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- Biological Sciences Peer-Reviewed Articles (19)
- Physical Sciences Peer-Reviewed Articles (13)
- Amazon; carbon cycling; POC; radiocarbon; total CO(2) (1)
- Atlantic Bloom Experiment; Sub-Arctic Pacific; High-Temperature Combustion; Western Bransfield Strait; Time-Series Station; North-Atlantic (1)
- Aurelia aurita (1)
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- Biogeochemical model; ecological model; forecasting; reanalysis; climate projection (1)
- Biogeochemistry; eutrophication; New England (1)
- Black Carbon; Atmospheric Aerosols; Chemical-Composition; United-States; Particulate Matter (1)
- Carbon-Isotope Analysis; Food Webs; Bacteria; Bioavailability; Extraction; Sediments; (1)
- Chesapeake Bay; Pacific-Ocean; Marine-Sediments; Shelf Water; Temporal Variability; Lateral Transport (1)
- Coastal groundwater; oxyanion-forming elements; redox-sensitive metals; submarine groundwater discharge; subterranean estuary (1)
- DOC; DON; DOP; BGE; phototransformation; bacterial bioassays (1)
- Denitrification (1)
- Ecosystem restoration (1)
- Food quality (1)
- Foraminifera (1)
- Groundwater (1)
- Habitat connectivity (1)
- Historical ecology (1)
- Lakes (1)
- Land-use change (1)
- Lipid-Composition; San-Francisco; Carbon; Ocean; Sediments; River; Radiocarbon; Variability; Biomarkers; Delta-C-13 (1)
- Nitrogen (1)
- North Pacific-Ocean; Sargasso Sea; Bomb Radiocarbon; Matter; C-14; Co2; Variability; Delta-C-13; Sediment; Water (1)
- Ocaen (1)
- Organic carbon (1)
- Pacific-Ocean; Sargasso-Sea; Deep-Sea; Carbon; C-14; Water; Variability; Sediments; Seawater; Spectrometry (1)
- Plankton productivity (1)
- Plankton-derived DOM; bacterial growth efficiency; DOC; DON; dissolved free amino acids; dissolved combined amino acids; monosaccharides (1)
- Primary production (1)
Articles 1 - 30 of 31
Full-Text Articles in Physical Sciences and Mathematics
Drivers And Seasonal Variability Of Redox-Sensitive Metal Chemistry In A Shallow Subterranean Estuary, Alison E. O'Connor, Elizabeth A. Canuel, Aaron J. Beck
Drivers And Seasonal Variability Of Redox-Sensitive Metal Chemistry In A Shallow Subterranean Estuary, Alison E. O'Connor, Elizabeth A. Canuel, Aaron J. Beck
VIMS Articles
The subterranean estuary (STE) has been historically defined in terms of the mixing of saline and fresh water, in an analogy to surface estuaries. However, redox gradients are also a defining characteristic of the STE and influence its role as a source or sink for metals in the environment. Approaching the STE from a redox-focused biogeochemical perspective (e.g., considering the role of microbial respiration and availability of organic matter) provides the ability to quantify drivers of metal transport across spatial and temporal scales. This study measured the groundwater composition of a shallow STE over 2 years and used multiple linear …
Nutrient Function Over Form: Organic And Inorganic Nitrogen Additions Have Similar Effects On Lake Phytoplankton Nutrient Limitation, Sabrina N. Volponi, Heather L. Wander, (...), Brian S. Kim, Et Al
Nutrient Function Over Form: Organic And Inorganic Nitrogen Additions Have Similar Effects On Lake Phytoplankton Nutrient Limitation, Sabrina N. Volponi, Heather L. Wander, (...), Brian S. Kim, Et Al
VIMS Articles
The concentration of dissolved organic nitrogen (DON) is increasing in many northern hemisphere lakes, yet its use by phytoplankton and fate in the environment seldom have been quantified. We conducted 1 week, insitu, microcosm incubations across 25 lakes in northeastern North America to understand how DON, dissolved norganic nitrogen (DIN), and dissolved inorganic phosphorus (P) affected phytoplankton biomass. In addition,we tested whether lakes were limited by single macronutrients (N or P) or colimited by both. Phytoplankton biomass in 80% of lakes responded similarly to DON and DIN additions. Of the lakes where N form produced differential responses, the majority of …
Riverine Carbon Cycling Over The Past Century In The Mid-Atlantic Region Of The United States, Yuanzi Yao, Hanqin Tian, Shufen Pan, Raymond G. Najjar, Marjorie A.M. Friedrichs, Et Al
Riverine Carbon Cycling Over The Past Century In The Mid-Atlantic Region Of The United States, Yuanzi Yao, Hanqin Tian, Shufen Pan, Raymond G. Najjar, Marjorie A.M. Friedrichs, Et Al
VIMS Articles
Rivers are an important component of the terrestrial-aquatic ocean continuum as they serve as a conduit for transporting carbon from the land to the coastal ocean. It is essential to track the fate of this carbon, including how much carbon is buried in the riverbed, outgassed to the atmosphere, and exported to the ocean. However, it is often difficult to quantify these carbon transport processes on the watershed scale because observational data obtained by field surveys can only be used to estimate the magnitude of these processes at distinct points. In this study, we used a coupled terrestrial-aquatic ecosystem model …
Estuaries As Filters For Riverine Microplastics: Simulations In A Large, Coastal-Plain Estuary, Alexander G. Lopez, Raymond G. Najjar, Marjorie A.M. Friedrichs, Michael A. Hickner, Denice H. Wardrop
Estuaries As Filters For Riverine Microplastics: Simulations In A Large, Coastal-Plain Estuary, Alexander G. Lopez, Raymond G. Najjar, Marjorie A.M. Friedrichs, Michael A. Hickner, Denice H. Wardrop
VIMS Articles
Public awareness of microplastics and their widespread presence throughout most bodies of water are increasingly documented. The accumulation of microplastics in the ocean, however, appears to be far less than their riverine inputs, suggesting that there is a “missing sink” of plastics in the ocean. Estuaries have long been recognized as filters for riverine material in marine biogeochemical budgets. Here we use a model of estuarine microplastic transport to test the hypothesis that the Chesapeake Bay, a large coastal-plain estuary in eastern North America, is a potentially large filter, or “sink,” of riverine microplastics. The 1-year composite simulation, which tracks …
Relative Impacts Of Global Changes And Regional Watershed Changes On The Inorganic Carbon Balance Of The Chesapeake Bay, Pierre St-Laurent, Marjorie A.M. Friedrichs, Raymond G. Najjar, Elizabeth Shadwick, Hanquin Tian, Yuanzhi Yao
Relative Impacts Of Global Changes And Regional Watershed Changes On The Inorganic Carbon Balance Of The Chesapeake Bay, Pierre St-Laurent, Marjorie A.M. Friedrichs, Raymond G. Najjar, Elizabeth Shadwick, Hanquin Tian, Yuanzhi Yao
VIMS Articles
The Chesapeake Bay is a large coastal-plain estuary that has experienced considerable anthropogenic changeover the past century. At the regional scale, land-use change has doubled the nutrient input from rivers and led to an increase in riverine carbon and alkalinity. The bay has also experienced global changes, including the rise of atmospheric temperature and CO2. Here we seek to understand the relative impact of these changes on the inorganic carbon balance of the bay between the early 1900s and the early 2000s. We use a linked land–estuarine–ocean modeling system that includes both inorganic and organic carbon and nitrogen cycling. Sensitivity …
Seasonal And Spatial Variation In The Location And Reactivity Of A Nitrate‐Contaminated Groundwater Discharge Zone In A Lakebed, Rl Smith, Da Repert, Dl Stoliker, Db Kent, Bk Song, Et Al
Seasonal And Spatial Variation In The Location And Reactivity Of A Nitrate‐Contaminated Groundwater Discharge Zone In A Lakebed, Rl Smith, Da Repert, Dl Stoliker, Db Kent, Bk Song, Et Al
VIMS Articles
Groundwater discharge delivering anthropogenic N from surrounding watersheds can impact lake nutrient budgets. However, upgradient groundwater processes and changing dynamics in N biogeochemistry at the groundwater‐lake interface are complex. In this study, seasonal water‐level variations in a groundwater flow‐through lake altered discharge patterns of a wastewater‐derived groundwater contaminant plume, thereby affecting biogeochemical processes controlling N transport. Pore water collected 15 cm under the lakebed along transects perpendicular to shore varied from oxic to anoxic with increasing nitrate concentrations (10–75 μM) and corresponding gradients in nitrite and nitrous oxide. Pore water depth profiles of nitrate concentrations and stable isotopic compositions largely …
Advancing Marine Biogeochemical And Ecosystem Reanalyses And Forecasts As Tools For Monitoring And Managing Ecosystem Health, K Fennel, M Gehlen, P Brasseur, Cw Brown, C Ciavatta, G Cossarini, A Crise, Ca Edwards, D Ford, Marjorie A.M. Friedrichs, Et Al
Advancing Marine Biogeochemical And Ecosystem Reanalyses And Forecasts As Tools For Monitoring And Managing Ecosystem Health, K Fennel, M Gehlen, P Brasseur, Cw Brown, C Ciavatta, G Cossarini, A Crise, Ca Edwards, D Ford, Marjorie A.M. Friedrichs, Et Al
VIMS Articles
Ocean ecosystems are subject to a multitude of stressors, including changes in ocean physics and biogeochemistry, and direct anthropogenic influences. Implementation of protective and adaptive measures for ocean ecosystems requires a combination of ocean observations with analysis and prediction tools. These can guide assessments of the current state of ocean ecosystems, elucidate ongoing trends and shifts, and anticipate impacts of climate change and management policies. Analysis and prediction tools are defined here as ocean circulation models that are coupled to biogeochemical or ecological models. The range of potential applications for these systems is broad, ranging from reanalyses for the assessment …
Ocean Acidification Compromises A Planktic Calcifier With Implications For Global Carbon Cycling, Cv Davis, Emily B. Rivest, Et Al
Ocean Acidification Compromises A Planktic Calcifier With Implications For Global Carbon Cycling, Cv Davis, Emily B. Rivest, Et Al
VIMS Articles
Anthropogenically-forced changes in ocean chemistry at both the global and regional scale have the potential to negatively impact calcifying plankton, which play a key role in ecosystem functioning and marine carbon cycling. We cultured a globally important calcifying marine plankter (the foraminifer, Globigerina bulloides) under an ecologically relevant range of seawater pH (7.5 to 8.3 total scale). Multiple metrics of calcification and physiological performance varied with pH. At pH > 8.0, increased calcification occurred without a concomitant rise in respiration rates. However, as pH declined from 8.0 to 7.5, calcification and oxygen consumption both decreased, suggesting a reduced ability to precipitate …
Primary Production In The Delta: Then And Now, James E. Cloern, April Robinson, (...), Elizabeth A. Canuel, Et Al
Primary Production In The Delta: Then And Now, James E. Cloern, April Robinson, (...), Elizabeth A. Canuel, Et Al
VIMS Articles
To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical …
Regression Modeling Of The North East Atlantic Spring Bloom Suggests Previously Unrecognized Biological Roles For V And Mo, Nj Klein, Aj Beck, Da Hutchins, Sa Sanudo-Wilhelmy
Regression Modeling Of The North East Atlantic Spring Bloom Suggests Previously Unrecognized Biological Roles For V And Mo, Nj Klein, Aj Beck, Da Hutchins, Sa Sanudo-Wilhelmy
VIMS Articles
In order to identify the biogeochemical parameters controlling pCO(2), total chlorophyll a, and dimethyl sulfide (DMS) concentrations during the North East Atlantic Spring Bloom (NASB), we used previously unpublished particulate and dissolved elemental concentrations to construct several linear regression models; first by hypothesis testing, and then with exhaustive stepwise linear regression followed by leave-one-out cross-validation. The field data was obtained along a latitudinal transect from the Azores Islands to the North Atlantic, and best-fit models (determined by lowest predictive error) of up to three variables are presented. Total chlorophyll a is predicted best by biomass (POC, PON) parameters and by …
Impact Of Diatom-Diazotroph Associations On Carbon Export In The Amazon River Plume, Ly Yeung, Wm Berelsen, Et Al, Deborah K. Steinberg, Et Al
Impact Of Diatom-Diazotroph Associations On Carbon Export In The Amazon River Plume, Ly Yeung, Wm Berelsen, Et Al, Deborah K. Steinberg, Et Al
VIMS Articles
Offshore tropical river plumes are associated with areas of high N-2 fixation (diazotrophy) and biological carbon drawdown. Episodic blooms of the diatom Hemiaulus hauckii and its diazotrophic cyanobacterial symbiont Richelia intracellularis are believed to dominate that carbon drawdown, but the mechanism is not well understood. We report primary productivity associated with blooms of these diatom-diazotroph assemblages (DDAs) in the offshore plume of the Amazon River using simultaneous measurements of O-2/Ar ratios and the triple-isotope composition of dissolved O-2. In these blooms, we observe peaks in net community productivity, but relatively small changes in gross primary productivity, suggesting that DDA blooms …
Salt Marsh Ecosystem Biogeochemical Responses To Nutrient Enrichment: A Paired N-15 Tracer Study, Dc Drake, Bj Peterson, Et Al, Le Lemay, Et Al
Salt Marsh Ecosystem Biogeochemical Responses To Nutrient Enrichment: A Paired N-15 Tracer Study, Dc Drake, Bj Peterson, Et Al, Le Lemay, Et Al
VIMS Articles
We compared processing and fate of dissolved NO3- in two New England salt marsh ecosystems, one receiving natural flood tide concentrations of similar to 1-4 mu mol NO3-/L and the other receiving experimentally fertilized flood tides containing similar to 70-100 mu mol NO3-/L. We conducted simultaneous (NO3-)-N-15 (isotope) tracer additions from 23 to 28 July 2005 in the reference (8.4 ha) and fertilized (12.4 ha) systems to compare N dynamics and fate. Two full tidal cycles were intensively studied during the paired tracer additions. Resulting mass balances showed that essentially 100% (0.48-0.61 mol NO3-N.ha(-1).h(-1)) of incoming NO3- was assimilated, dissimilated, …
Technical Note: Molecular Characterization Of Aerosol-Derived Water Soluble Organic Carbon Using Ultrahigh Resolution Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, As Wosniak, Je Bauer, Rl Sleighter, Rm Dickhut, Pg Hatcher
Technical Note: Molecular Characterization Of Aerosol-Derived Water Soluble Organic Carbon Using Ultrahigh Resolution Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, As Wosniak, Je Bauer, Rl Sleighter, Rm Dickhut, Pg Hatcher
VIMS Articles
Despite the acknowledged relevance of aerosol-derived water-soluble organic carbon (WSOC) to climate and biogeochemical cycling, characterization of aerosol WSOC has been limited. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) was utilized in this study to provide detailed molecular level characterization of the hi(,h molecular weight (HMW; m/z>223) component of aerosol-derived WSOC collected from rural sites in Virginia and New York, USA. More than 3000 peaks were detected by ESI FT-ICR MS within a m/z range of 223-600 for each sample. Approximately 86% (Virginia) and 78% (New York) of these peaks were assigned molecular formulas …
Dissolved And Particulate Organic Matter Source-Age Characterization In The Upper And Lower Chesapeake Bay: A Combined Isotope And Biochemical Approach, An Loh, Je Bauer, Ea Canuel
Dissolved And Particulate Organic Matter Source-Age Characterization In The Upper And Lower Chesapeake Bay: A Combined Isotope And Biochemical Approach, An Loh, Je Bauer, Ea Canuel
VIMS Articles
In order to characterize the sources and ages of organic matter contributing to river and estuarine outflow waters, the present study investigated Delta C-14 and delta C-13 signatures of the major operationally defined biochemical classes of ultrafiltered dissolved organic matter (UDOM) in conjunction with lipid biomarker and elemental compositions of UDOM and suspended particulate organic matter (POM) in the Chesapeake Bay. Freshwater (Susquehanna River) UDOM was dominated by a molecularly uncharacterized (MUC) fraction, followed by total carbohydrate (TCHO), total hydrolysable amino acid (THAA) and total lipid (TLE) components. In contrast, UDOM at the bay mouth (salinity similar to 22-24) was …
Bioreactivity Of Estuarine Dissolved Organic Matter: A Combined Geochemical And Microbiological Approach, Sl Mccallister, Je Bauer, Elizabeth A. Canuel
Bioreactivity Of Estuarine Dissolved Organic Matter: A Combined Geochemical And Microbiological Approach, Sl Mccallister, Je Bauer, Elizabeth A. Canuel
VIMS Articles
An integrated multidisciplinary study utilizing geochemical and microbial ecological approaches was conducted to characterize the origins, chemical nature, and quantities of dissolved and particulate organic matter (OM) utilized by heterotrophic bacteria in a temperate estuary. C: N, stable isotope (delta C-13), and lipid biomarker analyses revealed differences in the inferred reactivity of autochthonous versus allochthonous OM sources. Isotopic comparison of OM size fractions and bacterial nucleic acids suggests that high-molecular-weight dissolved OM (DOM) is consistently linked to bacterial biomass synthesis along the estuarine salinity gradient. Polyunsaturated fatty acids (as percent of total fatty acids, FA) were a reliable predictor of …
Effects Of Sunlight On Decomposition Of Estuarine Dissolved Organic C, N And P And Bacterial Metabolism, Sl Mccallister, Je Bauer, J Kelly, Hw Ducklow
Effects Of Sunlight On Decomposition Of Estuarine Dissolved Organic C, N And P And Bacterial Metabolism, Sl Mccallister, Je Bauer, J Kelly, Hw Ducklow
VIMS Articles
The effects of natural sunlight and microbial decomposition on DOC, DON, and DOP were investigated along the salinity gradient of a temperate coastal plain estuary. The impact of sunlight-irradiated DOM on bacterial properties (bacterial abundance, production, bacterial growth efficiency [BGE]) was also followed. Surface-water light levels resulted in no detectable abiotic production of NH4+ or PO43- or loss of DOC. Bacterial decomposition of DOC was enhanced by 27 to 200 % in irradiated relative to dark treatments. There was, however, no corresponding enhancement in DON and DOP remineralization. Significant differences in bacterial decomposition of light-exposed DOC were frequently observed following …
Input Of Particulate Organic And Dissolved Inorganic Carbon From The Amazon To The Atlantic Ocean, Erm Druffel, Je Bauer, S Griffin
Input Of Particulate Organic And Dissolved Inorganic Carbon From The Amazon To The Atlantic Ocean, Erm Druffel, Je Bauer, S Griffin
VIMS Articles
We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC D 14 C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC delta(13)C signature of the river end-member (-11%) demonstrates that about half of …
Bacterial Utilization Of Transient Plankton-Derived Dissolved Organic Carbon And Nitrogen Inputs In Surface Ocean Waters, J Cherrier, Je Bauer
Bacterial Utilization Of Transient Plankton-Derived Dissolved Organic Carbon And Nitrogen Inputs In Surface Ocean Waters, J Cherrier, Je Bauer
VIMS Articles
The majority of bacterial growth and respiration in the upper ocean is thought to result from coupling between microheterotrophic populations and the reactive soluble components of planktonic primary and secondary production. However, we know little about the potential turnover of these components and the concomitant growth of bacteria under conditions of intermittent or transient inputs of natural dissolved organic matter (DOM) compared to quasi-steady state, low DOM conditions. The present study evaluated the short-term (similar to3 d) rates and net extents of utilization (as measured losses) of selected constituents of plankton-derived DOM (DOMPD) by indigenous bacterioplankton populations in eastern North …
High Rates Of Ammonium Recycling Drive Phytoplankton Productivity In The Offshore Mississippi River Plume, B Wawrik, Jh Paul, Da Bronk, Et Al
High Rates Of Ammonium Recycling Drive Phytoplankton Productivity In The Offshore Mississippi River Plume, B Wawrik, Jh Paul, Da Bronk, Et Al
VIMS Articles
As part of an integrated study of the regulation of carbon fixation in the offshore Mississippi River plume, we measured the rates of N-15-labeled ammonium and nitrate uptake in the surface plume waters from offshore to nearshore along the plume axis towards the Mississippi Delta. Concentrations of nitrate in the plume ranged from 0.19 to 2.5 muM with the highest concentrations primarily in the shoreward stations, while ammonium ranged from 0.17 to 0.44 muM, showing little spatial variability. Rates of ammonium uptake ranged from 16.5 to 260 nM h(-1), and showed a strong trend of increasing values from offshore towards …
Benthic Algae Control Sediment-Water Column Fluxes Of Organic And Inorganic Nitrogen Compounds In A Temperate Lagoon, Ac Tyler, Kj Mcglathery, Iris C. Anderson
Benthic Algae Control Sediment-Water Column Fluxes Of Organic And Inorganic Nitrogen Compounds In A Temperate Lagoon, Ac Tyler, Kj Mcglathery, Iris C. Anderson
VIMS Articles
Coastal lagoons are a common land-margin feature worldwide and function as an important filter for nutrients entering from the watershed. The shallow nature of lagoons leads to dominance by benthic autotrophs, which can regulate benthic-pelagic coupling. Here we demonstrate that both microalgae and macroalgae are important in controlling dissolved inorganic as well as organic nitrogen (DIN and DON) fluxes between the sediments and the water column. Fluxes of nitrogen (NH4+, NO3-, DON, urea, and dissolved free and combined amino acids [DFAA, DCAA]) and O-2 were measured from October 1998 through August 1999 in sediment cores collected from Hog Island Bay, …
Penetration Of Anthropogenic Carbon Into Organic Particles Of The Deep Ocean, Erm Druffel, Je Bauer, S Griffin, J Hwang
Penetration Of Anthropogenic Carbon Into Organic Particles Of The Deep Ocean, Erm Druffel, Je Bauer, S Griffin, J Hwang
VIMS Articles
] In the late 1980s, bomb C-14 was present in suspended particulate organic carbon (POC) from the North Central Pacific (NCP) and Sargasso Sea ( SS) throughout most of the water column, demonstrating that deep POC had exchanged with atmospheric CO2 in the past 30 years. Upon reoccupation of these sites in 1999 and 2000, respectively, we observed that the delta(13)C values of suspended POC were lower than those measured a decade earlier. This demonstrates that anthropogenic CO2 from fossil fuel and biomass burning has penetrated a major organic matter pool in the deep ocean. Delta(14)C measured in the suspended …
Transport Of Dissolved Inorganic Carbon From A Tidal Freshwater Marsh To The York River Estuary, Sc Neubauer, Iris C. Anderson
Transport Of Dissolved Inorganic Carbon From A Tidal Freshwater Marsh To The York River Estuary, Sc Neubauer, Iris C. Anderson
VIMS Articles
The cycling of dissolved inorganic carbon (DIC) and the role of tidal marshes in estuarine DIC dynamics were studied in a Virginia tidal freshwater marsh and adjacent estuary. DIC was measured over diurnal cycles in different seasons in a marsh tidal creek and at the junction of the creek with the adjacent Pamunkey River. In the creek, DIC concentrations around high tide were controlled by the same processes affecting whole-estuary DIC gradients. Near low tide, DIC concentrations were 1.5-5-fold enriched relative to high tide concentrations, indicating an input of DIC from the marsh. Similar patterns (although dampened in magnitude) were …
Stable Carbon And Nitrogen Isotope Composition Of Aquatic And Terrestrial Plants Of The San Francisco Bay Estuarine System, Je Cloern, Elizabeth A. Canuel, D Harris
Stable Carbon And Nitrogen Isotope Composition Of Aquatic And Terrestrial Plants Of The San Francisco Bay Estuarine System, Je Cloern, Elizabeth A. Canuel, D Harris
VIMS Articles
We report measurements of seasonal variability in the C-N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C-N isotopes can be used as biomarkers for tracing the origins of organic matter in this river-marsh-estuary complex. Variability of delta(130)C and delta(15)N was high (similar to5-10parts per thousand) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles …
Tracking The Fate Of A High Concentration Groundwater Nitrate Plume Through A Fringing Marsh: A Combined Groundwater Tracer And In Situ Isotope Enrichment Study, Cr Tobias, Sa Macko, Iris C. Anderson, Elizabeth A. Canuel, Jw Harvey
Tracking The Fate Of A High Concentration Groundwater Nitrate Plume Through A Fringing Marsh: A Combined Groundwater Tracer And In Situ Isotope Enrichment Study, Cr Tobias, Sa Macko, Iris C. Anderson, Elizabeth A. Canuel, Jw Harvey
VIMS Articles
A groundwater plume enriched in (15)NO(3)(-) was created upgradient of a mesohaline salt marsh. By measuring the changes in concentration and isotopic enrichment of NO(3)(-), N(2)O, N(2), NH(4)(+), and particulate organic nitrogen (PON) during plume transport through the marsh, in situ rates of dissimilatory nitrate reduction to ammonium (DNRA) and denitrification (DNF) were estimated, as well as N storage in the reduced N pools. For groundwater discharge within the top 10 cm of marsh, NO(3)(-) removal was 90% complete within the 50 cm of marsh nearest the upland border. The peak NO(3)(-) loss rate from the plume ranged from 208 …
Sources And Cycling Of Dissolved And Particulate Organic Radiocarbon In The Northwest Atlantic Continental Margin, Je Bauer, Erm Druffel, Dm Wolgast, S Griffin
Sources And Cycling Of Dissolved And Particulate Organic Radiocarbon In The Northwest Atlantic Continental Margin, Je Bauer, Erm Druffel, Dm Wolgast, S Griffin
VIMS Articles
Continental shelves and slopes are productive and dynamic ocean margin systems that also regulate the fluxes of terrestrial, riverine, and estuarine materials between the continents and oceans. In order to evaluate the ages, potential sources, and transformations of organic matter in an ocean margin system, we measured the radiocarbon (Delta (14)C and delta (13)C distributions of total dissolved organic carbon (DOC), suspended particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in waters of the Middle Atlantic Bight (MAB) continental shelf and slope in April-May 1994. The Delta (14)C of DOC was greatest (as high as -39 parts per thousand) …
Quantifying Groundwater Discharge Through Fringing Wetlands To Estuaries: Seasonal Variability, Methods Comparison, And Implications For Wetland-Estuary Exchange, Cr Tobias, Jw Harvey, Iris C. Anderson
Quantifying Groundwater Discharge Through Fringing Wetlands To Estuaries: Seasonal Variability, Methods Comparison, And Implications For Wetland-Estuary Exchange, Cr Tobias, Jw Harvey, Iris C. Anderson
VIMS Articles
Because groundwater discharge along coastal shorelines is often concentrated in zones inhabited by fringing wetlands, accurately estimating discharge is essential for understanding its effect on the function and maintenance of these ecosystems. Most previous estimates of groundwater discharge to coastal wetlands have been temporally limited and have used only a single approach to estimate discharge. Furthermore, groundwater input has not been considered as a major mechanism controlling pore-water flushing. We estimated seasonally varying groundwater discharge into a fringing estuarine wetland using three independent methods (Darcy's Law, salt balance, and Br- tracer). Seasonal patterns of discharge predicted by both Darcy's Law …
Modeling Distinct Vertical Biogeochemical Structure Of The Black Sea: Dynamical Coupling Of The Oxic, Suboxic, And Anoxic Layers, T Oguz, Hw Ducklow, P Malanotte-Rizzoli
Modeling Distinct Vertical Biogeochemical Structure Of The Black Sea: Dynamical Coupling Of The Oxic, Suboxic, And Anoxic Layers, T Oguz, Hw Ducklow, P Malanotte-Rizzoli
VIMS Articles
A one-dimensional, vertically resolved, physical-biogeochemical model is used to provide a unified representation of the dynamically coupled oxic-suboxic-anoxic system for the interior Black Sea. The model relates the annual cycle of plankton production in the form of a series of successive phytoplankton, mesozooplankton, and higher consumer blooms to organic matter generation and to the remineralization-ammonification-nitrification-dentrification chain of the nitrogen cycle as well as to anaerobic sulfide oxidation in the suboxic-anoxic interface zone. The simulations indicate that oxygen consumption during remineralixation and nitrification, together with a lack of ventilation of subsurface waters due to the presence of strong stratification, are the …
Radiocarbon Distributions In Southern Ocean Dissolved And Particulate Organic Matter, Erm Druffel, Je Bauer
Radiocarbon Distributions In Southern Ocean Dissolved And Particulate Organic Matter, Erm Druffel, Je Bauer
VIMS Articles
Dissolved organic carbon (DOC) is the largest actively exchanging pool of organic carbon in the ocean, yet its sources and sinks are not well constrained. The average C-14 ages of DOC in the deep N. Atlantic and N. Pacific Oceans are 4,000 [Bauer et al., 1992; Druffel et al., 1992] and 6,000 years [Williams and Druffel, 1987], respectively, and represent the beginning and end of the deep ocean conveyor [Broecker, 1991]. Here we report that the deep Southern Ocean DOC has a C-14 age (5,600 y) much closer to that of the deep N. Pacific, but its concentration in seawater …
A Stable Isotopic Study To Determine Carbon And Nitrogen Cycling In A Disturbed Southern Californian Forest Ecosystem, S Korontzi, Sa Macko, Iris C. Anderson
A Stable Isotopic Study To Determine Carbon And Nitrogen Cycling In A Disturbed Southern Californian Forest Ecosystem, S Korontzi, Sa Macko, Iris C. Anderson
VIMS Articles
This study utilized isotope analyses to contrast nitrogen and carbon dynamics at four sites located along an air pollution gradient in the San Bernardino National Forest in southern California. Natural N-15 and C-13 abundances along with nutritional and edaphic properties were determined in soil, litter, and vegetation samples. Mean bulk nitrogen delta(15)N values of soil and vegetation at Camp Paivika (CP), the most polluted site, were at least 1.7 parts per thousand more enriched than the other, less polluted sites. Mean soil delta(15)NH(4)(+) was also significantly enriched in N-15 at CP compared to Barton Flats (BF), the least polluted site, …
Radiocarbon In Marine Bacteria: Evidence For The Ages Of Assimilated Carbon, J Cherrier, Je Bauer, Et Al
Radiocarbon In Marine Bacteria: Evidence For The Ages Of Assimilated Carbon, J Cherrier, Je Bauer, Et Al
VIMS Articles
It is generally accepted that marine bacteria utilize labile, recently produced components of bulk dissolved organic matter. This interpretation is based largely on indirect measurements using model compounds and plankton-derived organic matter. Here, we present an assessment of the relative proportions of modem and older dissolved organic carbon (DOC) utilized by marine bacteria. Bacterial nucleic acids were collected from both estuarine (Santa Rosa Sound, FL) and open-ocean (eastern North Pacific) sites, and the natural radiocarbon signatures of the nucleic acid carbon in both systems were determined. Bacterial nucleic acids from Santa Rosa Sound were significantly enriched in radiocarbon with respect …