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Full-Text Articles in Life Sciences
Photochemical And Microbial Alteration Of Dissolved Organic Matter In Temperate Headwater Streams Associated With Different Land Use, Yuehan Lu, James E. Bauer, Elizabeth A. Canuel, Youhei Yamashita, Randy Chambers, Rudolf Jaffe
Photochemical And Microbial Alteration Of Dissolved Organic Matter In Temperate Headwater Streams Associated With Different Land Use, Yuehan Lu, James E. Bauer, Elizabeth A. Canuel, Youhei Yamashita, Randy Chambers, Rudolf Jaffe
VIMS Articles
Photochemical and microbial transformations of DOM were evaluated in headwater streams draining forested and human-modified lands (pasture, cropland, and urban development) by laboratory incubations. Changes in DOC concentrations, DOC isotopic signatures, and DOM fluorescence properties were measured to assess the amounts, sources, ages, and properties of reactive and refractory DOM under the influence of photochemistry and/or bacteria. DOC in streams draining forest-dominated watersheds was more photoreactive than in streams draining mostly human-modified watersheds, possibly due to greater contributions of terrestrial plant-derived DOC and lower amounts of prior light exposure in forested streams. Overall, the percentage of photoreactive DOC in stream …
Fluid Driven By Tangential Velocity And Shear Stress: Mathematical Analysis, Numerical Experiment, And Implication To Surface Flow, H. S. Tang, L. Z. Zhang, J. P. -Y. Maa, H. Li, C.B. Jiang, R. Hussain
Fluid Driven By Tangential Velocity And Shear Stress: Mathematical Analysis, Numerical Experiment, And Implication To Surface Flow, H. S. Tang, L. Z. Zhang, J. P. -Y. Maa, H. Li, C.B. Jiang, R. Hussain
VIMS Articles
This paper investigates behaviors of flows driven by tangential velocity and shear stress on their boundaries such as solid walls and water surfaces. In a steady flow between two parallel plates with one of them in motion, analytic solutions are the same when a velocity and a shear stress boundary condition are applied on the moving plate. For an unsteady, impulsively started flow, however, analysis shows that solutions for velocity profiles as well as energy transferring and dissipation are different under the two boundary conditions. In an air-water flow, if either a velocity or a stress condition is imposed at …
Microphytobenthos And Benthic Macroalgae Determine Sediment Organic Matter Composition In Shallow Photic Sediments, Ak Hardison, Elizabeth A. Canuel, Iris C. Anderson, C. R. Tobias, B. Veuger, M. N. Waters
Microphytobenthos And Benthic Macroalgae Determine Sediment Organic Matter Composition In Shallow Photic Sediments, Ak Hardison, Elizabeth A. Canuel, Iris C. Anderson, C. R. Tobias, B. Veuger, M. N. Waters
VIMS Articles
Microphytobenthos and benthic macroalgae play an important role in system metabolism within shallow coastal bays. However, their independent and interactive influences on sediment organic matter (SOM) are not well understood. We investigated the influence of macroalgae and microphytobenthos on SOM quantity and quality in an experimental mesocosm system using bulk and molecular level (total hydrolyzable amino acids, THAA; phospholipid linked fatty acids, PLFA; pigment) analyses. Our experiment used an incomplete factorial design made up of two factors, each with two levels: (1) light (ambient vs. dark) and (2) macroalgae (presence vs. absence of live macroalgae). Over the course of the …
Linking Dynamics Of Transport Timescale And Variations Of Hypoxia In The Chesapeake Bay, Bo Hong, Jian Shen
Linking Dynamics Of Transport Timescale And Variations Of Hypoxia In The Chesapeake Bay, Bo Hong, Jian Shen
VIMS Articles
Dissolved oxygen (DO) replenishment in the bottom waters of an estuary depends on physical processes that are significantly influenced by external forcings. The vertical exchange time (VET) is introduced in this study to quantify the physical processes that regulate the DO replenishment in the Chesapeake Bay. A 3-D numerical model was applied to simulate the circulation, VET, and DO. Results indicate that VET is a suitable parameter for evaluating the bottom DO condition over both seasonal and interannual timescales. The VET is negatively correlated with the bottom DO. Hypoxia (DO L-1) will develop in the Bay when VET is greater …
Extratropical Storm Inundation Testbed: Intermodel Comparisons In Scituate, Massachusetts, Changsheng Chen, Et Al., Harry V. Wang
Extratropical Storm Inundation Testbed: Intermodel Comparisons In Scituate, Massachusetts, Changsheng Chen, Et Al., Harry V. Wang
VIMS Articles
The Integrated Ocean Observing System Super-regional Coastal Modeling Testbed had one objective to evaluate the capabilities of three unstructured-grid fully current-wave coupled ocean models (ADCIRC/SWAN, FVCOM/SWAVE, SELFE/WWM) to simulate extratropical storm-induced inundation in the US northeast coastal region. Scituate Harbor (MA) was chosen as the extratropical storm testbed site, and model simulations were made for the 24-27 May 2005 and 17-20 April 2007 (Patriot's Day Storm) nor'easters. For the same unstructured mesh, meteorological forcing, and initial/boundary conditions, intermodel comparisons were made for tidal elevation, surface waves, sea surface elevation, coastal inundation, currents, and volume transport. All three models showed similar …
Longitudinal Variability Of Size-Fractionated N-2 Fixation And Don Release Rates Along 24.5 Degrees N In The Subtropical North Atlantic, Mar Benavides, Deborah A. Bronk, Nona S.R. Agawin, M. Dolores Perez-Hernandez, Alonso Hernandez-Guerra, Javier Aristegui
Longitudinal Variability Of Size-Fractionated N-2 Fixation And Don Release Rates Along 24.5 Degrees N In The Subtropical North Atlantic, Mar Benavides, Deborah A. Bronk, Nona S.R. Agawin, M. Dolores Perez-Hernandez, Alonso Hernandez-Guerra, Javier Aristegui
VIMS Articles
Dinitrogen (N-2) fixation and dissolved organic nitrogen (DON) release rates were measured on fractionated samples (>10 mu m and m) along 24.5 degrees N in the subtropical North Atlantic. Net N-2 fixation rates (N-2 assimilation into biomass) ranged from 0.01 to 0.4 nmol N L-1 h(-1), and DON release rates ranged from 0.001 to 0.09 nmol N L-1 h(-1). DON release represented approximate to 14% and approximate to 23% of >10 mu m and (assimilation into biomass plus DON release), respectively. This implies that by overlooking DON release, N-2 fixation rates are underestimated. Net N-2 fixation rates were higher …
Distribution And Sources Of Organic Matter In Surface Marine Sediments Across The North American Arctic Margin, Miguel A. Goni, Alison E. O'Connor, Zou Zou Kyzyk, Mark B. Yunker, Charles Gobeil, Robie W. Macdonald
Distribution And Sources Of Organic Matter In Surface Marine Sediments Across The North American Arctic Margin, Miguel A. Goni, Alison E. O'Connor, Zou Zou Kyzyk, Mark B. Yunker, Charles Gobeil, Robie W. Macdonald
VIMS Articles
As part of the International Polar Year research program, we conducted a survey of surface marine sediments from box cores along a section extending from the Bering Sea to Davis Strait via the Canadian Archipelago. We used bulk elemental and isotopic compositions, together with biomarkers and principal components analysis, to elucidate the distribution of marine and terrestrial organic matter in different regions of the North American Arctic margin. Marked regional contrasts were observed in organic carbon loadings, with the highest values (1 mg C m(-2) sediment) found in sites along Barrow Canyon and the Chukchi and Bering shelves, all of …
Using Timescales To Interpret Dissolved Oxygen Distributions In The Bottom Waters Of Chesapeake Bay, Jian Shen, B Hong, Ay Kuo
Using Timescales To Interpret Dissolved Oxygen Distributions In The Bottom Waters Of Chesapeake Bay, Jian Shen, B Hong, Ay Kuo
VIMS Articles
A simplified conceptual model based on timescales of gravitational circulation, vertical exchange, and total oxygen consumption rate of the biochemical processes is presented to provide insight into the relationships between estuarine dynamics and bottom water dissolved oxygen (DO). Two dimensionless parameters are introduced to diagnose the relationship between the vertical exchange process and the biochemical DO consumption and the influence of gravitational circulation on replenishment of bottom DO. The relative magnitudes of these timescales provide a linkage between the physical and biochemical processes. The hypoxic and anoxic conditions in deep waters of Chesapeake Bay are successfully interpreted with these three …
Improved Method For Quantifying The Air-Sea Flux Of Volatile And Semi-Volatile Organic Carbon, Ej Hauser, Rm Dickhut, R Falconer, As Wozniak
Improved Method For Quantifying The Air-Sea Flux Of Volatile And Semi-Volatile Organic Carbon, Ej Hauser, Rm Dickhut, R Falconer, As Wozniak
VIMS Articles
A method for quantifying the diffusive air-sea exchange of gaseous organic carbon (OC) was developed. OC compounds were separated into two operational pools-those that were kinetically air limited in diffusion across the air-sea interface and those that were water limited-during simultaneous air/water sampling. The method separates OC compounds into low Henry's law constant (low-H) semivolatile OC (SOC) and high Henry's law constant (high-H) volatile OC (VOC) pools that can be categorized by relating diffusion kinetic parameters to Henry's Law constant. Air limited (low-H; H << similar to 0.1 L atm mol(-1)) compounds were collected in pure water traps and were quantified as dissolved OC, whereas water limited (high-H; H >> similar to 0.1 L atm mol-1) compounds were collected on solid sorbent tubes downstream from the …