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排序方式: 共有323条查询结果,搜索用时 139 毫秒
51.
Cheol-Hee Kim Lim-Seok Chang Jeong-Soo Kim Fan Meng Mizuo Kajino Hiromasa Ueda Yuanhang Zhang Hye-Young Son Youjiang He Jun Xu Keiichi Sato Chang-Keun Song Soo-Jin Ban Tatsuya Sakurai Zhiwei Han Lei Duan Suk-Jo Lee Shang-Gyoo Shim Young Sunwoo Tae-Young Lee 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(4):399-411
Three comprehensive acid deposition models were used to simulate the sulfur concentrations over northeast Asia over the period covering entire year of 2002, and discussed the aggregated uncertainties and discrepancies of the three models. The participating models are from the countries participating in the project of Longrange Transboundary Air Pollutants in Northeast Asia (LTP): China, Japan and Korea. The Eulerian Model-3/CMAQ (by China), Regional Air Quality Model (RAQM, by Japan), and Comprehensive Acid Deposition Model (CADM, by Korea) were employed by each country with common emissions data established by the administrative agencies of China, Japan and Korea. The episodic simulation results between 1 to 15, March 2002 are also presented, during which aircraft measurements were carried out over the Yellow sea. The episodic results show both a wide short-term variability in simulations against measurements, and maximum concentration differences of 3~5 times among the three models, requiring that further attention before confidence among the three models can be claimed for short-term simulations. However, the year-long cumulative simulations showed almost the same general features, with lower aggregated uncertainties between the three models, produced by the long term integration over northeast Asia. 相似文献
52.
Current practice for estimating water inflow rate relies mostly on analytical solutions which assume a homogeneous, isotropic porous medium around a tunnel. Field measurements indicate that current engineering practice does not consistently make adequate estimate of ground-water flow into a tunnel during excavation due to various factors that analytical solutions do not properly take into account. Among the various factors affecting ground-water flow, the significance of a highly pervious feature located near the tunnel is discussed in this research. The highly pervious feature, which is located near an underground opening and connected to a large source of water, can provide a path for relatively high-head water to the joints intersecting the opening. This paper describes the influence of a highly pervious feature on the ground-water flow regime around a tunnel and the change of inflow rate as the tunnel approaches a highly pervious feature. 相似文献
53.
Ellen M. Moon 《Geochimica et cosmochimica acta》2011,75(21):6705-6719
Bacteria are very efficient sorbents of trace metals, and their abundance in a wide variety of natural aqueous systems means biosorption plays an important role in the biogeochemical cycling of many elements. We measured the adsorption of Cu(II) to Bacillus subtilis as a function of pH and surface loading. Adsorption edge and XAS experiments were performed at high bacteria-to-metal ratio, analogous to Cu uptake in natural geologic and aqueous environments. We report significant Cu adsorption to B. subtilis across the entire pH range studied (pH ∼2-7), with adsorption increasing with pH to a maximum at pH ∼6. We determine directly for the first time that Cu adsorbs to B. subtilis as a (CuO5Hn)n−8 monodentate, inner-sphere surface complex involving carboxyl surface functional groups. This Cu-carboxyl complex is able to account for the observed Cu adsorption across the entire pH range studied. Having determined the molecular adsorption mechanism of Cu to B. subtilis, we have developed a new thermodynamic surface complexation model for Cu adsorption that is informed by and consistent with EXAFS results. We model the surface electrostatics using the 1pK basic Stern approximation. We fit our adsorption data to the formation of a monodentate, inner-sphere RCOOCu+ surface complex. In agreement with previous studies, this work indicates that in order to accurately predict the fate and mobility of Cu in complex biogeochemical systems, we must incorporate the formation of Cu-bacteria surface complexes in reactive transport models. To this end, this work recommends log K RCOOCu+ = 7.13 for geologic and aqueous systems with generally high B. subtilis-to-metal ratio. 相似文献
54.
Young Baek Son Joji Ishizaka Jong-Chul Jeong Hyun-Choel Kim Taehee Lee 《Ocean Science Journal》2011,46(4):239-263
To distinguish true red tide water (particularly Cochlodinium polykrikoides blooms) from non-red tide water (false satellite high chlorophyll water) in the South Sea of Korea, we developed a systematic
classification method using spectral information from MODIS level products and applied it to five different harmful algal
bloom events. Red tide and nonred tide waters were classified based on four different criteria. The first step revealed that
the radiance peaks of potential red tide water occurred at 555 and 678 nm. The second step separated optically different waters
that were influenced by relatively low and high contributions of colored dissolved organic matter (CDOM) (including detritus)
to chlorophyll. The third and fourth steps discriminated red tide water from non-red tide water based on the blue-to-green
ratio in areas with lower and higher contributions of CDOM to chlorophyll, respectively. After applying the red tide classification
(using the four criteria), the spectral response of the red tide water, which is influenced by pigment concentration, showed
different slopes for the blue and green bands (lower slope at blue bands and higher slope at green bands). The opposite result
was found for non-red tide water, due to decreasing phytoplankton absorption and increasing detritus/CDOM absorption at blue
bands. The results were well matched with the discoloration of water (blue to dark red/brown) and delineated the areal coverage
of C. polykrikoides blooms, revealing the nature of spatial and temporal variations in red tides. This simple spectral classification method
led to increase user accuracy for C. polykrikoides and non-red tide blooms (>46% and >97%) and provided a more reliable and robust identification of red tides over a wide range
of oceanic environments than was possible using chlorophyll a concentration, chlorophyll anomaly, fluorescence analysis, or proposed red tide detection algorithms. 相似文献
55.
Deok Hyun Moon Da-Yeon Oh Mahmoud Wazne Jeong-Hun Park 《Environmental Earth Sciences》2013,69(8):2721-2729
As and Pb-contaminated sediment obtained from the Nakdong Lake and Yeongsan River in the Republic of Korea was stabilized using a combination of calcined oyster shell (COS), waste cow bone (WCB) and coal mine drainage sludge (CMDS). The effectiveness of the stabilization treatment was evaluated using the Korean Standard Test (KST). The KST tests were performed using 1 N HCl extraction fluid for As and 0.1 N HCl extraction fluid for Pb. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) analyses were performed to investigate the mechanism responsible for As and Pb immobilization upon treatment. The treatment results showed that effective stabilization of As and Pb-contaminated sediment was obtained. Specifically, 10 wt% COS–5 wt% CMDS was the best treatment for As immobilization and 5 wt% COS–5 wt% WCB was the best treatment for Pb immobilization. The COS–WCB treatment outperformed the COS–CMDS treatment in immobilizing Pb in the contaminated sediment. SEM–EDX results indicated that Pb immobilization was strongly associated with Ca, Si, Al and P while As immobilization was strongly associated with Fe and O. Therefore, utilization of COS, WCB and CMDS is beneficial for the stabilization of contaminated sediment. 相似文献
56.
Simultaneous stabilization of arsenic, lead, and copper in contaminated soil using mixed waste resources 总被引:1,自引:0,他引:1
Keun-Young Lee Deok Hyun Moon Sang-Ho Lee Kyoung-Woong Kim Kyung-Hoon Cheong Jeong-Hun Park Yong Sik Ok Yoon-Young Chang 《Environmental Earth Sciences》2013,69(6):1813-1820
In the present study, stabilization treatment using waste resource stabilizers was performed for soil contaminated with As and heavy metals (Pb and Cu). Calcined oyster shell (COS) and coal mine drainage sludge (CMDS) were used as a mixed stabilizing agent for a wet-curing duration of 28 days. After the stabilization treatment, the treatment process efficiency was evaluated by the results of various batch- and column-leaching tests. Neutral and weak acid extraction methods, such as water-soluble extraction and SPLP, did not exhibit satisfactory results for heavy metal stabilization, even if they showed very low leachability. On the other hand, TCLP and 0.1 M HCl extraction showed that the stabilizers significantly reduced the amount of heavy metals leached from the soil, which strongly supports the thesis that the stabilization treatment is efficient in the acidic leaching conditions that were explored. Specifically, in the 0.1 M HCl extraction, the reduction efficiencies of As, Pb, and Cu leachings were more than 90 %, compared with control experiments. This study demonstrates that the application of waste resources for the stabilization of As and heavy metals is feasible. However, some limitations observed in the experiments should be considered in future studies, such as the mobilization of alkali-soluble elements, and in particular, exchangeable fractions of Cu. In addition, the treatment efficiency can be evaluated by different leaching methods, which suggests that multidirectional approaches are required for the proper evaluation of stabilization treatment. 相似文献
57.
利用差分合成孔径雷达干涉测量技术(DInSAR)获取长白山地区的形变场.结果显示1995~1998年期间,位于长白山东南侧的间白山火山存在6~12 cm的视线向形变,而长白山天池火山处于平静期,没有明显形变.利用2002~2003年的GPS和水准获取的形变数据,分别采用Mogi单源、双源模型反演了长白山地区火山的岩浆囊参数.其中双源模型拟合效果较为理想,两个点源一个位于长白山天池老火山口下方7.9 km处,另一个位于间白山火山下方5.5 km处.对双源模型反演得到的岩浆囊参数进行适当调整,拟合得到与InSAR形变场基本吻合的结果.上述研究结果表明长白山地区火山活动存在时间上的间歇性和空间上的迁移性,为进一步研究长白山地区火山活动机制提供了参考和依据. 相似文献
58.
The Changjiang diluted water (CDW) around Jeju Island between 2002 and 2006 in response to external forcings, such as wind, tidal forcing and low river discharge, is studied using a three-dimensional model. The model results suggest that wind largely determines spatial differences of CDW and the freshwater export toward Jeju Island between two years. In 2006, when northwestward wind blows during mid June to mid August, the wind-induced Ekman flow causes a broad northeastward extension of CDW and carries a significant amount of freshwater northeastward Jeju Island in August. On the other hand, in 2002 northward wind during mid July to early August drives the CDW to the southwest of Jeju Island, and thereafter the CDW is mainly advected northeastward along the Cheju Current during mid August when the wind becomes weak. Therefore, the amount of freshwater around Jeju Island increases in September, not in August. The response to tidal forcing shows that tide-induced vertical mixing tends to enhance a meander of CDW around Changjiang Bank and shift the CDW flowing into the Yellow Sea southeastward toward Jeju Island. As a result, the amount of freshwater toward Jeju Island becomes larger than that in no-tides case. The summer low river discharge as a flood control scenario has little influence on the spatial behavior of CDW around Jeju Island although the discharge contributes to the amount of freshwater around Jeju Island. 相似文献
59.
Evaluation of heavy metal contamination and implication of multiple sources from Hunchun basin, northeastern China 总被引:1,自引:0,他引:1
J.-W. Moon H.-S. Moon N.-C. Woo J.-S. Hahn J.-S. Won Y. Song X. Lin Y. Zhao 《Environmental Geology》2000,39(9):1039-1052
Present concentrations and distributions of heavy metals through profiles, surface soil, and stream sediment samples in the
Hunchun area, north-eastern China, were investigated to determine the elemental background values. This study also aims to
characterize potentially toxic materials such as pulverized fly ash (PFA) from power stations or ash and slag from coal used
domestically in urban areas, agrochemicals applied inappropriately, and urban sewage sludges from Hunchun City, as well as
to ascertain the possibility of natural enrichment through site characterization by mineralogical and geochemical investigation.
The distribution of contaminants in the alluvial soils (fluvisol) of this area has been influenced by several interacting
factors. The parent alluvial materials from weathered products of amphiboles have made coatings such as ferrihydrite, goethite,
and hematite. This natural inheritance factor is supported by the fact that the concentrations of weak acid-extractable (plant-available)
heavy metals are very low, except for Fe and Mn. However, in agricultural soils and adjacent stream sediments, an anthropogenic
input of Cd, Pb, Ni and Cr by agrochemicals is strongly suggested. Also, F contamination by coal combustion and the dissolution
of F-bearing minerals could cause some future problems. Wide distribution and significantly high concentrations of Cd, Fe,
Mn, and F in soils throughout the combination of pollutants originating from lithogenic and the anthropogenic sources pose
potential problems in utilizing water resources.
Received: 14 June 1999 · Accepted: 27 December 1999 相似文献
60.
Charles J. Moon 《Journal of Geochemical Exploration》1999,65(2):365
The quantitative relation between point source soil geochemical anomalies and their response in stream sediments is linked through the concept of productivity (area × concentration). The equation proposed by Hawkes in 1976 is shown to be a subset of a wider range of equations proposed by Russian workers. These workers introduced two coefficients to account for the contrasting behaviour of different elements and the position of the soil anomaly within the drainage catchment. The calculation of these coefficients requires a series of samples downstream from the ending of anomalous soil input. The concept of productivity has particular application where multiple samples and anomalies are present in catchments. Plotting of productivity allows the discrimination of anomalous areas not detectable from raw element concentrations. The usefulness of these techniques is demonstrated from a small detailed stream sediment survey in NW Scotland. Dispersion from a gossan shows deviation from the Hawkes equation with the result that detailed sampling is required to detect soil anomalies. Plotting productivity allows the detection at the base of major slopes of anomalies that are diluted by upslope sediment. 相似文献