Methods are summarized below. Detailed methods for all data collected as part of this study can be found in the publications arising from this study (references given below).
On each BATS cruise, aquasi-lagrangian sampling scheme is employed. An in situ primary productivity array is deployed from dawn to dusk. The biogeochemistry and biological parameters reported in this data were measured from Niskin bottle water samples.
Bacterial production was measured using [3H-methyl] thymidine incorporation and converted to carbon-based bacterial production using standard equations. Bacterial abundance was determined using DAPI stained epifluorescence microscopy. Pico-autotrophs were identified as either Synechococcus and Prochlorococcus.
Samples for NO3/NO2, NO2 and PO4 are filtered and frozen (-20 degrees C) in HDPE bottles until analysis. Total organic carbon (TOC) and total nitrogen were determined using high temperature combustion techniques. Total phosphorus concentrations are quantified using a high temperature/persulfateoxidation technique. Particulate organic carbon (POC) and nitrogen (PON) samples were filtered on precombusted Whatman GF/F filters and frozen until analysis on an elemental analyzer. Particulate phosphorus samples were analyzed using an ash-hydrolysis method with oxidation efficiency and standard recovery checks.
Sample QA/QC procedures followed those given in the associated manuscripts. At the point of collection, any leaking niskin bottles were noted on the master cast sheets and samples were taken from a different niskin fired at the same depth as the leaking bottle. No data are reported for leaking Niskin bottles. During sample analysis, certified standards, where available, were carefully examined to ensure that they were consistent with expectations for accuracy and precision. If no obvious error or problem was found, the data were considered OK and in the range of environmental data that this study hoped to observe.
Sample accuracy was assessed by using certified standards, for those measurements where standards are available. Certified standards were run with each analytical run and compared to long term control charts for respective analyses. For those analyses where there are no standards (e.g., flow cytometric cell counts) data were assessed for reasonableness based upon extensive experience of the PI’s.
Detailed information on analyses:
Lomas, M.W., Burke, A., Lomas, D.A., Bell, D.W., Shen, C., Ammerman, J.W., Dyhrman, S.T. 2010. Sargasso Sea phosphorus biogeochemistry: An important role for dissolved organic phosphorus (DOP). Biogeosciences 7: 695-710. doi: 10.5194/bg-7-695-2010
Lomas, M.W., Bates, N.R., Johnson, R.J., Knap, A.H., Steinberg, D.K., Carlson, C.A. 2013. Two decades and counting: overview of 24-years of sustained open ocean biogeochemical measurements. Deep Sea Research II doi: 10.1016/j.dsr2.2013.01.008.
References:
Casey, J.R., Aucan, J.P., Goldberg, S.R., and Lomas, M.W. 2013. Changes in partitioning of carbon amongst photosynthetic pico- and nano-plankton groups in the Sargasso Sea in response to changes in the North Atlantic Oscillation. Deep Sea Research II doi: 10.1016/j.dsr2.2013.02.002
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