Slide #1.

Salinity of Lakes, Rivers, and Reservoirs
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Slide #2.

Saline vs. Marine • Marine water mainly sodium chloride 35%o • Saline waters vary in dominant ions • Surface waters range from almost pure water to several times the ionic strength of sea water
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Slide #3.

Saline lake Classification Name Concentration range Subsaline 0.5-3‰ Hyposaline 3-20‰ Mesosaline 20-50‰ Hypersaline >50‰
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Slide #4.

Some Saline Inland Waters Name Don Juan Pond Lake Vanda Lake Assal Dead Sea Great Salt Lake Location Antarctica Antarctica Djibouti (Affar) Jordan/Israel Utah, USA Salinity >400‰ <400‰ 348‰ 337‰ 50-270‰ Mono Lake California, USA 50-99‰ Other Never freezes Meromictic -155m -378m Remnant of Lake Bonneville Highly productive
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Slide #5.

• Don Juan Pond (~400‰) • Lake Vanda –deep meromictic lake
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Slide #6.

Lake Assal -Djibouti • Crater lake 155m below sea level. • Salinity 348 ‰
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Slide #7.

Dead Sea 337‰ and 378m below sea level
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Slide #8.

Great Salt Lake
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Slide #9.

Mono Lake
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Slide #10.

Major Cations of Surface Waters Hard Water • Calcium • Magnesium • Sodium • Potassium Soft Water • Calcium • Sodium • Magnesium • Potassium
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Slide #11.

Major Anions of Surface Waters comment on Tables 10-1, 10-3, & 10-4 Hard Water • Bicarbonate • Carbonate • Sulfate • Chloride Soft Water • Chloride • Sulfate • Carbonate
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Slide #13.

Salinity due to: • Substrate (soil, geology) • Total precipitation • Ratio of precipitation to evaporation Comment on Table 10-2
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Slide #14.

Aral Sea
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Slide #15.

Saline lakes form when • Outflow is restricted • Evaporation rate exceeds inflow or outflow • Inflow equals evaporation plus outflow
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Slide #16.

Saline Lakes are different from hard water lakes • Mainly sodium chloride
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Slide #17.

• Conductivity • Specific conductance
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Slide #18.

Sources of ions • Direct weathering of rock (e.g. sodium chloride) • ReDox reactions involving iron, manganese, sulfur, nitrogen, phosphorus, and carbon • H+ from carbonic acid, acid rain, humic acids • Influence of groundwater
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Slide #20.

Precipitation as a source of ions • Wind-borne salt • Dust • Acid rain
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Slide #21.

Calcium • Essential element for most living things • Soft-water: low Ca • Hard-water: high Ca • Photosynthesis causes decline of Ca • Metabolism causes increase of Ca Interpret Figures 10-3, 10-4, & 10-5
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Slide #22.

Ca & conductivity in Lawrence Lake
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Slide #23.

Ca in Wintergreen Lake
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Slide #24.

Magnesium • Necessary for chlorophyll • Unlike Ca, very soluble and does not easily precipitate Interpret Figure 10-6 and compare with Figure 10-3
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Slide #25.

Magnesium in Lawrence Lake
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Slide #26.

• Sodium, potassium and other minor cations also very soluble
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Slide #27.

Sodium concentrations
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Slide #28.

Monovalent: Divalent Cation Ratios • M:D < 1.5 favors diatoms • M:D > 1.5 favors desmids
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Slide #29.

Anions, especially halides in surface waters • Examine Figure 10-8, chloride concentrations in Little Crooked Lake
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Slide #30.

Chloride in Little Crooked Lake
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Slide #31.

Origins of freshwater biota • Bacteria: homiosmotic • Protists: variable, most from marine forms • Plants: from terrestrial groups, few saline plants (e.g. Spartina). Some like Nymphaea primitive freshwater aquatic forms • Animals: Many from marine environments; however, insects from terrestrial groups
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