Environmental assessment by lithogenic and anthropogenic analysis on surface sediment from Lake Cisanti (KM 0 Citarum River)

KARTIKA HAJAR KIRANA; LUH AYU EKA SAFITRI SEPTIANA; DINI FITRIANI; ELEONORA AGUSTINE; EDDY SUPRIYANA; YUDI ROSANDI; MARCOS A.E. CHAPARRO; SATRIA BIJAKSANA; SUDARNINGSIH

Nusa Dua Bali

Congreso; 2nd International Congress on Earth Sciences in SE Asia; 2019

Universitas Padjadjaran and Universiti Brunei Darussalam

Lake Cisanti as the upstream of the Citarum River is located in Tarumajaya Village, Kertasari District, Bandung Regency. This lake is a place where seven springs flow through the Citarum River. Identification of environmental conditions in this lake and surrounding is very important because the upstream of the Citarum River is a water source that is widely used by the community. The aim of this research is to identify and determine the magnetic mineralogy of sediment from Lake Cisanti as an initial stage of magnetic monitoring of river pollution. Surface sediment samples were taken in springs, lakeside, and in the middle of the lake. These samples were measured determining magnetic hysteresis parameters, low frequency magnetic susceptibility (χLF), high frequency magnetic susceptibility (χHF), and the absolute mass specific frequency-dependent susceptibility (χFD). After that, a magnetic mineral extraction was carried out for X-ray diffraction (XRD) and microscopy (SEM-EDS) analyses. Results of magnetic hysteresis parameter showed that minerals of surface sediment samples in Lake Cisanti are ferrimagnetic. It also confirmed by results of XRD diffraction pattern, which show the large amount of magnetite minerals in extracts. Furthermore, these surface sediments are classified as ferromagnetic with an average χLF value of 393.8 x 10-8 m3/kg. Values of χFD and its correlation with χLF indicate that samples contain superparamagnetic grains, being the dominant magnetic minerals that are mostly sourced from lithogenic material. The source of abundance of magnetic minerals in Lake Cisanti not only comes from lithogenic, but also from anthropogenic sources indicated by a negative correlation between χLF and χFD. The analysis by SEM-EDS shows that extracts contain magnetites that have changed the shape from octahedral crystal to spherule, although there are still many magnetite minerals in octahedral shaped.