Calcium promotes cadmium elimination as vaterite grains by tobacco trichomes   总被引：1，自引：0，他引：1  

Marie-Pierre Isaure  Géraldine Sarret  Yong-Eui Choi  Sirine C. Fakra  Sébastien Pairis  Stephan Clemens  Alain Manceau 《Geochimica et cosmochimica acta》2010,74(20):5817-5834

In tobacco plants, elimination of Zn and Cd via the production of Ca-containing grains at the top of leaf hairs, called trichomes, is a potent detoxification mechanism. This study examines how Cd is incorporated in these biominerals, and how calcium growth supplement modifies their nature. Scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX), microfocused X-ray diffraction (μ-XRD), and microfocused X-ray absorption near edge structure (μ-XANES) spectroscopy were used to image the morphology of the grains, identify the crystallized mineral phases, and speciate Cd, respectively. The mineralogy of the grains and chemical form of Cd varied with the amount of Ca. When tobacco plants were grown in a nutrient solution containing 25 μM Cd and low Ca supplement (Ca/Cd = 11 mol ratio), most of the grains were oblong-shaped and low-Cd-substituted calcite. When exposed to the same amount of Cd and high Ca supplement (Ca/Cd = 131 mol ratio), grains were more abundant and diverse in compositions, and in total more Cd was eliminated. Most grains in the high Ca/Cd experiment were round-shaped and composed predominantly of Cd-substituted vaterite, a usually metastable calcium carbonate polymorph, and subordinate calcite. Calcium oxalate and a Ca amorphous phase were detected occasionally in the two treatments, but were devoid of Cd. The biomineralization of cadmium and implications of results for Cd exposure of smokers and phytoremediation are discussed.  相似文献   

Relationships between tissue concentrations of paralytic shellfish toxins and antioxidative responses of clams, Ruditapes philippinarum     

Choi NM  Yeung LW  Siu WH  So IM  Jack RW  Hsieh DP  Wu RS  Lam PK 《Marine pollution bulletin》2006,52(5):572-578

  相似文献   

Age Estimation and Growth Performance of the Blackthroat Seaperch,Doederleinia berycoides (Hilgendorf, 1879), in Korean Waters     

Khan  Makidul Islam  Choi  Jung Hwa 《Ocean Science Journal》2021,56(4):385-394

Ocean Science Journal - Age and growth estimations are important fisheries management tools to gain insight into the population structures of commercially important fish species. Despite their...  相似文献   

Application of a fuzzy operator to susceptibility estimations of coal mine subsidence in Taebaek City,Korea   总被引：6，自引：3，他引：3  

Jong-Kuk Choi  Ki-Dong Kim  Saro Lee  Joong-Sun Won 《Environmental Earth Sciences》2010,59(5):1009-1022

Quantitative determination of locations vulnerable to ground subsidence at mining regions is necessary for effective prevention. In this paper, a method of constructing subsidence susceptibility maps based on fuzzy relations is proposed and tested at an abandoned underground coal mine in Korea. An advantage of fuzzy combination operators over other methods is that the operation is mathematically and logically easy to understand and its implementation to GIS software is simple and straightforward. A certainty factor analysis was used for estimating the relative weight of eight major factors influencing ground subsidence. The relative weight of each factor was then converted into a fuzzy membership value and integrated as a subsidence hazard index using fuzzy combination operators, which produced coal mine subsidence susceptibility maps. The susceptibility maps were compared with the reported ground subsidence areas, and the results showed high accuracy between our prediction and the actual subsidence. Based on the root mean square error and accuracy in terms of success rates, fuzzy γ-operator with a low γ value and fuzzy algebraic product operator, specifically, are useful for ground subsidence prediction. Comparing the results of a fuzzy γ-operator and a conventional logistic regression model, the performance of the fuzzy approach is comparative to that of a logistic regression model with improved computational. A field survey done in the area supported the method’s reliability. A combination of certainty factor analysis and fuzzy relations with a GIS is an effective method to determine locations vulnerable to coal mine subsidence.  相似文献   

Transport phenomena in kaolinite clay: Molecular simulation,homogenization analysis and similitude law     

Jung Hae Choi  A. H. M. Faisal Anwar  Katsuyuki Kawamura  Yasuaki Ichikawa 《国际地质力学数值与分析法杂志》2009,33(5):687-707

Kaolinite is a common clay mineral. It is a nanomaterial with a platelet crystalline structure. In order to analyze the behavior of kaolinite, its microscopic structure and material properties must be specified correctly. A molecular dynamics (MD) simulation is used for determining the microscale properties of hydrated kaolinite, and these properties are introduced into a multiscale homogenization analysis (HA). We previously developed such an MD/HA technique to investigate seepage, diffusion, sorption and consolidation in bentonite clay (Proceedings of the Science Basis for Nuclear Waste Management, Davos, Switzerland, vol. XXI. Material Research Society: Warrendale, PA, 1997; 359–366; Eng. Geol. 1999; 54 :21–31; Eng. Geol. 2001; 60 :127–138; Coupled Thermo‐Hydro‐Mechanical‐Chemical Processes in Geo‐systems. Elsevier: Amsterdam, 2005; 457–464). We here apply the method to kaolinite clay to investigate the permeability, diffusion and related similitude law. The obtained results are supported by existing experimental data. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Influence of flow rate and organic carbon content on benzene transport in a sandy soil     

Song‐Bae Kim  Heon‐Cheol Ha  Nag‐Choul Choi  Dong‐Ju Kim 《水文研究》2006,20(20):4307-4316

  相似文献   

The X-ray pulse profile of BG CMi     

Chul-Sung Choi  Tadayasu Dotani  Yonggi Kim  Dongsu Ryu   《New Astronomy》2007,12(8):622-629

We present an analysis of the X-ray data of a magnetic cataclysmic variable, BG CMi, obtained with ROSAT in March 1992 and with ASCA in April 1996. We show that four peaks clearly exist in the X-ray pulse profile, unlike a single peak found in the optical profile. The fluxes of two major pulses are 2–5 times larger than those of two minor pulses. The fraction of the total pulsed flux increases from 51% to 85% with increasing energy in 0.1–2.0 keV, whereas it decreases from 96% to 22% in 0.8–10 keV. We discuss the implications of our findings for the origin of the pulse profile and its energy dependence.  相似文献   

Homogenization framework for three‐dimensional elastoplastic finite element analysis of a grouted pipe‐roofing reinforcement method for tunnelling     

G. J. Bae  H. S. Shin  C. Sicilia  Y. G. Choi  J. J. Lim 《国际地质力学数值与分析法杂志》2005,29(1):1-24

This paper deals with the grouted pipe‐roofing reinforcement method that is used in the construction of tunnels through weak grounds. This system consists on installing, prior to the excavation of a length of tunnel, an array of pipes forming a kind of ‘umbrella’ above the area to be excavated. In some cases, these pipes are later used to inject grout to strengthen the ground and ‘connect’ the pipes. This system has proven to be very efficient in reducing tunnel convergence and water inflow when tunnelling through weak grounds. However, due to the geometrical and mechanical complexity of the problem, existing finite element frameworks are inappropriate to simulate tunnelling using this method. In this paper, a mathematical framework based on a homogenization technique to simulate ‘grouted pipe‐roofing reinforced ground’ and its implementation into a 3‐D finite element programme that can consider stage construction situations are presented. The constitutive model developed allows considering the main design parameters of the problem and only requires geometrical and mechanical properties of the constituents. Additionally, the use of a homogenization approach implies that the generation of the finite element mesh can be easily produced and that re‐meshing is not required as basic geometrical parameters such as the orientation of the pipes are changed. The model developed is used to simulate tunnelling with the grouted pipe‐roofing reinforcement method. From the analyses, the effects of the main design parameters on the elastic and the elastoplastic analyses are considered. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

The effect of ozone and aerosols on the surface erythemal UV radiation estimated from OMI measurements     

Joonsuk Lee  Won Jun Choi  Deok Rae Kim  Seung-Yeon Kim  Chang-Keun Song  Jun Suk Hong  Youdeog Hong  Sukjo Lee 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(3):271-278

Surface erythemal UV radiation is mainly affected by total column ozone, aerosols, clouds, and solar zenith angle. The effect of ozone on the surface UV radiation has been explored many times in the previous studies due to the decrease of ozone layer. In this study, we calculated the effect of aerosols on the surface UV radiation as well as that of ozone using data acquired from Ozone Monitoring Instrument (OMI). First, ozone, aerosol optical depth (AOD), and surface erythemal UVB radiation measured from satellite are compared with those from ground measurements. The results showed that the comparison for ozone was good with r ² of 0.92. For aerosol, there was difference between satellite measurements and surface measurements due to the insufficient information on aerosol in the retrieval algorithm. The r ² for surface erythemal UV radiation was high (～0.94) but satellite measurements showed about 30% larger values than surface measurements on average by not considering the effect of absorbing aerosols in the retrieval process from satellite measurements. Radiative amplification factor (RAF) is used to access the effect of ozone and aerosol quantitatively. RAF for ozone was 0.97～1.49 with solar zenith angle. To evaluate the effect of aerosol on the surface UV radiation, only clear-sky pixel data were used and solar zenith angle and total column amount of ozone were fixed. Also, RAF for aerosol was assessed according to the single scattering albedo (SSA) of aerosols. The results showed that RAF for aerosol with smaller SSA (< 0.90) was larger than that for with larger SSA (> 0.90). The RAF for aerosol was 0.09～0.22 for the given conditions which was relatively small compared to that for ozone. However, considering the fact that aerosol optical depth can change largely in time and space while the total column amount of ozone does not change very much, it needs to include the effect of aerosol to predict the variations of surface UV radiation more correctly.  相似文献   

Biofilm: A crucial factor affecting the settlement of seaweed on intertidal rocky surfaces     

Sang Rul Park  Yun Hee Kang  Chang Geun Choi 《Estuarine, Coastal and Shelf Science》2011

We hypothesized that the presence of biofilm accelerated the settlement of dominant seaweed species and maintained high levels of species richness by regulating the blooming of particular species on an intertidal rocky shore. The coverage and species richness of macroalgae on sterile and cleared substrates (225 cm²) were measured to investigate the effects of biofilm on the settlement of macroalgae in intertidal zones at Noryang, Songmoon, and Sangnam in Gawngyang Bay on the southern coast of the Korean peninsula. Green algae coverage on cleared substrates was significantly higher than that on sterile substrates at both Noryang and Songmoon during the study period. This suggests that the presence of biofilm enhances the settlement of green algae by providing various habitat structures and, consequently, may lead to serious ‘green tide’ events. However, the coverage of algae other than green algae and algal species richness on cleared substrates remained high at Sangnam during the experimental period. Biofilm facilitated the settlement of macroalgae and inhibited the blooming of specific algae by inducing inter-specific space competition. Therefore, biofilm plays an important role on seaweed assemblages on intertidal rocky shores by accelerating the settlement of seaweed.  相似文献