Temporal Variation of Nitrate Concentrations in Karst Spring in the Western Part of the Gunungsewu Karst Area, Java']Java Island, Indonesia

The presence of nitrate in water has become a concern for many environmentalists because it has reduced the quality of water used to meet people's clean water needs. The study of the temporal variation of nitrate in water flow is expected to provide a complete understanding of the influencing factors that need to be managed to control the nitrate concentration in water. This study aims to analyze the temporal variations in the nitrate concentration at the Guntur Spring, one of the springs in the Gunungsewu Karst Area that plays a role in the provision of clean water. The data used in this research include data on nitrate concentration in spring water, rainfall, and spring discharge. Sampling was carried out every two weeks from February 2018 to March 2019 to understand the temporal variation in nitrate concentrations. Discharge and rainfall data were obtained from automatic recording during the same period as water sampling for nitrate analysis. The result shows that the nitrate concentration throughout the year in the Guntur Spring does not exceed the quality standard. The good water quality is caused by the natural filtration process that is still going well due to the low level of karstification that is still dominated by fissure flows. In addition, this research has found that the most influential variation in nitrate concentration in the spring flow at Guntur Spring is the cropping pattern in the area.