Should the Three Gorges Dam be blamed for the extremely low water levels in the middle–lower Yangtze River?

Extremely low water level events have frequently occurred in the middle–lower Yangtze River (MLYR) in recent years (2006–2011). Most of these drought events coincided with the initial operation of the Three Gorges Dam (TGD). The TGD was therefore the focus of controversy about the causes of the hydrological droughts of the rivers and lakes of the region. We quantified the effects of the TGD's operation on water levels from 2006 to 2011 using a newly developed hydrodynamic model. The operation of the TGD significantly exacerbated the severe hydrological droughts that occurred in late September to November because of water impoundment, but it increased water levels from April to early June in the MLYR because of the drawdown of TGD water levels. Evidence suggests that the recent extremely low water levels were mainly because of the remarkable decline in inflows to the MLYR resulting from precipitation changes and possible human activities. Nevertheless, it should be noted that the effects of the TGD on downstream rivers and lakes will be intensified in the foreseeable future. Copyright © 2013 John Wiley & Sons, Ltd.     

利用两类雷达探测资料分析超强台风“威马逊”登陆期间结构演变特征

利用实时多普勒天气雷达、边界层风廓线雷达和自动站资料对超强台风“威马逊”第4次登陆广西沿海时台风结构的演变特征进行研究,结果表明：台风眼区气压呈“漏斗”形变化,具有气压低、风速弱、空气干而暖的特征;登陆过程中眼区保持圆形,半径约为30 km,是典型强台风结构;天气雷达径向速度大风区具有非对称性,右象限大于左象限;风廓线雷达水平风场能够精确、直观地描述台风不同部位经过测站时的垂直结构特征,从低层到高层风向先后经历了“东北风—东风—东南风—南风”的转变过程,风速整体上呈现随高度先增大后减小的特点,其垂直速度和大气折射率结构常数(C2n)能够很好地反映台风的结构及其云和气流的变化特征;两种雷达风场产品的风向一致,但是VWP产品的风速比风廓线雷达的要小,VWP产品出现无效数据时,可以用风廓线雷达产品作为补充。     

新一代中国数字地震台网（NCDSN）台站系统

以白家疃数字地震台为例，介绍了新一代中国数字地震台网（ＮＣＤＳＮ）台站系统的各种硬件单元及它们的相互联系与特征。同时介绍了系统的频率响应、数据流和动态范围，并与中国数字地震台网（ＣＤｓＮ）—期设备进行了简单比较。     

陆相特殊沉积的研究方法及气候意义

陆相沉积形成于地圈与水圈、大气圈和生物圈的交界面上,比海相地层更有效地记录了地球表层环境的信息。通过对沉积岩中沉积物的粘土矿物、气候指数、氧同位素测温等研究,获得关于气候干湿冷暖的信息。基于对这些常用方法的研究,提取出一些陆地上的特殊沉积,如：陆相红层、沙漠沉积体系、蒸发岩、煤及油页岩等所包含的丰富气候信息。沙漠代表干旱炎热气候;陆相红层的出现反映高温氧化环境,其在干旱和潮湿的热带气候下都能形成;芒硝代表干冷的气候环境;石膏则代表干热,水体盐度高,蒸发作用强的气候条件;煤层/油页岩一般形成于温暖潮湿的气候环境。对特殊沉积的研究可以用来重建古气候和恢复大陆古环境。     

基于ECFLOW实现华中区域快速更新同化预报业务流程

为了进一步满足华中区域对高时空分辨率数值预报产品的业务需求,为短临预报和精细化格点预报提供技术支撑,华中区域快速更新同化预报模式系统于2015年7月完成系统搭建并开始业务试运行,2017年12月又根据业务需要完成了系统结构的调整。由于该系统具有流程复杂,步骤繁多的特点,为了使调度监控更加直观,故障定位更加准确,系统维护更加高效,运用ECFLOW技术对整个预报系统进行了流程化调度开发,设计并实现了华中区域快速更新同化预报业务流程监控系统。该系统图形界面美观友好,流程结构清晰明了,故障定位准确且处理操作简单,可大幅提升业务模式运行监控及维护的工作效率。     

Geology and Mineralogy of the Baolun Hydrothermal Gold Deposit in the Hainan Island, South China

Abstract. The Baolun quartz vein type Au deposit, is located at the southwestern Hainan Island. It occurs next to a Triassic ilmenite-series/S-type syenogranite complex. A ⁴⁰Ar/³⁹Ar plateau age for muscovite from the master orebody is dated to be 219.4±0.6 Ma, suggesting that the gold deposit genetically related to the granite pluton. In the Baolun mining area, orebodies of auriferous quartz vein and wall rock alteration occur in NNW-striking fracture zones hosted by weakly metamorphosed turbidite of the Lower Silurian age. Eight fracture zones, 400∼1300 m long and 10∼30 m wide, have been identified. The five fracture zones of them form orebodies. The ores are mainly of quartz vein type. More than 20 orebodies in shapes of vein and lens of 195∼751 m in length and 0.20∼7.49 m in thickness are known, and 14 of them occur in the No. 1 vein belt. Silicification, sericitization and pyritization are closely related to the Au mineralization. The ores exhibit commonly 1.54∼29.48 g/t in Au grade, partially >98 g/t. The master orebody is 720 m long and 2.62 m thick in average, with 9.53∼29.27 g/t Au. Gold reserves of more than 70 t have been proven by geological exploration. More than 20 metallic minerals including native gold and sulfides such as pyrite, pyrrhotite, chalcopyrite, and others are identified to be formed in four ore-forming stages: (1) Au-coarse grain quartz stage, (2) Au-fine grained quartz stage, (3) Au-bismuthide-bismuth sulfosalt-sulfide-quartz stage, and (4) calcite-sulfide-quartz stage. The Au mineralization in this deposit occurred mainly in the first three stages. A variety of Bi- and Te-bearing minerals is closely associated with native gold suggesting that the mineralization may take place in a relatively high temperature.     

鄂尔多斯盆地环西—彭阳地区长8段储层流体性质测井判别方法

鄂尔多斯盆地环西—彭阳地区长8段储层蕴含丰富油气资源，但储层非均质性强，孔隙结构复杂，且受异常低压、黏土矿物附加导电以及高束缚水饱和度影响，油水层分异差，测井响应特征差异不明显，流体性质识别难度大。本文通过岩芯薄片观察、常规测井等资料，对长8段储层四性关系等进行了研究，结果表明长8段岩性主要是中、细砂岩，平均孔隙度14. 68%，渗透率7. 13×10-3 μm2。在此基础上引入视地层水电阻率作为有效参数，建立RwaAC交会图版，该方法考虑了不同储层物性的差异对储层电性的影响，克服了储层孔隙结构复杂因素的影响，突出了含油气信息，能有效识别不同的流体类型，通过该方法实现了12口井70个层位流体性质测井判别，与试油资料验证良好。研究成果对于长8段储层测井评价和油气勘探开发具有指导意见。     

A COMPARISON OF EASTERN AND WESTERN HONG KONG PHYTOPLANKTON FROM WEEKLY SAMPLES （1997-1999）

Weekly phytoplankton samples were taken from western Hong Kong (Lamma) from Jan. 1997 to Dec. 1999 and from Port Shelter in Eastern Hong Kong from January 1998 to December 1999. During that time diatom blooms occurred repeatedly at both sites but never in synchrony. One species would bloom at one site and then weeks later it or another species would bloom at the other site; while the 1998 red tide of the mucus producing dinoflagellateGymnodinium mikimotoi occurred at both sites. It first occurred at the Port Shelter site in March and did not appear at the Lamma site until April. With the single exception of this species, no other dinoflagellate reached bloom concentrations at the Lamma site. In addition, dinoflagellate abundance at the Lamma site was significantly lower (P<0.05) than that at the Port Shelter site. This was correlated with a significantly higher turbidity (i. e. low Secchi transparency) and higher turbulence (stronger currents) at the Lamma site. Annual variation in surface temperature correlated with total surface phytoplankton abundance at both our sample sites. Phytoplankton abundance increased in spring as water temperatures warmed. In fall, as surface water temperatures began to decline and the monsoon rains became less frequent there was a reduction in phytoplankton abundance associated with the reduction in temperature and light. Because so many variables co-occur with temperature (e. g. the amount of rainfall light intensity and light duration etc.) it is not possible to cite temperature as the causal factor associated weth controlling phytoplankton abundance at our two sample sites. Our data support the rather controversial notion that percentage-wise, there are relatively more harmful bloom forming species in nutrient-rich coastal waters than there are in the world's oceans. 16% of the dinoflagellate species and 10.3% of the diatom species observed at our two sample sites were classed as harmful. These percentages were higher than those cited by Sournia (1995) for the worlds oceans (9.6% and 6.8% respectively). This raises the possibility that there are relatively more toxic species in the nutrient-rich coastal waters of the world than there are in the mid ocean nutrient-poor areas of the world. Some reasons for this are briefly discussed.     

Establishing the thermal threshold of the tropical mussel Perna viridis in the face of global warming

With increasing recognition that maximum oxygen demand is the unifying limit in tolerance, the first line of thermal sensitivity is, as a corollary, due to capacity limitations at a high level of organisational complexity before individual, molecular or membrane functions become disturbed. In this study the tropical mussel Perna viridis were subjected to temperature change of 0.4 °C per hour from ambient to 8–36 °C. By comparing thermal mortality against biochemical indices (hsp70, gluthathione), physiological indices (glycogen, FRAP, NRRT) and behavioural indices (clearance rate), a hierarchy of thermal tolerance was therein elucidated, ranging from systemic to cellular to molecular levels. Generally, while biochemical indices indicated a stress signal much earlier than the more integrated behavioural indices, failure of the latter (indicating a tolerance limit and transition to pejus state) occurred much earlier than the other indices tending towards thermal extremities at both ends of the thermal spectrum.     

Seismic hazard assessment of northern Pakistan

This article presents probabilistic seismic hazard analyses of northern Pakistan region carried out to produce macro-seismic hazard maps for the region that define new regional ground motion design parameters for 95-, 475-, 975- and 2475-year return period earthquakes as regional contour maps and horizontal uniform hazard at important cities. The Cornell–McGuire approach (Cornell in Bull Seismol Soc Am 58(05):1583–1606, 1968; McGuire in FORTRAN computer program for seismic risk analysis. US Geological Survey, Open file Report, 76-6768, 1976) is used to carry out the analyses at 0.1° rectangular grid. The seismotectonic model of the region used in analysis consists of shallow and deep area zones differentiated based on the focal depths of the earthquakes. Earthquake catalogue compiled and used in the analysis is a composite catalogue composed of 19,373 events. Ground motion prediction equations (GMPEs) used are calibrated using goodness-of-fitness measures and visual inspection with local strong motion data. Epistemic uncertainty in the GMPEs is taken into account through the logic tree approach. Comparison of ground motions due to deep earthquakes is made for the first time for the region. The comparison between ground motion due to shallow and deep earthquakes indicates that the seismic hazard would be underestimated if the deep earthquakes are excluded. Ground motion values obtained in this study considering all the earthquakes suggest ground motions are dominant towards the north east of the region. The proposed study indicates that the ground motion hazard values suggested by the current Building Code of Pakistan underestimate the seismic hazard. Final results of this study are in close agreement with the recent studies on the region.