PLANT-DERIVED VOLATILE ORGANOSULFUR COMPOUNDS IN THE ENVIRONMENT
In recent years, the biogeochemistry of volatile organosulfur compounds (VOSCs) has been the focus of significant attention because of increased awareness of their contribution to environmental sulfur, and hence their potential to influence global climate.1-3 Thus, several attempts have been made to develop a global sulfur cycle that adequately defines the sources and fates of these sulfur compounds in the environment.4 All of these proposed models require significant quantities of biogenic sulfur to balance the global sulfur cycle.4 An ongoing challenge in the determination of the atmospheric sulfur burden is that information on terrestrial VOSC contributions is extremely limited, and at this time, represents the greatest uncertainty in estimations of total environmental sulfur sources.5 In particular, sulfur gas flux from living vascular plants to the environment is an important but little studied part of the global sulfur cycle.6 Factors contributing to the paucity of information in this area include: (1) limited knowledge of the diversity of sulfur species emitted (beyond the well-known H2S, dimethylsulfide, methylmercaptan, carbon disulfide, and carbonyl sulfide); and (2) the patchiness in time and space of sulfur gas fluxes from terrestrial ecosystems.5 Compounding these challenges is the fact that VOSCs have most often been detected and identified using hybrid gas chromatography techniques under harsh conditions, which leads to artifact formation and incorrect assessment of the profile of VOSCs that are emitted into the environment.
Our work begins to address these issues through pursuit of the following specific aims: (1) Identification of VOSCs emitted by forest and/or agriculturally important plants and optimization of the analytical methods used for their detection by mass spectrometry under “soft” ionization conditions; (2) Identification of the products and kinetics of the reactions of vascular plant-emitted VOSCs with atmospherically relevant radical species; and (3) Design and development of ambient air analysis platforms that interface with mass spectrometers and permits detection of plant-emitted VOSC’s in real time in air. Identification of the molecular profile of plant-emitted biogenic sulfur will facilitate the study of not only the fates of these compounds in the atmosphere, but also the extent to which they may ultimately contribute to the overall atmospheric sulfur burden, and influence pollution, acid rain, and cloud formation, among other phenomena.
1. Lovelock, J. E., Maggs, R. J. & Rasmussen, R. A. (1972). Atmospheric dimethyl sulphide and the natural sulphur cycle. Nature 237, 452-453.
2. Bates, T. S., Charlson, R. J. & Gammon, R. H. (1987). Evidence for the climatic role of marine biogenic sulphur. Nature 329, 319-321.
3. Andreae, M. O. & Crutzen, P. J. (1997). Atmospheric aerosols: Biogeochemical sources and role in atmospheric chemistry. Science 276, 1052-1058.
4. Aneja Viney, P. & Cooper William, J. (1989). Biogenic sulfur emissions. In Biogenic sulfur in the environment, Vol. 393, pp. 2-13. American Chemical Society.
5. Andreae, M. O. & Andreae, T. W. (1988). The cycle of biogenic sulfur compounds over the Amazon basin 1. Dry season. J. Geophys. Res. 93, 1487-1497.
6. Haines, B., Black, M. & Bayer, C. (1989). Sulfur emissions from roots of the rain forest tree Stryphnodendron excelsum. Biogenic Sulfur in the Environment 393, 58-69.
1. BROADER IMPACTS
Identification of the molecular profile of plant-emitted biogenic sulfur will facilitate the study of not only the fates of these compounds in the atmosphere, but also the extent to which they may ultimately contribute to the overall atmospheric sulfur burden, and influence pollution, acid rain, and cloud formation, among other phenomena. The developed analytical tools and data processing software would find broad utility for analyses relevant to a range of other fields including chemistry, biochemistry, forensics chemistry, food sciences, agriculture, and medicine. Additionally, commercially available hardware and software will be developed. The unique collaboration with JEOL USA Inc., a world leader in mass spectrometric, microscopy and NMR analytical instrumentation, dramatically extends the in-house research capabilities of the UAlbany team. The fundamental research being performed by the team at UAlbany (i.e. investigations into the VOSC emission chemistry of vascular plants, and the study of the reactions of these compounds with environmentally relevant free radicals), will occur alongside more applied investigations at JEOL that are associated with extending the application of novel DART mass spectrometry technologies to solve a number of analytical problems in environmental science. Thus, the topics being address in this proposal are shared interests between the JEOL and UAlbany teams, with each bringing complementary skills to bear. The integration of teaching and research between the postdoctoral and graduate student on the one hand, and the JEOL scientists on the other, unimpeded by departmental or administrative boundaries, will cultivate a cultural shift in research-based instruction. The trainees will gain a breadth of skills, strengths, and understanding to work in an interdisciplinary team environment while being grounded with depth of knowledge in a major field. At the same time, the training will provide scientific and professional preparation for the student and the postdoctoral associate interested in pursuing either an academic or non-academic career. Additionally, the experience will provide a breeding ground for exploration and application of novel experimental approaches to resolve problems. It is anticipated that the UAlbany-JEOL collaboration will produce highly competent and adaptive doctoral scientists, with strong marketable skills.