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971.
Chulsang Yoo Ungtae Kim Kyoungjun Kim Keewook Kim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(2):143-157
In this study an equation for estimating the error involved in the areal average rain rate considering the inter-station correlation
was derived and applied for two cases: the first compared two storm events with different inter-station correlations, and
the second evaluated the seasonal variation of estimation error of monthly rainfall. Similar cases, but without considering
the rainfall seasonality, were also investigated for the comparison. This study was applied to the Geum River Basin with 28
rain gauge measurements, each having more than 30 years of rainfall data. A summary of the application results follows: (1)
When considering the inter-station correlation, the estimation error involved in the areal average rain rate became significantly
decreased proportional to the inter-station correlation. (2) The estimation error of monthly areal average rainfall showed
strong seasonality with high ones during the wet season and lower ones during the dry season. (3) The estimation error was
well proportional to the areal average rain rate as well as to its standard deviation. The ratio of estimation error to the
areal average rain rate itself was estimated to be about 0.1 for the case of assuming no inter-station correlations, but decreased
to 0.06 for the case of considering the inter-station correlations between measurements. (4) The relation between the standard
deviation of areal average rain rate and the estimation error became much stronger than that between the areal average rain
rate itself and the estimation error. The ratio of estimation error to the standard deviations of rain rate amount was estimated
to be about 0.2 for the case of assuming no inter-station correlations, but decreased to 0.1 for the case of considering the
inter-station correlations. This relation was found to be valid for any case of accumulation time such as in daily, monthly,
or annual rainfall data. 相似文献
972.
We have compared near-fault ground motions from TeraShake simulations of Mw7.7 earthquake scenarios on the southern San Andreas Fault with precariously balanced rock locations. The TeraShake scenarios
with different directions of rupture generate radically different ground motions to the northwest of the Los Angeles Basin,
primarily because of directivity effects, and thus provide constraints on the ground motion and rupture direction for the
latest (1690) large event on that section of the San Andreas Fault. Due to the large directional near-field ground motions
predicted by the simulations, we expect the precariously balanced rocks to be located primarily in the backward rupture direction
or near the epicenter. Preliminary results favor persistent nucleation at or slightly northwest of the San Gorgonia Pass fault
zone for large earthquakes on the southern San Andreas Fault. 相似文献
973.
Influence of climate variation on seasonal precipitation in the Colorado River Basin 总被引:1,自引:1,他引:0
Tae-Woong Kim Chulsang Yoo Jae-Hyun Ahn 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(3):411-420
This study analyzed the influence of large-scale climate pattern on precipitation in the Colorado River Basin. Large-scale
climatic oscillations, like ENSO, PDO, NAO, and the global warming trend are associated with regional hydrologic variation.
Ten types of climate indices were gathered and analyzed to investigate their influence on seasonal precipitation variation
in the basin based on a linear correlation analysis and an influence index analysis. The influence index was developed in
this study to measure the effect of climate variation on the seasonal precipitation in the basin. The statistical evidence
achieved in this study confirms that the Colorado River Basin is subjected to the phase of climate variation. The strength
of the seasonal response of precipitation to the climate variation varies in different localities in the basin. The methods
of analysis used in this study were proposed in the hope that progress in understanding and modeling dynamic climatic systems
can result in developing a valuable long-term forecasting model for water resources management. 相似文献
974.
Integrated watershed management for mitigating streamflow depletion in an urbanized watershed in Korea 总被引:3,自引:0,他引:3
A systematic, seven-step approach to integrated watershed planning and management is applied to an urbanized watershed, the Anyangcheon (AY) watershed in Korea which consists of (1) understanding watershed components and processes, (2) identifying and ranking problems to be solved, (3) setting clear and specific goals, (4) developing a list of management options, (5) eliminating infeasible options (6) testing the effectiveness of remaining feasible options, and (7) developing the final options. Watershed characteristics, water quantity and quality simulations with SWAT and PLOAD models, and the developed problem indices of PFD (Potential Flood Damage), PSD (Potential Streamflow Depletion), and PWQD (Potential Water Quality Deterioration) identify that streamflow depletion is more serious than flood risk and water pollution in the study watershed (Steps 1 and 2). Instreamflow requirements, which are the maximum value of the average low flow and the fish flow, are estimated using regional regression and the software PHABSIM (Step 3). Feasible solutions that improve the depleted streams are listed and screened qualitatively against technical, economical, and environmental criteria (Steps 4 and 5). Effectiveness of the remaining 14 feasible alternatives are then analyzed using SWAT (Step 6) and alternative evaluation index (AEI) and their priority ranks are determined against an evaluation criterion that uses the concept of pressure, state, and response (Step 7). 相似文献
975.
Microbubble suspensions were generated as an oxygen carrier for aerobic biodegradation, and their flow characteristics in porous media were investigated. Commercial surfactants including sodium dodecyl sulfate (SDS), and dodecylethyldimethylammonium bromide (DEDAB), saponin (a natural surfactant), and collagen (a protein hydrolysate) were examined as base materials for generating microbubble suspensions. Among them, 2×CMC (critical micellar concentration) of SDS, DEDAB, and saponin developed microbubble suspensions with the highest gas hold‐up and half‐drainage time. Visualization of the flow patterns in sand showed that the microbubble suspensions were separated into a liquid and gas phase directly after injection, showing much faster movement of liquid phase flow. The gas front of the microbubble suspensions flowed in a plug‐flow manner, particularly in cases of SDS and DEDAB. The experimental results from both homogeneous and heterogeneous cells confirmed that the microbubble flow could overcome the heterogeneity in porous media. However, the plug‐flow characteristics and flow propagation of the microbubble suspensions to the low‐permeability zone was accompanied by a large pressure drop, which needs to be considered for future field application. 相似文献
976.
The transport and dilution dynamics of power-plant thermal effluent were measured for 10 consecutive days, between 25 June and 4 July 2006, by concurrently mapping the daily distributions of seawater temperature and concentrations of deliberately released sulfur hexafluoride (SF(6)) within the tidal Kwangyang Bay on the southern coast of Korea. Estimates of the daily extent of the thermal plume based on temperature and SF(6) data showed distinct differences. These differences were particularly pronounced on sunny days during which solar radiation significantly heated river or bay waters moving across the tidal flats; in these cases, the estimates based on seawater temperature data were consistently greater than those based on SF(6) data, indicating considerable overestimates of the extent of the thermal plume when temperature data were used. The present results indicate that the concurrent use of seawater temperature and SF(6) data is a powerful method in determining the extent of thermal plumes, particularly for shallow areas in which the effects of solar heating lead to large uncertainties in temperature-based estimates. 相似文献
977.
PAHs contamination and bacterial communities in mangrove surface sediments of the Jiulong River Estuary, China 总被引:2,自引:0,他引:2
Sixteen sediment samples collected from eight transects in a mangrove swamp of the Jiulong River Estuary, Fujian, China were investigated for their content of polycyclic aromatic hydrocarbons (PAHs) and the biodegradation potential of the indigenous microorganisms. The bacterial community structures in the mangrove sediments and in enrichment cultures were also investigated. The results showed that the total PAHs concentration of mangrove sediments ranged from 280 to 1074 ng g(-1) dry weight, that the PAHs composition pattern in the mangrove sediments was dominated by high molecular weight PAH components (4-6 rings), and that Benzo[ghi]perylene and Indeno[1,2,3-cd]pyrene were the most dominant at different stations. Abundant PAH-degrading bacteria were found in all the stations, the values of phenanthrene-degrading bacteria ranged from 5.85 x 10(4) to 7.80 x 10(5) CFU g(-1) dry weight, fluoranthene-degrading bacteria ranged from 5.25 x 10(4) to 5.79 x 10(5) CFU g(-1) dry weight, pyrene-degrading bacteria ranged from 3.10 x 10(4) to 6.97 x 10(5) CFU g(-1) dry weight and the benzo(a)pyrene-degrading bacteria ranged from 5.25 x 10(4) to 7.26 x 10(5) CFU g(-1) dry weight. DGGE analysis of PCR-amplified 16S rDNA gene fragments confirmed that there was a remarkable shift in the composition of the bacterial community due to the addition of the different model PAH compound phenanthrene (three ring PAH), fluoranthene(four ring PAH), pyrene(four ring PAH) and benzo(a)pyrene(five ring PAH) during enrichment batch culture. Eleven strains were obtained with different morphology and different degradation ability. The presence of common bands for microbial species in the cultures and in the native mangrove sediment DNA indicated that these strains could be potential in situ PAH-degraders. 相似文献
978.
Jee-Hyun Jung So-Jueng Kim Taek-Kyun Lee Won Joon Shim Seonock Woo Dae-Jung Kim Chang-Hee Han 《Marine pollution bulletin》2008,57(6-12):599
The purpose of this study was to compare enzymatic biomarker activities in fish caged at two sites, Masan Bay (contaminated) and Haeguemgang (reference). In the present study, ethoxyresorufin O-deethylase (EROD), brain acetyl cholinesterase (bAChE), muscle acetyl cholinesterase (mAChE) and butyryl cholinesterase (mBChE) in caged rockfish (Sebastes schlegeli) were measured 0, 1, 3, 7, 14, 21 and 30 days after caging. The level of CYP1A mRNA and Protein expression was induced higher in Masan Bay at 1, 3, 7, 14 and 30 days after caging. EROD activity in the caged fish was significantly higher in Masan Bay than in Haeguemgang 3 and 7 days after caging, but not at 14 and 30 days after caging. bAChE activity was significantly inhibited at 7 and 14 days after caging in Masan Bay. However, mBChE activity was not significantly inhibited during the experiment. Taken together, the data suggest that the caged fish were exposed, at least transiently, to CYP1A inducers and ChE inhibitors, which is consistent with our previous observations. 相似文献
979.
HaiLin Wang YaHui Zhuang ZhengPing Hao MeiQiu Cao JinXian Zhong XiaoKe Wang Thi Kim Oanh Nguyen 《中国科学D辑(英文版)》2008,51(7):1013-1020
Biomass energy sources are still popular in the rural areas of developing countries for cooking and space heating. Since the incomplete combustion of agricultural residues in home-made ranges might lead to both outdoor and indoor air pollution and cause potential health threat to the rural population, we monitored the ambient levels of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) at a typical rural site. Ambient particulate PAH samples (PM2.5 and PM10) were taken during both cooking and non-cooking periods. Source emission monitoring was also conducted for both improved and tra- ditional cooking stoves used in the area. Ambient PAHs had a significant increase during the cooking periods and varied from 72.1 to 554.4 ng/m3. The highest total PAH levels were found during the supper cooking time, in which five- and six-ring species accounted for a large proportion. The observed PAH levels during cooking periods at this rural site were even higher than those in urban areas. A good correlation was found between the benzo[a]pyrene level and the total PAH concentration (r=0.98), making benzo[a]pyrene a potential molecular marker for PAH pollution in the rural areas, where bio- mass burning is typical. The profiles of the particulate PAHs in both ambient air and source emissions showed a high proportion of high molecular-mass PAHs. In addition, emission factors of 16 PAHs from an improved household stove were found to be significantly lower than those from traditional stoves used in China and in other Asian countries. 相似文献
980.
S. Kim Juniper David F. Bird Melanie Summit Maria Pong Vong Edward T. Baker 《Deep Sea Research Part II: Topical Studies in Oceanography》1998,45(12):2739-2749
This study presents first-time observations of bacterial and viral abundances in hydrothermal event plumes. Two water-column event plumes were formed in conjunction with seismic events and seafloor volcanic eruptions on the northern Gorda Ridge in February–March 1996. Epifluorescence counts of bacteria and viruses were performed on water samples from 3 successive cruises staged in the 10–90 days that followed the onset of seismicity. Relative to background seawater at these 1800–3200 m depths, bacterial abundance was enhanced by 2–3 fold within both event plumes. In contrast, viral numbers were below background seawater values in the younger and more intense of the two event plumes (EP96A), and enhanced in the other (EP96B). Changes in viral abundance may be a secondary response to that of plume bacteria as well as being influenced by particle formation and precipitation within the plumes. Lower bacteria/heat, virus/heat and virus/bacteria ratios in EP96A versus EP96B confirm distinct differences in the microbial response to event plume formation, possibly related to observed differences in plume chemistry. 相似文献