Dataset: SOTS Si profile

Name: Programmable Flow Injection (pFI) Silicate Vertical Profile Data from R/V Investigator IN2023_V04 in the Southern Ocean during June 2023 (pFI-SI-LOV project)
Published: 2024-07-08
Keywords: silicate, SOTS, pFI, oceans

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Spatial Extent: N:-46.80044 E:142.35452 S:-46.80094 W:142.35282

Australian Sector of the Southern Ocean

Project:

Collaborative Research: Developing Automated Nutrient and Trace Metal Methodology using Programmable Flow Injection (pFI-SI-LOV)

Principal Investigator:

Maxime Grand (Moss Landing Marine Laboratories, MLML)

Contact:

Maxime Grand (Moss Landing Marine Laboratories, MLML)

BCO-DMO Data Manager:

Sawyer Newman (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2024-07-08

Restricted:

Validated:

Current State:

Preliminary and in progress

Programmable Flow Injection (pFI) Silicate Vertical Profile Data from R/V Investigator IN2023_V04 in the Southern Ocean during June 2023 (pFI-SI-LOV project)

Abstract:

To establish the shipboard capabilities of our newly developed programmable Flow Injection (pFI) silicate analyzer, we collected and analyzed a full-depth vertical profile for silicate (Si) at the Southern Ocean Time Series in the Australian sector of the Southern Ocean in June 2023. For maximum accuracy, the pFI instrument was calibrated using working standards prepared in low nutrient seawater (LNSW, 0-119 umol/L). All 35 individual samples were analyzed in triplicate, the Si(OH)4 data lists the mean of these.

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Methods & Sampling

Unfiltered seawater samples were collected from the Niskin bottles in acid-washed plastic tubes. The stored samples were immediately analyzed for silicate in triplicate using the pFI assay protocol outlined in Hatta et al. (2021). One key modification was adjusting the holding coils’ temperatures to 25ºC instead of the originally specified 50ºC. In tandem with this temperature change, the stop flow time in the flow cell was extended to 60 seconds to ensure the absorbance of the silicomolybdenum blue at 810 and 660 nm product reached a steady state.

We used a miniSIA-2 instrument (miniSIA2, GlobalFIA, Fox Island, USA) equipped with a 8-port LOV unit and a 20 cm flow cell furnished with a Tungsten Halogen light source and UV-VIS spectrophotometer (Ocean Insight, USA) and a 14 position auto sampler (GlobalFIA, USA). The entire system was controlled with FloZF software (v 5.2, GlobalFIA). The system was calibrated using silicate working standards prepared in low nutrient seawater (LNSW, (0-119 µmol L-1 Si)).

Problems/Issues

Quality flags represented in the primary data file 1 = good 2 = bad 3 = below detection limit 9 = not sampled

Data Processing Description

To accommodate the analysis of Si samples from full depth ocean profiles within the constraints of a 20 cm flow cell, a dual measurement wavelength approach was adopted. For low Si samples (< 40 µmol L-1), the difference between the baseline corrected absorbances at 810 nm and the 1050 nm reference was used. For high Si samples (> 40 µmol L-1), a singular, baseline corrected measurement wavelength at 660 nm was employed. Silicate concentrations were calculated using the mean absorbances (660 nm for Si > 40 µmol L-1 and 810-1050 nm for Si < 40 µmol L-1) and the intercept and slope of the corresponding calibrations curves (660 nm calibration curve for Si > 40 µmol L-1 and 810-1050 nm calibration curve for Si < 40 µmol L-1 ).

BCO-DMO Processing

- Units removed from parameter names in primary data file
- Spaces in parameter names replaced with underscores ("_")

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1924539

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
IN2023_V04	INIV	2023-06-05	R/V Investigator		data info

Instruments

Flow Injection Analyzer

Supplied Name: miniSIA-2 (GlobalFIA, Fox Island, USA)

Supplied Description:

Instrument Type

Generic Name: Flow Injection Analyzer

Acronym: FIA

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB36/

Generic Description:

An instrument that performs flow injection analysis. Flow injection analysis (FIA) is an approach to chemical analysis that is accomplished by injecting a plug of sample into a flowing carrier stream. FIA is an automated method in which a sample is injected into a continuous flow of a carrier solution that mixes with other continuously flowing solutions before reaching a detector. Precision is dramatically increased when FIA is used instead of manual injections and as a result very specific FIA systems have been developed for a wide array of analytical techniques.

Spectrophotometer

Supplied Name: UV-VIS spectrophotometer (Ocean Insight, USA)

Supplied Description:

Instrument Type

Generic Name: Spectrophotometer

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB20/

Generic Description:

An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples.

Parameters

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Dataset: SOTS Si profile