STABLE ISOTOPIC COMPOSITION OF METEORIC WATER WITHIN CENTRAL OHIO

The Global Meteoric Water for the stable isotopic composition of precipitation has been used to interpret both hydrological and climatological processes. The Global Meteoric Water Line equation is δD = 8δ¹⁸O + 10, where δD is the variation in stable hydrogen isotopes and δ¹⁸O is the variation in stable oxygen isotopes of precipitation. Variations from this equation in a local meteoric water line (LMWL) can provide information on the environments in which the “local” precipitation was formed and the climatic processes taking place. Deuterium excess is defined as d= δD - 8δ¹⁸O and can be used to understand the vapor source region of precipitation and the amount of recycled precipitation. The purpose of this study was to add to the previous work on the stable isotopic composition of precipitation within Central Ohio. A LMWL was created for Central Ohio using 227 precipitation samples from May 2010 through January 2015. Precipitation samples were collected at two locations in Franklin County, Ohio. The LMWL was determined to be y = 7.95x + 9.54 (R² = 0.9774). Seasonal variation was observed with average winter values of -9.7‰ and -67‰ for δ¹⁸O and δD, respectively, and average summer values of -5.1‰ for δ¹⁸O and -32‰ for δD. D-excess increased with amount of precipitation per year, with an average d-excess of 15‰ when average precipitation per event was 0.98cm and 10‰ when average precipitation per rainfall was 0.45cm. The LMWL intercept of 9.54 indicates that the moisture originated from a humid environment. The seasonal isotope variation is likely caused by seasonal temperature changes. D-excess likely increased with amount of precipitation per event. These observations will be examined in more detail in this presentation.