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22.
疏浚物中镉释放的影响条件 总被引:4,自引:0,他引:4
本文模拟研究了疏浚沉积物中Cd的释放行为和影响条件。结果表明介质的盐度、pH、氧化还原状态等环境条件和疏浚沉积物的污染程度、粒度大小、有机质含量等理化特征对Cd的 释放有明显的影响。Cd从疏浚物中释放,其释放速率较快,释放率在40%~96%之间。疏物的海上倾弃可能引起Cd的污染和对部分生态环境的危害。同时还讨论了Cd的释放所遵循的动力学规律。 相似文献
23.
Convection in a Boussinesq fluid in an annular channel rotating about a vertical axis with lateral rigid sidewalls, stress-free top and bottom, uniformly heated from below is investigated. The sidewalls are assumed to be either perfectly insulating or conducting. Three different types of convection are identified when the channel is rotating sufficiently fast: (i) global oscillatory convection preferred for small Prandtl numbers in channels with intermediate or large aspect ratios (width to height ratio), (ii) wall-localized oscillatory convection representing the most unstable mode for moderate or large Prandtl numbers in channels with intermediate or large aspect ratios and (iii) global stationary convection preferred in channels with sufficiently small aspect ratios regardless of the size of the Prandtl number. The corresponding weakly nonlinear problem describing differential rotation and meridional circulation is also examined, showing that geostrophic, multiple-peaked (two prograde and two retrograde) differential rotation can be maintained by the Reynolds stresses in wall-localized convective eddies in a rapidly rotating channel. 相似文献
24.
A total of 144 free-field ground motions with closest site-to-rupture distances (Rrup) less than 200 km recorded during the 2010 Mw 7.2 El Mayor–Cucapah earthquake are used to investigate predictive capabilities of the next generation attenuation (NGA) ground-motion prediction equations (GMPE). The NGA GMPEs underpredict observed spectral accelerations at sites with shear wave velocity in the upper 30 m of the site (Vs30) between 180 and 366 m/s with Rrup from about 10 to 50 km and overpredict at sites with Rrup from about 50 to 200 km. Intra-event residuals of the NGA GMPEs exhibit a noticeable negative trend for peak ground acceleration and 0.3, 1.0, and 2.0 s periods. Comparison of the inter-event residual between the 2010 Mw 7.2 El Mayor–Cucapah earthquake and the NGA dataset reveals that short-period inter-event residuals from the 2010 Mw 7.2 El Mayor–Cucapah earthquake is within the scatter of inter-event residuals from the NGA dataset but long-period inter-event residuals do not appear within of the scatter of inter-event residuals from the NGA dataset. Spectral accelerations predicted by the NGA GMPEs are generally unbiased against Vs30 and periods of less than 4.0 s. Observed spectral accelerations show a stronger Vs30 dependence for both short and long periods compared with the NGA GMPEs. The Boore and Atkinson (Earthq Spectra 24(1):99–138, 2008) and Chiou and Youngs (Earthq Spectra 24(1):173–215, 2008) GMPEs perform better in predicting observed short-period spectral accelerations at the sites with Vs30 between 180 and 250 m/s than the Abrahamson and Silva (Earthq Spectra 24(1):67–97, 2008) and Campbell and Bozorgnia (Earthq Spectra 24(1):139–171, 2008) GMPEs. 相似文献
25.
The above article published online on 16 June 2011 in Wiley Online Library ( http://www.onlinelibrary.wiley.com ), and in Volume 39, pp. 697‐704, has been retracted by agreement between the Editor‐in‐Chief, Prisca Henheik, and Wiley‐VCH Verlag GmbH & Co. KgaA. The retraction has been agreed following an investigation carried out by Washington State University (WSU) which determined that research misconduct had occurred with respect to fabricating experimental data and falsifying data that formed the basis of a section of this article on the part of the corresponding author. Furthermore, WSU determined that the corresponding author did not declare an existing commercial conflict of interest when submitting the paper to the peer‐‐reviewed journal CLEAN ‐ Soil, Air, Water. 相似文献
26.
Zeng Jingjing Qu Jiansheng Pei Huijuan Dong Liping Liao Qin Liu Yanfei Zhang Zhiqiang 《地球科学进展》2015,30(11):1210-1217
The international climate change negotiation has been carried out over 20 years. The issue of climate change has shifted from a scientific question into a complex political matter which is related to the sustainable development of mankind. Based on the overview of major processes and stages of international climate conferences, this paper analyzed the key measures that major countries have taken to address climate change, as well as the primary tasks of Paris climate conference and recent international actions. The recent international climate policy issues were also analyzed in order to provide suggestions for China’s activel participation in the development of a new round of international climate change system. 相似文献
27.
帕米尔东北缘乌泊尔地区是正确认识帕米尔北缘盆山结构和构造变形特征非常关键的地区,本文利用连续电磁剖面(CEMP)资料和地震资料,并结合野外地质调查资料和钻井资料,对帕米尔东北缘乌泊尔地区的盆山结构和构造变形特征进行了研究。认为帕米尔东北缘及其以北地区的盆山结构表现为帕米尔造山带向北冲断和南天山向南冲断所形成的对冲结构; 帕米尔山前为基底卷入式构造,古生界—中生界沿高角度的逆冲断层推覆到新近系和第四系之上,形成山前的古生界—中生界逆冲推覆带; 北侧由受乌泊尔断裂控制的深部隐伏冲断体系和浅部的第四纪背驮盆地所构成。研究区的新生代构造变形时间开始于上新世晚期,并持续变形至今,形成了下更新统西域组(Q1x)与下伏上新统、Q2与Q1和Q3 4与Q2之间的不整合。研究区最小构造缩短量为486 km,缩短率为481%。 相似文献
28.
本文利用人工爆破地震资料,在频率域中,用波组频谱比方法计算了福州地区的Q结构,结果发现:该区中地壳低速层Q值明显偏低,仅为40——80,且存在横向变化,地壳上部和下部Q均为200左右;福州盆地与永泰——梧桐地段地壳平均Q也明显偏低,且福州盆地中部Q仅120—150,为全区最低值,低Q区与温泉分布和断裂位置有良好的对应关系。 相似文献
29.
The variation in the length of day has complicated time-varying characteristics and the traditional method for linear time series analysis is always difficult to obtain good effect of prediction. If the non-linear artificial neural network technique is adopted to predict the variation in the length of day, the topological structure of the network model is determined by the least square error method. By taking into account the close relation between the variation in the length of day and the general circulation of atmosphere, the axial sequence of atmospheric angular momentum is introduced into the forecasting model of neural network. The results show that the forecast accuracy is significantly improved by taking advantage of the combination of the length of day and the atmospheric angular momentum sequence in comparison with the individual adoption of the data of the length of day. 相似文献
30.
30ka以来南海东北部陆坡坡底沉积有机质的长链正构烷烃特征及其古植被意义 总被引:1,自引:0,他引:1
为探寻南海深海平原区的有机质组成特征、来源及其所反映的古气候/环境演化信息, 对南海东北部深水区的ZSQD289沉积柱状样品进行了正构烷烃组成及其单体稳定碳同位素的相关分析, 结合孢粉鉴定结果, 重点探讨该沉积区末次冰期以来陆源输入变化、源区的古植被演化及其气候响应因素。结果表明:30ka以来, 南海东北部深海陆坡坡底的沉积有机质以洋/陆混源为特征, 且以海洋自生生产力贡献为主, 其生源贡献存在明显的冰期/间冰期旋回变化特征, 冰期时陆源有机质输入明显高于全新世间冰期; 其陆源有机质应该主要由台湾南部河流输入, 在低海平面时通过海底峡谷搬运至此, 其过程中可能受到西太平洋底流和黑潮的影响。该沉积源区植被演化经历了C3/C4植物互为消长的变化过程, 但30ka以来主要还是以C3植物占优势, 由此推测末次冰期以来源区(台湾岛南部)不存在明显的干旱化, 冰期虽然温度较低但气候比较湿润。 相似文献