QA/QC: Yield tracers will be exchanged with other radiochemists. For intercalibration of Th, Pb and Po the radiochemists on different cruises have agreed to analyze deep water samples at each common station from a mutually agreed upon depth. For Pb and Po we will also use the Stony Brook sediment sample. We will compare particulate isotopes using samples from the Bishop pump and whole bottle filtration from the same depths. We will analyze isotopes on both the Murray/Newton and Hedges et al. traps for a comparison of trap fluxes.
Sediment trap samples will be analyzed for POC, CaCO, PN, PP, opal, chlorophyll, phaeopigments, HPLC pigments, major elements, trace elements, Th, Pb, Po, C (Quay) and N (Altabet). Supernatant solutions will be analyzed for nutrients, DOC and DIC in collaboration with other shipboard participants. Trace metals will be analyzed on the supernatant of the trace metal traps. Carbon and nitrogen will be analyzed on a Leeman Labs CHN analyzer, phosphorus by standard colorimetric techniques after combustion at 450°C and extraction into 0.5 M HCl (HOTS Protocols, 1990) and opal by colorimetric analyses following extraction into 0.5 % NaCO (Paasche, 1980, Limnology and Oceanography, 25:474--480). Chlorophyll and phaeopigments will be analyzed by standard fluorometric techniques. HPLC samples will be frozen in liquid nitrogen and returned to the lab for analyses. Major and trace elements will be analyzed by standard atomic absorption techniques (Jannasch, 1990, Ph.D. Thesis, University of Washington). The methods for radioisotopes were discussed above. Our techniques follow those given in JGOFS Report No. 9 for POC, PN, pigments and chlorophyll. No recommendations have been made for the other analyses.
QA/QC: Several opportunities will be used for intercalibration. We will trade samples with Bishop, Leinen, Dymond/Collier for comparison of major and minor element analyses. Samples will be shared with Bidigare for HPLC pigment analyses. The Hedges et al. traps will be analyzed for isotopes, pigments and carbon/nitrogen. The latter will be an intercalibration with Hedges. Carbon/nitrogen will be analyzed on aliquots from several different MLML traps at each depth to determine the variability. Experiments are in progress to test the best way to remove CaCO for organic carbon analyses. Blanks for all elements will be determined using closed traps processed with the samples.