Distribution and source apportionments of polychlorinated biphenyls (PCBs) in mariculture sediments from the Pearl River Delta, South China   总被引：1，自引：0，他引：1  

Wang HS  Du J  Leung HM  Leung AO  Liang P  Giesy JP  Wong CK  Wong MH 《Marine pollution bulletin》2011,63(5-12):516-522

Surface and core sediments collected from six mariculture farms in the Pearl River Delta (PRD) were analyzed to evaluate contamination levels of polychlorinated biphenyls (PCBs). The ∑PCBs (37 congeners) concentrations ranged from 5.10 to 11.0 ng g(-1) (mean 7.96 ng g(-1)) in surface and 3.19 to 22.1 ng g(-1) (mean 7.75 ng g(-1)) in core sediments, respectively. The concentrations were significantly higher than that measured in the sediments of their corresponding reference sites, whereby the average enrichment percentages were 62.0% and 42.7% in surface and core sediments, respectively. Significant correlations (R2=0.77, p<0.05) of PCB homologue group proportions between fish feeds and surface mariculture sediments suggested that fish feed input was probably the main source for the enrichment of PCBs. Due to the fact that PCBs could be transferred along food chains, PCB contamination in fish feeds and mariculture sediments should not be overlooked.  相似文献   

Assessment of risk of PCDD/Fs and dioxin-like PCBs in marine and freshwater fish in Pearl River Delta, China     

Wei X  Leung KS  Wong MH  Giesy J  Cai ZW  Wong CK 《Marine pollution bulletin》2011,63(5-12):166-171

Fish consumption is known to be beneficial to human health. However since the age of industrialization, the released/disposed chemical pollutants into water systems make fish a source of various environmental toxicants to humans. In oceanic cities with heavy industrial activities, fish products contribute the greatest proportion of exposure to pollutants. In this study, risks and potential effects of dioxins to health of coastal populations in the Pearl River Delta were assessed. Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) were measured in common fish species purchased at local markets. Concentrations of total dioxins in fish ranged from 0.481 to 9.05 pg TEQ/g wet weight were similar to the lesser concentrations reported for fish from other countries. The greatest concentrations of dioxins were measured in mandarin fish, a carnivorous freshwater fish. Exposure of murine primary leydig and ovarian cells to 2,3,7,8-tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) reduced the synthesis of progesterone, testosterone and/or estrogen. The reductions were probably via inhibitory effects on the expression of the steroidogenic enzymes, steroidogenic acute regulatory protein (StAR) and cytochrome P450 side-chain cleavage enzyme (P450scc). Based on these reproductive parameters, the concentrations of dioxins and dioxin-like residues represent a moderate health risk due to consumption of fish.  相似文献   

黄河流域未来气候-水文变化的模拟研究   总被引：3，自引：0，他引：3  

康丽莉  LEUNG L Ruby  柳春  王守荣 《气象学报》2015,73(2):382-393

将大尺度半分布式水文模型VIC应用到黄河上中游流域(花园口水文断面以上),并利用区域气候模式RegCM4.0单向嵌套全球气候模式BCC_CSM1.1,动力降尺度到黄河流域的模拟结果驱动VIC模型,开展在新的典型浓度路径下(RCP4.5和RCP8.5)黄河流域未来气候和水文变化的离线模拟。模拟结果显示,在RCP4.5和RCP8.5排放情景下,黄河流域21世纪平均地表气温相对于1971—2000年均呈显著上升趋势,2019—2048年上升1.2—1.5℃,2069—2098年上升2.19—3.9℃。未来年平均降水量有微弱的增大,2019—2048年增幅为6%左右,2069—2098年增幅为1.4%—5.6%。未来蒸发量增大明显,2069—2098年年平均蒸发量最大可增加9.6%。2019—2048年花园口水文站的年平均径流量增大3.4%—7.4%,2069—2098年年平均径流量转为减少,减幅为3.3%—5.3%。黄河上游地区未来气候和水文变化趋势与黄河流域基本一致,但未来年径流量变幅低于黄河流域,相对比较稳定。  相似文献   

Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers     

Zhang AQ  Leung KM  Kwok KW  Bao VW  Lam MH 《Marine pollution bulletin》2008,57(6-12):575-586

Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 microug L(-1) Irgarol vs. > 200 microg L(-1) M1; S. costatum, 0.29 microg L(-1) Irgarol vs. 11.32 microg L(-1)M1; and T. pseudonana, 0.41 microg L(-1) Irgarol vs. 16.50 microg L(-1)M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.  相似文献   

Seasonal changes in imposex and tissue burden of butyltin compounds in Thais clavigera populations along the coastal area of Mirs Bay, China     

Ka Ming Chan  Kenneth Mei Yee Leung  Kwai Chung Cheung  Ming Hung Wong  Jian-Wen Qiu   《Marine pollution bulletin》2008,57(6-12):645

We assessed the current status of tributyltin (TBT) contamination of Thais clavigera (Gastropoda) along the coastal area of Mirs Bay, China for the first time. The snail samples were collected from 10 different sites in the summer (June) and winter (December) of 2006, respectively. They were analyzed for imposex status, i.e. relative penis size index (RPSI) and vas deferens sequence index (VDSI), followed by quantification of butyltins in their tissues. Most of the collected females suffered from imposex, but the level of butyltin contamination varied with the distance from Yantian Port, which is currently the fourth busiest container port in the world. The tissue concentration of TBT varied with season. For a particular site, the winter samples in general contained much higher concentration of TBT than the summer samples. RPSI, VDSI and organotin concentrations were higher in T. clavigera collected from sites closer to the Port, such as the Seafood Street and Kat O. Both RPSI and VDSI were positively correlated with the tissue burden of tributyltin. VDSI exhibited little seasonal variability, whereas RPSI showed marked seasonal variability, with lower values in the summer samples. The current results will serve as an important reference for long-term monitoring of butyltin contamination in this area.  相似文献   

近年中国夏季降水变化特征分析   总被引：1，自引：0，他引：1       下载免费PDF全文

赵宗慈  Leung Ruby  钱云 《气候变化研究进展》2005,1(1):29-31

利用台站观测资料和卫星观测换算资料,分析了近年（2002-2004年）中国夏季日内降水量变化统计学特征,其结果是较为一致的。对于东部大部分地区,日内最强降水易出现在下午到傍晚,对于西部大部分地区易出现在夜晚到清晨。夏季降水以对流降水为主,降水大的地区对应潜热通量也大。由于受观测资料的限制,计算结果有待更多的观测资料来验证。  相似文献   

UBV observations of short-period close binary V392 Orionis     

Xue-Fu Liu  Hui-Song Tan  Kam-Ching Leung 《Astrophysics and Space Science》1988,141(1):21-25

The eclipsing binary V392 Ori was observed photoelectrically, from November 1984 to January 1985, inUBV bands using the P34B photometer attached to the 0.91 m reflector at the McDonald Observatory. Four-hundred eighty-six observations in each band were obtained. Six primary and 4 secondary minimum were observed during this period. The light curves show a typical Beta Lyrae-type variation instead of an Algol-type light curve reported earlier.  相似文献   

Correction to: Urbanization Impact on Regional Climate and Extreme Weather: Current Understanding,Uncertainties, and Future Research Directions     

Yun QIAN  TC CHAKRABORTY  Jianfeng LI  Dan LI  Cenlin HE  Chandan SARANGI  Fei CHEN  Xuchao YANG  L. Ruby LEUNG 《大气科学进展》2023,40(2):333-333

  相似文献   

《坤輿万国全图》与《利玛窦中国札记》中外译本考疑   总被引：1，自引：0，他引：1  

李兆良 《测绘科学》2017,42(5)

金尼阁编译的《利玛窦中国札记》多种欧洲文字版本之间存在翻译差异,而300年后出版的英译本和中译本与原文存在严重错漏。600页的札记,利玛窦只用不到两页的篇幅叙述测绘《坤輿万国全图》一事,连实际比例尺的描述也不清楚。利玛窦承认没有见过其他的版本,"六幅版"地图出现在南京或北京,个别欧洲文字翻译版本不一,《坤輿万国全图》究竟是在南京还是北京完成的也有疑问。《利玛窦中国札记》用的是中国传统的测绘术语,指出地图的错误是针对西方地图而不是中国地图。《坤輿万国全图》中一半的中文地名,当时欧洲地图没有对应。1593年,利玛窦尚未制作《坤輿万国全图》,"六幅版"中文世界地图已出现在南京。因此,《坤輿万国全图》原本早已存在,《坤輿万国全图》应是郑和时代(1405—1433)大航海的成果,中国的地图学,不是西学东渐,甚至有可能是中国的世界地理与地图学流传到西方。世界地图史应该还原中国对地理大发现与地图学的贡献。  相似文献   

Vibration isolation by trenches in continuously nonhomogeneous soil by the BEM     

K. L. Leung  I. G. Vardoulakis 《Soil Dynamics and Earthquake Engineering》1991,10(3)

Vibration isolation of structures from ground-transmitted waves by open trenches in isotropic, linearly elastic or viscoelastic soil with a shear modulus varying continuously with depth is numerically studied. Both an exponential and a linear shear modulus variation with depth are used in this work. Waves produced by the harmonic motion of a rigid surface machine foundation are considered. The problem is solved by the frequency domain boundary element method employing the Green's function of Kausel-Peek-Hull for a thin layered half-space. Thus only the trench perimeter and the soil-foundation interface need essentially to be discretized. The proposed methodology is first tested for accuracy by solving two Rayleigh wave propagation problems in nonhomogeneous soil with known analytical solutions and/or for which experimental results are available. Then the method is applied to vibration isolation problems and the effect of the inhomogeneity on the wave screening effectiveness of trenches is studied.  相似文献