Oil shale ash contains mineral ingredients of agricultural importance and could be used for treatment of soils. However, the ash contains several hazardous ingredients, i.e. toxic trace metals which could be mobile and create environmental concerns. Beneficial use of the oil shale ash in agriculture and forestry requires better knowledge of leaching characteristics of soil-ash systems. In this study two different ash samples have been added to two types of soil, particularly Rendzic Leptosol and Podzolic Gleysols, in order to investigate the leaching characteristics of soil/ash mixtures using the traditional leaching scheme and a scheme modified by pretreatment (incubation) of solid in wet conditions. The pH, conductivity and concentration of Cd, Pb, Cr, Zn and Ni in leachates are determined. The results revealed that transport of hazard components to the water phase was highly dependent on the type of soil and ash and leaching method used. Throughout the experiment, concentrations of heavy metals in leachates of any combination of soil and fly ash are low. The most mobile metals are found to be nickel, zinc and chromium. Application of oil shale ash to soil might increase mobile fraction of Ni in soil.
For the safe recycling of oil shale wastes in agriculture, it is recommended to take into account the leaching behavior of trace elements as ingredients in combustion ash. 1. Jala, S., Goyal, D. Fly ash as a soil ameliorant for improving crop production - a review // Bioresource Technol. 2006. Vol. 97, No. 9. P. 1136–1147.
doi:10.1016/j.biortech.2004.09.004
2. Jankowski, J., Ward, C. R., French, D., Groves, S. Mobility of trace elements from selected Australian fly ashes and its potential impact on aquatic ecosystems // Fuel. 2006. Vol. 85, No. 2. P. 243–256.
3. Kikas, V. H. Mineral matter of kukersite oil shale and its utilization // Oil Shale. 1988. Vol. 5, No. 1. P. 15–27 [in Russian].
4. Turbas, E. Use of oil-shale ashes as a lime fertilizer in Estonia // Oil Shale. 1992. Vol. 9, No. 4. P. 301–309 [in Russian].
5. Gangloff, W. J., Ghodrati, M., Sims, J. T., Vasilas, B. L. Field study: influence of fly ash on leachate composition in an excessively drained soil // J. Environ. Qual. 1997. Vol. 26. P. 714–723.
doi:10.2134/jeq1997.00472425002600030017x
6. Clark, R. B., Ritchey, K. D., Baligar, V. C. Benefits and constraints for use of FGD products on agricultural land // Fuel. 2001. Vol. 80, No. 6. P. 821–828.
7. Sajawan, K. S., Paramasivam, S., Alva, A. K., Adriano, D. C., Hooda, P. S. Assessing the feasibility of land application of fly ash, sewage sludge and their mixtures // Adv. Environ. Res. 2003. Vol. 8, No. 1. P. 77–91.
doi:10.1016/S1093-0191(02)00137-5
8. Saether, O. M., Banks, D., Kirso, U., Bityukova, L., Sorlie, J.-E. The chemistry and mineralogy of waste from retorting and combustion of oil shale // In: Energy, Waste, and the Environment: a Geochemical Perspective / R. Giere, P. Stille (eds.). London: Geological Society, Special Publication, 2004. P. 263–284.
9. Pets, L., Vaganov, P., Knoth, J., Haldna, Ü., Shwenke, H.,Schnier, C., Juga, R. Microelements in oil-shale ash of the Baltic Thermoelectric Power Plant // Oil Shale. 1985. Vol. 2, No. 4. P. 379–390 [in Russian].
10. Häsänen, E., Aunela-Tapola, L., Kinnunen, V., Larjava, K., Mehtonen, A., Salmikangas, T., Leskelä, J., Loosaar, J. Emission factors and annual emissions of bulk and trace elements from oil shale fueled power plants // Sci.Total Environ. 1997. Vol. 198, No. 1. P. 1–12.
doi:10.1016/S0048-9697(97)05432-6
11. Adriano D. C. Trace Elements in Terrestrial Environments. 2nd ed. – New York: Springer-Verlag, 2001.
12. Wright, R. J., Codling, E. E., Stuczynski, T., Siddaramappa, R. Influence of soil-applied coal combustion by-products on growth and elemental composition of annual ryegrass // Environ. Geochem. Hlth. 1998. Vol. 20, No. 1. P. 11–18.
13. Tripathi, R. D., Vajpayee, P., Singh, N., Rai, U. N., Kumar, A., Ali, M. B., Kumar, B. Yunus, M. Efficacy of various amendments for amelioration of fly-ash toxicity: growth performance and metal composition of Cassia siamea Lamk // Chemosphere. 2004. Vol. 54, No. 11. P. 1581–1588.
14. Kirso, U., Irha, N., Reinik, J., Urb, G., Laja, M. The role of laboratory and field leaching tests in hazard identification for solid materials // ATLA. 2007. Vol. 35, No. 1. P. 119–122.
15. Ram, L., Srivastava, N. K., Tripathi, R. S., Thakur, S. K., Sinha, A. K., Jha, S. K., Masto, R. E., Mitra, S. Leaching behavior of lignite fly ash with shake and column tests // Environ. Geol. 2007. Vol. 51, No. 7. P. 1119–1132.
doi:10.1007/s00254-006-0403-1
16. Raave, H., Kapak, S., Orupõld, K. Phytotoxicity of oil shale semi-coke and its aqueous extracts: a study by seed germination bioassay // Oil Shale. 2007. Vol. 24, No 1. P. 59–72.
17. Dellantonio, A., Fitz, W. J., Custovic, H., Repmann, F., Schneider, B. U., Grünewald, H., Gruber, V., Zgorelec, Z., Zerem, N., Carter, C., Marcovic, M., Puschenreiter, M., Wenzel, W. W. Environmental risks of farmed and barren alkaline coal ash landfills in Tuzla, Bosnia and Herzegovina // Environ. Pollut. 2008. Vol. 153, No. 3. P. 677–686.
doi:10.1016/j.envpol.2007.08.032
18. Uibu, M., Uus, M., Kuusik, R. CO2 mineral sequestration in oil-shale wastes from Estonian power production // Environ. Manage. 2009. Vol. 90, No. 2. P. 1253–1260.
doi:10.1016/j.jenvman.2008.07.012
19. Riehl, A., Elsass, F., Duplay, J., Huber, F., Trautmann, M. Changes in soil properties in a fluvisol (calcaric) amended with coal fly ash // Geoderma. 2010. Vol. 155, No. 1–2. P. 67–74.
20. Petersell, V., Mõttus, V., Täht, K., Unt, L. Bulletin of the Geochemical Monitoring of Soil 1992 – 1994. – Geological Survey of Estonia, Department of Environmental Geology. Tallinn, 1996.
21. Kuusik, R, Uibu, M, Kirsimäe, K. Characterization of oil shale ashes formed at industrial-scale CFBC boilers // Oil Shale. 2005. Vol. 22, No. 4S. P. 407–420.
22. Pathan, S. M., Aylmore, L. A. G., Colmer, T. D. Properties of several fly ash materials in relation to use as soil amendments // J. Environ. Qual. 2003. Vol. 32, No. 2. P. 687–693.
doi:10.2134/jeq2003.0687
23. Trace Elements in Natural Waters / B. Salbu, E. Steinnes (eds.). – Boca Raton, FL: CRC Press, 1995.
24. Irha, N., Steinnes, E., Kirso, U., Petersell, V. Mobility of Cd, Pb, Cu, and Cr in some Estonian soil types // Est. J. Earth Sci. 2009. Vol. 58, No. 3. P. 209–214.
25. Petersell, V., Ressar, H., Carlsson, M., Mõttus, V., Enel, M., Mardla, A., Täht, K. The Geochemical Atlas of the Humus Horizon of Estonian Soil. – Tallinn – Uppsala, 1997. 75 p.
26. Stark, J., Redente, E. Trace element and salt movement in retorted oil shale disposal sites // J. Environ. Qual. 1986. Vol. 15. P. 282–288.
doi:10.2134/jeq1986.00472425001500030016x
doi:10.1016/j.apgeochem.2008.02.001
