Real-Time Underway Mapping of Nutrient Concentrations of Surface Seawater Using an Autonomous Flow Analyzer

Area of Science:

• Environmental Chemistry
• Oceanography
• Analytical Chemistry

Background:

• Traditional nutrient analysis in dynamic aquatic ecosystems is time-consuming and labor-intensive.
• Simultaneous underway analysis of multiple key nutrients in seawater presents technical challenges.
• Existing techniques often lack portability and autonomous data processing capabilities.

Purpose of the Study:

• To develop and validate a state-of-the-art autonomous portable analyzer for shipboard, underway nutrient analysis.
• To enable simultaneous measurement of five key nutrients (ammonium, nitrite, nitrate, phosphate, silicate) across varied salinities.
• To create a user-friendly system with automated calibration and sample handling for complex environments.

Main Methods:

• Design of compact hardware suitable for shipboard deployment with minimal maintenance.
• Development of novel LabVIEW-based software for automated calibration, autodilution, and multiparameter analysis.
• Optimization of chemical reactions and workflow for high-frequency nutrient determination.

Main Results:

• The analyzer demonstrated low detection limits, a wide linear range with automated dilution, and high precision (RSD < 2%).
• It offers superior portability and reduced reagent consumption compared to other flow-based techniques.
• Successful real-time application in the Jiulong River Estuary-Xiamen Bay confirmed excellent on-site accuracy and applicability.

Conclusions:

• The developed analyzer effectively addresses limitations in underway nutrient analysis for complex aquatic systems.
• Its portability, autonomy, and broad salinity range make it ideal for chemical mapping in dynamic environments.
• Real-time nutrient and salinity data revealed distinct patterns in estuarine and coastal areas, highlighting the analyzer's utility.