Analisis Pencemaran Logam Berat dan Risiko Ekologis di Sedimen Estuaria Sungai Comal

Abstract

Aktivitas antropogenik di kawasan pesisir Desa Mojo, Estuari Sungai Comal, berpotensi meningkatkan masukan logam berat ke lingkungan perairan. Sedimen di muara berperan sebagai penyerap dan penyimpan utama logam berat, sehingga mencerminkan tingkat pencemaran dan risiko ekologis perairan. Penelitian ini bertujuan menilai status pencemaran dan potensi risiko ekologis logam timbal (Pb), arsen (As), kobalt (Co), dan kromium (Cr) pada sedimen permukaan Estuari Sungai Comal, Pemalang. Sebanyak sepuluh stasiun pengambilan sampel ditentukan secara acak sepanjang muara. Analisis logam dilakukan menggunakan metode aqua regia dan diukur dengan Flame Atomic Absorption Spectrophotometry (FAAS). Evaluasi kontaminasi dilakukan melalui perhitungan Contamination Factor (CF), Geoaccumulation Index (Igeo), Pollution Load Index (PLI), dan Ecological Risk Index (RI). Hasil menunjukkan bahwa konsentrasi Pb (0,10–0,23 mg/kg), As (0,38–0,59 mg/kg), Co (0,10–0,14 mg/kg), dan Cr (0,25–0,58 mg/kg) berada jauh di bawah nilai Interim Sediment Quality Guidelines (ISQG). Nilai CF<1, Igeo≤0, dan PLI<1 menandakan kontaminasi rendah, sedangkan RI (0,37–0,55) menunjukkan risiko ekologis sangat rendah. Secara spasial, akumulasi logam cenderung meningkat ke arah laut akibat transportasi dan deposisi sedimen. Hasil ini menunjukkan bahwa sedimen Estuari Sungai Comal belum tercemar signifikan, namun pemantauan berkala tetap diperlukan terhadap perubahan kualitas sedimen akibat dinamika pasang surut dan aktivitas antropogenik.

Anthropogenic activities in the coastal area of Mojo Village, at the Comal River estuary, potentially increase heavy metal inputs into the aquatic environment. Estuarine sediments act as major sinks and reservoirs of heavy metals, reflecting the degree of contamination and ecological risk. This study aims to assess the pollution status and potential ecological risk of lead (Pb), arsenic (As), cobalt (Co), and chromium (Cr) in surface sediments of the Comal River estuary, Pemalang. Ten sampling stations were randomly selected along the estuary. Metal concentrations were determined using aqua regia digestion followed by Flame Atomic Absorption Spectrophotometry (FAAS). Contamination was evaluated using the Contamination Factor (CF), Geoaccumulation Index (Igeo), Pollution Load Index (PLI), and Ecological Risk Index (RI). The concentrations of Pb (0,10–0,23 mg/kg), As (0,38–0,59 mg/kg), Co (0,10–0,14 mg/kg), and Cr (0,25–0,58 mg/kg) were well below the Interim Sediment Quality Guidelines (ISQG). Values of CF<1, Igeo≤0, and PLI<1 indicated low contamination, while RI (0,37–0,55) suggested a very low ecological risk. Spatially, metal accumulation increased seaward, associated with sediment transport and deposition. Overall, the Comal River estuarine sediments remain unpolluted, though continuous monitoring is recommended due to tidal dynamics and ongoing anthropogenic pressures.