DISTRIBUTION AND TRANSLOCATION OF HEAVY METALS IN SOIL IRRIGATED WITH TREATED WASTEWATER IN BRAUNSCHWEIG

Puji Lestari, Prof. Dr. Endang Tri Wahyuni, M.S.

2014 | Tesis | S2 Ilmu Kimia

Telah dilakukan studi tentang distribusi dan translokasi logam berat di dalam tanah yang dialiri air limbah di Braunschweig. Air limbah yang digunakan merupakan air limbah domestik dan industri di Braunschweig. Sebelum digunakan untuk irigasi, air limbah diolah di instalasi pengolahan air limbah Steinhof (wastewater treatment plant, WWTP). Sampel tanah diambil dari area Steinhof WWTP yang terletak di baratdaya Braunshweig. Tanah yang tidak dialiri air limbah juga dianalisis sebagai pembanding. Tanah yang berukuran > 2 mm tidak diikutsertakan dalam analisis. Semua sampel tanah dianalisis keasmannya (pH) dalam larutan CaCl2 0,01M, distribusi ukuran butiran tanah menggunakan metode penyaringan basah dan metode pengendapan, serta analisis konsentrasi elemen yang terekstrak menggunakan aqua regia (3:1, v/v, HCl 32% : HNO3 65%). Konsentrasi elemen dalam larutan dianalisis menggunakan ICP/OES. pH sampel tanah berkisar antara 4,9 hingga 6,8. Sampel tanah didominasi oleh pasir dengan kandungan pasir berkisar antara 75 – 97%. Konsentrasi logam berat pada lapisan atas tanah yang diirigasi air limbah lebih tinggi daripada konsentrasi logam berat pada tanah tanpa irigasi. Terdapat hubungan linier antara konsentrasi logam berat (Al, Fe dan Zn) dengan kandungan silt dalam tanah. Terdapat hubungan logaritmik antara Cd, Cu, Pb dan Zn dengan kandungan organik tanah. Terdapat pula hubungan linier antar elemen seperti Fe dan Al, Al dan Zn, Zn dan Pb, Sr, P dan Ca dan P dengan Ca dan Pb. Enrichment factor (EF) untuk beberapa logam berat dihitung menggunakan Al sebagai unsur acuan (normalizing element). Hasil perhitungan menunjukkan nilai EF logam berat pada sampel tanah lebih tinggi daripada tanah pembanding. Hal ini mengindikasikan bahwa aplikasi air limbah dalam jangka waktu yang lama dapat meningkatkan konsentrasi logam berat di dalam tanah.

The study to investigate the distribution and translocation of heavy metals in the wastewater irrigated soils in Braunschweig has been carried out. The wastewater used for irrigation was the previously treated domestic and industrial wastewater from Braunschweig. The soil samples were taken from the Steinhof wastewater treatment plant (WWTP) area in the northwest of Braunschweig, Germany. The non-irrigated soil was also analyzed as a comparison. The soil fraction > 2 mm was excluded from analysis through sieving. All soil samples were analyzed for the pH values in 0.01M CaCl2 solution, grain size distribution (using wet sieving and settling methods), and the concentration of their aqua regia (3:1, v/v, HCl 32% to HNO3 65%) extractable elements. The concentration of aqua regia extractable elements was analyzed using ICP/OES instrument. The pH values of soil samples ranged from 4.9 to 6.8. The soil samples are dominated by sand fraction with the content in the range of 75 – 97%. The concentrations of heavy metals in the top soils of irrigated areas are generally higher than the concentrations of heavy metal in the reference areas, indicating the heavy metals enrichment on top soils due to the long term application of wastewater. There is a linear correlation between heavy metals (Al, Fe and Zn) and silt fraction. A second-order correlation was found between aqua regia extractable elements (Cd, Cu, Pb and Zn) and the organic content of the soil. There is also a linear correlation between inter-element such as Fe versus Al, Al versus Zn, Zn versus Pb, Sr, P and Ca and for P versus Ca and Pb. The enrichment factors (EFs) of some heavy metals calculated using Al as the normalizing element revealed that the EFs of heavy metal in soil samples are higher than those of the references. This indicated that the long-term application of wastewater has elevated the concentration of heavy metals in the soil.

Kata Kunci : tanah, irigasi air limbah, distribusi ukuran butiran, logam berat, ICP/OES.