Studi Kualitas Air Danau Lau Kawar, Pasca Erupsi Gunung Sinabung di Kecamatan Naman Teran, Kabupaten Karo, Provinsi Sumatera Utara

Abstract

Lau Kawar Lake is located at the foot of Mount Sinabung which in recent years has experienced relatively high eruptive activity, namely 213 eruptions in the period July 2020 to July 2021, of which 27 eruptions emptied into Lake Lau Kawar. Determination of the quality status of the waters of Lau Kawar Lake is needed to determine its impact on the environment, using the Pollution Index method and the STORET method under the Regulation of the Minister of the Environment Number 115 of 2003. The pollutant parameters tested in this study were pH, Total Suspended Solid (TSS), Lead (Pb), Manganese (Mn), Copper (Cu), Chlorine (Cl), Sulfate (SO4), Ammonia (NH3), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Silicon Dioxide (SiO2 ), Aluminum Oxide (Al2O3), Iron (Fe), and Total Coliform with ten sample points are taken randomly. This shows that it is still following the required Quality Standards according to Government Regulation no. 22 of 2021. Except for the concentration of Iron (Fe) in the range of 0.99 mg/L to 3.49 mg/L which exceeds the standard. In determining the quality status, the Pollution Index method is used for all sample points, and the average result for the waters of Lake Lau Kawar is Lightly Polluted (score 1 IP 5). Meanwhile, the quality status using the STORET method was carried out with a variety of sample points where the existing quality status of Lake Lau Kawar waters was obtained with the predicate Good (score -1 to -10). Both quality statuses are influenced by the pollutant parameters of iron (Fe) which are above the quality standard according to regulations. The effect of Mount Sinabung eruption activity on the water quality of Lake Lau Kawar when sampling did not cause a significant pollution impact due to volcanic ash pollutant, seen from the results of the analysis carried out by the Quality Standards. The results of the descriptive analysis of the direction of the eruption wind towards Lake Lau Kawar are relatively indirect, namely east, southeast and south compared to the opposite direction, where the ratio of the direction of the eruption wind towards the lake in the opposite direction is 1: 8.

Danau Lau Kawar terletak di kawasan kaki Gunung Sinabung yang beberapa tahun kebelakang mengalami aktivitas erupsi yang relatif tinggi, sebanyak 213 kali erupsi pada periode juli 2020 hingga juli 2021 di kmana 27 kali erupsi mengarah ke Danau Lau Kawar. Penentuan status mutu perairan Danau Lau Kawar diperlukan untuk mengetahui dampaknya kepada lingkungan, dengan menggunakan metode Indeks Pencemaran dan metode STORET sesuai dengan Peraturan Menteri Lingkungan Hidup Nomor 115 Tahun 2003. Parameter pencemar yang diuji pada penelitian ini adalah pH, Total Suspended Solid (TSS), Timbal (Pb), Mangan (Mn), Tembaga (Cu), Klor (Cl), Sulfat (SO4), Amonia (NH3), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Silikon Dioksida (SiO2), Aluminium Oksida (Al2O3), Besi (Fe), dan Total Coliform dengan sepuluh titik sampel diambil secara acak. Menunjukkan masih sesuai dengan Standar Baku Mutu yang dipersyaratkan sesuai Peraturan Pemerintah No. 22 Tahun 2021. Kecuali konsentrasi Besi (Fe) dengan kisaran 0,99 mg/L hingga 3,49 mg/L melebihi baku. Dalam menentukan status mutu dengan metode Indeks Pencemaran dilakukan pada untuk semua titik sampel, dan hasil rata-rata untuk perairan Danau Lau Kawar adalah Tercemar Ringan (skor 1 ≤ IP ≤ 5). Sedangkan status mutu dengan metode STORET dilakukan dengan variasi titik sampel di mana didapatkan status mutu eksisting perairan Danau Lau Kawar dengan predikat Baik (skor -1 sampai -10). Kedua status mutu ini dipengaruhi oleh parameter pencemar besi (Fe) yang berada di atas baku mutu menurut peraturan. Pengaruh aktivitas erupsi Gunung Sinabung dengan kualitas perairan Danau Lau Kawar saat pengambilan sampel tidak menimbulkan dampak pencemaran yang cukup signifikani akibat polutan abu vulkanik, terlihat dari hasil analisis yang dilakukan menunjukkan sesuai Baku Mutu. Hasil analisis diskriptif dari arah angin erupsi kearah Danau Lau Kawar relatif tidak secara langsung yaitu berarah timur, tenggara dan selatan dibandingkan kearah sebaliknya, di mana perbandingan arah angin erupsi ke arah danau dengan arah sebaliknya adalah 1 : 8.