Abstract: Stable isotopes of N ( 15 N/ 14 N) are broadly used in examining the source of nitrate in groundwater due to the difference of 15 N natural abundance of its contamination sources,e. g.,manure,soil and chemical fertilizer. Nevertheless,nitrogen is not a conservative tracer as its value is a function of its source and isotope fractionation by mineralization,adsorption,nitrification and denitrification that may occur during its generation or groundwater transportation. To identify the source of con...