Seawater Nitrate Assessment Using a Correction Algorithm of Temperature and Pressure Up to 10000 Meters

Abstract

Nitrate is essential for primary production in aquatic and marine ecosystems. Recent deep-sea research shows that seawater's ultraviolet absorbance is affected by temperature, salinity, and pressure. This study introduces a new method for measuring nitrate in seawater under pressures from 0 to 100 MPa. It uses the orthogonal projection to latent structure (OPLS) algorithm to adjust spectral data for pressure and temperature, followed by Light Gradient Boosting Machine (LightGBM) to create a nitrate calculation model. The results showed that the method achieved high accuracy. It can operate at 100 MPa, equivalent to 10,000 meters deep, making it ideal for deep-sea nitrate measurement.

Keywords: Deep-sea detection, pressure correction algorithm, calculation algorithm, nitrate quantification