13 research outputs found
An Easy-to-Construct Automated Winkler Titration System
The instrument described in this report is an updated version of the high precision, automated Winkler titration system described by Friederich et al.(1984). The original instrument was based on the work of Bryan et al. (1976) who developed a colorimetric endpoint
detector and on the work of Williams and Jenkinson (1982) who produced an automated system that used this detector.
The goals of our updated version of the device described by Friederich et al. (1984) were as follows:
1) Move control of the system to the MS-DOS environment because HP-85 computers are no longer in production and because more user-friendly programs could be written using the IBM XT or AT computers that control the new device.
2) Use more "off the shelf" components and reduce the parts count in the new system so that it could be easily constructed and maintained.
This report describes how to construct and use the new automated Winkler titration device. It also includes information on the chemistry of the Winkler titration, and detailed instructions on how to prepare reagents, collect samples, standardize and perform the titrations (Appendix I: Codispoti, L.A. 1991 On the determination of dissolved oxygen in sea water, 15pp.). A disk containing the program needed to operate the new device is also included. (pdf contains 33 pages
Spatial and temporal variability of cadmium in Gulf Stream warm-core rings and associated waters
Seawater samples were collected and analyzed for cadmium during four cruises studying Gulf Stream warm-core rings and associated waters. Warm-core ring (WCR) 82-B was sampled in April (approximately two months after formation), in June (after seasonal stratification), and in August (during its interaction with the Gulf Stream). The SeptemberâOctober cruise studied closure and separation of a meander that formed ring 82-H. The depth of the cadmium maximum varied with the depth of the main thermocline; the maximum occurred at a potential temperature of 7.8 ± 0.5°C and sigma-theta 27.4 ± 0.05 in the Slope Water, Gulf Stream, and Sargasso Sea stations. As the upper 100 m of the ring progressed from vertically well-mixed in April to seasonally stratified in June, the mole-ratios of cadmium/nutrient removal in the mixed layer were similar to the calculated slopes of the linear regressions of cadmium with phosphate, nitrate and silicate calculated from spatial distributions. Lateral mixing processes near the boundaries of WCR 82-B markedly influenced the vertical cadmium distribution via intrusions of Shelf/Slope water containing elevated levels of cadmium. Comparison of ASV-labile and total dissolvable cadmium from the August WCR 82-B station indicated essentially 100% ASV-labile cadmium in the waters within and below the main thermocline but non-detectable (\u3c0.010 nmol kgâ1) ASV-labile cadmium in the waters above the thermocline
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Influence of Rossby waves on nutrient dynamics and the plankton community structure in the North Pacific subtropical gyre
Nitrate concentrations, chlorophyll a (Chl a) fluorescence, radiance, salinity, and
temperature were measured on the Hawaii Air-Sea Logging Experiment, A Long-Term
Oligotrophic Habitat Assessment (HALE ALOHA) mooring located near the Hawaii
Ocean Time-Series (HOT) Programâs Station ALOHA (22°45âN; 158°W). Nitrate
concentrations were determined with OsmoAnalyzers deployed at depths of 120 and
180 m. Deployments in 1997 and 1999 captured monthlong events that brought relatively
cold high-nitrate seawater up into the euphotic zone. These events were correlated with
negative sea surface height (SSH) anomalies measured by the TOPEX/Poseidon satellite
altimeter. These nutrient injections at the Hawaii site were predominantly associated
with first baroclinic mode Rossby waves. Elevated nitrate concentrations resulted in
increased Chl a concentrations, increased primary productivity, and shifts in the
phytoplankton community structure, as determined by HPLC analysis of pigment
concentrations. The relative increase in pigments associated with phytoplankton that can
grow rapidly and exploit nitrate (e.g., haptophytes and pelagophytes) coincided with the
passage of Rossby waves in 1997â1999. A long-term combination of satellite remote
sensing, moored instrumentation or remote vehicles and periodic ship-based sampling is
needed to fully characterize the spatial and temporal variability due to the passage of
Rossby waves and their associated biological responses.Keywords: nitrate, nutrient, Rossby waves, phytoplankton, mooringKeywords: nitrate, nutrient, Rossby waves, phytoplankton, moorin
Characterizing Emerging Canine H3 Influenza Viruses.
The continual emergence of novel influenza A strains from non-human hosts requires constant vigilance and the need for ongoing research to identify strains that may pose a human public health risk. Since 1999, canine H3 influenza A viruses (CIVs) have caused many thousands or millions of respiratory infections in dogs in the United States. While no human infections with CIVs have been reported to date, these viruses could pose a zoonotic risk. In these studies, the National Institutes of Allergy and Infectious Diseases (NIAID) Centers of Excellence for Influenza Research and Surveillance (CEIRS) network collaboratively demonstrated that CIVs replicated in some primary human cells and transmitted effectively in mammalian models. While people born after 1970 had little or no pre-existing humoral immunity against CIVs, the viruses were sensitive to existing antivirals and we identified a panel of H3 cross-reactive human monoclonal antibodies (hmAbs) that could have prophylactic and/or therapeutic value. Our data predict these CIVs posed a low risk to humans. Importantly, we showed that the CEIRS network could work together to provide basic research information important for characterizing emerging influenza viruses, although there were valuable lessons learned
Surface seawater distributions of inorganic carbon and nutrients around the Galapagos Islands: results from the PlumEx experiment using automated chemical mapping
During the second leg (PlumEx) of the 1993 IRONEX cruise, the partial pressure of CO
2 and the concentrations of nitrate and silicate in the surface waters around the GalapĂĄgos Islands were continuously measured using automated underway systems. Based on salinity-versus-constituent mixing diagrams, physical mixing processes dominate the pCO
2 and nutrient distributions upstream of the GalĂĄpagos Islands. Downstream of the islands, slight removal of nitrate and CO
2 can be discerned because of the high resolution of the underway measurements. The high spatial resolution of the underway measurements allowed evaluation of fine features such as sharp fluorescence peaks on the âwarmâ side of frontal boundaries. In the waters immediately adjacent to Fernandina and Isabela islands (Bolivar channel), dramatic drawdown of pCO
2 and nutrients was measured, coincident with the highest measured levels of iron (3 nM) and chlorophyll (>13
ÎŒg
l
-1) (Martin et al., 1994). The nearly constant alkalinity of the waters was combined with the measured pCO
2 to calculate total carbon dioxide in the waters. Based on mixing diagrams, the ratio of ÎTCO
2 to ÎNO
-
3 was found to be highly variable, ranging from approximately 6.4 to >10 in the waters near Isabela Island. The ratio of ÎTCO
2 to ÎNO
-
3 is approximately 8.5 in the waters west of the GalĂĄpagos where slight removal of nitrate and TCO
2 occurs. In these waters, the physical process of mixing and CO
2 degassing due to warming of the water becomes significant relative to the biological uptake and the ratio is driven higher
Biogeochemical Sensor Performance in the SOCCOM Profiling Float Array
The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program has begun deploying a large array of biogeochemical sensors on profiling floats in the Southern Ocean. As of February 2016, 86 floats have been deployed. Here the focus is on 56 floats with quality-controlled and adjusted data that have been in the water at least 6 months. The floats carry oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter sensors. The raw data generated by these sensors can suffer from inaccurate initial calibrations and from sensor drift over time. Procedures to correct the data are defined. The initial accuracy of the adjusted concentrations is assessed by comparing the corrected data to laboratory measurements made on samples collected by a hydrographic cast with a rosette sampler at the float deployment station. The long-term accuracy of the corrected data is compared to the GLODAPv2 data set whenever a float made a profile within 20 km of a GLODAPv2 station. Based on these assessments, the fleet average oxygen data are accurate to 1â±â1%, nitrate to within 0.5â±â0.5 ”mol kgâ1, and pH to 0.005â±â0.007, where the error limit is 1 standard deviation of the fleet data. The bio-optical measurements of chlorophyll fluorescence and optical backscatter are used to estimate chlorophyll a and particulate organic carbon concentration. The particulate organic carbon concentrations inferred from optical backscatter appear accurate to with 35 mg C mâ3 or 20%, whichever is larger. Factors affecting the accuracy of the estimated chlorophyll a concentrations are evaluated
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Biogeochemical Sensor Performance in the SOCCOM Profiling Float Array
The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program has begun deploying a large array of biogeochemical sensors on profiling floats in the Southern Ocean. As of February 2016, 86 floats have been deployed. Here the focus is on 56 floats with quality-controlled and adjusted data that have been in the water at least 6 months. The floats carry oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter sensors. The raw data generated by these sensors can suffer from inaccurate initial calibrations and from sensor drift over time. Procedures to correct the data are defined. The initial accuracy of the adjusted concentrations is assessed by comparing the corrected data to laboratory measurements made on samples collected by a hydrographic cast with a rosette sampler at the float deployment station. The long-term accuracy of the corrected data is compared to the GLODAPv2 data set whenever a float made a profile within 20 km of a GLODAPv2 station. Based on these assessments, the fleet average oxygen data are accurate to 1â±â1%, nitrate to within 0.5â±â0.5 ”mol kgâ1, and pH to 0.005â±â0.007, where the error limit is 1 standard deviation of the fleet data. The bio-optical measurements of chlorophyll fluorescence and optical backscatter are used to estimate chlorophyll a and particulate organic carbon concentration. The particulate organic carbon concentrations inferred from optical backscatter appear accurate to with 35 mg C mâ3 or 20%, whichever is larger. Factors affecting the accuracy of the estimated chlorophyll a concentrations are evaluated
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Characterizing Emerging Canine H3 Influenza Viruses.
The continual emergence of novel influenza A strains from non-human hosts requires constant vigilance and the need for ongoing research to identify strains that may pose a human public health risk. Since 1999, canine H3 influenza A viruses (CIVs) have caused many thousands or millions of respiratory infections in dogs in the United States. While no human infections with CIVs have been reported to date, these viruses could pose a zoonotic risk. In these studies, the National Institutes of Allergy and Infectious Diseases (NIAID) Centers of Excellence for Influenza Research and Surveillance (CEIRS) network collaboratively demonstrated that CIVs replicated in some primary human cells and transmitted effectively in mammalian models. While people born after 1970 had little or no pre-existing humoral immunity against CIVs, the viruses were sensitive to existing antivirals and we identified a panel of H3 cross-reactive human monoclonal antibodies (hmAbs) that could have prophylactic and/or therapeutic value. Our data predict these CIVs posed a low risk to humans. Importantly, we showed that the CEIRS network could work together to provide basic research information important for characterizing emerging influenza viruses, although there were valuable lessons learned