A practical device for evaluating periphyton colonization dynamics in tropical shallow wetlands

Here, we have presented a field device for sampling periphyton in lentic systems, with a tropical lowland wetland in Colombia as the model system. The periphyton sampler (PS) is composed of a central soft iron pole to which rectangular woody boxes and glass slides are attached to lateral iron axes, which can be distributed at different depths. Our PS can be used to evaluate changes in the richness and density of algal communities at different scales as well as in water quality studies.     

Urban water systems under climate stress: An isotopic perspective from Berlin,Germany

Large urban areas are typically characterized by a mosaic of different land uses, with contrasting mixes of impermeable and permeable surfaces that alter “green” and “blue” water flux partitioning. Understanding water partitioning in such heterogeneous environments is challenging but crucial for maintaining a sustainable water management during future challenges of increasing urbanization and climate warming. Stable isotopes in water have outstanding potential to trace the partitioning of rainfall along different flow paths and identify surface water sources. While isotope studies are an established method in many experimental catchments, surprisingly few studies have been conducted in urban environments. Here, we performed synoptic sampling of isotopes in precipitation, surface water and groundwater across the complex city landscape of Berlin, Germany, for a large -scale overview of the spatio-temporal dynamics of urban water cycling. By integrating stable isotopes of water with other hydrogeochemical tracers we were able to identify contributions of groundwater, surface runoff during storm events and effluent discharge on streams with variable degrees of urbanization. We could also assess the influence of summer evaporation on the larger Spree and Havel rivers and local wetlands during the exceptionally warm and dry summers of 2018 and 2019. Our results demonstrate that using stable isotopes and hydrogeochemical data in urban areas has great potential to improve our understanding of water partitioning in complex, anthropogenically-affected landscapes. This can help to address research priorities needed to tackle future challenges in cities, including the deterioration of water quality and increasing water scarcity driven by climate warming, by improving the understanding of time-variant rainfall-runoff behaviour of urban streams, incorporating field data into ecohydrological models, and better quantifying urban evapotranspiration and groundwater recharge.     

自动观测与人工观测数据差异的初步分析

利用2004—2007年内蒙古地区50个地面自动气象站与人工平行观测期间的数据,对自动与人工观测的气温、相对湿度、地表温度进行了差异分析,统计了两种观测之间的对比差值。对各要素观测差异在全区的分布特点进行了分析。结果表明:自动观测与人工观测各气象要素均存在一定的差异,但大部分地区各要素的差异都在自动站误差允许范围之内;造成差异的原因是多方面的,包括仪器本身存在缺陷及观测方法不一致等。     

松嫩沙地天然草地与人工草地土壤动物的对比研究

松嫩沙地天然草地和人工草地土壤动物的对比研究表明,天然草地大型土壤动物的优势类群与人工草地优势类群数相同,但类群有差别。而中小型土壤动物的优势类群是人工草地多。天然草地大型土壤动物和中小型土壤动物的常见类群都多于人工草地,而稀有类群则相反。两种草地类型的土壤动物在土层中的垂直分布存在差异性,但基本上是随着土层加深而递减,天然草地表层的土壤动物类群数均多于人工草地,主要是受土壤营养状况和理化性质的制约。     

南北地震带地震活动强度变化特征及其神经网络模型

南北地震带是中国大陆的一条主要活动地震带, 20世纪以来有很多大地震集中发生在这条地震带上。为了进一步探讨南北地震带地震活动强度变化的规律并对其进行中期预测,在研究了南北地震带逐年最大地震强度演化特征及其机理的基础上,建立了南北地震带地震强度序列变化的一种模式,建模中采用了人工神经网络技术,并提出了一种简易实用的能够获得较隹预测效果的确定神经网络输入窗口大小的方法。结果表明: 南北地震带的地震活动具有强弱分期轮回的特征; 用人工神经网络建模的预测结果与实际资料的对比检验中误差较小,因而该模型可作为南北地震带地震活动强度变化的预测模型。     

中国对虾受精生物学的研究

于１９８８－１９９１年在青岛对中国对虾进行受精能力和受精生物学的研究。对虾采用加温和不加温培育，然后用人工授精法－－水域法和滴管法授精研究精卵受精能力；应用扫描和透射电以及石蜡切片技术，精卵的形态结构和受精过程的变化。结果表明，水域法授精，精子入水后３ｈ仍具有受精能力；卵子入水后１ｍｉｎ之内受精率最高只达６２．７％。而滴客法授精，受精率最高可达到９８％。平均值也在６０－８０％之间。保持在低温的亲虾     

大珠母贝人工育苗技术的研究

研究大珠母贝人工育苗若干技术,提出一些技术措施：亲贝强化培育促熟,人工诱导排放精卵,优选幼虫,投喂适口的饵料,适时倒池以及投放合适的采苗器等。结果表明,平均单产壳高2-3mm的幼苗8．1万粒／m3,最高可达9．3万粒／m3。     

Modelling of multi-bodies in close proximity under water waves—Fluid forces on floating bodies

This work presents two-dimensional numerical results of the dependence of wave forces of multiple floating bodies in close proximity on the incident wave frequency, gap width, body draft, body breadth and body number based on both viscous fluid and potential flow models. The numerical models were validated by the available experimental data of fluid oscillation in narrow gaps. Numerical investigations show that the large amplitude responses of horizontal and vertical wave forces appear around the fluid resonant frequencies. The convectional potential flow model is observed to un-physically overestimate the magnitudes of wave forces as the fluid resonance takes place. By introducing artificial damping term with appropriate damping coefficients μ∈[0.4, 0.5], the potential flow model may work as well as the viscous fluid model, which agree with the damping coefficients used in our previous work for the predication of wave height under gap resonance. In addition, the numerical results of viscous fluid model suggest that the horizontal wave force is highly dependent on the water level difference between the opposite sides of an individual body and the overall horizontal wave force on the floating system is generally smaller than the summation of wave force on each body.     

Streamflow generation in a headwater basin on the precambrian shield

Current conceptual runoff models hypothesize that stormflow generation on the Canadian Shield is a combination of subsurface stormflow and saturation overland flow. This concept was tested during spring runoff in a small (3.3 ha) headwater basin using: (1) isotopic and chemical hydrograph separation and (2) field mapping and direct tracing of saturated areas. Isotopic and chemical hydrograph separation indicated three runoff components: (1) pre-melt subsurface flow; (2) subsurface flow of new (event) water; and (3) direct precipitation on to saturated areas (DPS). During early thaw-freeze cycles, their relative contributions to total flow remained constant (65 per cent, 30 per cent, and 5 per cent respectively). It is hypothesized that lateral flow along the bedrock/mineral soil interface, possibly through macropores, supplied large volumes of subsurface flow (of both old and new water) rapidly to the stream channel. Much higher contributions of DPS were observed during an intensive rain-on-snow event (15 per cent of total flow). Mapping and direct tracing of saturated areas using lithium bromide, suggested that saturated area size was positively correlated to stream discharge but its response lagged behind that of discharge. These observations suggest that the runoff mechanisms, and hence the sources of stream flow, will vary depending on storm characteristics.     

Effects of small external forces on the planar oscillation of a cable connected satellites system

The effects of small external dissipative and disturbing forces on the non-linear planar oscillation of a cable connected satellites system in the central gravitational field of earth have been studied. Typical non-linear oscillation's phenomena arizing from the aforesaid external forces are shown to take place. The presence of these forces enables the application of asymptotic methods of the theory of non-linear oscillations due to Bogoliubov and Mitropolsky to the equation characterizing the non-linear oscillation of the system.