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11.
Theoretical and Applied Climatology - Although atmospheric humidity influences environmental and agricultural conditions, thereby influencing plant growth, human health, and air pollution, efforts... 相似文献
12.
Sorption of U(VI) on Hanford fine sand (HFS) with varying Fe-oxide (especially ferrihydrite) contents showed that U(VI) sorption increased with the incremental addition of synthetic ferrihydrite into HFS, consistent with ferrihydrite being one of the most reactive U(VI) sorbents present in natural sediments. Surface complexation model (SCM) calculations for U(VI) sorption, using only U(VI) surface-reaction constants obtained from U(VI) sorption data on freshly synthesized ferrihydrite at different pHs, were similar to the measured U(VI) sorption results on pure synthetic ferrihydrite and on HFS with high contents of ferrihydrite (5 wt%) added. However, the SCM prediction using only U(VI) sorption reactions and constants for synthetic ferrihydrite overestimated U(VI) sorption on the natural HFS or HFS with addition of low amounts of added ferrihydrite (1 wt% added). Over-predicted U(VI) sorption was attributed to reduced reactivity of natural ferrihydrite present in Hanford Site sediments, compared to freshly prepared synthetic ferrihydrite. Even though the SCM general composite (GC) approach is considered to be a semi-quantitative estimation technique for contaminant sorption, which requires systematic experimental data on the sorbent–sorbate system being studied to obtain credible SCM parameters, the general composite SCM model was still found to be a useful technique for describing U(VI) sorption on natural sediments. Based on U(VI) batch sorption results, two simple U(VI) monodentate surface species, SO_UO2HCO3 and SO_UO2OH on ferrihydrite and phyllosillicate in HFS, respectively, can be successfully used to describe U(VI) sorption onto Hanford Site sediment contacting varying geochemical solutions. 相似文献
13.
Chang Hoon Jung Ji Yi Lee Junshik Um Seung Soo Lee Yong Pyo Kim 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):19-32
This study investigated the optical properties of aerosols involved in different meteorological events, including smog and Asian dust days. Carbonaceous components and inorganic species were measured in Seoul, Korea between 25 and 31 March 2012. Based on the measurements, the optical properties of aerosols were calculated by considering composition, size distribution, and mixing state of aerosols. To represent polydisperse size distributions of aerosols, a lognormal size distribution with a wide range of geometric mean diameters and geometric standard deviations was used. For the optical property calculations, the Mie theory was used to compute single-scattering properties of aerosol particles with varying size and composition. Analysis of the sampled data showed that the water-soluble components of organic matter increased on smog days, whereas crustal elements increased on dust days. The water content significantly influenced the optical properties of aerosols during the smog days as a result of high relative humidity and an increase in the water-soluble component. The absorption coefficients depended on the aerosol mixture type and the aerosol size distributions. Therefore, to improve our knowledge on radiative impacts of aerosols, especially the regional impacts of aerosols in East Asia, accurate measurements of aerosols, such as size distribution, composition, and mixture type, under different meteorological conditions are required. 相似文献
14.
Wooyong Um Chongxuan Liu Dean A. Moore Kenton A. Rod 《Geochimica et cosmochimica acta》2010,74(18):5155-2979
Contaminated capillary fringe sediments are believed to function as long-term source of U(VI) to Hanford’s 300 Area groundwater uranium plume that discharges to the Columbia River. The deep vadose zone at this site experiences seasonal water table elevation and water compositional changes in response to Columbia River stage. Batch and column desorption experiments of U(VI) were performed on two mildly contaminated sediments from this system that vary in hydrologic position to ascertain their U(VI) release behavior and factors controlling it. Solid phase characterization of the sediments was performed to identify mineralogic and chemical factors controlling U(VI) desorption. Low adsorbed U(VI) concentrations prevented spectroscopic analysis. The desorption behavior of U(VI) was different for the two sediments in spite of similar chemical and textural characteristics, and non-carbonate mineralogy. Adsorption strength and sorbed U(VI) lability was higher in the near-river sediment. The inland sediment displayed low sorbed U(VI) lability (∼10%) and measurable solid-phase carbonate content. Kinetic desorption was observed that was attributed to regeneration of labile U(VI) in the near river sediment, and carbonate mineral dissolution in the inland sediment. The desorption reaction was best described as an equilibrium surface complexation reaction. The noted differences in desorption behavior appear to result from U(VI) contamination and hydrologic history, as well as sediment carbonate content. Insights are provided on the dynamic adsorption/desorption behavior of contaminants in linked groundwater-river systems. 相似文献
15.
Ik Woo Jae Gon Kim Gyoo Ho Lee Hyuck Jin Park Jeong Gi Um 《Environmental Earth Sciences》2013,69(6):1821-1829
Pyrite is a common and abundant sulfidic mineral subject to oxidation. The weathering characteristics of rock-bearing pyrite sometimes impose serious influences on the surrounding environment as the oxidation of pyrite (FeS2) generates acid drainage that results in the acceleration of rock weathering and the discharge of heavy metals into the environment. Such an accelerated weathering of rocks can reduce its mechanical properties and therefore menace the stability of rock structures, such as excavated slopes and tunnels. The evolution of physical properties of rocks and the chemical composition of drainage were evaluated in this study by a weathering test using a double Soxhlet extractor for 1 month in a laboratory setting. Three groups of biotite gneiss classified according to their pyrite content were used for the Soxhlet extraction experiment (group A with less than 0.1 wt% of pyrite; group B with about 3.3 wt% of disseminated pyrite; group C with about 5.65 wt% of vein type pyrite). The massive groups A and B had limited weathering on the surface; however, group C with the pyrite vein experienced weathering on the surface as well as along the pyrite vein. The weathering type regulated by the occurrence of pyrite apparently controlled the mechanical properties of the rock samples and the chemistry of the drainage. Groups A and B showed no significant quick absorption ratio after the 1-month experiment; however, group C had about 10 % increase in value. The uniaxial compressive strength of the three groups decreased about 20, 10 and 45 % for groups A, B and C, respectively. The mechanical properties of the samples and the chemical compositions of the drainage indicate that the oxidation of pyrite contained in the samples accelerated weathering, resulting in deterioration of mechanical properties of the rocks, and could result in the discharge of heavy metals and acid into the environment with the drainage. 相似文献
16.
Release characteristics of molasses from a well-type barrier system in groundwater: a large test tank study for nitrate removal 总被引：1，自引：1，他引：0
Byung Sun Lee Eungyu Park Jae Yeon Um Kyuyeon Lee Jina Jeong Kyoungphile Nam 《Environmental Earth Sciences》2013,70(1):167-174
A pilot-scale study was conducted to characterize the performance of molasses' release from a well-type barrier system harboring solidifying molasses named slowly released molasses (SRM) as a reactive medium to promote indigenous denitrifying activity. A SRM rod was made by mixing molasses with paraffin wax, cellulose, and silica sands in a cylindrical mold. Two SRM systems harboring 30 and 60 SRM rods, referred to as Systems A and B, respectively, were constructed in a large flow tank (L × W × D = 8 m × 4 m × 2 m) filled with natural sands. These two systems continuously delivered molasses with groundwater flow over 96 days, with decreasing molasses' concentrations ranging from 763 to 95 and 1,150 to 183 mg L?1 as chemical oxygen demand values (COD) for Systems A and B, respectively. From simulation results with an aid of the upscaled mass transfer function (MTF) model, the molasses' mass flux was slowly decreased with time, exhibiting 57, 11, and 3 mg COD day?1 in 10, 100, and 365 days in System A, and 138, 25, and 6 mg COD day?1 in System B, respectively; 90, 70, and 50 % of total molasses' mass remained after 12, 63, and 267 days in System A and 12, 65, and 291 days in System B, respectively. This study demonstrates that SRM system can provide a remedial alternative for long-term in situ treatment of nitrate-contaminated groundwater. 相似文献
17.
Abstract A frequent requirement in post‐construction management of a land pipeline route is to detect revegetation status on a time-sequential basis (usually 5‐10 years). The principal advantage of video is the capacity to provide, in a cost‐effective manner, information required for such a very narrow and long strip target utilising the narrow view angle and dynamic stereo coverage. This paper reports that a video strip monitoring technique requiring solely end lap has been specifically developed with focus on such a narrow and long strip target (e.g. 20‐30m wide and several hundred km long). Such large‐scale video systems are often discussed as being inadequate for a change‐detection application due to geometric and radiometric calibration problems. In spite of such limitations, changes of major thematic land cover classes, particularly for the rapidly recovered target of a pipeline corridor, could be detected successfully by visual or quantitative methods and through further ‘patch dynamics’ analysis in a GIS environment. The results of this study indicate that such calibration problems are generally not a major drawback in acquiring change‐detection information in a practical operational application which requires mostly generalized thematic mapping of relatively simple classes. The results also indicate that Video Strip Mapping (VSM) could be extensively used for other examples of linear thematic mapping. 相似文献
18.
A comparative study of the adaptive choice of thresholds in extreme hydrologic events 总被引：1，自引：1，他引：0
Myoung-Jin Um Woncheol Cho Jun-Haeng Heo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):611-623
In the hydrologic analysis of extreme events such as precipitation or floods, the data can generally be divided into two types:
partial duration series and annual maximum series. Partial duration series analysis is a robust method to analyze hydrologic
extremes, but the adaptive choice of an optimal threshold is challenging. The main goal of this paper was to determine the
best method for choosing optimal thresholds. Ten semi-parametric tail index estimators were applied to find the optimal threshold
of a 24-h duration precipitation period using data from the Korean Meteorological Administration. The mean square errors of
the 10 estimators were calculated to determine the optimal threshold using a semi-parametric bootstrap method. A modified
generalized Jackknife estimator determined the best performance in this study among the 10 estimators evaluated with regard
to estimating the mean square error of the shape estimator for the generalized Pareto distribution. 相似文献
19.
Local variability in temperature, humidity and radiation in the BaekduDaegan Mountain protected area of Korea 总被引：1，自引：1，他引：0
CHAE Heemun LEE Hyunju LEE Sangsin CHEONG Yukyong UM Gijeung MARK Bryan PATRICK Nathan 《山地科学学报》2012,9(5):613-627
A novel embedded sensor network records changes in key climatic-environmental variables over a range of altitude in the BaekduDaegan Mountain (BDM) of Gangwon Province in Korea, a protected mountain region with unique biodiversity undergoing climate change research. The investigated area is subdivided into three horizontal north-south study areas. Three variables, temperature (T, ℃), relative humidity (RH, %), and light intensity (LI, lumens m -2 , or lux, lx), have been continuously measured at hourly intervals from June, 2010 to September, 2011 using HOBO H8 devices at 10 fixed study sites. These hourly observations are aggregated to monthly, seasonal and annual mean values, and results are summarized to inaugurate a long-term climate change investigation. A region wide T difference in accordance with altitude, or lapse rate, over the interval is calculated as 0.4℃100 m -1 . T lapse rates change seasonally, with winter lapse rates being greater than those of summer. RH is elevated in summer compared to other seasons. LI within forestland is lower during summer and higher during other seasons. The obtained results could closely relate to the vegetation type and structure and the terrain state since data loggers were located in forestland. 相似文献
20.
Estimation of rock mass strength and deformability in 3-D for a 30 m cube at a depth of 485 m at Äspö Hard Rock Laboratory 总被引：2，自引：0，他引：2
P. H. S. W. Kulatilake Jinyong Park Jeong-gi Um 《Geotechnical and Geological Engineering》2004,22(3):313-330
The rock fracture data provided by Swedish Nuclear Fuel and Waste Management Company were used to develop a 3-D stochastic fracture network model for a 30 m cube of Äspö diorite located at a depth of 485 m at Äspö Hard Rock Laboratory, Sweden. This fracture network model was validated. A new procedure is developed to estimate rock block strength and deformability in three-dimensions allowing for the anisotropy and incorporating the inherently statistical fracture geometry for the selected cube. The mean rock mass strength was found to be 47% of the mean intact rock strength of 297 MPa at 485 m depth. The mean rock mass modulus was found to be 51% of the intact rock Young's modulus of 73 GPa. The rock mass Poisson's ratio was found to be 21% higher than the intact rock Poisson's ratio of 0.28. These percentages indicate the level of weakening of the rock mass due to the presence of fractures. The ratio of mean major principal rock mass strength/mean minor principal rock mass strength turned out to be 1.28. The ratio of mean major principal rock mass modulus/mean minor principal rock mass modulus turned out to be 1.21. 相似文献