Studi Kualitas Air pada Inlet Danau Lau Kawar, Pasca Erupsi Gunung Sinabung di Kecamatan Naman Teran, Kabupaten Karo, Provinsi Sumatera Utara dengan Menggunakan Metode Indeks Pencemaran (IP)

Abstract

The condition of water quality is reflected by the concentration values of several water quality parameters, both physically, chemically and biologically, which are indispensable in designing the management and control of water pollution. One area that is suitable to know the water quality is in Karo district. Activities from the community and the eruption of Mount Sinabung are thought to have reduced water quality at the inlet and lake waters in Karo Regency, namely Lake Lau Kawar. Lau Kawar Lake is located in Kuta Gugung Village, Naman Teran District, Karo Regency which is located at the foot of Mount Sinabung. The inlet of Lake Lau Kawar comes from a spring at the foot of Deleng Lancuk. Mount Sinabung experienced relatively high eruptive activity, erupting 213 times in the period July 2020 to July 2021. The research method used was purposive sampling by determining five sampling points. The physical and chemical parameters of the water at the inlet measured include pH, TDS, BOD, COD, Pb, Mn, Cu, Cl, NH3-N, SO4, and the biological parameter, namely Total coliform. The determination of the water quality status at Inlet the Lau Kawar Lake using the Pollution Index method is in accordance with the Minister of Environment Regulation Number 115 of 2003. Based on the results of laboratory tests, the concentration of pollutant parameters shows that it is still in accordance with the required quality standards according to Government Regulation Number 22 of 2021. In determining the quality status, the Pollution Index method is carried out for all sample points, and the average result for the water at Inlet the Lau Kawar Lake is that it meets the quality standard (score 0 IP 1). Additional tests were carried out for the dominant content of volcanic ash, namely Silicon Dioxide (SiO2) and Aluminum, the results were 33.75 mg/L for SiO2, and 0.00 mg/L for Aluminum where these concentrations have not polluted the water at the Inlet Lake significantly. The effect of the eruption of Mount Sinabung on water quality at Inlet, the Lau Kawar Lakebased on the parameter test results, indicated that it had an effect on water quality at the Lau Kawar Lake Inlet. However, based on the results of the analysis of these parameters, it shows that they are still below the required Quality Standards in accordance with the Government Regulation of the Republic of Indonesia Number 22 of 2021. The parameters of Silicon dioxide (SiO2) and Aluminum which are the parameters with the highest composition contained in the ash of the eruption of Mount Sinabung do not cause the impact of high pollution on water at Inlet the Lau Kawar Lake. The content of silicon dioxide (SiO2) in water Inlet Lake Lau Kawar is 33.75 mg / L which is still below the quality standard in water according to W. Stumm and Morgan JJ (1970) of 120 mg / L and the content of aluminum in water Inlet Lake Lau Kawar is 0.00 mg/L. so that the water at Inlet the Lau Kawar Lake can be said to be not significantly affected by the eruptive activity of Mount Sinabung.