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Temporal And Spatial Patterns In The Ross Sea: Phytoplankton Biomass, Elemental Composition, Productivity And Growth Rates, Walker O. Smith Jr., David Nelson, Giacomo R. Ditullio, Amy R. Leventer

VIMS Articles

The temporal and spatial patterns of phytoplankton biomass, productivity, and particulate matter composition in the Ross Sea were assessed during cruises in January 1990 and February 1992. Biomass and primary productivity in the southern Ross Sea were greatest during mid-January, with surface chlorophyll concentrations, particulate organic carbon levels, and integrated primary productivity averaging 4.9 Ixg L 'l, 0.54 mg L-•, and 2.63 g C m"• d '•, respectively. Comparable mean concentrations and rates for February were 1.1 Ixg L 'l, 0.29 mg L 'l, and 0.78 g C m '•- d '• (decreases of 76, 46, and 70%, respectively), indicative …

Linking Sediment Transport And Stratigraphy On The Continental Shelf, Pl Wilberg, Da Cacchione, Rw Sternberg, L. Donelson Wright

VIMS Articles

The goal of the shelf sediment dynamics component of STRATAFORM is to link sediment transport processes active on the continental shelf to the formation and preservation of event beds in shelf sediment deposits. An approach combining shelf sediment-transport models with high-resolution measurements of water-column and bed properties over periods from several months to several years allows us to make quantitative estimates of bed modification caused by sediment resuspension during episodic transport events. These modifications include erosion and deposition of bed material, formation of graded storm beds, and changes in small-scale bed surface morphology. The characteristics of the resulting “event bed” …

Utilization And Turnover Of Labile Dissolved Organic Matter By Bacterial Heterotrophs In Eastern North Pacific Surface Waters, J Cherrier, Je Bauer, Erm Druffel

VIMS Articles

Seawater incubation experiments were conducted in June and October 1992 to examine bacterial utilization of labile dissolved organic matter (DOM) in open ocean surface waters of the eastern North Pacific. Natural plankton extract-DOM (PE-DOM) and selected model compounds were added to seawater samples to evaluate bacterial utilization and respiration rates relative to bacterial carbon production rates for the various amendments. PE-DOM always stimulated bacterial production and DOM utilization, and the primary nitrogen source supporting this bacterial production was dissolved organic nitrogen (DON). Utilization of DON during exponential growth was balanced by the production of ammonium for samples amended with PE-DOM. …

Seasonal Variability Of Particulate Organic Radiocarbon In The Northeast Pacific Ocean, Ellen R.M. Druffel, James E. Bauer, Peter M. Williams, Shelia Griffin, David Wolgast

VIMS Articles

We present Delta(14)C measurements of particulate organic carbon (POC) collected on four cruises at our time series site (station M) in the northeast Pacific Ocean. We observe a large gradient with depth in the suspended POC Delta(14)C values (124-160 parts per thousand). These profiles display lower Delta(14)C values (by 20-30 parts per thousand) in samples between 2500 m and the bottom during June 1992 and July 1993 than those during February and October 1992. Values of Delta(14)C in sinking POC from deep-moored sediment trap collections suggest a semiannual trend that displays lower overall Delta(14)C in material collected during periods of …

Calcium Carbonate Sedimentation In The Global Ocean: Linkages Between The Neritic And Pelagic Environments, John D. Milliman, Andre W. Droxler

VIMS Articles

Other than fluvial sediment, calcium carbonate (CaCO3) is the greatest source of sediment in the present-day ocean. Interest in carbonate sedimentation extends beyond geologists because the carbonate system involves biologic and geochemical
processes. Carbonate production, for example, releases CO2 but its accumulation becomes a major sink for inorganic carbon.

Unlike fluvial sediments, modern carbonates accumulate more or less equally in the neritic and pelagic environments. Neritic carbonates (benthic) are characterized by rapid production of (mostly) metastable aragonite and magnesian calcite:pelagic production of (primarily) calcite in the open ocean occurs at much slower rates but overmuch larger areas than does neritic …

Tidal Propagation In Strongly Convergent Channels, Carl T. Friedrichs, David G. Aubrey

VIMS Articles

Simple first‐ and second‐order analytic solutions, which diverge markedly from classical views of cooscillating tides, are derived for tidal propagation in strongly convergent channels. Theoretical predictions compare well with observations from typical examples of shallow, “funnel‐shaped” tidal estuaries. A scaling of the governing equations appropriate to these channels indicates that at first order, gradients in cross‐sectional area dominate velocity gradients in the continuity equation and the friction term dominates acceleration in the momentum equation. Finite amplitude effects, velocity gradients due to wave propagation, and local acceleration enter the equations at second order. Applying this scaling, the first‐order governing equation becomes …

Transport Of Particles Across Continental Shelves, Ca Nittrouer, Ld Wright

VIMS Articles

Transport of particulate material across continental shelves is well demonstrated by the distributions on the seabed and in the water column of geological, chemical, or biological components, whose sources are found farther landward or farther seaward. This paper addresses passive (incapable of swimming) particles and their transport across (not necessarily off) continental shelves during high stands of sea level. Among the general factors that influence across-shelf transport are shelf geometry, latitudinal constraints, and the timescale of interest. Research studies have investigated the physical mechanisms of transport and have made quantitative estimates of mass flux across continental shelves. Important mechanisms include …

Correlation Between Electron Capture Negative Chemical Ionization Mass Spectrometric Fragmentation And Calculated Internal Energies For Polychlorinated Biphenyls, John Greaves, Ellen Harvey, William G. Macintyre

VIMS Articles

Correlations between molecular structure and fragmentation observed in electron capture negative chemical ionization mass spectra (moderator gas = methane) of 49 selected tetrachlorinated, pentachlorinated, and hexachlorinated biphenyls have been investigated by using molecular modeling. The semiempirical general molecular orbital program MOPAC was used to calculate molecular properties for biphenyl and the 209 polychlorinated biphenyls. The mass spectrometric ionization and fragmentation processes were found to be linked to the number of chlorine atoms present on the biphenyl, and to the number of those chlorine atoms in the ortho (2, 2', 6, and 6') positions. The intensity of molecular ions increased with …

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 …

Marine Ecosystem Research At The Weddell Sea Ice Edge: The Ameriez Program, Walker O. Smith Jr., Dl Garrison

VIMS Articles

The explorers and naturalists who first visited Antarctica were struck by the large numbers of whales, seals and seabirds in such a harsh environment (summarized in Everson, 1977). Scientific expeditions in the twentieth century confirmed these observations, and also established that an even greater abundance of many different trophic levels occurred at the ice edge. Hart (1942) noted that phytoplankton were more abundant near the ice edge mad suggested that there was a distinct ice-edge flora, and Marr (1962) noted that krill (Euphausia superba) were concentrated at the interface between pack ice and open water. Routh (1949) observed …

Ancient Channels Of The Susquehanna River Beneath Chesapeake Bay And The Delmarva Peninsula, Steven M. Colman, Jeffrey P. Halka, C. Hobbs, Robert B. Mixon, David S. Foster

VIMS Articles

Three generations of the ancestral Susquehanna River system have been mapped beneath Chesapeake Bay and the southern Delmarva Peninsula. Closely spaced seismic reflection profiles in the bay and boreholes in the bay and on the southern Delmarva Peninsula allow detailed reconstruction of each paleochannel system. The channel systems were formed during glacial low sea-level stands, and each contains a channel-fill sequence that records the subsequent transgression. The trunk channels of each system are 2 to 4 km wide and are incised 30 to SO m into underlying strata; they have irregular longitudinal profiles and very low gradients within the Chesapeake …

Oceanic Dispersion Of Larval Fish And Its Implication For Mortality Estimates - Case-Study Of Walleye Pollock Larvae In Shelikof Strait, Alaska, Suam Kim, Bohyun Bang

VIMS Articles

No abstract provided.

The Formation Of Longitudinal Fronts In A Coastal Plain Estuary, Linda M. Huzzey, John M. Brubaker

VIMS Articles

Longitudinal estuarine fronts, aligned parallel to the axis of the estuary, are characteristic of the York River. Their time scale for genesis and decay is of the order of hours; they are usually located at the inner edge of the shoals or over the main channel. Field measurements have shown marked intratidal differences in density and current speeds across this estuary. These can be correlated with changes in depth and the strength of the advective processes. Differential advection between the channel and shoal regions, when acting upon a constant longitudinal density gradient, is shown to be of sufficient magnitude to …

Late Pleistocene Barrier-Island Sequence Along The Southern Delmarva Peninsula: Implications For Middle Wisconsin Sea Levels, Kenneth Finkelstein, Michael S. Kearney

VIMS Articles

Evidence for a middle Wisconsin sea-level high at or above modern limits along the east coast of the United States has long been controversial. Most reports have been dismissed as poorly dated or lacking unequivocal documentation of a marine transgression. We describe here a 14C-dated, middle Wisconsin transgressive sequence with an extant subaerial barrier facies along the southern Delmarva Peninsula. This sequence indicates that sea levels were near their present position between ca. 23 and 34 ka; it may correlate with other inferred similar-age littoral deposits of the area, and it suggests that the evidence for glacioeustatic fluctuations during the …

Air Chemistry Over The Tropical Forest Of Guyana, Gl Gregory, Rc Harriss, Rw Talbot, Ra Rasmussen, M Garstang, Mo Andrae, Rr Hinton, Et Al

VIMS Articles

No abstract provided.

Consequences Of Sediment Flux: Escape Or Entrapment?, Maynard M. Nichols

VIMS Articles

Estuaries exhibit a full range of flux that extends from escape of sediment into the ocean to complete entrapment and storage within the system. The trapping efficiency of U.S. East Coast estuaries is compared with respect to long-term infilling and present- day flushing velocity , volumetric capacity , and circulatory mixing. It was found that entrapment prevails in many northern estuaries as a consequence of high volumetric capacity , low flushing velocity , and the nearly closed circulation. In many estuaries, channel deepening has reversed the " normal" trend of long-term infilling. Although dredging enhances circulatory entrapment, large-scale ocean dumping …

Geochemistry And Deposition Of Be-7 In River‐Estuarine And Coastal Waters, C. R. Olsen, I. L. Larsen, P. D. Lowry, N. H. Cutshall, Maynard Nichols

VIMS Articles

The atmospheric flux of cosmogenic Be-7 (53.3-day half-life) and the mode of ?Be deposition in river- estuarine and coastal environments have been examined. The atmospheric flux of ?Be commonly sup- ports inventories ranging from 1.0 to 2.0 pCi/cm 2 (1 pCi = 0.037 Bq). Beryllium 7 concentrations in water phase samples, collected across salinity gradients in several estuaries along the eastern coastline of the United States, range from 0.03 to 0.53 pCi/L and primarily reflect variations in Be-7supply and sorption kinetics. The major process controlling the concentration of Be-7 on estuarine suspended particles appears to be the length of time …

Wave Refraction By Warm Core Rings, George R. Mapp, Christopher S. Welch, John C. Munday Jr.

VIMS Articles

No abstract provided.

Mid‐Level Intrusions At The Continental Shelf Edge, Christopher S. Welch

VIMS Articles

Observations across the continental shelf offshore from New Jersey in late summer 1976 show an intrusion of saline water at the mid level of the water column across the shelf edge front, which appears in density only as an offshore thickening of the pycnocline. This internal density field produces horizontal pressure gradient forces within the pycnocline in the onshore direction. These forces, in the linearized equation of motion with a constant eddy viscosity, drive a circulation which resembles a double Ekman spiral for internal pressure vertical distributions which are thin with respect to the Ekman depth. For thick pressure distributions, …

Tracing Kepone Contamination In James Estuary Sediments, Maynard M. Nichols, Norman H. Cutshall

VIMS Articles

The escape of Kepone into the James River estuary, Virginia, for more than nine years produced widespread contamination of the sediments with important ecological consequences. The pollutant extended seaward more than 100 km from its source and contaminated an estimated 31 million tonnes of sediment to depths of more than 60 cm. Kepone spread through the food chain and to every segment of the environment from marshes to the channel floor.

Kepone escaped mainly during high river inflow from a point source in freshwater tributaries. Near the source Kepone is associated with organic material but in the low er estuary …

Enewetak (Eniwetok) Atoll- Aspects Of Nitrogen Cycle On A Coral Reef, K. L. Webb, William D. Dupaul, W. Wiebe, W. Sottile, R. E. Johannes

VIMS Articles

No abstract provided.

Tidal Discharge Asymmetry In A Salt Marsh Drainage System, John D. Boon

VIMS Articles

Tidal discharge and area‐averaged current speed were measured over complete tidal cycles at the entrance to a salt marsh drainage system near Wachapreague, Virginia. A pronounced asymmetry in curves of discharge and current speed through time was observed which can be simulated by a model incorporating semidiurnal tides and “overtides” in conjunction with marsh and channel storage relationships. As a persistent feature in marsh channel flow relationships, the asymmetry, along with an apparent difference in flood and ebb maxima, may have a systematic, long term influence on the net transport of suspended matter entering and leaving natural marshes.

Optimized Measurements Of Discharge And Suspended Sediment Transport In A Salt Marsh Drainage System, John D. Boon

VIMS Articles

Detailed measurements of current speed and suspended sedlment concentration distributions in a channel cross-section of a tidal marsh creek were analyzed. Subsequent sampiing Intervals In time and space were selected to provide acceptable estimates of flood and ebb transport of water and suspended sediment post the cross sectlon. Data from eight 13-hour measurement runs taken at various times of the year seem to favor a net ebb resldual of suspended sedlment transport for the year In question.

A number of environmental factors appear to Influence suspended sediment trons· port in marsh channels.Residual transport of sediment In these systems is, however, …

Groundwater Flow In A Sandy Tidal Beach 2. Two-Dimensional Finite Element Analysis., C. S. Fang, S. N. Wang, W. Harrison

VIMS Articles

Two-dimensional finite element techniques are described that model closely the complicated fluctuations osbserved in the water table of an ocean beach. The use of triangular elements permits the specification of more realistic boundary conditions than the use of line elements in a one-dimensional model. Also, results obtained from the two-dimensional model for the region closet o the ocean compare more favorably with field data than results obtained from the one-dimensional finite element model.

Groundwater Flow In A Sandy Tidal Beach 1. One-Dimensional Finite Element Analysis, W. Harrison, C. S. Fang, S. N. Wang

VIMS Articles

A 31-day time series of observations of beach water table and tidal fluctuations was obtained from 13 wells along a profile perpendicular to the shoreline at Virginia Beach, Virginia. Finite element techniques were applied to solve the one-dimensional, unsteady state, nonlinear equation for groundwater movement. For the finite element analysis, the semi-infinite mass (unconfined aquifer) had to be replaced by a finite mass. The boundary conditions were found from the field data by directly solving the flow equation with a finite difference technique. The finite element method, using the variational principle, provided a reasonable solution and afforded economy in computer …

Estuarine Foraminifera From The Rappahannock River, Virginia, Robert L. Ellison, Maynard M. Nichols

VIMS Articles

Populations of benthonlc foraminifera were studied from 263 samples obtained in 5 collections from the estuary, its tributaries and borderlng marshes

Predictor Equations For Beach Processes And Responses, W. Harrison, N. A. Pore, D. R. Tuck Jr.

VIMS Articles

A stepwise (linear) multiple regression procedure is applied to 11 environmental variables (or predictors) in the beach-ocean-atmosphersey stema t Virginia Beach, Virginia, for the following five predictands: mean longshore current velocity, mean bottom slope in the shoaling-wave zone, average mean grain size in the shoaling-wave zone, and beach deposition and beach erosion on the lower foreshore. Predictors consist of variables related to beach geometry, local water properties, local wind conditions, tidal fluctuations, and wave characteristics The resultant equations are tested against a set of independent data and, with one exception, agree reasonably. It is believed that if the data set …

Possible Late Pleistocene Uplift, Chesapeake Bay Entrance, W. Harrison, Rj Malloy, Ga Rusnak, J Terasmae

VIMS Articles

Paleontological and lithological studies of engineering borings and boring logs subaerial erosion surface of Pliocene (?)-Pleistocene age cuts across clastic sediments of pre-Yorktownian Miocene age in the subsurface and subbottom of the lower Chesapeake Bay area. When the bore-hole data are coupled with the results of subbottom echo profiling and piledriving records, it is possible to construct accurate cross sections of the buried Miocene-Pleistocene contact. The cross sections show "lows" in the erosion surface that may be correlated with the buried channels of the Pleistocene Elizabeth, James, York, and Susquehanna river valleys. Probable channel depths below mean low water at …

Sea-Level And Crustal Movements Along The New England-Acadian Shore, 4,500-3,000 B.P, W. Harrison, C. J. Lyon

VIMS Articles

Remains of three drowned forests have been investigated at Odiorne Point, New Hampshire, and Fort Lawrence and Grand Pre, west-central Nova Scotia. Carbon-14 ages and altitudes below mean tide levels were determined for four in-place stumps of white pine at each locality. Assuming that each dated stump was killed by rising salt water, and that its C14 age represented its true age at death, it was possible to construct curves showing the sequence of submergence and emergence at each site.

A continuous transgression of the sea, approximating 0.31 foot per century, is indicated for the period 4,500-3,200 B.P. This rate …