Dissolved Inorganic Nutrients (Cruise)
- Dissolved inorganic nutrients including 5 macro nutrients: silicate, phosphate, nitrate, nitrite, and ammonium from water column bottle samples collected during annual cruise along western Antarctic Peninsula, 1991 - 2019.
- The inorganic plant macronutrients dissolved phosphate, silicate, nitrate, nitrite and ammonium are the major sources of nutrition for phytoplankton growth in seawater (with sunlight and inorganic carbon). Macronutrient distributions reflect the large-scale circulation patterns in the oceans and are useful properties to delineate water masses. Dissolved inorganic nutrients samples are typically collected in every CTD/Rosette cast performed on the annual LTER cruises along the western Antarctic Peninsula. Water samples are analyzed for dissolved nutrients with recognized standard oceanographic protocols for nutrient autoanalyzers (continuous flow analyzers). In Antarctic waters, dissolved inorganic macronutrients are seldom depleted to limiting concentrations except during heavy prolonged phytoplankton blooms. This is due to the fact that phytoplankton growth is more often limited by light or iron, and to the short growing season.
- habitats, marine, ecology, measurements, nutrients, nitrate, inorganic nutrients, biogeochemistry, food webs, ecosystems, ice, decomposition, phytoplankton, Inorganic Matter
- LTER Data System Record
Main data table for dataset
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- General Methods
- Water from Go-Flo bottles was sub-sampled directly into acid washed 50ml Falcon tubes and stored at -70 degrees Celcsius until analysis on a Lachat QuikChem 8000 nutrient analyzer. Samples collected within the euphotic zone of the CTD cast were filtered through 0.45um polypropylene syringe-tip filters before freezing, all others were collected directly into the 50ml tubes.
- Analysis Methods and Protocols
- From 1991 to 2007 DIN samples were analyzed at the University of California at Santa Barbara Marine Science Institute Analytical Lab (http://msi.ucsb.edu/services/analytical-lab) using a Lachat Quickchem 8000 autoanalyzer. From 2007-13 samples were analyzed at the Marine Biological Laboratory (Woods Hole MA), also using a Lachat Quickchem 8000. Details of methods are available from http://www.lachatinstruments.com/applications/methods.asp. From 2014-2019, samples were analyzed at Lamont-Doherty using a SEAL Analytical AutoAnalyzer AA3 HR, Software version 6.10 (Mequon, WI), G-297-03 Rev 4 (Multitest MT19 for PO3−4 ), G-172-96 Rev 16 (Multitest MT 19 for NO-3 and NO−2 ), and G-177-96 Rev 11 (Multitest MT19 for H4SiO4). Standards used for the phosphate, nitrate + nitrite, and silicate analyses were potassium dihydrogen phosphate, potassium nitrate and sodium nitrite, and sodium metasilicate nonahydrate, respectively.
Our sampling and analytical protocols follow recent recommendations for time-series stations: Lorenzoni, L., Benway, H. M. (Editors), 2013. Report of Global intercomparability in a changing ocean: An international time-series methods workshop, November 28-30, 2012, Ocean Carbon and Biogeochemistry (OCB) Program and International Ocean Carbon Coordination Project (IOCCP), 59 pp.
- Sampling Methods
- Water samples are typically collected from all Niskin bottles on every CTD/Rosette cast performed during a cruise. Water samples are gravity-filtered through ashed GFF filters by inline filtration from the Niskin bottles, into new clean plastic 13-mL centrifuge tubes. Samples in tubes are frozen at -20C until return to the home laboratory in the USA for subsequent analysis.