粉尘在巷道中的紊流传递分析

建立的粉尘在巷道中的传递方程是一个二维平流扩散输运方程。在巷道顶底板为吸收壁的条件下，导出了粉尘浓度分布函数。传统的工业沉降室沉降效率公式（横向混合模型）只是论文所列方程的一个特例。降低紊流强度和减小紊流扩散系数和纵向弥散系数均可提高沉降效率     

Large-Scale Effects of Timber Harvesting on Stream Systems in the Ouachita Mountains, Arkansas, USA

Using Basin Area Stream Survey (BASS) data from the United States Forest Service, we evaluated how timber harvesting influenced patterns of variation in physical stream features and regional fish and macroinvertebrate assemblages. Data were collected for three years (1990–1992) from six hydrologically variable streams in the Ouachita Mountains, Arkansas, USA that were paired by management regime within three drainage basins. Specifically, we used multivariate techniques to partition variability in assemblage structure (taxonomic and trophic) that could be explained by timber harvesting, drainage basin differences, year-to-year variability, and their shared variance components. Most of the variation in fish assemblages was explained by drainage basin differences, and both basin and year-of-sampling influenced macroinvertebrate assemblages. All three factors modeled, including interactions between drainage basins and timber harvesting, influenced variability in physical stream features. Interactions between timber harvesting and drainage basins indicated that differences in physical stream features were important in determining the effects of logging within a basin. The lack of a logging effect on the biota contradicts predictions for these small, hydrologically variable streams. We believe this pattern is related to the large scale of this study and the high levels of natural variability in the streams. Alternatively, there may be time-specific effects we were unable to detect with our sampling design and analyses.     

重力作用下尘粒运动的数值解法

提出了重力作用下尘粒运动的数值解法。依据尘粒的重力、浮力及所受到的阻力推出了尘粒自然沉降时的运动方程。当尘粒的运动在斯托克斯领域内时采用理论公式求解其运动轨迹,当尘粒的运动进入非斯托克斯领域内时,提出了修正斯托克斯公式的方法以达到用理论公式来近似模拟该领域内的尘粒自然沉降运动     

Activity-dependent labeling of oxygenase enzymes in a trichloroethene-contaminated groundwater site

A variety of naturally occurring bacteria produce enzymes that cometabolically degrade trichloroethene (TCE), including organisms with aerobic oxygenases. Groundwater contaminated with TCE was collected from the aerobic region of the Test Area North site of the Idaho National Laboratory. Samples were evaluated with enzyme activity probes, and resulted in measurable detection of toluene oxygenase activity (6-79% of the total microbial cells). Wells from both inside and outside contaminated plume showed activity. Toluene oxygenase-specific PCR primers determined that toluene-degrading genes were present in all groundwater samples evaluated. In addition, bacterial isolates were obtained and possessed toluene oxygenase enzymes, demonstrated activity, and were dominated by the phylotype Pseudomonas. This study demonstrated, through the use of enzymatic probes and oxygenase gene identification, that indigenous microorganisms at a contaminated site were cometabolically active. Documentation such as this can be used to substantiate observations of natural attenuation of TCE-contaminated groundwater plumes.