Assessment of pollutant exposure and nitrogen enrichment experienced at the University of Michigan Biological Station in 2007

Abstract

The chemical composition of the air is influenced by meteorological conditions, emissions, and climate change. Atmospheric composition can have detrimental impacts on tree physiology that can lower productivity, but can also have positive nutrient enriching impacts that can increase productivity. Hourly ambient values of SO2, NO2, and O3 for Pellston, MI were used to calculate the number of times each pollutant separately and together would exceed critical levels set by the World Health Organization European Air Quality Guidelines (WHO Air Quality, 2000). Hourly ambient values of these pollutants were also converted to weekly and monthly (24 hour day and daylight day) to analyze whether the suite of pollutants of SO2, NO2, and O3 would have a significant influence on the residual variance of NEE and GPP after the primary drivers of photosynthetic photon flux density (PPFD), vapor pressure deficit (VPD), soil moisture, air temperature, and humidity are taken into account. After running the data in the SPSS statistical package, it was found that the suite of pollutants did not cover the residual variability for either NEE or GPP, but that AT1.5(NO2) (among all the pollutants) was found to be significant the greatest number of times out of the 24 trial runs. Out of all the trial runs tested, it was found that the pollutants were significant a greater number of times in monthly, daylight hours, for NEE.