The Mono Basin Ecosystem Effects of Changing Lake Level (1987) / Chapter Skim
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3. Physical and Chemical Lake System
3. Physical and Chemical Lake System
Pages 50-68
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From page 50... ...
This stratification in turn affects the amount of nutrients and dissolved gases available to organisms in the lake. In alkaline, saline lakes such as Mono Lake, the concentration and relative proportions of the major ions (sodium, potassium, calcium, magnesium, sulfate, carbonate plus bicarbonate, and chloride)
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From page 51... ...
Changes in inputs of water or sediments caused by natural or anthropogenically induced conditions can modify morphometric features such as depth or island extent and can effect significant ecological changes. A morphometric description of Mono Lake was derived by Mason (1967)
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From page 52... ...
~ {D (D ~ {D CD to {D {D LAKE ELEVATION (ft above sea level) _ 210 Ann _ 190 180 _ 170 HIS 160 150 140 130 120 110 100 FIGURE 3.2 Morphometric parameters for Mono Basin (from data in Pelagos Corporation, 1987~.
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From page 53... ...
Exceptionally heavy snowfall and reduced diversions by the City of Los Angeles during 1982-1983 led to a large input of fresh water. The fresh water mixed only partially with the saline lake water.
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From page 54... ...
Motions of lake water such as horizontal currents, surface and internal waves, and turbulent eddies affect distributions of physical, chemical, and biological entities.
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From page 55... ...
The coefficient of evilly conductivity has been used to calculate vertical mixing rates in Mono Lake. Jellison and Melack ( 1986)
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From page 56... ...
CHEMICAL SYSTEM Chemical Composition of the Water The major components determining the chemistry of the water in Mono Lake are the major ions, major nutrients (nitrogen and phosphorus) , trace elements, and dissolved oxygen.
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From page 57... ...
Triple waters possibly form in alkaline, saline lakes in which sulfate reduction has been low over much of geologic time. Salinity as total dissolved solids (TDS)
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From page 58... ...
In the autumn, as the mixed layer deepens and brine shrimp numbers decline, the supply of ammonium from vertical mixing and entrainment became larger than the brine shrimp excretion. Trace Elements Alkaline, saline lakes generally contain comparatively large concentrations of a variety of minor elements.
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From page 59... ...
The observed chemical differences between surface and well waters indicate that calciumdominated surface waters evolve into sodium-dominated well waters owing to evaporative concentration and subsequent precipitation of calcium carbonate. Calcium-dominated surface waters have conductivities (an index of concentration)
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From page 60... ...
The chemical composition of the springs varies somewhat, but the springs are primarily dominated by sodium and carbonate plus bicarbonate (32 out of 35~. Paoha 1, Solo TT, and Dry Creek are the only spring waters in which chloride predominates over carbonate plus bicarbonate (Lee, 1969; LADWP, 1984~.
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From page 61... ...
The formation of tufa pinnacles about the orifices of sublacustrine springs is a result of inorganic precipitation and the activities of mat-forming benthic algae, which can guide the precipitation of calcium carbonate minerals and thus determine the morphology of the resulting tufa pinnacles. Because photosynthesizing algae take up CO2, they lower CO2 tensions in the microenvironment of calcium carbonate precipitation.
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From page 62... ...
Geochemical Evolution The geochemical evolution of waters in the Mono Basin to a brine of Mono Lake's present-day chemical composition can be explained in terms of the rock weathering / evaporative concentration / mineral precipitation model of lake water evolution (Garrels and MacKenzie, 1967; Eugster and Hardie, 1978~. However, the geochemical evolution of the water in Mono Lake is complicated by the presence of several volcanic hot springs that flow directly into the lake.
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From page 63... ...
The shift from calcium dominance in the stream waters to sodium dominance in the more concentrated wells and springs is presumably a consequence of the precipitation of calcite and related minerals. The chemical composition and geochemical evolution of Mono Lake is controlled primarily by mineral precipitation.
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From page 64... ...
, condensed magmatic gases, and rock-water interactions at depth (White, 1 957a; Ellis and Mahon, 1964~. Neither the moisture budget of the Mono Basin nor the geochemistry of the hot springs is known sufficiently to determine if the mineral salts from the hot springs (in excess of those contained in the original meteoric waters)
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From page 65... ...
1986. Comparative Studies of the Population Ecology and Life History Patterns of an Alkaline Salt Lake Insect: Ephyd~ra (Hyd~ropyr~cs)
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1968. Late Quaternary Stratigraphy and Geologic History of Mono Basin, Eastern California.
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From page 67... ...
1984. Background Report on Mono Basin Geology and Hydrology.
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From page 68... ...
Alkalinity dynamics in an unacidified alpine lake, Sierra Nevada, California. Limnol.
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