<div><p>All analytical and sampling methodologies are described in Burkhardt et al. (2014). However, summary of most relevant methods are included here:</p>
<p>To explore the relationship between POM source and remineralization rates and stoichiometry, the investigators conducted a suite of on-deck incubation experiments in the North Pacific Subtropical Gyre (NPSG) in March of 2011 near Station ALOHA. 20-L aliquots of seawater were collected from the 75-m depth horizon at Station ALOHA. Immediately after collection, seawater was stored in the dark in an incubator continually flushed with surface seawater for ~72 hours. Dried POM material (cultured Trichodesmium IMS 101, “TRICHO”, Prochlorococcus MED4, “PRO”, T. weissflogii, “DIATOM” and the natural POM from the Oregon coast, “OR-POM”) was added to the carboys with aged Station ALOHA seawater. Each treatment was prepared in duplicate except for the OR-POM. Concentrations of ammonium (NH4) and SRP were obtained every 5 min for roughly the first half hour following POM addition to capture any solubilization trends. This initial phase was followed by discrete sampling every 3 hours. Nutrient samples were run at OSU, NMR samples were run at the University of California, Santa Cruz.</p>
<p>Nutrients were analyzed using flow-through colorimetric methods on a Technicon Auto Analyzer II. SRP was analyzed using the phosphomolybdic acid reduction; ammonium (NH4) was measured by the indophenol blue method (Gordon et al., 1993); and nitrate + nitrite (N+N) was analyzed using the cadmium reduction method of Armstrong et al. (1967). Detection limits were 55 nmol L-1 for SRP, 22 nmol L-1 for NH4, and 8 nmol L-1 for N+N. Total dissolved P and N (TDP and TDN, respectively) were determined by the alkaline persulfate oxidation method (Valderrama, 1981) using a 1:10 oxidant to sample ratio. Dissolved organic P (DOP) and N (DON) were calculated as the difference of TDP and SRP and TDN less the sum of NH4+ + NO3- + NO2-, respectively.</p>
<p>Particulate C, N, and P content of each POM type was determined by collecting a subsample of the biomass onto combusted GFF filters, wrapping in foil, flash freezing, and storing at -80 degrees C. The filters were then thawed and dried at 60 degrees C overnight, folded into tin and silver boats, and run on a Carlo-Erba C/N Analyzer for particulate C (PC) and N (PN) content (Sharp (1974). For particulate P (PP) analyses samples were thawed and combusted at 450 degrees C for 4.5 hours, then extracted with 0.15 M HCl for 1 hour at 60 degrees C. PP was then analyzed as SRP in a 1.0 cm cell at 880 nm following Strickland and Parsons (1972).</p>
<p>Molecular characterization of PP compounds was performed using subsamples of each POM type with 31P nuclear magnetic resonance (NMR) spectral analysis as per Cade-Menun et al. (2005). Samples were freeze-dried, extracted with a 25-mL solution of 0.25M NaOH 0.05M Na2EDTA for 4h, and then centrifuged. 1-mL aliquots of the supernatant and digested residue samples were analyzed for P concentrations via inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the extracted P and fraction that was not extracted. The remaining supernatant was analyzed for 31P-NMR spectroscopy on a 600 MHz Varian Unity INOVA spectrometer equipped with a 10mm broadband probe at 20 degrees C and a 90 degrees pulse. Compounds were identified by their chemical shifts (ppm) relative to an external orthophosphoric acid standard. After standardizing the orthophosphate peak in all samples to 6 ppm, peak assignments were based on Tebby and Glonek (1991) Cade-Menun and Preston (1996) and Turner et al. (2003b,c). Peak areas were calculated by integration of spectra processed with a 5 Hz line broadening, using NUTS software (Acorn NMR Inc.) as described in Paytan et al., (2003). Finally, the relative contribution of surface-adsorbed P was assessed for remaining TRICHO and DIATOM POM samples via the oxalate rinse method described in Fu et al. (2005); not enough material remained from PRO and OR-POM for similar analyses.</p></div>
Time-series of nutrient measurements following addition of Prochlorococcus derived POM to seawater collected at Station ALOHA.
<div><p>Time-series of nutrient measurements following addition of<em> Prochlorococcus</em> derived POM to seawater collected at Station ALOHA. Data published in Figure 1 in Burkhardt et al. (2014).</p>
<p><em>Related Publications and References:</em><br />
Burkhardt, B., K. S. Watkins-Brandt, D. Defforey, A. Paytan and A. E. White. 2014. Remineralization of phytoplankton-derived organic matter by natural populations of heterotrophic bacteria. <em>Marine Chemistry </em>162. doi: <a href="https://dx.doi.org/10.1016/j.marchem.2014.03.007" target="_blank">10.1016/j.marchem.2014.03.007</a></p>
<p>See Related Datasets:<br /><a href="http://www.bco-dmo.org/dataset/557396">Controls</a><br /><a href="http://www.bco-dmo.org/dataset/558209">Killed Controls</a><br /><a href="http://www.bco-dmo.org/dataset/557070">Trichodesmium</a><br /><a href="http://www.bco-dmo.org/dataset/557137">Diatoms</a><br /><a href="http://www.bco-dmo.org/dataset/557206">OR POM</a><br /><a href="http://www.bco-dmo.org/dataset/557470">Tricho NMR</a><br /><a href="http://www.bco-dmo.org/dataset/557572">Diatom NMR</a></p></div>
Prochlorococcus Remineralization Exp
<div><p>All data processing is described in Burkhardt et al. (2014). In general, data processing for nutrients involved conversion of raw absorbance data to nutrient concentrations using standard curves.</p>
<p>BCO-DMO processing:<br />
- Re-formatted date and time fields; added ISO_DateTime_Local.<br />
- Replaced blanks (missing data) and 'NaN' with 'nd' to indicate 'no data'.<br />
- Modified parameter names to conform with BCO-DMO naming conventions.<br />
</p></div>
557179
Prochlorococcus Remineralization Exp
2015-04-28T14:51:25-04:00
2015-04-28T14:51:25-04:00
2023-07-07T16:10:26-04:00
urn:bcodmo:dataset:557179
Time-series of nutrient measurements following addition of Prochlorococcus derived POM to seawater samples collected at Station ALOHA on R/V Kilo Moana cruise KM1110 in the North Pacific Subtropical Gyre in 2011
false
White, A. E., Paytan, A. (2015) Time-series of nutrient measurements following addition of Prochlorococcus derived POM to seawater samples collected at Station ALOHA on R/V Kilo Moana cruise KM1110 in the North Pacific Subtropical Gyre in 2011. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 28 April 2015) Version Date 2015-04-28 [if applicable, indicate subset used]. http://lod.bco-dmo.org/id/dataset/557179 [access date]
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28 April 2015
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2015-04-28
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