Arctic mercury depletion and its quantitative link with halogens     

Huiting Mao  Robert W. Talbot  Barkley C. Sive  Su Youn Kim  Donald R. Blake  Andrew J. Weinheimer 《Journal of Atmospheric Chemistry》2010,65(2-3):145-170

Gas phase elemental mercury (Hg°) was measured aboard the NASA DC-8 research aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign conducted in spring 2008 primarily over the North American Arctic. We examined the vertical distributions of Hg° and ozone (O₃) together with tetrachloroethylene (C₂Cl₄), ethyne (C₂H₂), and alkanes when Hg°- and O₃-depleted air masses were sampled near the surface (<1 km). This study suggests that Hg° and O₃ depletions commonly occur over linear distances of ~20–200 km. Horizontally there was a sharp decreasing gradient of ~100 ppqv in Hg° over <10 km in going from the bay near Ellesmere Island to the frozen open ocean. There was a distinct land-ocean difference in the vertical thickness of the Hg°-depleted layer – being variable but around a few 100 meters over the ocean whereas occurring only very near the surface over land. Data support that atmospheric mercury depletion events are driven by Hg° reactions with halogen atoms. Derived from data collected aboard the DC-8, we present mathematical expressions giving the rates of Hg° and O₃ depletions as a function of the radical concentrations. These relationships can be a useful metric to evaluate models that attempt to reproduce springtime Arctic Hg° and/or O₃ depletion events, and they can also be employed to obtain order-of-magnitude estimates of radical concentrations and the ratio [Br]/[Cl].  相似文献   

The temporal and spatial variability of the Yellow Sea Cold Water Mass in the southeastern Yellow Sea, 2009-2011   总被引：1，自引：1，他引：0  

OH Kyung-Hee  LEE Seok  SONG Kyu-Min  LIE Heung-Jae  KIM Young-Taeg 《海洋学报(英文版)》2013,32(9):1-10

The Yellow Sea Cold Water Mass(YSCWM) is one of the important water mass in the Yellow Sea(YS).It is distributed in the lower layer in the Yellow Sea central trough with the temperature less than 10 C and the salinity lower than 33.0.To understand the variability of the YSCWM,the hydrographic data obtained in April and August during 2009–2011 are analyzed in the southeastern Yellow Sea.In August 2011,relatively warm and saline water compared with that in 2009 and 2010 was detected in the lower layer in the Yellow Sea central area.Although the typhoon passed before the cruise,the salinity in the Yellow Sea central trough is much higher than the previous season.It means that the saline event cannot be explained by the typhoon but only by the intrusion of saline water during the previous winter.In April 2011,actually,warm and saline water(T >10 C,S >34) was observed in the deepest water depth of the southeastern area of the Yellow Sea.The wind data show that the northerly wind in 2011 winter is stronger than in 2009 and 2010 winter season.The strong northerly wind can trigger the intrusion of warm and saline Yellow Sea Warm Current.Therefore,it is proposed that the strong northerly wind in winter season leads to the intrusion of the Yellow Sea Warm Current into the Yellow Sea central trough and influenced a variability of the YSCWM in summer.  相似文献   

Mercury concentrations in environmental media at a hazardous solid waste landfill site and mercury emissions from the site     

Young-Ji Han  Pyung-Rae Kim  Gang-San Lee  Jae-In Lee  Seam Noh  Seok-Min Yu  Kwang-Su Park  Kwang-Seol Seok  Hyuk Kim  Young-Hee Kim 《Environmental Earth Sciences》2017,76(10):361

Mercury (Hg) concentrations in air, effluent water, landfill gas, leachate, groundwater, and soil at a hazardous solid waste landfill site in Korea were measured along with air–soil surface Hg exchange fluxes at the site. The concentrations and fluxes were considerably higher than have been found elsewhere in Korea. Gaseous Hg concentrations in the air peaked during the day, coinciding with Hg being released from the landfill surface. This suggests that air–soil exchange increased the Hg concentrations in the atmosphere. The air–soil exchange flux increased abruptly when solar radiation reached the soil surface. The Hg flux peaked about 3 h before the solar radiation peaked, possibly because reducible Hg was abundant at the soil surface. The Hg emission flux activation energy (E _a) was low, indicating that the Hg species present and Hg–soil binding were probably not as important (because of the high Hg content of the soil) as in previous studies. The methylmercury to total Hg ratios in the discharged effluent, groundwater, and leachate was clearly higher than typically found in coastal water and freshwater, suggesting bacteria caused active methylation to occur under the reducing conditions in the anaerobic landfill. The results suggested that considerable amounts of Hg are probably transported from the landfill to nearby environmental media and that this will continue if waste with a high Hg content continues to be added to the landfill without being pretreated.  相似文献   

Potential for heavy metal (copper and zinc) removal from contaminated marine sediments using microalgae and light emitting diodes     

Hyeong Kyu Kwon  Jin Young Jeon  Seok Jin Oh 《Ocean Science Journal》2017,52(1):57-66

The effects of monochromatic (blue, yellow and red LED) and mixed wavelengths (fluorescent lamp) on the adsorption and absorption of Cu and Zn by Phaeodactylum tricornutum, Nitzschia sp., Skeletonema sp., and Chlorella vulgaris were investigated. In addition, we confirmed the potential of microalgae for phytoremediation of these heavy metals from contaminated marine sediment by using microcosm experiments that incorporated LEDs and semipermeable membrane (SPM) tube containing microalgae. Among the four microalgae, C. vulgaris grown under red LED exhibited the highest Cu and Zn removal with values of 17.5 × 10^-15 g Cu/cell and 38.3 × 10^-15 g Zn/cell, respectively. Thus, C. vulgaris could be a useful species for phytoremediation. In the microcosm experiments with SPM containing C. vulgaris, the highest Cu and Zn removal from sediment and interstitial water showed under red LED. Therefore, phytoremediation using LED and SPM tube containing microalgae could be utilized as an eco-friendly technique for remediating contaminated marine sediment.  相似文献   

Erratum to: Effects of environmental and biological conditions on the recruitment and growth of the Manila Clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> on the West Coast of Korea     

Sang Lyeol Kim  Soon Hyun Kwon  Hyung-Gon Lee  Ok Hwan Yu 《Ocean Science Journal》2017,52(1):165-165

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New polymorphic microsatellite markers derived from hemocyte cDNA library of Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> challenged by the protozoan parasite <Emphasis Type="Italic">Perkinsus olseni</Emphasis>     

Hyun-Sil Kang  Hyun-Ki Hong  Kyung-Il Park  Moonjae Cho  Seok-Hyun Youn  Kwang-Sik Choi 《Ocean Science Journal》2017,52(1):139-146

Manila clam Ruditapes philippinarum is one of the most important benthic animals in the coastal north Pacific region, where clam populations have been mixed genetically through trade and aquaculture activities. Accordingly, identification of the genetically different clam populations has become one of the most important issues to manage interbreeding of the local and introduced clam populations. To identify genetically different populations of clam populations, we developed 11 expressed sequence tag (EST)-microsatellite loci (i.e., simple sequence repeat, SSR) from 1,128 clam hemocyte cDNA clones challenged by the protozoan parasite Perkinsus olseni. Genotype analysis using the markers developed in this study demonstrated that clams from a tidal flat on the west coast contained 6 to 19 alleles per locus, and a population from Jeju Island had 4 to 20 alleles per locus. The expected heterozygosity of the 2 clam populations ranged from 0.472 to 0.919 for clams from the west coast, and 0.494 to 0.919 for clams from Jeju Island, respectively. Among the 11 loci discovered in this study, 7 loci significantly deviated from the Hardy-Weinberg equilibrium after Bonferroni correction. The 5 loci developed in this study also successfully amplified the SSRs of R. variegatus, a clam species taxonomically very close to R. philippinarum, from Hong Kong and Jeju Island. We believe that the 11 novel polymorphic SSR developed in this study can be utilized successfully in Manila clam genetic diversity analysis, as well as in genetic discrimination of different clam populations.  相似文献   

Analysis of microwave ducting in an inhomogeneous troposphere     

Se Hyun Cho  James R. Wait 《Pure and Applied Geophysics》1978,116(6):1118-1142

Summary Theory for the transmission of electromagnetic waves in a non-uniform troposphere is presented. The atmospheric refractive index is allowed to vary both with height and range. The formulation is facilitated by the fact that the field within a piecewise (laterally) uniform section can be represented by a discrete sum of modes that are orthogonal in the transverse plane. Using the appropriate radial wave functions, mode conversion at a junction between two laterally uniform sections is considered. The analysis is then extended to multi-section structures. A few typical profiles of refractive index are examined numerically for both uniform and non-uniform models. One of the important findings is that the lateral non-uniformities in an elevated duct will enhance the overall transmission for ground-based transmitting and receiving antennas.  相似文献   

Surface roughness signatures of summer arctic snow-covered sea ice in X-band dual-polarimetric SAR     

Hyangsun Han  Jae-In Kim  Chang-Uk Hyun  Seung Hee Kim  Jeong-Won Park  Young-Joo Kwon 《地理信息系统科学与遥感》2020,57(5):650-669

ABSTRACT

Surface roughness of sea ice is primary information for understanding sea ice dynamics and air–ice–ocean interactions. Synthetic aperture radar (SAR) is a powerful tool for investigating sea ice surface roughness owing to the high sensitivity of its signal to surface structures. In this study, we explored the surface roughness signatures of the summer Arctic snow-covered first-year sea ice in X-band dual-polarimetric SAR in terms of the root mean square (RMS) height. Two ice campaigns were conducted for the first-year sea ice with dry snow cover in the marginal ice zone of the Chukchi Sea in August 2017 and August 2018, from which high-resolution (4 cm) digital surface models (DSMs) of the sea ice were derived with the help of a terrestrial laser scanner to obtain the in situ RMS height. X-band dual-polarimetric (HH and VV) SAR data (3 m spatial resolution) were obtained for the 2017 campaign, at a high incidence angle (49.5°) of TerraSAR-X, and for the 2018 campaign, at a mid-incidence angle (36.1°) of TanDEM-X 1–2 days after the acquisition of the DSMs. The sea ice drifted during the time between the SAR and DSM acquisitions. As it is difficult to directly co-register the DSM to SAR owing to the difference in spatial resolution, the two datasets were geometrically matched using unmanned aerial vehicle (4 cm resolution) and helicopter-borne (30 cm resolution) photographs acquired as part of the ice campaigns. A total of five dual-polarimetric SAR features―backscattering coefficients at HH and VV polarizations, co-polarization ratio, co-polarization phase difference, and co-polarization correlation coefficient ―were computed from the dual-polarimetric SAR data and compared to the RMS height of the sea ice, which showed macroscale surface roughness. All the SAR features obtained at the high incidence angle were statistically weakly correlated with the RMS height of the sea ice, possibly influenced by the low backscattering close to the noise level that is attributed to the high incidence angle. The SAR features at the mid-incidence angle showed a statistically significant correlation with the RMS height of the sea ice, with Spearman’s correlation coefficient being higher than 0.7, except for the co-polarization ratio. Among the intensity-based and polarimetry-based SAR features, HH-polarized backscattering and co-polarization phase difference were analyzed to be the most sensitive to the macroscale RMS height of the sea ice. Our results show that the X-band dual-polarimetric SAR at mid-incidence angle exhibits potential for estimation of the macroscale surface roughness of the first-year sea ice with dry snow cover in summer.  相似文献   

TBT toxicity on the marine microalga Nannochloropsis oculata   总被引：1，自引：0，他引：1  

Sidharthan M  Young KS  Woul LH  Soon PK  Shin HW 《Marine pollution bulletin》2002,45(1-12):177-180

Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l⁻¹) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC₅₀ (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed.  相似文献   

A method of calculating the non‐linear seismic response of a building braced with viscoelastic dampers     

Hyun Choi  Wook‐Bae Kim  Sang‐Jo Lee 《地震工程与结构动力学》2003,32(11):1715-1728

Buildings are continually subject to dynamic loads, such as wind load, seismic ground motion, and even the load from internal utility machines. The recent trend of constructing more flexible high‐rise buildings underscores the importance of including viscoelastic dampers in building designs. Viscoelastic dampers are used to control the dynamic response of a building. If the seismic design is based only on the linear response spectrum, considerable error may occur when calculating the seismic response of a building; rubber viscoelastic dampers show non‐linear hysteretic damping that is quite different from viscous damping. This study generated a non‐linear response spectrum using a non‐linear oscillator model to simulate a building with viscoelastic dampers installed. The parameters used in the non‐linear damper model were obtained experimentally from dynamic loading tests. The results show that viscoelastic dampers effectively reduce the seismic displacement response of a structure, but transmit more seismic force to the structure, which essentially increases its seismic acceleration response. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献