Linking Redox Characteristics to Dissolved Organic Matter Derived from Different Biowaste Composts: A Theoretical...

Area of Science:

• Environmental Chemistry
• Soil Science
• Biogeochemistry

Background:

• Compost dissolved organic matter (DOM) is a complex mix of redox-active molecules influencing soil biogeochemical processes.
• The chemical complexity of DOM and its effect on electron accepting capacity (EAC) and electron donating capacity (EDC) are not well understood.
• Predicting DOM environmental behavior and redox properties is hindered by this knowledge gap.

Purpose of the Study:

• To validate the Vienna Soil Organic Matter Modeler 2 (VSOMM2) for compost DOM analysis.
• To develop a molecular modeling approach for assessing redox sites and molecular interactions in compost DOM.
• To elucidate the relationship between molecular structure and the EAC/EDC of compost DOM.

Main Methods:

• Validated the Vienna Soil Organic Matter Modeler 2 (VSOMM2) using FT-ICR MS data for compost DOM.
• Employed molecular modeling with VSOMM2 and Schrödinger software to analyze compost DOM.
• Categorized compost DOM molecules into three groups based on origin and developed 18 molecular models linked to EAC/EDC.

Main Results:

• Identified Ar-OH, quinone, Ar-SH, and Ar-NH2 as key redox sites in compost DOM.
• Proposed noncovalent contacts, H bonds, salt bridges, and aromatic-H bonds as potential electronic transmission pathways.
• Established links between molecular structure and the electron accepting/donating capacities of DOM.

Conclusions:

• This study provides a molecular-level understanding of compost DOM redox properties.
• The findings enable precise regulation of functional molecules within compost DOM.
• Offers standards for matching compost properties to specific ecosystem service requirements.