在SeisDps实时系统中用零点、极点计算ML的过程

在SeisDps地震处理软件的实时系统中,不是用系统的幅频特性计算震级ML,而是利用台站的零点、极点和增益,将记录的数字地震波形仿真成伍德-安德森地震仪记录的波形,计算具有3 大优点的ML震级,本文主要介绍用零点、极点和增益计算ML的过程。     

Paleogene marine deposition records of rifting and breakup of the South China Sea: An overview

A compilation of available marine deposition data from offshore S-SE China reveals evidence of rifting and breakup of the South China Sea (SCS) during the Paleogene. Marine deposition started earlier in the Paleocene in the East China Sea (ECS)-Taiwan region before expanding southwestward into the SCS region in the middle Eocene. Our data indicate the existence of an elongated Paleogene China Sea in these areas stretching along the northeasterly structural belts, probably as part of the marginal western paleo-Pacific. The southwestward shift of marine influence in the middle Eocene was responding to a period of intensive rifting and subsidence in the SCS region, while the sea in the ECS-Taiwan region started to shrink and shoal after the late Eocene, likely associated with local breakup and initial spreading in the Taiwan-Taixinan Basin area. The accumulation of hemipelagic sediments at ODP 1148 and IODP U1435 from near the continent-ocean boundary and at many other shelf-slope sites was in response to a large-scale breakup 34 to 33 Ma ago, subsequently leading to the birth of the SCS in the Oligocene.     

Effects of initial soil water content and saturated hydraulic conductivity variability on small watershed runoff simulation using LISEM

Abstract

Soil water content (θ) and saturated hydraulic conductivity (K_s) vary in space. The objective of this study was to examine the effects of initial soil water content (θ_i) and K_s variability on runoff simulations using the LImburg Soil Erosion Model (LISEM) in a small watershed in the Chinese Loess Plateau, based on model parameters derived from intensive measurements. The results showed that the total discharge (TD) and peak discharge (PD) were underestimated when the variability of θ_i and K_s was partially considered or completely ignored compared with those when the variability was fully considered. Time to peak (TP) was less affected by the spatial variability compared to TD and PD. Except for TP in some cases, significant differences were found in all hydrological variables (TD, PD and TP) between the cases in which spatial variability of θ_i or K_s was fully considered and those in which spatial variability was partially considered or completely ignored. Furthermore, runoff simulations were affected more strongly by K_s variability than by θ_i variability. The degree of spatial variability influences on runoff simulations was related to the rainfall pattern and θ_i. Greater rainfall depth and instantaneous rainfall intensity corresponded to a smaller influence of the spatial variability. Stronger effects of the θ_i variability on runoff simulation were found in wetter soils, while stronger effects of the K_s variability were found in drier soils. For accurate runoff simulation, the θ_i variability can be completely ignored in cases of a 1-h duration storm with a return period greater than 10 years, while K_s variability should be fully considered even in the case of a 1-h duration storm with a return period of 20 years.

Editor D. Koutsoyiannis; Associate editor A. Fiori     

Regulating Environmental Factors of Nutrients Release from Wheat Straw Biochar for Sustainable Agriculture

One mechanism by which biochar application enhances soil nutrient availability is through direct nutrients release from biochar. However, factors controlling the release processes are poorly understood. In this study, the effects of pH, biochar to water ratio, temperature, ionic strength, and equilibration time on the release of PO, NO, NH, K⁺, Na⁺, Ca²⁺, and Mg²⁺ from biochar were evaluated in simulated experiments. The release of PO, K⁺, Ca²⁺, and Mg²⁺ was significantly affected by extraction pH, suggesting that their release from biochar was pH dependent or an H⁺‐consuming process. Correlation analysis indicated that PO and Ca²⁺, PO and Mg²⁺, and Ca²⁺ and Mg²⁺ were co‐solubilized with increasing soil acidity. To a lesser extent, the recovery of the nutrients was also affected by the ratio of biochar to water: more nutrients were soluble with more water supply. In contrast, the release of Na was not affected by pH while the concentration increased with decreasing biochar to water ratio. Meanwhile, other factors (temperature, ionic strength, and equilibration time) had less effect on nutrient release from biochar. Under the influence of pH, the patterns of NO and PO release from biochar were different: extractable NO concentration was not affected by the pH but more PO was released in strongly acidic conditions. Our data suggested that P was mainly retained in inorganic forms while N was in organic forms in biochar. We conclude that environmental factors have marked influences on nutrients release from biochar.     

Heavy Metal Pollution in Sediments from Aquatic Ecosystems in China

We conducted an analysis of heavy metals content, including As, Cd, Cr, Cu, Hg, Pb, and Zn in sediments from aquatic ecosystems in China measured in recent publications. Then, we evaluated the extent of heavy metal pollution in these ecosystems in seven different industrial districts in China (Dongbei, Huabei, Huazhong, Huanan, Huaxik, Xibei, and Huadong) with the potential ecological risk index. We found that Cd was the most concentrated pollutant, followed by Hg and As, while Cr, Cu, Pb, Zn were found in low concentrations in sediments from all types of aquatic ecosystem in China. Sediments collected from all seven industrial districts were heavily polluted, and the sequence, from most to least polluted was Dongbei>Huabei>Huazhong>Huanan>Huaxi>Xibei>Huadong. All four types of aquatic ecosystem were found to be seriously polluted and the sequence, from most to least polluted was: river>sea>lake>wetland. Specifically, Cd and Hg were the most serious pollutants in all four aquatic ecosystems, and As was also a serious pollutant in rivers. For the seven industrial districts studied the sea was the most polluted ecosystem in Dongbei, the river was the most polluted ecosystem in Huabei, Huanan, Huazhong, and the lake was the most polluted in Huadong, Huaxi, and Xibei.     

A numerical study of mechanical behavior of a cement paste under mechanical loading and chemical leaching

Based on relevant experimental data of a petroleum cement paste under mechanical loading and chemical leaching, an elastic‐plastic model is first proposed by taking into account plastic shearing and pore collapse. The degradation of mechanical properties induced by the chemical leaching is characterized by a chemical damage variable which is defined as the increase of porosity. Both elastic and plastic properties of the cement paste are affected by the chemical damage. The proposed model is calibrated from and applied to describe mechanical responses in triaxial compression tests respectively on sound and fully leached samples. In the second part, a phenomenological chemical model is defined to establish the relationship between porosity change and calcium dissolution process. The dissolution kinetics is governed by a diffusion law taking into account the variation of diffusion coefficient with calcium concentration. The chemical model is coupled with the mechanical model, and both are applied to describe mechanical response of cement paste samples subjected to progressive chemical leaching and compressive stresses. Comparisons between experimental data and numerical results are presented.     

土壤氡方法用于断层活动性研究的讨论

本文系统地分析了海河断裂、天津南断裂、天津北断裂和沧东断裂等的土壤氡测量资料,用M-M珚值的组合以及H值、An值等3种方式对天津地区4条断裂的活动性强弱进行了分析和划分,经与活断层探测中得到的4条断裂的活动性分段结果对比发现,两者具有一定的一致性。同时发现,每种方法都有其局限性,进而认为,选择合适的方法,运用土壤氡测量资料能够对断层的活动性进行初步分析和分区,从而为断层的活动性分段提供参考。通过不同断裂间上述3组指标对比发现,土壤氡测量结果不能用于判断不同断裂间的活动性强弱。从实际工作出发,为利于分析断层的活动性分区,断层气测线在布设时应在探测断层与已知断裂的交汇部位附近适当增加密度。     

几种大型珍珠贝人工苗网箱式中间培育的研究

采用网箱式和传统式2种方法,在3个不同类型的海区(内湾性的陵水县黎安港、半开放性的雷州市流沙港、开放性的三亚市六道湾),进行几种大型珍珠贝人工苗的中间培育.经90d的中间培育后,结果表明:网箱式培育与传统式培育相比较,几种珍珠贝的生长速率和成活率都有较大幅度的提高.其壳高生长速率的增幅分别为:珠母贝18.9%、18.2%、19.9%;大珠母贝22.8%、20.6%、23.5%;企鹅珍珠贝21.8%、20.7%、21.7%;均为差异显著(P＜0.05)或差异极显著(P＜0.01).成活率的增幅分别为:珠母贝175.0%、147.9%、133.9%;大珠母贝172.8%、159.0%、127.4%;企鹅珍珠贝122.5%、118.2%、102.2%,均为差异显著(P＜0.05)或差异极显著(P＜ 0.01).     

华南晚二叠世层序—古地理及聚煤规律*

晚二叠世是地质历史中重要的成煤时期,在中国南方多个省区都形成了可采煤层。受海平面变化的影响,华南地区晚二叠世发育一套完整的陆相—海陆过渡相—海相含煤岩系。通过对野外露头及钻孔剖面资料分析,识别出了区域不整合面、下切谷底部冲刷面、河道间古土壤层和沉积相转换面等关键层序地层界面,以及依据海相石灰岩标志层横向分布规律反映的区域最大海泛面,同时结合前人关于华南地区地层对比及煤层对比方面的成果,将华南上二叠统划分为3个三级层序及9个体系域。利用单因素分析多因素综合作图法恢复了各层序中岩相古地理及煤层分布规律,结果表明:层序Ⅰ中煤层主要形成于潮控下三角洲平原以及潟湖潮坪环境,厚煤层的展布受这些沉积相带控制;层序Ⅱ中三角洲平原环境中煤层最厚,开阔台地煤层最薄,平面上煤层厚度表现为西部厚、中部次之、东部无煤的阶梯式递变;层序Ⅲ中煤层主要形成于三角洲平原环境,此时聚煤作用主要发生于华南西部的康滇古陆东侧,在华南中部及东部大部地区发育的浅海台地和深水盆地均不利于聚煤作用发生。     

Characteristics of the Two Types of Granits at Sikongshan in the Eastern Part of the Dabieshan Mountains

It has been shown from petrologic,geochemical,trace element and REE evidence that the gran-ite intrusions at Sikongshan,Anhui Province,can be assigned to two distinct types which are radically different in age and origin.The Precambrian gneissic granited resulted from remelting of old continental crust while the Mesozoic granites were derived ,also through remelting,from low-Rb/Sr rocks at greater depths.Granite masses at Tiantangzhai and Zhoujiawan in the Dabieshan Mountains are also dicussed.