The immobilization of heavy metals by a tropical andepts treated with lime and organic composts
1997
Salam, A.K. | Djuniwati, S. | Sarno | Sriyani, N. | Novpriansyah, H. | Septiana, A. | Widiarini, D.P.
Heavy metal solubility in soils has been reported to be altered by an addition of lime and/or organic materials. This research was intended to evaluate the effects of some lime or organic materials on the extractability of heavy metals in an andic soil (Andepts), which is well-known to have an extremely high adsorption capacity, with respect to organic compounds and phosphate. Soil sample, collected from South Lampung, Indonesia, lime materials comprising CaCO3, Ca(OH)2, and CaMg(CO3)2, and composts of plant leaf ("alang-alang", corn, cassava, and soybean) were used. The soil sample (air dry, 2-mm-sieved) was treated independently with lime (at a level to increase its pH about 2 unit) or with organic compost (at 10 mg/ha. The mixture was spiked with a standard solution containing 10 mg/kg Cu, Cd, Mn, and Zn and incubated for 8 weeks at the soils' field moisture capacity. The heavy metals were extracted with DTPA and measured with flame AAS. The results showed that the extractable heavy metals in limed soil (except Cd) in general were greater than those in unlimed soils, probably due to the increased of active soluble organic material concentration complexed with heavy metals in increasing soil pH. The organic composts generally did not affect the extractability of heavy metals except Mn, that increased with compost addition in samples not spiked with heavy metals, particularly in samples treated with soybean compost. The insignificant difference in the extractability of heavy metals between the spiked and unspiked soil samples and the lower Mn extractability in spiked soil samples suggested that the Andepts was a good absorber for heavy metals, expect for Cd. The majority of Cd added was recovered bith in lime- or in compost-treated soils. Based on the percent recovery values, the preference of the soil toward the heavy metals followed the sequence of Mn Zn Cu Cd
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