Aeolian modification of moraine soils,Whiskey Basin,Wyoming, USA

Soils along catenas of Pinedale (15–20 ka) and Bull Lake (100–130 ka) age moraines at Whiskey Basin in the Wind River Range, Wyoming, USA, were sampled to assess the effects of aeolian processes on soil development here. Aeolian processes appear to have in?uenced soils by both depositing sediments and eroding topsoils. Pedogenic silt (often used as an indicator of wind deposition) accumulated in the Bull Lake soils moderately correlate with pedogenic clay accumulated, suggesting that ?ne sediments may have been deposited and incorporated into soil formation here. Following removal of previous topsoil by wind during Pinedale glaciation, Bull Lake B horizons have developed into contemporary A horizons. These data further link aeolian processes to soil development on piedmont moraines throughout the Wind River Range. Copyright © 2004 John Wiley & Sons, Ltd.     

Direct observation of heavy metal-mineral association from the Clark Fork River Superfund Complex: Implications for metal transport and bioavailability

Two sets of samples from riverbeds and adjacent floodplains, separated by 80 river kilometers, were collected from the Clark Fork River Superfund Complex, Montana, (the largest Superfund site in the United States), and studied primarily with transmission electron microscopy (TEM) with several supporting techniques to determine heavy metal-mineral association. Seven of the eight samples studied were strongly influenced by material that once resided in mining and smelting dumps and impoundments; this material was transported downstream sometime during the last century and a half from the Butte/Anaconda areas. The eighth sample was from a deeper floodplain level and dates to premining days. The TEM observations afford a direct look, down to the nanometer level, at secondary mineral formation as a result of the breakdown of sulfides and silicates in the acid environment of this massive mine-drainage system. In the shallow, oxic floodplain sediments, heavy metals of concern in this system (As, Cu, Pb, and Zn) are taken up by the formation of sulfates (particularly Pb in jarosite), as well as hydrous metal oxides (As, Cu, Pb, and Zn in and on ferrihydrite, and a possibly new vernadite-like mineral). The oxides are long-lived in these systems, as they were also found in the anoxic riverbeds. Metals are also taken up by the formation of sulfides in sulfate-reducing environments as observed in the formation of nanoclusters of chalcopyrite and sphalerite. In all samples, clays make up between 5 and 20% of the sediment and carry significant amounts of Cu and Zn. The hydrous oxides, secondary sulfides, and clays provide several routes for metal transport downstream over long distances. Besides the potential bioavailability of heavy metals exchanged on and off the hydrous metal oxides and clays, nanometer-sized sulfides may also be highly reactive in the presence of biologic systems.     

Impacts of land use and fire on the loss and degradation of lowland forest in 1983–2000 in East Kutai District, East Kalimantan, Indonesia

Deforestation and forest degradation are proceeding rapidly in the lowland forests of Indonesian Borneo. Time series analysis of satellite imagery provides an ideal means of quantifying landscape change and identifying the pathways which lead to the changes. This study investigates the forest and land cover changes by classifying Landsat MSS (Multispectral Scanner), TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) images over three time periods (1983–90, 1990–98, and 1998–2000), creating land cover maps for each year and change trajectories for each year-pair. The study area chosen covers an area of 2160 km² of undulating topography and alluvial plains in the East Kutai District of East Kalimantan Province, which in the 1980s was covered mostly with lowland dipterocarp forest; today the landscape is a patchwork dominated by oil palm and timber plantations and degraded forest. We relate land cover change data to land use allocation and to fire impacts based on fire hotspot distribution and fire damage information. The multidate land cover change trajectories provide an insight into the forest loss and degradation pathways over the 17-year period spanning the first entry of commercial logging concessionaires, followed by a government-sponsored transmigration scheme, government-licensed timber and oil palm plantations and, finally, the devastating fires of 1998. The results show a mean deforestation rate of 42 km² or 6 per cent per year for 1983–2000, rising to 10 per cent per year for 1990–98; by 2000, 70 per cent of forest initially damaged by fire and drought during the 1982–83 El Niño event was classified as non-forest. Although our study area is perhaps a worst-case scenario in terms of land use planning outcomes, the lessons from this research are directly applicable to scenario prediction for informed forest and land use planning and monitoring.     

Morphology and stratigraphy of the late Quaternary lower Brazos valley: Implications for paleo-climate, discharge and sediment delivery

A shallow coring and geophysical logging program has recorded the sedimentary fill of the Brazos River valley in the Texas Gulf Coastal Plain. Thermoluminescence dates together with new and recalibrated published radiocarbon dates show the valley fill to include extensive, sandy, buried falling stage and lowstand Oxygen Isotope Stage (OIS) 3 and 2 deposits. These alluvial deposits are punctuated by numerous paleosoil horizons that record alternating periods of cutting, bypass and accumulation. Maximum valley incision and two periods of terrace formation preceded marine lowstand conditions, suggesting significant discordance between preserved fluvial and classical marine system tracts. The latest Pleistocene incision and fill history appears related to cycles of increased discharge and incision, followed by system equilibration and terrace formation. Analysis of the Brazos River incised valley and its contained paleochannels indicates that latest Pleistocene mean annual discharge was as much as four times greater than that of today. This magnitude of discharge in the Brazos would require a two-fold increase in precipitation across the drainage basin. Such an increase is comparable to the present day measured positive El Niño winter precipitation anomaly across the region. Paleochannel geometries and the stratigraphic and sedimentologic data from this investigation support the hypothesis that periods of high-amplitude, El Niño-like climatic perturbations characterized the late Quaternary climate of the south-central and southwestern U.S. This period of high discharge coincides, at least in part, with late OIS 3 progradation of the Brazos delta to the shelf margin, OIS 3 and 2 valley incision across the Texas shelf, and concomitant sand bypass to intraslope basins beyond the shelf edge.     

Embracing cultural geography: an army imperative

As an instrument of national strategy, the United States Army has served the American people well for more than two centuries. Its fundamental mission has always been to fight and win America's Wars. As we have moved from the bi-polar nature of world dynamics to that of the new global neighborhood, the American Army has seen an increase in missions related to peacekeeping, disaster relief, and humanitarian actions. From a geography perspective, the Army must operate in numerous countries simultaneously. To succeed, the Army must go beyond physical accomplishments: it must interact and communicate with nations at a level of shared understanding and enthusiasm of each others culture. The American soldier must understand the cultural nature of geography as well as the physical. The hypothesis of this paper is: There is an urgent need for the men and women of the Unites States Army to have a firm conviction that people of other cultures have beliefs, value systems, and customs that result in behaviors and perceptions that may be vastly different than ours. . .and that those differences are legitimate. Beginning with mistakes made during the Vietnam war, the authors give examples, current as well as past, of cultural illiteracy on the part of the military. The role of the Army in the new world order is then addressed with emphasis on the types of missions to be expected in the 21^st Century. The authors point out that significant efforts to grasp customs of foreign countries to which Army units are deployed have been made during recent years; however, much remains to be accomplished. The solution to a lack of cultural awareness is given in the form of improvements to the Army military education system. An overview of the current training environment, with its strengths and weaknesses, is provided as a precursor to recommendations for future training. A multitiered education system is proposed in which cultural awareness education is provided at all levels of authority, from the basic training recruit to senior officers. Given that programs of instruction are already full, it will take a combination of command emphasis and innovation to accomplish the goal of inculcating cultural awareness in the American Army. The paper concludes with the position that the only way the Army can accomplish its changed global missions is by first winning its own war against cultural illiteracy.     

An experimental study of the diffusion of oxygen in quartz and albite using an overgrowth technique

Diffusion rates of¹⁸O tracer in quartz ( c, 1 Kb H₂O) and Amelia albite ( 001, 2 Kb H₂O) have been measured, using Secondary Ion Mass Spectrometry (SIMS). A new technique involving hydrothermal deposition of labelled materials has removed the possibility of pressure solution-reprecipitation processes adversely affecting the experiments. Reported diffusion constants are:-quartz ( c), ,Q=98±7 KJ mol^–1 (600–825° C, 1 Kb); Amelia albite ( 001), ,Q=85±7 KJ mol^–1, (400–600° C, 2 Kb). Measured quartz¹⁸O diffusivities decrease discontinuously at the- transition, reflecting strong structural influences. The reported albite data agree with previously recorded studies, but-quartz data indicate significantly lower activation energies. Possible causes of this discrepancy, and some geological consequences, are noted.     

Nitrate in the atmospheric boundary layer of the tropical South Pacific: Implications regarding sources and transport

Weekly bulk aerosol samples collected at Funafuti, Tuvalu (8°30S, 179°12E), American Samoa (14°15S, 170°35W), and Rarotonga (21°15S, 159°45W), from 1983 through most of 1987 have been analyzed for nitrate and other constituents. The mean nitrate concentration is about 0.11 g m^–3 at each of these stations: 0.107±0.011 g m^–3 at Funafuti; 0.116±0.008 at American Samoa; and 0.117±0.010 at Rarotonga. Previous measurements of mineral aerosol and trace metal concentrations at American Samoa are among the lowest ever recorded for the near-surface troposphere and indicate that this region is minimally affected by transport of soil material and pollutants from the continents. Consequently, the nitrate concentration of 0.11 g m^–3 can be regarded as the natural level for the remote marine boundary layer of the tropical South Pacific Ocean. In contrast, over the tropical North Pacific which is significantly impacted by the transport of material from Asia and North America, the mean nitrate concentrations are about three times higher, 0.29 and 0.36 g m^–3 at Midway and Oahu, respectively. The major sources of the nitrate over the tropical South Pacific are still very uncertain. A very significant correlation between the nitrate concentrations at American Samoa and the concentrations of ²¹⁰Pb suggests that transport from continental sources might be important. This continental source could be lightning, which occurs most frequently over the tropical continents. A near-zero correlation with ⁷Be indicates that the stratosphere and upper troposphere are probably not the major sources. A significant biogenic source would be consistent with the higher mean nitrate concentrations, 0.16 to 0.17 g m^–3, found over the equatorial Pacific at Fanning Island (3°55N, 159°20W) and Nauru (0°32S, 166°57E). The lack of correlation between nitrate and nss sulfate at American Samoa does not necessarily preclude an important role for marine biogenic sources.     

The effect of temperature and food density on survival and growth of Menidia peninsulae larvae (Pisces: Atherinidae)

Day of hatch tidewater silversides, Menidia peninsulae, were stocked at 5 fish per liter in 3 1 of seawater at 30‰ and raised for 16 days at 20°, 25° and 30 °C. Food organisms (Brachionus sp. or Artemia nauplii) were maintained at 500, 1,000, 5,000 or 10,000 organisms per 1. The influence of food density on growth of larval M. peninsulae was temperature dependent. At 20 °C, there was no difference in final size of fish based on food densities. But at 25° and 30 °C there was an increase in final body size as food density increased. There were no significant differences in survival among food densities in tests at 20°, 25° or 30 °C. However, for any given temperature and food density, the number of survivors in a replicate affected the final size attained. Optimal culture condition for larval M. peninsulae, considering both survival and growth was determined to be 5,000 food organisms per 1 at 25 °C.