Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 121 - 126 of 126

Full-Text Articles in Physical Sciences and Mathematics

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 …


Phytoplankton Growth Rates In The Ross Sea, Antarctica, Determined By Independent Methods: Temporal Variations, Walker O. Smith Jr., D. M. Nelson, S. Mathot Jan 1999

Phytoplankton Growth Rates In The Ross Sea, Antarctica, Determined By Independent Methods: Temporal Variations, Walker O. Smith Jr., D. M. Nelson, S. Mathot

VIMS Articles

The development of the seasonal phytoplankton bloom in the Ross Sea was studied during two cruises. The first, conducted in November-December 1994, investigated the initiation and rapid growth of the bloom, whereas the second (December 1995-January 1996) concentrated on the bloom's maximum biomass period and the subsequent decline in biomass. Central to the understanding of the controls of growth and the summer decline of the bloom is a quantitative assessment of the growth rate of phytoplankton. Growth rates were estimated over two time scales with different methods. The first estimated daily growth rates from isotopic incorporation under simulated in situ …


Gas Chromatographic Isolation Of Individual Compounds From Complex Matrices For Radiocarbon Dating, Ti Eglinton, Li Alueihare, Je Bauer, Erm Druffel, Ap Mcnichol Jan 1996

Gas Chromatographic Isolation Of Individual Compounds From Complex Matrices For Radiocarbon Dating, Ti Eglinton, Li Alueihare, Je Bauer, Erm Druffel, Ap Mcnichol

VIMS Articles

This paper describes the application of a novel, practical approach for isolation of individual compounds from complex organic matrices for natural abundance radiocarbon measurement. This is achieved through the use of automated preparative capillary gas chromatography (PCGC) to separate and recover sufficient quantities of individual target compounds for C-14 analysis by accelerator mass spectrometry (AMS). We developed and tested this approach using a suite of samples (plant lipids, petroleums) whose ages spanned the C-14 time scale and which contained a variety of compound types (fatty acids, sterols, hydrocarbons), Comparison of individual compound and bulk radiocarbon signatures for the isotopically homogeneous …


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 …


Ocean Biogeochemical Fluxes - New Production And Export Of Organic-Matter From The Upper Ocean, Hw Ducklow Jan 1995

Ocean Biogeochemical Fluxes - New Production And Export Of Organic-Matter From The Upper Ocean, Hw Ducklow

VIMS Articles

Studies of ocean biogeochemical fluxes have been energized in this decade, by the urgency of our need to understand and predict the effects of continued CO2accumulation in the atmosphere, by the global perspectives offered by satellite views of ocean color and related physical fields (McClain et al. 1991; Yoder et al. 1992; Mitchell 1994), and by the successful implementation of the Joint Global Ocean Flux Study (JGOFS; Bowles and Livingston, 1993). In this review, I focus on oceanic new production, originally defined as the fraction of primary production supported by inputs of ‘new’ nitrogen from outside the euphotic …


Investigations Of Inner Continental Shelf Waters Off Lower Chesapeake Bay. Part V. Seasonality Of The Diatom Genus Chaetoceros, Richard A. Mulford Jan 1964

Investigations Of Inner Continental Shelf Waters Off Lower Chesapeake Bay. Part V. Seasonality Of The Diatom Genus Chaetoceros, Richard A. Mulford

VIMS Articles

Twenty-five species of Chaetoceros were taken from monthly samples during one year in the Atlantic Ocean off the Virginia capes. Results indicate the fall-winter period to be the most productive in numbers and species diversity. The Chaetoceros population was primarily a mixture of cold- and warm-water forms, with two species, C. decipiens and C. didymus, being most abundant and widespread. A cyclic seasonal pattern based on past records is suggested for the genus along the east coast of the United States. Seasonality, temperature, and salinity ranges for each species are presented.