LOGO Basic Science Research Unit Remediation of heavy metals-contaminated-soil Ahmed K. Salama and Khaled A. Osman Chemistry Department, Faculty of Science, Majmaah University, KSA Abstract The present research was carried out to assess the potential possibilities of the transfer of lead and cadmium from contaminated soil to the herbal plant ryegrass. The translocation of lead and cadmium in ryegrass was compared considering root to shoot transport and redistribution of metals in the root and shoot system. The trace metal contents from root and shoot parts were determined using atomic absorption spectrometer. The results showed that the amounts of lead transferred from soil to the plant were higher than the remained amounts in soil following 60 days of treatment. In case of cadmium, the amounts of cadmium transferred from soil to plant were also higher than the remained amounts in soil following the same time interval. The soil-plant transfer index in root system was higher than that found in shoot system of ryegrass in case of lead. These values were found to be vice versa in case of cadmium. These findings indicated that ryegrass is excluder plant where it is able to exclude either lead or cadmium from soil. These plants are also called hyper-accumulators that keep contamination from spreading to other areas through the action of wind, rain and groundwater. The aim of our research was to remedy the contaminated soils with heavy metals using inexpensive technology and assess potential possibilities of the transfer of these metals from contaminated soil to excluders or hyper-accumulators plants such some herbals that keep contamination from spreading to other areas through the action of wind, rain and groundwater. Objectives 1.Badr, N., Fawzy, M. and Al-Qahtani, K. (2012), World Applied Sciences Journal 16 (9): Gisbert, C. Ros, R., de Haro, A., Walker, D.J., Pilar Bernal, M., Serrano, R., Avino, J.N. (2003), Biochem. Biophys. Res. Commun. 303: Kabata-Pendias, A. (2001): Trace elements in soils and plants, 3rd Ed. CRC Press, Boca Raton, Florida. 4.Luo, Y. Zhang, H. and Chen Tu (2012): Overview of Advances and a Look Ahead in Soil Remediation 5.Marcovecchio, J. E., Botte, S. E., Freije, R.H. (2007): Heavy metals, major metals, trace elements, In: Nollet, L.M.L. (Ed.), Handbook of water analysis, 2nd ed. CRC Press, Boca Raton, pp McGrath SP, Zhao FJ, Lombi E. (2001), Plant Soil. 232:207– Olowoyo, J.O., Okedeyi, O.O., Mkolo, N.M., Lion, G.N. and Mdakane, S.T.R. (2012), South African J. Botany, 78: Xia, H. ; Wu, L. and Tao, Q. (2003), Chin. J. Appl. Ecol. 14, 457:46. 9.Susarla, S. ; Medina, V.F. and McCutcheon, S.C. (2002), Ecol. Eng. 1818, 647:658. References Experimental method: Soil samples of a depth of 30 cm were taken, air dried, sieved to remove stones, roots and other plant materials and stored at 4 °C prior to use. Plastic pots (1L) were used for the experiment. Soil (250 g) was added for each pot. De-ionized water was subsequently added to the soil to maintain the soils at 80% of field capacity. The pots were daily irrigated with deionized water and the plant left to grow under greenhouse conditions where the temperature kept at 20°C and daily light period of 13 hrs. Metal salts of lead hydroxide carbonate and cadmium nitrate at different concentrations of 0, 100, 200, 400 and 600 µg/g soil were spiked into the pot soil. Plants were harvested after 60 days of the beginning of the experiment. Roots and shoots were left to dry at room temperature. The samples were dried at 105 °C in an oven for 24 hrs. Dried samples were ground to a powder. Five grams of each sample were placed in crucible and few drops of concentrated nitric acid were added to the solid as an ashing aid. Ashing process was carried out in a muffle furnace at 600°C. The ash was rinsed with 1M nitric acid and filtered. Spectroscopic analysis: Samples were subsequently analyzed for heavy metal contents, as dry weight basis, using an atomic absorption spectrometer (AAS). For the determination, two solutions were prepared for each sample and three separate readings were made for each solution. The means of these figures were used to calculate the concentrations. Methods and Materials Darnel Lolium temulentum Ryegrass Lolium multiflorum Some herbal plants such as ryegrass could be used as excluders or hyper-accumulators where they able to exclude heavy metals such as lead and cadmium from the contaminated soil. Thus they keep the heavy metal contamination from spreading to other areas through the action of wind, rain and groundwater. This method of soil remediation is considered easy for application, inexpensive and promising technology. Conclusions Introduction Environmental pollution has been increased because of the anthropogenic activities, use of pesticides, metals from smelting and mining, and excessive use of fertilizer (McGrath et al., 2001). Heavy metal contamination in soils can come from atmospheric fall-out, pesticide formulations, and contamination by chemical fertilizers and irrigation with water of poor quality (Marcovecchio et al, 2007). Contamination with lead can come from mining and smelting of metalliferous ores, burning of leaded gasoline, municipal sewage, industrial wastes enriched in lead, paints (Gisbert et al, 2003). Cadmium comes from anthropogenic activities, metal smelting and refining, fossil fuel burning, application of phosphate fertilizers, sewage sludge (Kabata-Pendias, 2001). They cannot be destroyed biologically but are only transformed from one oxidation state or organic complex to another pollution poses a great potential threat to the environment and human health. The use of plant species for cleaning polluted soils has gained increasing attention as an emerging effective and inexpensive technology (Susarla et al, 2002 and Xia et al, 2003). Also, it has a minimal impact on the environment (Olowoyo et al, 2012, Badr et al, 2012, Luo et al, 2012). Some excluder and hyper-accumulator plants