Determining carbon sources of eroded sediment in low order Sierra Nevada

catchments

Emma McCorkle

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Method overview

StreamSoils

Crest Bksl Dep

Forest Floor

Bank Bed

Sediment

Low

-5 -4 -3 -2 -1 0 1 2 3-29

-28

-27

-26

-25

-24

-23

3

13C and 15N High

-5 -4 -3 -2 -1 0 1 2 3-29

-28

-27

-26

-25

-24

-23

δ15N (‰) δ15N (‰)

δ13C

(‰)

High Low

4

Low

Soil depth (cm)

0 10 20 30 40 50 60

Fraction m

odern

0.6

0.7

0.8

0.9

1.0

1.1

1.2High

Soil depth (cm)

0 10 20 30 40 50 60

Fraction m

odern

0.6

0.7

0.8

0.9

1.0

1.1

1.2

Soil radiocarbon

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Sediment radiocarbon

Sediment Water Year

2008 2009 2010 2011 2012 2013 2014

Fraction m

odern

0.90

0.95

1.00

1.05

1.10

1.15

1.20

Recap

• Eroded sediment is dominated by surface material and gully erosion from established stream channels

• Deeper upland soils are more stable than shallow

• Bull has much older SOM in banks and soils than Providence– Radiocarbon bolsters stable isotope findings

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