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Temporal and spatial sources of silica for chert remain poorly constrained. Modern sources to the worlds oceans include silica in rivers > aeolian (dust) deposition > sea floor vents and submarine weathering. However, changes in aridity and dust flux during the Phanerozoic may explain variations in the ocean silica cycle and times and places of chert formation. The chemistry of fine quartz dust (FQD) provides a chemical mechanism for the transformation of FQD to polymorphs of silica in chert; FQD is readily dissolved, then reprecipitated as Opal-A by either biotic or abiotic processes. An unequivocal relation between increases in dust flux and biogenic opal-A in the western Pacific Ocean during the past 200 kyr...
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The health of soils along roadways is critical for maximizing habitat quality and minimizing negative ecological effects of roads. Adjacent to unpaved roads, soil chemistry may be altered by the deposition of dust, as well as by road treatment with dust suppressants or soil stabilizer products. If present in roadside soils, these product residues may be available to plants, terrestrial invertebrates, or small mammals. Unfortunately, very few studies have attempted to track the transport of dust suppressants after application. As part of a larger ongoing study on the environmental effects of dust suppressant products on roadside plants and animals, we sampled roadside soils at Squaw Creek National Wildlife Refuge...
Ecosystem disturbances that remove vegetation and disturb surface soils are major causes of excessive soil erosion and can result in accelerated transport of soils contaminated with hazardous materials. Accelerated wind erosion in disturbed lands that are contaminated is of particular concern because of potential increased inhalation exposure, yet measurements regarding these relationships are lacking. The importance of this was highlighted when, in May of 2000, the Cerro Grande fire burned over roughly 30% of Los Alamos National Laboratory (LANL), mostly in ponderosa pine (Pinus ponderosa) forest, and through areas with soils containing contaminants, particularly excess depleted and natural uranium. Additionally,...
Deposition of suspended dust near eroding source fields can have detrimental effects on vegetation, as well as on soil and water quality. This study was undertaken to quantify dust deposition within 200 m of a source field during wind erosion events. Erosion was measured with BSNE samplers on a small field of Amarillo fine sandy loam at field at Big Spring, TX. Suspension-sized dust discharge averaged 33 � 5 per cent of the total sediment discharge and ranged from 18�0 to 147�4 kg m?1 during eight selected storm events. Within 200 m of the source field boundary, dust collected in deposition samplers placed above a vegetated surface averaged 34 per cent of initial dust discharge. Predicted deposition, according to...
The recent upsurge in research attention to aeolian dust has shown that dust transport systems operate on very large spatial and temporal scales, and involve much larger quantities of sediment than was previously realized. An inevitable consequence of this is that researchers from a range of neighbouring disciplines, including ecology, are beginning to realize that this new knowledge has important implications for their study areas. In the present paper, we examine the ecological implications (real and potential) of this expanding knowledge of dust transport systems, with a particular emphasis upon the Australian dust transport system. We track these ecological effects from source to sink. At source, wind erosion–soil–vegetation...
The aeolian accumulation of natural atmospheric dust in a desert environment was investigated during a 24-month experiment. Accumulation was measured with marble collectors every month. At the same time, wind speed, dust concentration, dew formation and rainfall were recorded. Atmospheric stability was measured from a 90 m tower several km from the test site. Dust accumulation by day was systematically higher than dust accumulation at night. Also, dust concentration was higher, but the higher concentrations cannot completely explain die higher accumulation values. Both average monthly concentration and accumulation are considerably influenced by the occurrence of high-magnitude dust events, either dust storms or...
This interactive workshop was designed to provide background information and stimulate discussion on the effects of climate variability, possible natural and human-related long-term climate change, and land-use change in the rapidly-growing southwestern United States. This information will be used by the U.S. Global Change Research Program as part of a national assessment of Global Change issues. This web conference was open for interactive participation from Monday, July 7 through Friday, July 25, 1997. The articles and comments will remain available indefinitely.


map background search result map search result map Soil chemistry adjacent to roads treated with dust control products at Squaw Creek National Wildlife Refuge The chemistry of eolian quartz dust and the origin of chert Soil chemistry adjacent to roads treated with dust control products at Squaw Creek National Wildlife Refuge The chemistry of eolian quartz dust and the origin of chert