Accumulation of butyltin compounds in finless porpoises (Neophocaena asiaeorientalis) from Korean coast: Tracking the effectiveness of TBT regulation over time     

Minkyu Choi  Yong-Rock An  Kyum Joon Park  In-Seok Lee  Dong-Woon Hwang  Jinyu Kim  Hyo-Bang Moon 《Marine pollution bulletin》2013,66(1-2):78-83

The concentrations of butyltin compounds (BTs) were measured in the livers of finless porpoises (Neophocaena asiaeorientalis) caught off the Korean coast in 2003 and 2010, to assess the effectiveness of legislative action against BTs. The concentrations of BTs ranged from 65.1 to 1432 (average: 370) ng/g wet weight, within the ranges reported by previous studies. The levels of BTs in almost all the samples exceeded the suggested threshold value, implying potential adverse health effects from the BT exposures. Concentrations of BTs were significantly correlated with body length, weight, and age of finless porpoises, but were not correlated with sex. Spatial differences in the concentrations of BTs were not observed between Yellow and South Seas, while there was a significant decrease in BTs between the sampling years of 2003 and 2010. Our result indicates that the effectiveness on TBT ban has reached to marine mammals in the coastal waters of Korea.  相似文献   

What is the topset of a shelf-margin prism?     

Ronald J. Steel  Cornel Olariu  Jinyu Zhang  Si Chen 《Basin Research》2020,32(2):263-278

The siliciclastic topset of a continental margin, or a shelf-margin prism in subsiding nonplate-margin deepwater basins, is the flat-lying upper part of the margin succession; it is coeval basinwards with deepwater slope clinoforms. Topsets develop by the aggradation of repeated, cross-shelf, shoreline regressions and transgressions, thereby hosting the shelf portion of stacked, fourth-order stratigraphic sequences. Sediment spreading downdip and along strike during the cross-shelf transit of the sediment delivery system, as well as process regime changes of deltas and shorefaces (regressive) and of estuaries, barrier–lagoon systems and shelf ridges (transgressive) are highly variable over short distances, so that correlation within a single stratigraphic sequence is far more difficult than correlation of the cross-shelf maximum flooding surface boundaries. Thickness of individual regressive–transgressive, fourth-order sequences is given by shelf accommodation, typically <10 m in embayment or on the inner shelf and up to 200 m on outer shelf. Tectonic subsidence and compaction will enhance this thickness only if rates are very high compared to shelf-transit time. In very high subsidence rate settings, the transgressive tracts are well preserved and often thickly developed. Topset sequences in an Icehouse climate setting tend to have a high proportion and greater landward development of marine vs nonmarine deposits, compared to Greenhouse sequences, because of the importance of eustatic rise of sea level in the former. Previous numerical experiments show that even for very wide shelves and irrespective of Icehouse or Greenhouse conditions, deltas rarely take more than 10 s of ky to reach their shelf edge, suggesting that it is fourth-order (or higher) sequences that are the fundamental ones in sequence stratigraphy.  相似文献   

轴向变形对拱自振频率影响的样条有限点法     

康婷  许金余  白应生  姚山 《地震工程与工程振动》2012,32(3):41-46

提出用样条有限点法计算拱的横向振动和纵向振动的最小频率。用3次B样条函数的线性组合模拟拱自振时的位移振型函数,根据Hamilton原理推导出了拱结构自由振动频率方程。通过实例验证了样条有限点法计算效率高、精度高、计算格式简单,较有限元法具有很大优越性。计算分析了轴向变形对横向振动最小频率的影响,提出了临界矢跨比的概念。考虑轴向变形时不仅频率系数的大小发生了变化,同时它的变化规律也与原来不同。当结构的矢跨比小于临界矢跨比时,横向振动最小频率较不计轴向变形时减小,随着矢跨比的增大逐渐增大;当结构的矢跨比大于临界矢跨比时,横向振动最小频率较不计轴向变形时增大,随着矢跨比的增大逐渐减小。由此给出了目前广泛使用的横向振动最小频率曲线的适用范围,同时建立了纵向振动频率计算用曲线。  相似文献   

Tidally averaged water and salt transport velocities and their distributions in the Pearl River Estuary     

Shouxian Zhu  Jinyu Sheng  Xiaomei Ji 《Ocean Dynamics》2016,66(9):1125-1142

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长期暴露于沙尘人群的肺通气功能     

王金玉  李盛  王式功  尚可政 《中国沙漠》2014,34(4):975-981

为分析长期沙尘暴露对人群肺通气功能的影响,本文选择沙尘天气多发的甘肃省民勤县和受沙尘污染较轻的平凉市为调查点,采用SPIROVIT SP-1型肺功能仪,对在调查点长期居住、无职业性粉尘接触史的40岁以上728名农民进行肺功能测定,测定指标包括用力肺活量（FVC）、第1秒用力呼气容积（FEV_l）、1秒率（FEV_l/FVC）,肺通气功能损伤类型分为阻塞性（FEV_l/FVC<70%）、限制性（FVC%<80%）及混合性（FEV_l/FVC<70%且FVC%<80%）3类。结果显示,与平凉市比较,非吸烟者中,民勤县农民FEV₁%、FEV₁/FVC分别降低4.3%、6.6%;肺通气功能异常、阻塞性及混合性肺功能损伤发生率分别增加9.5%、9.2%及3.2%,其RR（95%CI）分别为1.540（1.106~2.144）、1.955（1.242~3.076）及8.677（1.128~66.734）;50~59岁农民阻塞性肺功能损伤发生率、60岁以上者肺通气功能异常、阻塞性及混合性肺通气功能损伤发生率均增加;男性农民肺通气功能异常率、女性农民阻塞性及混合性肺功能损伤发生率均增加。这表明,长期沙尘暴露可导致人群肺功能降低,以阻塞性肺功能损伤为主,50岁以上人群是主要受害者。建议沙尘天气多发区人群应尽量减少沙尘暴露机会,并加强沙尘防护措施,以降低沙尘对暴露人群肺通气功能的损伤。  相似文献   

影响桂东南东风波特征及其概念模型   总被引：1，自引：0，他引：1  

林确略  彭武坚  刘金裕 《气象研究与应用》2010,31(1):5-10

利用NCEP 2.5°×2.5°风场每6h再分析资料和常规观测资料,分析了近40a(1970.7～2009.9)35次影响桂东南的东风波天气过程。通过降雨强度、雨区分布及系统结构的统计分析,对东风波进行了归类。基于典型东风波过程,运用合成分析方法建立了各类东风波天气概念模型,结合本地预报经验提出了桂东南东风波的预报着眼点。  相似文献   

青岛竹岔岛存在古火山口吗?     

孟元库  侯方辉  杨金玉 《地质论评》2017,63(6):63061585-63061586

<正>青岛竹岔岛位于黄海之中,距离最近的陆地约3km(图1a),主要由4个岛屿组成,总面积约0.38 km~2。竹岔岛上以发育有一"古火山口"而远近闻名(图1b),每年都吸引不少游客前来参观,成为了青岛市重要的科普教育基地。  相似文献   

Changes in local oceanographic and atmospheric conditions shortly after the 2004 Indian Ocean tsunami   总被引：1，自引：1，他引：0  

Zhongzhen Yan  Yi Sui  Jinyu Sheng  Danling Tang  I-I Lin 《Ocean Dynamics》2015,65(6):905-918

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Numerical study of seasonal circulation and variability over the inner shelf of the northern South China Sea     

Xiaomei Ji  Jinyu Sheng  Jinhai Zheng  Wei Zhang 《Ocean Dynamics》2015,65(8):1103-1120

This study examines seasonal circulation, hydrography, and associated spatial variability over the inner shelf of the northern South China Sea (NSCS) using a nested-grid coastal ocean circulation model. The model external forcing consists of tides, atmospheric forcing, and open boundary conditions based on the global ocean circulation and hydrography reanalysis produced by the Hybrid Coordinate Ocean model. Five numerical experiments are conducted with different combinations of external forcing functions to examine main physical processes affecting the seasonal circulation in the study region. Model results demonstrate that the monthly mean circulation in the study region features the Guangdong Coastal Current (GCC) over coastal waters and the South China Sea Warm Current (SCSWC) in the offshore deep waters. The GCC produced by the model flows nearly southwestward in winter months and northwestward in summer months, which agrees with previous studies. The SCSWC flows roughly northeastward and is well defined in summer months. In winter months, by comparison, the SCSWC is superseded by the southwestward strong wind-driven currents. Analysis of model results in five different experiments demonstrates that the monthly mean circulation over coastal and inner shelf waters of the NSCS can be approximated by barotropic currents forced by the southwestward monsoon winds in winter months. In summer months, by comparison, the monthly mean circulation in the study region is affected significantly by baroclinic dynamics associated with freshwater runoff from the Pearl River and advection of warm and saline waters carried by the SCSWC over the NSCS.  相似文献   

西昆仑造山带东段阿拉玛斯岩体Pb-Hf同位素组成特征、岩石成因及源区特征     

张其超  吴珍汉  李侃  黄河  刘琰  刘志伟  周清  金谋顺  倪晋宇 《地质学报》2017,91(12):2667-2678

后碰撞阶段花岗质岩浆的源区多较为复杂,需要从多方面开展同位素的研究来加以识别,阿拉玛斯花岗质岩体位于西昆仑造山带东段。先前的研究表明阿拉玛斯岩体是后碰撞阶段下地壳部分熔融。为进一步研究阿拉玛斯花岗岩类的源区特征,本文对阿拉玛斯花岗岩类进一步进行Pb-Hf同位素的测定。结果显示:阿拉玛斯岩体具低的锆石εHf(t)值为-9.5~-3.2(平均值为-5.6),二阶段模式年龄为1633~2028 Ma,反映了岩浆来源于较老的下地壳部分熔融。阿拉玛斯岩体的206Pb/204Pb范围为18.382~19.333,平均值为18.784,207Pb/204Pb范围为15.589~15.642,平均值为15.614,208Pb/204Pb范围为38.585~39.080,平均值为38.800,μ值范围为9.45~9.48,平均值为9.46,ω值的范围33.80~38.14,平均值为36.16。在岩体源区判别图解上,样品主要落在上地壳的范围内,反映了阿拉玛斯岩体源区具有高Pb的同位素特征,说明岩浆源区有少量高Pb物质(沉积物)的混入,从而说明后碰撞阶段形成岩体的物质来源具有多样性。  相似文献