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<br />hydride-generation atomic-absorption spectroscopy.
<br />Analytical methods for selenium speciation of water
<br />samples are described in Makita and Fujii (1992).
<br />Extraction methods for selenium in bottom sediment
<br />and aquifer sediment are described in Fio and Fujii
<br />(1990).
<br />Bottom-sediment and aquifer-sediment samples
<br />for trace-element analyses were dry sieved at the labo-
<br />ratory through a 2-mm screen, The bottom-sediment
<br />samples then were sieved through a 0.0625-mm screen,
<br />and the trace-element analyses were done only on that
<br />size fraction. All samples were analyzed for selenium,
<br />uranium, other trace elements, total carbon, and
<br />organic carbon using methods described by Stewan
<br />and others (1992).
<br />Selected sediment-core and bedrock samples
<br />were analyzed for semiquantitative data on bulk and
<br />clay mineralogy using X-ray diffraction (XRD) and for
<br />panicle morphology and gross element composition
<br />using scanning-electron microscopy (SEM), In addi-
<br />tion, a few of the filters used for filtering ground-water
<br />samples were saved, dried, and analyzed by XRD and
<br />SEM to characterize particulate phases in the ground
<br />water.
<br />All biological samples were sent to contract lab-
<br />oratories through the FWS Patuxent Analytical Control
<br />Facility (PACFl in Patuxent, Maryland. Except for five
<br />samples, analyses for trace elements were done at the
<br />Environmental Trace Substances Research Center in
<br />Columbia, Missouri. The other five samples were ana-
<br />lyzed at Research Triangle Institute, North Carolina.
<br />Samples were analyzed for selenium and selected trace
<br />elements using inductively coupled argon-plasma
<br />atomic-absorption spectrometry after complete diges-
<br />tion of the sample in strong acids. Analyses for arsenic
<br />and selenium were done using hydride-generation
<br />atomic absorption, and analyses for mercury were done
<br />by f1ameless cold-vapor atomic absorption, Analyses
<br />for organochlorine pesticides were done at the Missis-
<br />sippi State Chemical Laboratory, Mississippi State
<br />University, Mississippi, and analyses for polycyclic
<br />aromatic hydrocarbons were done at the Geochemical
<br />and Environmental Research Group, Texas A and M
<br />University, Texas. All analytical data were reviewed
<br />by the PACE Quality-control procedures done by the
<br />PACF included sample spikes, duplicates, and blanks.
<br />
<br />DESCRIPTION AND ORGANIZATION OF
<br />DATA
<br />
<br />The hydrologic and biological data presented in
<br />this report are in tables 4-39 in the "Hydrologic and
<br />Biological Data" section at the back of this report.
<br />Onsite measuremenlS and chemical analyses of sur-
<br />
<br />face-water samples are listed in tables 4 through 8.
<br />Data for the Uncompahgre Project area are listed in
<br />table 4, which includes data for all sites in the
<br />Uncompahgre River Basin and in the lower Gunnison
<br />River Basin upstream from Escalante Creek (at site
<br />GUNS on pI. I). Onsite measurements and chemical
<br />data for sites in the Grand Valley, excluding the sites on
<br />the Colorado River and Gunnison River are listed in
<br />table 5, On site measurements and chemical data for
<br />sites on the Colorado River, Plateau Creek, and the
<br />Gunnison River at Whitewater are listed in table 6.
<br />Some of the chemical data in tables 4 and 6 for sites on
<br />the Uncompahgre, Gunnison. and Colorado Rivers that
<br />are at USGS gaging stations were collected for other
<br />programs of the USGS during 1991 and 1992. Concen-
<br />trations of stable isotopes of hydrogen and oxygen in
<br />surface-water samples are listed in table 7. The insec.
<br />ticide results for the samples collected in 1991 in the
<br />Grand Valley are listed in table 8,
<br />Ranges of specific-conductance and dissolved-
<br />oxygen measurements for selected wells in the
<br />Uncompahgre ProjecI area are shown in figures 2 and
<br />3. Ranges of specific conductance and dissolved-
<br />oxygen measurements for selected wells in the Grand
<br />Valley are shown in figures 4 through 7. Daily records
<br />of water levels and daily specific conductance in
<br />well 143NO in the Grand Valley are shown in figure 8.
<br />Onsite measurements and selected chemical data for
<br />ground-water sites where water-quality samples were
<br />collected are listed in tables 9 through 12. The onsite
<br />measurements are in table 9, and chemical analyses for
<br />major constituents, nitrogen species, and dissolved-
<br />organic carbon are listed in table 10. Trace-element
<br />data are listed in table II, and stable-isotope data are
<br />listed in table 12.
<br />
<br />The BOR collected extensive water-level and
<br />dissolved-solids data in the Grand Valley in the 1970's
<br />and 1980's for hydrosalinity studies, Selected histori-
<br />cal water-level and dissolved-solids data for two wells
<br />are shown in figure 9 (Jack Cunningham, U.S. Bureau
<br />of Reclamation, wrillen commun., 1992).
<br />
<br />Chemical data for bottom-sediment samples, a
<br />salt-cnlst sample, and a soil sample collected during
<br />1992 in the Uncompahgre Project area and in the Grand
<br />Valley are listed in tables 13 and 14. The analytical
<br />data for trace elements are listed in table 13, and the
<br />analytical data for major constituents, total carbon. and
<br />organic carbon are listed in table 14.
<br />Trace-element concentrations in bedrock and
<br />aquifer-sediment samples collected in the Uncompah-
<br />gre Project area and in the Grand Valley are listed in
<br />table IS, and the major-constituent, total-carbon, and
<br />organic-carbon data for the same group of samples are
<br />listed in table 16. Semiquantitative data on bulk and
<br />
<br />6 Physical, Chemical, and Biological Data tor Detailed Study ot Irrigation Drainage In the Uncompahgre Project Area and
<br />In the Grand Valley, West-central Colorado, 1991-92
<br />
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