Upcoming Meetings

All are welcome – no admission charge
Social Hour starts at 6:30, meeting at 7:00

Wednesday, December 13, 2017

DUST! Why Should You Care? (the answer is blowing in the wind)

Marith Reheis, Emeritus USGS

Eastern Colorado, June 2008, The Denver Post

All are welcome; no admission charge.

Note: This meeting is on a Wednesday, not on Thursday.
We will have a potluck dinner before the address.
6:00-7:00 PM, Social time with light refreshments
7:00-9:00 PM, Program

At The Arbor House, Maple Grove Park (Applewood area)
14600 W 32nd Ave., Golden CO 80401

Arbor House on map

Abstract: Windblown dust is carried all over the world, whether visible or not. Earth-derived dust today is most abundant in arid and semi-arid regions, and in the glacial past in glacio-fluvial areas. So why is dust important? Let me count some of the ways: (1) agriculture, (2) ecosystems, (3) dust storms, (4) water supply, (5) human (and animal) health. Dust is the great equalizer of the Earth’s surface, because it is the only component (along with other wind-borne materials like volcanic ash and anthropogenic pollutants) that circles the planet.
Dust can be rich in mineral nutrients such as potassium, phosphorus, magnesium, manganese, copper, zinc, boron, and molybdenum. Transported dust is either deposited as a blanket (loess) or added to soils. Loess forms the substrate for the richest crop-growing areas on the planet; dust added to soils contributes critical plant nutrients that may not be available in the parent material. For instance, we now know that dust from Africa provides most of the mineral nutrients external to that held in the biomass to the Amazon rain forest. Dust forms the vast majority of silt and clay-sized particles present in desert soils and dust from distant sources is present in nearly every soil on the planet. Dust is trapped and retained by the biological crust that binds surface sediment in drylands, and thus plays an important role in dryland ecosystems.
What dust brings, it can take away in the form of blinding dust storms with consequences for agriculture, human health, and water supply. The effects of the terrible dust storms of the Dust Bowl days on soil erosion and people are well known. Exposure to excessive amounts of dust can cause asthma and silicosis and can trigger heart attacks and strokes. Dust from some soil surfaces can carry the anthrax bacterium or fungal spores that cause valley fever (coccidiomycosis). And dust from some natural sources, such as desert playas and lakes dried up due to over-use of water, can contain high concentrations of toxic elements such as arsenic, antimony, tungsten, chromium, and lithium. Ongoing studies are showing that dust, when deposited on spring snowpack, decreases reflectivity. This causes snow to melt earlier and faster, and can sharply reduce water supply in late summer and fall.

Marith Reheis

Short Biography of Marith Reheis: I graduated with a B.S. in Geology from the University of Georgia in 1972. Desperate to escape from humidity and saprolite, I earned an M.S. from the University of Colorado studying the transport of debris by Arapaho Glacier. After a few years mapping coal in the Conservation Division of USGS, I returned to CU Boulder to study soil genesis under Pete Birkeland. From 1984 to retirement in 2013, I’ve resided in the evolving branches of Regional Geology — Environmental Geology — Climate — Earth Surface Processes – Geosciences and Environmental Change Science Center. Field areas included northwest Colorado, the Bighorn Basin, Great Basin and Mojave Deserts, and the eastern Colorado Plateau. In parallel, my career has evolved through bedrock and surficial mapping, soil studies, neotectonics, desert dust sampling and analysis, and paleoclimate research, to a state of mixing them all together.

General Information about Meetings

All are welcome – no admission charge
Social Hour starts at 6:30, meeting at 7:00

Meetings are normally at (but not this September or December):
Shepherd of the Hills Presbyterian Church
11500 W. 20th Ave., Lakewood CO

See Abstracts (under Events) for previous Colorado Scientific Society Talks