Dieudonne TUYISABYIMBABAZI, Elisephane IRANKUNDA
Abstract: Nitrous oxide (N2O) is one of the main three greenhouse gases, besides methane and carbon dioxide that are contributing to global warming. N2O levels have risen approximately by 15 % since the preindustrial times reaching 315ppb in 2000. The current estimate of lifetime of N2O is 120 years. N2O is of concern due to its critical contribution to global warming and to ozone layer depletion along with halogen containing compounds. The main objective of this research was to evaluate the seasonal variability of N2O concentration in Rwanda. The N2O data were obtained from Rwanda Climate Observatory by measurement using mid infrared analyser. The study results indicated that the annual N2O average concentration is 329.5 ppb. The short dry season, the long rainy season, the long dry season and the short rainy season had concentrations of 329.79 ppb, 329.08 ppb, 329.30 ppb and 330.15 ppb respectively. The main reason for the disparity in concentration was the rainfall and temperature differences across the seasons, and regional and continental influences, like biomass burning. We suggest that policies be set to counteract the increase in N2O emissions especially from anthropogenic sources in order to reduce the effects of global warming and ozone layer depletion.
Keywords: Nitrous oxide, Greenhouse gas, Global warming, Ozone layer depletion, Seasonal variability