Electronic Theses and Dissertation

DAS Krueng Seunagan merupakan salah satu Daerah Aliran Sungai strategis di Kabupaten Nagan Raya, Provinsi Aceh, yang dimanfaatkan masyarakat untuk kebutuhan irigasi pertanian, air baku, dan perikanan. Aktivitas pertambangan emas rakyat di sekitar Sub-DAS Krueng Isep serta kegiatan perkebunan, pertanian, dan permukiman di Sub-DAS Seunagan Hilir berpotensi menjadi sumber masukan logam berat Timbal (Pb) ke badan air sungai. Timbal merupakan logam berat unsur kimia berbahaya dengan densitas tinggi tidak dapat terurai yang bersifat toksik dan akumulatif, sehingga paparan jangka panjang melalui air irigasi maupun rantai makanan dapat menimbulkan dampak berbahaya terhadap kesehatan manusia dan keseimbangan ekosistem perairan. Penelitian ini bertujuan untuk menganalisis konsentrasi logam berat Timbal (Pb) pada air sungai di DAS Krueng Seunagan dan memetakan distribusi spasialnya menggunakan perangkat lunak ArcGIS.
Pengambilan sampel dilakukan pada 10 titik yang ditentukan secara purposif, mencakup empat titik di Sub-DAS Seunagan Hilir dan enam titik di Sub-DAS Krueng Isep, dengan mempertimbangkan keterwakilan kondisi aliran dari hulu ke hilir serta kedekatan dengan potensi sumber pencemar. Analisis kandungan Pb dilaksanakan di laboratorium Keamanan Pangan Dinas Pangan Aceh menggunakan metode Spektrofotometri Serapan Atom (SSA) dengan instrumen Shimadzu AA-7000 pada panjang gelombang 283,3 nm. Pemetaan sebaran dilakukan dengan metode interpolasi Inverse Distance Weighting (IDW) menggunakan nilai power parameter (p) sebesar 2, kemudian hasil interpolasi diklasifikasikan berdasarkan baku mutu air permukaan sesuai Peraturan Pemerintah Nomor 22 Tahun 2021 dan Peraturan Menteri Kesehatan Nomor 2 Tahun 2023.
Hasil analisis laboratorium menunjukkan bahwa konsentrasi Pb pada seluruh 10 titik sampel berkisar antara 0,168 mg/L hingga 0,275 mg/L dengan nilai rata-rata sebesar 0,226 mg/L. Seluruh titik sampel telah melampaui baku mutu air permukaan Kelas I hingga Kelas III dari ambang batas yang ditetapkan (0,03 mg/L), namun masih berada di bawah baku mutu Kelas IV (0,50 mg/L). Sub-DAS Krueng Isep mencatat rata-rata konsentrasi Pb lebih tinggi (0,245 mg/L) dibandingkan Sub-DAS Seunagan Hilir (0,197 mg/L). Peta interpolasi IDW memperlihatkan zona konsentrasi tertinggi (>0,250 mg/L) terkonsentrasi di bagian hulu Sub-DAS Krueng Isep yang berdekatan dengan kawasan pertambangan emas rakyat, dengan pola penurunan konsentrasi seiring bertambahnya jarak menuju hilir. Seluruh wilayah penelitian terklasifikasi dalam kategori tinggi (melampaui baku mutu Kelas I–III), yang menunjukkan bahwa konsentrasi Pb di wilayah penelitian telah melebihi ambang batas untuk peruntukan air pada kelas tersebut. Hasil penelitian ini diharapkan dapat menjadi dasar ilmiah bagi pengelolaan kualitas lingkungan dan perumusan kebijakan pengendalian pencemaran logam berat di DAS Krueng Seunagan.

The Krueng Seunagan Watershed is one of the strategic watersheds in Nagan Raya Regency, Aceh Province, Indonesia, serving as an important water resource for agricultural irrigation, raw water supply, and fisheries. Artisanal and small-scale gold mining (ASGM) activities in the Krueng Isep Sub-watershed, together with plantation, agricultural, and residential activities in the Seunagan Hilir Sub-watershed, are potential sources of Lead (Pb) contamination in the river system. Lead is a hazardous heavy metal with high density that is non-biodegradable, toxic, and accumulative. Therefore, long-term exposure through irrigation water and the food chain may pose serious risks to human health and the balance of aquatic ecosystems. This study aimed to analyze the concentration of Lead (Pb) in the river water of the Krueng Seunagan Watershed and to map its spatial distribution using ArcGIS software. Water samples were collected from 10 purposively selected sampling points, consisting of four locations in the Seunagan Hilir Sub-watershed and six locations in the Krueng Isep Sub-watershed. The sampling locations were selected to represent upstream-to-downstream flow conditions and their proximity to potential pollution sources. Lead (Pb) concentrations were analyzed at the Food Safety Laboratory of the Aceh Food Agency using the Atomic Absorption Spectrophotometry (AAS) method with a Shimadzu AA-7000 instrument at a wavelength of 283.3 nm. Spatial distribution mapping was performed using the Inverse Distance Weighting (IDW) interpolation method with a power parameter (p) of 2. The interpolation results were then classified according to the surface water quality standards stipulated in Government Regulation of the Republic of Indonesia Number 22 of 2021 and the Regulation of the Minister of Health of the Republic of Indonesia Number 2 of 2023. The laboratory analysis showed that Pb concentrations at all 10 sampling points ranged from 0.168 mg/L to 0.275 mg/L, with an average concentration of 0.226 mg/L. All sampling points exceeded the Class I to Class III surface water quality standards (0.03 mg/L), but remained below the Class IV standard (0.50 mg/L). The Krueng Isep Sub-watershed exhibited a higher average Pb concentration (0.245 mg/L) than the Seunagan Hilir Sub-watershed (0.197 mg/L). The IDW interpolation map revealed that the highest Pb concentration zone (>0.250 mg/L) was concentrated in the upstream area of the Krueng Isep Sub-watershed, adjacent to artisanal gold mining sites, with concentrations gradually decreasing toward the downstream area. The entire study area was classified as having high Pb concentrations, exceeding the Class I–III surface water quality standards, indicating that Pb levels throughout the study area surpassed the permissible limits for these designated water-use classes. The findings of this study are expected to provide a scientific basis for environmental quality management and the development of policies for controlling heavy metal pollution in the Krueng Seunagan Watershed.