GRADASI PENCEMARAN SUNGAI BABON DENGAN BIOINDIKATOR MAKROZOOBENTOS

Abstract

ABSTRAK Gradasi Pencemaran Sungai Babon dengan Bioindikator Makrozoobentos. Sungai Babon adalah salah satu sungai di Semarang yang rentan terhadap pencemaran karena dari hulu sampai ke hilir banyak aktivitas yang berpotensi menurunkan kualitas airnya, misalnya pemukiman padat dan kegiatan industri. Sejak ditetapkan peruntukannya pada tahun 1994, sampai sekarang belum pernah dilakukan penilaian terhadap kondisi terkini sungai yang dibandingkan dengan penetapan peruntukan tersebut. Penelitian ini bertujuan untuk mengkaji karakteristik parameter makrozoobentos, air, dan sedimen ; melihat aktivitas manusia di sekitarnya yang berpengaruh terhadap kondisi air Sungai Babon serta melihat kesesuaian penetapan peruntukan Sungai Babon. Penelitian ini dilaksanakan pada bulan Maret sampai Mei 2010 diamati di bagian hulu Sungai Babon di Desa Kedungsari sampai dengan bagian hilir di dekat Bendung Karangroto sebanyak 6 stasiun pengamatan. Data yang dikoleksi di lapangan adalah : Salinitas, Suhu, Kecerahan, Kedalaman, pH, dan Kecepatan arus. Analisa di laboratorium dilakukan untuk identifikasi makrozoobentos, DO dan BOD, TOC sedimen, pH sedimen, N-total sedimen dan tekstur sedimen. Data peruntukan lahan di sekitar sungai diambil dengan wawancara dan observasi dilapangan. Berdasarkan penghitungan Indek BMWP-ASPT makrozoobentos, mutu perairan Sungai Babon dari bagian hulu termasuk dalam kategori cemar sedang, kemudian cemar ringan dan kembali menjadi cemar sedang di segmen tengah. Mendekati hilir menjadi cemar ringan dan menurun lagi menjadi cemar berat di stasiun paling hilir. Berdasarkan kriteria kelas air, nilai pH dan DO Sungai Babon termasuk kelas II, tetapi dari nilai BOD5 masuk dalam kiteria kelas III dan kelas IV. Hasil ini berbeda dengan penetapan peruntukan sungai Babon dalam SK Walikota No. 660.2992/ 1994 yang menetapkan kualitas sungai Babon menjadi 2 golongan yaitu sebelum bendung Pucanggading golongan B dan setelah Pucanggading golongan C. Berdasarkan analisa kluster, pola karakteristik parameter makrozoobentos di Sungai Babon tidak mirip dengan pola karakteristik sedimen maupun pola karakteristik air. Karakteristik parameter yang mirip dengan kelimpahan, H’ dan E makrozoobentos antara lain BOD, pH, suhu, kecerahan. Aktivitas manusia yang mempengaruhi kondisi kualitas Sungai Babon adalah: penambangan pasir dan batu, pembuangan sampah domestik dan pembuangan limbah pabrik di sekitar aliran Sungai Babon. Kegiatan pembuatan batubata tidak terlalu berdampak terhadap kualitas Sungai Babon karena dilihat dari Indek BMWP-ASPT di stasiun 4 dan 5 masuk dalam kriteria cemar sedang dan cemar ringan. Kata Kunci : Sungai Babon, makrozoobentos, karakteristik, peruntukan sungai ABSTRACT The Gradation of the Pollution of River Babon with Macrozoobenthos Indicator. River Babon is one of the rivers in Semarang with high risk of pollution. This is due to the fact that many activities potentially result in declining the river water quality from upstream to downstream. Among others, they include settlements and industries. The government had stipulated a regulation on environmental concern nearby the river. However, no condition assessment was currently performed. This study aimed to analyze the characteristics of macrozoobenthos, water, and sediment parameters as well as to observe human activities, which intervened the River Babon condition. In addition, the study also examined the compliance of the River Babon management to the regulation. This study took place at the upstream area of River Babon, Kedungsari Village and at the downstream area of the river in Karangroto from March to May 2010. The study performed six observation posts. Data collected from the field observation consisted of salinity, temperature, brightness, depth, pH, and stream speed. A laboratory analysis was performed to identify macrozoobenthos, sediment pH, DO and BOD, sediment TOC, sediment N-total, and sediment texture. The study also had interviews and on location observation to find out the implementation of and the compliance to the regulation nearby the river. According to a measurement of macrozoobenthos index issued by BMWP-ASPT the water quality of River Babon from upstream to downstream was considered lighty to extremely polluted. The index also showed that at the upstream river was fairly and lighty polluted ; middlestream river was fairly polluted; closing to the upstream lightly polluted; and at the edge of the upstream extremely polluted. According to river class criterion, the pH and DO rates of River Babon were categorized in Class II, whereas the BOD rate was categorized into both Class III and IV. These results were beyond the standard thresholds required by the ongoing regulation, Mayor Decree No. 600.2992/1994. According to a cluster analysis, the characteristic pattern of the macrozoobenthos parameters at River Babon were not similar to either sediment or water characteristics. Water parameters having a positive relationship with abundance, E and H macrozoobenthos were BOD, pH, temperature, brightnes. Human activities affecting the quality of River Babon included sand and stone mining, domestic waste disposal and industrial waste from factories situated nearby the River Babon. Brick industry activities at stations 4 and 5 did not significantly affect the water quality of the river because they only resulted in fair to light pollution, in particular, from BMWP-ASPT Index viewpoint. Keywords : River Babon, makrozoobenthos, characteristics, water used