Controls on the Emission and Composition of Dust Generated from Ash Meadows – Franklin Lake Playa, Mojave Desert,

Southwestern U.S.A.

Harland L. Goldstein1, George N. Breit1, James King2, James C. Yount1, Richard L. Reynolds1 and Marith C. Reheis1

1U.S. Geological SurveyDenver, Colorado, USA

2Desert Research InstituteLas Vegas, Nevada, USA

Ash Meadows – spring discharge areaFranklin Lake playa – wet playa

Wet playa

Dry playa

Mojave Desert

Franklin Lake playa(wet)

AmargosaRiver

Carson Slough

Ash Meadows

Setting

Sustained aridity suppresses dust emission

Wet episodes promote dust emission

Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul

Num

ber o

f day

s w

ithm

ultip

le d

ust e

mis

sion

s

0

2

4

6

8

10

Month and year

Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul

Prec

ipita

tion

mon

thly

tota

l (cm

)

0

2

4

6

8

Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul

Palm

er D

roug

ht S

ever

ity In

dex

-8

-6

-4

-2

0

2

4

6

8

10

Dust days

Precipitation

Drought index

Month and Year2004 2005 2006 2007 2008

no data

no data

>14400 images examined

Emission

Dus

t wt./

u*

0

10

20

30

40

50

60

November2007

April2008

February2009

Collect dust

Dust

Vacuum cleaner with cyclone impactor

Wind Tunnel Dust CollectionPI-SWERL I – November

2007 (Fall)

PI-SWERL II – April 2008 (Spring)

PI-SWERL III – February 2009 (Winter)

•Wind tunnel experiments conducted at 6 Sites

Meteorological Conditions, Surface Moisture and Dust

Moi

stur

e (w

t. %

)

1

2

3

4

5

6

November2007

April2008

June2008

October2008

Februrary2009

Dus

t wt./

u*

0

10

20

30

40

50

60

November2007

April2008

February2009

Tota

l Pre

cipi

tatio

n (c

m)

0

1

2

3

4

5

6

7

Mean Tem

perature (Celcius)

Relative H

umidity (Percent)

0

10

20

30

40

50

60

Total Precipitation (cm) Mean Air Temp (C) Mean Percent Humidity

PI-SWERLI

PI-SWERLII

PI-SWERLIII

Augu

stSe

ptem

ber

Octo

ber

Nove

mbe

rDe

cem

ber

2007

Janu

ary

Febr

uary

Mar

chAp

rilM

ay

Augu

stSe

ptem

ber

Octo

ber

Nove

mbe

rDe

cem

ber

June

July

Janu

ary

Febr

uary

2008 2009

Average Percent HumidityAverage Temperature (C)

Crust - Leach

% SO4

0 20 40 60 80 100

%C

l + %

CO

3

20

30

40

50

60

70

80

North Carson SloughDiscoveryCoppiceEast TransectClay DuneAsh Meadows

Sulfate DominatedChloride+Carbonate DominatedComposition

Dust-Crust Compositions(water soluble)

Chloride-Carbonate Sites

Soluble components:Crust 50 wt.%Dust 50 wt.%

Conductivity Alkalinity Chloride Sulfate Arsenic Uranium

S/cm mg/L mg/L mg/L g/L g/L

Conductivity Alkalinity Chloride Sulfate Arsenic Uranium

S/cm mg/L mg/L mg/L g/L g/L

Soluble components:Crust 13 wt.%Dust 50 wt.%

Dust-Crust Compositions (water soluble)

Sulfate Sites

Generally, when surface moisture declines so does the potential for dust generation

Dust generation is greatly reduced when excessive moisture is present

The proportion of soluble components in the dust varies depending on salt composition

Chloride-carbonate dominated crusts and resulting dusts are compositionally similar

Sulfate crusts generate dusts that are preferentially enriched in salts and soluble trace elements relative to the crusts.

Conclusions