ANALISIS SPASIAL PENCEMARAN LOGAM BERAT (Pb DAN Cd) PADA SEDIMEN ALIRAN SUNGAI DARI TEMPAT PEMBUANGAN AKHIR (TPA) SAMPAH JATIBARANG SEMARANG

Abstract

(TPA) Jatibarang merupakan sarana tempat pembuangan akhir sampah di Kota Semarang. Kandungan sampah yang beraneka ragam di TPA Jatibarang berpotensi besar di dalam pencemaran terhadap lingkungan. Hal ini bisa terjadi karena sampah yang terdekomposisi akan menghasilkan lindi (leachate). Lindi mengandung bahan organik maupun anorganik yang mengandung berbagai mineral dan logam seperti timbal (Pb) dan Kadmium (Cd). Kandungan logam berat ini mengalir bersama lindi masuk ke dalam sistem perairan dan mengalami proses sedimentasi di aliran Sungai Kreo. Penelitian ini bertujuan untuk mengetahui gambaran distribusi spasial, visualisasi, eksplorasi penyebaran logam berat (Pb dan Cd) pada sedimen aliran Sungai Kreo. Penelitian ini dirancang dengan pendekatan study cross sectional (potong lintang) dengan metode survei analitik. Pengambilan sampel lindi dilakukan pada outlet lindi sedangkan untuk sampel sedimen dilakukan pada 10 titik di sepanjang sungai Kreo. Titik 1 pada jarak 150 m sebelum pembuangan lindi (bagian hulu). Untuk titik ke dua dengan jarak 10 m, sedangkan titik ke tiga sampai dengan titik ke sepuluh dengan interval jarak kurang lebih 50 m, setelah pembuangan lindi. Pengambilan setiap titik dilakukan satu kali, pada 3 bagian yaitu bagian pinggir kanan, bagian tengah dan bagian pinggir kiri (sampel sesaat/grab sample). Hasil penelitian dengan AAS diperoleh hasil kadar Pb pada outlet lindi sebesar 0,136 mg/lt, kadar Cd 0,09 mg/lt. Kadar Pb dalam sedimen pada jarak 150 m sebelum outlet lindi 0,011 mg/kg, sedangkan kadar Cd = 0,000 mg/kg, jarak 10 m kadar Pb = 2,319 mg/kg, Cd = 0,019 mg/kg, jarak 67 m kadar Pb = 1,425 mg/kg, Cd = 0,018 mg/kg, jarak 143 m kadar Pb = 2,195 mg/kg, Cd = 0,019 mg/kg, jarak 225 m kadar Pb = 1,546 mg/kg, Cd = 0,012 mg/kg, jarak 282 m kadar Pb = 1,401 mg/kg, Cd = 0,009 mg/kg, jarak 365 meter kadar Pb = 1,079 mg/kg, Cd = 0,008 mg/kg, jarak 462 m kadar Pb = 0,728 mg/kg, Cd = 0,006 mg/kg, jarak 520 m kadar Pb = 0,961 mg/kg, Cd = 0,008 mg/kg, jarak 580 m kadar Pb = 0,604 mg/kg, Cd = 0,005 mg/kg. Hasil analisa dengan Uji Beda (T – Test) menunjukkan ada beda antara kadar Pb pada lindi dan kadar Pb pada sedimen (p = 0,0001), ada beda kadar Cd pada lindi dan kadar Cd pada sedimen (p = 0,0001) dan pada uji regresi ada hubungan antara jarak outlet lindi dengan kadar Pb pada sedimen (p = 0,0001 dan r2 = 0,932) dan kadar Cd pada sedimen (p = 0,0001 dan r2 = 0,907). Hasil analisis spasial kelas pencemaran tinggi Pb dan Cd (total) pada sedimen aliran Sungai Kreo terjadi mulai dari jarak 0 m sampai dengan jarak 143 m dari outlet lindi. Kelas sedang dimulai dari jarak 143 m sampai dengan jarak 365 m. Kelas rendah dimulai dari jarak 365 m sampai dengan jarak 580 m sepanjang aliran Sungai Kreo. Perlu pengolahan lindi sebelum lindi masuk ke aliran Sungai Kreo dan monitor secara rutin kadar logam berat (Pb dan Cd) pada aliran Sungai Kreo. The FWD of Jatibarang is the final waste disposal for the city of Semarang. Contained with varied chemical element, this FWD may raise environment pollution. It can be happened because of the decomposed waste produces leachate. Leachate contains organic and inorganic elements. Organic elements contain minerals and metals. One of the metals within the leachate can be such heavy metals as Lead (Pb) and Cadmium (Cd). These heavy metals content stream down together with leachate into the irrigation system and undergoing a sedimentation process in Kreo River stream. The purpose of this study is to find out the description of the spatial distribution, the visualization, and the spreading exploration of the heavy metals (Pb and Cd) within the sediment of Kreo River stream. This study utilizes study cross sectional approach by using analytical survey. Leachate sampling is undergone once at the leachate outlet while the sediment sampling is undergone at ten spots of the Kreo River. The first spot is 150 meters from the leachate disposal (upper stream). The second spot to the tenth spot are within the interval distance of less then 50 meters after the leachate disposal. Each spot taking is undergone once at the three parts of the right edge, middle edge, and left edge of the grab sample. The inspection using AAS collects the concentration of Pb at the leachate outlet 0.136 mg/l, concentration of Cd is 0.09 mg/l. The concentration of Pb within the sediment at 150 meters before the leachate outlet is 0.011 mg/kg, while the concentrationl of Cd = 0.000 mg/kg. Within 10 meters from the leachate outlet, the concentration of Pb = 2.319 mg/kg, Cd = 0.019 mg/kg. Within 67 meters from from the outlet, the concentration of Pb = 1.425 mg/kg, Cd = 0.018 mg/kg. Within 143 meters from the outlet, the concentration of Pb = 2.195 mg/kg, Cd = 0.019 mg/kg. Within 225 meters from the outlet, the concentration of Pb = 1.546 mg/kg, Cd = 0.012 mg/kg. Within 282 meters from the outlet, the concentration of Pb = 1.401 mg/kg, Cd = 0.009 mg/kg. Within 365 meters from the outlet, the concentration of Pb = 1.079 mg/kg, Cd = 0.08 mg/kg. Within 580 meters from the outlet, the concentration of Pb = 0.604 mg/kg, Cd = 0.005 mg/kg. The result from the Differential Test (T – Test) show that there are concentration of Pb within the leachate and the concentration of Pb within the sediment (p = 0.0001). There are also concentration of Cd within the leachate and the concentration of Cd within the sediment (p = 0.0001). There is a distance relation between the l332 leachate outlet and the level of Pb within the sediment in the regression test, (p = 0.0001 and r2 = 0.932), and the concentration of Cd within the sediment (p = 0.0001 and r2 = 0.907). The spatial analysis results the highest class of Pb and Cd pollution (totally) within the sediment of the Kreo River stream started from 0 meter to 143 meters from the leachate outlet. The medium class pollution starts from 143 meters to 365 meters. The lower class pollution starts from 365 meters to 580 meters along the Kreo River stream. It needs more leachate treating before the leachate entering the Kreo River stream and regular monitoring upon the level of heavy metal (Pb and Cd) within the Kreo River stream.