Digestion diatom using Battarbee and Ruhland methods for Pengilon Lake, Dieng, Wonosobo, Central Java, Indonesia

Abstract

Diatoms have been used as a bioindicator of water quality since 1990s. Digestion methods are a fundamental process prior to paleolimnological analysis with the aim to remove organic material from diatom cells which makes it easier for the identification process. This research objective was to evaluate different methods for digestion diatoms that suitable for samples from tropical sediment, especially from Pengilon Lake Dieng, Central Java, Indonesia. Pengilon Lake was formed by eruption of Mount Prahu with clear water and used as an irrigation source. This research was compared Battarbee and Ruhland methods. In the Battarbee method, the samples were freeze-dried, and approximately 1 gram of each sample was measured and used HCl-H2O2 for extraction of the diatom. In the Ruhland method, the samples were freeze-dried, and approximately 1 gram was digested in 10 ml of concentrated HNO3-H2SO4. Under the Battarbee method, at least 21 diatom species were identified, and under the Ruhland method, 23 diatom species were identified. Ruhland method is less time consuming around 33 hours, where the Battarbee method around 73 hours. From the visibility Battarbee method, striae are clear, but some undigested material disturbing identification process. The different results of diatom caused by the imperfect digestion of the organic material, which is influenced by chemical components for extracts organic. As far as the Ruhland method are an appropriate digestion method in a tropical area such as Pengilon Lake.