Notes: Inside labs this week - density, water
Read Ch. 6 on Seawater in the text; Ch. 15 on Ocean Abuses
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Map of Chesapeake Bay - typical distribution of surface salinity

• The lines on map are like contour lines on a normal map, but reference changes in salinity, not just height. These changes in salinity are isohalines.
• Isobaths are lines of equal length that show how salinity increases or decreases with depth.
• Iso = equal
• Bath, from bathymetry = depth of water
• Chesapeake bay has several rivers flowing into it, so the isohaline is pushed further out towards the ocean

Bathymetric Profiles

• The bathymetric profile models a section of a body of water and its depth on a graph

Isohalines

• Salinity is measured in parts per thousand (ppt), ‰
• Upriver, isohalines are low, at about 1‰. Towards the mouth of the bay, salinity greatly increases to about 30‰
• The salinity of the open ocean is about 35‰
• In areas where salt and fresh water mix, the heavier seawater will be at the bottom and the freshwater will be at the top.
• This is because seawater is more dense than freshwater and slides to the bottom
• Wind has a strong influence on mixing tidal waters
• Evaporation also has an influence on the salinity of tidal waters
• In reverse estuaries, where evaporation is greater than the input of fresh water, you can get very high salinities that exceed those of the open ocean