Dataset: GP16 Copper Speciation

Sample processing employed a one ligand model utilizing the ProMCC software described in Omanovic et al. 2015. The software provides a 95% confidence interval for uncertainties in the fitted parameter, these uncertainties are presented for samples without a duplicate titration. Samples with duplicate titrations are presented with average values for ligand concentration, logK, and free copper values initially determined by ProMCC. Averaged values for samples with duplicate titrations are presented with a standard deviation.

Dissolved copper concentration values were provided by Claire Till and Saeed Roshan, these values were used in ProMCC for ligand and logK value determinations and provided here for reference.

Quality flags:
The standard Ocean Data View qualifying flags were used (reference all flags at https://www.bodc.ac.uk/data/codes_and_formats/odv_format/):

1: Good Value: Good quality data value that is not part of any identified malfunction and has been verified as consistent with real phenomena during the quality control process. [Used for data with duplicate and with a percent error below 25%]

2: Probably Good Value: Data value that is probably consistent with real phenomena but this is unconfirmed or data value forming part of a malfunction that is considered too small to affect the overall quality of the data object of which it is a part. [Used when samples with duplicates have a percent error above 25%, also used for samples without duplicates]

3: Probably Bad Value: Data value recognized as unusual during quality control that forms part of a feature that is probably inconsistent with real phenomena. [Used when [Cu] was higher than expected]

4: Bad Value: An obviously erroneous data value.

5: Changed Value: Data value adjusted during quality control.

6: Value Below Detection Limit: The level of the measured phenomenon was too small to be quantified by the technique employed to measure it. The accompanying value is the detection limit for the technique or zero if that value is unknown.

7: Value in Excess: The level of the measured phenomenon was too large to be quantified by the technique employed to measure it. The accompanying value is the measurement limit for the technique.

8: Interpolated Value: This value has been derived by interpoloation from other values in the data object.

BCO-DMO Processing:
- modified parameter names to conform with BCO-DMO naming convetions (replaced ' symbol with "prime");
- replaced blanks (missing/no data) with "nd";
- joined to EPZT master events file;
- 23-Sept-2019: Moved data values for sample 10339 that were erroneosly in the BOTTLE columns (Cu_Cu_prime_D_CONC_BOTTLE_95pcnt_CI and Cu_Cu_prime_D_CONC_BOTTLE_95pcnt_CI) to the corresponding FISH columns.

Additional BCO-DMO GEOTRACES Processing:
As 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: 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,  BTL_DATE, BTL_TIME, BTL_ISO_DATETIME_UTC, BTL_LAT, BTL_LON, ODF_CTDPRS, SMDEPTH, FMDEPTH, BTMDEPTH, CTDPRS, CTDDEPTH.

This added information will facilitate subsequent analysis and inter comparison of the datasets.

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.

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.

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.

See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.