2021年6月16日茫崖MS5.8地震前地震条带特征研究

1 研究背景 地震活动条带图像是地震预测中常用方法之一.20世纪80年代,我国地震学家开始对地震条带进行清理和系统研究,如:陈章立等(1981)和陆远忠等(1985)对中国11次MS≥7.0地震和部分6.0—6.9级地震前区域地震活动图像进行研究,认为MS≥7.0地震前小震活动"条带"的出现具有一定普遍性,可将震前条带...     

Experimental study on the hydrological performance of green roofs in the application of novel biochar

Biochar has the potential to be a soil amendment in green roofs owing to its water retention, nutrient supply, and carbon sequestration application. The combined effects of biochar and vegetated soil on hydraulic performance (e.g., saturated hydraulic conductivity, retention and detention, and runoff delay) are the crucial factor for the application of the novel biochar in green roofs. Recent studies investigated soil water potential (i.e., suction) either on vegetated soil or on biochar-amended soil but rarely focused on their integrated application. With the purpose of investigating the hydraulic performance of green roofs in the application of biochar, the combined effect of biochar and vegetated soil on hydrological processes was explored. Artificial rainfall experiments were conducted on the four types of experimental soil columns, including natural soil, biochar-amended soil, vegetated natural soil, and vegetated biochar-amended soil. The surface ponding, bottom drainage and the volumetric water content were measured during the rainfall test. Simulation method by using HYDRUS-1D was adopted for estimating hydraulic parameters and developing modelling analysis. The results indicated that the saturated hydraulic conductivity of vegetated soil columns were higher than bare soil columns. The addition of biochar decreased the saturated hydraulic conductivity, and the magnitude of decrease was much significant in the case of vegetated soil. The influence of vegetation on permeability is more prominent than biochar. The vegetated biochar-amended soil has the highest retention and detention capacity, and shows a preferable runoff delay effect under heavy rain among the four soil columns. The results from the present study help to understand the hydrological processes in the green roof in the application of biochar, and imply that biochar can be an alternative soil amendment to improve the hydraulic performance.     

闽西北5月雨量特多年份环流特征及其成因分析

利用闽西北三明市的11个县、市1961—2014年5月降雨量资料、常规气象观测资料和NCEP 2.5×2.5°再分析资料等对闽西北历史上5月雨量特多年的降雨量时空分布特征和大气环流特征及其成因进行了分析,结果表明:5月区域性、全区性雨量特多年的环流异常特征是500hPa欧亚中高纬度自西向东环流呈"+-+"的波列分布,鄂霍次克海北侧高度正距平区的稳定少动,起到阻挡冷空气东移的作用,冷空气沿乌拉尔山西侧高度正距平中心前的偏北气流不断南下,使萨彦岭一带高度负距平中心加强,其底部不断分裂小槽东移影响闽西北。925hPa华南北部维持一条稳定切变线;对于2014年5月特例的环流形势分析结果可知,500hPa东亚大槽明显偏东,引导冷空气南下与强大副高西北侧西南暖湿气流交绥在闽西北上空。925hPa闽西北处于气旋式辐合区内。北支槽、南支槽均非常活跃,东移影响闽西北,是导致该地5月区域性降雨量特多的主要原因。     

改进的距离约束最小二乘模糊度搜索算法

针对短基线最小二乘模糊度搜索算法搜索效率低的缺点,该文提出了一种改善模糊度搜索空间以提高模糊度搜索效率的方法。最小二乘搜索算法通过基线长度范围确定模糊度搜索空间,完成模糊度的搜索和确认。距离约束的短基线模糊度搜索空间是一个空心椭球,各模糊度之间具有相关性,影响模糊度搜索效率。该文通过最小二乘去相关调整方法降低模糊度之间的相关性,减少搜索次数。实验证明,该算法的搜索效率提高了25%以上,且随着基线长度的增加,搜索效率有更多的提升。     

Study on Strength Influence Mechanism of Fiber-Reinforced Expansive Soil Using Jute

This study was undertaken to research the effects of jute fiber content, fiber length, water content and dry density of reinforced and unreinforced soil on the strength influence mechanism by implementing a series of laboratory tests and analysis. The most efficient fiber reinforcement effects was achieved by means of adding jute fiber with content of 0.6 % and length of 6 mm into expansive soil specimen prepared at maximum dry density and optimum moisture content. The cohesion of reinforced specimens increased first with increasing fiber content and fiber length and then decreased with further increase in fiber content and fiber length. The internal friction angle of reinforced specimens were not affected significantly by fiber content and fiber length. Higher water content reduces the fiber reinforcement effects by means of acting as lubricant in the interface of fiber and soil particles. Fiber reinforcement effects is more prominent for specimens prepared at higher dry density by increasing the effective contact area of fiber/soil. The application prospect of soil reinforcement using natural fiber is impeded by the hydrophilic nature and biodegradability of natural fiber, thus, studies on using chemical additive to do surface treatment for natural fiber are needed to improve the interfacial interaction of fiber/soil so as to widen the application of natural fiber.     

Fluid Inclusion and Stable Isotope Geochemistry of the Shangxu Gold Deposit, Northern Tibet

正Objective The Shangxu gold deposit is located in the south of the middle Bangong-Nujiang suture zone in northern Tibet.The origin of this deposit as an orogenic gold deposit is debatable.The study of the Shangxu deposit has a profound implication on gold exploration in the BangongNujiang metallogenic belt and can also improve our understanding of gold mineralization in northern Tibet.     

东北大三江盆地群早白垩世存在统一湖盆的沉积学证据

大三江盆地群位于黑龙江省东部,中生代以来经历了多期构造运动,形成现今各自分割的10余个残余盆地。由于缺乏关键性证据,前人对大三江地区早白垩世是否存在统一湖盆存在争议。本次研究通过野外地质调查和钻井岩心观察,认为盆地总体缺乏边缘相沉积,并且主要以三角洲平原亚相和滨浅湖亚相为主。古水流恢复和重矿物特征显示,研究区主要存在西部和西北部、东部以及东南部三大物源体系,并且平面上具有由四周向中心汇聚的特征。地震资料反射特征显示下白垩统具有典型的断陷-坳陷复合结构,坳陷时期地层由各盆地中心至边部未出现明显的地层减薄现象,现今的盆地边界断裂多为后期对盆地进行改造、破坏的逆冲断裂。这些证据都是对大三江地区早白垩世存在统一湖盆的有力支撑。本研究不仅能为大三江盆地群原型盆地的恢复提供重要依据,也将为东北盆地群油气资源远景评价和进一步的勘探部署提供参考。     

宁波沿海陆源排污口放线菌(Actinomycetales sp.)的分布特点

利用454高通量测序技术对宁波沿海10个陆源排污口20个站位的放线菌的时空分布及5个工业排污口的放线菌的种类作了整体分析。成功鉴定出了83个属,84个种。研究结果显示:放线菌在陆源排污口的分布呈现季节性分布,从3月份到10月份,放线菌数量呈现先升高后下降的变化,5月份和8月份数量居高,在3月份和10月份偏低;在综合排污口(S4,S6,S8和S9)检测频次较高,在工业排污口(S1,S3,S5,S7和S10)检测频次居中,在市政排污口(S2)检出频次最低。不同类型的排污口,氨氮浓度的排出量不同,放线菌的种类和数量也不同。在5个工业排污口中,S7和S10检出的共同菌最多;在S7独自检出短双歧杆菌(Bifidobacterium breve)、长双歧杆菌(B.longum)和两岐双岐杆菌(B.bifidum),表明存在粪源污染物;在S5检出皱孢链霉菌(Streptomyces scabrisporus)和硫藤黄链霉菌(S.thioluteus),显示有石油降解物和重金属的污染。总体上看,放线菌数量在距排污口外50m处略高于排污口处。排放指标越相似,菌的种类越接近。     

CO2加富对塔玛亚历山大藻叶绿素荧光参数及产毒的影响

由大气中CO_2浓度升高引起的海洋酸化,是全球性的重大环境问题之一。本研究采用实验生态学的方法,以塔玛亚历山大藻(Alexandrium tamarense)为研究对象,分析其在CO_2加富条件下叶绿素荧光动力学参数及产毒特征的变化。调制叶绿素荧光结果显示,CO_2加富对塔玛亚历山大藻的PSⅡ最大光化学量子产量(Fv/Fm)、最大相对电子传递效率(r ETRmax)有显著影响(P0.05),且随着培养时间的增长Fv/Fm、r ETRmax均降低,对半饱和光强(Ik)、快速光曲线初始斜率(α)却无显著影响(P0.05)。结果说明CO_2加富能促进塔玛亚历山大藻的PSⅡ最大光化学量子产量,提高其最大光能转换效率和相对最大电子传递效率。高效液相色谱法分析结果显示,该株塔玛亚历山大藻主要产漆沟藻毒素1(GTX1)、漆沟藻毒素4(GTX4)、N-磺酰氨甲酰基毒素(C1)及N-磺酰氨甲酰基毒素(C2)四种PSTs毒素,CO_2加富不改变主要麻痹性贝毒(PSTs)的种类组成,但能显著提高氨基甲酸酯类毒素(GTX1、GTX4)产量(P0.05),而降低N-磺酰氨甲酰基类毒素(C1、C2)产量(P0.05),说明加富能使塔玛亚历山大藻所产毒素发生转化,进而影响藻细胞的整体毒性。