An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves...
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![Page 1: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/1.jpg)
An undisturbed sediment core containing varves from the deposition zone of a deep lake
The varves can be used to calculate dates along the core profile
![Page 2: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/2.jpg)
Paleolimnology--Pollen stratigraphy in lake sediment cores
![Page 3: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/3.jpg)
Cores can be dated with radioisotopes
137Cs (half-life 30 yr) is found in fallout from bomb tests
The most commonly used isotope is 210Pb, half-life 22 yr
![Page 4: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/4.jpg)
![Page 5: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/5.jpg)
210Pb
218Po
222Rn
226Ra
238U
The Uranium 238 decay series
![Page 6: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/6.jpg)
![Page 7: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/7.jpg)
The littoral zone, what determines its outer boundary?
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The transparency of lake water is measured by its extinction coeficient
The extinction coefficient k increases with:
•the concentration of organic matter (colour) of the water
•the amount of suspended mattereg, phytoplankton, fine suspended particles, eg
clay
![Page 9: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/9.jpg)
Light extinction --Light enters from above and its intensity (I) is sharply attenuated with depth (z)—absorption by water or solute molecules or scattered by particles
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Section 10.6
Page 144 in text
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![Page 10: An undisturbed sediment core containing varves from the deposition zone of a deep lake The varves can be used to calculate dates along the core profile.](https://reader036.fdocuments.net/reader036/viewer/2022062516/56649d5e5503460f94a3dd17/html5/thumbnails/10.jpg)
In general Photosynthesis exceeds respiration above the 1% light level and rooted plants can grow down to about the 10% light level
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