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Full-Text Articles in Life Sciences

Liver Carcinogenesis In A Non-Migratory Fish: The Association With Polycyclic Aromatic Hydrocarbon Exposure, Wolfgang K. Vogelbein, M. A. Unger Jan 2006

Liver Carcinogenesis In A Non-Migratory Fish: The Association With Polycyclic Aromatic Hydrocarbon Exposure, Wolfgang K. Vogelbein, M. A. Unger

VIMS Articles

Field and laboratory studies indicate a strong positive association between exposure to chemical pollutants in aquatic environments and development of neoplasia in fishes. This brief communication reviews some of the more important North American and European studies that have been conducted on this relationship. We then review work conducted on a small nonmigratory estuarine cyprinodontid teleost fish, the mummichog (Fundulus heteroclitus) in the industrialized Elizabeth River, Virginia USA. Histopathological surveys of mummichogs from variously degraded habitats indicate an association between PAH exposure and development of neoplasia. We have observed non-neoplastic lesions, preneoplasms and hepatic, biliary, exocrine pancreatic and vascular neoplasms …


Temporal And Vertical Dynamics In Picoplankton Photoheterotrophic Production In The Subtropical North Pacific Ocean, M. J. Church, H. W. Ducklow, Et Al Jan 2006

Temporal And Vertical Dynamics In Picoplankton Photoheterotrophic Production In The Subtropical North Pacific Ocean, M. J. Church, H. W. Ducklow, Et Al

VIMS Articles

Heterotrophic microbial production is a fundamental determinant in the flow of bioelements and energy within the pelagic ecosystems of the open ocean. To characterize the temporal dynamics in rates of heterotrophic picoplankton production (HPP), we examined vertical profiles of H-3-leucine (H-3-leu) and [methyl-H-3]-thymidine (H-3-TdR) incorporation at Stn ALOHA (22 degrees 45'N, 158 degrees W) in the oligotrophic North Pacific Ocean. Euphotic zone rates of H-3-leu and H-3-TdR incorporation were measured in situ under light and dark conditions on cruises to Stn ALOHA between April 2000 and August 2005. Rates of H-3-leu and H-3-TdR incorporation were elevated in the well-lit upper …


A Perspective On Two Decades Of Policies And Regulations Influencing The Protection And Restoration Of Submerged Aquatic Vegetation In Chesapeake Bay, Usa, R J. Orth, Ra Batiuk, Pw Bergstrom, Ken Moore Nov 2002

A Perspective On Two Decades Of Policies And Regulations Influencing The Protection And Restoration Of Submerged Aquatic Vegetation In Chesapeake Bay, Usa, R J. Orth, Ra Batiuk, Pw Bergstrom, Ken Moore

VIMS Articles

Seagrasses along with many other species of freshwater rooted submerged macrophytes in Chesapeake Bay (collectively called SAV) underwent serious declines in population abundances in the 1970s and have not as yet rebounded to previous levels. Cooperative efforts by scientists, politicians, federal and state resource managers, and the general public have developed policies and plans to protect, preserve and enhance SAV populations of Chesapeake Bay. These include the Chesapeake Bay Agreements (1983, 1987, 1992, 1993, 2000), an SAV Management Policy and Implementation Plan for Chesapeake Bay and Tidal Tributaries (1989 and 1990), Chesapeake Bay Blue Crab Fishery Management Plan (1997), as …


Characterization Of The Dust/Smoke Aerosol That Settled East Of The World Trade Center (Wtc) In Lower Manhattan After The Collapse Of The Wtc 11 September 2001, Paul J. Lioy, Clifford P. Weisel, Et Al, Robert C. Hale Jul 2002

Characterization Of The Dust/Smoke Aerosol That Settled East Of The World Trade Center (Wtc) In Lower Manhattan After The Collapse Of The Wtc 11 September 2001, Paul J. Lioy, Clifford P. Weisel, Et Al, Robert C. Hale

VIMS Articles

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol plume impacting many workers, residents, and commuters during the first few days after 11 September 2001. Three bulk samples of the total settled dust and smoke were collected at weather-protected locations east of the WTC on 16 and 17 September 200 1; these samples are representative of the generated material that settled immediately after the explosion and fire and the concurrent collapse of the two structures. We analyzed each sample, not differentiated by particle Size, for inorganic and organic composition. In the …


Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk Jan 2002

Photochemical Production Of Dissolved Inorganic Nitrogen And Primary Amines From Dissolved Organic Nitrogen In Waters Of Two Estuaries And Adjacent Surficial Groundwaters, Dj Koopmans, Da Bronk

VIMS Articles

Recent studies have shown that in a number of humic-rich surface waters in North America, NH4+ is released when dissolved organic matter (DOM) is exposed to sunlight. However, photochemical NH4+ production has not been observed in all surface waters, and factors that contribute to it are not well understood. We hypothesized that the presence or absence of NH4+ photoproduction may be affected by the light exposure history of DOM, The present study was undertaken to determine whether DOM from surficial groundwaters, with minimal light exposure history, would produce labile nitrogen (N) photoproducts more consistently, In this study, estuarine surface waters …


Photo Synthesis/Irradiance Relationships In The Ross Sea, Antarctica, And Their Control By Phytoplankton Assemblage Composition And Environmental Factors, C. M. Van Hilst, Walker O. Smith Jr. Jan 2002

Photo Synthesis/Irradiance Relationships In The Ross Sea, Antarctica, And Their Control By Phytoplankton Assemblage Composition And Environmental Factors, C. M. Van Hilst, Walker O. Smith Jr.

VIMS Articles

The photosynthetic parameters of natural phytoplankton assemblages from the Ross Sea, Antarctica, as well as unialgal cultures of the diatom Pseudonitzschia sp. and the colonial haptophyte Phaeocystis antarctica were investigated to determine if differential responses to irradiance could explain the distribution of phytoplankton in the Ross Sea. Field assemblages had photosynthetic responses that suggested acclimation to low irradiance levels, and the initial rate of photosynthesis per unit chlorophyll (a) and the theoretical maximum rate of production (p(max)(B)) averaged 0,083 mg C (mg chl a)(-1) h(-1) (mumol m(-2) s(-1))(-1) and 2,40 mg C (mg chl a)(-1) h(-1), respectively. An increase in …


Changes In Bacterioplankton Metabolic Capabilities Along A Salinity Gradient In The York River Estuary, Virginia, Usa, G. E. Schultz, H. W. Ducklow Sep 2000

Changes In Bacterioplankton Metabolic Capabilities Along A Salinity Gradient In The York River Estuary, Virginia, Usa, G. E. Schultz, H. W. Ducklow

VIMS Articles

Changes in metabolic capabilities of bacterial communities along the estuarine salinity gradient may affect the extent of organic matter processing and bacterial growth and accumulation during transit through the system; As part of a larger study of estuarine microbial processes, we attempted to quantify differences in bacterial community structure using Biolog plates. Biolog GN plates (Biolog, Inc., Hayward, CA, USA) were used to determine differences in bacterioplankton community metabolic potential. Biolog GN microplates are 96-well microtiter plates in which each well contains an individual carbon source as well the redox dye tetrazolium violet. As bacteria grow and oxidize each substrate, …


Estimation Of Bacterial Respiration And Growth Efficiency In The Ross Sea, Antarctica, C. A. Carlson, N. R. Bates, H. W. Ducklow, D. A. Hansell Jan 1999

Estimation Of Bacterial Respiration And Growth Efficiency In The Ross Sea, Antarctica, C. A. Carlson, N. R. Bates, H. W. Ducklow, D. A. Hansell

VIMS Articles

Seawater cultures were conducted in large volume (36 l) gas impermeable tri-laminate bags for the purpose of empirically deriving bacterial growth efficiency (BGE) and carbon conversion factors (CCF) in the south central Ross Sea. This experimental design allowed for concomitant measurements of metabolic reactants (loss of total and dissolved organic carbon [TOC and DOG]) and products (gain of total carbon dioxide [TCO2] and bacterial biomass) to be made from a single incubation vessel. Some previous studies have relied on proxy measurements (e.g. O-2, H-3-thymidine incorporation and cell abundance) to determine BGE and CCF rather than direct carbon measurements. Our experimental …


Bacterial Growth In Experimental Plankton Assemblages And Seawater Cultures From The Phaeocystis Antarctica Bloom In The Ross Sea, Antarctica, H. W. Ducklow, C. Carlson, Walker O. Smith Jr. Jan 1999

Bacterial Growth In Experimental Plankton Assemblages And Seawater Cultures From The Phaeocystis Antarctica Bloom In The Ross Sea, Antarctica, H. W. Ducklow, C. Carlson, Walker O. Smith Jr.

VIMS Articles

A series of seawater culture experiments was carried out during the Phaeocystis antarctica bloom in the Ross Sea polynya (76.5 degrees S, 180 degrees W; November to December 1994 and December 1995 to January 1996) to examine bacterioplankton growth and derive empirical factors for estimating bacterial production rates. Bacterial growth was exponential over 3 to 10 d in all experiments, at rates of ca 0.1 to 0.7 d(-1), even in persistently cold waters (-2 to + 1 degrees C). Growth rates were lower in the early part of the bloom (early to mid-November) and highest during the period of peak …


Research Needs For The Risk Assessment Of Health And Environmental Effects Of Endocrine Disruptors: A Report Of The Us Epa-Sponsored Workshop, Rj Kavlock, Gp Daston, C Derosa, P Fennercrisp, Le Gray, S Kaattari, Et Al Aug 1996

Research Needs For The Risk Assessment Of Health And Environmental Effects Of Endocrine Disruptors: A Report Of The Us Epa-Sponsored Workshop, Rj Kavlock, Gp Daston, C Derosa, P Fennercrisp, Le Gray, S Kaattari, Et Al

VIMS Articles

The hypothesis has been put forward that humans and wildlife species have suffered adverse health effects after exposure to endocrine-disrupting chemicals. Reported adverse effects include declines in populations, increases in cancers, and reduced reproductive function. The U.S. Environmental Protection Agency sponsored a workshop in April 1995 to bring together interested parties in an effort to identify research gaps related to this hypothesis and to establish priorities for future research activities. Approximately 90 invited participants were organized into work groups developed around the principal reported health effects-carcinogenesis, reproductive toxicity, neurotoxicity, and immunotoxicity--as well as along the risk assessment paradigm--hazard identification, dose-response …


Effects Of The June 1995 Freshet On The Main Virginia Tributaries To The Chesapeake Bay, Herbert M. Austin, Christopher F. Bonzek Jan 1996

Effects Of The June 1995 Freshet On The Main Virginia Tributaries To The Chesapeake Bay, Herbert M. Austin, Christopher F. Bonzek

VIMS Articles

Environmental conditions in the Virginian waters of the Chesapeake Bay area during the summerof 1995 have been characterized as a severe drought. This drought was punctuated on 27 June with a headwater (James and Rappahannock River) rain storm that produced a "freshet". Although it did not rain in the Tidewater area of Virginia, surface salinities were depressed by the run-off, and main-stem bottom ox}'gen levels dropped to z.ero in the James and Rappahannock rivers. The effects of the reduced oxygen were apparent on the James River oyster stock, particularly the reduction in spatfall, and to a lesser degree on the …


The Magnitude And Persistence Of Soil No, N2o, Ch4, And Co, Fluxes From Burned Tropical Savanna In Brazil, M Poth, Iris C. Anderson, Et Al Nov 1995

The Magnitude And Persistence Of Soil No, N2o, Ch4, And Co, Fluxes From Burned Tropical Savanna In Brazil, M Poth, Iris C. Anderson, Et Al

VIMS Articles

Among all global ecosystems, tropical savannas are the most severely and extensively affected by anthropogenic burning. Frequency of fire in cerrado,a type of tropical savanna covering 25% of Brazil, is 2 to 4 years. In 1992 we measured soil fluxes of NO, N2O, CH4, and CO2 from cerrado sites that had been burned within the previous 2 days, 30 days, 1 year, and from a control site last burned in 1976. NO and N2O fluxes responded dramatically to fire with the highest fluxes observed from newly burned soils after addition of water. Emissions of N-trace gases after burning were of …


Degradation Kinetics Of Aromatic Organic Solutes Introduced Into A Heterogeneous Aquifer, Wg Macintyre, M Boggs, Cp Antworth, Tb Stauffer Dec 1993

Degradation Kinetics Of Aromatic Organic Solutes Introduced Into A Heterogeneous Aquifer, Wg Macintyre, M Boggs, Cp Antworth, Tb Stauffer

VIMS Articles

Degradation rates of benzene, p-xylene, naphthalene, and o-dichlorobenzene have been measured in a heterogeneous, unconfined aquifer during a pulse injection experiment at Columbus Air Force Base, Columbus, Mississippi. Dissolved oxygen in the pulse plume maintained aerobic conditions. Degradation kinetics calculated from the complete field data set were approximately first order with the following rate constants: benzene, 0.0070 d-1; p-xylene, 0.0107 d-1; naphthalene, 0.0064 d-1; and o-dichlorobenzene, 0.0046 d-1. Reaction rates were also calculated from a near-field subset of the data using a model based on the hydrologic characteristics of the aquifer. Shapes of the degradation rate curves were consistent with …