SPESIASI DAN BIOAVAILABILITAS LOGAM BERAT DALAM SEDIMEN SUNGAI ROOMO GRESIK

Aliran Sungai Roomo telah tercemar oleh bahan-bahan organik terutama dari limbah domestik dan industri.Cemaran logam berat juga dipastikan ada dalam sungai tersebut.Logam berat ini masuk ke dalam sedimen dan biota yang hidup di lingkungan tersebut dan dapat terakumulasi pada seluruh bagian tubuhnya.Tujuan penelitian ini adalah untuk menentukan tingkat pencemaran logam Pb, Cd, dan Cu dalam air dan sedimen Sungai Roomo Gresik serta menganalisis biovailabilitas logam berat tersebut.Metode ekstraksi bertahap dan digesti basah digunakan untuk melakukan spesiasi dan ekstraksi logam dari sedimen serta konsentrasi logamnya diukur menggunakan Spektrofotometer Serapan Atom (AAS). Kandungan logam Pb, Cd, dan Cu dalam aliran sungai Roomo Gresik telah melebihi batas yang diperbolehkan, yaitu  berturut-turut 1,6038-7,8365 mg/L; 0,0251–0,0798 mg/L; dan 0,1709–0,2249 mg/L dalam air dan 213,7750–539,0763 mg/kg; 3,3467–39,7071 mg/kg; dan 36,9168-190,7079 mg/kg dalam sedimen. Pola spesiasi logam berat tersebut sebagai F1 atau fraksi EFLE (easily, freely, leachable, exchangeable), F2 (reducible), F3 (oxidisable), dan F4 (resistant) adalah sebagai berikut: F4 > F2 > F1 > F3 untuk Pb dan Cd, sedangkan Cu dengan pola F3 > F4 > F2 > F1. Logam Pb, Cd, dan Cu yang bioavailable berturut-turut 2,78-7,11%, 1,98-20,44%, dan 2,48-13,66%, sementara yang berpotensi bioavailable berturut-turut 10,05-16,81%; 9,41-54,44%; dan 15,18-94,19%. Logam Pb, Cd, dan Cu yang non bioavailable berturut-turut 79,53-84,22%, 25,11-86,04%, dan 1,84-80,67%. Dengan demikian, Sungai Roomo Gresik telah tergolong sebagai sungai yang tercemar. Kata kunci: biavailabilitas, logam berat, sedimen, spesiasi, sungai The Roomo River Stream has been polluted by organic materials which were mainly from domestic and industrial waste. Heavy metals were also ensured contaminated the river. These heavy metals enter sediments and can accumulate in the biota living in the river. This study was aimed to determine the level of pollution of Pb, Cd, and Cu metals in the water and sediments of the Roomo Gresik River and to analyze the biovability of these heavy metals. The sequential extraction and wet digestion method were used to perform a speciation and extraction of the metals from sediments. The concentration of the metals was measured by the use of Atomic Absorption Spectrophotometer (AAS). The contents of Pb, Cd, and Cu metals in the river were exceeded the allowed limit, which were 1.6038-7.8365 mg/L; 0.0251-0.0798 mg/L; and 0.1709-0.2249 mg/L, respectively in water and 213.7750-539763 mg/kg; 3.3467–39.7071 mg/kg; and 36.9168-190.7079 mg/kg, respectively in sediments. The pattern of heavy metal speciations as F1 or EFLE fraction (easily, freely, leachable, exchangeable), F2 (reducible), F3 (oxidizable), and F4 (resistant) were as follows: F4>F2>F1>F3 for Pb and Cd, whereas Cu with the pattern of F3>F4>F2>F1. The percentages of bioavailability of Pb, Cd, and Cu metals including readily biavailable were 2.78-7.11%, 1.98-20.44%, and 2.48-13.66%, potentially bioavailable were 10.05-16.81%, 9.41-54.44%, and 15.18-94.19%. Non-bioavailable were 79.53-84.22%, 25.11-86.04% and 1.84-80.67%, respectively. Therefore, the Roomo Gresik River has been classified as a polluted river. Keywords: bioavailability, heavy metals, river, sediment, speciation