Development of an in-situ sensor for autonomous, high-resolution tracing of ammonia levels in marine waters

durch Dr. Niklas Helle (AG Achterberg)

Mittwoch 17.06.2026, 13:15 → 14:30 Europe/Berlin

5-1.213 - PAZIFIK / PACIFIC- Rechte Seite - Großer, unterteilbarer Konferenzraum (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

Abstract
Ammonium is a key component of the marine nitrogen cycle and an important indicator of water quality and ecosystem dynamics. Accurate quantification in marine environments remains challenging due to rapid biological and chemical transformations influenced by temperature, pH, and microbial activity. Conventional sampling followed by laboratory analysis is prone to errors, as ammonium concentrations can change significantly during storage and handling. In addition, variations in salinity and matrix composition further compromise measurement accuracy and precision. Existing in-situ approaches only partially address these limitations. Ion-selective electrodes offer fast response times but suffer from interferences in seawater and limited long-term stability. Flow-based systems using the indophenol blue method are currently the most advanced, providing automation and sensitivity, but they rely on toxic reagents and relatively high consumption of those.
I will present a novel in-situ sensor based on the o-phthalaldehyde (OPA) fluorometric method, show how this chemistry has been optimized and demonstrate its implementation into a miniaturized, flow-based system to enable accurate, high-resolution and environmentally safer ammonium measurements directly in the marine environment.

Meeting-Link
https://geomar.webex.com/geomar/j.php?MTID=m4f250602f223e560bcd3e29bf91b6152

 

abstractsRD2seminar17062026.pdf

RD2seminar_17June2026.pdf