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221.
Work autonomy is one important component of job design theory which in recent decades has been elaborated upon by a number of researchers who have argued that it may be disaggregated into separate work method, work schedule and work criterion autonomy facets. Breaugh (1985) developed the Work Autonomy Scales as measures of each of these. This article reports the results of two studies carried out in Egypt that explored the validity of Breaugh's scales in relation to job design theory. In Study 1, in which Breaugh's scales were administered to 534 employees in two large Egyptian organizations, the Work Autonomy Scales' three‐factor structure was verified using exploratory and confirmatory factor analyses. In Study 2, using a sample of 120 managers from four organizations, the associations between the three facets of work autonomy and other variables with which they would be expected to correlate, along with their relationships with a number of outcome variables, were explored. Statistically significant correlations were observed between certain of the work autonomy scales and task interdependence, Hackman and Oldham's autonomy scale and job complexity. In terms of outcomes, work schedule autonomy was associated with job commitment, while work criterion autonomy was associated with job satisfaction. The results are discussed in the light of previous findings and some suggestions for future research are offered. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
222.
The ability to reuse carbonatic lake-dredged materials (CLDM) for agricultural purposes is important because it reduces offshore disposal and provides an alternative to disposal of the materials in landfills that are already overtaxed. A four-year (2001 to 2005) study on land application of CLDM as an option for disposal was conducted on a beef cattle pasture in south central Florida. The objectives of this study were (i) to assess CLDM as a soil amendment to improve quality of sandy soils in most subtropical beef cattle pastures and (ii) to determine the effect of CLDM on productivity and nutritive values of bahiagrass (BG, Paspalum notatum Flügge) in subtropical beef cattle pasture. The five treatment combinations arranged in randomized complete block design were represented by plots with different ratios (R) of natural soil (NS) to CLDM: R1 (1000 g kg(-1):0 g kg(-1)); R2 (750 g kg(-1):250 g kg(-1)); R3 (500 g kg(-1):500 g kg(-1)); R4 (250 g kg(-1):750 g kg(-1)); and R5 (0 g kg(-1):1000 g kg(-1)). Addition of CLDM had significant (p < or = 0.001) effects on soil quality and favorable influence on forage establishment and nutritive values. Compared with the control plots (0 g kg(-1)), the soils in plots amended with CLDM exhibited (i) lower penetration resistance, (ii) an increase in soil pH and exchangeable cations (Ca and Mg), and (iii) decrease in the levels of soil trace metals (Mn, Cu, Fe, Zn, and Si). Results disclosed consistently and significantly (p < or = 0.001) higher BG biomass production (forage yield = -106.3x(2) + 1015.8x - 39.2; R(2) = 0.99**) and crude protein content (CP = 1.24x + 6.48; R(2) = 0.94**) from plots amended with CLDM than those of BG planted on plots with no CLDM treatment.  相似文献   
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Atmospheric mercury (Hg) species, including gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate-bound mercury (Hgp), were monitored near three sites, including a cement plant (monitored in 2007 and 2008), an urban site and a rural site (both monitored in 2005 and 2008). Although the cement plant was a significant source of Hg emissions (for 2008, GEM: 2.20 ± 1.39 ng m?3, RGM: 25.2 ± 52.8 pg m?3, Hgp 80.8 ± 283 pg m?3), average GEM levels and daytime average dry depositional RGM flux were highest at the rural site, when all three sites were monitored sequentially in 2008 (rural site, GEM: 2.37 ± 1.26 ng m?3, daytime RGM flux: 29 ± 40 ng m?2 day?1). Photochemical conversion of GEM was not the primary RGM source, as highest net RGM gains (75.9 pg m?3, 99.0 pg m?3, 149 m?3) occurred within 3.0–5.3 h, while the theoretical time required was 14–23 h. Instead, simultaneous peaks in RGM, Hgp, ozone (O3), nitrogen oxides, and sulfur dioxide in the late afternoon suggested short-range transport of RGM from the urban center to the rural site. The rural site was located more inland, where the average water vapor mixing ratio was lower compared to the other two sites (in 2008, rural: 5.6 ± 1.4 g kg?1, urban: 9.0 ± 1.1 g kg?1, cement plant: 8.3 ± 2.2 g kg?1). Together, these findings suggested short-range transport of O3 from an urban area contributed to higher RGM deposition at the rural site, while drier conditions helped sustain elevated RGM levels. Results suggested less urbanized environments may be equally or perhaps more impacted by industrial atmospheric Hg emissions, compared to the urban areas from where Hg emissions originated.  相似文献   
225.
In 2017, Consumers Energy completed a sediment response action in the Flint River to address manufactured gas plant‐related impacts in sediments and at the groundwater‐surface water interface. The project site is located in an urban, channelized, developed reach of the river. Multiple property owners and site constraints presented unique challenges for the remedial design, including the presence of Hamilton Dam at the downstream edge of the site which was considered a high‐hazard dam in “very poor condition.” An additional consideration was the City of Flint water crisis which was initially exposed in 2014. The sediment response action was not related to the water crisis because the site is located approximately two miles downstream of the City's water intake, but design, permitting, and construction began after 2014, so the timing added a heightened sense of awareness from the public stakeholders. The successful completion of the sediment response action was the result of deliberate planning, iterative engineering, and open communication with stakeholders that enabled a careful balancing of objectives with sometimes competing interests.  相似文献   
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With a particular focus on low income economies in SSA, this paper addresses the nature and determinants of linkages from the commodities sectors and challenges the received view that enclave development is an inherent characteristic of resource extraction, particularly in the hard and energy commodities sectors. It argues that there has been a steady increase in linkage development and that there are significant opportunities for deepening this process. The opportunities may be greater for backward than for forward linkages, particularly in the minerals and energy sectors. In making this case, this Discussion Paper draws on the experience of high income countries which have resource intensive economic structures, the geographical specificity of many resources and the growing interest of large resource extracting firms in outsourcing the production of inputs which are outside of their core competences and in supporting local production of some inputs, it sets out a general model of linkage development which distinguishes between win–win and win–lose outcomes.  相似文献   
228.
Allums, Stephanie E., Stephen P. Opsahl, Stephen W. Golladay, David W. Hicks, and L. Mike Conner, 2012. Nitrate Concentrations in Springs Flowing Into the Lower Flint River Basin, Georgia U.S.A. Journal of the American Water Resources Association (JAWRA) 48(3): 423-438. DOI: 10.1111/j.1752-1688.2011.00624.x Abstract: Analysis of long-term data from (2001-2009) in four springs that discharge from the Upper Floridan aquifer into the Flint River (southwestern Georgia, United States) indicate aquifer and surface-water susceptibility to nutrient loading. Nitrate-N concentrations ranged from 1.74 to 3.30 mg/l, and exceeded historical levels reported for the Upper Floridan aquifer (0.26-1.52 mg/l). Statistical analyses suggest increasing nitrate-N concentration in groundwater discharging at the springs (n = 146 over eight years) and that nitrate-N concentration is influenced by a dynamic interaction between depth to groundwater (an indicator of regional hydrologic conditions) and land use. A one-time synoptic survey of 10 springs (6 springs in addition to the 4 previously mentioned) using stable isotopes generated δ15N-NO3 values (4.8-8.4‰ for rural springs and 7.7-13.4‰ for developed/urban springs) suggesting mixed sources (i.e., fertilizer, animal waste, and soil organic nitrogen) of nitrate-N to rural springs and predominantly animal/human waste to urban springs. These analyses indicate a direct relation between nitrate-N loading since the 1940s and intensification of agricultural and urban land use. This study demonstrates the importance of evaluating long-term impacts of land use on water quality in groundwater springs and in determining how rapidly these changes occur.  相似文献   
229.
Due to relatively high chelant dosages and potential environmental risks it is necessary to explore different approaches in the remediation of metal-contaminated soils. The present study focussed on the removal of metals (As, Cd, Cu, Pb and Zn) from a multiple metal-contaminated soil by growing Brassica carinata plants in succession to spontaneous metallicolous populations of Pinus pinaster, Plantago lanceolata and Silene paradoxa. The results showed that the growth of the metallicolous populations increased the extractable metal levels in the soil, which resulted in a higher accumulation of metals in the above-ground parts of B. carinata. Root exudates of the three metallicolous species were analysed to elucidate their possible role in the enhanced metal availability. The presence of metals stimulated the exudation of organic and phenolic acids as well as flavonoids. It was suggested that root exudates played an important role in solubilising metals in soil and in favouring their uptake by roots.  相似文献   
230.
Recent enhanced urbanization and industrialization in China have greatly influenced soil Cu content. To better understand the magnitude of Cu contamination in soil, it is essential to understand its spatial distribution and estimate its values at unsampled points. However, Kriging often can not achieve satisfactory estimates when soil Cu data have weak spatial dependence. The proposed classification and regression tree method (CART) simulated Cu content using environmental variables, and it had no special data requirements. The Cu concentration classes estimated by CART had accuracy in attribution to the right classes of 80.5%, this is 29.3% better than ordinary Kriging method. Moreover, CART provides some insight into the sources of current soil Cu contents. In our study, low soil Cu accumulation was driven by terrain characteristic, agriculture land uses, and soil properties; while high Cu concentration resulted from industrial and agricultural land uses.  相似文献   
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