基于CMB模型的巴丹吉林沙漠沙源区分析

沙漠因其高反照率、低比热容的下垫面以及粉尘高输出率的特征对全球和区域环境有重要的作用.作为具有高大沙山的第二大流动性沙漠,其物质来源一直是地球科学研究热点.通过对巴丹吉林沙漠及周边地区表层沉积物进行矿物分析,在此基础上对巴丹吉林沙漠的可能物源区进行分析,进一步利用化学质量平衡(CMB)模型探讨了各物源区对巴丹吉林沙漠的...     

锡在花岗质熔体和流体中的性质及分配行为研究进展

元素在流/熔体间的交换、分配过程是岩浆热液矿床形成的重要环节,作为与岩浆活动有密切成因联系的典型矿种之一,锡在花岗质熔体和流体中的存在形式、分配行为及其影响因素是认识其成矿机理的关键。锡在花岗质熔体和流体中的分配特征不仅受温度、压力、氧逸度等条件的制约,流体组成和熔体的NBO/T（非桥氧键/桥氧键）、碱含量、AlK/Al(总碱与铝含量比)也是制约锡分配行为的重要因素;挥发分F、Cl对锡在流体、熔体中的地球化学行为影响尤为明显。     

不正规半日潮海区高(低)潮选取的探讨

高(低)潮是潮汐观测的重要要素,在防灾减灾中起到重要的作用.由于不正规半日潮海区在1个朔望月期间,当月赤纬较大时的1个太阴日内,第2次高潮很小,半日潮特征不显著,潮差较小,导致目前在不正规半日潮海区潮差较小时如何挑取高低潮存在不同观点.本文对不正规半日潮海区高低潮的选取,从理论和实测资料方面做了讨论,提出在不正规半日潮...     

黄海苏北浅滩海域春夏季浮游植物时空分布及其控制生态因子

The Subei Shoal is a special coastal area with complex physical oceanographic properties in the Yellow Sea. In the present study, the distribution of phytoplankton and its correlation with environmental factors were studied during spring and summer of 2012 in the Subei Shoal of the Yellow Sea. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. Diatoms represented the greatest cellular abundance during the study period. In spring, the phytoplankton cell abundance ranged from 1.59×10~3 to 269.78×10~3 cell/L with an average of 41.80×10~3 cell/L, and Skeletonema sp. and Paralia sulcata was the most dominant species. In summer, the average phytoplankton cell abundance was 72.59×10~3 cell/L with the range of 1.78×10~3 to 574.96×10~3 cell/L, and the main dominant species was Pseudo-nitzschia pungens, Skeletonema sp., Dactyliosolen fragilissima and Chaetoceros curvisetus. The results of a redundancy analysis(RDA) showed that turbidity,temperature, salinity, pH, dissolved oxygen(DO), the ratio of dissolved inorganic nitrogen to silicate and SiO_4-Si(DIN/SiO_4-Si) were the most important environmental factors controlling phytoplankton assemblages in spring or summer in the Subei Shoal of the Yellow Sea.     

Experimental Study on the Hydrodynamic Characteristics of a Submersible Fish Cage at Various Depths in Waves

Submersible fish cages can be submerged under the water to mitigate the negative effects that arise from severe sea conditions and improve the growing environment for the farmed fish. Thus they are increasingly applied in offshore aquaculture. To ensure both safety and economic efficiency of submersible fish cages, it is important to determine the optimum submergence depth. In this study, a series of physical model experiments were conducted to investigate the hydrodynamic performance of a submersible fish cage at various submergence depths(1/6, 1/4, 1/3, and 1/2 of the water depth as well as the floating condition for reference) with a model scale of 1:20. The results of the physical model experiment for the different depths were compared to analyze the effects of submergence depths on the mooring line tension and the movement of the floating collar. The results showed that the mooring line tension and the floating collar movement significantly attenuated with increasing submergence depth. However, the attenuation tendency became stable when the fish cage reached a certain depth. According to the results, 1/3 of water depth was determined as the optimal submergence depth of the fish cages. Deeper submergence depths showed no significant advantage from a perspective of the hydrodynamic characteristics of the fish cage. The determination of the optimum submergence depth is beneficial for the structural design and operation safety of submersible net cages.     

Numerical investigation of effects of “baffles-deceleration strip” hybrid system on rock avalanches

Arrays of baffles are usually installed in front of protection site to attenuate the flow energy of rock avalanches in mountainous areas. Optimization design is crucial for efficiency promotion in hazard energy dissipation engineering. In this study, a deceleration strip was added in the baffles protection system to optimize the traditional baffles system. The effects of the "baffles-deceleration strip" hybrid protection system was discussed in detail with the nails number and nails angle. This study presents details of numerical experiments using the discreteelement method(DEM). The effect of the optimization of hybrid protection system(nail angle and nail number) were investigated specifically, especially the impact force that avalanches exerted on structures. The results show that the maximum impact forces and kinetic energy of the rock avalanches decreases with the increase of the number and angle of the nail. Moreover, the distance between the toe and the bearing structure(L_m) is also a key factor. The shorter the distance L_m(30 m) is, the higher the maximum impact force are. The longer the distance L_m(70 m) is, the lower the maximum impact force are. Under the same size of the nails, increasing the numbers can enhance the dissipation ability of the hybrid protection system. Meanwhile, increasing itsangle can also enhance the dissipation ability. There are three key ways for nails attenuate rock avalanches:(i) block the fine particles directly;(ii) form the particles bridge between nails and baffles;(iii) dissipate the coarse particles energy directly. The effect of segregation in rock avalanches is crucial for the energy dissipation mechanism, which is a key factor to optimize the traditional baffle system.     

贫金属富碳天琴RR变星的形成

贫金属富碳恒星(Carbon-Enhanced Metal-Poor, CEMP)是研究宇宙早期恒星性质和化学演化的极佳样本,通常认为来自双星.目前发现的贫金属富碳星中有9颗天琴RR变星(RR Lyrae star, RRL),其中至少7颗未表现出任何双星特征.传统双星物质转移模型不足以充分解释贫金属富碳天琴RR变星(CEMP-RR Lyrae)单星的形成.之前研究表明氦白矮星和赫氏空隙星(HG)的并合模型可以解释部分富碳红巨星单星的碳增丰现象,因此贫金属富碳星单星也可能来自氦白矮星和赫氏空隙星的并合模型渠道.通过详细计算的氦白矮星和赫氏空隙星并合模型来检验这一演化渠道,结果表明:该并合模型在后续的演化过程中,其重力加速度、温度、表面碳丰度均能与观测符合较好.由此,氦白矮星和赫氏空隙星并合模型极有可能是贫金属富碳天琴RR变星的形成渠道之一.     

利用卫星微波观测亮温与云辐射模拟亮温的台风定位分析

极轨气象卫星S-NPP、MetOp-A和FY-3B上搭载的微波湿度计观测资料可以反映出台风周围水汽和云雨结构。本文使用权重函数峰值在800 hPa附近的微波湿度计通道观测资料和ERA5再分析资料全天空模拟亮温,以飓风Sandy和Isaac为例,对用方位谱台风中心位置定位方法得到的观测和模拟中心位置进行了比较。利用下午星S-NPP搭载的先进技术微波探测仪(Advanced Technology Microwave Sounder, ATMS)和上午星MetOp-A搭载的微波湿度计(Microwave Humidity Sounder, MHS)观测亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差35.8 km(32.9 km),但用ERA5全天空模拟亮温得到的飓风Sandy(Isaac)中心位置与最佳路径平均相差73.3 km(82.1 km)。若按照热带风暴和台风等级来划分,ATMS和MHS观测和模拟亮温得到的台风中心位置与最佳路径的平均距离对热带风暴分别是36.5 km和105.9 km,对台风分别是25.8 km和56.4 km。若用FY-3B搭载的微波湿度计(以M...     

岩背花岗岩黑云母矿物化学研究及其对成矿意义的指示

对岩背火山-斑岩型锡矿含黄玉黑云母花岗岩和含黄玉花岗斑岩中黑云母矿物化学研究表明,含黄玉黑云母花岗岩中的黑云母属于富铁黑云母,含黄玉花岗斑岩中的黑云母属于铁叶云母。含黄玉花岗斑岩的成岩温度为720℃~730℃,logfO2为-15.5~-15.7;含黄玉黑云母花岗岩的成岩温度为510℃~550℃,logfO2为-19.2~-18.7。含黄玉花岗斑岩成岩温度、氧逸度高于含黄玉黑云母花岗岩成岩温度和氧逸度。与含黄玉花岗斑共存热液流体log(fH2O/fHCl)fluid值为4.29~4.99,与含黄玉黑云母花岗岩共存热液流体log(fH2O/fHCl)fluid值为3.15~3.67。因此,相对于含黄玉黑云母花岗岩,含黄玉花岗斑岩岩浆演化过程中分异出的流体富F和Sn,即岩背含黄玉花岗斑岩岩浆演化过程分异出的原始流体以富F和Sn为特征,结合有关岩背Sn矿成矿流体的研究结果,进一步揭示出岩背Sn矿成矿流体为岩背含黄玉花岗斑岩岩浆演化过程分异出的岩浆热液,相对于含黄玉黑云母花岗岩,含黄玉花岗斑岩与锡成矿关系更密切。     

莱州湾南岸平原地下水化学特征研究

用2009年莱州湾南岸地下水最新监测数据,将研究区地下水淡水区、微咸水区、咸盐水区和卤水区进行经典统计分析、相关分析、等值线图和Piper三线图绘制,阐述了水化学类型和成分特征从南往北的变化:EC、TDS、Na+、K+、Mg2+、Cl-、SO42-的平均浓度从南部淡水到北部卤水呈现逐渐增大趋势,因为在卤水区普遍发生碳酸钙沉淀,Ca2+和HCO3-则在咸盐水区浓度达最高;pH值从淡水到卤水呈现从弱碱性到弱酸性的转变;从淡水区向卤水区地下水化学组分阴离子由HCO3-为主变为Cl-为主,阳离子由Ca2+为主变为Na+为主;此外河流对地下水起到淡化和冲刷的作用。主成分分析法提取了水化学3个主成分,分别代表了地下水盐化指标、生物化学作用和碳酸钙沉淀。进一步结合系数比值法和饱和指数计算,在对本区水文、地质以及离子水文地球化学特性分析基础上,指出地下卤水阴阳离子中占绝对优势的Cl-、SO42-、Na+、Mg2+的毫克当量百分数与正常海水的值非常相近而与地下淡水的值相差甚远,反映出本区地下卤水起源于古海水,为沉积海水。此外卤水绝非海水简单浓缩的产物,其间还包括复杂的水化学变质过程及后期演化如矿物沉淀、阳离子交换(K+-Ca2+;Na+-Ca2)+、去白云岩化作用和硅酸盐蚀变等。饱和指数的计算表明石膏在卤水矿化度达100 g/L之后才开始缓慢沉淀,而文石、方解石和白云石基本一直处于饱和沉淀状态,且文石和方解石的饱和指数散点分布极为相似,说明两者可能同时发生沉淀。