Methods for Obtaining High Frequency 13CO2 Measurements

The goal for this research project is to understand how plants control water use. This is crucial when accounting for the water availability of a plant and drought analysis. A plants ability to assimilate mass in comparison to how much water it uses is known as water use efficiency (WUE). A current method of determining WUE measures heavy carbon (13C) to light carbon (12C) ratios (δ13C) that come out of a plant in the form of carbon dioxide. However this method doesn't account for some metabolic processes that may affect δ13C. Accurate WUE data is important in understanding local and global carbon cycles and watersheds. Our study differs from other studies on this topic by accounting for all the carbon in a plant by using a hydroponic method I developed to grow the plants. We will use hydroponic plant chamber and controlled air sources to grow Brassica rapa (a small herbaceous plant) and measure δ13C values. This system will also allow us to conduct a complete carbon budget of this plant. This experiment will improve our understanding of mountain front hydrology, as well as how disturbances affect plants that affect water flux. It can also improve integrated modeling of the fate and transport of water.