Dian Fiantis

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The Krakatau volcano erupted in 1883 and created a unique ecosystem where the surrounding islands were completely sterilised. While volcanic activity and plant succession have been extensively studied in the Krakatau islands, the soils received less attention. As the age of the parent material is known precisely, and the islands are isolated, soils of Krakatau islands could provide insights on the first stages of weathering in tropical volcanic regions. This study aims to characterize soils from the Krakatau islands. In 2015, ten sampling sites were selected from Mt. Anak Krakatau, Rakata, Panjang, and Sebesi islands, all making part of the Krakatau island complex. Field morphology was observed from representative profiles on each island. Soil samples were collected and analysed for physical and chemical properties. The geochemical analysis was carried out using the X-ray fluorescence (XRF). Linear discriminant analysis was used to separate materials from the four islands based on their chemical and geochemical concentrations. While the four islands were nearby and influenced by the 1883 eruption of Mt. Krakatau, the analysis showed that the chemical and geochemical characteristics of volcanic ash for each island are distinct. Discriminant analysis of chemical and geochemical properties differentiated soils of Anak Krakatau as the youngest ones, and soils of Sebesi are the most developed ones. The following sequence of the soil weathering degree was established: Sebesi > Rakata > Panjang > Anak Krakatau.