To cite this article: Yaccob, N. S. et al. (2018). Application of nitrate stable isotopes, δ15N-NO3– and δ18O-NO3–, in Bukit Merah Reservoir, Malaysia. J. Phys. Sci., 29(Supp. 3), 1–6, https://doi.org/10.21315/jps2018.29.s3.1
Identifying nitrate sources in Bukit Merah Reservoir (BMR), Perak, Malaysia is important in order to understand the productivity of the ecosystem. For the first time, the dual stable isotopes of nitrate, δ15N-NO3– and δ18O-NO3–, were applied to assess its potential use to trace the sources of nitrate in surface water of BMR. Water samples were collected in the months of August 2016, December 2016, March 2017 and October 2017 from 10 sites within Kurau River Basin covering the upper stream, tributaries and reservoir. Water samples were analysed using the bacterial denitrification method. The variation of nitrate isotopes ranged from +0.4‰ to +14.91‰ for δ15N-NO3– and –0.01‰ to +39.4‰ for δ18O-NO3–, respectively. Overall, based on the crossplots between δ15N-NO3– and δ18O-NO3–, majority of the δ18O-NO3– in the samples reflects atmospheric deposition whereas δ15N-NO3– indicates sources from both ammonium fertiliser and soil nitrogen, and a minor contribution of sewage and manure in BMR water catchment.