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(70-40) Ecotoxicity of volcanogenic heavy metals in the Kawah Ijen ecosystem, East-Java, Indonesia. Löhr, A.J.*,1, van Gestel, C.A.M.1, van Straalen, N.M.1, Widianarko, B.2, 1 Vrije Universiteit, Institute of Ecological Science, Amsterdam, The Netherlands2 Universitas Katolik Soegijapranata, Semarang, Indonesia ABSTRACT- River systems in the Kawah Ijen region in East Java offer a unique opportunity to study ecological effects of high dissolved metal concentrations under extremely low pH conditions. The Banyupahit is a 50 km long extremely acidic river (pH 0.7- 3.5) originating from the Kawah Ijen crater lake (pH <0.1). The river has an increasing pH and decrease of volcanogenic pollutants. Dilution of the acid river water can be attributed to two tributaries; there is an increase of approximately pH 0.7 to pH 2.3 through dilution with river water originating from the Kali Sat and an increase of approximately pH 2.3 to pH 3.0 originating from the Kali Sengon. In the coastal area the water is used for irrigation. Main question of this study is to what degree pH is a limiting factor for the occurrence of certain macro-invertebrate species. Therefore aquatic macro-invertebrates were sampled to define communities in both the extremely acidic Banyupahit and the neutral river Kali Sengon. Only few macro-invertebrates species, mainly chironomids, in very low abundances were found along the entire stretch of the Banyupahit river. This observation can probably not be attributed to a low pH only. It is therefore suspected that high contents of metals or other dissolved chemicals such as nitrate, phosphate and sulphate play an important role in limiting the development of aquatic animal life. To further investigate this, indicator organisms are selected for TIE type toxicity studies in the laboratory. Information on the internal critical concentrations will be used to estimate ecological effects of metal toxicity to indicator species. Key words: metals, pH, macroinvertebrates, TIE |
