Coupling electrochemical and spectroscopic methods for river water dissolved organic matter characterization

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Water Quality Monitoring

Background:

• Dissolved organic matter (DOM) monitoring is crucial for surface water health and pollution detection.
• Conventional spectroscopic methods offer limited insight into DOM's electrochemical behavior.

Purpose of the Study:

• To integrate electrochemical impedance spectroscopy (EIS) with UV-Vis and fluorescence spectroscopy for improved DOM characterization in river water.
• To gain additional insights into DOM's electrochemical properties not detectable by optical techniques alone.

Main Methods:

• Combined physicochemical parameters, EIS, fluorescence indices, and MCR-ALS resolved DOM fractions.
• Applied principal component analysis (PCA) to a merged dataset for pattern identification.
• Utilized excitation-emission matrix (EEM) fluorescence data for DOM fractionation.

Main Results:

• Low-altitude rivers exhibited the highest DOM content, followed by mid-altitude, and then high-altitude rivers.
• Low-frequency EIS regions correlated with higher DOM content; mid- to high-frequency regions correlated with lower DOM.
• Frequency-dependent EIS patterns indicated differences in DOM charge transfer and dielectric behavior.

Conclusions:

• Electrochemical impedance spectroscopy (EIS) provides valuable electrochemical information complementary to optical methods for DOM analysis.
• The integration of EIS offers a more comprehensive understanding of DOM composition and its implications for water quality assessment.
• This approach enhances the ability to characterize DOM in river systems, aiding in ecosystem health evaluation.