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Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993?2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions....
A model for simulating desert dust cycle was adapted and applied for a dust storm case in the southwest United States (US). This is an initial test of the model's capability as part of a future public health early warning system. The modeled meteorological fields, which drive a dust storm, were evaluated against surface and upper-air measurement data. The modeled dust fields were compared with satellite images, in situ surface PM2.5 and PM10 data, and visibility data in the areas affected by the dust event. The model predicted meteorological fields reasonably well. The modeled surface and upper-air field patterns were in agreement with the measured ones. The vertical profiles of wind, temperature, and humidity followed...
Atmospheric deposition of Hg and selected trace elements was reconstructed over the past 150 years using sediment cores collected from nine remote, high-elevation lakes in Rocky Mountain National Park in Colorado and Glacier National Park in Montana. Cores were age dated by 210Pb, and sedimentation rates were determined using the constant rate of supply model. Hg concentrations in most of the cores began to increase around 1900, reaching a peak sometime after 1980. Other trace elements, particularly Pb and Cd, showed similar post-industrial increases in lake sediments, confirming that anthropogenic contaminants are reaching remote areas of the Rocky Mountains via atmospheric transport and deposition. Preindustrial...
A statistical methodology for exploring the relationships between elevation and precipitation chemistry is outlined and illustrated. The methodology is only applicable to situations where the precipitation at two (or more) matched sites is correlated. Maximum likelihood tests are utilized, with contour ellipses of assumed bivariate log-normal distributions to assist in the interpretation. Data from 12 sites located in the southern Rocky Mountains of the U.S. were used for illustration. The results indicate differences in sulphate concentrations between airsheds, between snow and rain, and between higher and lower elevations in the Rocky Mountains. There are other approaches for investigating these issues, however,...
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During January-March of 1990 a study was conducted to determine the sources of sulfur oxides present at Canyonlands and Green River, Utah. Samples were collected at these two receptor sites and at several sites intended to characterize the chemical composition of air masses reaching the receptor sites from various geographical regions. The results of the sampling program have been given in the first paper in a series of three papers. In this paper, the concentrations of spherical aluminosilicate (SAS) particles, total fluoride, and particulate selenium, arsenic and lead are combined with meteorological data to obtain source fingerprints for the ratios of these species to SOx from the various regional sources that...
Testing re-entrained aerosol kinetic emissions from roads (TRAKER) is a vehicle-based method for measuring road dust emissions. Particulate matter is sampled in front and behind a vehicle's tire and the difference in PM concentration is related to emissions. This paper describes the most recent developments of TRAKER. The loss of particles within the inlet lines, the response of the TRAKER signal (differential PM concentration) to vehicle speed, and the relationship between the TRAKER signal and unpaved road dust PM10 emissions were examined. Losses of particles to the walls in the inlet lines were similar for the left and right inlets and were less than the inter-instrument precision for particles between 0.56...
A portable open-floored wind tunnel was used to develop threshold wind speeds over two pebble covered desert soils and a sandy agricultural soil. Published in Atmospheric Environment, volume 12, issue 12, on pages 2309 - 2313, in 1978.
Stable sulfur isotope ratios and major ions in bulk snowpack samples were monitored at a network of 52 high-elevation sites along and near the Continental Divide from 1993 to 1999. This information was collected to better define atmospheric deposition to remote areas of the Rocky Mountains and to help identify the major source regions of sulfate in winter deposition. Average annual δ34S values at individual sites ranged from +4.0 to +8.2‰ and standard deviations ranged from 0.4 to 1.6‰. The chemical composition of all samples was extremely dilute and slightly acidic; average sulfate concentrations ranged from 2.4 to 12.2 μeq l−1 and pH ranged from 4.82 to 5.70. The range of δ34S values measured in...
The composition of bulk precipitation from two high-altitude sites, established in 1971 near the Continental Divide in southwestern Colorado, has been monitored by season during the past decade. Calcium ions are the predominant cationic species; sulfate is the major anionic consitituent. Bulk precipitation major ion concentrations exhibit log-normal distributions. Representative mean and standard deviation values for the major inorganic ionic species present in bulk precipitation have been calculated for three years of consecutive seasons. Standard deviations for all species, except nitrate, are similar. For two years of data grouped into quarters, deviations from mean values fall well within the plus or minus two...
Volume-weighted mean concentrations of nitrate (NO3?), ammonium (NH4+), and sulfate (SO42?) in precipitation were compared at high-elevation sites in Colorado from 1992 to 1997 to evaluate emission source areas to the east and west of the Rocky Mountains. Precipitation chemistry was measured by two sampling methods, the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and snowpack surveys at maximum accumulation. Concentrations of NO3? and SO42? in winter precipitation were greater on the western slope of the Rockies, and concentrations of NO3? and NH4+ in summer precipitation were greater on the eastern slope. Summer concentrations in general were almost twice as high as winter concentrations....
The Rocky Mountain region of Colorado and southern Wyoming receives as much as 7 kg ha−1 yr−1 of atmospheric nitrogen (N) deposition, an amount that may have caused changes in aquatic and terrestrial life in otherwise pristine ecosystems. Results from published studies indicate a long-term increase in the rate of atmospheric N deposition during the 20th century, but data from the National Atmospheric Deposition Program and Clean Air Status and Trends Network show no region-wide increase during the past 2 decades. Nitrogen loads in atmospheric wet deposition have increased since the mid-1980s, however, at three high elevation (>3000 m) sites east of the Continental Divide in the Front Range. Much of this increase...
Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993?2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions....
During January-March of 1990 a study was conducted to determine the sources of sulfur oxides present at Canyonlands and Green River, Utah. Samples were collected at these two receptor sites and at several sites intended to characterize the chemical composition of air masses reaching the receptor sites from various geographical regions. The results of the sampling program have been given in the first paper in a series of three papers. In this paper, the concentrations of spherical aluminosilicate (SAS) particles, total fluoride, and particulate selenium, arsenic and lead are combined with meteorological data to obtain source fingerprints for the ratios of these species to SOx from the various regional sources that...
Trends in snow acidity reflect the balance between strong acid inputs and reactions with neutralizing materials. Carbonate dust can be an important contributor of buffering capacity to snow; however, its concentration in snow is difficult to quantify because it dissolves rapidly in snowmelt. In snow with neutral or acidic pH, most calcite would dissolve during sample melting if snow samples were processed using standard techniques. Here a method is described for separating particulate carbonate matter from snow. Snow samples were melted in solutions close to saturation with calcite, decreasing the dissolution rate by a factor of 100?200 compared with natural melting of snow. Particulate matter larger than 0.45 ?m...
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Measurement of the loss of semi-volatile organic compounds from particles collected with a filter is carried out by comparing the amounts collected by comparable filter pack and diffusion denuder samplers. The sorbents used to collect organic compounds in the denuder and sorbent filters must have the same efficiency for collection of all gas-phase organic compounds present. Interpretation of the data requires that the efficiency of collection of gas-phase compounds by the denuder be known. In theory this can be accomplished by determination of the deposition pattern of all organic compounds collected in the denuder, but in practice this is very difficult if the organic material consists of a wide variety of compounds....
Data on ambient particulate concentrations by size and elemental composition taken in Arizona and Utah are compared to simultaneous telephotometer measurements of standard visual range. Particulate samples were collected during the VISTTA program from 26 June to 11 July 1979, at Zilnez Mesa, Arizona, and compared to similar 24 h measurements made as part of a long term research program at Zion and Canyonlands National Parks in Utah. Samples were collected with rotating drum Multtday impactors which provide three aerodynamic size ranges; 15μm–3.5μm; 3.5μm–0.5μm, and less than 0.5/jm. Elemental composition of samples was measured using the particle induced X-ray emission (PIXE)...
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During January-March of 1990 a study was conducted to determine the sources of sulfur oxides present at Canyonlands and Green River, Utah. Samples were collected at these two receptor sites and at several sites intended to characterize the chemical composition of air masses reaching the receptor sites from various geographical regions. The results of the sampling program have been given in the first paper in a series of three papers. In this paper, the concentrations of spherical aluminosilicate (SAS) particles, total fluoride, and particulate selenium, arsenic and lead are combined with meteorological data to obtain source fingerprints for the ratios of these species to SOx from the various regional sources that...
Depth-integrated snowpack chemistry was measured just prior to maximum snowpack depth during the winters of 1992?1999 at 12 sites co-located with National Atmospheric Deposition Program/National Trend Network (NADP/NTN) sites in the central and southern Rocky Mountains, USA. Winter volume-weighted mean wet-deposition concentrations were calculated for the NADP/NTN sites, and the data were compared to snowpack concentrations using the paired t-test and the Wilcoxon signed-rank test. No statistically significant differences were indicated in concentrations of SO42? or NO3? (p>0.1). Small, but statistically significant differences (p0.03) were indicated for all other solutes analyzed. Differences were largest for Ca2+...
Testing re-entrained aerosol kinetic emissions from roads (TRAKER) is a vehicle-based method for measuring road dust emissions. Particulate matter is sampled in front and behind a vehicle's tire and the difference in PM concentration is related to emissions. This paper describes the most recent developments of TRAKER. The loss of particles within the inlet lines, the response of the TRAKER signal (differential PM concentration) to vehicle speed, and the relationship between the TRAKER signal and unpaved road dust PM10 emissions were examined. Losses of particles to the walls in the inlet lines were similar for the left and right inlets and were less than the inter-instrument precision for particles between 0.56...
Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993–2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions....
map background search result map search result map Apportionment of sulfur oxides at Canyonlands during the winter of 1990 — II. fingerprints of emissions from point and regional sources impacting canyonlands Apportionment of sulfur oxides at Canyonlands during the winter of 1990— I. study design and particulate chemical composition A multiple-system, multi-channel diffusion denuder sampler for the determination of fine-particulate organic material in the atmosphere A multiple-system, multi-channel diffusion denuder sampler for the determination of fine-particulate organic material in the atmosphere Apportionment of sulfur oxides at Canyonlands during the winter of 1990 — II. fingerprints of emissions from point and regional sources impacting canyonlands Apportionment of sulfur oxides at Canyonlands during the winter of 1990— I. study design and particulate chemical composition