안정동위원소를 이용한 제주삼다수 유역의 지하수 함양 특성 연구

초록

This study evaluated monthly, seasonal and altitudinal changes of oxygen and hydrogen isotope compositions of wetprecipitation samples (n = 238) that were collected for last four years from 7 altitudes (from 265 to 1,500 m above sealevel) in the Jeju Samdasoo watershed at the southeastern part of Jeju island, in order to examine the rechargecharacteristics of groundwater that is pumped out for the production of the Samdasoo drinking mineral water. Precipitationsamples showed a clear seasonal change of O-H isotopic composition as follow, due to the different air masses and relativehumidity: δD =7 .3δ18O +11.3 (R2 = 0.76) in the wet season (June to September), while δD= 7 .9δ18O + 9.5 (R2 = 0.91) inthe dry season (October to May). In contrast, the stable isotope compositions of groundwater were nearly constantthroughout the year and did not show a distinct monthly or seasonal change, implying the well-mixing of infiltrated waterduring and after its recharge. An altitudinal effect of the oxygen isotope compositions of precipitation was also remarkablewith the decrease of –0.19‰ (R2 = 0.91) with the elevation increase by 100 m. Based on the observed altitudinal change,the minimum altitude of groundwater recharge was estimated as 1,200 m above the sea level in the Jeju Samdasoowatershed.

키워드