Search results

Title: Does inorganic carbon assimilation cause 14C depletion in deep-sea organisms?,
Description: The metabolic activities within and feeding relationships among deep-sea biota require that significant quantities of 14C-depleted carbon be incorporated into their biomass. These processes cannot be ignored when interpreting the 14C abundances of organisms and organic materials in the deep ocean. © 1986., Cited By (since 1996):10, Oceanography, ,
Author: Rau, Karl, Carney
Date: 1986-01-01T00:00:00Z

Title: The carbon balance during the 1989 spring bloom in the North Atlantic Ocean, 47°N, 20°W,
Description: We report on studies of the carbon balance of the upper water column, done as part of the JGOFS North Atlantic Bloom Experiment, over a 13-day period, at 47°N, 20°W, during the 1989 spring phytoplankton bloom. Gross carbon production was calculated from data on 18O gross O 2 production and from 14C production as well. Net carbon production was calculated from net O 2 production rates measured in vitro, as well as from changes in the inventories of nutrients and O 2 along with O 2 evasion rates by gas exchange. Gross carbon production during this period was measured to be 1.83 mol m -2, and net production was 0.68 mol m -2. Of this net carbon production, 0.30 mol m -2 was stored in the euphotic zone as particulate organic carbon, and 0.09 mol m -2 rained out to depths >150 m. The remainder was remineralized to DIC in the 50-150 m depth interval, with perhaps some DOC storage in the upper 150 m. © 1992., Cited By (since 1996):55, Oceanography, ,
Author: Bender, Ducklow, Kiddon, Marra, Martin
Date: 1992-01-01T00:00:00Z

Title: VERTEX: carbon cycling in the northeast Pacific,
Description: Particulate organic carbon fluxes were measured with free-floating particle traps at nine locations during VERTEX and related studies. Examination of these data indicated that there was relatively little spatial variability in open ocean fluxes. To obtain mean rates representative of the oligotrophic environment, flux data from six stations were combined and fitted to a normalized power function, F = F 100 (z/100) b; e.g. the open ocean composite C flux in mol m -2 y -1 = 1.53 (z/100 -0.858 with depth z in meters. It is shown that the vertical derivative of particulate fluxes may indicate solute regeneration rates, and accordingly regeneration rates for C, H and N were estimated. Oxygen utilization rates were also estimated under the assumption that 1.5, 1.0 and 0.25 moles of O 2 were used for each mole of N, C and H regenerated. Regeneration ratios of these elements were depth-dependent: i.e. N:C:H:-O 2 = 1.0 N: 6.2 (z/100) 0.130 C: 10.0(z/100) 0.146 H: [1.5 + 6.2 (z/100) 0.130 + 2.5 (z/100) 0.146]-O 2. Comparisons of our rates with those in the literature indicate that trap-derived new productivities in the open Pacific (≈1.5 mol C m -2 y -1) are substantially less than those estimated from oxygen utilization rates in the Sargasso Sea (≈4 mol C m -2 y -1). A hypothesis is presented which attempts to explain this discrepancy on the basis of the lateral transport and decomposition of slow or non-sinking POC in the Sargasso Sea. Data gathered during the VERTEX studies are also used for various global estimates. Open ocean primary productivities are estimated at 130 g C m -2 y -1 which results in a global open ocean productivity of 42 Gt y -1. Organic C removal from the surface of the ocean via particulate sinking (new production) is on the order of 6 Gt y -1. Fifty percent of this C is regenerated in the upper 300 m of the water column. The ratio of new production (measured with traps) to total primary production (measured via 14C) is 0.14. It is concluded that the 14C technique yields reasonable estimates of primary productivity provided that care is taken to prevent heavy metal contamination. © 1987., Cited By (since 1996):671, Oceanography, ,
Author: Martin, Knauer, Karl, Broenkow
Date: 1987-01-01T00:00:00Z

Title: Silver distributions and fluxes in north-east Pacific waters,
Description: In recent years, significant knowledge has been gained about the oceanic distributions of several trace elements 1,2. However, relatively little is known about amounts of Ag in the ocean, and how this element cycles through it. We report here that Ag levels are relatively low near the surface (∼1 pmol kg -1), and that concentrations more or less steadily increase with depth; for example, 23 pmol kg -1 at 2,440 m, the deepest sample we collected. In general, Ag depth profiles are similar to those observed for Cu (Fig. 1). The near-surface cycles of Ag appears to be involved with particulate organic matter uptake-sinking-regeneration processes. © 1983 Nature Publishing Group., Cited By (since 1996):39, Oceanography, ,
Author: Martin, Knauer, Gordon
Date: 1983-01-01T00:00:00Z

Title: VERTEX lateral transport: The lateral transport of manganese in the northeast Pacific,
Description: Vertical distributions (0 to 2000 m) of dissolved Mn were measured at 5 stations on a 3200-km east-west (California to Hawaii) transect during the VERTEX (Vertical Transport and Exchange) IV and V cruises. All profiles shared common features: surface maxima, subsurface minima, maxima associated with the oxygen minimum, and relatively low levels at depth. Particulate Mn fluxes, measured at four of the five stations using free-floating particle traps (∼ 100 to 2000 m), indicated that in situ particulate scavenging was not responsible for the formation of the subsurface dissolved Mn minimum nor was in situ particulate Mn regeneration responsible for the dissolved Mn maximum associated with the oxygen minimum. Thus, these dissolved Mn extrema result primarily from lateral advective transport processes. The Mn minimum is associated with the shallow salinity minimum, a water mass that sinks away from the surface in the North Pacific (∼ 47°N), and spreads to the south and east in our study area. Additional evidence of the onshore flow of open-ocean, near-surface water is provided by the high Pb concentrations (∼ 50 pmol kg -1 associated with this feature. Waters in the oxygen minimum/ Mn maximum appear to have northerly and offshore flow in our study area. Box model estimates indicate that offshore lateral advective velocities must approach 0.4 cm s -1 to balance vertical diffusive losses from the oxygen minimum/dissolved Mn maximum. Maintenance of the subsurface Mn minimum requires onshore lateral transport of water with low Mn content at velocities on the order of 0.9 cm s -1 offshore, increasing to 4.4 cm s -1 inshore. These velocities represent maximum estimates since north-south Mn distribution data were not available. © 1985., Cited By (since 1996):23, Oceanography, ,
Author: Martin, Knauer, Broenkow
Date: 1985-01-01T00:00:00Z

Title: Spatial and temporal variability in copper complexation in the North Pacific,
Description: The complexation of trace metals by organic ligands has long been proposed to play a significant role in determining trace metal speciation in seawater. However, analytical methodologies with sufficient specificity and sensitivity only recently have been developed to enable us to address questions of trace metal/organic complexation. In this study copper titrations were conducted at sea using differential pulse anodic stripping voltammetry on North Pacific samples to determine the extent of copper complexation with organic ligands. This study includes data from a transect from 33°N, 139°W to 55°N, 148°W and seasonal occupations of the VERTEX T-4 station (33°N, 139°W). The data indicate the presence of at least two copper binding ligands: L1, the stronger ligand, or ligand class, averages 2 nM with log K′l cond(Cu′) = 11.6; L2, the weaker ligand class varies between 5 and 10 nM witgh log K′2 cond(Cu′) = 8.6. The presence of these ligands strongly buffers the activity of copper(II) in surface waters at all stations. Seasonal variations in the distribution of strong copper complexing ligands follow seasonal variations in the depth of the mixed layer at T-4 and indicate a ligand source in the lower mixed layer. Ligand concentrations do not covary with the rates of primary productivity in a latitudinal transect from the central North Pacific to the subarctic. Ligand concentrations at all stations vary only by a factor of two and hold surface water copper(II) ion activities relatively constant (about 10-14 M), suggestive of a regulated ligand production mechanism. These results comprise a unique data set for copper complexation in the Pacific and may have significantly implications for the distribution of plankton between oligotrophic and subarctic systems. © 1990., Cited By (since 1996):113, Oceanography, ,
Author: Coale, Bruland
Date: 1990-01-01T00:00:00Z

Title: The 154-year record of sea level at San Francisco: Extracting the long-term trend, recent changes, and other tidbits,
Description: A data adaptive method called ensemble empirical mode decomposition (EEMD) is used to examine the 154-year record of monthly sea level at San Francisco. The mode that is lowest in frequency corresponds to the long-term trend. The next highest mode corresponds to an oscillation with a period of ~100 years and may be related to solar variability. When this mode is combined with the long-term trend, the rate of increase in sea level starts to decrease by ~1980. The next lower mode corresponds to interdecadal time scales and thus includes the Pacific Decadal Oscillation. When combined with the two lower modes, sea level itself starts to decrease by the mid-1990s. These results are consistent with the most recent results from the intergovernmental panel on climate change (IPCC), and may be the first obtained from a tidal record. Prior to conducting EEMD, corrections for glacial isostatic adjustment (GIA) and the inverse barometer (IB) effect were applied. The effect of applying the GIA correction was relatively small, but the IB correction reduced the slope of the long-term trend in sea level by almost 15%. This reduction is due to a long-term increase in the variance of sea level pressure. To determine if the 10-15 year ENSO modulation cycle could be detected from the decomposition we first compared the envelope from the mode associated with ENSO, with the two adjacent modes that were lower in frequency. Spectral analysis revealed no significant maxima in the ENSO mode envelope, but a major peak in the spectrum for the two adjacent modes, with a period of 12. 8 years. This is consistent with a local response to El Niño warming for the ENSO mode, but a non-local response for the two adjacent modes. A similar analysis was performed for the Southern Oscillation Index and a spectral maximum was found between 12 and 16 years, consistent with our non-local interpretation of the previous two modes. © 2010 Springer-Verlag., Cited By (since 1996):5, Oceanography, ,
Author: Breaker, Ruzmaikin
Date: 2011-01-01T00:00:00Z

Title: Development of a real-time regional ocean forecast system with application to a domain off the U.S east coast,
Description: This paper discusses the needs to establish a capability to provide real-time regional ocean forecasts and the feasibility of producing them on an operational basis. Specifically, the development of a Regional Ocean Forecast System using the Princeton Ocean Model (POM) as a prototype and its application to the East Coast of the U.S. are presented. The ocean forecasts are produced using surface forcing from the Eta model, the operational mesoscale weather prediction model at the National Centers for Environmental Prediction (NCEP). At present, the ocean forecast model, called the East Coast-Regional Ocean Forecast System (EC-ROFS) includes assimilation of sea surface temperatures from in situ and satellite data and sea surface height anomalies from satellite altimeters. Examples of forecast products, their, evaluation, problems that arose during the development of the system, and solutions to some of those problems are also discussed. Even though work is still in progress to improve the performance of EC-ROFS, it became clear that the forecast products which are generated can be used by marine forecasters if allowances for known model deficiencies are taken into account. The EC-ROFS became fully operational at NCEP in March 2002, and is the first forecast system of its type to become operational in the civil sector of the United States., Cited By (since 1996):2, Oceanography, ,
Author: Breaker, Rao, Kelley, Balasubramaniyan
Date: 2004-01-01T00:00:00Z

Title: VERTEX manganese transport with CaCO3,
Description: Manganese transport was studied off central California in August and September 1981 as part of the VERTEX (Vertica l Transport and Exchange) research program. Refractory, leachable, and dissolved Mn fractions associated with particles caught in traps set at 11 depths (50 to 2000 m) were analyzed. Through intentional and unintentional CaCO3 dissolution 'experiments', it was learned that the weakly leachable Mn was originally in association with the carbonate phase. Adsorption on surfaces rather than absorption in CaCO3 matrices was indicated by the finding that Mn was not released in proportion to the CaCo3 dissolved, instead it appeared to keep readsorbing to the dissolving surface. Ultimately, Mn went into solution when the particulate CaCO3 was essentially depleted, suggesting that sufficient sites for adsorption were no longer available. Manganese fluxes with CaCO3 were low near the surface (0.1 mg cm-2 ky-1), but increased rapidly in the 50 to 200-m depth interval, and then became more or less constant (1.3 mg cm-2 ky-1 for the remainder of the water column (300 to 2000 m). Rate-of-change estimates indicate that Mn is rapidly scavenged in near-surface waters (-130 ng 1-1 y-1) and slowly regenerated at depth (2.7 ng 1-1 y-1) in our near-shore study area. Residence times for dissolved Mn were estimated at 1.2 y for surface waters and 17 y at depth. The implications of Mn transport with CaCO3 in relation to open-ocean sediment excess Mn are discussed. © 1983., Cited By (since 1996):15, Oceanography, ,
Author: Martin, Knauer
Date: 1983-01-01T00:00:00Z

Title: Manganese cycling in northeast Pacific waters,
Description: Particles trapped at depths of 35, 65, 150, 500, 750 and 1500 m in nearshore Californica waters were analyzed for their associated Mn, Al and C content. Although the concentrations of A1 and Mn indicated that the trapped particulates were primarily alumino-silicates, an additional fraction of originally weakly sorbed Mn (5-30%) was found dissolved in the sediment trap salt solutions. The latter Mn was significantly correlated with the trapped particulate organic C and suggests that passively sinking organic detritus is responsible for the removal of dissolved Mn from the water column. The fluxes resulting from this process are on the order of 35 μg Mn/cm 2 kyr in the mid-water column and thus represent an improtant factor in marine Mn balance schemes. Amounts of dissolved Mn in the surface waters of the study area always exceeded those in the mid-water column in spite of surface Mn removal at a rate of 1200 μg/cm 2 kyr. The only Mn source large enough to balance this removal would appear to be continental weathering, either dissolved riverine Mn or Mn released via the weathering of particulate riverine Mn after its introductive into the marine environment. Residence times based on actual flux and water column measurements were 1.8 years for surface waters and 31 years for the upper 1500 m of the water column. © 1980 Elsevier Scientific Publishing Company., Cited By (since 1996):9, Oceanography, ,
Author: Martin, Knauer
Date: 1980-01-01T00:00:00Z

Title: Bioluminescence profile in the deep Pacific Ocean,
Description: The vertical profile of bioluminescence at a station hear Hawaii has been measured to a depth of 4300 m using a calibrated instrument with a threshold sensitivity of 400 photons cm-2 s-1. The measured light is dominated by flashes over a very faint ambient background. The median light levels follow an exponential scaling law below 2000 m and decrease at the rate of 1/e per kilometer. Stimulated bioluminescence is observed in the wake of the instrument, even at depth. © 1987., Cited By (since 1996):14, Oceanography, ,
Author: Bradner, Bartlett, Blackinton, Clem, Karl, Learned, Lewitus, Matsuno, O'Connor, Peatman, Reichle, Roos, Waters, Webster, Yarbrough
Date: 1987-01-01T00:00:00Z

Title: Alliance for coastal technologies: Advancing moored pCO2 instruments in coastal waters
Description: The Alliance for Coastal Technologies (ACT) has been established to support innovation and to provide the information required to select the most appropriate tools for studying and monitoring coastal and ocean environments. ACT is a consortium of nationally prominent ocean science and technology institutions and experts who provide credible performance data of these technologies through third-party, objective testing. ACT technology verifications include laboratory and field tests over short- and long-term deployments of commercial technologies in diverse environments to provide unequivocal, unbiased confirmation that technologies meet key performance requirements. ACT demonstrations of new technologies validate the technology concept and help eliminate performance problems before operational introduction. ACT's most recent demonstration of pCO2 sensors is an example of how ACT advances the evolution of ocean observing technologies, in this case to address the critical issue of ocean acidification, and promotes more informed decision making on technology capabilities and choices., Cited By (since 1996):1, Oceanography
Author: Tamburri, Johengen, Atkinson, Schar, Robertson, Purcell, Smith, Pinchuk, Buckley
Date: 2011-01-01T00:00:00Z

Title: Short-term temperature variability in the Rose Garden hydrothermal vent field: An unstable deep-sea environment,
Description: Temperature was measured within the animal communities of the Rose Garden hydrothermal vent field with three thermistors that were left in place for a period of 72 h. The highest mean temperature (5.54°C) was measured at a thermistor placed in the central clump of vestimentiferan worms, while the lowest mean value (2.26°C) was recorded over the basaltic substrate. The temperature of the ambient water in the field was 2.07°C. The site with the highest temperature was characterized by extreme variability in the temperature, with minimum values of 2.16°C and maximum values of 14.81°C. The temperature fluctuated over all of the time scales studied from 1 s to 72 h. There was no clear periodicity to the temperature fluctuations, however. These temperature fluctuations must have significant impacts on adaptations, by the animals of the vent community. In fact, the variability in temperature may be more important to the community than the mean temperature value to which they are exposed. © 1988., Cited By (since 1996):73, Oceanography, ,
Author: Johnson, Childress, Beehler
Date: 1988-01-01T00:00:00Z

Title: The relationship between δ13C of organic matter and [CO2(aq)] in ocean surface water: Data from a JGOFS site in the northeast Atlantic Ocean and a model,
Description: The δ13C of suspended particulate organic matter (SPOM) in surface waters increased from -22.9 to -18.1‰ during April 25-May 31, 1989 at the JGOFS North Atlantic Bloom Experiment Site (NABE Site; 47°N, 20°W). During the same period, nearly parallel increases in sinking POM δ13C were also found, although these values were usually lower than those of the corresponding SPOM. Consistent with the hypothesis that plankton δ13C and [CO2(aq)] are inversely related, the increases in both sinking and suspended POM δ13C were highly negatively correlated with mixed-layer [CO2(aq)] that generally decreased from 10.1-13.2 μmoles/kg during the five weeks. The change in SPOM δ13C per change in [CO2(aq)], however, appears to be somewhat greater than that expected from previous, though less direct, ocean and laboratory evidence. By adapting a model of plant δ13C by Farquhar et al. (1982), it is shown that under a constant phytoplankton demand for CO2 an inverse, nonlinear SPOM δ13C response to ambient [CO2(aq)] is expected. Such trends are unlike the negative linear relationships indicated by data from the NABE Site and or from Southern Hemisphere waters. Such differences between predicted and observed SPOM δ13C vs. [CO2(aq)] trends and among observed relationships can be reconciled, however, if biological CO2 demand is allowed to vary. This has significant implications for the use of the δ13C of plankton (or their organic subfractions or sedimentary remains) as a proxy for past or present ocean CO2 concentrations and biological productivity. © 1992., Cited By (since 1996):148, Oceanography, ,
Author: Rau, Takahashi, Des Marais, Repeta, Martin
Date: 1992-01-01T00:00:00Z

Title: A closer look at regime shifts based on coastal observations along the eastern boundary of the North Pacific,
Description: At least six regime shifts have been reported in the North Pacific since 1920. They occurred in 1925, 1939, 1946, 1976-1977, 1989 and 1999. The major change in 1976-1977 corresponds to a regime shift that is now widely accepted as a canonical event since it had a significant impact on virtually all climatic and ecosystem indicators. We seek to determine if daily sea surface temperature (SST) from Pacific Grove, in central California, and Scripps Pier, in southern California, and coastal observations from several other locations along the west coast of North America can be used to detect and resolve these events. Cumulative sums (CUSUMs) were initially calculated to enhance the detection process. The CUSUM trajectories during the 1976-1977 event at Pacific Grove and Scripps Pier were distinctive, highly correlated, and in phase. The turning point patterns from this event were then used to search for other events that have been reported since 1920. Turning point patterns very similar to the 1976-1977 event were detected in 1946 and 1989. The events in 1925 and 1939 were generally similar, but the CUSUM patterns for the event in 1999 departed significantly from the other events. Further examination of the 1976 and 1989 events revealed inflection points in the CUSUMs near the beginning and end of each transition that correspond to critical values or extrema in the original data. The inflection points and/or critical values provide an improved basis for determining the duration of these events. The robustness of the CUSUM approach for detecting regime shifts was examined by posing the inverse problem to determine if other possible regime changes could be detected that have not been previously reported. The period between 1946 and 1976 was examined, and one match in 1972 was found, which coincided with a large shift in the Aleutian Low Pressure Index. The CUSUM patterns associated with well-defined regime shifts may be essentially unique and thus useful in searching for other events. Whether the temperature ultimately increases or decreases following a regime shift is well-predicted by the sign of the CUSUM slope during an event. Testing regime shifts for statistical significance may be problematic, but our results suggest that when CUSUMs are employed, the detection problem becomes one that is more closely related to pattern recognition where other tests could be applied. CUSUMs often produce a distinct pattern that appears to be characteristic of regime shifts. During well-defined events such as those that occurred in 1946, 1976, and 1989, the CUSUM trajectories from Pacific Grove and Scripps Pier were highly synchronized and nearly identical in form. The CUSUM transformation allows us to identify, localize and observe how these events evolve. We have only been able to examine these events in such detail because daily observations from single locations were used. Based on the events we have examined, they have time scales that range from about 4-9 months. Salinity and sea level data were also employed in this study and were found to be less sensitive to the changes associated with regime shifts than SST. Regime shifts detected in CUSUMs of SST at two locations off Vancouver Island were found to be weaker in amplitude and less well-defined than those detected at Pacific Grove and Scripps Pier. However, they were in phase with the events observed further south. Establishing the connection between these results, and changes in the ecosystems of the North Pacific, should be given a high priority. Finally, the results of this study are related to decadal climate variability and provide additional insight into the nature of this phenomenon. © 2007 Elsevier Ltd. All rights reserved., Cited By (since 1996):8, Oceanography, ,
Author: Breaker
Date: 2007-01-01T00:00:00Z

Title: Cobalt and copper distributions in the waters of Santa Monica Basin, California,
Description: The trace metals cobalt and copper are removed from the oceans interior by scavenging on to particle surfaces, but the mechanisms for removal of these two metals are probably quite different. Cobalt appears to be scavenged by manganese oxide particles, whereas organic compounds are the main carrier phase for copper. Remobilization of these metals in marine sediments therefore proceeds by different pathways. The differences in the pathways of remobilization are accentuated in oxygen-deficient environments: manganese oxide reduction is accelerated at low oxygen levels and organic carbon is preserved. Cobalt fluxes from sediments underlying oxygen-deficient waters should be enhanced and copper fluxes reduced. We report here measurements of the cobalt and copper distributions in the waters of an oxygen-deficient marine basin in the Southern California Bight. Cobalt concentrations near the bottom are raised four times above the background level, whereas copper concentrations show no increase. These measurements confirm features of existing models for the oceanic cycles of these metals., Cited By (since 1996):18, Oceanography, CODEN: NATUA, ,
Author: Johnson, Stout, Berelson, Sakamoto-Arnold
Date: 1988-01-01T00:00:00Z

Title: Contamination of the deep-sea,
Description: Cited By (since 1996):17 Oceanography, CODEN: MPNBA, , ,
Author: Ballschmiter, Froescheis, Jarman, Caillet
Date: 1997-01-01T00:00:00Z

Title: The effects of Cu on the adenylate energy charge of open ocean phytoplankton,
Description: The effects of short-term, acute Cu exposure (6 h) on the adenylate energy charge (EC A) of open-ocean phytoplankton populations (northeastern equatorial Pacific) were investigated. Energy charge remained at ̃0.77 over the range of Cu additions (0.025 - 5.μg l -1), even though 14C uptake and total adenylate levels (ATP + ADP + AMP) were reduced by as much as 60%. These findings suggest that EC A alone is not a sensitive indicator of acute sublethal metal effects on phytoplankton. © 1983 IRL Press Ltd., Cited By (since 1996):1, Oceanography, CODEN: JPLRD, ,
Author: Fitzwater, Knauer, Martin
Date: 1983-01-01T00:00:00Z

Title: Dissolved oxygen dynamics in a eutrophic estuary, Upper Newport Bay, California,
Description: Eutrophication often causes hypoxia in estuarine and coastal systems, but the mechanisms that control hypoxic events vary among estuaries and are often difficult to discern. We monitored surface and bottom dissolved oxygen (DO) in the Upper Newport Bay (UNB), a tidally mixed estuary in southern California subject to anthropogenic nutrient loading, eutrophication and hypoxia. Our goal was to identify the environmental factors regulating DO dynamics. Six hypoxic events occurred between June and November and were associated with a combination of low solar radiation, increased freshwater discharge following precipitation, and enhanced haline stratification during reduced tidal range periods. At the head of the estuary, high macroalgal biomass and pronounced haline stratification resulted in high DO in the surface layer and low DO in the bottom layer. Oxygen-rich and oxygen-poor waters were transported down-estuary by ebb tides, resulting in DO heterogeneity throughout the UNB. Cross-wavelet analysis illustrated the down-estuary propagation of high/low DO signal correlated with the phases of diurnal photosynthetic and semi-diurnal tidal cycles. © 2009 Elsevier Ltd. All rights reserved., Cited By (since 1996):10, Oceanography, CODEN: ECSSD, ,
Author: Nezlin, Kamer, Hyde, Stein
Date: 2009-01-01T00:00:00Z

Title: Benthic manganese fluxes along the Oregon-California continental shelf and slope
Description: Here we examine the factors that influence the manganese (Mn) benthic flux from eastern North Pacific marine sediments, with a primary emphasis on continental shelf locations off Oregon and California and studies that involve the use of in situ benthic chambers. Typical shelf-to-shallow margin (<~350m) sites have benthic Mn efflux rates that average ~8±5μmolm-2d-1. In contrast, for the Eel River continental shelf region the benthic Mn efflux can be an order of magnitude higher than other shelf settings with benthic effluxes exceeding ~50μmolm-2d-1. Based on prior work and some new results, continental margin and slope sites (350-~4000m) have benthic Mn efflux rates that average ~1±1μmolm-2d-1. The combination of the benthic flux and Mn solid-phase data, indicate that for the continental shelf off the Umpqua and Eel Rivers, approximately 15±10% of the total Mn that is delivered to the seafloor is remobilized. The compiled data set shows that the benthic Mn efflux co-varies with the organic carbon oxidation rate with a Mn to organic carbon oxidation (Cox) ratio of ~0.8mmol Mn mol-1. Although this ratio can be as high as ~5 for some Eel River sites, the generally close correspondence between Mn and organic carbon implies that the organic carbon oxidation rate exerts some primary control over the rate of the Mn efflux. The amount of organic carbon oxidized by Mn-oxides, however, represents a small fraction (i.e., generally <1%) of the total organic carbon oxidized in these seafloor sediments. © 2012 Elsevier Ltd., Cited By (since 1996):5, Oceanography, CODEN: CSHRD
Author: McManus, Berelson, Severmann, Johnson, Hammond, Roy, Coale
Date: 2012-01-01T00:00:00Z

Title: The development of a new optical total suspended matter algorithm for the Chesapeake Bay,
Description: Sediment loading is one of the primary threats to the health of the Chesapeake Bay. We have developed a high resolution (250m) ocean color satellite tool to monitor sediment concentrations in the Bay. In situ optical and sediment sampling is used to develop a total suspended matter (TSM) algorithm for the Chesapeake Bay. The Coastal Optical Characterization Experiment (COCE) is part of an ongoing effort to optically characterize processes and to develop regional remote sensing ocean color algorithms in the coastal waters. The goal is to characterize sediment concentrations and to develop a tool to track plumes cascading down the Bay following heavy rainfall events. Background TSM concentrations in the Chesapeake Bay Watershed can also be characterized. The plumes can have potentially devastating effects on the Chesapeake Bay's fragile ecosystem by increasing nutrient loads, depositing sediments, and decreasing salinity and light levels. Sampling took place throughout 2006 to 2008 in the upper and mid portions of the Chesapeake Bay. Measurements of TSM, chlorophyll a (Chl), and hyperspectral optics were collected. The optical measurements included above water surface irradiance (E s(λ)), in-water downwelling irradiance (E d(λ)) and in-water upwelling radiance (L u(λ)). These optical data were used to analyze the performance and utility of the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Band 1 (645nm) for use as a TSM monitoring tool. From the optical measurements we have derived a 3rd order polynomial regression of TSM to normalized water-leaving radiance (r 2=0.79) to form an algorithm that quantitatively relates TSM to the MODIS 250m resolution band 1 (645nm). The algorithm performance was validated (a mean percent difference of -4.2%) against 270 total suspended solids samples collected by the Chesapeake Bay Program during routine water quality monitoring of the Chesapeake Bay environment. The TSM algorithm tool is then used to demonstrate monitoring of significant runoff events that occurred in June, 2006 and March, 2008. In addition, the utility of the Chesapeake Bay TSM product is demonstrated by describing regional and seasonal variations in sediment concentrations throughout the Chesapeake Bay for 2009. Mean concentrations ranged from 11.55mg/l in the upper Chesapeake Bay winter season to 6.37mg/l in the middle Chesapeake Bay spring season. These remote sensing tools can be valuable instruments in the detection and tracking of runoff events and background concentration for monitoring the health and recovery of the Chesapeake Bay. © 2012., Cited By (since 1996):7, CODEN: RSEEA, , , Oceanography
Author: Ondrusek, Stengel, Kinkade, Vogel, Keegstra, Hunter, Kim
Date: 2012-01-01T00:00:00Z

Title: Spectrophotometric determination of dissolved manganese in natural waters with 1-(2-pyridylazo)-2-naphthol: Application to analysis in situ in hydrothermal plumes,
Description: A spectrophotometric method using the complexing reagent 1-(2-pyridylazo)-2-naphthol (PAN) was developed for the determination of dissolved manganese in seawater. A detection limit of approximately 22 nM was obtained when the analyses were performed in situ with a submersible chemical analyzer (Scanner). Color formation was rapid (less than 1 s), which permitted the technique to be used in flow injection and continuous flow systems. An investigation of possible interferences revealed that the only significant interferent to manganese determinations in seawater (hydrothermal plumes) was iron. The iron-specific chelating agent desferrioxamine B was used to mask this interference. Temperature and pressure did not adversely affect the sensitivity of the technique, which made it amenable to applications in situ to depths of 3000 m. This method was tested by measuring dissolved manganese concentrations in situ in submarine hydrothermal plumes using a Scanner. Scanner deployments over the Juan de Fuca Ridge produced the first near real time analyses of manganese from a hydrothermal plume environment. Estuarine samples have also been successfully analyzed in the laboratory and the results confirmed by an independent method. © 1992., Cited By (since 1996):22, Oceanography, CODEN: MRCHB, ,
Author: Chin, Johnson, Coale
Date: 1992-01-01T00:00:00Z

Title: Biomass and production of heterotrophic bacterioplankton in the oceanic subarctic Pacific,
Description: As part of the Subarctic Pacific Ecosystem Research (SUPER) program, we measured the abundance and biomass production of heterotrophic bacterioplankton in the subarctic Pacific and compared these parameters with those of phytoplankton during four cruises in 1987 and 1988. Bacterial biomass was about equal to phytoplankton biomass during all cruises. Based on rates of bacterial biomass production and assuming a growth efficiency of 50%, we estimate that heterotrophic bacteria consumed 10% (June 1987) to 24% (August 1988) of primary production in the euphotic zone. These percentages are low compared with other aquatic ecosystems, apparently due to low bacterial growth rates (<0.1 day-1) iin the subarctic Pacific. In contrast, phytoplankton growth rates were much higher (0.1-8.8 day-1). Bacterial growth rates were limited by the supply of dissolved organic matter and temperature. Even with these low growth rates, however, bacterial biomass and rates of biomass production increased by 2-5-fold in May and August 1988, changes that were not obviously related to corresponding changes in phytoplankton biomass nor primary production. Heterotrophic bacterioplankton constitutes a large reservoir of carbon and nitrogen that needs to be considered in modelling ecosystem dynamics of the subarctic Pacific. © 1993., Cited By (since 1996):101, Oceanography, CODEN: DRORE, ,
Author: Kirchman, Keel, Simon, Welschmeyer
Date: 1993-01-01T00:00:00Z

Title: The behaviour of iron and other trace elements during the IronEx-I and PlumEx experiments in the Equatorial Pacific,
Description: Dissolved (< 0.4 μm) and particulate (0.4-5 μm and > 5 μm, leachable and refractory) trace elements were measured during the IronEx I and PlumEx experiments in October and November 1993 near the Galapagos Islands. Iron was measured in the enriched patch and at control stations over a 9 day period following fertilization. The dissolved iron was initially depleted at a rate that gave an iron half-life of 28-40 h. The loss rate gradually decreased, and dissolved iron concentrations did not decrease below about 0.25 nmol kg-1 throughout the experiment. These results were most consistent with a kinetic model that was second order in iron concentration for the scavenging removal of each iron fraction. Other trace elements measured did not change significantly either in concentration or partitioning during the IronEx I experiment. Biological production tracked iron concentrations over time, which suggests that productivity within the fertilized patch was regulated by the availability of iron. The PlumEx study consisted primarily of two transects, a meridional course to the east of the Galapagos Islands and a zonal section to the west. Surface dissolved iron was very low at all stations except those near the Galapagos Islands. Sections of trace metal and other properties distinctly confirm the upwelling of the Equatorial Undercurrent as it intersects the islands. This upwelling has a great effect on the surface distributions of the trace metals on the west side of the islands. Productivity within the mixed layer of this region is highly correlated with iron and nitrate. West of the islands highest productivity is found at stations with the highest iron. North of the Equatorial front, in nitrate-depleted waters, elevated iron concentrations do not enhance productivity., Cited By (since 1996):58, Oceanography, CODEN: DSROE, ,
Author: Gordon, Johnson, Coale
Date: 1998-01-01T00:00:00Z

Title: The flux of iron from continental shelf sediments,
Description: The flux of dissolved iron from sediments to the water column was measured with flux chambers along the California coast over a five-year period. High fluxes were observed from sediments on the continental shelf. The measured fluxes were an average of 75 times larger than flux values derived from pore-water iron gradients. The iron flux was significantly correlated with the oxidation of organic matter, which allows an extrapolation to the global shelf. The input from shelf sediments is at least as significant as the global input of dissolved iron from aerosols, which has been presumed to be the dominant external iron source. Evidence of this input is seen 100's of kilometers offshore where it can enable the high productivity of broad coastal regions seen in satellite images. Copyright 2004 by the American Geophysical Union., Cited By (since 1996):125, Oceanography, CODEN: GPRLA, ,
Author: Elrod, Berelson, Coale, Johnson
Date: 2004-01-01T00:00:00Z

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