Rainfall Lysimeter Evaluation of Leachability and Surface Transport of Heavy Metals From Six Soils With and Without Phosphate Amendment

Abstract

The addition of phosphate materials such as hydroxyapatite (HAP) has been suggested and used for treatment and stabilization of lead-contaminated soils. HAP has been used at some small arms firing ranges (SAFRs) to contain the lead in berm soils onsite. The two primary pathways for lead migration from the sites are via leachate production and surface runoff water from rainfall. The focus of this study is the in situ treatment of various representative berm soils with HAP using large berm lysimeters under simulated field conditions. Six soils were enriched with lead by firing military rounds of M855, 5.56-mm, lead/copper/antimony bullets into the soils. The six lead-enriched soils were treated with HAP amendment and six of the same enriched soils were tested without HAP treatment. The soils were placed in the lysimeters and subjected to rainfall over a period of time. Leachate and runoff samples were collected. The effectiveness of the HAP treatment was determined by the amount of lead and other metals lost from the treated soils as compared to the soils without any treatment.