Introduction
Salinity onboard is measured using a Fisher Model S66366 Refractometer. Higher concentration of salt in water results in more refraction of light through water. The amount of refraction of light through a sample on the refractometer can then be used to measure the salinity of the sample. The refractometer has scales for both specific gravity and ppt. The procedure used to measure salinity calibrates the refractometer with a seawater standard (IAPSO) to 35 ppt on the refractometer, although values are typically reported without units.
Calibration
- Rinse and clean the blue prism surface with ultrapure water onto it and then wiping dry.
- Add a drop of IAPSO standard seawater onto the blue prism surface. 50 uL from a pipette should work well.
- Close the clear prism lid and the water should spread over the prism surface.
- Look through the eyepiece of the refractometer towards a source of light. Sunlight from a window, or a ceiling light.
- You should see a clear boundary between blue on top and white on bottom.
- If this boundary is not at 35 (using the ppt scale on the right), then use a small screwdriver to adjust the calibration screw on top of the refractometer until the boundary between blue and white is at 35.
- Rinse and clean the prism surface and lid with ultrapure water and then wipe dry.
Sample Analysis
- Add a drop of sample onto the blue prism surface and close the prism lid.
- Look through the eyepiece towards a source of light.
- Read the number at the boundary between blue and white as the value for salinity.
Data Available in LIMS
Expanded SALINTY Report:
| ANALYSIS | TABLE | NAME | ABOUT TEXT |
| SALINITY | SAMPLE | Exp | Exp: expedition number |
| SALINITY | SAMPLE | Site | Site: site number |
| SALINITY | SAMPLE | Hole | Hole: hole number |
| SALINITY | SAMPLE | Core | Core: core number |
| SALINITY | SAMPLE | Type | Type: type indicates the coring tool used to recover the core (typical types are F, H, R, X). |
| SALINITY | SAMPLE | Sect | Sect: section number |
| SALINITY | SAMPLE | A/W | A/W: archive (A) or working (W) section half. |
| SALINITY | SAMPLE | text_id | Text_ID: automatically generated database identifier for a sample, also carried on the printed labels. This identifier is guaranteed to be unique across all samples. |
| SALINITY | SAMPLE | sample_number | Sample Number: automatically generated database identifier for a sample. This is the primary key of the SAMPLE table. |
| SALINITY | SAMPLE | label_id | Label identifier: automatically generated, human readable name for a sample that is printed on labels. This name is not guaranteed unique across all samples. |
| SALINITY | SAMPLE | sample_name | Sample name: short name that may be specified for a sample. You can use an advanced filter to narrow your search by this parameter. |
| SALINITY | SAMPLE | x_sample_state | Sample state: Single-character identifier always set to "W" for samples; standards can vary. |
| SALINITY | SAMPLE | x_project | Project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises |
| SALINITY | SAMPLE | x_capt_loc | Captured location: "captured location," this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2 |
| SALINITY | SAMPLE | location | Location: location that sample was taken; this field is usually null and is unnecessary because any sample captured on the JR has a sample_number ending in 1, and GCR ending in 2 |
| SALINITY | SAMPLE | x_sampling_tool | Sampling tool: sampling tool used to take the sample (e.g., syringe, spatula) |
| SALINITY | SAMPLE | changed_by | Changed by: username of account used to make a change to a sample record |
| SALINITY | SAMPLE | changed_on | Changed on: date/time stamp for change made to a sample record |
| SALINITY | SAMPLE | sample_type | Sample type: type of sample from a predefined list (e.g., HOLE, CORE, LIQ) |
| SALINITY | SAMPLE | x_offset | Offset (m): top offset of sample from top of parent sample, expressed in meters. |
| SALINITY | SAMPLE | x_offset_cm | Offset (cm): top offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset, converted to cm) |
| SALINITY | SAMPLE | x_bottom_offset_cm | Bottom offset (cm): bottom offset of sample from top of parent sample, expressed in centimeters. This is a calculated field (offset + length, converted to cm) |
| SALINITY | SAMPLE | x_diameter | Diameter (cm): diameter of sample, usually applied only to CORE, SECT, SHLF, and WRND samples; however this field is null on both Exp. 390 and 393, so it is no longer populated by Sample Master |
| SALINITY | SAMPLE | x_orig_len | Original length (m): field for the original length of a sample; not always (or reliably) populated |
| SALINITY | SAMPLE | x_length | Length (m): field for the length of a sample [as entered upon creation] |
| SALINITY | SAMPLE | x_length_cm | Length (cm): field for the length of a sample. This is a calculated field (length, converted to cm). |
| SALINITY | SAMPLE | status | Status: single-character code for the current status of a sample (e.g., active, canceled) |
| SALINITY | SAMPLE | old_status | Old status: single-character code for the previous status of a sample; used by the LIME program to restore a canceled sample |
| SALINITY | SAMPLE | original_sample | Original sample: field tying a sample below the CORE level to its parent HOLE sample |
| SALINITY | SAMPLE | parent_sample | Parent sample: the sample from which this sample was taken (e.g., for PWDR samples, this might be a SHLF or possibly another PWDR) |
| SALINITY | SAMPLE | standard | Standard: T/F field to differentiate between samples (standard=F) and QAQC standards (standard=T) |
| SALINITY | SAMPLE | login_by | Login by: username of account used to create the sample (can be the LIMS itself [e.g., SHLFs created when a SECT is created]) |
| SALINITY | SAMPLE | login_date | Login date: creation date of the sample |
| SALINITY | SAMPLE | legacy | Legacy flag: T/F indicator for when a sample is from a previous expedition and is locked/uneditable on this expedition |
| SALINITY | TEST | test changed_on | TEST changed on: date/time stamp for a change to a test record. |
| SALINITY | TEST | test status | TEST status: single-character code for the current status of a test (e.g., active, in process, canceled) |
| SALINITY | TEST | test old_status | TEST old status: single-character code for the previous status of a test; used by the LIME program to restore a canceled test |
| SALINITY | TEST | test test_number | TEST test number: automatically generated database identifier for a test record. This is the primary key of the TEST table. |
| SALINITY | TEST | test date_received | TEST date received: date/time stamp for the creation of the test record. |
| SALINITY | TEST | test instrument | TEST instrument [instrument group]: field that describes the instrument group (most often this applies to loggers with multiple sensors); often obscure (e.g., user_input) |
| SALINITY | TEST | test analysis | TEST analysis: analysis code associated with this test (foreign key to the ANALYSIS table) |
| SALINITY | TEST | test x_project | TEST project: similar in scope to the expedition number, the difference being that the project is the current cruise, whereas expedition could refer to material/results obtained on previous cruises |
| SALINITY | TEST | test sample_number | TEST sample number: the sample_number of the sample to which this test record is attached; a foreign key to the SAMPLE table |
| SALINITY | CALCULATED | Top depth CSF-A (m) | Top depth CSF-A (m): position of observation expressed relative to the top of the hole. |
| SALINITY | CALCULATED | Bottom depth CSF-A (m) | Bottom depth CSF-A (m): position of observation expressed relative to the top of the hole. |
| SALINITY | CALCULATED | Top depth CSF-B (m) | Top depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user. |
| SALINITY | CALCULATED | Bottom depth CSF-B (m) | Bottom depth [other] (m): position of observation expressed relative to the top of the hole. The location is presented in a scale selected by the science party or the report user. |
| SALINITY | RESULT | instrument_used | RESULT instrument used: indication of whether the manual/optical or digital salinometer was used |
| SALINITY | RESULT | salinity | RESULT salinity (unitless): salinity number of the interstitial water sample (roughly parts-per-thousand salinity, but in the unitless PSU scale) |
| SALINITY | RESULT | ssup_asman_id | RESULT spreadsheet uploader ASMAN_ID: serial number for the ASMAN link for the spreadsheet uploader file |
| SALINITY | RESULT | ssup_filename | RESULT spreadsheet uploader filename: file name for the spreadsheet uploader file |
| SALINITY | SAMPLE | sample description | SAMPLE comment: contents of the SAMPLE.description field, usually shown on reports as "Sample comments" |
| SALINITY | TEST | test test_comment | TEST comment: contents of the TEST.comment field, usually shown on reports as "Test comments" |
| SALINITY | RESULT | result comments | RESULT comment: contents of a result parameter with name = "comment," usually shown on reports as "Result comments" |
Archived Versions
Salinity User Guide: 29th September 2022