HYDROLOGIC EFFECTS OF THE TONKAWA CREEK FLOOD ABATEMENT PROGRAM1

ABSTRACT: Floodwater-retarding impoundments, controlling 68 percent of the drainage area of Tonkawa Creek, a Washita River tributary in southwestern Oklahoma, have reduced the total flow volume about 36 percent over a 5-year period. Analyses showed the reduction occurred primarily in the less-than-2.5-cfs flow range, indicating the base flow regime has been altered. However, channelizing the downstream, mild-sloped, 3.6 miles of Tonkawa Creek that flows across a Washita River terrace increased the flow volume fourfold at the outlet. A double-masscurve analysis of water yield from a 1,127-square-mile Washita basin segment versus an untreated tributary showed the yield has not changed after 25 percent of the tributary area had been treated. Therefore, the flow reduction caused by structures is being offset by increased yields from channelization.     

Subcellular distribution and toxicity of cadmium in Potamogeton crispus L

The submerged macrophyte Potamogeton crispus L. was subjected to varying doses of cadmium (0, 20, 40, 60 and 80 μM) for 7 d, and the plants were analyzed for subcellular distribution of Cd, accumulation of mineral nutrients, photosynthesis, oxidative stress, protein content, and ultrastructural distribution of calcium (Ca). Leaf fractionation by differential centrifugation indicated that 48-69% of Cd was accumulated in the cell wall. At all doses of Cd, the levels of Ca and B rose and the level of Mn fell; the levels of Fe, Mg, Zn, Cu, Mo, and P rose initially only to decline later. Exposure to Cd caused oxidative stress as evident by increased content of malondialdehyde and decreased contents of chlorophyll and protein. Photosynthetic efficiency, as indicated by the quenching of chlorophyll a fluorescence (Fv/Fm, Fo and Fm), decreased significantly, the extent of decrease being directly proportional to the concentration of Cd. Increased amounts of precipitates of calcium were noticed in the treated plants, located either outside the cell membrane or in chloroplasts, mitochondria, the nucleus, and the cytoplasm whereas control plants showed small deposits of the precipitates around surface of the vacuole membrane and in the intercellular space but rarely in the cytoplasm. Photosynthetic efficiency and oxidative stress could be used as indicators of physiological end-points in determining the extent of Cd phytotoxicity.     

单体米黄大理石矿粉对小麦产量及各器官重金属含量的影响

采用盆栽法,研究大理石矿粉对小麦产量及对成熟期小麦根、茎叶、果实中重金属含量的影响。结果表明:添加大理石矿粉会显著影响小麦的生长及产量(P<0.05),添加矿粉的量不大于60g/kg时,小麦的结实小穗数、穗粒数、千粒重和产量随添加量的增加而增加,而含量再继续增大时,对小麦产量的促进作用将减弱;低含量的大理石矿粉能缓解Pb、Cu、Zn对小麦的毒害,而高含量的对小麦的影响各异,小麦各器官中重金属Cd、Cr与添加大理石矿粉含量呈显著正相关;重金属对小麦各器官的影响排序,根:Cd>Cr>Pb>Cu>Zn,茎叶:Cd>Cr>Cu>Pb>Zn,果实:Cd>Cr>Pb>Zn>Cu。在大理石开采区应该采取一定的措施,避免大量的大理石矿粉散入周围的耕地。     

Managing forest ecosystem services for hydropower production

In many countries, hydropower development is rapidly becoming a focus of green growth policies. This represents a significant opportunity for ecosystem services-based land management that integrates environmental and development goals to benefit the hydropower sector and support economic growth. In this study, we present an approach for targeting ecosystem-provision investment in hydropower catchments coupled with hydrologic modeling to quantify the benefits of soil and water conservation activities. We demonstrate the application of this approach in five hydropower facility catchments in the state of Himachal Pradesh, India. The results show that there is a high potential for targeted soil and water conservation to increase sediment retention services that benefit hydropower facilities (up to a 44% reduction in sediment transported from uplands into streams), although this benefit is distributed non-uniformly across catchments and levels of investment. The extent to which services can be improved is strongly driven by current land use and management practices that impact how and where conservation activities can be located. Iterative use of the method described here, in a process of stakeholder engagement and capacity-building, enables policy makers to determine the optimal mix of land management strategies and budget allocation to maximize service improvements that support hydropower production.     

摇动床生物膜反应器和活性污泥法组合技术处理高浓度有机废水的研究

利用摇动床生物膜反应器(简称摇动床)技术具有的容积负荷高与污泥产量低的优点,在普通活性污泥池的前部填充高性能丙烯酸树脂纤维(Biofringe)填料,研究了摇动床和活性污泥法组合技术处理高浓度有机废水的有效性。结果表明,该组合技术具有很强的有机物去除能力,当进水COD平均质量浓度由1500mg/L上升到2514mg/L时,出水COD的平均去除率基本保持在96%以上;整个运行阶段的出水COD浓度均满足《污水综合排放标准》(GB8978—1996)的二级标准;当进水NH4+-N浓度增加时,NH4+-N的去除率由99.7%降低到76.5%,但是在试验运行的整个阶段,摇动床和活性污泥法组合技术系统都表现出较强的硝化能力;活性污泥池中最高的混合液悬浮固体(MLSS)质量浓度为10625mg/L,最高MLSS约为普通活性污泥法的4倍;运行结束后的污泥产率为0.186,污泥产率仅为普通活性污泥法的50%左右。     

Is the growth stimulation by low doses of glyphosate sustained over time?

The herbicide, glyphosate, has been shown to stimulate growth in a range of species when applied at doses of 5-60 g a.e. ha⁻¹, corresponding to realistic spray drift events. This study investigates growth of shoot parameters over time to detect whether the glyphosate induced growth increase was sustained and had a final effect on reproduction. The results showed that an actual biomass growth rate increase took place within the first week after spraying with glyphosate doses <60 g a.e. ha⁻¹. This initial growth boost kept treated plants larger than untreated plants for up to six weeks, but at harvest there was no significant difference between control plants and treated plants. Possible effects of glyphosate hormesis on the competitive ability of spray drift affected plants are discussed.     

Specific features of seedage in Norway spruce (Picea abies karst.) in the northern Moscow region

Climatic characteristics of the northern Moscow region and the periodicity of seedage in Norway spruce were analyzed retrospectively. The relationship between the intensity of seedage and weather conditions in the period before seedage was revealed.     

A SUPERCRITICAL FLUME FOR MEASURING SEDIMENT-LADEN STREAMFLOW1

ABSTRACT: After 25 years of operation on ephemeral streams in the semiarid Southwest, this supercritical flume has provided more than 350 station-years of reliable streamflow data, even under freezethaw conditions experienced at elevations of 1,500 to 2,100 m, in Arizona. The flume has also provided streamflow data during flood periods produced by high intensity summer thunderstorm conditions, where considerable sediment and other debris was moved downstream.     

环境烟草烟气粒径分布及其对光散射的影响

为了测量典型办公室内环境中环境烟草烟气悬浮颗粒物的数浓度和粒径分布变化,以及其对颗粒光散射的影响,在6.8 m×3.2mx2.8 m的试验间进行试验,采用测量范围为5～1 000 nm的DMS500扫描电迁移率粒径谱仪进行粒径测量.结果表明,不同卷烟样品的烟气粒径分布曲线近似,都可以用对数正态分布函数来描述.4种卷烟样品粒径分布及参数变化速率相似,在4 800 s内数中值粒径CMD平均值从105 nm增大至155 nm,几何标准差GSD平均值从1,58减小至1.45,CMD和GSD的变化趋势近似符合指数函数.利用基于Mueller光散射理论的程序计算烟颗粒对散射光的影响.粒径分布的变化显著改变了颗粒散射光强度,CMD最大使散射光强度增大7倍,GSD引起的强度变化较小.综合考虑烟气颗粒数浓度降低和粒径分布的变化,散射光强度最大增大3倍.     

绿灯倒计时信号对驾驶行为的影响

为揭示绿灯倒计时信号对交叉口交通安全的影响,针对不同交通负荷与信号控制方式下的驾驶行为开展研究。选择大连市内的倒计时信号交叉口与非倒计时信号交叉口各2处,开展车辆行驶速度及不良驾驶行为调查。用数理统计方法,对比分析2类交叉口在平峰与高峰时段的车辆行驶速度特性,同时对比分析上述不同条件下闯黄灯及违规变道行为的发生数量。研究表明,绿灯倒计时信号在绿灯时间末期,会诱发一部分驾驶员加速行驶通过交叉口;绿灯倒计时信号在平峰时段对闯黄灯行为数量的影响较小,而对违规变道行为的数量有显著影响。