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New Mexico (new + mexico)
Selected AbstractsMutant Ecologies: Radioactive Life in Post,Cold War New MexicoCULTURAL ANTHROPOLOGY, Issue 4 2004Joseph Masco A political ecology of the nuclear age developed through a theorization of "mutation" interrogates the contemporary terms of radioactive nature in New Mexico. As an analytic, the value of "mutation" is its emphasis on multigenerational effects, enabling an assessment of biosocial transformations as, alternatively, injury, improvement, or noise. Cold War radiation experiments, the post,Cold War transformation of nuclear production sites into "wildlife reserves," and the expanding role that biological beings play as "environmental sentinels" in New Mexico are all sites where concerns about "species" integrity may be articulated in relation to radioactive nature. [source] Trends in Pediatric Melanoma Mortality in the United States, 1968 through 2004DERMATOLOGIC SURGERY, Issue 2 2008KEVAN G. LEWIS MD BACKGROUND AND OBJECTIVE Mortality from melanoma in children is a poorly understood and controversial problem in dermatology. There is paucity of research into this important public health dilemma. The purpose of this study was to characterize pediatric melanoma mortality in the United States and to evaluate trends over time. METHODS AND MATERIALS Deaths were derived from a database of more than 75 million records of the U.S. Center for National Health Statistics based on routine death certification. Information on age, race, gender, and geographic location was available for years 1968 through 2004. RESULTS During the 37-year period, there were 643 deaths attributed to melanoma in children under 20 years of age in the United States, an average of 18 per year. The overall age-adjusted mortality rate for melanoma in children was 2.25 deaths per year (per 10 million at-risk individuals). Mortality rates were strongly associated with age. In the oldest age group (age 15,19 years) the mortality rate was approximately an order of magnitude 8,18 times higher compared to younger age groups. Mortality among males was 25% higher than females. Mortality rates for white children were more than twice as high as black children. Overall mortality from melanoma in children declined steadily from 1968 to 2004. The highest mortality rates were observed in Idaho, Nevada, Arizona, and New Mexico. CONCLUSIONS Although mortality from melanoma among children in the United State is low, the magnitude of the public health burden from this preventable cause of death is substantial. In contrast to results of studies suggesting that the incidence of melanoma may be rising in children and adolescents, the data suggest that mortality in these groups may be falling. Additional study is warranted to further characterize and ultimately reduce mortality from childhood melanoma. [source] Spread and current potential distribution of an alien grass, Eragrostis lehmanniana Nees, in the southwestern USA: comparing historical data and ecological niche modelsDIVERSITY AND DISTRIBUTIONS, Issue 5 2006Heather Schussman ABSTRACT The potential distribution of alien species in a novel habitat often is difficult to predict because factors limiting species distributions may be unique to the new locale. Eragrostis lehmanniana is a perennial grass purposely introduced from South Africa to Arizona, USA in the 1930s; by the 1980s, it had doubled its extent. Based on environmental characteristics associated with its introduced and native range, researchers believed that E. lehmanniana had reached the limits of its distribution by the early 1990s. We collected data on E. lehmanniana locations from various land management agencies throughout Arizona and western New Mexico and found new records that indicate that E. lehmanniana has continued to spread. Also, we employed two modelling techniques to determine the current potential distribution and to re-investigate several environmental variables related to distribution. Precipitation and temperature regimes similar to those indicated by past research were the most important variables influencing model output. The potential distribution of E. lehmanniana mapped by both models was 71,843 km2 and covers a large portion of southeastern and central Arizona. Logistic regression (LR) predicted a potential distribution of E. lehmanniana more similar to this species current distribution than GARP based on average temperature, precipitation, and grassland species composition and recorded occurrences. Results of a cross-validation assessment and extrinsic testing showed that the LR model performed as well or better than GARP based on sensitivity, specificity, and kappa indices. [source] A new platysomid from the Upper Carboniferous of Kansas (USA) and remarks on the systematics of deep-bodied lower actinopterygiansACTA ZOOLOGICA, Issue 2009Kathryn E. Mickle Abstract Scales and presumptive tooth plates from deep-bodied platysomid actinopterygians have previously been reported from the Lower Permian of Kansas (USA), but until now, an articulated specimen from this state has not been recovered. The first articulated deep-bodied platysomid fish from the Upper Carboniferous of Kansas is described herein. This specimen is compared to other known species from the genus Platysomus, with special attention paid to the North American taxa. The cranial osteology of this new specimen is closest to Platysomus schultzei from the Upper Carboniferous of New Mexico. The newly described platysomid species highlights the need for a revision of the fish included within the genus Platysomus. [source] Biogeographic variation in nest placement: a case study with conservation implicationsDIVERSITY AND DISTRIBUTIONS, Issue 1 2002Jennifer M. Parody Abstract. Local habitat characteristics are often used to describe a species' niche despite the fact that habitat use can vary across the geographical range. We sought to quantify variation in habitat preferences by asking how nesting habit varies within and between populations of Bell's vireo (Vireo bellii) across its geographical range. Analyses of detailed nest placement data from three localities (Kansas, eastern New Mexico and western New Mexico) showed a general trend towards use of dense vegetation. However, there was substantial variation in nest placement and vegetation at nest sites between localities. Furthermore, a review of nest placement data from the literature shows strong differences in nest heights and species of trees even between populations less than 100 km apart. We evaluate these results in light of conservation and suggest that to be most effective, habitat conservation plans should be based on data collected at the locality where the population of interest occurs. [source] Dating floodplain sediments using tree-ring response to burial,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2005Jonathan M. Friedman Abstract Floodplain sediments can be dated precisely based on the change in anatomy of tree rings upon burial. When a stem of tamarisk (Tamarix ramosissima) or sandbar willow (Salix exigua) is buried, subsequent annual rings in the buried section resemble the rings of roots: rings become narrower, vessels within the rings become larger, and transitions between rings become less distinct. We combined observations of these changes with tree-ring counts to determine the year of deposition of sedimentary beds exposed in a 150-m-long trench across the floodplain of the Rio Puerco, a rapidly filling arroyo in New Mexico. This method reliably dated most beds thicker than about 30 cm to within a year of deposition. Floodplain aggradation rates varied dramatically through time and space. Sediment deposition was mostly limited to brief overbank flows occurring every few years. The most rapid deposition occurred on channel-margin levees, which migrated laterally during channel narrowing. At the decadal timescale, the cross-section-average sediment deposition rate was steady, but there was a shift in the spatial pattern of deposition in the 1980s. From 1936 to 1986, sediment deposition occurred by channel narrowing, with little change in elevation of the thalweg. After 1986 sediment deposition occurred by vertical aggradation. From 1936 to 2000 about 27 per cent of the arroyo cross-section filled with sediment. The rate of filling from 1962 to 2000 was 0·8 vertical m/decade or 85 m2/decade. Published in 2005 by John Wiley & Sons, Ltd. [source] Ecohydrological controls on snowmelt partitioning in mixed-conifer sub-alpine forestsECOHYDROLOGY, Issue 2 2009Noah P. Molotch Abstract We used co-located observations of snow depth, soil temperature, and moisture and energy fluxes to monitor variability in snowmelt infiltration and vegetation water use at mixed-conifer sub-alpine forest sites in the Valles Caldera, New Mexico (3020 m) and on Niwot Ridge, Colorado (3050 m). At both sites, vegetation structure largely controlled the distribution of snow accumulation with 29% greater accumulation in open versus under-canopy locations. Snow ablation rates were diminished by 39% in under-canopy locations, indicating increases in vegetation density act to extend the duration of the snowmelt season. Similarly, differences in climate altered snow-season duration, snowmelt infiltration and evapotranspiration. Commencement of the growing season was coincident with melt-water input to the soil and lagged behind springtime increases in air temperature by 12 days on average, ranging from 2 to 33 days under warmer and colder conditions, respectively. Similarly, the timing of peak soil moisture was highly variable, lagging behind springtime increases in air temperature by 42 and 31 days on average at the Colorado and New Mexico sites, respectively. Latent heat flux and associated evaporative loss to the atmosphere was 28% greater for the year with earlier onset of snowmelt infiltration. Given the large and variable fraction of precipitation that was partitioned into water vapour loss, the combined effects of changes in vegetation structure, climate and associated changes to the timing and magnitude of snowmelt may have large effects on the partitioning of snowmelt into evapotranspiration, surface runoff and ground water recharge. Copyright © 2009 John Wiley & Sons, Ltd. [source] Comparison of soil moisture and meteorological controls on pine and spruce transpirationECOHYDROLOGY, Issue 3 2008Eric E. Small Abstract Transpiration is an important component of the water balance in the high elevation headwaters of semi-arid drainage basins. We compare the importance of soil moisture and meteorological controls on transpiration and quantify how these controls are different at a ponderosa pine site and a spruce site in the Jemez river drainage basin of northern New Mexico, a sub-basin of the Rio Grande. If only soil moisture controls fluctuations in transpiration, then simple hydrologic models focussed only on soil moisture limitations are reasonable for water balance studies. If meteorological controls are also critical, then more complex models are required. We measured volumetric water content in the soil and sap velocity, and assumed that transpiration is proportional to sap velocity. Ponderosa sap velocity varies with root zone soil moisture. Nearly all of the scatter in the ponderosa sap velocity,soil moisture relationship can be predicted using a simple model of potential evapotranspiration (ET), which depends only on measured incident radiation and air temperature. Therefore, simple hydrologic models of ponderosa pine transpiration are warranted. In contrast, spruce sap velocity does not clearly covary with soil moisture. Including variations in potential evapotranspiration does not clarify the relationship between sap velocity and soil moisture. Likewise, variations in radiation, air temperature, and vapour pressure do not explain the observed fluctuations in sap velocity, at least according to the standard models and parameters for meteorological restrictions on transpiration. Both the simple and more complex models commonly used to predict transpiration are not adequate to model the water balance in the spruce forest studied here. Copyright © 2008 John Wiley & Sons, Ltd. [source] Spatial variability of soil and nutrient characteristics of semi-arid grasslands and shrublands, Jornada Basin, New MexicoECOHYDROLOGY, Issue 1 2008Eva Nora Mueller Abstract Heterogeneity of vegetation and soil properties is characteristic of semi-arid and arid environments. The potential underlying causes of the dynamics that create this spatial variability, with consequent impacts on landscape connectivity and thus ecological and ecohydrological processes, are not clearly understood. An investigation was carried out into the spatial variability of ponded infiltration rate, soil moisture, soil-aggregate stability, vegetation cover, random roughness and nutrient content in the soil (ammonium, nitrate and phosphorus) at grassland and shrubland sites for two spatial scales in the Jornada Basin, in the northern part of the Chihuahua desert. At the plant-interplant scale, statistically significant differences exist between vegetated and non-vegetated sites for soil moisture and infiltration rate within both shrublands and grasslands. The spatial distributions of all other parameters follow a more complex scheme at this scale. At the landscape scale, distinct differences exist for most parameters between the grasslands and the shrubland sites. Geostatistical analysis revealed that the autocorrelation lengths are not simply a function of average shrub sizes, but may be caused by a more complex pattern probably related to the spatial layout of rill and inter-rill areas and other localized transfers of soil resources through the redistribution of water and wind. These results demonstrate the importance of understanding spatial linkages of processes within the landscape in understanding dryland ecosystem dynamics. Copyright © 2007 John Wiley & Sons, Ltd. [source] Multiple influences of nitrate on uranium solubility during bioremediation of uranium-contaminated subsurface sedimentsENVIRONMENTAL MICROBIOLOGY, Issue 9 2002Kevin T. Finneran Summary Microbiological reduction of soluble U(VI) to insoluble U(IV) has been proposed as a remediation strategy for uranium-contaminated groundwater. Nitrate is a common co-contaminant with uranium. Nitrate inhibited U(VI) reduction in acetate-amended aquifer sediments collected from a uranium-contaminated site in New Mexico. Once nitrate was depleted, both U(VI) and Fe(III) were reduced concurrently. When nitrate was added to sediments in which U(VI) had been reduced, U(VI) reappeared in solution. Parallel studies with the dissimilatory Fe(III)-, U(VI)- and nitrate-reducing microorganism, Geobacter metallireducens, demonstrated that nitrate inhibited reduction of Fe(III) and U(VI) in cell suspensions of cells that had been grown with nitrate as the electron acceptor, but not in Fe(III)-grown cells. Suspensions of nitrate-grown G. metallireducens oxidized Fe(II) and U(IV) with nitrate as the electron acceptor. U(IV) oxidation was accelerated when Fe(II) was also added, presumably due to the Fe(III) being formed abiotically oxidizing U(IV). These studies demonstrate that although the presence of nitrate is not likely to be an impediment to the bioremediation of uranium contamination with microbial U(VI) reduction, it is necessary to reduce nitrate before U(VI) can be reduced. These results also suggest that anaerobic oxidation of U(IV) to U(VI) with nitrate serving as the electron acceptor may provide a novel strategy for solubilizing and extracting microbial U(IV) precipitates from the subsurface. [source] Unintentional drug overdose death trends in New Mexico, USA, 1990,2005: combinations of heroin, cocaine, prescription opioids and alcoholADDICTION, Issue 1 2008Nina G. Shah ABSTRACT Aims To determine the contribution of heroin, prescription opioids, cocaine and alcohol/drug combinations to the total overdose death rate and identify changes in drug overdose patterns among New Mexico subpopulations. Design We analyzed medical examiner data for all unintentional drug overdose deaths in New Mexico during 1990,2005. Age-adjusted drug overdose death rates were calculated by sex and race/ethnicity; we modeled overall drug overdose death adjusting for age and region. Findings The total unintentional drug overdose death rate in New Mexico increased from 5.6 per 100 000 in 1990 to 15.5 per 100 000 in 2005. Deaths caused by heroin, prescription opioids, cocaine and alcohol/drug combinations together ranged from 89% to 98% of the total. Heroin caused the most deaths during 1990,2005, with a notable rate increase in prescription opioid overdose death during 1998,2005 (58%). During 1990,2005, the 196% increase in single drug category overdose death was driven by prescription opioids alone and heroin alone; the 148% increase in multi-drug category overdose death was driven by heroin/alcohol and heroin/cocaine. Hispanic males had the highest overdose death rate, followed by white males, white females, Hispanic females and American Indians. The most common categories causing death were heroin alone and heroin/alcohol among Hispanic males, heroin/alcohol among American Indian males and prescription opioids alone among white males and all female subpopulations. Conclusions Interventions to prevent drug overdose death should be targeted according to use patterns among at-risk subpopulations. A comprehensive approach addressing both illicit and prescription drug users, and people who use these drugs concurrently, is needed to reduce overdose death. [source] Unintentional methadone-related overdose death in New Mexico (USA) and implications for surveillance, 1998,2002ADDICTION, Issue 2 2005Nina Shah ABSTRACT Aims To determine death rates from methadone over time, to characterize methadone-related death and to discuss public health surveillance of methadone-related death. Design We analyzed medical examiner data for all unintentional drug overdose deaths in New Mexico, USA, between 1998 and 2002. Measurements Age-adjusted death rates for methadone-related death, logistic regression models for likelihood of methadone-related death among all unintentional drug overdose deaths and bivariate comparisons within methadone-related death. Findings Of 1120 drug overdose deaths during this period, there were 143 (12.8%) methadone-related deaths; the death rate decreased over the time period, averaging 1.6 per 100 000. Of 143 methadone-related deaths, 22.4% were due to methadone alone, 23.8% were due to methadone/prescription drugs (no illicit drugs), 50.3% were due to methadone/illicit drugs and 3.5% were due to methadone/alcohol. These groups were significantly different in demographics, health history and circumstances of death. Of 79 decedents (55.2%) with a known source of methadone, 68 obtained methadone through a physician prescription (31 for methadone maintenance treatment (MMT), 27 for managing pain and 10 had unknown reason for prescription). Conclusions Methadone-related death rates and the proportion of methadone-related death among all drug overdose deaths decreased in New Mexico from 1998 to 2002. It is important for surveillance of methadone-related death to assess multiple drug causes, not just underlying cause. Also, methadone for pain management must be examined alongside MMT and when possible, methadone co-intoxication should be described in the context of other drugs causing death. [source] New Mexico's 1998 drive-up liquor window closure.ADDICTION, Issue 5 2004Study I: effect on alcohol-involved crashes ABSTRACT Aims To determine the spatial relationship between drive-up liquor window locations and alcohol-related traffic crashes for 2 years before and after New Mexico banned drive-through alcohol sales. Design Current liquor licenses, crash data, roadway information and US Census data were used in this analysis. Cross-sectional and longitudinal regression analyses were applied to the entire state, and to Albuquerque only. Findings Of all NM liquor licenses, 189 (9%) included drive-up sales, which co-occurred with on- or off-premise licenses (94%). The rate of non-pedestrian alcohol-related crashes relative to non-pedestrian total crashes showed an increasing trend prior to closure and a decreasing trend after the closure. Cross-sectional analyses in Albuquerque revealed that the percentage of alcohol-involved crashes was not related to densities of on- or off-premise outlets per kilometer of roadway, or to percentage of drive-up outlets. Statewide, the percentage of drive-up outlets was not significantly related to the percentage of alcohol-related crashes within census tracts but was associated positively with the percentage of alcohol-related crashes in surrounding census tracts. There was no statistically significant relationship between number of drive-ups and percentage of alcohol-related crashes in either longitudinal model. Conclusions Despite the declining rate of alcohol-related crashes following closure of drive-up liquor windows, both in Albuquerque and statewide, regression models using spatial data do not demonstrate definitively an association between the decline and the closure of the drive-up liquor windows. [source] Female Choice by Scent Recognition in the Spotted Cucumber BeetleETHOLOGY, Issue 3 2006Jeremy F. Brodt In species that demonstrate female choice, geographically distinct populations can vary in their signal-response behaviors as a result of environmental differences or genetic drift. Observing whether or not females discriminate against males from allopatric populations can establish such signal deviations. Here we compare mating success within and between populations of the spotted cucumber beetle (Diabrotica undecimpunctata howardi) collected from Delaware, Tennessee, Missouri, and New Mexico, USA. A no-choice cross-mating experiment was employed to measure female preference for sympatric and allopatric males. While only two of the populations (Tennessee and Missouri) demonstrated statistically significant female preference for sympatric males, this trend was observed in all populations tested. Further, we show that (i) males from Tennessee, Missouri, and New Mexico differ in their scent, (ii) females may use population-specific scents to discriminate among males, and (iii) females whose antennae have been surgically removed are unable to recognize acceptable mates. New Mexico males, which were never accepted by either Tennessee or Missouri females, became acceptable mates when crowded with Tennessee or Missouri males prior to copulation. We infer that male odor may be an important factor in determining cucumber beetle mating success. [source] Single and multigrain quartz-luminescence dating of irrigation-channel features in Santa Fe, New MexicoGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2009Glenn W. Berger Acequias (irrigation channels and ditches) were used by Spanish settlers, their descendants, and Native Americans in New Mexico. Several such features were recently excavated in Santa Fe, but material for numeric dating was difficult to find. Therefore, for this high-energy-deposition irrigation-feature setting we applied optically stimulated luminescence (OSL) sediment dating methods to determine the timing of last filling of some of these acequias. We report multigrain single-aliquot quartz (MGSAQ) OSL dating results and the first single-grain quartz (SGQ) OSL dating results for irrigation features. One sample yielded an average age of 96 ± 13 yr, consistent with the maximum expected age of 127 yr (before 2007). An OSL age of 175 ± 15 yr for another sample delimits a sedimentation event since the first construction of that feature ca. 300 yr ago. A sample known to be younger than 400,450 yr but predating the mid-19th century gave an SGQ age of 376 ±31 yr. These results indicate that: (1) Regional quartz in New Mexico is highly favorable to OSL dating; (2) in this setting, SGQ OSL dating is preferred to MGSAQ dating; and (3) for the last 500,600 yr, SGQ OSL dating in such settings is preferred to 14C dating because OSL dating lacks those ambiguities inherent in converting 14C ages to calendar years. © 2009 Wiley Periodicals, Inc. [source] Analysis of adobe wall composition at the Chaves-Hummingbird Site, New Mexico, by diffuse reflectance spectrophotometryGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2007William Balsam This article investigates adobe wall construction materials utilized by prehistoric inhabitants of Chaves-Hummingbird Pueblo, an ancestral Pueblo village located ,20 miles west of Albuquerque, New Mexico. The walls were constructed with native clay-rich soils some time between approximately 1275,1450 A.D. Samples were analyzed with a diffuse reflectance spectrophotometer from the near ultraviolet (NUV) through the visible (VIS) and into the near infrared (NIR) region of the electromagnetic spectrum. Cluster analysis of samples from 275 adobe walls and 36 soil locations surrounding the pueblo room blocks indicates four clusters. Comparison of typical samples from the four clusters indicates that they are very similar and are distinguished by minor variations in the three primary spectrally determined components, Na-Ca montmorillonite, bentonite, and goethite. In general, clusters correspond with room construction episodes that are discernible through patterns of wall bonding and abutment recorded during the archaeological investigation of the site. This suggests that during different phases of construction the source of the wall adobe changed. Many of the soil samples are included in wall clusters and therefore reveal a potential source of material used for adobe, adjacent soils. However, not all the soil surrounding the pueblo grouped with wall clusters indicating a preference for certain soil types and that some soils were probably unsuitable for making adobe. Therefore, diversity in spectrally identified construction materials provides insights into source locations and possible construction preferences of the site inhabitants. © 2007 Wiley Periodicals, Inc. [source] Geoarchaeology of the Boca Negra Wash Area, Albuquerque Basin, New Mexico, USAGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2006Vance T. Holliday Dozens of Paleoindian sites, including the Boca Negra Wash (BNW) Folsom site (LA 124474), are scattered across a basalt plateau (the West Mesa) on the western side of the Albuquerque Basin, and adjacent uplands. The BNW site, like many others in the area, is located near a small (,60 × 90 m) playa basin that formed in a depression on the basalt surface and was subsequently covered by an eolian sand sheet (Unit 1) dated by OSL to ,23,000 yr B.P. Most of the basin fill is ,2 m of playa mud (Units 2 and 3) dating ,13,970 14C yr B.P. (17,160,16,140 cal yr B.P.) at the sand,mud interface to ,2810 14C yr B.P. (,2960,2860 cal yr B.P.) at the top. C/N ratios suggest that the BNW playa basin probably held water more often during the Folsom occupation; stable carbon isotope values indicate C3 vegetation was more common as well, but C4 grasses became dominant in the Holocene. Cores extracted from four playa basins nearby revealed a similar stratigraphy and geochronology, documenting presence of wetlands on playa floors during the Paleoindian occupation of the area. © 2006 Wiley Periodicals, Inc. [source] Geochemical comparisons of silicified rhyolites from two prehistoric quarries and 11 prehistoric projectile points, Socorro County, New Mexico, U.S.A.GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2004Robert D. Dello-Russo This paper documents the results of nondestructive X-ray fluorescence (XRF) geochemical analyses and comparisons of silicified rhyolites from the Black Canyon and Sedillo Hill prehistoric quarries near Socorro, New Mexico, and subsequent comparisons of the quarry rhyolites with 11 temporally diagnostic projectile points. At the current level of analysis, findings indicate that (1) the two quarries are chemically distinct and (2) the lithic materials of two projectile points match the silicified rhyolite from the Black Canyon quarry, suggesting quarry use during the Early Archaic period (4800,3200 B.C.) and the Late Archaic period (1800,800 B.C.). A close match between the Black Canyon rhyolite and one other point provides tentative support for use of the quarry during the Clovis Paleoindian period (9500,9000 B.C.). Additional geochemical analyses of the two quarries and other regional sources should be undertaken to verify these results and further expand our understanding of prehistoric mobility in the Southwest. © 2004 Wiley Periodicals, Inc. [source] Inverted clast stratigraphy in an eolian archaeological environmentGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2002Brenda J. Buck Understanding the geomorphic history of eolian basins is important in interpreting the archaeological record and human responses to past environments. One hundred forty soil profiles were excavated and described in southern New Mexico and West Texas. Seven major late Quaternary stratigraphic units were found: La Mesa, eolian Jornada (I, II), eolian Isaacks' Ranch, eolian Organ (I, II, and III), Historical Blowsand, and the playa deposits of Petts Tank and Lake Tank. Each unit represents a period of landscape instability, eolian erosion, and concurrent deposition, followed by landscape stability and soil formation. Eolian erosion can form local surficial lag deposits if materials larger than the competence of the wind are present. However, erosional processes alone cannot explain the presence of older clasts at the surface with intact, younger deposits underneath. We propose a combination of processes: deflation in eolian windows, followed by lateral movement of clasts over areas that have not been deflated. The effects of these processes on artifact stratigraphy and archaeological interpretations could be significant. © 2002 Wiley Periodicals, Inc. [source] Processing, modelling and predicting time-lapse effects of overpressured fluid-injection in a fractured reservoirGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2002Erika Angerer Summary Time-lapse seismology is important for monitoring subsurface pressure changes and fluid movements in producing hydrocarbon reservoirs. We analyse two 4-D, 3C onshore surveys from Vacuum Field, New Mexico, USA, where the reservoir of interest is a fractured dolomite. In Phase VI, a time-lapse survey was acquired before and after a pilot tertiary-recovery programme of overpressured CO2 injection, which altered the fluid composition and the pore-fluid pressure. Phase VII was a similar time-lapse survey in the same location but with a different lower-pressure injection regime. Applying a processing sequence to the Phase VI data preserving normal-incidence shear-wave anisotropy (time-delays and polarization) and maximizing repeatability, interval-time analysis of the reservoir interval shows a significant 10 per cent change in shear-wave velocity anisotropy and 3 per cent decrease in the P -wave interval velocities. A 1-D model incorporating both saturation and pressure changes is matched to the data. The saturation changes have little effect on the seismic velocities. There are two main causes of the time-lapse changes. Any change in pore-fluid pressures modifies crack aspect ratios. Additionally, when there are overpressures, as there are in Phase VI, there is a 90° change in maximum impedance directions, and the leading faster split shear wave, instead of being parallel to the crack face as it is for low pore-fluid pressures, becomes orthogonal to the crack face. The anisotropic poro-elasticity (APE) model of the evolution of microcracked rock, calculates the evolution of cracked rock to changing conditions. APE modelling shows that at high overburden pressures only nearly vertical cracks, to which normal incidence P waves are less sensitive than S waves, remain open as the pore-fluid pressure increases. APE modelling matches the observed time-lapse effects almost exactly demonstrating that shear-wave anisotropy is a highly sensitive diagnostic of pore-fluid pressure changes in fractured reservoirs. In this comparatively limited analysis, APE modelling of fluid-injection at known pressure correctly predicted the changes in seismic response, particularly the shear-wave splitting, induced by the high-pressure CO2 injection. In the Phase VII survey, APE modelling also successfully predicted the response to the lower-pressure injection using the same Phase VI model of the cracked reservoir. The underlying reason for this remarkable predictability of fluid-saturated reservoir rocks is the critical nature and high crack density of the fluid-saturated cracks and microcracks in the reservoir rock, which makes cracked reservoirs critical systems. [source] Historical shrub,grass transitions in the northern Chihuahuan Desert: modeling the effects of shifting rainfall seasonality and event size over a landscape gradientGLOBAL CHANGE BIOLOGY, Issue 10 2003Qiong Gao Abstract We use a spatially explicit landscape model to investigate the potential role of rainfall on shrub,grass transitions in the Jornada Basin of southern New Mexico during the past century. In long-term simulations (1915,1998) along a 2700 m transect running from a dry lake bed to the foothills of a small mountain, we test two hypotheses: (i) that wetter winters and drier summers may have facilitated shrub encroachment in grasslands, and (ii) that increases in large precipitation events may have increased soil water recharge at deeper layers, thus favoring shrub establishment and growth. Our model simulations generally support the hypothesis that wetter winters and drier summers may have played a key role, but we are unable to reproduce the major shifts from grass- to shrub-domination that occurred in this landscape during the early part of the 1900s; furthermore, the positive shrub response to wetter winters and drier summers was only realized subsequent to the drought of 1951,1956, which was a relatively short ,window of opportunity' for increased shrub establishment and growth. Our simulations also generally support the hypothesis that an increase in the number of large precipitation events may also have favored shrub establishment and growth, although these results are equivocal, depending upon what constitutes a ,large' event and the timing of such events. We found complex interactions among (i) the amount/seasonality of rainfall, (ii) its redistribution in the landscape via run-on and runoff, (iii) the depth of the soil water recharge, and (iv) subsequent water availability for the growth and reproduction of shrubs vs. herbaceous plants at various landscape positions. Our results suggest that only a mechanistic understanding of these interactions, plus the role of domestic cattle grazing, will enable us to elucidate fully the relative importance of biotic vs. abiotic factors in vegetation dynamics in this semiarid landscape. [source] Treatment of a Chromate-Contaminated Soil Site by in situ Gaseous ReductionGROUND WATER MONITORING & REMEDIATION, Issue 1 2007E.C Thornton A proof-of-concept field test for the treatment of hexavalent chromium in the vadose zone using in situ gaseous reduction was successfully completed by the U.S. Department of Energy and U.S. Department of Defense in a joint demonstration conducted at White Sands Missile Range, New Mexico. The test involved injecting hydrogen sulfide, diluted in air, into contaminated vadose zone sediment to reduce Cr(VI) to Cr(III). The gaseous mixture was injected directly into the contaminated sediment through a central injection well and vacuum extracted through the flow field with six boreholes at the site periphery over a 76-d period. Comparison of soil samples taken before and after the test indicated 70% of the total mass of hexavalent chromium originally present at the site was reduced and immobilized. The zone of highest contamination was nearly completely treated, with average Cr(VI) concentrations decreasing in this interval from an average of 8.1 mg/kg before treatment to 1.1 mg/kg after treatment. Treatment was best in higher permeability clean gypsum sands and less effective in zones containing greater amounts of silt and clay and a slightly higher iron content. All hexavalent chromium concentrations measured in the posttest samples, however, were well below the remedial goal and regulatory limit of 30 mg/kg. In addition, the field test demonstrated that vadose zone treatment of contamination can be safely conducted using diluted hydrogen sulfide gas mixtures. Ongoing development of the technology is being directed toward addressing the limitations of gaseous treatment arising from variations in sediment permeability and iron content and assessing the relationship between hydrogen sulfide consumption and reaction kinetics. [source] Changes in hydrology and erosion over a transition from grassland to shrublandHYDROLOGICAL PROCESSES, Issue 4 2010Laura Turnbull Abstract The degradation of grasslands is a common problem across semi-arid areas worldwide. Over the last 150 years, much of the south-western United States has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Plot-based experiments to determine how spatio-temporal characteristics of soil moisture, runoff and erosion change over a transition from grassland to shrubland were carried out at four sites over a transition from black grama (Bouteloua eriopoda) grassland to creosotebush (Larrea tridentata) shrubland at the Sevilleta NWR LTER site in New Mexico. Each site consisted of a 10 × 30 m bounded runoff plot and adjacent characterization plots with nested sampling points where soil moisture content was measured. Results show distinct spatio-temporal variations in soil moisture content, which are due to the net effect of processes operating at multiple spatial and temporal scales, such as plant uptake of water at local scales versus the redistribution of water during runoff events at the hillslope scale. There is an overall increase in runoff and erosion over the transition from grassland to shrubland, which is likely to be associated with an increase in connectivity of bare, runoff-generating areas, although these increases do not appear to follow a linear trajectory. Erosion rates increased over the transition from grassland to shrubland, likely related in part to changes in runoff characteristics and the increased capacity of the runoff to detach, entrain and transport sediment. Over all plots, fine material was preferentially eroded which has potential implications for nutrient cycling since nutrients tend to be associated with fine sediment. Copyright © 2009 John Wiley & Sons, Ltd. [source] One- and two-dimensional modelling of overland flow in semiarid shrubland, Jornada basin, New MexicoHYDROLOGICAL PROCESSES, Issue 5 2006David A. Howes Abstract Two distributed parameter models, a one-dimensional (1D) model and a two-dimensional (2D) model, are developed to simulate overland flow in two small semiarid shrubland watersheds in the Jornada basin, southern New Mexico. The models are event-based and represent each watershed by an array of 1-m2 cells, in which the cell size is approximately equal to the average area of the shrubs. Each model uses only six parameters, for which values are obtained from field surveys and rainfall simulation experiments. In the 1D model, flow volumes through a fixed network are computed by a simple finite-difference solution to the 1D kinematic wave equation. In the 2D model, flow directions and volumes are computed by a second-order predictor,corrector finite-difference solution to the 2D kinematic wave equation, in which flow routing is implicit and may vary in response to flow conditions. The models are compared in terms of the runoff hydrograph and the spatial distribution of runoff. The simulation results suggest that both the 1D and the 2D models have much to offer as tools for the large-scale study of overland flow. Because it is based on a fixed flow network, the 1D model is better suited to the study of runoff due to individual rainfall events, whereas the 2D model may, with further development, be used to study both runoff and erosion during multiple rainfall events in which the dynamic nature of the terrain becomes an important consideration. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effects of the El Niño,southern oscillation on temperature, precipitation, snow water equivalent and resulting streamflow in the Upper Rio Grande river basinHYDROLOGICAL PROCESSES, Issue 6 2004Songweon Lee Abstract Snowmelt runoff dominates streamflow in the Upper Rio Grande (URG) basin of New Mexico and Colorado. Annual variations in streamflow timing and volume at most stations in the region are strongly influenced by the El Niño,southern oscillation (ENSO) through its modulation of the seasonal cycles of temperature and precipitation, and hence on snow accumulation and melting. After removing long-term trends over the study period (water years 1952,99), the dependence of monthly temperature, precipitation, snow water equivalent (SWE) at snowcourse stations, and streamflow throughout the URG on ENSO was investigated using composite analyses of the detrended residuals and through dependence of the residuals on the Climate Prediction Center southern oscillation index during the preceding summer and fall. The climate of La Niña years was found to differ significantly from either El Niño or neutral years. Moreover, significant climatological ENSO-related effects are confined to certain months, predominantly at the beginning and end of the winter season. In particular, March of La Niña years is significantly warmer and drier than during either El Niño or neutral years, and November of El Niño years is significantly colder and wetter. Differences in temperature and precipitation lead to significant differences in SWE and streamflow in the URG between the three ENSO phases. Copyright © 2004 John Wiley & Sons, Ltd. [source] Disposition of rainwater under creosotebushHYDROLOGICAL PROCESSES, Issue 13 2003Athol D. Abrahams Abstract In desert shrubland ecosystems water and nutrients are concentrated beneath shrub canopies in ,resource islands'. Rain falling on to these islands reaches the ground as either stemflow or throughfall and then either infiltrates into the soil or runs off as overland flow. This study investigates the partitioning of rainwater between stemflow and throughfall in the first instance and between infiltration and runoff in the second. Two series of 40 rainfall simulation experiments were performed on 16 creosotebush shrubs in the Jornada Basin, New Mexico. The first series of experiments was designed to measure the surface runoff and was performed with each shrub in its growth position. The second series was designed to measure stemflow reaching the shrub base and was conducted with the shrub suspended above the ground. The experimental data show that once equilibrium is achieved, 16% of the rainfall intercepted by the canopy or 6·7% of the rain falling inside the shrub area (i.e. the area inside the shrub's circumscribing ellipse) is funnelled to the shrub base as stemflow. This redistribution of the rainfall by stemflow is a function of the ratio of canopy area (i.e. the area covered by the shrub canopy) to collar area (i.e. a circular area centred on the shrub base), with stemflow rate being positively correlated and throughfall rate being negatively correlated with this ratio. The surface runoff rate expressed as a proportion of the rate at which rainwater arrives at a point (i.e. stemflow rate plus throughfall rate) is the runoff coefficient. A multiple regression reveals that 75% of the variance in the runoff coefficient can be explained by three independent variables: the rainfall rate, the ratio of the canopy area to the collar area, and the presence or absence of subcanopy vegetation. Although the last variable is a dummy variable, it accounts for 66·4% of the variance in the runoff coefficient. This suggests that the density and extent of the subcanopy vegetation is the single most important control of the partitioning of rainwater between runoff and infiltration beneath creosotebush. Although these findings pertain to creosotebush, similar findings might be expected for other desert shrubs that generate significant stemflow and have subcanopy vegetation. Copyright © 2003 John Wiley & Sons, Ltd. [source] Shifting covariability of North American summer monsoon precipitation with antecedent winter precipitationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2006Gregory J. McCabe Abstract Previous research has suggested that a general inverse relation exists between winter precipitation in the southwestern United States (US) and summer monsoon precipitation. In addition, it has been suggested that this inverse relation between winter precipitation and the magnitude of the southwestern US monsoon breaks down under certain climatic conditions that override the regional winter/monsoon precipitation relations. Results from this new study indicate that the winter/monsoon precipitation relations do not break down, but rather shift location through time. The strength of winter/monsoon precipitation relations, as indexed by 20-year moving correlations between winter precipitation and monsoon precipitation, decreased in Arizona after about 1970, but increased in New Mexico. The changes in these correlations appear to be related to an eastward shift in the location of monsoon precipitation in the southwestern US. This eastward shift in monsoon precipitation and the changes in correlations with winter precipitation also appear to be related to an eastward shift in July/August atmospheric circulation over the southwestern US that resulted in increased monsoon precipitation in New Mexico. Results also indicate that decreases in sea-surface temperatures (SSTs) in the central North Pacific Ocean also may be associated with the changes in correlations between winter and monsoon precipitation. Copyright © 2006 Royal Meteorological Society. [source] Synoptic climatology of extreme fire-weather conditions across the southwest United StatesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2006Michael A. Crimmins Abstract Extreme fire-weather conditions are usually thought of as discrete events rather than part of a continuum of meteorological and climatological variability. This study uses a synoptic climatological approach (weather typing) to examine the seasonal climatology of extreme fire-weather conditions across the southwest United States (Arizona and New Mexico) during the period of 1988,2003. Three key circulation patterns representing broad southwesterly flow and large geopotential height gradients are associated with over 80% of the extreme fire-weather days identified in this study. Seasonal changes in relative humidity levels, strength of height gradient, and geopotential heights all modulate the relationship between these key circulation patterns and extreme fire-weather days. Examination of daily incident summaries for three recent wildfires (May 2000, June 2002 and June 2003) shows that wildfire activity can be strongly regulated by these critical fire-weather circulation patterns. Copyright © 2006 Royal Meteorological Society. [source] Farm size, irrigation practices, and on-farm irrigation efficiency,IRRIGATION AND DRAINAGE, Issue 1 2005R. K. Skaggs Abstract Relationships between farm size, irrigation practices, and on-farm irrigation efficiency in the Elephant Butte Irrigation District, New Mexico, USA are explored using 2001 water delivery data supplied by the irrigation district. The study area is experiencing rapid population growth, development, and competition for existing water supplies. It is conventionally assumed that in the future water will be transferred from agriculture to other uses. Analysis of pecan orchard water delivery data, fieldwork, and interviews with irrigators found extremely long irrigation durations, inefficient irrigation practices, inadequate on-farm infrastructure, and lack of interest in making improvements to the current irrigation system or methods on the smallest farms. These findings are attributed to the nature of residential/lifestyle or retirement agriculture. Irrigation practices on large, commercial orchards are notably different from the smallest farms: irrigation event durations are shorter, less water is applied, and the producers are commercially oriented. With respect to future increases in the efficiency of irrigation water usage, large, commercially oriented producers already have a high level of physical efficiency. Small producers appear to view irrigation as a consumptive, recreational, social, or lifestyle activity, rather than an income-generating pursuit, thus the cost of inducing changes in their practices may be extremely high. Copyright © 2005 John Wiley & Sons, Ltd. [source] Relationship Between Frailty and Cognitive Decline in Older Mexican AmericansJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 10 2008Rafael Samper-Ternent MD OBJECTIVES: To examine the association between frailty status and change in cognitive function over time in older Mexican Americans. DESIGN: Data used were from the Hispanic Established Population for the Epidemiological Study of the Elderly. SETTING: Five southwestern states: Texas, New Mexico, Colorado, Arizona, and California. PARTICIPANTS: One thousand three hundred seventy noninstitutionalized Mexican-American men and women aged 65 and older with a Mini-Mental State Examination (MMSE) score of 21 or higher at baseline (1995/96). MEASUREMENTS: Frailty, defined as three or more of the following components: unintentional weight loss of more than 10 pounds, weakness (lowest 20% in grip strength), self-reported exhaustion, slow walking speed (lowest 20% in 16-foot walk time in seconds), and low physical activity level (lowest 20% on Physical Activity Scale for the Elderly score). Information about sociodemographic factors, MMSE score, medical conditions (stroke, heart attack, diabetes mellitus, arthritis, cancer, and hypertension), depressive symptoms, and visual impairment was obtained. RESULTS: Of the 1,370 subjects, 684 (49.9%) were not frail, 626 (45.7%) were prefrail (1,2 components), and 60 (4.4%) were frail (,3 components) in 1995/96. Using general linear mixed models, it was found that frail subjects had greater cognitive decline over 10 years than not frail subjects (estimate=,0.67, standard error=0.13; P<.001). This association remained statistically significant after controlling for potential confounding factors. CONCLUSION: Frail status in older Mexican Americans with MMSE scores of 21 or higher at baseline is an independent predictor of MMSE score decline over a 10-year period. Future research is needed to establish pathophysiological components that can clarify the relationship between frailty and cognitive decline. [source] | ||||||||||||||||||||||||||||