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ground-level wind speed at the 2-m height of the dust trap and
permit comparison of the amount of dust caught by an unshielded
trap with the amount that should be caught at ground level where
vegetation breaks the wind.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Trap locations were ascertained by plotting their
positions on USGS topographic maps at 1:24000 scale.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: National Climatic Data Center
Publication_Date: 1961-1990
Title: California: Climatological Data Annual Summary
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1992
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: NCDC 61-90 A CA
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Source_Information:
Source_Citation:
Citation_Information:
Originator: National Climatic Data Center
Publication_Date: 1961-1990
Title: Nevada: Climatological Data Annual Summary
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1992
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: NCDC 61-90 A NV
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Source_Information:
Source_Citation:
Citation_Information:
Originator: National Climatic Data Center
Publication_Date: 1992
Title:
California: Monthly station normals of
temperature, precipitation, and heating and
cooling degree days 1961-1990
Series_Information:
Series_Name: Climatography of the United States
Issue_Identification: 81
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1992
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: NCDC 61-90 M CA
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Source_Information:
Source_Citation:
Citation_Information:
Originator: National Climatic Data Center
Publication_Date: 1992
Title:
Nevada: Monthly station normals of temperature,
precipitation, and heating and cooling degree days
1961-1990
Series_Information:
Series_Name: Climatography of the United States
Issue_Identification: 81
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1992
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: NCDC 61-90 M NV
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Department of Commerce (Weather Bureau)
Publication_Date: 1964
Title:
California: Climatic summary of the United States--
Supplement for 1951 through 1960
Series_Information:
Series_Name: Climatography of the United States
Issue_Identification: 86-4
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1964
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: DOC 51-60 CA
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Source_Information:
Source_Citation:
Citation_Information:
Originator: U.S. Department of Commerce (Weather Bureau)
Publication_Date: 1964
Title:
Nevada: Climatic summary of the United States--
Supplement for 1951 through 1960
Series_Information:
Series_Name: Climatography of the United States
Issue_Identification: 86-4
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1964
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: DOC 51-60 NV
Source_Contribution:
Data used to calculate mean annual temperature (MAT) and
mean annual precipitation (MAP) at dust trap sites
Process_Step:
Process_Description:
The most important factors that influenced dust-trap
design in this study were: (1) measuring the amount of
dust added to soils; (2) sampling on an annual basis; (3)
no protection other than being hard to find; and (4) the
cost and ready availability of components that might have
to be replaced from sources in small towns. The original
design consists of a single-piece Teflon-coated angel-food
cake pan (see note 1) painted flat black on the outside to
maximize water evaporation and mounted on a steel fence
post about 2 m above the ground. A circular piece of 1/4-
inch-mesh galvanized hardware cloth is fitted into the pan
so that it rests 3-4 cm below the rim, and glass marbles
fill the upper part of the pan above the hardware cloth.
The Teflon coating is non-reactive and adds no mineral
contamination to the dust sample should it flake. The
hardware cloth resists weathering under normal
conditions. The 2-m height eliminates most sand-sized
particles that travel by saltation rather than by
suspension in air; sand grains are not generally pertinent
to soil genesis because they are too large to be
translocated downward into soil profiles. The marbles
imitate the effect of a gravelly fan surface and prevent
dust that has filtered or washed into the bottom of the
pan from being blown away. The empty space below the
hardware cloth provides a reservoir that prevents water
from overflowing the pan during large storms. This basic
design was modified in 1986 in two ways. In many areas,
the traps became favored perching sites for a wide variety
of birds. As a result, significant amounts of non-eolian
sediment were locally added to the samples (as much as
five times the normal amount of dust at some sites). All
dust traps were fitted with two metal straps looped in an
inverted basket shape over the top and the top surfaces of
the straps were coated with Tanglefoot. [Use of trade
names by the U.S. Geological Survey does not constitute an
endorsement of the product.] This sticky material never
dries (although it eventually becomes saturated with dust
and must be reapplied) and effectively discourages birds
from roosting. In addition, extra dust traps surrounded
by alter-type wind baffles were constructed at four sites
characterized by different plant communities. These
communities and sites are: blackbrush (Coleogyne
ramosissima), creosote bush (Larrea divaricata), and other
low brushy plants at sites 1-5 on Fortymile Wash; Joshua
tree (Yucca brevifolia), other tall yucca species, and
blackbrush at site 18 on the Kyle Canyon fan; pinyon-
juniper (Pinus monophylla-Juniperus sp) at site 7 on
Pahute Mesa; and acacia (acacia sp), creosote bush, and
blackbrush at site 26 near the McCoy Mountains. The wind
baffles imitate the effect of ground-level wind speed at
the 2-m height of the dust trap and permit comparison of
the amount of dust caught by an unshielded trap with the
amount that should be caught at ground level where
vegetation breaks the wind.
Process_Date: 1984
Process_Step:
Process_Description:
Samples were obtained from the dust traps by carefully
washing the marbles, screen, and pan with distilled water
into plastic liter bottles. In the laboratory, the sample
was gradually dried at about 35癈 in large evaporating
dishes; coarse organic material is removed during this
process. Subsequent analyses on dust samples included, in
the order they were performed: (1) moisture, (2) organic
matter, (3) soluble salts and gypsum, (4) total carbonate
(calcite plus dolomite), (5) grain size, (6) major-oxide
chemistry, and (7) mineralogy (sand, silt, and clay
fractions). The database for any given site commonly
contains gaps depending on how far the sample for a
particular year could be stretched through the analytical
cascade. In some cases, samples from different years at
the same site or adjacent sites were combined to obtain
enough material for measuring grain size.
A sample was commonly retrieved and used in more than one
analysis if the first analytical procedure used was non-
destructive. These sequential analytical techniques
included: (1) Moisture and organic-matter content (Walkley-
Black procedure in Black, 1965) were measured on the same
split using 0.05 g. (2) The entire sample was used to
extract the solution to measure soluble salts (Jackson,
1958) and was then dried and recovered; thus, subsequent
analyses were performed on samples without soluble
salts. (3) A 0.25-g split was used to analyze total
carbonate (Chittick procedure in Singer and Janitzky,
1986). This split, free of carbonate after the analysis,
was recovered and used to analyze for major oxides and
zirconium. (4) When sufficient sample (0.4 g) existed to
obtain grain size using the Sedigraph rather than by
pipette analysis, the clay and silt fractions were saved
and used to analyze mineralogy by X-ray diffraction.
Most of the laboratory analyses were performed in the
Sedimentation Laboratory of the Institute of Arctic and
Alpine Research in Boulder, Colorado, using standard
laboratory techniques for soil samples (see Black, 1965,
and Singer and Janitzky, 1986) that we adapted for use on
very small samples (the non-organic content of a dust
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