Of special interest to me is the study of trace metals over remote areas of the open ocean. Continentally derived material in the form of dust is subjected to in-cloud processing, similar to weathering of rocks, whereby trace elements are released into the aqueous phase of the particle. Speciation of these elements, especially that of iron, may determine the selective uptake by marine organisms which in turn play an important role in the biogeochemical cycling of major elements and can this affect global climate. However, the detailed mechanisms that control iron speciation in the marine atmosphere remain largely unknown.
Our approach is based on the interpretation of reliable field and laboratory observations. Students participate in month-long research cruises (picture 1 for collector and 2 for lab on a cruise Sept. 2003 over the North Pacific) with scientists from many parts of the world and from a range of different disciplines. Laboratory analyses include Liquid Wave Core Capillary (LWCC) spectrometry, Ion Chromatography (IC), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), and Stable Isotope Ratio Mass Spectrometry (SIRMS). This field data is then interpreted in conjunction with results obtained from photochemical simulation experiments in the laboratory (schematic of photochemical setup).
Funding for this research comes from NSF (Advance Fellows Award 2002-2006; Atmospheres, 2009 - 2011)
2. Ultra Fine Particulate (UFP) Matter and Health Effects
Atmospheric ultrafine particulates from automotive emissions and other human activities have recently been recognized as a significant global health hazard. These ubiquitous nanometer sized pollutants, once inhaled, penetrate cellular membranes and disrupt major metabolic processes that lead ultimately to cell death. In collaboration with CWU colleague Carin Thomas (biochemist) we investigate the presence of surface transition metals and polycyclic aromatic hydrocarbons (PAHs) on UFPs and correlating these to possible toxicological mechanisms.
We collect UFPs in urban and rural areas of Washington State and analyze them for surface iron speciation and PAHs using LWCC (see above), X-ray Photoelectron Spectroscopy (XPS), and Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS). Simultaneously, their toxicological effects are tested in vitro on beef heart mitochondria.
This project was funded by NIH for three years (2005-2008) and work has continued in a somewhat different direction.
3. Long-term Study of Precipitation and High Elevation Lakes Chemistry in Mt. Rainier National Park
The impact of anthropogenic pollutants in sensitive high elevation locations in Mt Rainier National Park has been studied in precipitation and lake water samples since 1989. The main focus lies in identifying trends as a consequence of increasing population density and overall climate change. Weekly precipitation samples, and lake water samples collected during the summer are analyzed for major anions, cations, pH and conductivity. The project is extremely amenable for undergraduate student involvement as they are directly exposed to the complete process from data collection, to sample preparation and analysis, data manipulation and interpretation, and reporting. Students gain valuable experience on a series of analytical instrumentation and learn how to process raw data to obtain a statistically interpretable data set.
