Libya We can detect dust sources in several ways Wind models and back-trajectory analysis of air masses Where does dust come from ? Phoenix Jul 2011 Direct observation NW Africa Dust storm over Colorado & Kansas, April 8, 1999 Satellite images
April 2008 Wasatch Range Great Salt Lake Salt Lake City Dust Satellite images capture only the biggest dust storms in the West (and not at night or under cloud cover) MODIS, NASA DOS sites
Right side: Area treated with Plateau herbicide to kill exotic annual plants, then seeded with rangeland drill Left side: Untreated patch Lake Bonneville sediments Mark Miller Dust from Milford Flat – Site of the Largest Wildfire in Utah History Aridity (P/PET) (UNESCO classes) Arid Semiarid Subhumid Humid Size: >360,000 acres ~1,500 km 2 Mark Miller Milford Flat Fire Factors that promote dust emission from burn area Soils – Old lake sediments (silt and sand) Climate – arid and windy Landscape – high degree of wind exposure with wind corridors “Rehabilitation” ($25M) = Disturbance WIND
4 Mar 09, wind speed 13 m s -1 Dust sampler ~25 m away Horizontal dust flux at 1-m height, prior to peak of storm 234,200 g m -2 day -1 (~515 lbs) Very little dust from burned, untreated soil Massive dust emission from treated soil
Sevier Lake playa, UT Milford Flat, UT Old lake sediment + basalt, etc. Salt-mineral dust March 2009 Tom Painter, McKenzie Skiles, Annie Bryant April 30, 2009 Alta, Utah Dust layers DOS April 2008 Wasatch Range Dust ? ? Sources to Sink Can Dust-on-Snow (DOS) composition fingerprint dust sources ?
Dust particles that absorb solar radiation and greatly accelerate snow melt: Absorption of solar energy from Reflectance measures Fe oxide amount from magnetic measures Organic matter from organic C % Black carbon? correlation? Reflectance vs. organic matter Reflectance vs. Fe oxide amount Reflectance Fe oxide amount Reflectance C org (%) For each sample:
Reflectance Spectroscopy for determining radiative properties & Fe oxide minerals of dust samples Spectroscopy – study of objects based on the spectrum of color of light they emit or absorb Bi-directional method – fixed angles for incoming halogen light and for reflected light (fiber optic pick-up). Measurements converted to “absolute reflectance” by removing absorption of white reference
HIRM (Am 2 kg -1 ) Reflectance Visible avg. SOLA soil BSNE playa dust-on-snow Hematite + Goethite Fe oxides ~ 90 samples from Milford Flat 20%
Carbonaceous particles in Wasatch DOS Aggregate of carbon particles Carbon particle Cu + Zn 5 μm 2 μm SEM analysis by George Breit Carbonaceous matter influences reflectance Carbonaceous matter associated with METALS Organic carbon % Copper ppm Reflectance visible average Organic carbon %
What are the sources for these metals and carbon particles ? Bingham Canyon copper mine Salt Lake City Park City DOS sites
Milford Flat dust March 2009 Mark Miller, USGS Can we do anything to mitigate or minimize dust problems ? We need to know where it’s coming from, and why ? Can we do anything to mitigate or minimize dust problems ? We need to know where it’s coming from, and why ?
Dust-risk maps for land management Aeolian dunes over fine-grained lacustrine deposits Aeolian dunes over lacustrine gravel Fine-grained lacustrine deposits Aeolian dunes and fine-grained lacustrine deposits Area of fine-grained sediment-- Lake Bonneville extent ~ 16,000 yrs ago Wind Event: 17 Mar 2012, 1400 MDT 1.1-km resolution Map areas where soil & wind would combine to generate dust after surface disturbance Wind Field Milford Create GIS maps showing risks of disturbing & rehabilitating land NV UT ID
Dust from NE Arizona is deposited on Colorado mountain snow cover GOES MODIS image April 3, 2009 Northeastern Arizona Moderate Resolution Imaging Spectroradiometer Dust from the southern Colorado Plateau—the biggest dust sources today in the U.S.
Early Afternoon MODIS Image April 3, 2009 Northeastern Arizona Black Mesa Little Colorado R. Grand Canyon Moderate Resolution Imaging Spectroradiometer ChuskaMtns next slide
Tucker Flat, near Winslow, Arizona Little Colorado River dust corridor 4/27/2009 Jon Mason
Photo by Doug Barnum USGS Apr. 28, 2010 Dust from the southern Colorado Plateau to Colorado snow cover
Dust-on-Snow layers WY SASP San Juan Mts, Colorado Snow-layer studies by Chris Landry 2011 Year Events DOS events since
Why dust from southern Colorado Plateau? Physiographic setting (dry, windy) Tucker Flat 4/27/2009 Little Colorado River Many sources: many grazed, many not Collaboration with M. Redsteer Cholla power plant 18k acre feet yr -1 Is dust load increasing ? YES, but WHY ? Regional groundwater withdrawal ? Land-use practices (overgrazing) ? Regional aridity increasing? Drought -- ongoing Jon Mason
Why dust from Four Corners? Long history of wind erosion / dust emission Oct very old dunes modern dunes
Why dust from Four Corners? A major dust source – never grazed Toolani Lake 8/5/2012 Land-use practices (overgrazing) ? Many sources: many grazed, many not A major dust source – never grazed Tyende basin Oct. 2010
Dust is increasing across the West, apparently responding to increasing long-term aridity & current drought Canyonlands UT Mesa Verde CO Vernal UT Visibility below 3000 meters Janice Brahney, Univ. Colorado Dust on Snow events, SASP site Data from Chris Landry, CSAS Year Events DOS events since 2003 In the Jemez Mts (NM), was the driest 7-yr period during past 1200 yrs Touchan et al. 2011
Dust-on-snow N= Colorado New Mexico Utah Arizona nanohematite goethite Dominant iron oxide from Reflectance Spectroscopy Fe oxides are abundant in DOS. We can identify the dominant source region for a DOS layer based on dominant Fe oxide mineral
Two coal- fired power plants ~150 km Fly ash indicates inputs from combustion of coal Fly ash in dust-on-snow San Juan Mtns 15 m Fly ash “Black carbon” in San Juan Mtn Dust-on-Snow?
SASP WY 11 San Juan Mtns DOS collected by Chris Landry Coal particle in San Juan Mtn DOS open pit? feed coal? natural dust source? But from what source: SEM analysis by George Breit
Photo by Doug Barnum USGS Apr. 28, 2010 Dust from the southern Colorado Plateau Can we do anything to mitigate or minimize dust problems ?
Photo by Doug Barnum USGS Apr. 28, 2010 Dust from the southern Colorado Plateau Stable soil surfaces (perennial vegetation and biologic soil crust) Stable sand dunes (veg cover) Invasive plants (temporary; not during droughts) High soil moisture High groundwater levels to Colorado snow cover Factors that suppress dust emission
Photo by Doug Barnum USGS Apr. 28, 2010 Dust from the southern Colorado Plateau Can we do anything to mitigate or minimize dust problems ? Will, Knowledge, Resources, Collaboration