DNA-labeled silica microspheres for groundwater tracing and colloid transport studies
- Oak Ridge National Lab., TN (United States)
Our understanding of transport dynamics within fractured systems is limited by inadequate quantitative information about the geometry and interconnectedness of the fracture network and the means to determine these properties. Currently, groundwater tracers represent our best tool for quantitative determination of transport, although a large number of tracers that behave identically is required. We developed and tested a new type of colloidal tracer for groundwater investigations that have identical chemical and physical properties but are uniquely labeled. This novel tracer consists of silica microspheres to which DNA segments have been attached. The microspheres are coated with DNA by chemical modification of the silica surface and attachment at the 5{prime} end through an amine linkage. This technique provides an almost unlimited number of uniquely tagged yet physically and chemically identical colloidal-sized (0.5 mm) tracers. The DNA-labeled microspheres have been tested in packed columns of silica sand and iron coated silica sand. DNA hybridization techniques are utilized to detect each unique DNA tag. Quantitation of signal is possible using a DNA standard. The microspheres have been used in field studies designed to estimate the flow velocity of water through fractures and to delineate fracture interconnectivity during pumping tests in fractured shales. While others have successfully attached DNA fragments to clay particles, our approach is unique in that it ensures physical and chemical uniformity as well as stronger bonds due to the covalent attachment. This is not true for clay particles, which vary in size and composition and can lose more of the DNA label in the system due to wreak attachment by adsorption. Other types of colloidal tracers having uniform properties (e.g., fluorescent microspheres) do not provide the flexibility that DNA-tagged tracers do because of the limited number of varieties available.
- OSTI ID:
- 437344
- Report Number(s):
- CONF-960807-; ISSN 0270-3009; TRN: 97:000878-0031
- Journal Information:
- National Meeting - American Chemical Society, Division of Environmental Chemistry, Vol. 36, Issue 2; Conference: 212. national meeting of the American Chemical Society (ACS), Orlando, FL (United States), 25-30 Aug 1996; Other Information: PBD: 1996
- Country of Publication:
- United States
- Language:
- English
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