Sains Malaysiana 38(6)(2009): 841–850

Kepekatan Kandungan Logam Berat dalam Tanih di Tapak Pelupusan  Sampah Sg. Kembong, Bangi, Selangor

(Heavy Metal Concentration in Soil at Sg. Kembong Landfill, Bangi, Selangor)

Natrah Mohamed, Umar Hamzah* & Sahibin Abd Rahim

Pusat Pengajian Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E., Malaysia

Diserahkan: 17 Julai 2007 / Diterima: 4 Mei 2009

ABSTRAK

Analisis taburan kepekatan logam berat dalam tanih, sifat fiziko-kimia sampel tanih dan survei keberintangan geoelektrik 2D di tapak pelupusan sampah Sungai Kembong telah dilakukan untuk melihat kesan larut lesap logam berat di sekitar tapak pelupusan tersebut. Jumlah sampel tanih yang dikutip untuk analisis fiziko kimia dan analisis logam berat adalah 30 dan diambil dari kedalaman 60 cm di bahagian tapak yang tidak aktif dan telah ditimbus. Survei keberintangan geoelektrik telah dilakukan dengan teknik susun atur Wenner dan teknik pengimejan 2D. Jarak antara elektrod ialah 5 m dan jumlah panjang garis rentas adalah 300 m. Analisis sampel tanih menunjukkan kandungan pasir adalah 25 - 75%, manakala kandungan lempung adalah 5 – 41% dan kandungan kelodak pula adalah 19-67%. Hasil analisis logam berat menunjukkan kepekatan logam Cu, Pb dan Cr melebihi paras normal manakala logam lain seperti Ni, Co, Cd, Zn dan Fe berada pada julat normal. Kepekatan Cu adalah 2-326 μg/g manakala kepekatan Pb dan Cr masing-masing adalah 3-78 μg/g dan 4-76 μg/g. Model 2D songsang sepanjang garisan rentasan menunjukkan julat keberintangan antara 5 Ωm sehingga 105 Ωm. Julat keberintangan bahan larut lesap adalah sekitar 3 - 5 Ωm. Purata ketebalan bahan larut lesap dianggarkan sekitar 20 hingga 100 m. Nilai purataKPK adalah pada julat 1.73 hingga 3.85 meq/100. Manakala pH pada julat 4 hingga 7. Kekonduksian elektrik menunjukkan bacaan antara 1910-5525 μS/cm. BOT dalam sampel menunjukkan nilai yang rendah iaitu 0.3-5.6%. Kajian mineralogi menggunakan pembelauan sinar-X (XRD), menunjukkan kandungan mineral terdiri daripada muskovit, kuarza, kaolinit dan ortoklas. Mineral-mineral ini ditafsirkan berasal dari tanah penutup yang diambil dari batuan metasedimen di perbukitan sekitar tapak kajian. Hasil kajian menunjukkan tanah yang digunakan berjaya mengawal pergerakan logam-logam berat dari meresap ke kawasan sekitar.

Kata kunci: Larut lesap; logam berat; sifat fiziko-kimia tanih; tapak pelupusan sampah

ABSTRACT

The distribution of heavy metals in soils, physico-chemical properties of soils and 2D geoelectrical resistivity survey at Sungai Kembong sanitary landfill were analyzed in order to investigate the effect of heavy metals in the leachate around the dumping site. A total of 30 soil samples were collected for physico-chemical and heavy metals analysis by hand auger from a depth of about 60 cm in the ground within the covered inactive landfill. Geoelectrical resistivity survey was carried out using Wenner electrode array and 2-D imaging technique. Electrode spacing used was 5 m along 300 m line. The soil samples contained about 25 – 75% of sand, 4 – 40% of clay and 19 – 67% of silt. Results of heavy metals analysis showed that the concentrations of Cu, Pb and Cr were higher than the background level while other metals such as Ni, Co, Cd, Zn and Fe were lower than the background values. The range of Cu concentrations is 2-326 μg/g while Pb and Cr are 3-78 μg/g and 4-76 μg/g, respectively. The range of resistivity based on 2D inversed model along the survey line is from 5 Ωm to 105 Ωm. Resistivity values of 3 to 5 Ωm were interpreted as representing leachate plume. The width of leachate plumes was between 20 to 100 m. The average value of CEC is from 1.7 to 3.8 meq/100 and the pH value ranged from 4 to 7. The electrical conductivity is in between 1910 to 5525 μS/cm. The organic matter in the soil is ranged from 0.3 to 5.6%. Muscovite, quartz, kaolinite and orthoclase minerals were found dominant in the XRD patterns of the samples. These minerals were interpreted as coming from the covering metasediment soil taken from the surrounding areas. These results showed that the soil cover used in the dumping site managed to control the heavy metals from infiltrating into the surrounding areas.

Keywords: Heavy metals; landfill; leachate; physico-chemical properties soil

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*Pengarang untuk surat-menyurat; email: umar@ukm.my