A dual channel gas chromatograph for atmospheric analysis of volatile organic compounds including oxygenated and monoterpene compounds

A dual channel gas chromatograph with flame ionisation detectors has been used extensively for analysis of volatile organic compounds in the atmosphere and forms the basis of two monitoring instruments contributing VOC data to the World Meteorological Organisation - Global Atmosphere Watch network. Recent modifications to the methodology have broadened the scope of the instrument; to incorporate measurements of selected monoterpenes, and achieve improved accuracy in the measurement of oxygenated volatile organic compounds. Analysis of selected monoterpenes has been achieved without any significant loss of resolution of the non-methane hydrocarbons or oxygenated compounds. Quantification of 64 different VOCs of varying functionalities are reported with detection limits in the range 1-5 parts per trillion. Here we present a summary of the instrumental and calibration details for the methodology, which continues to be used on many field projects, along with a discussion of the associated measurement uncertainties.     

Determining Relative Contributions of Vegetation and Topography to Burn Severity from LANDSAT Imagery

Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100–1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.     

Climate change, aerobiology, and public health in the Northeast United States

The epidemiological implications with respect to climate change and public health (e.g., shifts in disease vectors) are beginning to be acknowledged. Less recognized however, are the potential links between climate, plant biology and public health. In addition to being affected by climate (e.g., temperature determines plant range), carbon dioxide (CO₂) represents the raw material needed for photosynthesis and its rapid increase in the atmosphere is expected to stimulate plant growth. While there are a number of means by which plant biology intersects with human health (e.g., plant nutrition), one of the most widely recognized is aerobiology; specifically, the ability of plants to both produce pollen and to serve as a substrate for molds/fungi (e.g., sporulation). The current review represents an initial attempt to coalesce what is known regarding the likely impacts of climate/CO₂ on plant pollen/fungal spores and associated allergic disease that are, or could be, specific to the Northeast United States. Although the current results indicate a number of potentially unfavorable effects, we wish to stress that the current data are based on a small number of experiments. Additional data are crucial to both reduce epidemiological uncertainty and to derive a robust set of mitigation / adaptation strategies.     

Using chemometric models to predict the biosorption of low levels of dysprosium by Euglena gracilis

Environmental Science and Pollution Research - The critical rare earth element dysprosium (Dy) is integral for sustainable technologies. What is concerning is that Dy is in imminent short supply...