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Salinity of Lakes, Rivers, and Reservoirs. Saline vs. Marine Marine water mainly sodium chloride 35% o Saline waters vary in dominant ions Surface waters.

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Presentation on theme: "Salinity of Lakes, Rivers, and Reservoirs. Saline vs. Marine Marine water mainly sodium chloride 35% o Saline waters vary in dominant ions Surface waters."— Presentation transcript:

1 Salinity of Lakes, Rivers, and Reservoirs

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

3 Saline lake Classification NameConcentration range Subsaline0.5-3‰ Hyposaline3-20‰ Mesosaline20-50‰ Hypersaline>50‰

4 Some Saline Inland Waters NameLocationSalinityOther Don Juan PondAntarctica>400‰Never freezes Lake VandaAntarctica<400‰Meromictic Lake AssalDjibouti (Affar)348‰-155m Dead SeaJordan/Israel337‰-378m Great Salt LakeUtah, USA50-270‰Remnant of Lake Bonneville Mono LakeCalifornia, USA50-99‰Highly productive

5 Don Juan Pond (~400‰) Lake Vanda –deep meromictic lake

6 Lake Assal -Djibouti Crater lake 155m below sea level. Salinity 348 ‰

7 Dead Sea 337‰ and 378m below sea level

8 Great Salt Lake

9 Mono Lake

10 Major Cations of Surface Waters Hard Water Calcium Magnesium Sodium Potassium Soft Water Calcium Sodium Magnesium Potassium

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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13 Salinity due to: Substrate (soil, geology) Total precipitation Ratio of precipitation to evaporation Comment on Table 10-2

14 Aral Sea

15 Saline lakes form when Outflow is restricted Evaporation rate exceeds inflow or outflow Inflow equals evaporation plus outflow

16 Saline Lakes are different from hard water lakes Mainly sodium chloride

17 Conductivity Specific conductance

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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20 Precipitation as a source of ions Wind-borne salt Dust Acid rain

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

22 Ca & conductivity in Lawrence Lake

23 Ca in Wintergreen Lake

24 Magnesium Necessary for chlorophyll Unlike Ca, very soluble and does not easily precipitate Interpret Figure 10-6 and compare with Figure 10-3

25 Magnesium in Lawrence Lake

26 Sodium, potassium and other minor cations also very soluble

27 Sodium concentrations

28 Monovalent: Divalent Cation Ratios M:D < 1.5 favors diatoms M:D > 1.5 favors desmids

29 Anions, especially halides in surface waters Examine Figure 10-8, chloride concentrations in Little Crooked Lake

30 Chloride in Little Crooked Lake

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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