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81.
Fast economic and social changes in recent years in China have brought massive expansion, redevelopment, and restructuring of cities. These changes offer cities the opportunity to improve environmental quality through urban green spaces (UGSs) and to address the challenges of meeting community aspirations. This study explored peoples’ minds concerning UGSs in Guangzhou city in south China in relation to the following: (1) knowledge and perception of 25 ecosystem services and 8 negative impacts; (2) attitude toward site condition and management; (3) expectation of landscape design; and (4) preference ranking of venues. A questionnaire was designed to solicit opinions from 340 respondents randomly chosen from residents living in the study area. The results indicated widespread recognition of ecosystem services and strong support of UGS programs. Negative responses were weakly expressed. Amelioration of urban microclimate and environmental quality were emphasized. Environmental functions stressed in publicity programs, together with aggravating environmental problems in the city, tended to focus respondents’ attention on UGS benefits. Wildlife habitat, species conservation and other natural ecosystem services drew limited concerns. Awareness of economic benefits was very low. Visual-landscape contributions with strong preference for naturalistic design and recreational benefits were highlighted. Compared with other countries, Guangzhou residents were characterized by visual–scenic–recreation orientation and pragmatic–utilitarian perception of UGSs, reflecting underlying differences in the understanding of inherent ecosystem services of green spaces. Relevant UGS policies and practices could adopt the approaches of market survey, citizen participation, and precision planning in order to meet increasingly mature and refined demands. Citizens’ understanding of high-order ecosystem services could be enhanced to encourage appreciation of nature and their associated benefits.  相似文献   
82.
A number of models have been developed to explain nurses' turnover behavior. The common theme that emerges from these models is that turnover behavior is a multistage process that includes attitudinal, decisional, and behavioral components. The purpose of this study was to assess both the direct and indirect impact of certain pay policies upon the turnover intentions of paediatric nurses. The two major questions addressed were: What was the relative impact of job satisfaction, pay satisfaction, and organizational commitment upon the turnover intentions of paediatric nurses eligible for these pay policies? What model accurately portrays the relationship among these three independent variables and turnover intentions? Exploration of the causal pathways among these variables and demographic factors revealed complex models of association. The results suggest that job satisfaction has only an indirect influence on the intention to quit, whereas organizational commitment has the strongest and most direct impact. A further finding that pay satisfaction had both direct and indirect effects on turnover intent was consistent with administrators' assumptions underlying the pay policies. Control variables such as having a degree, having children, and working 12-hour shifts were found to have both direct and indirect influences upon pay satisfaction and turnover intent. © 1998 John Wiley & Sons, Ltd.  相似文献   
83.
Gas emissions were determined for dairy cows fed three diets formulated to represent feed ingredients typical of the Midwest, South, or West regions of the United States. Dairy cows were housed and monitored in 12 environmentally controlled rooms (4 cows diet). Two experiments were performed, representing two lactation stages (initial days in milk were 115 ± 39 d in Stage 1 and 216 ± 48 d in Stage 2). The results demonstrated that the combination of different dietary ingredients resulted in different gas emissions while maintaining similar dry matter intake (DMI) and milk yield (MY). Diet effect on ammonia (NH) emissions was more prominent in Stage 1. During Stage 1, cows fed the Midwest diet had the highest daily NH emission, corresponding to the highest crude protein (CP) concentration among the three regions. The differences in NH emissions (39.0%) were much larger than the percent difference in CP concentrations between diets (6.8%). Differences in N intake, N excretion, or milk urea N alone may not serve as a strong indicator of the potential to reduce NH emissions. Lower emissions of methane (CH) per unit DMI or per unit MY were observed for cows offered the South diet during Stage 1 as compared with that from cows offered the Midwest or West diets. No diet effect was observed for hydrogen sulfide (HS) emission per unit S intake, nor for nitrous oxide (NO) emission. The measured NH and CH emissions were comparable, but the NO emissions were much higher than those reported for tie-stall dairy barns in the literature.  相似文献   
84.
The disposal of hazardous crude oil tank bottom sludge (COTBS) represents a significant waste management burden for South Mediterranean countries. Currently, the application of biological systems (bioremediation) for the treatment of COTBS is not widely practiced in these countries. Therefore, this study aims to develop the potential for bioremediation in this region through assessment of the abilities of indigenous hydrocarbonoclastic microorganisms from Libyan Hamada COTBS for the biotreatment of Libyan COTBS-contaminated environments. Bacteria were isolated from COTBS, COTBS-contaminated soil, treated COTBS-contaminated soil, and uncontaminated soil using Bushnell Hass medium amended with Hamada crude oil (1 %) as the main carbon source. Overall, 49 bacterial phenotypes were detected, and their individual abilities to degrade Hamada crude and selected COBTS fractions (naphthalene, phenanthrene, eicosane, octadecane and hexane) were evaluated using MT2 Biolog plates. Analyses using average well colour development showed that ~90 % of bacterial isolates were capable of utilizing representative aromatic fractions compared to 51 % utilization of representative aliphatics. Interestingly, more hydrocarbonoclastic isolates were obtained from treated contaminated soils (42.9 %) than from COTBS (26.5 %) or COTBS-contaminated (30.6 %) and control (0 %) soils. Hierarchical cluster analysis (HCA) separated the isolates into two clusters with microorganisms in cluster 2 being 1.7- to 5-fold better at hydrocarbon degradation than those in cluster 1. Cluster 2 isolates belonged to the putative hydrocarbon-degrading genera; Pseudomonas, Bacillus, Arthrobacter and Brevundimonas with 57 % of these isolates being obtained from treated COTBS-contaminated soil. Overall, this study demonstrates that the potential for PAH degradation exists for the bioremediation of Hamada COTBS-contaminated environments in Libya. This represents the first report on the isolation of hydrocarbonoclastic bacteria from Libyan COTBS and COTBS-contaminated soil.  相似文献   
85.
A Method for Setting the Size of Plant Conservation Target Areas   总被引:3,自引:0,他引:3  
Abstract: Realistic time frames in which management decisions are made often preclude the completion of the detailed analyses necessary for conservation planning. Under these circumstances, efficient alternatives may assist in approximating the results of more thorough studies that require extensive resources and time. We outline a set of concepts and formulas that may be used in lieu of detailed population viability analyses and habitat modeling exercises to estimate the protected areas required to provide desirable conservation outcomes for a suite of threatened plant species. We used expert judgment of parameters and assessment of a population size that results in a specified quasiextinction risk based on simple dynamic models. The area required to support a population of this size is adjusted to take into account deterministic and stochastic human influences, including small-scale disturbance, deterministic trends such as habitat loss, and changes in population density through processes such as predation and competition. We set targets for different disturbance regimes and geographic regions. We applied our methods to Banksia cuneata, Boronia keysii, and Parsonsia dorrigoensis, resulting in target areas for conservation of 1102, 733, and 1084 ha, respectively. These results provide guidance on target areas and priorities for conservation strategies.  相似文献   
86.
Pentachlorophenol (PCP) has been used as a herbicide, biocide and preservative worldwide since the 1930s and as a result, extensive and prolonged contamination exists. The environmental impact increases when its many degradation products are taken into consideration. A number of chloroanisols and their related chlorophenols have been found in cork slabs collected from Portuguese oak tree forests before stopper manufacturing, and contamination by PCP and polychlorinated anisole (PCA) has been detected in Canadian forests. It is suggested that the use of polychlorinated phenols, in particular PCP, is thought to be a cause of the cork taint problem in wine, a major socio-economic impact not only for industry but on sensitive and highly biodiverse ecosystems. It also highlights particular issues relating to the regional regulation of potentially toxic chemicals and global economics world wide. To fully understand the impact of contamination sources, the mechanisms responsible for the fate and transport of PCP and its degradation products and assessment of their environmental behaviour is required. This review looks at the current state of knowledge of soil sorption, fate and bioavailability and identifies the challenges of degradation product identification and the contradictory evidence from field and laboratory observations. The need for a systematic evaluation of PCP contamination in relation to cork forest ecosystems and transfer of PCP between trophic levels is emphasised by discrepancies in bioaccumulation and toxicity. This is essential to enable long term management of not only transboundary contaminants, but also the sustainable management of socially and economically important forest ecosystems.  相似文献   
87.
Abstract

For at least 30 years, ozone (O3) levels on weekends in parts of California’s South Coast (Los Angeles) Air Basin (SoCAB) have been as high as or higher than on weekdays, even though ambient levels of O3 precursors are lower on weekends than on weekdays. A field study was conducted in the Los Angeles area during fall 2000 to test whether proposed relationships between emission sources and ambient nonmethane hydrocarbon (NMHC) and oxides of nitrogen (NOx) levels can account for observed diurnal and day-of-week variations in the concentration and proportions of precursor pollutants that may affect the efficiency and rate of O3 formation. The contributions to ambient NMHC by motor vehicle exhaust and evaporative emissions, estimated using chemical mass balance (CMB) receptor modeling, ranged from 65 to 85% with minimal day-of-week variation. Ratios of ambient NOx associated with black carbon (BC) to NOx associated with carbon monoxide (CO) were approximately 1.25 ± 0.22 during weekdays and 0.76 ± 0.07 and 0.52 ± 0.07 on Saturday and Sunday, respectively. These results demonstrate that lower NOx emissions from diesel exhaust can be a major factor causing lower NOx mixing ratios and higher NMHC/NOx ratios on weekends. Nonmobile sources showed no significant day-of-week variations in their contributions to NMHC. Greater amounts of gasoline emissions are carried over on Friday and Saturday evenings but are, at most, a minor factor contributing to higher NMHC/NOx ratios on weekend mornings.  相似文献   
88.
2,2,4-trimethyl, 1,3-pentanediol monoisobutyrate (TPM) is a widely used solvent found in water-based coatings. Ambient measurements of TPM are reported here for the first time. Although this compound has been previously measured in indoor air, this study illustrates successful detection and quantification of TPM in ambient air at three locations in Southern California: Pico Rivera, Azusa, and Riverside. TPM was detected in every sample collected, with concentrations ranging from 0.7 to 49.5 parts per trillion (ppt). Collections took place during summer 2009, fall 2009, winter 2009/2010, and spring 2010, for 5–7 days during each season. The highest mean concentrations were observed during the summer months for each city, when coating activities are typically at their highest.

Implications 2,2,4-Trimethyl, 1,3-pentanediol monoisobutyrate (TPM) is a widely used solvent found in water-based coatings. Ambient measurements of TPM are reported here for the first time. The highest mean concentrations were observed during the summer months for each city, when coating activities are typically at their highest. Unreacted TPM constitutes approximately 0.01% of the total nonmethane hydrocarbon (NMHC) concentrations in the Los Angeles air basin and given its slow reactivity rate in forming ozone, this would be an approximate upper limit for the fraction of ozone that it is responsible for forming.  相似文献   
89.
The human diet is recognised as one possible major exposure route to the overall perfluorinated alkylated substances (PFAS) burden of the human population, resulting directly from contamination of dietary food items, as well as migration of PFAS from food packaging or cookware. Most European countries carry out national monitoring programs (food basket studies) to monitor contamination with pollutants. Usually, for PFASs, non-coordinated approaches are used in Europe, since food basket studies are mainly carried out by national authorities following national requirements and questions, making comparisons between different countries difficult. A harmonised sampling campaign collecting similar food items in a uniform procedure enabling direct comparison between different regions in Europe was designed. We selected four countries (Belgium, Czech Republic, Italy and Norway), representing the four regions of Europe: West, East, South and North. In spring 2010 and 2011, 20 different types of vegetables were sampled in Belgium, Czech Republic, Italy and Norway. Perfluorinated carboxylic acids (PFCAs) were the main group of detected PFASs, with perfluorinated octanoic acid (PFOA) as the most abundant PFCA (with exception of samples from Czech Republic), followed by perfluorinated hexanoic acid and perfluorinated nonanoic acid. Dietary intake estimates for PFOA show only low human exposure due to vegetable consumption for adults and children, mostly governed by high intake of potatoes.  相似文献   
90.
A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a chemical, chemical associations with discrete types of equipment, chemical profiling, degradation models and contaminant transport models. The success of these techniques in environmental litigation and their applicability to a particular fact situation is rarely discussed in the literature. When these techniques are introduced as scientific evidence, their governing assumptions and the adequacy of the underlying data are rigorously scrutinized and often, successfully challenged. The purpose of this paper is to review selected forensic techniques and discuss their merits so that the user can select the technique or combination of techniques most appropriate for the factual elements of the case.  相似文献   
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