Biogeochemistry of mineral-associated organic matter

Typically, 20-90% of the vast pool of soil organic compounds exists as mineral-associated organic matter (MAOM) and these associations strongly influence the biogeochemistry of soil organic matter.

The purpose of current proposal is to investigate physicochemical properties and fungal decomposition of this abundant, composite Earth material.

We will study MAOM formed via the interactions between dissolved organic matter (DOM) and minerals, and relate the physicochemical properties of MAOM to the stability against fungal decomposition.

The overall aims of the project are: 1) To determine how the chemical and colloidal properties of DOM and the mineral surface chemistry control the chemical composition, lateral distribution and adsorption/desorption behavior of MAOM; 2) To determine the extent and mechanisms of fungal decomposition of MAOM during C, N or P acquisition.

These aims will be reached by assessing tightly controlled abiotic and fungal microcosm experiments with a range of spectroscopic and imaging methods.

We will complement these studies with analyses of MAOM formed under field conditions in order to make connections to real soil systems of higher complexity.

The project will focus on processes relevant in boreal forest soils and decomposition mechanisms characteristic of fungi, but the fundamental molecular and mechanistic character of the research will generate knowledge that contributes to a general understanding of the formation and stabilization of MAOM.