Medium-term responses of rocky bottoms to sewage discharges from a deepwater outfall in the NE Atlantic

An investigation on the effects of deepwater outfall discharges on the status of rocky reef communities was carried out. The sanitation system was found to be an environmentally suitable option for the protection of those habitats situated in high energy coastal environments. Sediments occurring between the predominating rocky substrates showed low values of the fine fraction (<63microm) and organic matter content. In addition, high average concentrations of Cd, Hg and Zn were found in these sediments, though these values were similar to those registered in non-affected sites, far away from the outfall. On the other hand, those assemblages typical of hard substrates that settled near the outfall showed an increase in total richness and abundance of macroinvertebrates. Moreover, the average number of species of each taxonomic group, a good indicator of the maintenance of the previous trophic structure, only varied considerably over time at the rip-rap protection. In a global context, those changes were not directly related to the discharge disturbances, but to the natural variability or the successional processes occurring within those communities. Only communities dwelling in the rip-rap protection area were affected by the proximity of the discharges.     

Biodiversity and invasibility: Distribution patterns of invasive plant species in the Himalayas,Nepal

Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.     

基于气象数据的地基雷达大气扰动校正方法研究

大气扰动是影响地基雷达(Ground-based SAR,GBSAR)系统监测精度的主要因素,文中研究大气扰动对GBSAR相位的影响及相应的补偿方法。实验以自制的角反射器作为监测目标,利用气象数据补偿法改正角反射器相位,用观测区域的温度、气压和湿度建立大气折射模型,估算出大气折射率的变化来校正大气扰动误差。结果表明,文中方法能有效地剔除大气扰动相位,达到改善监测精度的效果。     

GAINS中重力传感器信息的扰动改正

重力辅助惯性导航系统GAINS(Gravity Aided Inertial Navigation System)是利用地球物理特征信息重力来完成水下运动载体的辅助惯性导航与定位.为实现重力匹配以校正惯性导航随时间累积的误差,首先必须对重力传感器输出信息进行扰动改正.分析了水下运动状态下重力传感器受到的各种重力扰动,如垂直扰动加速度、水平扰动加速度以及厄特弗斯效应影响所产生的原因,研究了扰动误差模型与INS导航精度之间的关系,并通过计算,提出了可直接以INS输出数据而无需其它外部有源导航信息进行扰动分离的方法.     

崩落法开采引起的岩层移动时效性研究

崩落法开采的金属矿山往往会伴随着一系列的地质灾害现象。为保证矿区安全生产,开展崩落法开采引起的岩层移动的时效性研究具有重要意义。以程潮铁矿西区下盘为研究对象,通过将地表10多年GPS监测数据的整理分析,并与现场破坏调查结果和工程地质条件相结合,进而探究不同分区下岩层移动的时效行为。研究结果表明：岩层移动的时效行为与其破坏过程有着密切的关系,不同分区下的岩层移动的时效行为是不同的,可分为初始变形、渐进变形、加速变形和残余变形共4个阶段,分别对应着稳定状态、临界状态、失稳状态以及采矿结束后的蠕变状态;初始变形阶段对应着岩体的初始蠕变过程,渐进变形阶段反映了岩体抵抗自身变形的过程,加速变形阶段与深部破坏面的形成和强烈的应力释放有关;崩落碎石在采矿作业停止后失去了流动空间,在岩体变形挤压下会对围岩提供支撑力进而限制了岩层移动的进一步发展;残余变形时间由岩体的蠕变特性和崩落碎石的压密过程所控制,倾倒滑移区因需要经历一个额外的碎石压密过程而导致残余变形时间更长。     

台风“利奇马”对钻孔体应变的扰动分析——以浙江地区为例

利用台风“利奇马”过境浙江期间,岱山地震台、东阳地震台钻孔体应变数据,采用数据滤波和线性回归等方法,分析了这2个台站钻孔体应变对台风的响应特征。结果表明,东阳地震台受台风引起的低气压的影响,钻孔体应变与气压同步变化;而岱山地震台受低气压和降水的共同影响,钻孔体应变与气压在变化的相关性和同步性上均有差异。气压和降水导致钻孔体应变的变化量可以通过负载力学模型进行估算求解。     

基于结构水文地质学的采掘诱发高势能突水溃砂主动防控

在谷德振先生“水文地质结构”学术思想指引下,本文提出建立结构水文地质学的设想,论述了其基础理论框架。从方法论角度将矿山水害防控分为被动防控和主动防控两种方法。以结构水文地质学指导煤矿高势能突水溃砂防控,分析了被动防控可能产生突水溃砂灾害的机理; 提出了主动地质工程防控的原理,包括地质材料性质改造、结构隔水性能重构、赋存水动力环境改造、减轻采掘诱发覆岩破坏等具体方法。抛砖引玉,以期催生符合中国矿山防治水实践需要的创新理论和方法。     

SIMULATION OF BOUNDARY LAYER EFFECTS ON A HEAVY RAINFALL EVENT CAUSED BY A MESOSCALE CONVECTIVE SYSTEM OVER THE YELLOW RIVER MIDSTREAM AREA

A heavy rainfall event caused by a mesoscale convective system (MCS), which occurred over the Yellow River midstream area during 7–9 July 2016, was analyzed using observational, high-resolution satellite, NCEP/NCAR reanalysis, and numerical simulation data. This heavy rainfall event was caused by one mesoscale convective complex (MCC) and five MCSs successively. The MCC rainstorm occurred when southwesterly winds strengthened into a jet. The MCS rainstorms occurred when low-level wind fields weakened, but their easterly components in the lower and boundary layers increased continuously. Numerical analysis revealed that there were obvious differences between the MCC and MCS rainstorms, including their three-dimensional airflow structure, disturbances in wind fields and vapor distributions, and characteristics of energy conversion and propagation. Formation of the MCC was related to southerly conveyed water vapor and energy to the north, with obvious water vapor exchange between the free atmosphere and the boundary layer. Continuous regeneration and development of the MCSs mainly relied on maintenance of an upward extension of a positive water vapor disturbance. The MCC rainstorm was triggered by large range of convergent ascending motion caused by a southerly jet, and easterly disturbance within the boundary layer. While a southerly fluctuation and easterly disturbance in the boundary layer were important triggers of the MCS rainstorms. Maintenance and development of the MCC and MCSs were linked to secondary circulation, resulting from convergence of Ekman non-equilibrium flow in the boundary layer. Both intensity and motion of the convergence centers in MCC and MCS cases were different. Clearly, sub-synoptic scale systems in the middle troposphere played a leading role in determining precipitation distribution during this event. Although mesoscale systems triggered by the sub-synoptic scale system induced the heavy rainfall, small-scale disturbances within the boundary layer determined its intensity and location.     

Trophic modeling of the Northern Humboldt Current Ecosystem, Part II: Elucidating ecosystem dynamics from 1995 to 2004 with a focus on the impact of ENSO

The Northern Humboldt Current Ecosystem is one of the most productive in the world in terms of fish production. Its location near to the equator permits strong upwelling under relatively low winds, thus creating optimal conditions for the development of plankton communities. These communities ultimately support abundant populations of grazing fish such as the Peruvian anchoveta, Engraulis ringens. The ecosystem is also subject to strong inter-annual environmental variability associated with the El Niño Southern Oscillation (ENSO), which has major effects on nutrient structure, primary production, and higher trophic levels. Here our objective is to model the contributions of several external drivers (i.e. reconstructed phytoplankton changes, fish immigration, and fishing rate) and internal control mechanisms (i.e. predator-prey) to ecosystem dynamics over an ENSO cycle. Steady-state models and time-series data from the Instituto del Mar del Perú (IMARPE) from 1995 to 2004 provide the base data for simulations conducted with the program Ecopath with Ecosim. In simulations all three external drivers contribute to ecosystem dynamics. Changes in phytoplankton quantity and composition (i.e. contribution of diatoms and dino- and silicoflagellates), as affected by upwelling intensity, were important in dynamics of the El Niño of 1997–98 and the subsequent 3 years. The expansion and immigration of mesopelagic fish populations during El Niño was important for dynamics in following years. Fishing rate changes were the most important of the three external drivers tested, helping to explain observed dynamics throughout the modeled period, and particularly during the post-El Niño period. Internal control settings show a mix of predator–prey control settings; however a “wasp-waist” control of the ecosystem by small pelagic fish is not supported.