HR: 0800h
AN: B11B-0139    [Abstracts]
TI: Heavy Metal Contamination and Salt Efflorescence Associated With Decorative Landscaping Rocks, Las Vegas, Nevada: The Need for Regulations
AU: * Mrozek, S A
EM: mrozek@unlv.nevada.edu
AF: University of Nevada Las Vegas, Department of Geoscience, 4505 Maryland Parkway, Las Vegas, NV 89154-4010 United States
AU: Buck, B J
EM: buckb@unlv.nevada.edu
AF: University of Nevada Las Vegas, Department of Geoscience, 4505 Maryland Parkway, Las Vegas, NV 89154-4010 United States
AU: Brock, A L
EM: alb@unlv.nevada.edu
AF: University of Nevada Las Vegas, Department of Geoscience, 4505 Maryland Parkway, Las Vegas, NV 89154-4010 United States
AB: Las Vegas, Nevada is one of the fastest growing cities in the United States. Faced with water restrictions, decorative rock xeroscaping has become a very popular form of landscaping. Currently, there are no regulations controlling the geochemistry of the decorative rocks that can be used for these purposes. In this study, we examined three sites containing two different decorative rock products. The landscaping rocks, underlying soil, and surface salt crusts were analyzed to determine their mineralogy and chemistry. Methods of analysis include scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP), thin section analysis, and laser particle size analysis (LPSA). Preliminary results indicate the presence of halite (NaCl), bloedite (Na$_{2}$Mg(SO$_{4}$)$_{2}$ 4H$_{2}$O), a hydrated magnesium sulfate, and possibly copper sulfate and copper chloride mineral phases in the surface salt crusts. Both copper minerals are regarded as hazardous substances by the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA); these agencies have established minimum exposure limits for human contact with these substances. Copper sulfate and copper chloride are not naturally occurring minerals in the soils of the Las Vegas Valley, and analyses indicate that their formation may be attributed to the mineralogy of the decorative landscaping rocks. Further testing is needed to characterize this potential health hazard; however the preliminary results of this study demonstrate the need for regulations controlling the geochemistry of decorative rocks used for urban landscaping.
DE: 9350 North America
DE: 6334 Regional planning
DE: 6615 Legislation and regulation
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting