Closed-Loop Square-Wave Anodic Stripping Voltammetric Analyzer for In Situ Monitoring of Labile Trace Metals in...

Area of Science:

• Marine chemistry
• Analytical chemistry
• Oceanography

Background:

• Deep ocean trace metal quantification is vital for marine biogeochemical cycles.
• Extreme conditions (pressure, temperature, low concentrations, interferences) pose analytical challenges.
• Existing methods struggle with in situ reliability in deep-sea environments.

Purpose of the Study:

• To develop and validate a novel analyzer for reliable in situ trace metal quantification in the deep ocean.
• To overcome the analytical challenges posed by extreme deep-sea conditions.
• To enable quantitative electrochemical observations in extreme marine environments.

Main Methods:

• Development of a closed-loop square-wave anodic stripping voltammetric (SWASV) analyzer.
• Integration of microelectrode-array sensing, environmental regulation, and signal-stability feedback.
• Utilized MEMS-fabricated iridium microelectrode arrays, in situ renewable mercury film, dissolved-oxygen removal, and temperature-normalized signal correction.

Main Results:

• The analyzer successfully reduced temperature-induced signal deviations from over 50% to within ±10-15% under simulated deep-sea conditions.
• Baseline noise and drift were effectively suppressed.
• In situ measurements of Zn(II), Pb(II), and Cu(II) at depths up to 1800 m in the western Pacific showed good agreement (within ±15%) with ICP-MS validation.

Conclusions:

• Closed-loop electrochemical regulation offers a robust solution for quantitative trace-metal measurements in extreme marine environments.
• The developed analyzer enables long-term, unattended, and reliable electrochemical observations in the deep sea.
• This technology advances our ability to understand deep ocean biogeochemical cycles.