Dr Ron Smernik

• Research Interests

  Most of my research interests involve organic matter. Brief descriptions of some specific aspects are outlined below. Please contact me if you want to know more about these - or anything else about organic matter.

  Sorption of organic chemicals to organic matter.

  Organic matter is the most important sorbent phase for non-ionic species in soils and sediments. Sorption to organic matter controls the bioavailability, toxicity and transport of small organic molecules such as hydrocarbons and many pesticides. In most studies, only the amount of organic matter is considered, yet it is known that the nature of the organic matter is also critical. We are addressing this issue by developing new methods that can "see" where in the organic matrix small molecules are sorbed. This approach enables us to test competing theories on the nature of sorption sites (e.g. glassy/rubbery organic matter, hole-filling mechanisms and the role of alkyl and aromatic C). Project funding comes from a 5-year ARC Discovery grant, and is being carried out in collaboration with CSIRO.

  The link between chemistry and microbiology in soil carbon cycling.

  Although it is well known that rates of organic matter degradation and C cycling in soils are controlled by both the chemistry of the organic matter and the composition of the microbial degrader community, the details of how they interact are poorly understood. In this project we are applying newly developed techniques from the fields of soil chemistry and microbiology to better understand this interaction. Project funding also comes from a 3-year ARC Discovery grant, and is being carried out in collaboration with CSIRO.

  Quantification and characterization of black carbon (BC) in the environment.

  Black carbon is the residue of incomplete combustion of fossil fuel or vegetation, and includes char and soot. BC is relatively chemically inert in the environment, and this inertness makes it a potentially important carbon sink in both soils and sediments. The trouble is that BC is difficult to quantify – a number of techniques have been developed to do the job, but they give widely varying values, making it virtually impossible to generate reliable estimates of global BC pools, or to understand its movement and fate in the environment. We have developed new NMR-based techniques to measure not only how much BC a sample contains, but also shed light on its composition (BC composition actually varies quite widely). Some of this work is included in the "BC Ring Trial", an international comparison of BC quantification techniques http://www.geo.unizh.ch/phys/bc/ringtrial.html.

  Characterization of organic phosphorus.

  20-80% of phosphorus (P) in soils is present in the form of organic P. Since inorganic P can get locked up in stable forms that remain unavailable to plants for decades to centuries, the organic P pool has come under scrutiny as a potential source of P for plants. Conventional wisdom has it that much of this organic P is there as phytate - a small, stable, phosphorus-rich molecule found in seeds. However, recent results from our labs have cast doubt on this. We are now seeking to better understand the nature of organic P in soils. This work involves collaborators in NSW and Switzerland.

  Chemistry of organic matter in sewage sludge.

  Sewage sludge is a rich source of organic matter and is often used as a soil ameliorant. But what happens to this organic matter once in the soil? We have shown using NMR that the organic matter in sewage sludge has a different chemistry to that found in soil, and are using this to trace the fate of sewage sludge amendments. This work involves collaborators in the UK.

  Development of NMR techniques.

  The research described above utilizes new NMR techniques we have developed specifically for the characterization of organic matter. This is continuing process - each new or improved technique we develop is another tool in the kit-bag.

• Publications

Entry last updated: Wednesday, 21 Nov 2012