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Geospatially-networked Sensors for Heavy Metal Detection in Surface Water and Soil


OBJECTIVE: Development of small, portable geospatially-enabled mesh-networked sensors for dynamic detection of heavy metals in water and soil. The objective is to develop sensors that are capable of being integrated into existing Engineering Research and Development Center (ERDC) sensor network specifications in order to detect, monitor and report concentrations of heavy metals in surface waters and soils. Elements of interest include, but are not limited to: lead, arsenic, chromium, mercury, and cadmium. Surface waters represent the main source water for deployed personnel and heavy metals are not completely removed by filtration treatment technologies currently in use by the Army. Such technology is also needed for environmental monitoring and water quality analysis. Soils, on the other hand, are the major sink of heavy metals released into the environment by anthropogenic activities and the presence of such contaminants poses risks to human health through contamination of ground water or reducing land usability for agricultural production. DESCRIPTION: There is a critical need to assess the water and soil conditions of operating bases for soldier safety and restoration efforts. Assessment of heavy metal concentrations at potential operating sites would help in determining feasibility of proposed operation areas, limit soldier exposure to heavy metal toxins, and provide an ecological record of the conditions before US activities. The post-use assessment of a site would provide financial and political insurance from costly remediation of preexisting conditions, political fallout over inappropriate US land usage and a record physical of the environment after US usage. The current techniques of heavy metal detection include Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma-Mass Spectrometry (ICPMS) however, such methods require costly equipment which is not practical to use in the field, also produce gaseous waste products that can be difficult to dispose of, and can only be operated by personnel having specialized training. Currently, electrochemical methods are showing promise for heavy metal detection, but have been performed in ideal laboratory conditions and in isolation from complex matrices. X-Ray fluorescence is highly effective and portable but requires expensive sealed radiation sources and large energy requirements. A need exists for an inexpensive and deployable sensor to assess heavy metal conditions from soil and water samples. Such a device could have automated sampling or require a minimal of human training for loading of samples. The target sensitivity would be determining concentrations of less than 1 part per million (ppm) and have very low to no reagent requirements on a daily basis. Examples could be usage with only a weekly re-supply of liquid, chemical, or battery consumables. The desired sensor will be able to be integrated into a larger, GPS-enabled wireless reporting system of meshed networked sensors for automated sample data retrieval and geo-spatial mapping. PHASE I: Construct a functional concept design capable of detecting 5 simultaneous targets from the list above, at 80% of required limit in under 10 minutes. Design should include plans and flexibility for mesh network integration, sample preparation, and military ruggedization. PHASE II: Develop a prototype device which integrates into an existing mesh network and can detect 5 simultaneous targets at concentrations of less than 1 part per million (ppm). Provide calibration data for single and multiple targets, power usage information, and consumables that can withstand long shelve lives, temperature extremes, and rough handling. PHASE III: The intended device has application beyond military use and can be applied for environmental monitoring, remote site monitoring where with limited man power and/or communications, and for disaster response. REFERENCES: 1. Ruana, R.A. and Okieiman, F.E., 2011. Heavy metals in contaminated soils: a review of sources, chemistry, risks, and best available strategies for remediation. ISRN Ecology. 2. TG 230 Environmental Health Risk Assessment and Chemical Exposure Guidelines for Deployed Military Personnel, June 2010. 3. Turdean, G.L., 2011. Design and development of biosensors for detection of heavy metal toxicity. International Journal of Electrochemistry. 4. Grieshaber,D., MacKenzie, R., Voros, J., and Reimhult, E., 2008. Electrochemical biosensors - sensor principles and architectures. Sensors (8): 1400 - 1458.
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