Acoustical Estimates of Subsurface Bubble Densities in the Open Ocean and Coastal Waters

1988 ◽  
pp. 225-236 ◽  
Author(s):  
Suzanne T. McDaniel
Keyword(s):  
Coastal Waters ◽  
Open Ocean

scholarly journals Carbon dynamics and CO<sub>2</sub> air-sea exchanges in the eutrophied coastal waters of the Southern Bight of the North Sea: a modelling study

2004 ◽  
Vol 1 (2) ◽  
pp. 147-157 ◽  
Author(s):  
N. Gypens ◽  
C. Lancelot ◽  
A. V. Borges
Keyword(s):  
Surface Water ◽  
Coastal Zone ◽  
North Sea ◽  
Coastal Waters ◽  
Co2 Flux ◽  
Open Ocean ◽  
Atmospheric Co2 ◽  
Southern Bight ◽  
The North ◽  
The North Sea

Abstract. A description of the carbonate system has been incorporated in the MIRO biogeochemical model to investigate the contribution of diatom and Phaeocystis blooms to the seasonal dynamics of air-sea CO2 exchanges in the Eastern Channel and Southern Bight of the North Sea, with focus on the eutrophied Belgian coastal waters. For this application, the model was implemented in a simplified three-box representation of the hydrodynamics with the open ocean boundary box ‘Western English Channel’ (WCH) and the ‘French Coastal Zone’ (FCZ) and ‘Belgian Coastal Zone’ (BCZ) boxes receiving carbon and nutrients from the rivers Seine and Scheldt, respectively. Results were obtained by running the model for the 1996–1999 period. The simulated partial pressures of CO2 (pCO2) were successfully compared with data recorded over the same period in the central BCZ at station 330 (51°26.05′ N; 002°48.50′ E). Budget calculations based on model simulations of carbon flow rates indicated for BCZ a low annual sink of atmospheric CO2 (−0.17 mol C m-2 y-1). On the opposite, surface water pCO2 in WCH was estimated to be at annual equilibrium with respect to atmospheric CO2. The relative contribution of biological, chemical and physical processes to the modelled seasonal variability of pCO2 in BCZ was further explored by running model scenarios with separate closures of biological activities and/or river inputs of carbon. The suppression of biological processes reversed direction of the CO2 flux in BCZ that became, on an annual scale, a significant source for atmospheric CO2 (+0.53 mol C m-2 y-1). Overall biological activity had a stronger influence on the modelled seasonal cycle of pCO2 than temperature. Especially Phaeocystis colonies which growth in spring were associated with an important sink of atmospheric CO2 that counteracted the temperature-driven increase of pCO2 at this period of the year. However, river inputs of organic and inorganic carbon were shown to increase the surface water pCO2 and hence the emission of CO2 to the atmosphere. Same calculations conducted in WCH, showed that temperature was the main factor controlling the seasonal pCO2 cycle in these open ocean waters. The effect of interannual variations of fresh water discharge (and related nutrient and carbon inputs), temperature and wind speed was further explored by running scenarios with forcing typical of two contrasted years (1996 and 1999). Based on these simulations, the model predicts significant variations in the intensity and direction of the annual air-sea CO2 flux.

scholarly journals Metal speciation from stream to open ocean: modelling v. measurement

2016 ◽  
Vol 13 (3) ◽  
pp. 464 ◽  
Author(s):  
Edward Tipping ◽  
Stephen Lofts ◽  
Anthony Stockdale
Keyword(s):  
Coastal Waters ◽  
Natural Waters ◽  
Chemical Speciation ◽  
Metal Speciation ◽  
Open Ocean ◽  
Large Set ◽  
Data Set ◽  
Fresh Waters ◽  
Speciation Model ◽  
Model Predictions

Environmental contextThe chemical speciation of metals strongly influences their transport, fate and bioavailability in natural waters. Analytical measurement and modelling both play important roles in understanding speciation, while modelling is also needed for prediction. Here, we analyse a large set of data for fresh waters, estuarine and coastal waters, and open ocean water, to examine how well measurements and modelling predictions agree. AbstractWe compiled a data set of ~2000 published metal speciation measurements made on samples of fresh waters, estuarine and coastal waters, and open ocean waters. For each sample, we applied the chemical speciation model WHAM7 to calculate the equilibrium free metal ion concentrations, [M] (molL–1), amounts of metal bound by dissolved organic matter (DOM), ν (molg–1), and their ratio ν/[M] (L g–1), which is a kind of ‘local’ partition coefficient. Comparison of the measured and predicted speciation variables for the whole data set showed that agreements are best for fresh waters, followed by estuarine and coastal waters, then open-ocean waters. Predicted values of ν/[M], averaged over all results for each metal, closely follow the trend in average measured values, confirming that metal reactivity, and consequent complexation by DOM, in natural waters accord with the expectations of the speciation model. Comparison of model predictions with measurements by different analytical techniques suggests that competitive ligand–stripping voltammetry methods overestimate metal complexation by DOM, and therefore underestimate [M]. When measurements by other methods are compared with predictions, for all metals, reasonable agreement with little bias is obtained at values of ν>10–6molg–1 DOM, but at lower values of ν, the model predictions of [M] are mostly higher than the measured values, and the predictions of ν and ν/[M] are mostly lower. Research is needed to establish whether this reflects analytical error or the failure of the model to represent natural high-affinity ligands.

Biological production of methyl bromide in the coastal waters of the North Sea and open ocean of the northeast Atlantic

1999 ◽  
Vol 64 (4) ◽  
pp. 267-285 ◽  
Author(s):  
J.M Baker ◽  
C.E Reeves ◽  
P.D Nightingale ◽  
S.A Penkett ◽  
S.W Gibb ◽  
...  
Keyword(s):  
North Sea ◽  
Methyl Bromide ◽  
Coastal Waters ◽  
Open Ocean ◽  
Biological Production ◽  
Northeast Atlantic ◽  
The North ◽  
The North Sea

Fatty Acids Derived from Lipids of Marine Origin

1965 ◽  
Vol 22 (5) ◽  
pp. 1107-1122 ◽  
Author(s):  
P. M. Williams
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Coastal Waters ◽  
Acid Content ◽  
Surface Sediments ◽  
Sea Water ◽  
Fatty Acid Content ◽  
Dry Weight ◽  
Open Ocean ◽  
Marine Origin

Fatty Acids in sea water were found in concentrations of 1–9 μg/litre and 1–30 μg/litre for the dissolved and particulate fractions, respectively. Little variations were observed with depth or along a profile from coastal waters out into the open ocean. The total dissolved fatty acid concentrations were 10 to 100 times lower than had been previously reported. The fatty acid content of surface sediments varied from 13 to 67 μg/g dry weight of sediment.Six species of marine phytoplanktonic algae, two zooplankton samples, and liver extracts from hake and whiting were analyzed for their fatty acid content. The algae showed individual patterns in the spectrum of fatty acids present. The zooplankton samples were similar to the hake and whiting liver extracts with respect to the ratios of palmitic to palmitoleic and stearic to oleic acids.

scholarly journals Temperate southern Australian coastal waters are characterised by surprisingly high rates of nitrogen fixation and diversity of diazotrophs

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10809
Author(s):  
Lauren F. Messer ◽  
Mark V. Brown ◽  
Paul D. Van Ruth ◽  
Mark Doubell ◽  
Justin R. Seymour
Keyword(s):  
Continental Shelf ◽  
Coastal Waters ◽  
Heterotrophic Bacteria ◽  
Pseudomonas Stutzeri ◽  
Amplicon Sequencing ◽  
Open Ocean ◽  
Sulfate Reducing ◽  
Isotope Tracer ◽  
Low Concentrations ◽  
Inverse Estuary

Biological dinitrogen (N2) fixation is one mechanism by which specific microorganisms (diazotrophs) can ameliorate nitrogen (N) limitation. Historically, rates of N2 fixation were believed to be limited outside of the low nutrient tropical and subtropical open ocean; however, emerging evidence suggests that N2 fixation is also a significant process within temperate coastal waters. Using a combination of amplicon sequencing, targeting the nitrogenase reductase gene (nifH), quantitative nifH PCR, and 15N2 stable isotope tracer experiments, we investigated spatial patterns of diazotroph assemblage structure and N2 fixation rates within the temperate coastal waters of southern Australia during Austral autumn and summer. Relative to previous studies in open ocean environments, including tropical northern Australia, and tropical and temperate estuaries, our results indicate that high rates of N2 fixation (10–64 nmol L−1 d−1) can occur within the large inverse estuary Spencer Gulf, while comparatively low rates of N2 fixation (2 nmol L−1 d−1) were observed in the adjacent continental shelf waters. Across the dataset, low concentrations of NO3/NO2 were significantly correlated with the highest N2 fixation rates, suggesting that N2 fixation could be an important source of new N in the region as dissolved inorganic N concentrations are typically limiting. Overall, the underlying diazotrophic community was dominated by nifH sequences from Cluster 1 unicellular cyanobacteria of the UCYN-A clade, as well as non-cyanobacterial diazotrophs related to Pseudomonas stutzeri, and Cluster 3 sulfate-reducing deltaproteobacteria. Diazotroph community composition was significantly influenced by salinity and SiO4 concentrations, reflecting the transition from UCYN-A-dominated assemblages in the continental shelf waters, to Cluster 3-dominated assemblages in the hypersaline waters of the inverse estuary. Diverse, transitional diazotrophic communities, comprised of a mixture of UCYN-A and putative heterotrophic bacteria, were observed at the mouth and southern edge of Spencer Gulf, where the highest N2 fixation rates were observed. In contrast to observations in other environments, no seasonal patterns in N2 fixation rates and diazotroph community structure were apparent. Collectively, our findings are consistent with the emerging view that N2 fixation within temperate coastal waters is a previously overlooked dynamic and potentially important component of the marine N cycle.

scholarly journals Evolution of Ocean Color Atmospheric Correction: 1970–2005

2021 ◽  
Vol 13 (24) ◽  
pp. 5051
Author(s):  
Howard R. Gordon
Keyword(s):  
Coastal Waters ◽  
Spectral Region ◽  
Ocean Color ◽  
Atmospheric Correction ◽  
Visible Region ◽  
Coastal Areas ◽  
Open Ocean ◽  
Water Properties ◽  
Blue Spectral Region ◽  
Global Data

Retrieval of water properties from satellite-borne imagers viewing oceans and coastal areas in the visible region of the spectrum requires removing the effect of the atmosphere, which contributes approximately 80–90% of the measured radiance over the open ocean in the blue spectral region. The Gordon and Wang algorithm originally developed for SeaWiFS (and used with other NASA sensors, e.g., MODIS) forms the basis for many atmospheric removal (correction) procedures. It was developed for application to imagery obtained over the open ocean (Case 1 waters), where the aerosol is usually non-absorbing, and is used operationally to process global data from SeaWiFS, MODIS and VIIRS. Here, I trace the evolution of this algorithm from early NASA aircraft experiments through the CZCS, OCTS, SeaWiFs, MERIS, and finally the MODIS sensors. Strategies to extend the algorithm to situations where the aerosol is strongly absorbing are examined. Its application to sensors with additional and unique capabilities is sketched. Problems associated with atmospheric correction in coastal waters are described.

Development of automated surface seawater nitrate mapping systems for use in open ocean and coastal waters

1996 ◽  
Vol 43 (11-12) ◽  
pp. 1763-1775 ◽  
Author(s):  
Carole M. Sakamoto ◽  
Gernot E. Friederich ◽  
Susan K. Service ◽  
Francisco P. Chavez
Keyword(s):  
Coastal Waters ◽  
Open Ocean ◽  
Surface Seawater ◽  
Mapping Systems

scholarly journals Climate and air quality trade-offs in altering ship fuel sulfur content

2013 ◽  
Vol 13 (23) ◽  
pp. 12059-12071 ◽  
Author(s):  
A. I. Partanen ◽  
A. Laakso ◽  
A. Schmidt ◽  
H. Kokkola ◽  
T. Kuokkanen ◽  
...  
Keyword(s):  
Air Quality ◽  
Health Effects ◽  
Sulfur Content ◽  
Coastal Waters ◽  
Radiative Forcing ◽  
Premature Mortality ◽  
Open Ocean ◽  
Cooling Effect ◽  
Trade Offs ◽  
Emission Controls

Abstract. Aerosol particles from shipping emissions both cool the climate and cause adverse health effects. The cooling effect is, however, declining because of shipping emission controls aiming to improve air quality. We used an aerosol-climate model ECHAM-HAMMOZ to test whether by altering ship fuel sulfur content, the present-day aerosol-induced cooling effect from shipping could be preserved, while at the same time reducing premature mortality rates related to shipping emissions. We compared the climate and health effects of a present-day shipping emission scenario (ship fuel sulfur content of 2.7%) with (1) a simulation with strict emission controls in the coastal waters (ship fuel sulfur content of 0.1%) and twofold the present-day fuel sulfur content (i.e. 5.4%) elsewhere; and (2) a scenario with global strict shipping emission controls (ship fuel sulfur content of 0.1% in coastal waters and 0.5% elsewhere) roughly corresponding to international agreements to be enforced by the year 2020. Scenario 1 had a slightly stronger aerosol-induced effective radiative forcing (ERF) from shipping than the present-day scenario (−0.43 W m−2 vs. −0.39 W m−2) while reducing premature mortality from shipping by 69% (globally 34 900 deaths avoided per year). Scenario 2 decreased the ERF to −0.06 W m−2 and annual deaths by 96% (globally 48 200 deaths avoided per year) compared to present-day. Our results show that the cooling effect of present-day emissions could be retained with simultaneous notable improvements in air quality, even though the shipping emissions from the open ocean clearly have a significant effect on continental air quality. However, increasing ship fuel sulfur content in the open ocean would violate existing international treaties, could cause detrimental side-effects, and could be classified as geoengineering.

The structure of the transition zone between coastal waters and the open ocean off northern California, winter and spring 1987

1991 ◽  
Vol 96 (C8) ◽  
pp. 14707 ◽  
Author(s):  
P. Michael Kosro ◽  
Adriana Huyer ◽  
Steven R. Ramp ◽  
Robert L. Smith ◽  
Francisco P. Chavez ◽  
...  
Keyword(s):  
Transition Zone ◽  
Coastal Waters ◽  
Open Ocean ◽  
Northern California
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