Physical Sciences and Mathematics Commons^™

Chemical And Toxicological Characterization Of The Lower Mobjack Bay, York River, Virginia Segment Of The Chesapeake Bay, Morris H. Roberts Jr., Mark A. Richards, Peter F. Delisle

Reports

The Chesapeake Bay segment called Lower Mobjack Bay Lower York River Virginia was found to have insufficient data to characterize in 1999. Therefore this area was selected for a chemical, toxicological, benthic community characterization study of the sediments in 2002. The segment was divided into 3 strata: the lower York River, the Poquoson River, and Back River, each with 4 randomly selected stations. Samples were collected in October 2002 for evaluation of conditions.

There were few significant chemical exceedances of the ER-L or ER-M in the three strata and no toxicologically effects from exposure to sediment samples from any stratum. …

Benthic Algae Control Sediment-Water Column Fluxes Of Organic And Inorganic Nitrogen Compounds In A Temperate Lagoon, Ac Tyler, Kj Mcglathery, Iris C. Anderson

VIMS Articles

Coastal lagoons are a common land-margin feature worldwide and function as an important filter for nutrients entering from the watershed. The shallow nature of lagoons leads to dominance by benthic autotrophs, which can regulate benthic-pelagic coupling. Here we demonstrate that both microalgae and macroalgae are important in controlling dissolved inorganic as well as organic nitrogen (DIN and DON) fluxes between the sediments and the water column. Fluxes of nitrogen (NH4+, NO3-, DON, urea, and dissolved free and combined amino acids [DFAA, DCAA]) and O-2 were measured from October 1998 through August 1999 in sediment cores collected from Hog Island Bay, …

Modeling Sediment Transport In The York River : Final Report, Jerome P.-Y. Maa

Reports

Numerical simulation on the formation of an Estuarine Turbidity Maximum (ETM) is a difficult task because of the incomplete knowledge on cohesive sediment transport. For example, it is difficult to well simulate the erosion process when the bed erosion properties are only poorly known. It is also hard to simulate the settling process when the bulk density and size of suspended sediment flocs are changing with the ambient environments.

Despite of the difficulties, some processes can be parametricalized, even not perfectly, to make the simulation results close to observed. In this project, we demonstrated the possibility of using a constant …

Penetration Of Anthropogenic Carbon Into Organic Particles Of The Deep Ocean, Erm Druffel, Je Bauer, S Griffin, J Hwang

VIMS Articles

] In the late 1980s, bomb C-14 was present in suspended particulate organic carbon (POC) from the North Central Pacific (NCP) and Sargasso Sea ( SS) throughout most of the water column, demonstrating that deep POC had exchanged with atmospheric CO2 in the past 30 years. Upon reoccupation of these sites in 1999 and 2000, respectively, we observed that the delta(13)C values of suspended POC were lower than those measured a decade earlier. This demonstrates that anthropogenic CO2 from fossil fuel and biomass burning has penetrated a major organic matter pool in the deep ocean. Delta(14)C measured in the suspended …

Laboratory Oxide Coatings: Physical Form And Surface Chemistry, Kea U. Duckenfield

Dissertations, Theses, and Masters Projects

The impact of dissolved trace metals on aquatic ecosystems and human health is controlled by sorption, i.e., binding to the surfaces of environmental particles. Since many environmental particles are coated with highly reactive substances, and since discrepancies in trace metal sorption behavior persist between oxides developed in the laboratory and environmental oxide phases, it was hypothesized that the physical form of oxide coatings may influence the chemical properties of the coated particle. Therefore, relationships between the physical forms of several different Fe(III) oxide coatings and the Cu(II) sorption behavior of the coated solids were investigated in comparison with the component …

Controls On The Delivery Of Fluvial Sediment To The Coastal Ocean: The Salinas River, California, Katherine L. Farnsworth

Dissertations, Theses, and Masters Projects

To estimate delivery to the coastal ocean, a global river database was assembled. An estimated 35,000 km3 of freshwater, 4 * 10 6 tonnes of dissolved solids and 18.6 * 106 tonnes of suspended sediment are delivered annually. The global delivery of fluvial water and sediment, both suspended and dissolved, is dominated by Southeast Asia, due to the unique climatic, geologic and geomorphic character of the rivers in this region. Over 30% of the global freshwater and dissolved solid discharge, and an astounding 70% of the suspended sediment originate in this region. The Salinas River, central California, was the focus …

Polycyclic Aromatic Hydrocarbon Sources And Distribution In An Urban Estuary, Shelby E. Walker

Dissertations, Theses, and Masters Projects

As part of the assessment of the potential risk posed by contaminated sediments to the environment and human health, the United States Environmental Protection Agency (USEPA) is developing a set of sediment quality criteria (SQC) that are based on equilibrium partitioning (EqP). While EqP theory has often been used to predict contaminant concentrations within a factor of two for a range of sediment types, substantial deviations from predicted values have also been documented. The objective of this research was to evaluate the influence of PAH source on PAH sediment-pore water partitioning and distribution in sediments. The Elizabeth River is one …

Microbial Dynamics And Biogeochemistry In The North Pacific Subtropical Gyre, Matthew J. Church

Dissertations, Theses, and Masters Projects

The research presented in this dissertation describes the influence of planktonic bacterial growth on upper ocean organic matter dynamics in the North Pacific Subtropical Gyre (NPSG). Examination of the temporal dynamics in dissolved organic matter (DOM) was coupled with investigations that targeted the influence of heterotrophic bacterial production (HBP) on organic matter fluxes in the NPSG. Nine cruises to the Hawaii Ocean Time-series field site Station ALOHA revealed that HBP accounted for a large flux of organic carbon in the upper ocean of the NPSG. HBP was significantly enhanced by sunlight, with photoenhancement of HBP accounting for 3.2 mol C …

Availability Of Humic Nitrogen To Phytoplankton, Jason Holt See

Dissertations, Theses, and Masters Projects

The chemical, physical, and biological factors affecting the bioavailability of humic nitrogen (N) to coastal phytoplankton were examined. Historically, humic substances have largely been considered biologically refractory, and humic-N is though to be unavailable biologically without prior oxidation via photochemical cleavage or remineralization by bacteria. This is due in part to the high aromaticity and low N content of humic substances. This dissertation investigates whether these assumptions are valid, and whether humic substances may be a more important source of N to the coastal phytoplankton community than previously believed. The research consisted of four main parts. First, changes in the …

Relationships Between Watershed Characteristics And Base Flow Nutrient Discharges To Eastern Shore Coastal Lagoons, Virginia, Jennifer Wu Stanhope

Dissertations, Theses, and Masters Projects

No abstract provided.

Transport Of Dissolved Inorganic Carbon From A Tidal Freshwater Marsh To The York River Estuary, Sc Neubauer, Iris C. Anderson

VIMS Articles

The cycling of dissolved inorganic carbon (DIC) and the role of tidal marshes in estuarine DIC dynamics were studied in a Virginia tidal freshwater marsh and adjacent estuary. DIC was measured over diurnal cycles in different seasons in a marsh tidal creek and at the junction of the creek with the adjacent Pamunkey River. In the creek, DIC concentrations around high tide were controlled by the same processes affecting whole-estuary DIC gradients. Near low tide, DIC concentrations were 1.5-5-fold enriched relative to high tide concentrations, indicating an input of DIC from the marsh. Similar patterns (although dampened in magnitude) were …

The Chesapeake Bay : A Synopsis, William J. Hargis Jr.

Reports

No abstract provided.