과거 제주도의 주요 수자원이었던 용천수의 수질은 최근 각종 개발사업과 잠재오염원의 증가로 오염이 심화되고 있다. 이에 본 연구는 1999년부터 2020년까지 용천수의 장기간 수질 변동특성을 파악하였다. 이온 분석결과, 고도가 낮아지면서 용천수 내 NO3-N과 Cl-이 증가하여 인위적 오염원과 해수의 영향을 받는 것으로 나타났다. 지난 22년간 NO3-N 농도는 남부지역에서 감소하는 경향이 나타나는 반면, 서부지역에서는 지속적으로높게 유지되었다. 요인분석 결과, 용천수 수질에 영향을 주는 요인은 해수(요인 1)와 인위적 오염원(요인 2)으로, 요인 2의 점수는 동부와 서부유역에서 증가 양상으로 나타남에 따라 이온 분석보다 뚜렷한 수질 변화 경향을 얻을 수 있었다. 용천수 및 반경 1 km 이내 지하수의 평균 NO3-N 농도를 비교한 결과 용천수의 NO3-N 농도가 지하수에 비해 1999년에 1.4배, 2010년에 2.3배, 2014년에 0.9배, 2020년에 4.6배 높았다. 이에 따라, 지하수까지 오염이 확산되기 전에 용천수 수질 보호를 위해 토지 이용 및 오염원 관리, 지속적인 용천수 수질 모니터링이 필요하다고 판단된다.
Spring water, what used to be the most important water resource in Jeju Island has been polluted by industrial developments and the increase in anthropogenic activities. Therefore, this study aimed to understand characteristic changes in the spring water quality from 1999 to 2020. During those time the concentration of NO3-N was shown the highest in the western basin. The NO3-N levels in the southern basin were decreased over time due to reduction of the fertilizer uses resulted in a decrease in the agricultural area. The Cl- concentration was high in the eastern and the western basins where the basal groundwater is present. As a result of the factor analysis, two factors were classified into the effect of seawater (factor 1) and anthropogenic pollution (factor 2). Factor 1 scores in the eastern basin and factor 2 scores in the western basins were higher than those in other basins, which was similar to the results of NO3-N and Cl- analysis. However factor analysis has an advantage as quantifying 67.3 ~ 73.7% of the samples were affected by seawater and it is showing a clearer trend than the interpretation using the NO3-N concentration only. By comparing the water quality of spring water and groundwater within a radius 1 km of the spring, the average NO3-N concentration in spring water was higher than that its concentration in groundwater (1.4 times in 1999, 2.3 times in 2010, 0.9 times in 2014 and 4.6 times in 2020). It implies that the spring water responds relatively more sensitive to changes in the surface environment than groundwater.
Accordingly, it is necessary to preserve the spring water through managing the land use and the pollution source as well as by monitoring the spring water quality continuously before the contamination spreads to the groundwater.