1. What affects Salinity?
Part 4

2. Precipitation 111,000 Precipitation 392,000 Evaporation 437,000
Condensation
Transpiration and
Evaporation
66,000
Evaporation
437,000
Glaciers
Groundwater
Ocean
Runoff
46,000
Figure 7.1 A simplified hydrologic cycle. Water moves—from ocean to air, onto land, to lakes and streams and groundwater, back to the sky and ocean—in a continuous cycle. The numbers indicate the approximate volumes of water in cubic kilometers per year (km3/yr). Water is also stored in the ocean, ice, groundwater, lakes and streams, and the atmosphere.
Lakes

3. Salinity Variations Open-ocean salinity is 33–38 o/oo(ppt).
Coastal areas salinity varies more widely.(Why?)
Freshwater lowers salinity or creates brackish conditions.
A greater rate of evaporation raises salinity or creates hypersaline conditions.
Salinity may vary with seasons (dry/rain).

4. Processes Affecting Salinity
Decrease salinity – add fresh water to ocean
Runoff, melting icebergs, melting sea ice
Precipitation
Increasing salinity – removing water from ocean
Sea ice formation
Evaporation

5. Variation of Salinity with Depth “Halocline Graphs”
Excess evaporation at the surface
Runoff, ice melting, less evaporation at surface
Similar salinity at depth

10. Processes Affecting Salinity