Development of a Surface-Enhanced Raman Spectroscopy (SERS)-Based Sensor for the Long Term Monitoring of Toxic Anions
SPACE AND NAVAL WARFARE SYSTEMS CENTER PACIFIC SAN DIEGO CA
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At DoD sites, perchlorate has been used as the oxidizer component and primary ingredient in solid propellant for rockets and missiles. Perchlorate is exceedingly mobile in aqueous systems and can persist for many decades under typical ground and surface water conditions. It has been found in groundwater, drinking water, and soils, mainly in the southwestern United States, at levels ranging from 8 to 3700 ppb. Perchlorate affects the thyroid gland by blocking iodine uptake resulting in lower thyroid hormone levels. Chromate and dichromate are CrVI species that have been used in metal finishing and in metal plating operations. CrVI is a strong oxidizer and is both highly toxic and carcinogenic. Chromate and dichromate are very water soluble and have little interaction with the soil. Consequently, these pollutants are mobile, resulting in widespread groundwater contamination. Chromium contamination is present in over half of the superfund sites. Most cyanide releases into the environment come as a result of mining operations. However, in DoD, cyanide has been used in electroplating processes for silver, cadmium, gold, and copper. Cyanide is highly toxic. Exposure by eye or skin contact or ingestion can be rapidly fatal. More and more DoD sites contaminated with these anions are entering the active remediation and post remediation stages. As a result, the requirement for long-term monitoring has increased. This long-term monitoring can be for process control, for performance measurement, or for compliance purposes and can last up to 30 years. Currently monitoring is done by traditional methods of collecting aqueous samples from monitoring wells or by drilling and collecting soil samples. These samples are then sent to a laboratory for analysis. The collecting and laboratory analysis of samples is both time consuming and costly. Often the analytical results are questionable due to sampling handling procedures and biochemical interactions.
- Physical Chemistry
- Atomic and Molecular Physics and Spectroscopy
- Water Pollution and Control