Mercury (Hg) contamination in Manado Bay, North Sulawesi, Indonesia

Abstract

Title (Bahasa Indonesia):Kontaminasi merkuri (Hg) di Teluk Manado, Sulawesi Utara, IndonesiaArtisanal gold minings, which are situated in the highlands of the northern part of Sulawesi Island,use mercury (Hg) to extract gold and dischargetheirs tailings into rivers; one of the rivers(Bailang River) is connected to Manado Bay. This could cause Hg contamination into the bay. This study aimed to assess the contamination of Hg in the aquatic ecosystem of the bay. For the assessment, the bay was divided into 2 parts, namely the North and the South, and the contamination was assessed by measuring the total Hg concentration in sediments and fishes. Determination of Hg concentration refers to the Indonesian National Standard (SNI) 01-2896-1992 and Guidance of Balai Riset dan Standarisasi Industri Manado. The results showed that the range of Hg concentrations in fish varied by species; in the northern part of the bay: Holocentridae (0.1144-0.1151 ppm), Siganidae (0.0020-0.0034 ppm), Apogonidae (0.0461-0.050 ppm), and Nemipterus (0.0142-0.0144 ppm ). While in the southern part of the bay: Holocentridae (0.1090-0.1104 ppm), Siganidae (0.160-0.164 ppm), Apogonidae (0.1280-0.1291 ppm), Nemipterus (0.0522-0.0530 ppm) , and Priacanthus sp. (0.0194-0.0210 ppm). The average concentration of Hg in sediments of the bay around river mouths varied based on location, i.e. Bailang River was 0.0502 ppm, Sario River was 0.0270 ppm, Bahu River was 0.0615 ppm, and Malalayang River was 0.0143 ppm.Pertambangan emas rakyat menggunakan merkuri (Hg), yang berada di daerah dataran tinggi bagian Utara Pulau Sulawesi, membuang limbah tailing ke sungai menuju ke laut; satu dari sungai tersebut (Sungai Bailang) bermuara ke Teluk Manado. Hal ini dapat menyebabkan kontaminasi Hg ke lingkungan perairan teluk. Penelitian ini bertujuan untuk menilai kontaminasi Hg di ekosistem perairan teluk tersebut. Untuk penilaian, perairan teluk dibagi 2 bagian, yaitu bagian Utara dan Selatan, dan kontaminasi dinilai dengan cara mengukur konsentrasi Hg total pada sedimen dan ikan. Penentuan konsentrasi Hg mengacu Standar Nasional Indonesia (SNI) 01-2896-1992 dan Panduan Balai Riset dan Standarisasi Industri Manado. Hasil penelitian menunjukkan, bahwa kisaran konsentrasi Hg dalam ikan bervariasi berdasarkan jenis; dibagian Utara teluk: Holocentridae(0,1144-0,1151 ppm), Siganidae (0,0020-0,0034 ppm), Apogonidae (0,0461-0,050 ppm), dan Nemipterus (0,0142-0,0144 ppm).Sedangkandi perairan bagian Selatan teluk: Holocentridae (0,1090-0,1104 ppm), Siganidae (0,160-0,164 ppm), Apogonidae (0,1280-0,1291 ppm), Nemipterus (0,0522-0,0530 ppm),dan Priacanthus sp.(0,0194-0,0210 ppm). Konsentrasi rata-rata Hg di sedimen perairan teluk sekitar muara Sungai Bailang sebesar 0,0502 ppm, muara Sungai Sario sebesar 0,0270 ppm, muara Sungai Bahu sebesar 0,0615 ppm, dan muara Sungai Malalayang sebesar 0,0143 ppm.