Journal of Environmental Hydrology
Electronic Journal of the International Association for Environmental Hydrology
JEH Volume 15 (2007), Paper 20 Posted September 12, 2007
SEASONAL EFFECT ON THE ISOTOPIC PATTERN OF RAINWATER IN LEBANON
2Lebanese Atomic Energy Commission, Beirut, Lebanon
Rainwater chemistry and isotopic parameters were studied over a four year period at representative coastal and highland sites in Lebanon. Major inorganic ion composition showed that calcium and sulfate in rainwater had a crustal origin, while potassium, sodium and chlorine had a marine sea spray origin. All rain samples had an average pH varying between 5.6 and 6.8, showing that precipitation tends to be alkaline. Environmental isotopes provide a local meteoric water line in Lebanon that is close to the Mediterranean line, showing that local precipitation is affected by the humid Mediterranean climate. Isotopic characterization of rainwater showed a depletion in both d18O and dD values in highland stations compared to coastal stations. Season, temperature and rainfall amount strongly influence the depletion in isotopic parameters at continental stations. An evaporative enrichment in rainwater occurs during warm months (November) when rain amounts are small. The seasonal effect is pronounced in both coastal and continental sites in December and January. Tritium data of monthly precipitation from all sites within Lebanon show that there are no significant differences in seasonal effect between stations.
Reference: Saad, Z., and V. Kazpard. 2007. Seasonal effect on the isotopic pattern of rainwater in Lebanon. Journal of Environmental Hydrology, Vol. 15, Paper 20.
Lebanese Atomic Energy Commission
PO Box 11-8281
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