Evaluation of lead availability in amended soils monitored over a long-term time period

Two different soil amendment processes were evaluated for reducing lead availability from a contaminated soil at a demonstration study site, to reduce potential public health and environmental concerns. A limited variety of in vitro laboratory "availability" tests (relative bioaccessible and environmental mobility) were performed to determine if the available lead in the contaminated soil would be less available after in situ soil amendment (chemical treatment). The relative bioaccessibility results were evaluated in both a short-term period (within 24 h after treatment) and over a long-term time period (quarterly basis for 5 years). Reduction in relative bioaccessibility was noted for one of the treatments immediately after treatment; however, both treatments indicated a significant upward trend in bioaccessibility values over a 5-year time period after treatment. The comparison between the treated units and the control units indicated that the long-term effectiveness of the treatment processes could not be demonstrated.