Reheis, M.C., and Kihl, R., 1995, Dust Deposition in Southern Nevada and California, 1984-1989: Relations to Climate, Source Area, and Lithology, Journal of Geophysical Research, v. 100D5, p. 8893-8918.
The average silt-plus-clay flux in southern Nevada and southeastern California ranges from 4.3 to 15.7 g/m2/yr, but in southwestern California the average flux is as high is 30 g/m2/yr. These rates are generally less than those of previous studies in the arid southwestern United States, probably due to differences in measurement techniques (other studies mostly used traps at lower heights and did not exclude bird- derived sediment).
The climatic factors that affect dust flux interact with each other and with the factors of source type, source lithology, geographic area, and human disturbance. For example, average dust flux increases with mean annual temperature but is only weakly related to decreases in mean annual precipitation, because the prevailing winds bring dust to relatively wet areas. In contrast, annual dust flux mostly reflects changes in annual precipitation rather than temperature. Although playa and alluvial sources emit about the same amount of dust per unit area, the volume of dust from the more extensive alluvial sources is much larger. In addition, playa and alluvial sources respond differently to annual changes in precipitation. Most playas emit dust that is richer in soluble salts and carbonate than that from alluvial sources (except carbonate-rich alluvial fans), but the dust-deposition rates do not reflect this trend: salt flux tends to be larger in mountain ranges, and gypsum flux parallels carbonate flux. Gypsum dust may be produced by the interaction of carbonate dust and anthropogenic sulfates. Cultivated areas generally yield about 20 percent more dust than uncultivated areas. The dust flux in an arid urbanizing area may be as much as twice that before disturbance, but decreases when construction stops.
The mineralogic and major-oxide composition of the dust samples indicate that sand and some silt is locally derived and deposited, whereas clay and some silt from different sources can be far-travelled. Dust deposited in the Transverse Ranges of California by the Santa Ana winds appears to be mainly derived from sources to the north and east.
Introduction
The source, entrainment, transportation, and deposition of eolian dust are
topics of increasing interest in the scientific community and increasing
importance to the global community. Topics that are addressed in this
study include: (1) Dust generation is a direct result of aridification
and thus it mirrors the effects of climatic change and of human impact on
dust-prone areas. An increased frequency and magnitude of dust storms
will have a strong negative impact on human infrastructure. (2) Dust has
been shown to be a major component of soils in both arid and humid areas.
Dust is important to soil fertility and can control the chemistry of
precipitation. In arid and semiarid areas, eolian dust plays a
significant role in soil formation and geomorphic process (e.g., formation
of desert pavements). (4) Detailed studies of dust influx can permit
better estimations of paleoclimate from soil properties such as the amount
and depth of pedogenic carbonate.
Although there have been many studies of airborne dust in the southwestern United States, most have focused on the components that represent anthropogenic pollution. Moreover, few sites outside densely populated regions such as Las Vegas and the Los Angeles-San Diego area are monitored regularly by such networks as the National Atmospheric Deposition Program.
A project to study modern dust deposition relative to soils in southern Nevada and California was initiated in 1984 under the auspices of the Yucca Mountain Site Characterization Project (Interagency Agreement DE-AI08-78ET44802). The primary purpose of the dust-deposition project was to provide data on modern dust composition and influx rates to a computer model relating soil carbonate to paleoclimate. A secondary purpose was to provide data on dust influx rates at specific sites in the southern Great Basin and Mojave Desert where soil chronosequences were studied in support of tectonic and stratigraphic investigations for the Yucca Mountain Project. The initial 46 sampling sites, including one site with five traps, were established in 1984 and were supplemented by nine more sites in 1985 to provide dust data to soil studies by other investigators along the Elsinore Fault and in the Transverse Ranges of southern California.
Previous studies of dust deposition in relation to soils have generally been restricted to a small area (such as the Channel Islands, Calif.) or region (such as the Edwards Plateau, Texas) and collected samples only for one year. Exceptions include a regional, two-year study on the Great Plains, a local, ten-year study in the Las Cruces area, New Mexico, and a three-year study on Crete. To our knowledge, our dust-deposition project is the first such project to be both regional in extent and long-term.
The purpose of this research is to obtain data on the composition and deposition rate of eolian dust in southern Nevada and California from 1984 to 1989, and to relate these properties to controlling variables such as climate, lithology of local dust source, and type of source. Further work will relate modern dust to soil properties and compare modern rates of dust influx with long-term rates estimated from soils at selected sites.
Sampling, laboratory procedures, and mathematical equations
[Editor's note: This section is divided into subsections, each pertaining
to a file or group of files that can be found in other directories of this
data set. Each subsection is preceded by a list of the relevant files,
including both the portable versions, which are found in subdirectories of
Core/, and the DOS versions supplied by the author, which are found in
Derived/dos.]
Files Core/meta/trapsite.txt
Derived/dos/data/dustloc.xls
The sampling design for this study was not statistically based; rather,
sites were chosen to provide data on dust influx at soil-study sites and
to answer specific questions about the relations of dust to local source
lithology and type, distance from source, and climate. Some sites were
chosen for their proximity to potential dust sources of different
lithologic composition (for example, playas versus granitic, calcic, or
mafic alluvial fans). Other sites were placed along transects crossing
topographic barriers downwind from a dust source. These transects
include sites east of Tonopah (43-46) crossing the rhyolitic Kawich Range,
sites downwind of northern (40, 35, 36) and central Death Valley (38, 39,
11-14) crossing the mixed-lithology Grapevine and Funeral Mountains,
respectively, and sites downwind of Desert Dry Lake crossing the
calcareous Sheep Range (47-50) north of Las Vegas. In addition, some
sites were chosen for their proximity to weather stations.Specific locations for dust traps were chosen on the basis of the above criteria plus accessibility, absence of dirt roads or other artificially disturbed areas upwind, and inconspicuousness. The last factor is important because the sites are not protected or monitored; hence, most sites are at least 0.5 mile from a road or trail. Despite these precautions, dust traps are sometimes tampered with, often violently. This is a particular problem in areas close to population centers, and most of these sites (52-55 near Los Angeles and 17-19 and 22 near Las Vegas) have been abandoned. A few other sites, mostly those that appeared to be greatly influenced by nearby farming (20, 21, and 41), were eliminated in 1989. Dust traps were also generally placed in flat, relatively open areas to mitigate wind-eddy effects created by tall vegetation or topographic irregularities.
The 55 sites established in 1984 and 1985 were sampled annually through 1989 in order to establish an adequate statistical basis to calculate annual dust flux. Sampling continues at 37 of these sites (many sites now have two or more dust traps) every two or three years as opportunity and funding permit.
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.
Files Core/raw/labdust.txt
Derived/dos/labdust.xls
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°C 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 sample collected from one trap typically weighs less than 1 g/yr). These adaptations generally result in larger standard errors than normal for the results of different techniques because the amount of sample used is smaller than the recommended amount.
Files Core/raw/flux.txt
Core/raw/flux_avg.txt
Derived/dos/fluxmod.xls
Total dust flux is calculated by multiplying the mineral weight times the
fraction less than 2 mm times the pan area times the fraction of year
during which the sample accumulated (in file labdust.xls, number of days
divided by 365). Other dust-flux values for various components (i.e. silt
flux) are calculated by multiplying the total dust flux by the percentage
of the component.Preliminary examination of the flux data indicated that samples from some sites collected in 1985 and 1986, before the trap design was modified to discourage birds from roosting, were anomalously large (50-500% greater) compared to those collected in later years. All of the anomalous samples had been recorded as having significant amounts of bird feces at the time of collection. Consultations with bird biologists confirmed that bird droppings can contain significant amounts of mineral matter, mostly derived from cropstones; the amount varies with the species and with the diet of local populations of individual species. Moreover, perching birds can contaminate the sample with material from their feet. In some cases, we have evidence of near-deliberate contamination in the form of one or two pebble-sized clasts of local rocks that were found in samples, possibly dropped (or swapped for marbles) by large birds such as ravens. Data from samples with large amounts of bird droppings were discarded from further analysis and were excluded from the computations of "selected average" flux values.
Files Core/raw/chemistry/data/dusticp.txt
Derived/dos/data/dusticp.xls
Major elements were measured in U.S. Geological Survey laboratories on a
split of the less-than-2mm fraction remaining after analysis and removal
of carbonate by the Chittick method. Major elements and zirconium were
analyzed by induction-coupled plasma spectroscopy (Lichte and others,
1987). In some cases, samples from different years at the same site or
adjacent sites were combined to obtain enough material for measuring major-
oxide composition.
Files Core/raw/chemistry/data/dustox.txt
Derived/dos/data/dustox.xls
Major oxides are calculated from elemental compositions (file dusticp.xls)
using the following equations based on atomic weights:
SiO2 = Si/0.467
Al2O3 = Al/0.529
Fe2O3 = Fe/0.699
MgO = Mg/0.603
CaO = Ca/0.715
Na2O = Na/0.742
K2O = K /0.830
TiO2 = Ti/0.599
MnO = Mn/0.774
ZrO2 = Zr/0.740
The percentages of major oxides and zirconium were then recalculated to
100%, excluding water, volatiles, and minor elements, and the ratios of
major oxides to ZrO2 are based on the recalculated values.
Files Core/raw/minerals/sandmin.txt
Core/raw/minerals/siltmin.txt
Core/raw/minerals/claymin.txt
Core/raw/minerals/combine.txt
Derived/dos/data/dustmin.xls
Mineralogy was measured in U.S. Geological Survey laboratories on splits
of samples that had been previously analyzed for grain size. Samples of
sand, silt, and clay were slurried in water (sand samples were ground to a
fine powder) and mounted dropwise on glass slides. Minerals in the sand
and silt fractions were identified by characteristic peaks on X-ray
diffractograms and their relative amounts were estimated by measuring peak
heights. Minerals in the clay samples were identified by characteristic
peaks obtained after the following treatments: air-dried, glycolated, and
heated to 300°C and 550°C. The relative abundances of
clay minerals were estimated by measuring the following peak heights (in
degrees 2 theta) and adjusted for intensity variations between runs using
the peak height of quartz at 26.65 2 theta: chlorite, 6.3 on the 550°C
trace; kaolinite, 12.6 on the glycolated trace minus the amount
of chlorite; mica, 8.8 on the glycolated trace; smectite, 5.2 on the
glycolated trace; mixed-layer mica-smectite, 8.85 on the 550° trace
minus the amounts of mica and smectite.
Files Core/raw/climate/aveclim.txt
Core/raw/climate/history/
Derived/dos/aveclim.xls
The National Climatic Data Center no longer publishes mean climatic data
for the entire length of record at weather stations. To obtain mean
annual temperature (MAT) and precipitation (MAP) for the weather stations
nearest the dust traps, averages had to be computed from climatic
summaries of the United States (U.S. Department of Commerce, 1952, 1965),
from station normals for 1961-1990 (National Climatic Data Center, 1992),
and from various climatological data annual summaries. Comparisons could
then be made of the long-term averages with those for the five years of
dust collection (file climate.xls).
Files Core/raw/climate/climreg.txt
Derived/dos/climreg.xls
The dust-trap sites are at different elevations from the nearest weather
stations. To estimate mean annual temperature (MAT) and precipitation
(MAP) at the sampling sites, annual climate data for the entire period of
record was obtained for every weather station in the region, including
some that are no longer maintained but excluding those in coastal
California. The data in this file was combined from the data in file
aveclim.xls, which included the weather stations nearest the traps, and
from climatic data for other stations. For many stations with relatively
complete records, this involved computation of the averages of MAT and
MAP (columns under "MAT calculations" and "MAP calculations") compiled
from records prior to 1961, the last year in which averages for the entire
length of record were published by the U.S. Department of Commerce (1965),
and from station normals for 1961-1990 (National Climatic Data Center,
1992). Normals and averages are not published for stations with missing
data or those which were moved at some time; for these stations, the
computation required hand-entering data for each year of record from the
climatological data annual summaries (columns under "MAT records" and "MAP
records").Linear regression (bottom left of file) was used to obtain equations that relate temperature and precipitation to elevation for these weather stations (columns "Elevation", "MAT", and "MAP") and to estimate these parameters at sampling sites with different elevations. For temperature, only one equation was required; it provides estimates with a standard error (s.e.) of only 1.3°C. For precipitation, equations were most useful when the stations were divided into three geographic regions, including the area of the Mexican border and the Colorado River-southeast Nevada corridor (s.e.=2.6 cm), southwestern California east of the Transverse Ranges (s.e.=8.6 cm), and the interior deserts (s.e.=2.0 cm).
Files Core/raw/climate/trapclim.txt
Derived/dos/trapclim.xls
Estimates of MAP and MAT listed under "this study" were obtained using the
linear regression equations calculated from data in file regclim.xls.
These equations are:
MAT = -0.0072E+23.4 MAP (interior deserts) = 0.00555E+7.075 MAP (Colorado River-Salton Sea) = 0.01013+7.468 MAP (SW California) = 0.05E+5.002where E is elevation in meters. For comparison, MAP is also calculated using other published equations. For stations on the Nevada Test Site (T-1 through T-9) I used the equation of Quiring (1983), in which y = MAP in inches and x = elevation in thousands of feet:
y = 1.36x - 0.51For stations in southern Nevada, including the Nevada Test Site, I used the equations of French (1983), in which y = MAP in inches and x = elevation in feet. French (1983) divided southern Nevada roughly into thirds based on the paths of moisture-carrying air masses from the west and south; the eastern third has the most rainfall, the western third has the least, and the central third is intermediate:
Eastern: log y = 0.0000933x + 0.486 Central: log y = 0.0000786x + 0.446 Western: log y = 0.0000365x + 0.505MAP at the closest weather station to the dust-trap site is also given. Estimates of MAP for sites near Los Angeles, including T-51 through T-54, using the equations from this study gave unrealistically low values (see file trapclim.xls) because this area is under a coastal rather than an interior climate. Thus, in the papers written using these data, MAP for these sites is assumed to be about the same as that at the nearest weather station.
Files Core/raw/climate/climate.txt
Core/raw/climate/last6yrs/
Derived/dos/climate.xls
Mean monthly precipitation and temperature from 1984 to 1989 were acquired
from the National Climatic Data Center (1984-1989) for weather stations in
southern Nevada and California that were closest to dust-trap sites and
entered into a spreadsheet in order to calculate mean annual values for
climatic variables and compare them to long-term means (calculated in file
aveclim.xls). Seasonal precipitation (May-October and November-April) was
calculated from monthly values.
Files Core/raw/climate/climpet.txt
Derived/dos/climpet.xls
Secondary climatic variables were calculated from the data in file climate.
xls. These secondary variables include monthly and annual potential
evapotranspiration (PET) and the leaching index (LI) of Arkley (1963).
The leaching index is a measure of available moisture obtained by
subtracting monthly evapotranspiration from monthly precipitation. PET
was calculated for all stations with both temperature and precipitation
data using the method of Thornthwaite (1948), and for stations with mean
minimum and maximum temperatures using the method of Papadakis (1965).
The leaching index is calculated for both methods of PET. Pan evaporation
measurements are also given where available (National Climatic Data Center
and Farnsworth and others, 1982) for comparison.PET is more readily calculated by the Thornthwaite method than by the Papadakis method, because the latter requires mean minimum and maximum temperatures that are commonly not recorded at some weather stations. However, according to Taylor (1986), the Thornthwaite method applied to climatic data for arid regions yields PET values that are much too low (as much as 150% compared to evaporation-pan data for the growing season). The Papadakis method provides estimates of PET that are closest to pan data in arid climates. Many thanks to Emily Taylor (U.S. Geological Survey) for guiding me through the complex calculations of PET and providing me with the appropriate references.
Marith C. Reheis
Box 25046, MS 913
Denver Federal Center
Denver, CO 80225
Tel: (303) 236-1270
FAX: (303) 236-0214
Where analyses were made based on samples of mixed years and more than one trap site, I have supplied an additional table called "combine.txt" indicating which samples were combined (using the same notation).
I have altered the data files in Core/ to adhere to this convention in the hope that the resulting files will be more easily imported into data base management systems.
The files *.txt were exported from a spreadsheet program, and any cell values that contained a comma were enclosed in quotation marks. This feature will ease the import of these files into other spreadsheet programs, but may hinder their use with DBMS. ]
----------------------------------------------------------------------
Files Core/meta/samples.txt
Derived/dos/trap.xls
Variable names from Core/meta/samples.txt:
Trap sample id
Lab No. (GRL-)
Days out
Problem?
1985-6 changes:
Traps 1-3, 18, and 18A fitted with bird defenses on 1/6/86, and remainder
fitted at collection time. Placed wind baffle around T-3 on 1/5/86;
erected wind-baffle trap 18A on 1/6/86. Wind-baffle traps T-7A and T-26A
erected October 1986.
1986-7 changes:
Added top screens to traps 22,42,43,44,46,54 to prevent marble loss.
1987-8 changes:
Added top screens to traps 24,35,37 to prevent marble loss.
1988-9 changes:
See modification column. "Doubled" indicates additional trap erected;
"dismantled" indicates site abandoned.
Key to problems column:
*** Piles of bird shit
** Lots of bird shit
* Some bird shit
! Trap leaked water (cause in parentheses if known)
O ORVs probably operating upwind or nearby; possibly extra dust present
@ Marbles knocked out by quadrupeds; post bent from scratching, etc.
# Human problem: marble theft, bullet holes etc.
----------------------------------------------------------------------
Files Core/meta/trapsite.txt
Derived/dos/data/dustloc.xls
Variable names from Core/meta/trapsite.txt:
trap
latitude
longitude
elevation (m)
geographic area
transect (km)*
primary source source**
primary source lithology***
secondary source source**
secondary source lithology**
* Distance in km downwind from a dust source; only given for sites
located on transects.
** Primary source is the closest or most dominant dust source to the
trap; secondary source is the next closest or dominant source. Same
applies to lithology. Source key: 1, alluvium; 2, playa; 3, dunes;
4, bedrock
*** Lithology key:
1 granitic
2 rhyolitic
3 basaltic
4 metamorphic
5 limestone (may include quartzite; also used for playa and lacustrine deposits)
6 mixed
----------------------------------------------------------------------
Files Core/raw/labdust.txt
Derived/dos/labdust.xls
Variable names from Core/raw/labdust.txt:
Trap sample id
Lab# (GRL-)
Days out
Organic carbon %
Organic matter %
%CaCO3 (total)
%CaCO3 (OM-free)
%salts (total)
%salts (OM-free)
%gypsum (total)
%gypsum (OM-free)
Mineral wt (g)**
% <2mm
sand % of <2mm fraction
silt % of <2mm fraction
clay % of <2mm fraction
textural class
-- Not measured
Notes:
Traps 3 and 18A fitted with wind baffles on 1/6/86; new traps 7A and 26A
erected and fitted with baffles on collection day.
Quote marks in the percent sand, silt, and clay columns indicate
percentages are the same as the sample values directly above because the
samples were combined for grain-size analysis. Quote marks followed by a
GRL- lab number indicate sample was combined with another not directly
above.
Textural class based on soil texture triangle using percent sand, silt,
and clay. Numbers in texture column indicate year of sample from the same
site combined with that of the current year for grain-size analysis.
C = clay
CL = clay loam
Si = silt
SiC = silty clay
SiL = silt loam
SiCL = silty clay loam
L = loam
S = sand
SL = sandy loam
SCL = sandy clay loam
* In texture column, indicates particle size of silt and clay fractions
analyzed by Sedigraph; no symbol, analysis by pipette.
** Mineral weight excludes organics, oven-dry basis
----------------------------------------------------------------------
Files Core/raw/flux.txt
Core/raw/flux_avg.txt
Core/raw/flux/CO3.txt
Core/raw/flux/salt.txt
Core/raw/flux/gypsum.txt
Core/raw/flux/min_wgt.txt
Core/raw/flux/CO3_flux.txt
Core/raw/flux/saltflux.txt
Core/raw/flux/gypsflux.txt
Core/raw/flux/data/dustflux.txt
Core/raw/flux/sandflux.txt
Core/raw/flux/siltflux.txt
Core/raw/flux/clayflux.txt
Derived/dos/fluxmod.xls
Variable names from Core/raw/flux.txt:
Trap
CO3
salt
gypsum
min_wgt_Q
min_wgt
dustflux_Q
dustflux
CO3_flux_Q
CO3_flux
saltflux_Q
saltflux
gypsflux_Q
gypsflux
sandflux_Q
sandflux
siltflux_Q
siltflux
clayflux_Q
clayflux
Variable names from Core/raw/flux_avg.txt:
Trap
CO3_avg
salt_avg
gypsum_avg
min_wgt_avg
min_wgt_sel_avg
dustflux_avg
dustflux_sel_avg
CO3_flux_avg
CO3_flux_sel_avg
saltflux_avg
saltflux_sel_avg
gypsflux_avg
gypsflux_sel_avg
sandflux_avg
sandflux_sel_avg
siltflux_avg
siltflux_sel_avg
clayflux_avg
clayflux_sel_avg
Variable names from Core/raw/flux/*.txt:
Trap
Q85 data quality notation (min_wgt and ????flux files only)
1985 measured value
Q86
1986
Q87
1987
Q88
1988
Q89
1989
average
Selected average
Pan catchment area: 431.03 cm2 (from D. L. Weide, 11/18/85)
Notations in mineral-weight and flux columns:
x Value thought to be much too large due to the volume of bird
droppings, etc.
P Value possibly too large due to factors specified in file trap.xls
(ORV traffic, gravel pit operation, etc.)
N Value possibly too small due to factors specified in file trap.xls
(leaking pan, marbles knocked out by grazing animals, etc.)
Average columns include all data.
Selected-average columns exclude data preceded by x (bird-contaminated
samples).
[Editor's note: The data quality notations were separated from their
accompanying measurements using the program
Core/meta/fix_columns.c
The files flux.txt and flux_avg.txt were derived from
fluxmod.xls using the procedure described in Core/meta/reform.]
----------------------------------------------------------------------
Files Core/raw/minerals/sandmin.txt
Core/raw/minerals/siltmin.txt
Core/raw/minerals/claymin.txt
Core/raw/minerals/combine.txt
Derived/dos/data/dustmin.xls
Variable names from Core/raw/minerals/claymin.txt:
Sample no.
Chlorite
Kaolinite
Mica
Smectite
Mixed-layer
Quartz
Other
Variable names from Core/raw/minerals/sandmin.txt:
Sample no.
Quartz
Anorthoclase
High-temp sanidine
High-temp albite
Anorthite
Orthoclase
Microcline
Low-temp albite
Muscovite + biotite
Pyroxene
Hornblende*
Dolomite
Calcite
Other
Variable names from Core/raw/minerals/siltmin.txt:
Sample no.
Quartz
Anorthoclase
High-temp sanidine
High-temp albite
Anorthite
Orthoclase
Microcline
Low-temp albite
Muscovite + biotite
Chlorite
Apatite
Pyroxene
Hornblende*
Dolomite
Other
Variable names from Core/raw/minerals/combine.txt:
combined sample id
component sample 1
component sample 2
component sample 3
component sample 4
component sample 5
component sample 6
Sample number shows sample combinations. For example, T-3,4,5-87 means
that samples from traps 3, 4, and 5 taken in 1987 were combined for
analysis; T-38-87,88,89 means that samples from trap 38 taken in 1987,
1988, and 1989 were combined for analysis.
* Hornblende chiefly consists of actinolite and tremolite.
-- Not present
N.D. Not determined
tr Trace amount
Numerical values obtained by measuring peak heights; see above for methods.
----------------------------------------------------------------------
Files Core/raw/chemistry/data/dusticp.txt
Core/raw/chemistry/combine.txt
Derived/dos/data/dusticp.xls
Variable names from Core/raw/chemistry/data/dusticp.txt:
Traps
Si
Al
Fe
Mg
Ca
Na
K
Ti
Mn
Zr
More than one number indicates samples from the listed traps were combined
for analysis. Numbers in parentheses indicate samples from different
years were combined for analysis. Water and volatiles not reported.
* Analyses for 1984-85 were performed on samples containing carbonate;
analyses for all subsequent years were performed on samples without
carbonate (on the fraction remaining after Chittick analysis). Si
content was not measured on 1984-85 samples.
X No data
----------------------------------------------------------------------
Files Core/raw/chemistry/data/dustox.txt
Core/raw/chemistry/combine.txt
Derived/dos/data/dustox.xls
Variable names from Core/raw/chemistry/data/dustox.txt:
Traps
raw SiO2 major oxides
raw Al2O3
raw Fe2O3
raw MgO
raw CaO
raw Na2O
raw K2O
raw TiO2
raw MnO
raw ZrO2
norm SiO2 recalculated to 100% (no water or volatiles)
norm Al2O3
norm Fe2O3
norm MgO
norm CaO
norm Na2O
norm K2O
norm TiO2
norm MnO
norm ZrO2
Si/Zr02 ratios of major oxides to Zr02
Al/Zr02
Fe/Zr02
Mg/Zr02
Ca/Zr02
Na/Zr02
K/Zr02
Ti/Zr02
Mn/Zr02
More than one number indicates samples from the listed traps were combined
for analysis. Numbers in parentheses indicate samples from different
years were combined for analysis. Water and volatiles not reported.
Major oxides were calculated from elemental data in file dusticp.xls (see
file readdust.doc) using atomic weights.
Major oxides were recalculated to 100% on a water- and volatile-free
basis, assuming that the sum of percentages of major oxides and zirconium
should equal 100% of the sample.
X No data
----------------------------------------------------------------------
Files Core/raw/climate/climreg.txt
Derived/dos/climreg.xls
Variable names from Core/raw/climate/climreg.txt:
Station
Group
Elevation
MAT
MAP
number of yrs<1961
MAT before 1961
number of years1961-90
MAT from 1961-90
number of yrs<1961
MAP before 1961
number of years1961-90
MAP from 1961-90
1961 MAT records 1961 through 1990
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1961 MAP records 1961 through 1990
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
* Stations in the southern Nevada-southern California area with spotty
climatic data that had to be hand-entered by year to obtain mean
annual temperature (MAT) and mean annual precipitation (MAP) for the
period of record (see columns to right).
-- No data for the year.
----------------------------------------------------------------------
Files Core/raw/climate/aveclim.txt (all stations together)
Core/raw/climate/history/ (each station in its own file)
Derived/dos/aveclim.xls
Variable names from Core/raw/climate/aveclim.txt:
Station
Time interval
TJan
TFeb
TMar
TApr
TMay
TJun
TJul
TAug
TSep
TOct
TNov
TDec
Mean yearly temperature
PJan
PFeb
PMar
PApr
PMay
PJun
PJul
PAug
PSep
POct
PNov
PDec
Annual total precipitation
-- No data for the year.
----------------------------------------------------------------------
Files Core/raw/climate/trapclim.txt
Derived/dos/trapclim.xls
Variable names from Core/raw/climate/trapclim.txt:
Trap
Est MAT (+-1.3C)
Est MAP (cm)
s.e. MAP(cm)
Quiring est. MAP (NTS)
French est MAP (so NV)
WS nearest
WS Elevation (m)
WS MAP (cm)
Codes under geographic area refer to site groups used to calculate
regression equations of mean annual precipitation (MAP) with elevation
(see file climreg.xls).
ID Interior Desert
CR-SS Colorado River-Salton Sea
SWCA Southwestern California
Weather stations are the same as those listed in other climate files
(climreg.xls, aveclim.xls).
----------------------------------------------------------------------
Files Core/raw/climate/climate.txt
Core/raw/climate/recent/
Derived/dos/climate.xls
Variable names from Core/raw/climate/climate.txt:
Station
State
Latitude
Longitude
Elevation (m)
Time interval
TJan
TFeb
TMar
TApr
TMay
TJun
TJul
TAug
TSep
TOct
TNov
TDec
Mean annual T
PJan
PFeb
PMar
PApr
PMay
PJun
PJul
PAug
PSep
POct
PNov
PDec
Total P
PNov-Apr
PMay-Oct
-- Missing data
Blank cell indicates the value cannot be calculated.
----------------------------------------------------------------------
Files Core/raw/climate/climpet.txt
Derived/dos/climpet.xls
[Editor's note: This is a complex file that cannot easily be made readily
readable by a DBMS; I have made minimal changes to it, only standardizing
the station names so that the names appear in this file exactly as they
appear in other files in Core/.]
PET = Potential evapotranspiration
ET means evapotransiration or leaching index, in cm
LI Leaching index of Arkley (1967)
Pan Pan evaporation
thorn. based on method of Thornthwaite (1948) using data in "heat index" and "exponent a" columns
papa. based on method of Papadakis (1965)
-- Missing data