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

Unfiltered seawater samples from the RV Investigator underway lab were aspirated using an auxiliary diaphragm pump (KNF, USA) into a 3 mL sample loop every 15-30 min during the deployment. The stored samples were immediately analyzed for silicate in duplicate 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 660 nm product reached a steady state.