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101.
Viney P. Aneja Jeffrey S. Brittig Deug-Soo Kim Adel Hanna 《Journal of the Air & Waste Management Association (1995)》2013,63(6):681-688
Abstract An analysis of ozone (O3) concentrations and several other air quality-related variables was performed to elucidate their relationship with visibility at five urban and semi-urban locations in the southeast United States during the summer seasons of 1980-1996. The role and impact of O3 on aerosols was investigated to ascertain a relationship with visibility. Regional trend analysis over the 1980s reveals an increase in maximum O3 concentration coupled with a decrease in visibility. However, a similar analysis for the 1990s shows a leveling-off of both O3 and visibility; in both cases, the results were not statistically significant at the 5% level. A case study of site-specific trends at Nashville, TN, followed similar trends. To better understand the relationships between O3 concentration and visibility, the analysis was varied from yearly through daily to hourly averaged values. This increased temporal resolution showed a statistically significant inverse relationship between visibility and O3. Site-specific hourly r2 values ranged from 0.02 to 0.43. Additionally, by performing back-trajectory analysis, it was found that the visibility degraded by air mass migration over polluted areas. 相似文献
102.
Hyoung-June Im Young-Jun Kwon Soo-Geun Kim Yong-Kyu Kim Young-Su Ju Hwa-Pyung Lee 《Safety Science》2009,47(8):1159-1162
This study is aimed at exploring the characteristics of fatal occupational injuries in Korea’s construction industry and comparing the causes in various occupations within that industry. There were 10,276 fatal occupational injury victims in Korea over 8 years (1997–2004). The mortality risk due to injuries in construction and non-construction industries was calculated, and their causes were compared. The number of victims of fatal occupational injuries in the construction industry was 4333 (42.2% of the total fatal occupational injuries), and the 1 year mortality risk was higher (23.7/100,000 persons) than in non-construction industries (10.4). Falling was the most frequent (52.7%) cause of fatal injuries. In addition, deaths due to structural collapse and electric shock were significantly higher than in other industries. When the distribution of the causal factors in various occupations within the construction industry was investigated, some factors appeared more frequently in certain occupations than in others. As the construction industry encompasses a large proportion of occupational injuries, a reduction in this field alone will substantially contribute to an overall reduction of occupational injuries in Korea. Further research for effective prevention is needed. 相似文献
103.
104.
Characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater effluent 总被引:2,自引:0,他引:2
Constructed wetland (CW) is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary effluent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery wastewater effluent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the CW were non-apatite phosphorus (59%) and residual phosphorus (32%) suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW system and design. 相似文献
105.
Multiple linear regression models of urban runoff pollutant load and event mean concentration considering rainfall variables 总被引:8,自引:0,他引:8
Rainfall is an important factor in estimating the event mean concentration (EMC) which is used to quantify the washed-off pollutant concentrations from non-point sources (NPSs). Pollutant loads could also be calculated using rainfall, catchment area and runoff coefficient. In this study, runoff quantity and quality data gathered from a 28-month monitoring conducted on the road and parking lot sites in Korea were evaluated using multiple linear regression (MLR) to develop equations for estimating pollutant loads and EMCs as a function of rainfall variables. The results revealed that total event rainfall and average rainfall intensity are possible predictors of pollutant loads. Overall, the models are indicators of the high uncertainties of NPSs; perhaps estimation of EMCs and loads could be accurately obtained by means of water quality sampling or a long term monitoring is needed to gather more data that can be used for the development of estimation models. 相似文献
106.
This article describes the integrated modeling approach for planning the size and the operation of constructed wetlands for
maximizing retention of nonpoint source pollutant loads and reservoir water-quality improvement at a catchment scale. The
experimental field-scale wetland systems (four sets, 0.88 ha each) have been in operation since 2002, where water depth was maintained
at 30–50 cm and hydraulic loading rate was at 6.3–18.8 cm/day. The wetland system was found to be adequate for treating polluted
stream water with stable removal e ciency even during the winter. The integrated modeling system (modified-BASINS) was applied to
the Seokmoon estuarine reservoir watershed and calibrated with monitoring data from constructed wetland, stream, and reservoir. The
calibrated integrated modeling system estimated that constructing wetlands on 0.5% (about 114 ha) of the watershed area at the mouth
of reservoir could reduce 11.61% and 13.49% of total external nitrogen and phosphorus loads, respectively. It also might improve the
nitrogen and phosphorus concentration of the reservoir by 9.69% and 16.48%, respectively. The study suggested that about 0.1%–1.0%
of the watershed area should be allocated for constructed wetland to meet specified water-quality standards for the estuarine reservoir
at the polder area where land use planning is relatively less complicated. 相似文献
107.
Influence of Indian mustard (Brassicajuncea) on rhizosphere soil solution chemistry in long-term contaminated soils: A rhizobox study 总被引:1,自引:0,他引:1
This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved
organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation
of Indian mustard in the rhizobox filled four di erent types of heavy metal contaminated soils (two alkaline soils and two acidic
soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic
soils and only a slight increase (< 0.1 pH units) in alkaline soils. Furthermore, the DOC concentration increased by 17–156 mg/L
in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion
chromatographic determination showed a marked increase in the total dissolved organic acids (OAs) in rhizosphere. While root exudates
were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst di erent soils, resulting in
significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased
in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb,
and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal
solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and
Zn from solid phase to liquid phase. 相似文献
108.
Kines P Andersen LP Spangenberg S Mikkelsen KL Dyreborg J Zohar D 《Journal of Safety Research》2010,41(5):399-406
Background
The construction industry is one of the most injury-prone industries, in which production is usually prioritized over safety in daily on-site communication. Workers have an informal and oral culture of risk, in which safety is rarely openly expressed. This paper tests the effect of increasing leader-based on-site verbal safety communication on the level of safety and safety climate at construction sites. Method: A pre-post intervention-control design with five construction work gangs is carried out. Foremen in two intervention groups are coached and given bi-weekly feedback about their daily verbal safety communications with their workers. Foremen-worker verbal safety exchanges (experience sampling method, n = 1,693 interviews), construction site safety level (correct vs. incorrect, n = 22,077 single observations), and safety climate (seven dimensions, n = 105 questionnaires) are measured over a period of up to 42 weeks. Results: Baseline measurements in the two intervention and three control groups reveal that foremen speak with their workers several times a day. Workers perceive safety as part of their verbal communication with their foremen in only 6-16% of exchanges, and the levels of safety at the sites range from 70-87% (correct observations). Measurements from baseline to follow-up in the two intervention groups reveal that safety communication between foremen and workers increases significantly in one of the groups (factor 7.1 increase), and a significant yet smaller increase is found when the two intervention groups are combined (factor 4.6). Significant increases in the level of safety are seen in both intervention groups (7% and 12% increases, respectively), particularly in regards to 'access ways' and 'railings and coverings' (39% and 84% increases, respectively). Increases in safety climate are seen in only one of the intervention groups with respect to their 'attention to safety.' No significant trend changes are seen in the three control groups on any of the three measures. Conclusions: Coaching construction site foremen to include safety in their daily verbal exchanges with workers has a significantly positive and lasting effect on the level of safety, which is a proximal estimate for work-related accidents. It is recommended that future studies include coaching and feedback at all organizational levels and for all involved parties in the construction process. Building client regulations could assign the task of coaching to the client appointed safety coordinators or a manager/supervisor, and studies should measure longitudinal effects of coaching by following foremen and their work gangs from site to site. 相似文献109.
With the increase in employment of Internet surveys, there is a need to address how this survey mode affects inferences. Internet and interview modes are compared in estimating the preservation value of Dokdo, South Korea. Estimates of willingness to pay in the Internet survey are smaller than those in the interview survey. This may be attributable to the interview respondents being conscious of the presence of the interviewers, given the social importance of Dokdo to Koreans. Internet surveys may be effective in reducing overestimation of the willingness to pay in situations where potential social desirability is present. 相似文献
110.
Design and operating parameters, and cause and effect relationships among feedstocks and products in the pyrolysis of waste polymers are needed if this method of processing is to be used for energy recovery from waste plastics. The purpose of this study was to quantify the effect of various operating factors for the pyrolysis of common polymeric wastes. Experiments were performed using a conventional retort tube as a batch reactor. The operating factors considered were temperature and reaction time at constant heating rate. High density polyethylene (PE) and polystyrene (PS), the most common plastic waste in Korea, were used singly and in mixture.The pyrolysis time for maximum oil production from a PE-PS mixture was shorter than in the case of PE alone, showing an enhancement effect from the PS. The maximum gas production time from PE-PS mixtures was shorter than for PE alone at 500° C; above 600° C, this does not occur. Small aromatic compounds (which can be valuable) are produced at maximum with an 1:1 mixture of PE and PS at 600° C, showing the possibility of process control for the maximum recovery of desirable pyrolysis products. The maximum yield of toluene, xylene, styrene, and 1-propenyl benzene were 8.6, 8.9, 51.0 and 7.4 wt.% of feed for pyrolysis PS at 700° C, respectively. For naphthalene, it was at 700° C with 1:1 PE:PS (by wt.). The maximum recovery was 1.3 wt.%. Diels-Alder theory can explain the formation of aromatic compounds in the pyrolysis products. The yield of these secondary pyrolysis products can be controlled by reaction time, pyrolysis temperature and mixing ratio of plastic wastes in the pyrolysis feed. 相似文献