The bulk of seawater is an aqueous solution of inorganic salts and gases. But if it was just that, life as we know it would not exist on Earth. Aside this inorganic material, at least ten thousands of different organic molecules, known as dissolved organic matter (DOM), exist in picomole amounts in each liter of seawater. A delicate balance between photosynthesis and respiration exists on earth, and algal products are available to microbial consumers only as DOM. Most of DOM is quickly turned over by bacteria within hours and days after production. A small fraction of DOM, however, resists microbial degradation. This refractory fraction of DOM has persisted in the ocean for thousands of years and has accumulated to one of the largest pools of reduced carbon on earth’s surface. DOM could provide an important feedback mechanism in the climate system, because minor changes in the DOM pool would considerably impact atmospheric CO2 and the radiation balance on earth. Yet the cycling of DOM in the ocean is not well understood.
Our knowledge of the organic carbon cycle is largely phenomenological and descriptive. Only if we understand the molecular structure of the individual players can we appreciate their functioning, similar to the progress made in medicine, where structure-function relationships led to the development of genomics and proteonomics, making it possible to predict and treat concerns before symptoms appear. Structure-function relationships for DOM and other organic matter pools are required to understand earth’s past and future. Recent progress in analytical chemistry has allowed the characterization of DOM at the molecular level in unprecedented detail, revealing new insights into its source and history.
My research covers four main themes:
1 - Millennium-scale stability of DOM
2 - Molecular interactions between microorganisms
3 - Application of novel concepts in biogeochemical systems
4 - Method development