Indonesia Conference Directory

Abstract. The Ijen volcano was Pleistocene volcano and is one of the strato volcanoes which was active in the middle row of Java Island. This volcano erupts by magmatic and phreatic eruptions. This volcano has the largest natural lake in the world measuring around 960 x 600 m. The morphology of the crater was limited by embankments with heights between 2.145-2386 m. The lowest height of the western embankment was upstream from Banyupait River. The water volume of the crater lake of Ijen volcano is quite large and very acidic. The acidic water from the crater lake flows from upstream Banyupait River to the north to the lower direction of the Asembagus Situbondo area. In this study the methodology of field survey and measurement was used. The field survey was carried out along the flow of Banyupait Asembagus River, which began from the Bantal village to the mouth of the river in the Java Sea.In conducting a field survey pH measurements were also carried out from the river water of the Kali Banyupait. The observations showed that the river water upstream of Banyupait River had a pH of around 2-3, while the more towards the downstream the pH of the river water changed to an increase of around 3-4, because the acidic water of this river experienced dilution from several rivers in its area. Whereas in river estuaries, the river water mixes with the sea, so water has a pH of 4.2. Because river water is acidic (low pH), no biota along the Banyupait river was found. Besides that, the other characteristics of river water are brown. Rocks exposed to the river flow will be reddish in color, experiencing iron oxide. This was due to the interaction process of river acid with rocks. However, the river water was used by residents around the river for agriculture and daily necessities, consequently the health of the population around Bantal village was low.