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.     

Behavior and prediction of photochemical degradation of chlorinated polycyclic aromatic hydrocarbons in cyclohexane

The photochemical degradation of 11 chlorinated polycyclic aromatic hydrocarbons (ClPAHs) and the corresponding 5 parent PAHs was examined to simulate the compound’s fate on aerosol surfaces. All the ClPAHs and PAHs decayed according to the first-order reaction rate kinetics. The photolysis rates of ClPAHs varied greatly according to the skeleton of PAHs; the rates of chlorophenanthrenes (ClPhes) and 1-chloropyrene were higher than those of corresponding parent PAHs, whereas chlorofluoranthenes, 7-chlorobenz[a]anthracene and 6-chlorobenzo[a]pyrene were more stable under irradiation compared to respective parent PAH. Considering the photoproducts of ClPhes detected, the oxidation could occur immediately at positions of the highest frontier electron density. Finally, the quantitative structure-property relationship models were developed for direct photolysis half-lives and average quantum yields of the ClPAHs and parent PAHs, in which the significant factors affecting photolysis were E_LUMO+1, total energy and surface area, and E_LUMO, E_LUMO − E_HOMO and total energy, respectively.     

A Bayesian strategy for combining predictions from empirical and process-based models

We present a strategy for using an empirical forest growth model to reduce uncertainty in predictions made with a physiological process-based forest ecosystem model. The uncertainty reduction is carried out via Bayesian melding, in which information from prior knowledge and a deterministic computer model is conditioned on a likelihood function. We used predictions from an empirical forest growth model G-HAT in place of field observations of aboveground net primary productivity (ANPP) in a deciduous temperate forest ecosystem. Using Bayesian melding, priors for the inputs of the process-based forest ecosystem PnET-II were propagated through the model, and likelihoods for the PnET-II output ANPP were calculated using the G-HAT predictions. Posterior distributions for ANPP and many PnET-II inputs obtained using the G-HAT predictions largely matched posteriors obtained using field data. Since empirical growth models are often more readily available than extensive field data sets, the method represents a potential gain in efficiency for reducing the uncertainty of process-based model predictions when reliable empirical models are available but high-quality data are not.     

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。     

水解酸化-A2O污泥减量工艺的运行性能研究

生物处理单元采用水解酸化、多级串联接触曝气、连续流的除磷脱氮A2／O工艺,并辅以外排厌氧富磷污水侧流除磷,开发了一个新型的具有强化除磷脱氮功能的污泥减量HA—A／A—MCO工艺。用该工艺处理校园生活污水发现,在SRT60d、进水COD316～407mg／L、NH4＋-N30～40mg／L、TN35～53mg／L、TP8—12mg／L的条件下,出水COD≤18mg／L、NH4＋-N≤2．1mg／L、TN≤10．3mg／L、TP≤0．44mg／L。研究还发现,水解酸化池处理产生的VFA能有效促进生物除磷脱氮,导致厌氧释磷量达57mg／L,进入化学除磷池的侧流液量仅相当于进水量的13％;系统最主要的脱氮形式是SND和缺氧反硝化,SND脱氮占脱氮总量的50％,缺氧反硝化占26％;HA-A／A—MCO系统有效实现了生物相分离,并利用生物捕食作用获得较低的污泥产率,0．1gMLSS／gCOD。     

电子设备机房空调供冷量探讨

电子设备机房的空调供冷量与普通办公室相差甚远 ,介绍了其计算方法和影响空调制冷设备实际制冷量的因素     

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。     

Seawater Intrusion and Sustainable Yield of Basal Aquifers1

Liu, Clark C.K. and John J. Dai, 2012. Seawater Intrusion and Sustainable Yield of Basal Aquifers. Journal of the American Water Resources Association (JAWRA) 48(5): 861‐870. DOI: 10.1111/j.1752‐1688.2012.00659.x Abstract: Basal aquifers, in which freshwater floats on top of saltwater, are the major freshwater supply for the Hawaiian Islands, as well as many other coastal regions around the world. Under unexploited or natural conditions, freshwater and the underlying seawater are separated by a relatively sharp interface located below mean sea level at a depth of about 40 times the hydraulic head. With forced draft, the hydraulic head of a basal aquifer would decline and the sharp interface would move up. It is a serious problem of seawater intrusion as huge amounts of freshwater storage is replaced by saltwater. Also, with forced draft, the sharp interface is replaced by a transition zone in which the salinity increases downward from freshwater to saltwater. As pumping continues, the transition zone expands. The desirable source‐water salinity in Hawaii is about 2% of the seawater salinity. Therefore, the transition zone expansion is another serious problem of seawater intrusion. In this study, a robust analytical groundwater flow and salinity transport model (RAM2) was developed. RAM2 has a simple mathematical structure and its model parameters can be determined satisfactorily with the available field monitoring data. The usefulness of RAM2 as a viable management tool for coastal ground water management is demonstrated by applying it to determine the sustainable yield of the Pearl Harbor aquifer, a principal water supply source in Hawaii.     

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.     

西藏草地生长季产草量动态变化及可持续发展策略

论文利用西藏地区草地产草量实际调查数据和NDVI数据集,建立西藏草地产草量估算模型,定量分析了1987—2010年间西藏草地生长季的产草量时空变化特征。研究表明：1987—2010年间,那曲地区草地产草量增速最大,增幅为54%,而拉萨地区草地产草量呈现负增长,减幅为4%。在空间分布上,总体呈现由西北向东南递增趋势;产草量增加的地区主要位于西藏中北部,南部多为产草量减少的区域。西藏草地产草量增加的区域面积占草地总面积的76.04%;产草量减少的区域面积仅占全区草地面积的23.96%。在年代际变化上,1996—2006年10 a间西藏产草量增加的区域面积显著大于减少的区域面积。为了改善西藏草地生态系统状况,进一步提高草地产草量,论文从草地开发利用、空间格局、病虫害防治和退耕还草生态补偿等方面提出西藏草地资源可持续发展策略。