湖滨带开发利用对大型底栖动物群落结构的影响:以洪泽湖为例

湖滨带是湖泊与陆地生态系统间非常重要的生态过渡带,能够保障周围生态系统结构的完整以及功能的正常发挥.随着湖滨带被持续开发与利用,人为干扰对湖滨带的影响逐渐增强.大型底栖动物是淡水生态系统的重要生物类群之一,也是物质循环和能量流动的主要环节,起着承上启下的关键作用.为了解湖滨带开发利用对大型底栖动物群落结构的影响,2020年8月对洪泽湖湖滨带49个样点的大型底栖动物进行调查.共采集到大型底栖动物49种,隶属3门7纲17目26科44属,各样点大型底栖动物的密度差别较大,介于6.67~1386.67 ind./m²之间,整体上呈现西北高,东南低的趋势.相似性分析结果表明,河口型湖滨带和大堤型湖滨带与其他类型湖滨带差异显著,而围网型、圈圩型和光滩型3种湖滨带类型之间的大型底栖动物群落差异均不显著.相似性百分比分析结果表明,腹足纲的环棱螺属是造成不同湖滨带类型差异的主要物种.典范对应分析结果表明,悬浮物（SS）、溶解态总氮、pH、透明度（SD）、浊度、水生植物盖度和扰动指数对大型底栖动物群落有显著影响.考虑不同湖滨带宽度的开发利用情况,发现湖滨带开发利用200 m范围内,物种-环境解释率最高,说明200 m湖滨带范围内的开发利用情况对大型底栖动物的影响最大,对湖滨带200 m范围内的开发利用应该加强管控.结构方程模型表明湖滨带开发利用主要通过影响水生植物盖度、总氮、硝态氮、叶绿素a、SS、SD等进而影响大型底栖动物,且围网也会直接影响大型底栖动物群落结构.     

利用测井资料研究储层的孔隙结构

以岩芯孔隙结构分析为基础，通过分析表征孔隙结构参数的静态模型， 依据现场数据得到了求解孔隙结构参数的白化方程，从而阐明了用测井资料 求解孔隙结构参数的可行性。通过2个实例的分析表明，可以用声波时差、感 应电导、自然电位等常规测井方法准确地求取孔喉半径、喉道分选系数等孔 隙结构参数。为储层微观非均质性研究打下了基础以及为储层评价提供了有 用的手段，直接指导了油田生产及调整开发措施的实施。     

伪谱法在常Q粘弹介质地震波场模拟中的应用效果

本文采用伪谱法推导了常Q粘弹介质中地震波场的运动方程和波动方程,并进行了地震波场数值正演模拟,模拟结果达到了其它模拟方法同样的效果.但与其它方法相比,采用伪谱法不仅简洁明了,更便于理解;更重要的是它比以往的方法更具有通用性.由此可以说,如果采用伪谱法模拟其它更复杂的粘弹介质模型时,完全可以避免不必要的而且烦杂的数学推导过程;直接将体积松弛模量和剪切松弛模量代入即可得其波动方程.     

河流大型底栖动物对环境压力的响应:以太湖、巢湖流域为例

为了解河流大型底栖动物对环境压力的响应关系,以人类干扰程度不同的太湖流域和巢湖流域为研究区,系统调查区域内河流大型底栖动物,结合水体、沉积物理化数据及生境质量状况,运用空间分析和多元统计分析等方法,探讨了大型底栖动物多样性及典型物种对关键环境因素的响应规律.结果表明,太湖流域和巢湖流域的环境质量和大型底栖动物群落结构均差异较大,巢湖流域的生境质量优于太湖流域,巢湖流域平原区部分点位的水体营养盐(特别是氮浓度)高于太湖流域平原区.巢湖流域丘陵区的敏感型物种(主要为水生昆虫)密度远高于太湖流域丘陵区,太湖流域丘陵区的耐污型物种(寡毛纲)平均密度稍高于巢湖流域丘陵区,而巢湖流域平原区的寡毛纲霍甫水丝蚓(Limnodrilus hoffmeisteri)和苏氏尾鳃蚓(Branchiura sowerbyi)平均密度远高于太湖流域平原区.广义加性模型建立的响应关系曲线表明,栖境多样性和总氮浓度可以作为生物多样性的指示因子.铜锈环棱螺(Bellamya aeruginosa)、椭圆萝卜螺(Radix swinhoei)、河蚬(Corbicula fluminea)、霍甫水丝蚓、苏氏尾鳃蚓、黄色羽摇蚊(Chironomus flaviplumus)等特征物种与特定环境因子的响应关系显著,这些物种也可以作为环境监测的指示物种.底栖动物环境梯度的响应曲线能够定量地描述底栖动物群落对环境因子的响应关系,有利于深入了解水体水质、营养状态及生境质量与大型底栖动物群落结构的相关关系,进而预测不同人为干扰下大型底栖动物群落结构的变化趋势和演替过程.     

The von Kármán constant determined by large eddy simulation

The present study explores the extent to which the logarithmic region of the adiabatic atmospheric boundary layer can be modeled using a three-dimensional large eddy simulation. A value of the von Kármán constant (_LES) is obtained by determining the slope of a logarithmic portion of the velocity profile. Its numerical value is found to be dependent on the value of the Smagorinsky-Model Reynolds number, Re_SM: the value of _LES increases with Re_SM. Results indicate that _LES approaches a value of 0.35 as Re_SM reaches about 7.75 × 10⁵ for the largest domain. The sensitivity of _LES to the profile region over which it is evaluated has been tested. Results show that _LES is not sensitive to the depth of this evaluation region when we employ five grids above the sub-grid buffer layer where sub-grid-scale effects dominate. The maximum _LES is obtained when the lower boundary of the evaluation region is just above the top of the sub-grid-scale buffer layer. This result is consistent with modelled mean speed and resolved-scale shear stress profiles.     

水质监测浮标及其传感器的防污染措施

近岸、河口和海湾水质浮标监测越来越受到关注, 但目前有关水质监测传感器的防污染技术的报道还很少。文章介绍了在珠江口水质监测浮标中使用的几种防污染方法。对于有光学窗口的监测仪器, 采用自动防污染装置可以清除窗口表面的污染物。对于不便于采用自动防污染刷的传感器, 根据情况分别采用防污染材料包络, 或者海水注入管路的防污染过滤头等方式, 也可以达到一定的防污染效果。对于长期水下观测仪器, 每隔一段时间还应进行舱体污染物的人工清洗, 以保证设备的正常使用。     

长江源区地表水资源对气候变化的响应及趋势预测

利用1961-2011 年长江源区流域水文、气象观测数据和国家气候中心2009 年11 月发布的中国地区气候变化预估数据集(2.0 版本), 通过分析长江源区流量的演变规律和揭示气候归因, 预测了未来流量可能的演变趋势。研究表明:近51 年来长江源区地表水资源总体呈增加趋势, 特别是2004 年后增加趋势显著, 并具有9a、22a 的准周期;青藏高原加热场增强, 高原季风进入强盛期, 流域降水量显著增加, 加之气候变化导致冰川融水增多, 是引起长江源区地表水资源增加的主要气候归因;根据全球气候模式预测, 在SRESA1B气候变化情景下, 未来20年长江源区地表水资源仍有可能以增加为主。     

The electrical conductivity of eclogite in Tibet and its geophysical implications

The electrical conductivity of Tibetan eclogite was investigated at pressures of 1.5–3.5 GPa and temperatures of 500–803 K using impedance spectroscopy within a frequency range of 10-1–106 Hz. The electrical conductivity of eclogite increases with increasing temperature(which can be approximated by the Arrhenius equation), and is weakly affected by pressure. At each tested pressure, the electrical conductivity is weakly temperature dependent below ~650 K and more strongly temperature dependent above ~650 K. The calculated activation energies and volumes are 44±1 kJ/mol and-0.6±0.1 cm3/mol for low temperatures and 97±3 kJ/mol and-1.2±0.2 cm3/mol for high temperatures, respectively. When applied to the depth range of 45–100 km in Tibet, the laboratory data give conductivities on the order of 10-1.5–10-4.5 S/m, within the range of geophysical conductivity profiles.     

云南地区强震前兆短期综合异常特征研究

用斜率k和相关系数r值提取云南地区水氡、 水汞、 水温、 地磁的单项短期异常, 用群体非均匀度计算方法对各手段选取的多点观测资料进行计算, 提取综合指标。 研究结果表明, 云南地区M≥5.5地震, 前兆的群体突变异常较为显著, 对M≥5.5地震有较好的短期预报效能, 并通过置信度为97.5%的R检验。     

ON EVOLUTION OF MAN—LAND SYSTEM IN OASIS—Taking Minqin Basin as a Case

Human beings have had a tremendous impact on natural ecosystems and are now the principal power to change the biosphere.It is logical that we should pay close attention to the interaction between human systems and environ-mental systems.Taking Minqin bsin ,Gansu Province,as a case,this paper focuses on the evolution of regional physic-cal environments and the cultural systems by which people maintain their relationships with those environments.This pa-per presents the conceptural framework for the man-land system.Expecting to accelerate the regional sustainable develop-ment,it also analyses the evolutionary mechanism of regional man-land system.On the basis of reviewing and analyzing the evolution of man-land system in Minqin basin,the paper also brings forward an adujusting mode for the studied area, which consists of three aspects:to build up a concept that economic growth must harmonize with environmental qualityˊs and land productivityˊs improvement;to make a whole planning and management in the drainage area;and to push for-ward the technique of water-saving irrigation and establish water-saving agricultural system. Itˊs meaningful for resource exploitation and sustainable development of Chinese northwestern arid area,which is represented by Minqin basin,by under-standing what great changes the basin has experienced is experiencing at the global background,and studying its time standing what great changes the basin has experienced and is experiencing at the global background,and studying its time order and territorial structure ,the systemˊs character and law of evolution,trend and the regulating ways to improve man-land relationship.