Soils that had received successive applications of retorted oil shale (ROS) in an experiment under field conditions were used in this study, aiming to evaluate the availability of trace elements. In the batch tests, we observed that toxic elements present in the ROS are not desorbed from the matrix in significant amounts to contaminate soil and groundwater. The element Ca represents the greatest nutrient contribution, which has high mobility and ease release into the soil solution. Concerning the results obtained from the soil extracts analysis; we observed that the undesirable elements released into the extracts are not directly related to the presence of ROS in the soil samples. Comparing the behavior of soil samples with and without ROS it is possible to infer that many of the trace elements are derived from soil constituents, from previous fertilizer and pesticides applications. The study suggested that the ROS can be used as a soil conditioner for agricultural purposes without adding harmful elements to the environment.
Keywords:
soils; trace elements; retorted oil shale
