The methodology is published in Church et al., (2012) and Baskaran et al. (2013) as well as given in the Sampling and Sample-handling Protocols for GEOTRACES Cruises (Cookbook).
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Chemical Procedures for the analysis of dissolved Po-210 and Pb-210 may be downloaded below under 'Supplemental Files'.
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We have conducted a large number of blanks to obtain high-quality data. We have also an archived water sample from the Atlantic and assessed the activities of Po-210 and Pb-210 in a known sample. We have developed an Excel Spreadsheet that includes all the corrections (both decay and in-growth) needed to get accurate data.
Details of all calculations are in Baskaran et al. (2013).
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BCO-DMO Processing:
\n- added conventional header with dataset name, PI name, version date
\n- renamed parameters to BCO-DMO standard
\n- added columns by joining the submitted data with an Events Master file - bottle and fish samples separated; parameter names revised
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Additional GEOTRACES Processing:
\nAs was done for the GEOTRACES-NAT data, BCO-DMO added standard US GEOTRACES information, such as the US GEOTRACES event number, to each submitted dataset lacking this information. To accomplish this, BCO-DMO compiled a 'master' dataset composed of the following parameters:
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cruise_id, EXPOCODE,SECT_ID, STNNBR, CASTNO, GEOTRC_EVENTNO, GEOTRC_SAMPNO, GEOTRC_INSTR, SAMPNO, GF_NO, BTLNBR, BTLNBR_FLAG_W, DATE_START_EVENT, TIME_START_EVENT, ISO_DATETIME_UTC_START_EVENT, EVENT_LAT, EVENT_LON, DEPTH_MIN, DEPTH_MAX, \u00a0BTL_DATE, BTL_TIME, BTL_ISO_DATETIME_UTC, BTL_LAT, BTL_LON, ODF_CTDPRS, SMDEPTH, FMDEPTH, BTMDEPTH, CTDPRS, CTDDEPTH.
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This added information will facilitate subsequent analysis and inter comparison of the datasets.
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Bottle parameters in the master file were taken from the GT-C_Bottle and ODF_Bottle datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the TN303 Event Log (version 30 Oct 2014). Where applicable, pump information was taken from the PUMP_Nuts_Sals dataset.
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A standardized BCO-DMO method (called \"join\") was then used to merge the missing parameters to each US GEOTRACES dataset, most often by matching on sample_GEOTRC or on some unique combination of other parameters.
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If the master parameters were included in the original data file and the values did not differ from the master file, the original data columns were retained and the names of the parameters were changed from the PI-submitted names to the standardized master names. If there were differences between the PI-supplied parameter values and those in the master file, both columns were retained. If the original data submission included all of the master parameters, no additional columns were added, but parameter names were modified to match the naming conventions of the master file.
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See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.