171,887 research outputs found
Seasonal variation in marine C:N:P stoichiometry: can the composition of seston explain stable Redfield ratios?
Get PDFSeston is suspended particulate organic matter, comprising a mixture of autotrophic, heterotrophic and detrital material. Despite variable proportions of these components, marine seston often exhibits relatively small deviations from the Redfield ratio (C:N:P = 106:16:1). Two time-series from the Norwegian shelf in Skagerrak are used to identify drivers of the seasonal variation in seston elemental ratios. An ordination identified water mass characteristics and bloom dynamics as the most important drivers for determining C:N, while changes in nutrient concentrations and biomass were most important for the C:P and N:P relationships. There is no standardized method for determining the functional composition of seston and the fractions of POC, PON and PP associated with phytoplankton, therefore any such information has to be obtained by indirect means. In this study, a generalized linear model was used to differentiate between the live autotrophic and non-autotrophic sestonic fractions, and for both stations the non-autotrophic fractions dominated with respective annual means of 76 and 55%. This regression model approach builds on assumptions (e.g. constant POC:Chl-a ratio) and the robustness of the estimates were explored with a bootstrap analysis. In addition the autotrophic percentage calculated from the statistical model was compared with estimated phytoplankton carbon, and the two independent estimates of autotrophic percentage were comparable with similar seasonal cycles. The estimated C:nutrient ratios of live autotrophs were, in general, lower than Redfield, while the non-autotrophic C:nutrient ratios were higher than the live autotrophic ratios and above, or close to, the Redfield ratio. This is due to preferential remineralization of nutrients, and the P content mainly governed the difference between the sestonic fractions. Despite the seasonal variability in seston composition and the generally low contribution of autotrophic biomass, the variation observed in the total seston ratios was low compared to the variation found in dissolved and particulate pools. Sestonic C:N:P ratios close to the Redfield ratios should not be used as an indicator of phytoplankton physiological state, but could instead reflect varying contributions of sestonic fractions that sum up to an elemental ratio close to Redfield
Correspondence : Redfield (William) and Engelmann (George), 1854-1855
No full textRedfield to Gray, undate
Correspondence : Redfield (William) and Engelmann (George), 1854-1855
No full textRedfield (William) to Engelmann, 1854-185
Alfred C. Redfield
No full textRedfield is seated at a lab table, looking at a beaker sitting on a tripod stand. There is a doorway behind him to the right.Inscriptions on image and/or album page: Front: "#129" / "Redfield" / "Alfred C" / "'22"Digitized by: MBLWHOI Libraryimage/jpg black and white image reformatted digitalPhotograph
Letter from William Redfield to Heman Norton, 5 September 1827
No full textWilliam Redfield writes from New York City to introduce Alden Partridge and his cadets, who are on a pedestrian excursion to Niagara Falls, to Heman Norton in Rochester, New York.Transcription by Raymond Bouchard. Transcriptions may be subject to error
Front and Side Façade of Depot, Redfield SD, Spink County
No full text35 mm slide, a farming implement and a sign bearing the text "D.H.M. Builders & Equipment [?] Buildings Concrete Work Grain and Livestock Equip. Redfield, S.D. Ph. 472-2550" next to a single-story brick building with a false frontDrawer info: Pennington -Turner; RedfieldEktachrome Slide Spink Co. Redfield Depot C. Sands 16 Sep 79 R
Side Façade of CNW Depot, Redfield SD, Spink County
No full text35 mm slide, a sign bearing the text "D.H.M. Builders & Equipment Buildings Concrete Work Grain and Livestock Equip. Redfield, S. D. Ph. 472-2550" in front of a single-story brick building with two wingsDrawer info: Pennington -Turner; National Register PropertiEktachrome Slide Spink Co. Redfield Depot C. Sands 24 Sep 79 R
Redfield - Beam Walkers;Redfield - Commercial Property;
No full textThis is a 7x5 glass plate of two individuals standing on an elevated steel rafter beam. Text on the beam includes "C" #A70384 SW4". Title(s) by Carpenter, L.385 H86-038 Lester Black Collection Vault 334-417 Box 5 of 8 Glass plates H86-037 Lester Black Collection Mitchell - Mitchell Corn Palace Corn Palace Mitchell 1916 - Scenes of Mitchell Lester Black a carpenter at Redfield helped build barns at State School for Feebled Minded in Redfield, 1920's -385 Building under construction. 3
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