The distribution of Siombak lake sediments, a tropical tidal lake in Indonesia

Abstract

Siombak Lake is one of Indonesia’s tropical tidal lakes located in Medan City, North Sumatra Province. This lake is very dynamic because the lake water level is fluctuating according to the Belawan waters’ tidal (Malacca Strait). This study aims to determine the distribution of sediments in Siombak Lake. The research was conducted from December 2018 - August 2019. The observation locations were taken at 8 points representing all depth layers. The technique used was the filtering analysis using the wet sieve method with stratified sediment filters in different diameters (4.75 mm, 1.7 mm, 250 μm, 850 μm, 150 μm). The data analyzed were weight percentage, texture type, C-organic, the content of nitrogen and phosphorus. The results of the analysis of sediment samples show that there are 3 sediment textures, namely loam, silt loam, and sandy loam. The C- Organic content in the sediments of Siombak Lake ranges from 1.73 - 5.10% at high tide and 1.91-4.40% at low tide. Nitrogen levels in the sediments range from 0.15 - 2.40% at high tide and 0.14-2.35% at low tide. Meanwhile, phosphorus levels in the sediments range between 5.95 - 19.86 ppm at high tide and 1.27-16.35 ppm at low tide.