using chemistry to determine sediment source in white clay creek white clay wild and scenic...

Using Chemistry to Determine Sediment Source in White Clay Creek

White Clay Wild and Scenic Watershed SummitSeptember 25, 2012

Dr. Diana L. Karwan

University of Delaware Department of Geological SciencesStroud Water Research Center

Photo: Marissa Morton

Research Questions

Christina River Basin CZO:What is the net carbon source or sink provided by the Christina River

Watershed?

My Research:

1.What is the composition and source of suspended material in White Clay

Creek?

2.Does eroded mineral material stabilize and transport organic carbon in the

fluvial network?

3.(How) does the fluvial transport of suspended material differ based on its

composition on seasonal and storm time scales?

(www.udel.edu/czo)


Research Questions

What is the composition and source of suspended material in White Clay Creek?


Approach

Sediment Fingerprinting – possible sources

Rill Erosion

Channel Banks(legacy sediments + buried

soil horizons, higher Fe)

Trail Crossing(animal evidence???)

Road Dust(high Zn)

Overland Flow(surface soil: high 7Be, C&N

reflect plant community)


Study Area

Bran

dyw

ine R.

Red

Clay C

k.

White Clay Ck.

Christina R.

White Clay Creek:

•Total area: 277 km2

•Wild and Scenic River for entire watershed

•Urban, agriculture, and forest land use

•Drinking water supply in areas of PA and DE

Christina River Basin:

•Total area: 1440 km2

•3 main tributaries – Brandywine River, Red

Clay Creek, White Clay Creek

•Urban, agriculture, and forest land use

•Sediment TMDL


ApproachSediment Fingerprinting1.Field collection of suspended materials, landscape materials, precipitation2.Analyze for several chemical signatures3.Use data in a statistical model to determine fraction of stream material from various sources

Particulate Analyses:•Fallout radionuclides (7Be, 137Cs, 210Pb) •C, N, stable isotopes•Mineral surface area•Grain size•Mineral content (elemental and composition)• Microbial community characterization (16S,

rRNA, PCR, ITS-DGGE, sequencing)•FTIR•Separate colloids quantification

Streamwater Chemistry:•TSS•DOC•Anions + Cations•Others?


Approach

Field Collection Precipitation for Radioisotopes

7Be7Be

7Be7Be

Radionuclide Fingerprints

•Precipitation delivered

•Strong particle surface affinity

•All radioactive, so primary method of ‘disappearance’ is decay.

•Plant interception not well known (recent source < 30%)

•Erosion tracers:

Beryllium-7 (54 days)

Lead-210 (22 years)

Cesium-137 (30 years)

Beryllium-10 (1.3 million years)


Approach

Field Collection of Precipitation

Open Precipitation Stemflow

Canopy Throughfall


Approach

Field Collection!

Challenge: collecting enough solid material for all analyses during baseflow and storms


ISCO automatic sampler for 1 L streamwater samples

Pressure transducer for water height

55 gallon barrel and cell-phone-triggered submersible pump for suspended sediment

Approach

Field Collection!

The “Dial-a-Pump”

55 gal.barrel

55 gal.barrel

float switchturns off pump

Cell phone

open sourceelectronics(Arduino)

submersible pump

12V marine battery


Approach

Field Collection!

The “Dial-a-Pump”Scaled Up: 3 barrels


ApproachSediment fingerprinting at nested sites in White Clay Creek

Field Collection – Locations

5th order – Newark DE

3rd order – Avondale PA

1st order – Avondale PA

• No significant difference in concentration per event with canopy when examining a year of data

Results - Rainfall

TreesLeaves

No TreesSummer

No TreesWinter

TreesNo Leaves

Results – Shallow Soil

• Similar 7Be (short lived!) profile in open and forested area• Longer-lived 137Cs shows mixture that occurs in ‘plow layer’• Signatures of these isotopes in the stream might help tell us about the depth from which

erosion and sediment delivery occur

Preliminary Results – Source /Suspended Variations


Preliminary ResultsSuspended Material – Storm Collections

Storm collections began 9/30/2010•1 large sediment sample per storm•Target peak •For example: 25 February 2011



Differences noted along storm hydrograph, beginning in April 2011



August 25 – September 12, 2011

Hurricane Irene

Tropical StormLee

66 metric tonssediment export

135 metric tonssediment export

54 metric tons In peak event

Preliminary Results – Radioisotope Fingerprinting

•7Be on stream sediment varies between seasons, with higher values in the spring and summer, and within single storms, with higher values generally earlier in a single event.

•One year of rainfall data does not show significant differences across seasons or in the presence or absence of a tree canopy.

•Does this mean the differences seen in stream material are from differences in erosion and delivery??????

soil A horizon,

river & coastal sediment

desert soil, B-C

horizon

deep ocean sediment

O hor

izon,

sedim

ent u

nder

anox

ic wat

er

leaf

litt

er,

alga

e

Mineral Surface Area (m2/g)0 20 40 60 80 100

Org

anic

car

bo

n (

%)

0

2

4

6

8

10

36

5249107

3301100

13973

26

<1

<1

<1

<1

2932

White Clay Creek POM with published sediment values

POM from White Clay Creek

Larger, temperate rivers (data from Keil et al. 1997, Mayer et al. 1994, Onstad et al. 2000)

Rivers draining deserts

Oxygen exposure times for marine sediments on the Washington shelf & slope and suboxic Mexican margin (data from Hartnett et al. 1998, Hedges et al. 1999, Keil et al. 2004)

<1

Preliminary Results

Preliminary Results - POM

•POM from White Clay Creek is relatively high in organic carbon content.• Organic carbon to surface area ratios closely resemble the surface soil

from the land cover types in the catchment – agriculture and forest.

•OC and mineral surface area change with season, but their ratio remains constant and characteristic of relatively ‘fresh’ material.

Jim PizzutoDel Levia

Adam PearsonElyse Williamson

Rolf AatloJulia Marquard

Anthony Aufdenkampe Steve Hicks

Dave MontgomeryStephanie Dix

Acknowledgements

CRB CZO work was funded by the National Science Foundation [NSF EAR 0724971]

SSH CZO work funded by an NSF EAR Postdoctoral Fellowship[NSF EAR 1144760]

Denis NewboldSara Geleskie

Fred ShawErika Vazquez

using chemistry to determine sediment source in white clay creek white clay wild and scenic...

Documents

suspended sediment slide

white clay creek urban

red clay creek

source of suspended

sediment source

storms photo

plant community slide

mineral material