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<br />
<br />Salinity Increases in the Navajo Aquifer in' Southeastern Utah
<br />
<br />TABLE 1. Chemical Data from Ground. and Surface-Water Samples and Well-Depth Data
<br />Collected in and Adjacent to the Study Area (cont'd,)
<br />
<br />[Field site location and explanation shown in Figure 1; dim/s, degrees/minutes/seconds; g/cm3,' grams per cubic centimeter;
<br />mglkg, mil1i~ms per kilogram; permil, per thousand; -, not determined; <, less than; ibIs; feet below land surface]
<br />
<br />Well depth; dashes indica1;e well log data are absent and well is presumed to yield water from Navajo aquifer; a depth exceeding 5,000 feet
<br />indicates original depth of oil test hole - well plugged back to Navajo aquifer; >, minimum plumbed depth, no well logs available.'
<br />
<br />Del Del Wen
<br />Oxygen-IS Deuterium Depth
<br />(permil) (permil) (ibis)
<br />
<br />N
<br />~
<br />(0
<br />~
<br />
<br />Field
<br />Site
<br />
<br />Lon~tude
<br />(d/p>Is)
<br />
<br />Bromide
<br />(mgikg)
<br />
<br />Chloride
<br />(mgikg)
<br />
<br />Latitude
<br />(d/mls)
<br />
<br />Density
<br />(glcm3)
<br />
<br /> Alluvial Aquifer
<br />A2 371301 lOe1157 0,995 0,04 0.008 16 -13.15 -96.0 <100
<br /> Oil-Field Brine
<br />PRD5 371120 lOel643 1.047 190 10.5 46,000 -7.58 -72,3
<br />PRD4 371254 10~1744 1.058 260 16,1 45,000 -5,60 -68,5
<br />PRD2 371538 10$1206 1.051 260 17.1 42,000 -7.51 -72,1
<br />PRD3 371747 1090453 1.116 360 42,1 99,000 2.19 -42,0
<br />PRDl 371752 1091544 1.054 270 16,1 46,000 -K70 -79.0
<br />M-44 3,080 241,000
<br />M_64 1,150 259,106
<br />M_74 1,612 249,300
<br />M_1l4 3,000 45,000
<br /> Non-Oil-Field Brine
<br />4E5 72 127,100
<br />BE6 73 129,300
<br />12E5 74 126,250
<br />
<br />lWater flows outside of casing. _
<br />2Water flows from around pt~ged and abandoned marker. .
<br />3Water flows from open casilW below land surface.
<br />4Data collected from sites north of the study area near Moab, Utah, in the Paradox Basin. Data compiled from Mayhew and- Heyt-
<br />mum (1965), ,
<br />5Dats collected from sites northeast of the study area in Paradox Valley, Colorado. Data compiled from Rbsenbauer et al. (1992).
<br />
<br />RESULTS AND DISCUSSION
<br />
<br />Bromide- To-Chloride Ril-tios
<br />
<br />Bromide-to-chloridll weight ratios were used to
<br />determine different conservative chemical signatures
<br />of the OFB and non-OrB end-member waters. These
<br />constituents have been: used successfully in previous
<br />ground-water salinity.studies to differentiate OFB
<br />from non-OFB waters (Whittemore, 1988; Richter and
<br />KreitJer, 1991) and haye two useful characteristics.
<br />Neither constituent gen:eralIy participates in chemical
<br />reactions in non-brine;systems (Whittemore, 1988).
<br />Bromide is enriched ip organic materials (Whitte-
<br />more, 1988; Maida, 19$9), possibly providing consid-
<br />erable differences in brpmide concentrations between
<br />samples ofOFB (enrich.d with organic materials) and
<br />non-OFB (limited in organic materials) waters.
<br />Bromide and chlorid~ concentrations in water sam-
<br />ples collected from thlo Navajo aquifer, San Juan
<br />
<br />River, adjacent allrtvium, and Paradox Formation
<br />were compared with the bromide-to-chloride ratio of
<br />modern ocean water of 0.003.44 (Figure 4). In geIleral,
<br />samples from the San Juan River and a well'complet-
<br />ed in the shallow alluvium plot close to the ratio of
<br />modern ocean water, suggesting an atmospheric bro-
<br />mide source, primarily' as sea spray. Water samples
<br />from the Navajo aquifer with a chloride concentration
<br />less than or equal to 60 milligrams per kilogram
<br />(mg!kg), in general, plot close to the ratio of modem
<br />. ocean water (mean = 0,0037, n = 13); however, as the
<br />chloride concentration increases, most of the samples
<br />plot below the ocean water ratio with a mean bro-
<br />mide-to-chloride ratio of 0.0014 (n = 35). Non-OFB
<br />samples become depleted in bromide relativ6 to mod-
<br />ern ocean water, possibly indicating a limited amount
<br />of organic matter and relatively small bromide con-
<br />centrationsin chloride minerals. According to Whitte-
<br />more (1988), halite formed during the latter stages of
<br />ocean-water evaporation has a bromide-to.chloride
<br />
<br />
<br />
<br />1125
<br />
<br />WATER RESOURCES BULLETIN
<br />
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