An exploration of natural mineral nanopores and their potential for interaction with natural dissolved organic matter
Although subsurface microbes are physiologically able to decompose most natural and contaminant organic matter, some fraction of soil and sediment organic matter is preserved over millions of years. It is likely that organic matter is protected from microbial degradation through some type of interaction with mineral surfaces. However, the mechanism responsible for this protection is not known. Recently, it has been proposed that organic matter is protected by occlusion within mineral nanopores (pores 2-50 nm) that are smaller than both the microbes themselves, and the enzymes they exude to breakdown organic molecules. Previous research by the PI using synthetic minerals has shown that a variety of small organic compounds can be strongly sorbed to the internal surfaces of nanopores and that larger organic compounds such as enzymes are excluded from the pores. Although the feasibility of the so-called ‘nanopore protection hypothesis’ was demonstrated, the ‘real-world’ importance of mineral nanopores in organic matter preservation is still unknown.
Here, an investigation of the importance of mineral nanopores to the cycling of organic matter in soils, sediments and groundwater environments is proposed. First, evidence for the widespread natural occurrence of mineral nanopores in these environments will be gathered. Second, experiments will be carried out to show that organic compounds can be sorbed within these natural nanopores. Further, by defining the type of organic compounds (size and chemical character) that can be adsorbed in different types of mineral nanopores (size and chemical character), one can predict the environmental effects of mineral nanopores on organic matter cycling.
These experiments will serve as a ‘proof of concept’ from which to design further explorations (grant proposals) of natural nanoporous materials and their environmental effects. This research is interdisciplinary and of a fundamental nature. Important implications and applications of this research can be found in widely ranging fields such as global carbon cycling and climate change, microbial ecology, petroleum geochemistry, soil science and agriculture, and contaminant remediation.
The University of Florida, as well as the National Science Foundation, has identified nanoscale science and engineering as a research focus area. Requests for proposals on the subjects of nanoscale processes in the environmental and nanogeoscience have been made and will continue to be made in the future. But while some are beginning to look at the importance of nanoparticles in the environment, the presence of nanopores and the influence of nanoscale processes in nanopores is a neglected area of study though its importance may be great.