Fast clogging problem of open check dams and a new type suggestion:curved footed type open check dam

Driftwood is one of the important physical components in mountainous rivers which causes severe hazards due to the clogging of bridges, culverts,and narrow sections during floods. Therefore, the understanding of driftwood dynamics and mitigation measures are crucial for managing wood in rivers.Open check dams are the most commonly used engineering measure for preventing driftwood from reaching downstream areas. Nevertheless, these open check dams frequently lose their sediment transport function...     

2010～2019年文山州气象灾害特征分析

利用2010～2019年文山州气象灾害的灾情资料,采用统计分析法和归一化法对文山州气象灾害的时空分布特征及其带来的综合损失分布特征进行了分析.结果表明:2010～2019年文山州气象灾害造成的直接经济损失及其占GDP比例和灾害发生频次均呈下降趋势,但死亡人口呈上升趋势.洪灾是影响文山州最主要的气象灾害.气象灾害各月均有...     

盆地构造图三维可视化系统开发的实例介绍

传统的二维构造图难于直观地描述地质构造的空间形态。综合利用VB、VC和OPENGL环境设计的盆地构造图三维可视化系统将构造图上涉及的要素分成点、线、面、区等不同类型,每个类型数据又都由空间数据和属性数据两部分组成,并用数据库方式管理这些数据。系统除了可将各构造要素以三维方式显示外,还可以利用测井数据和剖面图恢复三维地层;同时允许用户与屏幕图形进行交互,从而实现对图形的切割操作。显示成果可以以栅格图形或AVI录像形式输出。通过几个用该系统输出的三维构造图的实例说明该系统基本能满足盆地构造图三维显示的需要。     

一种提高探测三地质体能力的处理直流电阻率数据的新方法

用一种简单的处理方法来处理用施伦贝尔热和赤道偶极装置在三维构造上采取的数据。三维体的信号可通过从总效应里减去水平层的效应而得到加强,由于在层六状大地上施伦贝尔热和赤道偶极装置所测的视电阻率是相同的,把两组测量数据相减所和的剩余电阻率主要受地质体控制。通过不同的例子显示了方法的有效性     

Toxicity evaluation by using intact sediments and sediment extracts

The toxicity of intact sediments and sediment extracts, from both an uncontaminated site and a site contaminated by pulp-mill effluents, was tested in a five months study. The deposit-feeding amphipod Monoporeia affinis was exposed in soft-bottom flow-through water microcosms. To examine potential toxicity a set of reproduction endpoints was used including fecundity and different embryo aberrations such as malformed eggs. Among extracts, the aliphatic/monoaromatic and diaromatic fractions along with the total extract were shown to cause the highest toxicity measured as malformed eggs, while the polyaromatic fraction caused toxicity at background levels. A comparison between sediment extracts and pulp mill contaminated intact sediment, however, showed no toxicity of the intact sediment. Thus, the extraction procedure seems to increase bioavailability and subsequently toxicity as compared to the intact sediments in situ. In toxicity testing using fractionated extracts of sediments in a toxicity identification evaluation (TIE) procedures, caution should therefore be taken when assessing bioavailable contaminants in contaminated areas. This should be taken in account both in determining remediation priorities as well as in ecological risk assessments.     

Dipole anomaly in the Arctic atmosphere and winter Arctic sea ice motion

Arctic sea ice, an important component of the cli- mate system, has received significant attention re- cently. Arctic sea ice variation is an important indica- tor of changes in the climate system, such as global change and polar amplification, and observation and climate modeling suggests that sea ice can itself be an agent of climate change[1―4]. Previous studies[3,5] have shown that sea ice influences the surface and atmos- pheric boundary layer temperature. Potentially more important is t…     

Tolerance and accumulation of hexavalent chromium by two seaweed associated aspergilli

Marine seaweed (Eucheuma sp.) associated strains of Aspergillus flavus and Aspergillus niger were tested for their Cr(VI) tolerance. Both the isolates showed luxuriant growth in different concentrations of Cr(VI), i.e., 25, 50 and 100 ppm. There was no marked variation in the dry weight of control and test isolates, which indicated that both the isolates can tolerate a wide range of hexavalent chromium and their application for bioremediation purpose can be envisaged as XRF data revealed both the isolates accumulated more than 25% of the chromium supplied. A. flavus invariably exhibited higher accumulation potential.     

Avoidance response of sediment living amphipods to zinc pyrithione as a measure of sediment toxicity

An avoidance test was developed using non-cultured individuals of the sediment dwelling amphipod Monoporeia affinis. As test substance we used zinc pyrithione, an antifouling agent and a common shampoo ingredient. The toxicity to Daphnia and fish is well known but sediment toxicity of this very hydrophobic compound is less known. The preference of juvenile M. affinis was tested in jars, each including 12 petri dishes. In each replicate, half of the petri dishes contained sediment mixed with six concentrations ranging from 0 to 10microg zinc pyrithione per L sediment and half of the petri dishes contained the corresponding sediment-substance mixture plus an extra food addition. The amphipods significantly avoided petri dishes with the three highest concentrations of zinc pyrithione and the calculated EC(50) was 9.65microgL(-1) sediment. No difference in mortality was observed between concentrations. Using the avoidance behaviour in sediment toxicity testing is a simple and cost-effective screening for toxicants.