Fitratian, Rifnida Azmi (2019) Sifat Fisika–Kimia Tanah Sebagai Indikator Ketersediaan Logam Berat Cu dan Zn di Badan Air. Magister thesis, Universitas Brawijaya.
Abstract
Tanah merupakan salah satu tempat penyimpan bahan–bahan pencemar yang diakibatkan oleh aktivitas alamiah maupun manusia. Distribusi polutan di tanah tergantung pada sifat fisika–kimia tanah, antara lain pH, bahan organik, kapasitas tukar kation (KTK), potensial redoks dan ukuran partikel tanah. Adanya perubahan kondisi lingkungan, misalnya alih guna lahan, menyebabkan perubahan sifat fisika dan kimia tanah sehingga mempengaruhi mobilitas polutan yang ada di tanah menuju badan air. Salah satu polutan yang ada di tanah adalah logam berat. Cu dan Zn merupakan logam berat esensial yang dibutuhkan oleh organisme dalam konsentrasi kecil. Logam tersebut dapat menimbulkan efek racun jika dalam jumlah yang berlebihan. Di tanah, logam berat terdapat dalam berbagai fraksi. Penentuan fraksi geokimia logam berat dalam tanah penting untuk menilai potensi toksisitasnya. Fraksi logam berat di tanah adalah fraksi exchangeable dan terikat karbonat (F1), fraksi reducible atau Fe-Mn oksida (F2), fraksi oxidisable atau terikat pada bahan organik (F3), dan fraksi residual (F4). Fraksi 1 hingga 3 logam berat dalam tanah merupakan fraksi nonresisten. Logam berat dalam fraksi nonresisten bersifat labil, mobilitasnya tinggi, dan dapat diadsorpsi oleh biota. Distribusi fraksi geokimia logam berat dalam tanah dipengaruhi oleh sifat fisika dan kimia tanah. Dengan mengetahui sifat fisika–kimia tanah yang dominan terhadap fraksi nonresisten serta potensi resiko tanah maka dapat diprediksi tingkat ketersediaan logam berat di badan air yang berasal dari tanah. Penelitian yang telah dilakukan bertujuan untuk mengevaluasi potensi tanah sebagai indikator ketersediaan logam berat di badan air. Masalah yang dipecahkan dalam penelitian adalah penentuan sifat fisika–kimia tanah, penentuan distribusi fraksi geokimia logam Cu dan Zn dalam tanah, penentuan sifat fisika–kimia tanah yang dominan berkorelasi positif terhadap fraksi geokimia Cu dan Zn di tanah, dan penentuan potensi resiko tanah menggunakan nilai Risk Assessment Code (RAC). Sampel tanah diambil dari Sumber Nyolo. Sumber Nyolo terletak di desa Ngenep, Kecamatan Karangploso, Kabupaten Malang merupakan lahan agroforestri yang di dalamnya terdapat sumber mata air yang banyak dimanfaatkan oleh warga sekitar untuk berbagai aktivitas yaitu digunakan untuk aktivitas rumah tangga, irigasi sawah dan perkebunan. Sifat fisika–kimia tanah yang ditentukan adalah tekstur tanah, pH tanah, potensial redoks, bahan organik tanah, dan kapasitas tukar kation (KTK). Metode yang digunakan dalam penentuan fraksi geokimia logam berat Cu dan Zn adalah metode ekstraksi bertahap Community Bureau of Reference (BCR) termodifikasi dengan pembagian menjadi empat fraksi logam berat. Korelasi sifat fisika–kimia tanah terhadap konsentrasi fraksi geokimia tanah dianalisis menggunakan uji korelasi Pearson. Potensi resiko tanah sebagai sumber logam berat bagi perairan dapat dievaluasi menggunakan nilai RAC yang merupakan persentase fraksi 1 terhadap total fraksi logam berat di tanah. Hasil penelitian menunjukkan bahwa sifat fisika–kimia tanah di Sumber Nyolo yaitu tanah di lokasi yang diteliti mempunyai pH netral (6,9–7,4). Pada pH tersebut, koloid oksi/hidroksi tanah terdapat dalam bentuk Fe2O3 dan FeOOH yang dapat mengikat logam berat. Nilai potensial redoks tanah berkisar antara 310 mV–335 mV menunjukkan bahwa tanah di Sumber Nyolo dalam kondisi teroksidasi dan oksik. Tanah yang diamati mempunyai ukuran partikel liat yaitu berkisar 30%–55% dan bahan organik tanah sebesar 3,67%–4,55%. Hal ini menghasilkan nilai KTK tanah sebesar 27,87 meq/100g–31,97 meq/100g. Sebagai akibatnya, tanah di Sumber Nyolo dapat menyerap logam berat melalui pembentukan senyawa kompleks dengan bahan organik tanah dan melalui pertukaran ion dengan kation–kation tanah. Berdasarkan persen distribusi fraksi, logam Cu dominan dalam bentuk fraksi resisten (F4) (57%), sedangkan logam Zn yang dominan sebagai fraksi nonresisten (F1, F2, dan F3) (59%). Sebagai fraksi dengan mobilitas tinggi (F1) logam Cu lebih dominan dibandingkan dengan logam Zn. Hal ini berarti Cu mempunyai mobilitas lebih besar daripada Zn, sehingga logam Cu lebih mudah lepas ke badan air. Hasil uji korelasi Pearson menunjukkan bahwa pH, potensial redoks, dan KTK berkorelasi positif terhadap fraksi nonresisten Cu dan Zn, sehingga perubahan sifat–sifat tersebut dapat menyebabkan mobilisasi Cu dan Zn dari tanah ke badan air. Namun berdasarkan nilai RAC dan sifat fisika–kimia yang dimiliki, tanah di Sumber Nyolo tidak berpotensi dalam menyediakan Cu dan Zn di badan air, dengan nilai RAC Cu dan Zn masing–masing sebesar 0,13% dan 0,04%. Berdasarkan hasil yang didapatkan dapat disimpulkan bahwa dengan mengetahui sifat fisika dan kimia tanah yang berkorelasi positif terhadap fraksi nonresisten Cu dan Zn dalam tanah, tanah merupakan indikator bagi ketersediaan Cu dan Zn di badan air.
English Abstract
Soil can act as a pollutants reservoir caused by natural and human activities. The distribution of pollutants in soil depends on the physical–chemical properties of the soil, including pH, organic matter, cation exchange capacity (CEC), redox potential, and soil particle size. There is change in environmental conditions, such as land use change, causing changes in the physical and chemical properties of the soil which affect the mobility of pollutants in the soil to water body. Such of the pollutants in soil is heavy metals. Cu and Zn are essential heavy metals needed by organisms at low concentration. The metals can cause toxic effects if in excessive amounts. In soil, heavy metals are found in various fractions. Determination of geochemical fractions of heavy metals in the soil is important to assess its potential for toxicity. Heavy metal in soil is fractionated into exchangeable and carbonate (F1) fractions, reducible or Fe–Mn oxide (F2) fractions, oxidisable or bound to organic matter (F3) fractions, and residual fractions (F4). Fraction 1 to fraction 3 of heavy metals in the soil are nonresistant fraction. Nonresistant fractions of heavy metals are labile, high mobility, and adsorbed by biota. The Distribution of heavy metal geochemical fractions in soil is influenced by physical–chemical properties of the soil. By understanding the dominant physical–chemical properties of the soil to nonresistant fractions and potential risk of soil, the potential of soil as an indicator for the heavy metals availability in bodies of water can be predicted. The aim of research was to evaluate potential of soil as an indicator for the availability of heavy metals in water bodies. The problems solved in the study were the determination of soil–physicochemical properties, determination of the geochemical fraction distribution of Cu and Zn metals in soil, determination of soil physical–chemical properties which were dominantly positively correlated with geochemical fractions of Cu and Zn in soil, and determination of potential risk of soil using Risk Assessment Code (RAC) value. Soil samples were taken from Sumber Nyolo. Sumber Nyolo is located in Ngenep, Karangploso, Malang Regency. It is an agroforestry land where there are springs which are used by local residents for several activities, such as for household activities and irrigation. The physical–chemical properties of soil determined were particle size of soil, soil pH, soil redox potential, soil organic matter, and cation exchange capacity (CEC). The geochemical fractions of heavy metals Cu and Zn was extracted from soil using the Community Bureau of Reference (BCR) modified sequential extraction by dividing it into four heavy metal fractions. Correlations of physicochemical properties of the soil to the geochemical fractions of heavy metals was analyzed using the Pearson correlation test. The potential risk of soil as a source of heavy metals for waters was evaluated using the RAC value as the percentage of F1 to the total fraction of heavy metals in the soil. The results showed that physico–chemical properties of soil in Sumber Nyolo had a neutral pH (6,9–7,4). At this pH, the oxy/hydroxide colloid in soil can be formed were Fe2O3 and FeOOH. The soil redox potential was in range from 310 mV to 335 mV, indicates that the soil is oxidized and oxic. The evaluated soil had clay particle size from 30%–55%, and the organic matter concentration from 3,67% to 4,55%. It results in the CEC value of 27,87 meq/100g–31,97 meq/100g. As results, soil of Sumber Nyolo could adsorb heavy metals by formation of complex compound with the soil organic matter and by ion exchange with soil cations. Based on percent distribution, Cu was dominant in the form of resistant fraction (F4) (57%), while Zn metal was dominant as a nonresistant fraction (F1, F2, and F3) (59%). As high mobility fraction (F1), Cu was more dominant than Zn. This means that Cu has greater mobility than Zn so that Cu metal is more easily released into water bodies. The results of the Pearson correlation test showed that pH, redox potential, and CEC were positively correlated with Cu and Zn nonresistant fraction, so that changes in these properties could cause mobilization of Cu and Zn from the soil to water body. However, based on RAC value and the soil physical–chemical properties, the soil in Sumber Nyolo has no potential in providing Cu and Zn in the water body, with RAC values of Cu and Zn were 0.13% and 0.04%, respectively. Based on the results obtained it can be concluded that by understanding physical–chemical properties of soil which are positively correlated with Cu and Zn nonresistant fraction in soil, soil can be an indicator of the availability of Cu and Zn in water body.
Other obstract
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| Item Type: | Thesis (Magister) |
|---|---|
| Identification Number: | TES/631.4/FIT/k/2019/041901342 |
| Uncontrolled Keywords: | SOIL PHYSICS—MEASUREMENT, SOIL PHYSICAL CHEMISTRY, COPPER, ZING |
| Subjects: | 600 Technology (Applied sciences) > 631 Specific techniques; apparatus, equipment materials > 631.4 Soil science |
| Divisions: | S2/S3 > Magister Kimia, Fakultas MIPA |
| Depositing User: | Budi Wahyono Wahyono |
| Date Deposited: | 23 Dec 2019 07:16 |
| Last Modified: | 04 Mar 2022 02:15 |
| URI: | http://repository.ub.ac.id/id/eprint/177321 |
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