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Shallow ground water in areas of increasing urban development within the Upper Colorado River Basin was sampled for inorganic and organic constituents to characterize water‐quality conditions and to identify potential anthropogenic effects resulting from development. In 1997, 25 shallow monitoring wells were installed and sampled in five areas of urban development in Eagle, Grand, Gunnison, and Summit Counties, Colorado. The results of this study indicate that the shallow ground water in the study area is suitable for most uses. Nonparametric statistical methods showed that constituents and parameters measured in the shallow wells were often significantly different between the five developing urban areas. Radon concentrations exceeded the proposed USEPA maximum contaminant level at all sites. The presence of nutrients, pesticides, and volatile organic compounds indicate anthropogenic activities are affecting the shallow ground‐water quality in the study area. Nitrate as N concentrations greater than 2.0 mg/L were observed in ground water recharged between the 1980s and 1990s. Low concentrations of methylene blue active substances were detected at a few sites. Total coliform bacteria were detected at ten sites; however, E. coli was not detected. Continued monitoring is needed to assess the effects of increasing urban development on the shallow ground‐water quality in the study area.
Deicing salts applied to mountain roads during winter periods provide safe driving conditions but these salts are eventually displaced to roadside areas where they can negatively impact soils, vegetation and water resources. The aim of this study was to confirm the linkage between deicing salt applications and salt accumulation in plants and salt accumulation in soils as a function of distance from roads. We also wantedto determine whether altering the deicing salt composition would lead to a more favorable plant response. In the Mt. Charleston area of southern Nevada, NaCl was applied by the State Department of Transportation in excess of 200 tons per State Highway during the winter prior to this study. Salts sampled with depth and distance from the roads at 15 locations revealed significantly higher salinity levels (p < 0.05) at the 1 m vs. 5 and 10 m distances, with electrical conductivities as high as 37 dSm -1. In Ponderosa pine, Na and Cl concentrations were found to be elevated in needles revealing visual damage, whereas K concentrations were found to be significantly lower in damaged tissue (p < 0.05), resulting in Na/K ratios as high as 300 to 1. In a companion study we investigated the physiological response of 2 year old seedlings of aspen, Gambel oak and Woods' rose, to different salt loading rates comprised of different mixes of salts (MgSO 4 , CaCl 2 or KCl) at different %NaCl composition (100, 90, 75 and 50%). As the MgSO 4 in the salt mix increased, sulfate concentration increased in the leaves of oak (r = 0.73, p < 0.001), reflecting the shift from Cl to SO 4 availability. The % SO 4 in the leaves of oak revealed a strong linear relationship (r = 0.83 p < 0.001) with leaf weight at final harvest, as well as higher chlorophyll (spad) measurements relative to control (r = 0.89 p < 0.01) and an earlier breaking of dormancy (r = 0.65, p < 0.01), as seedlings with 2.5% SO 4 in leaves at harvest broke dormancy 10 days sooner than those oak seedlings with only 1% SO 4 in the tissue. Based on results of this study , we believe a 25% substitution of MgSO 4 would be worthy of further field evaluations as a significant decline in leaf tissue Na andCl occurred at this level, while concentrations of Ca and SO 4 increased.
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