Konsentrasi Timbal (Pb) dan Seng (Zn) Dalam Air Serta Partisi Geokimiawinya Pada Sedimen Permukaan Perairan Teluk Banten

Abstract

Teluk Banten menerima tekanan dari aktivitas pelabuhan, industri, perikanan, tambak, permukiman, dan masukan sungai. Karakter perairannya yang semi tertutup berpotensi menjadi perangkap material tersuspensi, bahan organik, dan logam berat. Penelitian ini bertujuan menganalisis konsentrasi, distribusi spasial, partisi geokimiawi, dan tingkat kontaminasi Pb dan Zn pada air dan sedimen permukaan Teluk Banten. Sampel air dan sedimen diambil pada lima stasiun yang mewakili muara sungai, tambak, tengah teluk, kawasan industri-pelabuhan, dan mangrove Pulau Panjang. Pb dan Zn dalam air dianalisis menggunakan ICP-MS, sedangkan partisi geokimiawi sedimen menggunakan SEP-BCR ke dalam fraksi terlarut asam/tertukar (F1), tereduksi (F2), teroksidasi (F3), dan residual (F4). Distribusi spasial dianalisis dengan interpolasi IDW, sedangkan tingkat kontaminasi dievaluasi menggunakan Enrichment Factor (EF), Indeks Geoakumulasi (Igeo), dan Faktor Kontaminasi (FK). Sedimen didominasi lanau 64,39–76,41%, lempung 21,96–27,47%, dan pasir 1,26–9,87%, dengan bahan organik 6,27–12,07%. Dominasi sedimen halus dan bahan organik menunjukkan kapasitas tinggi dalam mengadsorpsi dan mengakumulasi logam. Pb dalam air berada di bawah batas deteksi pada seluruh stasiun, sedangkan Zn berkisar <0,8–6,0 µg/L, keduanya masih di bawah baku mutu air laut. Pada sedimen, Pb mencapai 4,12–15,20 mg/kg dan Zn 245,64–1.222,71 mg/kg, jauh lebih tinggi daripada di kolom air. Konsentrasi tertinggi ditemukan di Stasiun 5, kawasan mangrove Pulau Panjang, yang berperan sebagai zona deposisi sedimen halus dan bahan organik. Hasil SEP-BCR menunjukkan Pb dan Zn terdistribusi pada fraksi non residual (F1–F3) dan residual (F4), dengan proporsi fraksi labil Zn lebih besar dibandingkan Pb. Perhitungan EF secara kondisional menunjukkan tidak ada pengayaan Pb pada seluruh stasiun. Untuk Zn S1dan S2 tidak menunjukkan pengayaan, S3–S4 menunjukkan pengayaan kecil, dan S5 menunjukkan pengayaan cukup berat. Igeo Pb pada seluruh stasiun berada pada kategori tidak tercemar. Igeo Zn menunjukkan kategori tercemar sedang pada S1dan S3, tercemar sedang–kuat pada S4, dan tercemar kuat pada S5. FK Pb menunjukkan kontaminasi rendah pada S1dan S4 dan sedang pada S5, sedangkan FK Zn menunjukkan kontaminasi cukup besar pada S1–S3 dan sangat tinggi pada S4 dan S5. Hasil penelitian menegaskan bahwa sedimen merupakan media akumulasi utama Pb dan Zn di Teluk Banten. Evaluasi pencemaran logam berat perlu memadukan konsentrasi total, partisi geokimiawi, dan indeks kontaminasi untuk memahami stabilitas, mobilitas, bioavailabilitas, serta potensi risiko ekologisnya.

Banten Bay receives pressures from port activities, industry, fisheries, aquaculture ponds, settlements, and riverine inputs. Its semi-enclosed characteristics potentially make the bay a trap for suspended materials, organic matter, and heavy metals. This study aimed to analyze the concentrations, spatial distribution, geochemical partitioning, and contamination levels of Pb and Zn in water and surface sediments of Banten Bay. Water and sediment samples were collected from five stations representing river mouths, aquaculture ponds, the central bay, industrial-port areas, and the mangrove area of Panjang Island. Pb and Zn in water were analyzed using ICP-MS, while geochemical partitioning in sediments was determined using SEP-BCR into acid-soluble/exchangeable (F1), reducible (F2), oxidizable (F3), and residual (F4) fractions. Spatial distribution was analyzed using IDW interpolation, while contamination levels were evaluated using the Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Contamination Factor (CF). The sediments were dominated by silt (64.39–76.41%), clay (21.96–27.47%), and sand (1.26–9.87%), with organic matter contents of 6.27–12.07%. The dominance of fine sediments and organic matter indicates a high capacity to adsorb and accumulate metals. Pb concentrations in water were below the detection limit at all stations, while Zn ranged from <0.8–6.0 µg/L; both remained below seawater quality standards. In sediments, Pb concentrations reached 4.12–15.20 mg/kg and Zn concentrations ranged from 245.64–1,222.71 mg/kg, considerably higher than those in the water column. The highest concentrations were found at Station 5, in the mangrove area of Panjang Island, which acts as a depositional zone for fine sediments and organic matter. SEP-BCR results showed that Pb and Zn were distributed among non-residual (F1–F3) and residual (F4) fractions, with a greater proportion of labile Zn fractions than Pb. Conditional EF calculations showed no Pb enrichment at all stations. For Zn, S1 and S2 showed no enrichment, S3–S4 showed minor enrichment, and S5 showed moderately severe enrichment. The Igeo values for Pb at all stations were categorized as uncontaminated. The Igeo values for Zn indicated moderately contaminated conditions at S1 and S3, moderately to strongly contaminated at S4, and strongly contaminated at S5. The CF values for Pb indicated low contamination at S1–S4 and moderate contamination at S5, whereas Zn showed considerable contamination at S1 and S3 and very high contamination at S4 and S5. The results confirm that sediments are the primary accumulation medium for Pb and Zn in Banten Bay. Heavy metal pollution assessment should integrate total concentrations, geochemical partitioning, and contamination indices to understand their stability, mobility, bioavailability, and potential ecological risks.