Enhancing insight into DOM fate in aquatic systems: Introducing the FLOTATION model

Area of Science:

• Environmental Chemistry
• Aquatic Science
• Water Quality Modeling

Background:

• Traditional water quality models inadequately represent dissolved organic matter (DOM), particularly its bio-refractory fraction.
• Key DOM processes like photodegradation are often omitted from existing water quality models.
• A more comprehensive model is needed to accurately simulate DOM dynamics in aquatic systems.

Purpose of the Study:

• To develop and apply the FLOTATION model for a detailed analysis of DOM sources, distribution, and fate.
• To incorporate biodegradation, photodegradation, and primary production into DOM modeling.
• To assess the impact of these processes on DOM components in the Nanfei River.

Main Methods:

• Developed the FLOTATION (FLuorescent dOm Transport And TransformatION) model.
• Applied the model to the Nanfei River under low flow conditions.
• Calibrated the model using longitudinal measurements of humic-like (C1-C4) and protein-like (C5) DOM components identified via EEM-PARAFAC.

Main Results:

• The FLOTATION model accurately reproduced longitudinal variations of all DOM components.
• Photodegradation significantly reduced humic-like DOM components (C1, C2, C4) by 15-21%.
• Algal primary production contributed 18% to downstream DOM loading, highlighting its role as an autochthonous source.

Conclusions:

• The FLOTATION model provides a more robust framework for understanding DOM fate and transport.
• Photodegradation and primary production are critical processes influencing DOM dynamics in rivers.
• This model enhances the comprehensive assessment of DOM in aquatic environments.