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Geomorphologic Controls On The Age Of Particulate Organic Carbon From Small Mountainous And Upland Rivers, El Leithold, Ne Blair, Dw Perkey
Geomorphologic Controls On The Age Of Particulate Organic Carbon From Small Mountainous And Upland Rivers, El Leithold, Ne Blair, Dw Perkey
VIMS Articles
To assess the role that erosion processes play in governing the character of particulate organic carbon (POC) discharged from small mountainous and upland rivers, a suite of watersheds from Oregon, California, and New Zealand was investigated. The rivers share similar geology, tectonic setting, and climate, but have sediment yields that range over 3 orders of magnitude. The (14)C age of the POC loads is highly correlated with sediment yield. Carbon isotope mass balances reveal that the rivers carry bimodal mixtures of modern-plant-and ancient-rock-derived OC. At lower yields, modern plant OC dominates the material delivered to the river by sheetwash and …
Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil
Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil
VIMS Articles
During a 3‐yr study in the Gulf of Mexico, we measured dinitrogen (N2) fixation and nitrogen (N) release by Trichodesmium and compared these rates with water column N demand and the estimated N necessary to support blooms of Karenia brevis, a toxic dinoflagellate that severely affects the West Florida shelf. Net and gross N2 fixation rates were compared in simultaneous incubations using δ15N2 uptake and acetylene reduction, respectively. The difference between net and gross N2 fixation is assumed to be an approximation of the rate of N release. Results demonstrate that Trichodesmium in the Gulf of Mexico are fixing …
Dam Impacts On The Changjiang (Yangtze) River Sediment Discharge To The Sea: The Past 55 Years And After The Three Gorges Dam, Z Yang, H Wang, Y Saito, Jd Milliman, K Xu, S Qiao, G Shi
Dam Impacts On The Changjiang (Yangtze) River Sediment Discharge To The Sea: The Past 55 Years And After The Three Gorges Dam, Z Yang, H Wang, Y Saito, Jd Milliman, K Xu, S Qiao, G Shi
VIMS Articles
In 5 recent years ( 2000 - 2004), the Changjiang ( Yangtze) River has discharged past Datong (600 km from the river mouth) an average of similar to 250 million tons (mt) of sediment per year, a decrease of more than 40% since the 1950s and 1960s, whereas water discharge at Datong has increased slightly. Water and sediment discharge data from the upper, middle, and lower reaches of the river suggest that the reduction of the Changjiang sediment load has occurred in two phases between 1950 and 2002: following the closure of the Danjiangkou Reservoir on the Hanjiang tributary in1968 …
Calculating Shoreline Erosion Potential Using Nearshore Stratigraphy And Sediment Volume: Outer Banks, North Carolina, Jennifer L. Miselis, Jesse E. Mcninch
Calculating Shoreline Erosion Potential Using Nearshore Stratigraphy And Sediment Volume: Outer Banks, North Carolina, Jennifer L. Miselis, Jesse E. Mcninch
VIMS Articles
[1] Despite the acknowledged influence of coastal geological framework on the behavior of beaches and barrier islands and a wealth of geological and bathymetric observations from the inner shelf, quantitatively connecting those observations to shoreline behavior has been difficult. Nearshore geologic and morphologic variability described by recent research is not well represented by conventional geologic parameters, such as mean grain size and shoreface slope, used in most shoreline change models. We propose that total nearshore sediment volume, as calculated to a continuous seismic reflection surface, provides a flexible and robust metric for use in the prediction of shoreline change. This …
Plankton Development And Trophic Transfer In Seawater Enclosures With Nutrients And Phaeocystis Pouchetii Added, J. C. Nejstgaard, M. E. Frischer, P. G. Verity, J. T. Anderson, A. Jacobson, Mj Zirbel, A. Larsen, J. Mrtinez-Martinez, Af. Sazhin, T. Walters, Da Bronk, Sj. Whipple, Sr. Borrett, Bc Patten, Jd Long
Plankton Development And Trophic Transfer In Seawater Enclosures With Nutrients And Phaeocystis Pouchetii Added, J. C. Nejstgaard, M. E. Frischer, P. G. Verity, J. T. Anderson, A. Jacobson, Mj Zirbel, A. Larsen, J. Mrtinez-Martinez, Af. Sazhin, T. Walters, Da Bronk, Sj. Whipple, Sr. Borrett, Bc Patten, Jd Long
VIMS Articles
In high latitude planktonic ecosystems where the prymnesiophyte alga Phaeocystis pouchetii is often the dominant primary producer, its importance in structuring planktonic food webs is well known. In this study we investigated how the base of the planktonic food web responds to a P. pouchetii colony bloom in controlled mesocosm systems with natural water enclosed in situ in a West Norwegian fjord. Similar large (11 m(3)) mesocosm studies were conducted in 2 successive years and the dynamics of various components of the planktonic food web from viruses to mesozooplankton investigated. In 2002 (4 to 24 March), 3 mesocosms comprising a …