|
<br />1 10
<br />_ 4 7 0 11
<br />---__ 31\ 5 6 0 __~---------...---nn---n
<br />;__-_._____n___..------------ 9 12
<br />04
<br />180
<br />
<br />O{)2208
<br />
<br /> 250
<br /> a:
<br /> w
<br />:;; f-- 200
<br />::>Z:J
<br /><:lOa:
<br />--'-W
<br /><(~[L 150
<br />Oa:UJ
<br />Of--:;;
<br />WZ<(
<br />>Wa: 100
<br />--'0(')
<br />OZ-
<br />UJO--'
<br />(j)O:::! 50
<br />o :;;
<br /> ~
<br />
<br />1
<br />A" ti.
<br />
<br />,
<br />,
<br />",2 -i...
<br />
<br />... " 6-
<br />" 5 . ----
<br />'~----------~--
<br />
<br />o
<br />230 220
<br />
<br />160
<br />
<br />140
<br />
<br />DISTANCE FROM MOUTH OF YAMPA RIVER, IN RIVER MILES
<br />
<br />EXPLANATION
<br />
<br />200
<br />
<br />__.__ Calcium at Yampa River site
<br />--..-- Alkalinity al Yampa River site
<br />
<br />L10
<br />
<br />UJ
<br />:;;
<br /><( OJ
<br />a:0
<br /><!JO
<br />-<(
<br />::10
<br />~UJ
<br />Z<(
<br />-a:
<br />-W
<br />i'=t:
<br />---'
<br />~a:
<br />--'w
<br />~[L
<br />--'
<br /><(
<br />
<br />
<br />---
<br />---
<br />
<br />11 12
<br />-~---------~~------------
<br />
<br />120
<br />
<br />80
<br />
<br />20
<br />
<br />o
<br />
<br />60
<br />
<br />40
<br />
<br />100
<br />
<br />D Calcium at tributary site
<br />6. Alkalinity at tributary site
<br />
<br />Note: number by symbol is site number in tables 1 and 3
<br />Figure 4, Concentrations ot calcium and alkalinity at Yampa River and main tributary sites, August 16-19, 1999,
<br />
<br />dissolved oxygen concentration that was 161 percent
<br />of saturation (relative to the concentration that would
<br />occur at equilibrium with the atmosphere)(fig, 5),
<br />Calculations using the thermodynamic-speciation
<br />program PHREEQC (Parkhurst, 1995) indicates that
<br />dissolved carbon dioxide gas (C01) (fig, 5) was under-
<br />saturated at 26 percent of the concentration that would
<br />occur at equilibrium with the atmosphere,
<br />Drever (1982) describes the formation of algae
<br />(which represents microscopic and macroscopic plant
<br />composition) by photosynthesis:
<br />
<br />106 COl + 16 N03- + HPol- + 122 H10 +
<br />18 H+ + (trace elements, energy) =
<br />CI06H16301IONI6P,(algae) + 13801,
<br />
<br />This equation explains the large pH value
<br />measured at site 3 by the uptake of dissolved C01,
<br />thus decreasing the concentration of carbonic acid
<br />(H1C03) dissolved in the water, and by direct uptake
<br />of H+ ions, which raises pH, Photosynthesis also
<br />explains the large oversaturation with dissolved
<br />oxygen, Equation 1 also shows that the formation of
<br />plant biomass depends on the availability of dissolved
<br />nitrogen and phosphorus, either of which can limit the
<br />ability of the reaction to proceed, The sample from site
<br />3 had the largest measured concentration of dissolved
<br />phosphorus (0,06 mg/L) and the second largest (after
<br />site I) measured concentrations of dissolved ammonia
<br />
<br />(I)
<br />
<br />plus organic nitrogen (0.30 mg/L) and dissolved
<br />organic carbon (5,0 mg/L) of the main-stem and tribu-
<br />tary river sites, These constituents are derived from
<br />sewage effluent, livestock waste, excretions from
<br />aquatic organisms, and other natural sources,
<br />
<br />The effects of photosynthesis on pH and
<br />dissolved oxygen concentration were attenuated at
<br />Yampa River below diversion near Hayden (site 5) by
<br />reaeration in the approximately 16,3-mile reach down-
<br />stream from the SSRWWTP and by dilution with
<br />fresher water from the Elk River (site 4), However, the
<br />relatively large pH value at site 5 (8,70) was elevated
<br />by photosynthesis, as is indicated by oversaturation
<br />with dissolved oxygen (124 percent) and undersatura-
<br />tion with COl (69 percent) (fig, 5),
<br />
<br />The Yampa River below Craig (site 6) is located
<br />about 6.2 miles downstream from the outfall from the
<br />Craig Waste Water Treatment Plant (CWWTP), This
<br />facility discharges about 1.9 ft3/s of treated sewage
<br />effluent during daylight hours (Robert Frazier, Craig
<br />Waste Water Treatment Plant, oral commun" 2000),
<br />At site 6, the effects of photosynthesis were only
<br />slightly greater than at site 5, Measured pH increased
<br />slightly to 8,80, the second largest measured value
<br />(after site 3), whereas dissolved oxygen was slightly
<br />more oversaturated (131 percent) and COl was more
<br />undersaturated (59 percent) than at site 5 (fig, 5), The
<br />relatively minor effects of photosynthesis on water
<br />quality at site 6 compared to the effects at site 3 were
<br />(at least partially) due to the larger dilution of sewage
<br />
<br />INTERPRETATION OF DATA COLLECTED FOR THIS STUDY 9
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