|Rose, Julie||National Oceanic and Atmospheric Administration (NOAA-Milford)||Principal Investigator|
|Hutchins, David A.||University of Southern California (USC)||Co-Principal Investigator|
|Kinkade, Danie||Woods Hole Oceanographic Institution (WHOI BCO-DMO)||BCO-DMO Data Manager|
Experiments were conducted during the CORSACS (Controls On Ross Sea Algal Community Structure) expedition in November 2006 to the Ross Sea, Antarctica, onboard the RVIB Nathaniel B. Palmer (cruise NBP-0608). Water was collected at 76 50' S, 173 47' E using a trace metal clean towed-intake surface water Teflon diaphragm pumping system (Bruland et al., 2005). Sea surface temperature at this location was -1.5 deg C at the time of water collection. Water was prescreened through acid-washed 200 um Nitex mesh to eliminate large zooplankton and collected into a 50-L mixing carboy. Collected water was gently mixed and dispensed into 24 4.5-L acid washed trace metal clean clear polycarbonate bottles for incubation. Four treatments were used with six replicates per treatment. Bottles were incubated in two temperature controlled deck-board incubators housed in deck vans under halogen lights (Feng et al., 2009; Hare et al., 2007). Irradiance was 2000 uE m2 s-1 without screening. Incubators were screened with neutral density filter and measured irradiances in the four treatments were:
Low light, low temperature (LLLT): 61 uE m2 s-1
Low light, high temperature (LLHT): 45 uE m2 s-1
High light, low temperature (HLLT): 321 uE m2 s-1
High light, high temperature (HLHT): 320 uE m2 s-1
One incubator was maintained at 0 deg C, while the temperature in the other was gradually increased to 4 deg C over the course of 24 h. Bottles were incubated for eight days. All sampling occurred under a laminar flow hood using trace metal clean techniques.
Bruland, K.W., E.L. Rue, G.J. Smith, and G.R. DiTullio. 2005. Iron, macronutrients and diatom blooms in the Peru upwelling regime: brown and blue waters of Peru. Marine Chemistry 93: 81-103.
Feng, Y., C.E. Hare, K. Leblanc, G.R. DiTullio, P.A. Lee, S.W. Wilhelm, J. Sun, J.M. Rose, N. Nemcek, I. Benner, and D.A. Hutchins. 2009. The effects of increased pCO2 and temperature on the North Atlantic Spring Bloom: I. The phytoplankton community and biogeochemical response. Marine Ecology Progress Series 388: 13-25.
Hare, C.E., K. Leblanc, G.R. DiTullio, R.M. Kudela, Y. Zhang, P.A. Lee, S.F. Riseman, and D.A. Hutchins. 2007. Consequences of increased temperature and CO2 for phytoplankton community structure in the Bering Sea. Marine Ecology Progress Series 352: 9-16.
Total dissolved Fe concentrations were filtered through 0.4um track-etched polycarbonate filters (Nuclepore Whatman) and acidified to pH 1.7 with 4 mL -1 sub-boiled distilled HCl. Total dissolved Fe was measured using adsorptive cathodic stripping voltammetry (ACSV) (Buck et al., 2007). A 5mM salicylaldoxime (SA: Aldrich, ≥ 98%) solution was first prepared in quartz-distilled methanol (Q-MeOH) and stored in the refrigerator. A final concentration of 25uM SA was used for total dissolved Fe measurements. A 1.5 M borate buffer was made in 0.4 mol L quartz-distilled ammonium hydroxide (Q-NH4OH) as previously described (Ellwood and Van den Berg, 2000). The voltammetric system consisted of Princeton Applied Research (PAR) 303A interfaced with a computer-controlled AutolabII potentiostat/galvanostat (Eco Chemie). The working electrode was a “large” mercury drop (2.8 mm2), the reference electrode was Ag: saturated AgCl, saturated KCl, and the counterelectrode was a platinum wire. Acidified samples were microwaved 2×15 s at 1100W to release dissolved Fe from ambient organic ligands (Bruland et al., 2005), neutralized once with cool 1 mol L -1 QNH4OH, and buffered to pH 8.2 with the borate buffer. Once buffered, Fe and SA additions were made and following ACSV analysis Fe concentrations were determined from a linear regression of the standard addition curve. The detection limit for the ACSV method is 0.02 nmol L -1, calculated from three times the standard deviation of a 0.05 nmol L -1 Fe addition, as no peak is observed in either Milli-Q or ultraviolet (UV)-oxidized seawater (from which trace metals and metal-chelating organic ligands are removed from seawater; (Donat and Bruland, 1988) at deposition times of up to 600 s. Deposition times for sample analyses here were between 60 and 400 s, depending on ambient Fe concentrations. The precision of this technique for replicate samples is less than 4%.
BCO-DMO Processing Notes:
- File was sorted by treatment
- Added lat,lon values of original water sampling location to file
- Added BCO-DMO header lines
- Parameter names were edited to conform with BCO-DMO convention
- Added 'nd' for missing data
|lat||Latitude component of geographic position where water was sampled.||decimal degrees|
|lon||Longitude component of geographic position where water was sampled.||decimal degrees|
|treatment||Experimental conditions varied during the experiment. Four treatments were used: Low light, low temperature (LLLT); Low light, high temperature (LLHT); High light, low temperature (HLLT); High light, high temperature (HLHT)||dimensionless|
|day||Sampling day during experiment. The experiment was conducted during November, 2006.||dimensionless|
|bottle||Experimental bottle number.||dimensionless|
|Fe||Dissolved iron concentration.||nM|
|error_analytic||Analytical error in iron measurement||nM|
|Dataset-specific Instrument Name|| |
|Generic Instrument Name|| |
|Dataset-specific Description|| |
The voltammetric system consisted of Princeton Applied Research (PAR) 303A interfaced with a computer-controlled AutolabII potentiostat/galvanostat (Eco Chemie). The working electrode was a “large” mercury drop (2.8mm2), the reference electrode was Ag: saturated AgCl, saturated KCl, and the counterelectrode was a platinum wire.
|Generic Instrument Description|| |
Instruments that obtain information about an analyte by applying a potential and measuring the current produced in the analyte.
RVIB Nathaniel B. Palmer
|Start Date|| |
|End Date|| |
This was the second of two Controls of Ross Sea Algal Community Structure (CORSACS) project cruises and was funded by the NSF Office of Polar Programs. The NBP0608 cruise was conducted in the Ross Sea in November and December 2006, ca. 65.21°S-78.65°S, 164.98°E-164.70°W. Related files: Cruise track map (PDF file) Related Sites: MGDS catalog: http://www.marine-geo.org/tools/search/entry.php?id=NBP0608