.usgs.gov/prof-paper/pp1658/ [link added 2012 mfd].

Comparing two Bayes methods based on the free energy functions in Bernoulli mixtures.

PubMed

Yamazaki, Keisuke; Kaji, Daisuke

2013-08-01

Hierarchical learning models are ubiquitously employed in information science and data engineering. The structure makes the posterior distribution complicated in the Bayes method. Then, the prediction including construction of the posterior is not tractable though advantages of the method are empirically well known. The variational Bayes method is widely used as an approximation method for application; it has the tractable posterior on the basis of the variational free energy function. The asymptotic behavior has been studied in many hierarchical models and a phase transition is observed. The exact form of the asymptotic variational Bayes energy is derived in Bernoulli mixture models and the phase diagram shows that there are three types of parameter learning. However, the approximation accuracy or interpretation of the transition point has not been clarified yet. The present paper precisely analyzes the Bayes free energy function of the Bernoulli mixtures. Comparing free energy functions in these two Bayes methods, we can determine the approximation accuracy and elucidate behavior of the parameter learning. Our results claim that the Bayes free energy has the same learning types while the transition points are different. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of strong monsoon winds on the water quality around a marine cage-culture zone in a shallow and semi-enclosed bay in Taiwan.

PubMed

Huang, Yuan-Chao Angelo; Huang, Shou-Chung; Meng, Pei-Jie; Hsieh, Hernyi Justin; Chen, Chaolun Allen

2012-04-01

Influences of marine cage culture and monsoonal disturbances, northeasterly (NE) and southwesterly (SW) monsoons on the proximal marine environment were investigated across a gradient of sites in a semi-enclosed bay, Magong Bay (Penghu Islands, Taiwan). Elevated levels of ammonia produced by the cages were the main pollutant and distinguished the cage-culture and intermediary zones (1000 m away from the cages) from the reference zone in the NE monsoon, indicating currents produced by the strong monsoon may have extended the spread of nutrient-enriched waters without necessarily flushing such effluents outside Magong Bay. Moreover, the levels of chlorophyll-a, dissolved oxygen, and turbidity were distinguishable between two seasons, suggesting that resuspension caused by the NE monsoon winds may also influence the water quality across this bay. It indicated that the impacts of marine cage culture vary as a function of distance, and also in response to seasonal movements of water driven by local climatic occurrences. Copyright © 2012 Elsevier Ltd. All rights reserved.

Oyster reef restoration in controlling coastal pollution around India: A viewpoint.

PubMed

Chakraborty, Parthasarathi

2017-02-15

Coastal waters receive large amounts of nutrients and pollutants from different point and nonpoint sources through bays and estuaries. Excess supply of nutrients in coastal waters may have detrimental effects, leading to hypoxia and anoxia from eutrophication. Reduction in concentrations of excess nutrients/pollutants in bays/estuarine system is must for healthy coastal ecosystem functioning. Conservations of bays, estuaries and coastal zones are must for sustainable development in any maritime country. Excellent ability of oyster in removing and controlling the concentrations of nutrients, pollutants, suspended particulate matters from bays and estuarine waters stimulated me to provide a viewpoint on oyster reef restoration in controlling nutrient/heavy metals fluxes and marine coastal pollution around India. Oyster reefs restoration may decrease nutrient and heavy metals fluxes in coastal waters and reduce the intensity of oxygen depletion in the coastal Arabian Sea (seasonal) and Bay of Bengal. However, extensive research is recommended to understand the impact of oyster reef restoration in controlling coastal pollution which is essential for sustainable development around India. Copyright © 2016 Elsevier Ltd. All rights reserved.

Numerical modeling of salt marsh morphological change induced by Hurricane Sandy

USGS Publications Warehouse

Hu, Kelin; Chen, Qin; Wang, Hongqing; Hartig, Ellen K.; Orton, Philip M.

2018-01-01

The salt marshes of Jamaica Bay serve as a recreational outlet for New York City residents, mitigate wave impacts during coastal storms, and provide habitat for critical wildlife species. Hurricanes have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. In this study, the Delft3D modeling suite was utilized to examine the effects of Hurricane Sandy (2012) on salt marsh morphology in Jamaica Bay. Observed marsh elevation change and accretion from rod Surface Elevation Tables and feldspar Marker Horizons (SET-MH) and hydrodynamic measurements during Hurricane Sandy were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model. The model results agreed well with in situ field measurements. The validated model was then used to detect salt marsh morphological change due to Sandy across Jamaica Bay. Model results indicate that the island-wide morphological changes in the bay's salt marshes due to Sandy were in the range of −30 mm (erosion) to +15 mm (deposition), and spatially complex and heterogeneous. The storm generated paired deposition and erosion patches at local scales. Salt marshes inside the west section of the bay showed erosion overall while marshes inside the east section showed deposition from Sandy. The net sediment amount that Sandy brought into the bay is only about 1% of the total amount of reworked sediment within the bay during the storm. Numerical experiments show that waves and vegetation played a critical role in sediment transport and associated wetland morphological change in Jamaica Bay. Furthermore, without the protection of vegetation, the marsh islands of Jamaica Bay would experience both more erosion and less accretion in coastal storms.

Metagenomic evidence for reciprocal particle exchange between the mainstem estuary and lateral bay sediments of the lower Columbia River

PubMed Central

Smith, Maria W.; Davis, Richard E.; Youngblut, Nicholas D.; Kärnä, Tuomas; Herfort, Lydie; Whitaker, Rachel J.; Metcalf, William W.; Tebo, Bradley M.; Baptista, António M.; Simon, Holly M.

2015-01-01

Lateral bays of the lower Columbia River estuary are areas of enhanced water retention that influence net ecosystem metabolism through activities of their diverse microbial communities. Metagenomic characterization of sediment microbiota from three disparate sites in two brackish lateral bays (Baker and Youngs) produced ∼100 Gbp of DNA sequence data analyzed subsequently for predicted SSU rRNA and peptide-coding genes. The metagenomes were dominated by Bacteria. A large component of Eukaryota was present in Youngs Bay samples, i.e., the inner bay sediment was enriched with the invasive New Zealand mudsnail, Potamopyrgus antipodarum, known for high ammonia production. The metagenome was also highly enriched with an archaeal ammonia oxidizer closely related to Nitrosoarchaeum limnia. Combined analysis of sequences and continuous, high-resolution time series of biogeochemical data from fixed and mobile platforms revealed the importance of large-scale reciprocal particle exchanges between the mainstem estuarine water column and lateral bay sediments. Deposition of marine diatom particles in sediments near Youngs Bay mouth was associated with a dramatic enrichment of Bacteroidetes (58% of total Bacteria) and corresponding genes involved in phytoplankton polysaccharide degradation. The Baker Bay sediment metagenome contained abundant Archaea, including diverse methanogens, as well as functional genes for methylotrophy and taxonomic markers for syntrophic bacteria, suggesting that active methane cycling occurs at this location. Our previous work showed enrichments of similar anaerobic taxa in particulate matter of the mainstem estuarine water column. In total, our results identify the lateral bays as both sources and sinks of biogenic particles significantly impacting microbial community composition and biogeochemical activities in the estuary. PMID:26483785

CCN concentrations and BC warming influenced by maritime ship emitted aerosol plumes over southern Bay of Bengal.

PubMed

Ramana, M V; Devi, Archana

2016-08-02

Significant quantities of carbon soot aerosols are emitted into pristine parts of the atmosphere by marine shipping. Soot impacts the radiative balance of the Earth-atmosphere system by absorbing solar-terrestrial radiation and modifies the microphysical properties of clouds. Here we examined the impact of black carbon (BC) on net warming during monsoon season over southern Bay-of-Bengal, using surface and satellite measurements of aerosol plumes from shipping. Shipping plumes had enhanced the BC concentrations by a factor of four around the shipping lane and exerted a strong positive influence on net warming. Compiling all the data, we show that BC atmospheric heating rates for relatively-clean and polluted-shipping corridor locations to be 0.06 and 0.16 K/day respectively within the surface layer. Emissions from maritime ships had directly heated the lower troposphere by two-and-half times and created a gradient of around 0.1 K/day on either side of the shipping corridor. Furthermore, we show that ship emitted aerosol plumes were responsible for increase in the concentration of cloud condensation nuclei (CCN) by an order of magnitude that of clean air. The effects seen here may have significant impact on the monsoonal activity over Bay-of-Bengal and implications for climate change mitigation strategies.

Coliform contamination of a coastal embayment: Sources and transport pathways

USGS Publications Warehouse

Weiskel, P.K.; Howes, B.L.; Heufelder, G.R.

1996-01-01

Fecal bacterial contamination of nearshore waters has direct economic impacts to coastal communities through the loss of shellfisheries and restrictions of recreational uses. We conducted seasonal measurements of fecal coliform (FC) sources and transport pathways contributing to FC contamination of Buttermilk Bay, a shallow embayment adjacent to Buzzards Bay, MA. Typical of most coastal embayments, there were no direct sewage discharges (i.e., outfalls), and fecal bacteria from human, domestic animal, and wildlife pools entered open waters primarily through direct deposition or after transport through surface waters or groundwaters. Direct fecal coliform inputs to bay waters occurred primarily in winter (December-March) from waterfowl, ~33 x 1012 FC yr-1 or ~67% of the total annual loading. Effects of waterfowl inputs on bay FC densities were mitigated by their seasonality, wide distribution across the bay surface, and the apparent limited dispersal from fecal pellets. On-site disposal of sewage by septic systems was the single largest FC source in the watershed-embayment system, 460 x 1012 FC yr-1, but due to attenuation during subsurface transport only a minute fraction, < 0.006 x 1012 FC yr-1, reached bay waters (<0.01% of annual input to bay). Instead, surface water flows, via storm drains and natural streams under both wet- and dry-weather conditions, contributed the major terrestrial input, 12 x 1012 FC yr-1 (24% of annual input), all from animal sources. Since most of the surface water FC inputs were associated with periodic, short-duration rain events with discharge concentrated in nearshore zones, wet-weather flows were found to have a disproportionately high impact on nearshore FC levels. Elution of FC from shoreline deposits of decaying vegetation (wrack) comprised an additional coliform source. Both laboratory and field experiments suggest significant elution of bacteria from wrack, ~3 x 1012 FC yr-1 on a bay-wide basis (6% of annual input), primarily by periodic tidal flooding and possibly by major rain events. Release of coliforms during resuspension of subtidal sediments was estimated to be a minor source in this system (<1.5 x 1012 FC yr-1 or < 3% of annual input), primarily associated with large storm events in the fall and winter. Based upon the relative source strengths and the spatial and temporal patterns of FC input to Buttermilk Bay, it appears that management practices in similar settings should account for migratory waterfowl, but remediation efforts should focus on the redirection of stormwater runoff through the groundwater transport pathway.

Solution accuracies of finite element reentry heat transfer and thermal stress analyses of Space Shuttle Orbiter

NASA Technical Reports Server (NTRS)

Ko, William L.

1988-01-01

Accuracies of solutions (structural temperatures and thermal stresses) obtained from different thermal and structural FEMs set up for the Space Shuttle Orbiter (SSO) are compared and discussed. For studying the effect of element size on the solution accuracies of heat-transfer and thermal-stress analyses of the SSO, five SPAR thermal models and five NASTRAN structural models were set up for wing midspan bay 3. The structural temperature distribution over the wing skin (lower and upper) surface of one bay was dome shaped and induced more severe thermal stresses in the chordwise direction than in the spanwise direction. The induced thermal stresses were extremely sensitive to slight variation in structural temperature distributions. Both internal convention and internal radiation were found to have equal effects on the SSO.

Heavy-mineral provenance in an estuarine environment, Willapa Bay, Washington, USA: palaeogeographic implications and estuarine evolution

USGS Publications Warehouse

Luepke Bynum, Gretchen

2007-01-01

Modern sediments from representative localities in Willapa Bay, Washington, comprise two principal heavy-mineral suites. One contains approximately equivalent amounts of hornblende, orthopyroxene, and clinopyroxene; this is derived from the Columbia River, which discharges into the Pacific Ocean a short distance south of the bay. The other suite, dominated by clinopyroxene, is restricted to sands of rivers flowing into the bay from the east. The heavy-mineral distributions within the bay suggest that sand discharged from the Columbia River, borne north by longshore transport and carried into the bay by tidal currents, accounts for nearly all of the sand within the interior of Willapa Bay today. Pleistocene deposits on the east side of the bay contain three heavy-mineral assemblages, two of which are identical to the modern assemblages described above. These assemblages reflect the relative influence of tidal and fluvial processes on the Late Pleistocene deposits (100,000–200,000 BP. Amino acid racemization in Quaternary shell deposits at Willapa Bay, Washington. Geochimica et Cosmochimica Acta 43, 1505–1520). They are also consistent with those processes inferred on the basis of sedimentary structures and stratigraphic relations in about two-thirds of the samples examined. Anomalies can be explained by recycling of sand from older deposits. The persistence of the two heavy-mineral suites suggests that the pattern of estuarine sedimentation in Late Pleistocene deposits closely resembled that of the modern bay. The third heavy-mineral suite is enriched in epidote and occurs in a few older Pleistocene units. On the north side of the bay, the association of this suite with southwest-directed foresets in cross-bedded gravel indicates derivation from the northeast, perhaps from an area of glacial outwash. The presence of this suite in ancient estuarine sands exposed on the northeast side of the bay suggests that input from this northerly source may have intermittently dominated Willapa Bay deposition in the past.

The coupling of bay hydrodynamics with sediment supply and micro-tidal wetland stability under high rates of relative sea level rise

NASA Astrophysics Data System (ADS)

Wang, J.; Xu, K.; Restreppo, G. A.; Bentley, S. J.; Meng, X.; Zhang, X.

2017-12-01

Due to global sea level rise, local subsidence and sediment deficit, the Mississippi River (MR) deltaic plain has lost a total of 25% of coastal Louisiana's wetlands during the last century, leading to huge losses of ecological services, economic and social crises. Ecosystem-based restoration strategies which rely on coastal system processes and feedbacks are urgently needed. Understanding linkages between estuarine and coastal systems and the adjacent marshlands will help the designing strategies. To investigate bay hydrodynamics and its impacts on the adjacent micro-tidal wetland stability, hourly measurements of wave, tidal current, and benthic sediment concentration in summer, winter, and spring of 2015-2016 were conducted in Fourleague Bay, Louisiana, USA. The bay-marsh system has been stable for almost 80 years under high relative sea level rising rate, which is 11 km southeast of the Atchafalaya River mouth, with a water depth of 1-3 m. High-temporal resolution data indicate that benthic sediment resuspension is mainly caused by wind-driven waves with a dominant periodicity of 4.8 d. The sediment flux reaches 28 g·m-1·s-1 per unit depth in cm during the events. Net sediment transport is northwestward in summer, and southeastward in winter and spring. Sediment flux available for surrounding marsh varies from 0-500 g·m-1·s-1. An optimal inundation depth of 50 cm is estimated by the equilibrium wetland elevation change model under high relative sea level rising rate of 1.57 cm·yr-1. Seasonal variations of river discharge and wind direction (particularly speeds >3 m·s-1) greatly impact potential sediment contribution from bay to the surrounding wetlands. Three sediment transport regimes are concluded based on the seasonal variations of river discharge and wind direction: the `bypassing' season, the resuspension-accumulation season, and the combined `bypassing' and resuspension-accumulation season. The bay hydrodynamic processes and their impacts on the stability of surrounding wetlands fill in our knowledge gaps on how the micro tidal estuarine-marsh system responds to the fast relative sea level rise, and provide valuable information for future ecological restoration plans in the micro tidal deltas like the MR delta.

Orion Crew Module Structural Test Article Transport from SLF to

NASA Image and Video Library

2016-11-15

A transporter carrying the Orion crew module structural test article (STA) in its container arrives at the low bay entrance of the Neil Armstrong Operations and Checkout Building at NASA's Kennedy Space Center in Florida. The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article will be moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Unbagging

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, the protective covering was removed from the Orion crew module structural test article (STA). It remains secured on the bottom of its transport container. The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Lift & Uncrating

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians with Lockheed Martin assist as a crane lifts the cover away from the container holding the Orion crew module structural test article (STA). The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Transport from SLF to

NASA Image and Video Library

2016-11-15

A transporter carrying the Orion crew module structural test article (STA) in its container arrives inside the low bay of the Neil Armstrong Operations and Checkout Building at NASA's Kennedy Space Center in Florida. The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article will be moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Lift & Uncrating

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, a crane lifts the cover up from the container holding the Orion crew module structural test article (STA). The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.

Orion Crew Module Structural Test Article Unbagging

NASA Image and Video Library

2016-11-15

Inside the Neil Armstrong Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians with Lockheed Martin look over the Orion crew module structural test article (STA) secured on the bottom of its transport container. The STA arrived aboard NASA's Super Guppy aircraft at the Shuttle Landing Facility operated by Space Florida. The test article was moved inside the facility's high bay for further testing. The Orion spacecraft will launch atop NASA’s Space Launch System rocket on EM-1, its first deep space mission, in late 2018.