Perchlorate is used as an oxidizer in solid propellant for rockets, missiles, and pyrotechnics. It is present in some fertilizers and is generated by other natural sources. The high solubility of perchlorate coupled with its chemical stability in water leads to expansive groundwater plumes. These same chemical properties make perchlorate contamination difficult to remediate by conventional physical-chemical water treatment methods.

SERDP and ESTCP have worked to develop an integrated program that uses a holistic approach to address the environmental impact of perchlorate. This program encompasses developing cost-effective remediation of perchlorate-contaminated groundwater, evaluating the sources of perchlorate, assessing alternatives to perchlorate as a long-term solution, and studying the toxicology of perchlorate to ecological receptors.

Remediation

SERDP and ESTCP adopted a proactive approach to managing the environmental impact of perchlorate beginning in 1998. Early research efforts focused on understanding the fate, transport, and degradation of perchlorate in the environment. These early efforts have led to commercialized cleanup technologies demonstrated at dozens of field sites across DoD. Many of the in situ remediation efforts have been described in In Situ Bioremediation of Perchlorate in Groundwater. Demonstrations under ESTCP for in situ remediation of perchlorate-contaminated groundwater have focused on investigating various design options for implementing bioremediation. In addition, the potential for monitored natural attenuation has been evaluated. Other remediation efforts have focused on wellhead treatment and vadose zone treatment.

Sources

Research supports the identification, characterization, and evaluation of natural, non-military, and military sources of perchlorate. This and other related work is summarized in Perchlorate: Environmental Occurrence, Interactions and Treatment. The demonstration and validation of forensic tools to differentiate perchlorate sources is ongoing. Such tools focus on understanding the isotopic fractionation of perchlorate and how this relates to its source.

Measurement

Research is ongoing under SERDP to develop new methods for identifying and quantifying perchlorate in the environment. Current projects are investigating enzymatic bioassays, screening-level chemical assays, and identification of functional gene biomarkers.

Ecotoxicology

SERDP has funded numerous laboratory and field studies on the effect of perchlorate on amphibians, fish, invertebrates, birds, and small mammals in support of the EPA’s ecological risk assessment. Results from these and other ecological studies have been summarized in the book Perchlorate Ecotoxicology.

Alternatives

SERDP and ESTCP are actively investigating alternatives to perchlorate for red and green colored signal flares, solid rocket propellants, and incendiary mixes and pyrotechnics. For information on these and other efforts, see Energetic Materials and Munitions under the Weapons Systems and Platforms program area.