MAGNETIC CHARACTERIZATION AND GEOCHEMICAL TEST (RARE EARTH ELEMENT) AS LITHOGENIC AND ANTHROPOGENIC COMPONENTS INDICATORS IN SEDIMENT CORE LAKE LIMBOTO

• Main Author: Mirrotin, Sundus
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/43901
• Institution: Institut Teknologi Bandung

Lake sediments may provide records of the lake ecosystems and have been used to study natural environmental changes or human-induced impact. Lake Limboto is a tectonic lake located in Gorontalo Province, has 23 inlet rivers and 1 outlet river. Along with the increasing population pressure surrounding the lake, and occupation of lake land for agricultural and plantation activities, the source of sediment to the lake is no longer thought to originate only from natural rock weathering (lithogenic) but can also originate from human activity waste (anthropogenic). This causes sedimentation so fast that Lake Limboto is included in one of the lakes in Indonesia that is experiencing serious degradation problems. This study uses Lake Limboto sediment cores samples taken from 3 points. The method used is a combination of magnetic methods and geochemical methods (rare earth element). The results show that high magnetic susceptibility (?LF), SIRM, and SIRM/?LF values indicate the presence of anthropogenic components. This is supported by the high presence of La, Nd, and Gd concentrations originating from agricultural waste, electronic waste due to dense residential areas, and hospital waste. While low magnetic susceptibility (?LF), SIRM, and SIRM/?LF values indicate the presence of lithogenic components, characterized by the normal Ce, Pr, and Sc concentrations of REE reference values originating from the bedrock which is crossed by river sediments that flow into Lake Limboto. However, the relationship between magnetic parameters does not occur entirely in the measured REE element, especially in surface sediments, due to the complexity of anthropogenic inputs and the need for further analysis to understand the characteristics of REE in aquatic systems.