HYDROLOGY QUESTION 4. Use your knowledge of isotope fractionation and how the is
ID: 116078 • Letter: H
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HYDROLOGY QUESTION
4. Use your knowledge of isotope fractionation and how the isotope values of precipitation changes as it moves inland. Positive values mean heavier (more 18O) and negative values mean lighter (less 18O).
a. Where are large amounts of water stored during glaciations (when there’s lots of ice)? On continents/in the middle of continents or next/on the ocean? Think about where most of the ice on Earth is today, which is basically leftover ice from the last glaciation (Ice Age) that peaked about 18,000 years ago and ended about 12,000 years ago.
b. This graph is intended to show relative temperatures. What do the red and blue colors represent in terms of temperature? (Don’t over-think this.)
c. These isotope records come from the ocean (marine) record. (They are obtained from sediment cores drilled from ships, which is way cool.) When there is a glacial time period, the sea level elevation can decrease by about 100 m. Where is all this water stored?
d. Explain why the 180 of the oceans is more positive during glacial time periods. Think about fractionation and where water is stored during a glaciation, including how much 18O is in the ice.
Land Record Traditional "glaciations" Wisconsinan Marine Record Glaciations Interglaciations 0 Illinoian 0 5 0 Illinoian 1.5 2.0 3 2 0 -2 Oxygen isotope values 180 ( units) Essentials o Copyright (c)Explanation / Answer
a. During glaciation most of the water are stored on continent as we know sea level drops during glaciation water is evaporated from the oceans and stored on the continents. in ice caps and ice sheets.
b
red------- temperature rise (high temp.)
blue -------temperature fall (low temp.
c.
because of a shift in the global hydrologic cycle: water is evaporated from the oceans and stored on the continents as large ice sheets and expanded ice caps, ice fields, and mountain glaciers.
d. 18 O Is a heavier isotope of oxygen while 16O Is lighter.During glaciation evaporation causes depletion of 16O from oceans and enrichment of 18O IN oceans thats why during glaciation O18 is positive in marine water
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