Evaluating the transport and removal of chromate using pyrite and biotite columns

To remove chromate from a wastewater, a porous permeable reactive barrier system (PRBS), using pyrite and biotite, was adapted. This study included bench‐scale column experiments to evaluate the efficiency of the PRBS and investigate the reaction process. The total chromium concentration of the effluent from the biotite and pyrite columns reached the influent concentration of 0·10 mM after passing through more than 150 pore volumes (PVs) and 27 PVs respectively, and remained constant thereafter. The Cr^VI concentration in the effluent from the biotite column became constant at about 0·08 mM , accounting for approximately 80% of the influent concentration, after passing through 200 PVs. Moreover, in the pyrite column, the Cr^VI concentration remained at about 0·01 mM , 10% of the input level, after passing through 116 PVs. This shows that both columns maintained their levels of chromate reduction once the Cr^VI breakthrough curves (BTCs) had reached the steady state, though the steady‐state output concentration of total chromium had reached the influent level. The variances of the iron concentration closely followed those of the chromium. The observed data for both columns were fitted to the predicted BTCs calculated by CXTFIT, a program for estimating the solute transport parameters from experimental data. The degradation coefficient µ of the total chromium BTCs for both columns was zero, suggesting the mechanisms for the removal of chromate limit the µ of the Cr^VI BTCs. The Cr^VI degradation of the pyrite column (6·60) was much greater than that of the biotite column (0·27). In addition, the Cr^VI retardation coefficient R of the pyrite column (253) was also larger than that of the biotite column (125). The R values for the total chromium BTCs from both columns were smaller than those of the Cr^VI BTC. Whereas the total chromium BTC for the pyrite column showed little retardation (1·5), the biotite column showed considerable retardation (80). The results for the 900 °C heat‐treated biotite column were analogous to those of the control column (quartz sand). This suggests that the heat‐treated biotite played no role in the retardation and removal of hexavalent chromium. The parameters of the heat‐treated biotite were calculated to an R of 1·2 and µ of 0·01, and these values confirmed quantitatively that the heated biotite had little effect on the transport of Cr^VI. These solute transport parameters, calculated by CXTFIT from the data obtained from the column tests, can provide quantitative information for the evaluation of bench‐ or field‐scale columns as a removal technology for Cr^VI in wastewater or contaminated groundwater. Copyright © 2006 John Wiley & Sons, Ltd.     

Evaluation of seismic behaviour of Cheomseongdae using dynamic centrifuge model test

Cheomseongdae is known to be the oldest astronomical observatory in Asia. According to historical records, the Gyeongju area, where Cheomseongdae is located, suffered from numerous medium‐scale earthquakes. Cheomseongdae has a masonry structure, which is apparently vulnerable to horizontal dynamic loads such as earthquakes. However, despite its appearance, features such as the filler of the lower half, inner irregular‐shaped stones which can induce high frictional resistance, eight long horizontal tie stones inside the artefact, and a grid of interlocking headstones increase its resistance to horizontal dynamic loads. Dynamic centrifuge model tests were performed on Cheomseongdae in order to evaluate the seismic response characteristics of this architectural heritage structure. Model tests were executed on two 1/15‐scale models: one which was an exact duplicate of the original Cheomseongdae and the other without the long horizontal tie stones and grid of interlocking headstones. On the basis of the amplification patterns in the time and frequency domains, the differences in seismic behaviour between the two Cheomseongdae models, and a broken stone at the 19th layer during tests, the long horizontal tie stones and headstones were found to increase the seismic resistance within Cheomseongdae and provide a glimpse of the ‘seismic design’ of our ancestors. Copyright © 2014 John Wiley & Sons, Ltd.     

Crown fuel characteristics and carbon emission from Japanese red pine stands burned by crown fire in Mt. Palgong, South Korea

Carbon emissions from forest fires are considered an important factor of ecosystem carbon balance and global climate change. Carbon emissions from Japanese red pine stands (Pinus densiflora S. et Z.) burned by crown fire were estimated at Mt. Palgong in Daegu Metropolitan City, and crown fuel characteristics, including crown bulk density, crown base height, and fuel moisture content of Japanese red pine, were analyzed. Total biomass combusted was calculated by subtracting the biomass of burned stands from that of unburned stands exhibiting similar stand structures and site environments. Ten trees in the unburned area and five trees in the burned area were cut by using direct harvesting techniques to estimate crown layer biomass. All biomass sampled was oven-dried and weighed. The dry weight ratios of stems, branches, and needles were 70%, 21%, and 9%, respectively. The available fuel load susceptible to combustion during the crown fire spread was equivalent to 55% of the crown layer biomass. The crown bulk density was 0.24 kg/ m 3 on average. The estimated amount of CO 2 was 23,454 kg CO 2 /ha for the crown layer. These results will be useful for calculating the amount of CO 2 emitted from forest fires and for developing a forest carbon model in P. densiflora forests.     

Seasonal and spatial distribution of nonylphenol and IBP in Saemangeum Bay, Korea

In order to investigate spatial and temporal distribution of organic pollutants in the Saemangeum Bay, organophosphorus pesticides (10), alkylphenols (8), chlorophenols (2), bisphenol A were analyzed from the surface seawater taken in 2002–2003. Most of the analytes were not detected in all stations except nonylphenol and S-benzyl-O,O-di-isopropyl phosphorothioate (IBP). Concentrations of nonylphenol and IBP ranged from ND to 298 ng/l and from ND to 1840 ng/l, respectively. The high levels of nonylphenol and IBP were found in the estuary areas of Mangyeong and Dongjin River. The levels of nonylphenol and IBP in surface seawater varied through seasons and the high levels of nonylphenol and IBP were in summer season (August). Based on real time monitoring of IBP and on correlation between concentrations of target compounds and contents of salinity in seawater, physical mixing and diffusion of seawater were found to be the major factors that affect the spatial distribution of IBP and nonylphenol in the Saemangeum Bay environment.     

Streamflow simulation and skewness preservation based on the bootstrapped stochastic models

The stochastic model has been widely used for the simulation study. However, there was a difficulty in the reproduction of the skewness of observed series and so the stochastic model for the skewness preservation was appeared. While the skewness in the residuals of the stochastic model has been considered for the skewness preservation this study uses a random resampling technique of residuals from the stochastic models for the simulation study and for the investigation of the skewness coefficient. The main advantage of this resampling scheme, called the bootstrap method is that it does not rely on the assumption of population distribution and this study uses the combined model of the stochastic and bootstrapped models. The stochastic and bootstrapped stochastic (or combined) models are used for the investigations of skewness preservation and of the reproduction of probability density function between the simulated series. The models are applied to the annual and monthly streamflows of Yongdam site in Korea and Yakima river, Washington, USA for the streamflow simulation study then the statistics and probability density functions for the observed and simulated streamflows are compared. As the results the bootstrapped stochastic model reproduces the skewness and probability density function much better than the stochastic model. This evidences suggest that the bootstrapped stochastic model might be more appropriate than the stochastic model for the preservation of skewness and for simulation purposes of the series.     

Multiple Foliations Defined by Different Sillimanite Crystal Habits, Partial Melting and the Late Metamorphic Development of the Cannington Ag-Pb-Zn Deposit, Northeast Australia

A succession of foliations defined by different sillimanite-bearing structural fabrics suggests that the macroscopic, isoclinal synform that dominates the geometry of the Cannington Ag-Pb-Zn deposit, northwest Queensland, Australia formed during D₂. The five foliations in this succession, S₁ to S₅, are defined by aligned sillimanite with habits ranging from individual crystals in S₁ through S₄ to clusters of fibrolite in S₅ in both the matrix and as inclusion trails within garnet and gahnite (Zn-rich spinel) porphyroblasts. S₁, S₃ and S₅ formed as sub-horizontal foliations, whereas S_1a, S₂ and S₄ formed sub-vertically. Foliation intersection/inflexion axes (FIAs) within garnet and gahnite porphyroblasts preserve a succession of trends that shifts from W-E to N-S. This succession indicates that this region experienced N-S followed by W-E bulk crustal shortening. N-S shortening occurred during D₁and D_1a, and W-E shortening occurred from D₂ to D₅. Prismatic and rhombic sillimanite produced during D₁-D₄ accompanied prograde metamorphism to ca. 634 62°C and 4.8 1.3 kbar. The coexistence of fibrous, prismatic and rhombic sillimanite resulted from post peak metamorphic reactivation of the early foliations during D₅. The synformal D₂ fold was intensified during D₄ by W-E bulk shortening. Local partial melting occurred after D₁ in the appropriate bulk rock compositions, based on calculation of P-T pseudosections in the chemical systems KFMASH, KFMASHTO, NCKFMASH and MnNCKFMASH. Zn mineralization related to gahnite growth occurred during D₃ through D₄, and was redistributed by partial melting into structural and rheological sites during D₄ and D₅shearing.     

Adiabatic predictions and observations of cloud droplet spectral broadness

The evolution of cloud droplet size spectra is calculated using an adiabatic condensational growth model. Broadness (e.g., standard deviation of diameter) of cloud droplet spectra in adiabatic cloud parcels was determined to be critically dependent on cloud supersaturation. Although droplet spectra become narrower as growth continues, the rate of narrowing is slower when cloud supersaturation is lower. This actually leads to broader droplet spectra for more continental clouds or for weaker updrafts because both of these conditions are associated with lower cloud supersaturations. More continental type clouds, which have higher concentrations of smaller droplets, were indeed found to have larger dispersions (standard deviation of diameter/mean diameter of cloud droplets). Some of these results were consistent with observations, but the larger dispersions that were much more commonly observed for continental compared to maritime clouds were due almost exclusively to smaller droplets rather than broader droplet distributions. Contrary to the model calculations, typical observations show that cleaner clouds usually have broader droplet spectra. The gaps in magnitude between theory and observations of broadness are significant in all clouds. When cloud parcels that had ascended under different updraft conditions were compared at a constant cloud altitude, parcels with lower updrafts were predicted to have broader droplet spectra with larger mean diameters. This trend of apparent spectral broadening was consistent with observations for some near-adiabatic cloud parcels.     

Dynamics of ecosystems and anthropogenic drivers in the Yellow Sea Large Marine Ecosystem

<正>In the developed world, governance of marine ecological environment is the important part of the national ecological and economic outcome. The Yellow Sea is one of large marine ecosystems in the seas of East Asia, which is an extension of one of the largest continental shelf areas, and forms a huge but shallow sediment body in its south area which is geographically unique in the world. As a region with the most fragile natural environment, unparalleled global ecological significance and...     

A comparative study on a simple two-parameter monthly water balance model and the Kajiyama formula for monthly runoff estimation

ABSTRACT

A two-parameter monthly water balance model to simulate runoff can be used for a water resources planning programme and climate impact studies. However, the model estimates two parameters of transformation of time scale (c) and of the field capacity (SC) by a trial-and-error method. This study suggests a modified methodology to estimate the parameters c and SC using the meteorological and geological conditions. The modified model is compared with the Kajiyama formula to simulate the runoff in the Han River and International Hydrological Programme representative basins in South Korea. We show that the estimated c and SC can be used as the initial or optimal values for the monthly runoff simulation study in the model.

EDITOR M.C. Acreman; ASSOCIATE EDITOR S. Kanae     

Characterization and sources of extractable organic matter from sediment cores of an urban lake (Tasik Perdana), Kuala Lumpur,Malaysia

The extractable organic matter of sediment samples from six sampling sites in Lake Perdana, Kuala Lumpur, was analyzed to characterize the source inputs. The analysis of aliphatic homologous series indicated that terrestrial higher plant waxes can be assigned as the major sources of the identified aliphatic components in the lake sediments. The presence of an unresolved complex mixture of branched and cyclic compounds and a series of hopanes ranging from C₂₇ to C₃₅ reflected the contamination by petroleum residues from urban vehicular emissions brought in by runoff and fallout. The steroids present included stenols and stanols and showed an input of organic matter from higher plants. The detected pentacyclic triterpenoids comprised oleanane, ursane, lupane and friedelane skeletons including unsaturated oxygenated, mono-, di- and triaromatic counterparts. They are recognized as biomarkers for angiosperms. The presence of des-A-triterpenoids and their aromatized derivatives as the major diagenetic products of triterpenoids reflected the degradation of natural organic matter in the sediments occurring under mainly anoxic conditions. In addition, the presence of tetrahymanol and ββ-bishomohopan-32-ol indicated a minor algal/plankton and bacterial input to the sediments.