KAJIAN HIDROKIMIA SEBARAN KROMIUM PADA LINGKUNGAN PERAIRAN DI SUNGAI SURABAYA
Yudhi Utomo, Drs.,M.Si., Prof. Dr. Sudarmadji, M.Eng.Sc.
2011 | Disertasi | S3 Ilmu LingkunganKajian hidrokimia sebaran kromium pada perairan Sungai Surabaya mulai dari Jembatan Canggu Mojokerto sampai dengan Pintu Air Jagir Surabaya. Penelitian ini bertujuan untuk (1) mengkaji parameter kualitas air terkait dengan sebaran Cr(VI) secara spasio-temporal pada perairan Sungai Surabaya; (2) mengkaji peranan Fe 3+ dan CO3 2- terhadap pengendapan Cr(III) serta Mn 2+ terhadap Cr(VI) secara laboratoris (3) mengkaji kandungan Cr sedimen dan biota ikan pada perairan Sungai Surabaya Penelitian hidrokimia sebaran kromium dilakukan dengan pendekatan kimia lingkungan. Tahapan kajian dilakukan untuk memperoleh jawaban secara komprehensif meliputi: (1) kajian kewilayahan, untuk memperoleh gambaran sumber bahan pencemar dan kondisi hidrologis yang mempengaruhi kualitas air Sungai Surabaya, (2) kajian hidrokimia, mempelajari parameter kualitas air Sungai Surabaya kaitannya dengan penyebaran kromium, 3) analisis peranan Fe 2+, CO3 2- dan Mn 2+ terhadap pengendapan kromium secara laboratoris, dan 4) analisis kandungan kromium dalam sedimen dan biota ikan di Sungai Surabaya. Metode penelitian yang dilakukan adalah survey lapangan dan eksperimen laboratorium. Hasil penelitian menunjukkan konsentrasi parameter kualitas air DO, BOD, COD, TDS, NH3-N, dan Cr(VI) di perairan Sungai Surabaya secara spasial-temporal berfluktuatif, secara umum kualitas air menurun yang disebabkan ; (1) volume dan konsentrasi limbah domestik ataupun industri di setiap lokasi dan waktu sampling berbeda, (2) terjadi proses fisika, kimia dan biologi dalam perairan bagian hulu ke hilir, (3) faktor pengenceran oleh kenaikan debit air sungai atau musim hujan. Hasil analisis statistik regresi-korelasi dan multivariat, berdasarkan nilai korelasi dan p-value pada α= 0,05 terdapat hubungan Cr(VI) dengan COD di Jembatan Canggu, sedangkan antar parameter kualitas air terdapat hubungan kuat yang berbeda pada masing-masing lokasi sampling. Secara laboratoris Fe 3+ dan CO3 2- cukup berperan dalam pengendapan Cr(III) pada rentang pH 7-9, sedangkan Mn 2+ berperan mereduksi konsentrasi Cr(VI) pada pH 6,2. Pada pH sangat basa (>10) Cr(OH)3 dapat larut kembali terbentuk CrO2-. Metode pengambilan sampel (sampling) untuk analisis kualitas air di Sungai Surabaya sebaiknya menggunakan composite sampling dengan memperhatikan morfologi sungai. Kadar Cr dalam sedimen tertinggi diperoleh 123 mg/kg massa kering, terdapat korelasi konsentrasi Cr di perairan dengan kandungan Cr dalam sedimen. Kandungan Cr dalam Ikan Gabus> Mujair> Bader dan ikan hidup di Bendungan Lengkong Baru> Karangpilang. Akumulasi Cr dalam ikan dipengaruhi (1) jenis ikan (2) kemampuan adaptasi dan makanan (3) territorial migrasi. Kromium termasuk logam berat yang dapat ditemukan di perairan dan sedimen serta dapat terakumulasi dalam biota ikan.
Research hydrochemical research of chromium distribution in the Surabaya River was carried out starting from Bridge of Canggu in Mojokerto up to the Floodgate of Jagir in Surabaya. This research had purposes to (1) study the quality parameter of water in relation to the distribution of Cr(VI) in a spatial-temporal manner in waters of Surabaya River; (2) laboratorical study of the role the Fe 3+ and CO3 2- in sedimentation of Cr(III) and the role of Mn 2+ on Cr(VI) (3) study the content of Cr in the sediment and the fish biota in waters of Surabaya River. The hydrochemical research of the distribution of chromium was carried out using the approach of environmental chemistry. To obtain the answer comprehensively the research was carried out by several stages, namely (1) territorial study to obtain the figure of pollution sources and hydrological condition towards the decline in the quality of the Surabaya River water, (2) hydrochemical study, to investigate the influence the quality parameter of water in the Surabaya River towards the distribution of the chromium, (3) the laboratory study of the Fe2+, CO3 2-and Mn 2+ factor effect on the process of the chromium sedimentation, and 4) the study of the content of chromium in sediment and the fish biota. The research method used in this study was field survey and experimental laboratory. Results of the research showed that the concentration of water quality parameters of DO, BOD, COD, TDS, NH3-N, and Cr(VI) in Surabaya River were spatial or temporally fluctuate, in general the water quality decreased that was caused; (1) domestic waste input and the industry in each location and every time the volume and his concentration were different (2) the occurrence of the physical, chemical and biologycal processes in waters while flowing from the upstream part to downstream, (3) the dilution factor induced by the water debit in river or the rain season. The better sampling method used for the analysis of the quality of water in the Surabaya River was composite sampling by paying attention to river morphology. Results of the analysis of statistics regression-correlation and multivariate, based on the correlation value and p-value at α = 0.05 indicated relations between Cr(VI) and COD in Canggu Bridge, whereas interpersonal of the quality parameters had strong correlation which were different with respect to the sampling location. Laboratory experiments showed Fe 3+ and CO3 2- played an important role in the sedimentation of Cr(III) that happened in an optimum condition of pH 7-9, whereas Mn 2+ played a role in reducing the concentration Cr(VI) at pH 6.2. At higher pH (>10) Cr(OH)3 redissolved to form CrO 2- . The highest level of Cr was in sediment which reached 123 mg/kg dry mass, there was a correlation between the concentration of Cr in waters and the content of Cr in sediment. The content of Cr in the Fish Striped nakehead>Oreochromis mosambicus>Barbonymus gonionatus and the fish live in the Bendungan Lengkong Baru > Karangpilang. The accumulation of Cr in the fish was affected by (1) the fish kind (2) the adaptation capacity and food (3) territorial the migration. Chromium was a heavy metal that could be found in waters, sediment and could be accumulated in the fish biota.
Kata Kunci : hidrokimia, kromium, kualitas air, sedimen, Sungai Surabaya
