Trace-metals from CTD casts and underway water samples collected during the R/V Hugh R. Sharp cruise HRS1414 in the Mid and South-Atlantic Bight in August of 2014 (DANCE project)

Website: https://www.bco-dmo.org/dataset/734324
Data Type: Cruise Results
Version: 1
Version Date: 2018-04-25

Project
» Collaborative Research: Impacts of atmospheric nitrogen deposition on the biogeochemistry of oligotrophic coastal waters (DANCE)
ContributorsAffiliationRole
Sedwick, Peter N.Old Dominion University (ODU)Principal Investigator, Contact
Mulholland, MargaretOld Dominion University (ODU)Co-Principal Investigator
Najjar, RaymondPennsylvania State University (PSU)Co-Principal Investigator
York, Amber D.Woods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Abstract
Dissolved iron, nitrate+nitrite, ammonium, and phosphate were measured from CTD bottle samples, and underway water samples collected with a towfish system during the R/V Hugh R. Sharp cruise HRS1414 in the Mid and South-Atlantic Bight in August of 2014. This dataset also includes temperature, salinity, chlorophyll fluorescence, depth, latitude, and longitude.


Coverage

Spatial Extent: N:38.6456 E:-71.1548 S:33.628 W:-74.4656
Temporal Extent: 2014-08-01 - 2014-08-10

Methods & Sampling

[The following methodology applies where dataset parameter "sample_source" is "UNDERWAY"]

Near-surface sample collection: Near-surface (~4 m depth) seawater was collected whilst underway at ~5 knots using a trace-metal clean towfish system [Sedwick et al., 2011]. The subsamples for analysis of DFe, NO3+NO2, PO4 were taken directly from the towfish line, after filtration through a 0.8/0.2 µm AcroPak Supor filter capsule (Pall), in acid-cleaned 125 mL low-density polyethylene bottles (Nalgene) for shore-based DFe determinations, and 60 mL polypropylene tubes (Falcon) for shipboard NO3+NO2, PO4 and NH4 analyses.

Near-surface underway measurements: Continuous underway measurements of near-surface seawater temperature, salinity and chlorophyll fluorescence were made using the ship's underway seawater supply, which is pumed from a water depth of ~1m. The data presented correspond to the approximate times when subsamples were collected from the towfish seawater outlet for measurements of dissolved iron and macronutrients (see above).

DFe: Filtered seawater samples were acidified at-sea to pH ~1.8 with Fisher Optima grade ultrapure hydrochloric acid, and then stored at room temperature until post-cruise analysis at Old Dominion University. Dissolved iron was determined by flow injection analysis with colorimetric detection after in-line preconcentration on resin-immobilized 8-hydroxyquinoline (Sedwick et al., 2015), using a method modified from Measures et al. (1995). Analyses were performed on a volumetric basis, so concentrations are reported in units of nanomole liter-1 (nM). Analytical precision is estimated from multiple (separate-day) determinations of the SAFe seawater reference materials, which yield uncertainties (expressed as one relative standard deviation on the mean, or one sigma) of ~15% at the concentration level of SAFe S seawater (0.090 nM), and ~10% at the concentration level of SAFe D2 seawater (0.90 nM). The analytical limit of detection is estimated as the DFe concentration equivalent to a peak area that is three times the standard deviation on the zero-loading blank (manifold blank), which yields an estimated detection limit below 0.04 nM (Bowie et al., 2004). Blank contributions from the ammonium acetate sample buffer solution (added on-line during analysis) and hydrochloric acid (added after collection) are negligible.

NO3+NO2: Dissolved nitrate and nitrite was determined at sea using an Astoria Pacific nutrient autoanalyzer using standard colorimetric methods with an estimated detection limit of 0.14 µM (Parsons et al., 1984; Price and Harrison, 1987). In surface waters, nitrate and nitrite were determined using the same autoanalyzer equipped with a liquid waveguide capillary cell (World Precision Instruments) (Zhang, 2000) to achieve an estimated detection limit of 0.02 µM.

PO4: Dissolved phosphate was determined at sea using an Astoria Pacific nutrient autoanalyzer using standard colorimetric methods with an estimated detection limit of 0.03 µM (Parsons et al., 1984; Price and Harrison, 1987).

NH4: Dissolved ammonium was determined at sea using the manual orthophthaldialdehyde method (Holmes et al., 1999), with an estimated detection limit of 10 nM.

Temperature: Underway temperature was measured using a conductivity-temperature-depth sensor (SBE 45, SeaBird Electronics).

Salinity: Underway salinity was calculated from in-situ conductivity, as measured using a conductivity-temperature-depth (CTD) sensor (SBE 45, SeaBird Electronics).

Fluorescence: Underway chlorophyll fluorescence was measured using a Turner AU10 fluorometer.

[The following methodology applies where dataset parameter "sample_source" is "CTD"]

Water column sample collection and in-situ measurements: Water-column samples for analysis of dissolved iron, nitrate plus nitrite, phosphate and ammonium, and continuous profiles of temperature, salinity and chlorophyll fluorescence were collected using a trace-metal clean conductivity-temperature-depth sensor (SBE 19 plus, SeaBird Electronics) mounted on a custom-built trace-metal clean carousel (SeaBird Electronics) fitted with custom-modified 5-L Teflon-lined external-closure Niskin-X samplers (General Oceanics), deployed on a Kevlar line. Upon recovery, the Niskin-X samplers were transferred into a shipboard Class-100 clean laboratory, where seawater was filtered through pre-cleaned 0.2-µm pore AcroPak Supor filter capsules (Pall) into acid-cleaned 125 mL low-density polyethylene bottles (Nalgene) for shore-based dissolved iron determinations, and 60 mL polypropylene tubes (Falcon) for shipboard nutrient analyses.

DFe: Filtered seawater samples were acidified at-sea to pH ~1.8 with Fisher Optima grade ultrapure hydrochloric acid, and then stored at room temperature until post-cruise analysis at Old Dominion University. Dissolved iron was determined by flow injection analysis with colorimetric detection after in-line preconcentration on resin-immobilized 8-hydroxyquinoline (Sedwick et al., 2015), using a method modified from Measures et al. (1995). Analyses were performed on a volumetric basis, so concentrations are reported in units of nanomole liter-1 (nM). Analytical precision is estimated from multiple (separate-day) determinations of the SAFe seawater reference materials, which yield uncertainties (expressed as one relative standard deviation on the mean, or one sigma) of ~15% at the concentration level of SAFe S seawater (0.090 nM), and ~10% at the concentration level of SAFe D2 seawater (0.90 nM). The analytical limit of detection is estimated as the DFe concentration equivalent to a peak area that is three times the standard deviation on the zero-loading blank (manifold blank), which yields an estimated detection limit below 0.04 nM (Bowie et al., 2004). Blank contributions from the ammonium acetate sample buffer solution (added on-line during analysis) and hydrochloric acid (added after collection) are negligible.

NO3+NO2: Dissolved nitrate and nitrite was determined at sea using an Astoria Pacific nutrient autoanalyzer using standard colorimetric methods with an estimated detection limit of 0.14 µM (Parsons et al., 1984; Price and Harrison, 1987). In surface waters, nitrate and nitrite were determined using the same autoanalyzer equipped with a liquid waveguide capillary cell (World Precision Instruments) (Zhang, 2000) to achieve an estimated detection limit of 0.02 µM.

PO4: Dissolved phosphate was determined at sea using an Astoria Pacific nutrient autoanalyzer using standard colorimetric methods with an estimated detection limit of 0.03 µM (Parsons et al., 1984; Price and Harrison, 1987).

NH4: Dissolved ammonium was determined at sea using the manual orthophthaldialdehyde method (Holmes et al., 1999), with an estimated detection limit of 10 nM.

Temperature: In-situ temperature was measured using a conductivity-temperature-depth sensor (SBE 19 plus, SeaBird Electronics).

Salinity: Salinity was calculated from in-situ conductivity, as measured using a conductivity-temperature-depth (CTD) sensor (SBE 19 plus, SeaBird Electronics).

Fluorescence: In-situ chlorophyll fluorescence was measured using a WET Labs ECO-FL(RT)D deep chlorophyll fluorometer with 125 μg L-1 range mounted on the CTD rosette.


Data Processing Description

CTD data (temperature, salinity) were processed using SeaSoft processing software (SeaBird Electronics).

BCO-DMO Data Manager Processing Notes:
* added a conventional header with dataset name, PI name, version date
* modified parameter names to conform with BCO-DMO naming conventions
* combined two Excel files, one for the underway data and one for the ctd data into one dataset.
* missing data shown as default missing data identifier "nd" for "no data" or "BDL" for below detection limit.


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Data Files

File
trace_metals_toplevel.csv
(Comma Separated Values (.csv), 10.66 KB)
MD5:4439f7648b40332c64ef59cca7390b97
Primary data file for dataset ID 734324

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Related Publications

Bowie, A. R., Sedwick, P. N., & Worsfold, P. J. (2004). Analytical intercomparison between flow injection-chemiluminescence and flow injection-spectrophotometry for the determination of picomolar concentrations of iron in seawater. Limnology and Oceanography: Methods, 2(2), 42–54. doi:10.4319/lom.2004.2.42
Methods
Holmes, R. M., Aminot, A., Kérouel, R., Hooker, B. A., & Peterson, B. J. (1999). A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Canadian Journal of Fisheries and Aquatic Sciences, 56(10), 1801–1808. doi:10.1139/f99-128
Methods
Measures, C. I., Yuan, J., & Resing, J. A. (1995). Determination of iron in seawater by flow injection analysis using in-line preconcentration and spectrophotometric detection. Marine Chemistry, 50(1-4), 3–12. doi:10.1016/0304-4203(95)00022-j
Methods
Mulholland, M. R., Bernhardt, P. W., Heil, C. A., Bronk, D. A., & O’Neil, J. M. (2006). Nitrogen fixation and release of fixed nitrogen by Trichodesmium spp. in the Gulf of Mexico. Limnology and Oceanography, 51(4), 1762–1776. doi:10.4319/lo.2006.51.4.1762
General
Parsons, T. R., Y. Maita, and C. M. Lalli. "A Manual of Chemical and Biological Methods of Seawater Analysis", Pergamon Press (1984). ISBN: 9780080302874
Methods
Price, N. M., & Harrison, P. J. (1987). Comparison of methods for the analysis of dissolved urea in seawater. Marine Biology, 94(2), 307–317. doi:10.1007/bf00392945 https://doi.org/10.1007/BF00392945
Methods
Sedwick, P. ., Sohst, B. M., Ussher, S. J., & Bowie, A. R. (2015). A zonal picture of the water column distribution of dissolved iron(II) during the U.S. GEOTRACES North Atlantic transect cruise (GEOTRACES GA03). Deep Sea Research Part II: Topical Studies in Oceanography, 116, 166–175. doi:10.1016/j.dsr2.2014.11.004
Methods
Sedwick, P. N., Bernhardt, P. W., Mulholland, M. R., Najjar, R. G., Blumen, L. M., Sohst, B. M., Sookhdeo, C., & Widner, B. (2018). Assessing Phytoplankton Nutritional Status and Potential Impact of Wet Deposition in Seasonally Oligotrophic Waters of the Mid‐Atlantic Bight. In Geophysical Research Letters (Vol. 45, Issue 7, pp. 3203–3211). American Geophysical Union (AGU). https://doi.org/10.1002/2017gl075361 https://doi.org/10.1002/2017GL075361
General
Sedwick, P. N., Marsay, C. M., Sohst, B. M., Aguilar-Islas, A. M., Lohan, M. C., Long, M. C., … DiTullio, G. R. (2011). Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf. Journal of Geophysical Research, 116(C12). doi:10.1029/2010jc006553
Methods
Welschmeyer, N. A. (1994). Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments. Limnology and Oceanography, 39(8), 1985–1992. doi:10.4319/lo.1994.39.8.1985
General
Zhang, J.-Z. (2000). Shipboard automated determination of trace concentrations of nitrite and nitrate in oligotrophic water by gas-segmented continuous flow analysis with a liquid waveguide capillary flow cell. Deep Sea Research Part I: Oceanographic Research Papers, 47(6), 1157–1171. doi:10.1016/s0967-0637(99)00085-0 https://doi.org/10.1016/S0967-0637(99)00085-0
Methods

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Parameters

ParameterDescriptionUnits
sample_sourceSource of sample water (CTD or UNDERWAY).  UNDERWAY samples were collected by a trace-metal clean towfish system (Sedwick et al., 2011) unitless
Sample_IDU​nique identifier for each water sample unitless
StationDANCE cruise station number unitless
DepthSample collection depth (below surface) meters (m)
DateLocal date (EST) of collection in format yyyy-mm-dd unitless
TimeLocal time (EST) of collection of sample/data in format HH:MM unitless
LatitudeLatitude of water sample, if source is CTD then this latitude is the start of the CTD cast decimal degrees
LongitudeLongitude of water sample, if source is CTD then this longitude is the start of the CTD cast decimal degrees
DfeDissolved iron concentration nanomoles per liter (nmol/L)
DFe_flagDissolved iron data quality flag. 2 (good), 3 (contamination suspected) unitless
NO3_NO2Dissolved nitrate plus nitrite concentration micromoles per liter (umol/L)
PO4Dissolved phosphate concentration micromoles per liter (umol/L)
NH4Dissolved ammonium concentration nanomoles per liter (nmol/L)
TempTemperature degrees Celsius (°C)
SalinitySalinity Practical salinity units (PSU)
FluorChlorophyll fluorescence volt


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Instruments

Dataset-specific Instrument Name
SBE 19 plus
Generic Instrument Name
CTD Sea-Bird
Dataset-specific Description
SBE 19 plus, SeaBird Electronics, calibrated by calibrated by SeaBird Electronics: CTD sensor (temperature and conductivity)
Generic Instrument Description
Conductivity, Temperature, Depth (CTD) sensor package from SeaBird Electronics, no specific unit identified. This instrument designation is used when specific make and model are not known. See also other SeaBird instruments listed under CTD. More information from Sea-Bird Electronics.

Dataset-specific Instrument Name
SBE 45, SeaBird Electronics
Generic Instrument Name
CTD Sea-Bird
Dataset-specific Description
SBE 45, SeaBird Electronics: CTD sensor (temperature and conductivity)
Generic Instrument Description
Conductivity, Temperature, Depth (CTD) sensor package from SeaBird Electronics, no specific unit identified. This instrument designation is used when specific make and model are not known. See also other SeaBird instruments listed under CTD. More information from Sea-Bird Electronics.

Dataset-specific Instrument Name
Turner AU10 fluorometer
Generic Instrument Name
Fluorometer
Dataset-specific Description
Fluorometer: in-situ chlorophyll fluorescence
Generic Instrument Description
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ.

Dataset-specific Instrument Name
: WET Labs ECO-FL(RT)D deep chlorophyll fluorometer
Generic Instrument Name
Fluorometer
Dataset-specific Description
WET Labs ECO-FL(RT)D deep chlorophyll fluorometer, calibrated by SeaBird Electronics: in-situ chlorophyll fluorescence
Generic Instrument Description
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ.

Dataset-specific Instrument Name
Shimadzu RF1501 (Spectrofluorophotometer)
Generic Instrument Name
Fluorometer
Dataset-specific Description
Spectrofluorophotometer: NH4
Generic Instrument Description
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ.

Dataset-specific Instrument Name
Astoria Pacific nutrient autoanalyzer
Generic Instrument Name
Nutrient Autoanalyzer
Dataset-specific Description
Macronutrient analysis: NO3+NO2, PO4
Generic Instrument Description
Nutrient Autoanalyzer is a generic term used when specific type, make and model were not specified. In general, a Nutrient Autoanalyzer is an automated flow-thru system for doing nutrient analysis (nitrate, ammonium, orthophosphate, and silicate) on seawater samples.

Dataset-specific Instrument Name
Shimadzu SPD-10AV
Generic Instrument Name
UV Spectrophotometer-Shimadzu
Dataset-specific Description
UV-visible spectrophotometric detector:  DFe
Generic Instrument Description
The Shimadzu UV Spectrophotometer is manufactured by Shimadzu Scientific Instruments (ssi.shimadzu.com). Shimadzu manufacturers several models of spectrophotometer; refer to dataset for make/model information.


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Deployments

HRS1414

Website
Platform
R/V Hugh R. Sharp
Start Date
2014-07-29
End Date
2014-08-16


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Project Information

Collaborative Research: Impacts of atmospheric nitrogen deposition on the biogeochemistry of oligotrophic coastal waters (DANCE)

Coverage: Offshore Mid-Atlantic Bight and northern South-Atlantic Bight between latitudes 31.60°N and 38.89°N, and longitudes 71.09°W and 75.16°W


NSF abstract:

Deposition of atmospheric nitrogen provides reactive nitrogen species that influence primary production in nitrogen-limited regions. Although it is generally assumed that these species in precipitation contributes substantially to anthropogenic nitrogen loadings in many coastal marine systems, its biological impact remains poorly understood. Scientists from Pennsylvania State University, William & Mary College, and Old Dominion University will carry out a process-oriented field and modeling effort to test the hypothesis that deposits of wet atmospheric nitrogen (i.e., precipitation) stimulate primary productivity and accumulation of algal biomass in coastal waters following summer storms and this effect exceeds the associated biogeochemical responses to wind-induced mixing and increased stratification caused by surface freshening in oligotrophic coastal waters of the eastern United States. To attain their goal, the researchers would perform a Lagrangian field experiment during the summer months in coastal waters located between Delaware Bay and the coastal Carolinas to determine the response of surface-layer biogeochemistry and biology to precipitation events, which will be identified and intercepted using radar and satellite data. As regards the modeling effort, a 1-D upper ocean mixing model and a 1-D biogeochemical upper-ocean will be calibrated by assimilating the field data obtained a part of the study using the adjoint method. The hypothesis will be tested using sensitivity studies with the calibrated model combined with in-situ data and results from the incubation experiments. Lastly, to provide regional and historical context for the field measurements and the associated 1-D modeling, linked regional atmospheric-oceanic biogeochemical modeling will be conducted.

Broader Impacts. Results from the study would be incorporated into class lectures for graduate courses on marine policy and marine biogeochemistry. One graduate student from Pennsylvania State University, one graduate student from the College of William and Mary, and one graduate and one undergraduate student from Old Dominion University would be supported and trained as part of this project.



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Funding

Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)
NSF Division of Ocean Sciences (NSF OCE)

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