Dataset: GP16 DI Water Soluble Aerosols

Data have been corrected for field and analytical blank. All reported trace element concentration values have been normalized to the volume of air filtered during that sample collection. Each sample collection period (n = 17) produced 36 replicate filters. Three of those filters were extracted with ultrapure DI water producing three replicate measurements. In the majority of cases, the three replicates agreed well. In a small number of cases, one replicate differed from the others and these data are marked as described in the datasheet. In all cases, data from the three replicates were averaged and reported along with the standard deviation.

Results of analysis of NASS-6 certified reference materials are available (PDF).

Quality flag codes:
BDL = below detection limit;
0 = No QC performed;
1 = Good data;
2 = Probably good data;
3 = Probably bad data that is potentially correctable;
4 = Bad data;
5 = Value changed;
6 = Sample < blank;
8 = Interpolated value;
​9 = Missing value.

BCO-DMO Processing:
- modified parameter names to conform with BCO-DMO naming convetions;
- replaced missing data and "no value" with "nd";
- added ISO_DateTime fields using date and time fields provided in original dataset;
- joined to the BCO-DMO master file to add station, event, etc. fields;
- 13 June 2017: changed parameter original named "nss_SO4_DI_S_Conc_Aerosol" to "SO4_DI_S_Conc_Aerosol"; re-named associated variance and QF columns as well.

Additional 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.