一种缺氧型生物滴滤塔对硫化氢去除的最佳反应条件

取自污水处理厂二沉池活性污泥载入生物滴滤塔中,与传统生物滴滤塔对比,考察了在缺氧条件下微生物对H2S的去除效率,最适工艺运行条件及影响因素,实验结果表明,最佳工艺运行条件:温度为30℃,pH 6.0,H2S入口浓度C1=1 000 mg/m3、C2=2 000 mg/m3、C3=3 000 mg/m3,对应的最适气体流量和循环液喷淋量分别为35～55 L/h、45 L/h、55L/h和20 L/h、40 L/h、50 L/h,该生物滴滤塔最高H2S负荷率可达6.9 g/(m3.h),具有较高的H2S去除效率,最适工艺运行条件的确定对实际大中型沼气发酵池净化配套系统具有一定的指导意义。     

填埋垃圾中TOC含量的测定方法优化

垃圾的TOC含量是评价垃圾矿质腐殖化机理研究的重要指标,以本课题组模拟垃圾填埋系统中的垃圾样品为研究对象,以土壤TOC测定方法为基础,通过单因素实验和正交实验(L25(56))对垃圾样品的TOC的测定方法进行优化。结果表明,TOC测定优化条件为:风干样品(0.1±0.0005)g,Ag2SO40.075 g,0.4 mol/L(1/6K2Cr2O7)-H2SO4溶液(含1/2H2SO412.6 mol/L)10 mL,180℃的砂浴加热45 min。此条件下,RSD小于3.23%,表明该方法精密度高,可行性强。     

基于层次分析法的坦塘垃圾填埋场适宜性评价

垃圾填埋场场址的适宜性评价是生活垃圾填埋场建设和运营的前提和基础。以湖南省永州市坦塘垃圾填埋场为例,在分析研究区的地质与水文地质条件的基础上,确定了填埋场适宜性的影响因素为填埋场规模、运输条件、环境条件、建场条件和地质条件,具体包括填埋场面积及容量、综合路况条件、对地表水体污染的可能性、地形平坦程度以及场地是否处在岩溶区等条件,明确了局部地区岩溶发育是制约其适宜性的主要因素。结合垃圾填埋场的建设情况和相关规范、标准,采用层次分析法对坦塘垃圾填埋场进行适宜性评价。评价结果表明,坦塘垃圾填埋场是一个适宜场地,评价结果与实际情况相符。     

汽爆秸秆高温固态发酵沼气的研究

沼气液态深层发酵及秸秆的物理、化学和生物预处理方式存在效率低、污染重等问题。为了解决这些问题,对蒸汽爆破预处理方式以及固态发酵在玉米秸秆沼气化中的应用进行了研究。秸秆经过蒸汽爆破预处理后,在50℃的高温条件下进行固态发酵沼气,甲烷产量达到138.2 mL/g TS。通过单因素实验优化,确定最佳发酵条件为：固液比1∶7,初始pH值7.5,接种量35%,NH₄HCO₃添加量0.04 g/g干汽爆秸秆,纤维素酶用量30 IU/g干汽爆秸秆,发酵温度50℃。在上述实验条件下,汽爆秸秆的甲烷产量提高至153.0 mL/g TS,是未汽爆秸秆的2.9倍。发酵后秸秆纤维素和半纤维素的降解率分别为59.86%和67.22%。因此,蒸汽爆破预处理有助于提高秸秆的产气量和降解率。高温固态发酵不仅可以缩短发酵延迟期,提高产气效率,而且发酵结束后不会产生大量废液,对环境友好。     

A Systematic Review of Wild Burro Grazing Effects on Mojave Desert Vegetation,USA

Wild burros (Equus asinus), protected by the 1971 Wild Free-Roaming Horse and Burro Act on some federal lands but exotic animals many ecologists and resource mangers view as damaging to native ecosystems, represent one of the most contentious environmental management problems in American Southwest arid lands. This review synthesizes the scattered literature about burro effects on plant communities of the Mojave Desert, a center of burro management contentions. I classified 24 documents meeting selection criteria for this review into five categories of research: (i) diet analyses directly determining which plant species burros consume, (ii) utilization studies of individual species, (iii) control-impact comparisons, (iv) exclosure studies, and (v) forage analyses examining chemical characteristics of forage plants. Ten diet studies recorded 175 total species that burros consumed. However, these studies and two exclosure studies suggested that burros preferentially eat graminoid and forb groups over shrubs. One study in Death Valley National Park, for example, found that Achnatherum hymenoides (Indian ricegrass) was 11 times more abundant in burro diets than expected based on its availability. Utilization studies revealed that burros also exhibit preferences within the shrub group. Eighty-three percent of reviewed documents were produced in a 12-year period, from 1972 to 1983, with the most recent document produced in 1988. Because burros remain abundant on many federal lands and grazing may interact with other management concerns (e.g., desert wildfires fueled by exotic grasses), rejuvenating grazing research to better understand both past and present burro effects could help guide revegetation and grazing management scenarios.     

Hydrochemistry of urban groundwater, Seoul, Korea: the impact of subway tunnels on groundwater quality

Hydrogeologic and hydrochemical data for subway tunnel seepage waters in Seoul (Republic of Korea) were examined to understand the effect of underground tunnels on the degradation of urban groundwater. A very large quantity of groundwater (up to 63 million m³ year^− 1) is discharged into subway tunnels with a total length of 287 km, resulting in a significant drop of the local groundwater table and the abandonment of groundwater wells. For the tunnel seepage water samples (n = 72) collected from 43 subway stations, at least one parameter among pathogenic microbes (total coliform, heterotrophic bacteria), dissolved Mn and Fe, NH₄⁺, NO₃⁻, turbidity, and color exceeded the Korean Drinking Water Standards. Locally, tunnel seepage water was enriched in dissolved Mn (avg. 0.70 mg L^− 1, max. 5.58 mg L^− 1), in addition to dissolved Fe, NH₄⁺, and pathogenic microbes, likely due to significant inflow of sewage water from broken or leaking sewer pipes.Geochemical modeling of redox reactions was conducted to simulate the characteristic hydrochemistry of subway tunnel seepage. The results show that variations in the reducing conditions occur in urban groundwater, dependent upon the amount of organic matter-rich municipal sewage contaminating the aquifer. The organic matter facilitates the reduction and dissolution of Mn- and Fe-bearing solids in aquifers and/or tunnel construction materials, resulting in the successive increase of dissolved Mn and Fe. The present study clearly demonstrates that locally significant deterioration of urban groundwater is caused by a series of interlinked hydrogeologic and hydrochemical changes induced by underground tunnels.     

Field Validation of a Conservation Network on the Eastern Shore of Maryland,USA, Using Breeding Birds as Bio-Indicators

Maryland’s Green Infrastructure (GI) is a network of large, intact natural areas (hubs), interconnected by linear swaths of riparian or upland vegetation (corridors). The GI serves significant ecological functions and provides the bulk of the state’s natural support system. This study examined whether the GI as mapped does, in fact, identify Maryland’s most ecologically valuable forested lands, using forest interior dwelling birds (hereafter called “forest birds”) as bio-indicators. We conducted bird point counts within forest both inside and outside of hubs on Maryland’s Eastern Shore. We also collected a wide variety of habitat data. We found that both the condition of a forest and its surrounding landscape influenced the bird communities. On average, forest bird richness was significantly higher within hubs; furthermore, almost all sites with at least five forest bird species present were in hubs. Forest bird richness and abundance were highest in undisturbed, mature broadleaf forest with wetlands and streams nearby. We detected a significant relationship between forest bird richness and the ecological score of a finer-scale landscape assessment, focused on “cells” of about 0.1 ha in size. This field study also validated the Rapid Field Assessment (RFA) protocol developed in 2001 to assess, on the ground, the relative condition of individual sites or properties within the GI. Forest bird richness and abundance were positively correlated with the RFA community scores. Our results underscore the importance of maintaining regional biological diversity by retaining large blocks of forest, especially mature forest containing streams and wetlands.     

某水厂送水泵房选泵方案优化

对南县供水状况进行了简要的介绍,提出了修建水厂的必要性,然后从技术、运行、运行管理费用等方面对送水泵房选泵方案进行了比较,确定了最优方案.     

Sound Survey Designs Can Facilitate Integrating Stream Monitoring Data Across Multiple Programs1

Abstract: Multiple agencies in the Pacific Northwest monitor the condition of stream networks or their watersheds. Some agencies use a stream “network” perspective to report on the fraction or length of the network that either meets or violates particular criteria. Other agencies use a “watershed” perspective to report on the health or condition of watersheds. The agencies often use the same indicators and measurement protocols for data collection and often conduct monitoring in overlapping geographic regions. In these situations, agencies would like to combine data across different monitoring studies in a statistically sound manner to make regional estimates of condition. Three statistical survey design principles will facilitate combining such studies: (1) a clearly specified statistical target population of interest, including elements that comprise the population, (2) a consistent representation of that target population (such as a digital map of the stream network and watersheds), and (3) rules that incorporate randomization to guide the selection of the sample of sites on which measurements will be made. A case study illustrates the application of these design principles using two agency monitoring programs interested in combining stream channel data for different purposes: one for making network summaries and the other for evaluating watershed condition.     

东北林区火烧防火线方法研究

火烧防火线在东北林区应用广泛,是预防森林火灾的重要措施.这项工作由于受天气、可燃物、点火技术等各方面因素影响较大,应用时具有一定的风险性.本文针对火烧防火线过程中,用火条件的选择、点火技术的运用以及用火安全等方面加以分析.