Improved Understanding of Dissolved Organic Matter Processing in Freshwater Using Complementary Experimental and...

Area of Science:

• Environmental Chemistry
• Aquatic Chemistry
• Analytical Chemistry

Background:

• Dissolved organic matter (DOM) is crucial in aquatic ecosystems but complicates drinking water production due to its complex molecular nature.
• Understanding DOM's reactivity is vital for managing water quality and treatment processes.
• Current knowledge of DOM transformations in natural environments is limited by its molecular complexity.

Purpose of the Study:

• To disentangle the reactivity of dissolved organic matter (DOM) based on photochemical and microbial transformations.
• To establish a classification system for DOM reactivity linked to molecular properties.
• To identify DOM precursors for disinfection byproducts in drinking water.

Main Methods:

• Utilized Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to analyze DOM molecular formulas.
• Correlated FT-ICR-MS data with chlorophyll a and solar irradiation to define DOM reactivity classes.
• Employed a random forest model to predict DOM reactivity based on molecular features.

Main Results:

• Defined 9 reactivity classes for 1277 common molecular formulas based on environmental data.
• Attributed DOM processing in a drinking water reservoir to photochemical transformations in summer.
• Distinguished microbial DOM alterations and identified photoproducts and microbial products as potential disinfection byproduct precursors.

Conclusions:

• Developed an expandable classification approach to integrate DOM reactivity with molecular properties.
• Demonstrated the link between DOM molecular features, environmental transformations, and water quality implications.
• Provided insights into DOM behavior in aquatic systems for improved water treatment strategies.