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581.
Gary C. White 《Environmental and Ecological Statistics》2008,15(1):89-99
Program MARK provides > 65 data types in a common configuration for the estimation of population parameters from mark-encounter
data. Encounter information from live captures, live resightings, and dead recoveries can be incorporated to estimate demographic
parameters. Available estimates include survival (S or ϕ), rate of population change (λ), transition rates between strata (Ψ), emigration and immigration rates, and population
size (N). Although N is the parameter most often desired by biologists, N is one of the most difficult parameters to estimate precisely without bias for a geographically and demographically closed
population. The set of closed population estimation models available in Program MARK incorporate time (t) and behavioral (b) variation, and individual heterogeneity (h) in the estimation of capture and recapture probabilities in a likelihood framework. The full range of models from M
0 (null model with all capture and recapture probabilities equal) to M
tbh
are possible, including the ability to include temporal, group, and individual covariates to model capture and recapture
probabilities. Both the full likelihood formulation of Otis et al. (1978) and the conditional model formulation of Huggins
(1989, 1991) and Alho (1990) are provided in Program MARK, and all of these models are incorporated into the robust design
(Kendall et al. 1995, 1997; Kendall and Nichols 1995) and robust-design multistrata (Hestbeck et al. 1991, Brownie et al.
1993) data types. Model selection is performed with AICc (Burnham and Anderson 2002) and model averaging (Burnham and Anderson
2002) is available in Program MARK to provide estimates of N with standard error that reflect model selection uncertainty. 相似文献
582.
The effects of learning versus outcome distal goals in conjunction with proximal goals were investigated in a laboratory setting using a class‐scheduling task. The participants (n = 96) needed to acquire knowledge in order to perform the task correctly. A ‘do your best’ outcome goal led to higher performance than the assignment of a specific, difficult outcome goal. However, the assignment of a specific, difficult learning goal led to higher performance than urging people to ‘do their best.’ Goal commitment was higher in the learning goal than in the outcome goal condition. The correlation between task‐relevant strategies discovered and performance was positive and significant. The number of task‐relevant strategies implemented by participants assigned a distal learning goal in conjunction with proximal goals was higher than in any other goal condition. Setting a distal outcome or learning goal that included proximal outcome goals, however, did not lead to higher performance than the setting of a distal outcome or learning goal alone. Self‐efficacy correlated significantly with performance, and this effect was mediated through strategy development. Furthermore, the discovery of task‐relevant strategies affected self‐efficacy through an increase in performance. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
583.
584.
Bhanukiran SUNKARA Yang SU Jingjing ZHAN Jibao HE Gary L. MCPHERSON Vijay T. JOHN 《Frontiers of Environmental Science & Engineering》2015,9(5):939
Iron-carbon (Fe-C) composite microspheres prepared through a facile aerosol-based process are effective remediation agents for the simultaneous adsorption and reduction of chlorinated hydrocarbons. Complete dechlorination was achieved for the class of chlorinated ethenes that include tetrachloroethylene (PCE), trichloroethylene (TCE), cis- and trans-1,2-dicloroethylene (c-DCE, t-DCE), 1,1-dichloroethylene (1,1-DCE) and, vinyl chloride (VC). The Fe-C particles potentially provides multi-functionality with requisite characteristics of adsorption, reaction, and transport for the effective in situ remediation of chlorinated hydrocarbons. The carbon support immobilizes the ferromagnetic iron nanoparticles onto its surface, thereby inhibiting aggregation. The adsorptive nature of the carbon support prevents the release of toxic intermediates such as the dichloroethylenes and vinyl chloride. The adsorption of chlorinated ethenes on the Fe-C composites is higher (>80%) than that of humic acid (<35%) and comparable to adsorption on commercial activated carbons (>90%). The aerosol-based process is an efficient method to prepare adsorptive-reactive composite particles in the optimal size range for transport through the porous media and as effective targeted delivery agents for the in situ remediation of soil and groundwater contaminants. 相似文献
585.
Natural attenuation of chlorinated ethene compounds: model development and field-scale application at the Dover site 总被引:1,自引:0,他引:1
T. Prabhakar Clement Christian D. Johnson Yunwei Sun Gary M. Klecka Craig Bartlett 《Journal of contaminant hydrology》2000,42(2-4)
A multi-dimensional and multi-species reactive transport model was developed to aid in the analysis of natural attenuation design at chlorinated solvent sites. The model can simulate several simultaneously occurring attenuation processes including aerobic and anaerobic biological degradation processes. The developed model was applied to analyze field-scale transport and biodegradation processes occurring at the Area-6 site in Dover Air Force Base, Delaware. The model was calibrated to field data collected at this site. The calibrated model reproduced the general groundwater flow patterns, and also, it successfully recreated the observed distribution of tetrachloroethene (PCE), trichloroethene (TCE), dichloroethylene (DCE), vinyl chloride (VC) and chloride plumes. Field-scale decay rates of these contaminant plumes were also estimated. The decay rates are within the range of values that were previously estimated based on lab-scale microcosm and field-scale transect analyses. Model simulation results indicated that the anaerobic degradation rate of TCE, source loading rate, and groundwater transport rate are the important model parameters. Sensitivity analysis of the model indicated that the shape and extent of the predicted TCE plume is most sensitive to transmissivity values. The total mass of the predicted TCE plume is most sensitive to TCE anaerobic degradation rates. The numerical model developed in this study is a useful engineering tool for integrating field-scale natural attenuation data within a rational modeling framework. The model results can be used for quantifying the relative importance of various simultaneously occurring natural attenuation processes. 相似文献
586.
587.
In situ stabilization of soil lead using phosphorus and manganese oxide: influence of plant growth 总被引:2,自引:0,他引:2
In situ stabilization of Pb contaminated soils can be accomplished by adding P and Mn(IV) oxide. However, the long-term efficacy of in situ stabilization under continual P removal through plant growth is unknown. Moreover, the effects these treatments have on phytoavailability of other metals (Cd and Zn) commonly associated with Pb in soil are not well understood. Greenhouse experiments using sudax [Sorghum vulgare (L.) Moench] and Swiss chard [Beta vulgaris (L.) Koch] were carried out to evaluate the effects of plant growth on soil Pb bioavailability to humans after addition of P and other amendments, and the effects of these treatments on Pb, Cd, and Zn phytoavailability in three metal-contaminated soils. Eight treatments were used: zero P; 2500 mg of P as triple superphosphate (TSP); 5000 mg of P as TSP or phosphate rock (PR); 5000 mg of Mn oxide/kg; and combinations of Mn oxide and P as TSP or PR. The addition of P and/or Mn oxide significantly reduced bioavailable Pb, as measured by the physiologically based extraction test (PBET), in soils compared with the control even after extensive cropping. The PBET data also suggested that removal of P from soluble P sources by plants could negate the beneficial effects of P on bioavailable Pb, unless sufficient soluble P was added or soluble P was combined with Mn oxide. In general, Ph, Cd, and Zn concentrations in shoot tissues of sudax and Swiss chard were reduced significantly by TSP and did not change with the addition of PR. The combination of PR and Mn oxide significantly reduced Pb concentrations in plants compared with the control. 相似文献
588.
Interest in plant nutrient issues for sustainable land application of residuals is increasingly driven by environmental concerns. The indicators of concern are P and N in surface waters, nitrate leaching, and emissions of ammonia and greenhouse gases. Federal regulations require residual application rates to be on a N basis at most, and on a P basis when risk of P loss in surface runoff is high. Modeling of mineralization offers the potential for more accurate determinations of potentially available nitrogen (PAN) and quick tests could allow the determination of PAN on residuals immediately before land application. Methods for reducing ammonia emissions from livestock operations and new techniques for quantifying emissions under field conditions are being developed. Calibration and validation of P loss assessment tools is an ongoing concern and the interpretation of edge of field P losses warrants further attention. The solubility of P in residuals and soils can be influenced by various amendments or treatment processes. High available P grains or phytase enzyme supplementation can reduce total and soluble P in animal manures by reducing the need for diet supplementation with inorganic P. The use of synchrotron-based X-ray absorption spectroscopy has identified chemical forms of inorganic P. Considerable progress has been made addressing plant nutrient issues for sustainable land application and interest in this topic will remain strong into the foreseeable future. 相似文献
589.
Using Wildlife as Receptor Species: A Landscape Approach to Ecological Risk Assessment 总被引:4,自引:0,他引:4
Gaines KF Porter DE Dyer SA Wein GR Pinder JE Brisbin IL 《Environmental management》2004,34(4):528-545
To assist risk assessors at the Department of Energy’s Savannah River Site (SRS), a Geographic Information System (GIS) application was developed to provide relevant information about specific receptor species of resident wildlife that can be used for ecological risk assessment. Information was obtained from an extensive literature review of publications and reports on vertebrate- and contaminant-related research since 1954 and linked to a GIS. Although this GIS is a useful tool for risk assessors because the data quality is high, it does not describe the species’ site-wide spatial distribution or life history, which may be crucial when developing a risk assessment. Specific receptor species on the SRS were modeled to provide an estimate of an overall distribution (probability of being in an area). Each model is a stand-alone tool consisting of algorithms independent of the GIS data layers to which it is applied and therefore is dynamic and will respond to changes such as habitat disturbances and natural succession. This paper describes this modeling process and demonstrates how these resource selection models can then be used to produce spatially explicit exposure estimates. This approach is a template for other large federal facilities to establish a framework for site-specific risk assessments that use wildlife species as endpoints.Current address: Biology Department, University of South Dakota, Vermillion, SD 57069 相似文献
590.
Hettiarachchi GM Pierzynski GM Oehme FW Sonmez O Ryan JA 《Journal of environmental quality》2003,32(4):1335-1345
This study was conducted to determine the extent of Pb absorption into young rats (Rattus norvegicus var. Sprague-Dawley) fed untreated Pb-contaminated soil or Pb-contaminated soil treated with two different sources of P and P + Mn oxide. Data were compared from an in vitro, physiologically based extraction test (PBET) with the animal data to support the validity of the in vitro test to assess bioavailable Pb from a treated Pb-contaminated soil. Soil with a total Pb concentration of 2290 mg kg(-1) was used. Rats were fed 19 different test diets for 21 consecutive days. The test diets represented 95 g AIN93G rat meal kg(-1) diet with varying proportions of silica sand or soil to provide low, medium, or high doses of Pb from either Pb acetate, treated, or untreated soil. Blood, liver, kidney, and bone Pb concentrations were examined. For all four tissues, Pb concentrations for the Pb acetate groups were significantly higher than concentrations for all the soil groups. In general, either triple superphosphate (TSP) or phosphate rock (PR) treatments resulted in significant reductions in tissue Pb concentrations compared with untreated soil. Blood and kidney Pb concentrations for the PR + Mn oxide group were significantly lower than those of the PR group at the low and high doses. Relative bioavailability of Pb, as measured in all tissues, was significantly reduced when comparing untreated with amended soil. Correlation between the in vitro and in vivo tests, based on bone and liver tissue, showed that the in vitro test is successful at predicting Pb bioavailability. 相似文献