Continuous water monitoring of platinum and carbon electrodes potential for assessing redox potential and biological activity in the intertidal zone.

Continuous monitoring in coastal environments is essential for detecting the outbreak of environmental issues. Potentiometric sensors, which utilize electrodes to detect oxidation-reduction (redox) reactions, offer a valuable approach for such monitoring. In this study, we investigated the applicability of platinum electrode (PtE) and carbon fiber board electrode (CfbE) with distinct response characteristics for redox reaction and biological growth environment monitoring in intertidal environments. The field observation was conducted for 6 months to measure the changes in electrode potentials with the natural phenomenon. PtE and CfbE potentials responded to variations in DO, reflecting the influence of tide fluctuations on the intertidal environment. PtE potential was mainly maintained 0.35 V and detected reductant introduction. CfbE potential varied depending on the development of algae-based biofilms on the electrode surface. The biofilm acted as a direct or indirect electron acceptor at the water layer and the electrode interface, resulting it to have a potential of -0.1-0.4 V. These characteristics demonstrated the capacity of these electrodes to monitor the abiotic state and biological growth conditions in the water layer, enabling the health assesment of the intertidal zone environment. The attachment of sediment particles and the biofilm on the electrode surface had a negligible impact, indicating their durability for long-term monitoring. Therefore, PtE and CfbE application has the potential to reliably assess redox and biological activity in intertidal zones.