Löhr's Ph.D. study was part of a larger project onthe Ijen Crater Lake on East Java, Indonesia. This crater lake is thelargest collection of volcanic water in the world and is extremelyacidic (pH 0.1). The acidic water slowly seeps away, and despitedilution by two tributaries in the area the pH of the river waterremains very low. This water is used for agricultural and householdpurposes, which sometimes leads to the rice harvests failing. The veryhigh aluminium content of the water – associated with the acidity –also plays an important role in this. Other elements such as fluorine,in the form of fluoride, form a direct threat for public health. Thelevels are not only alarmingly high in the river water but also in thegroundwater and drinking water wells.
Within the large project scientists studied the geochemical andhydrological processes as well as the health risks. Ansje Löhrinvestigated the ecological effects of the acidic water. As well ashaving a harmful effect on the well-being of the local population, itadversely affects the biodiversity.
Löhr sampled the water atvarious locations. She observed that the neutral river water containednormal aquatic fauna, but that only mosquito larvae could survive theextremely acidic water. The diversity of microorganisms and algae wasalso very low. The inhibited breakdown of organic material was anotherecological effect measured. Löhr established this using packscontaining jati and bamboo leaves, which she suspended in the river atvarious locations. She determined the loss dry matter over a period ofseveral months.
According to Löhr, one possible solution for the acidificationproblem is simply to prevent the crater water from mixing with bothneutral rivers. She believes that this could be realised by channellingthe flow of acidic water from the crater into the sea, which with itsenormous water surface would not suffer any detrimental effects due tothis small quantity of acidic water. Löhr wants to hold discussionswith local authorities, other researchers and companies in order toarrange such a diversion or another solution. The biologist recentlyreceived a dissemination grant from NWO-WOTRO to support this.
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