The Emergence of Extracellular Electron Mediating Functionality in Rice Straw-Artificial Soil Mixture during...

Area of Science:

• Environmental Science
• Soil Science
• Biogeochemistry

Background:

• Humic substances are vital in environmental processes.
• Extracellular electron mediating (EEM) functionality is key to humic substance activity.
• The origin of EEM functionality and redox centers remains unclear.

Purpose of the Study:

• To investigate the origin of EEM functionality in humic substances.
• To identify the redox-active centers responsible for EEM functionality.
• To understand the dynamic changes in EEM functionality during organic matter humification.

Main Methods:

• Humification of rice straw in artificial soil over one year.
• Assessing EEM functionality using pentachlorophenol dechlorination activity.
• Chemical and electrochemical characterizations (e.g., quinone structures, aromaticity, capacitance).

Main Results:

• EEM functionality emerged after one month of humification and was maintained for one year.
• Functionality correlated with rice straw degradation, quinone formation, decreased aromaticity, and increased nitrogenous/aliphatic structures.
• Specific electric capacitance increased during humification.

Conclusions:

• Quinone structures are suggested as potential redox-active centers for EEM functionality.
• Humification dynamically alters EEM functionality and its underlying chemical properties.
• Findings offer insights into the development of EEM functionality in natural organic matter.