title: Spatial and temporal variation in the stable isotope composition (δ18O and δ2H) of rain across the tropical island of Sri Lanka.
abstract: Seasonal and spatial variation in δ18O and δ2H in rainwater was determined in three selected transects across Sri Lanka, the tropical island in the Indian Ocean. Local meteoric water lines (LMWLs) for three distinguished climatic zones; wet, dry and intermediate were constructed. LMWLs show slight variations in their gradients and respective d-excess values, depending on the air moisture origin, circulation and environmental conditions of each climatic zone. The elevation effect and amount effect could be identified but the continental effect is not significantly seen in the isotope composition of rain in the concerned areas. The results reasonably revealed that the distinct rainfall regimes; two monsoonal rains and two convectional (inter-monsoon) rains have characteristic isotopic signatures. Also the impact of (i) terrestrial and oceanic moisture sources, (ii) depression and cyclonic conditions of the Bay of Bengal, and (iii) topography of the country on the variation of the isotopic composition of rain in Sri Lanka could be satisfactorily identified.
authors.affiliation: a Isotope Hydrology Section , Sri Lanka Atomic Energy Board , Orugodawatta , Wellampitiya , Sri Lanka.
authors.forename: E A N V
authors.initials: EANV
authors.lastname: Edirisinghe
authors.affiliation: b Department of Geology, Faculty of Science , University of Peradeniya , Peradeniya , Sri Lanka.
authors.forename: H M T G A
authors.initials: HMTGA
authors.lastname: Pitawala
authors.affiliation: b Department of Geology, Faculty of Science , University of Peradeniya , Peradeniya , Sri Lanka.
authors.forename: H A
authors.initials: HA
authors.lastname: Dharmagunawardhane
authors.affiliation: c Department of Physics, Faculty of Science , University of Peradeniya , Peradeniya , Sri Lanka.
authors.forename: R L
authors.initials: RL
authors.lastname: Wijayawardane
mesh_terms: D003903:Deuterium / Q000032:analysis*; D004784:Environmental Monitoring; D010103:Oxygen Isotopes / Q000032:analysis*; D011891:Rain / Q000737:chemistry*; D012621:Seasons; D013188:Sri Lanka
chemical_list: D010103:Oxygen Isotopes; D003903:Deuterium
keywords: Air moisture; Sri Lanka; deuterium excess; isotope effects; isotope hydrology; rainwater; tropical island