影响β射线测尘仪测试精度问题探讨

介绍了β射线测尘仪的工作原理，探讨了β射线测尘仪使用中影响监测精度的问题及相应的解决措施。     

无锡职教园区餐厨垃圾理化性质调查分析研究

为提高餐厨垃圾厌氧消化效率,应用理化方法分别测试了无锡职教园区大中餐、小中餐、西餐、汤锅和食堂餐厨垃圾的容重、含水率、pH值、有机干物质、含油率、盐分、氮磷含量等指标,此外,应用餐厨垃圾厌氧发酵模拟试验分析其产沼气效率.通过理化性质试验获得不同类型餐厨垃圾理化指标的异同点.通过产沼气试验可知,容积负荷由1 kgVS/m3·d逐渐提升到4 kgVS/m3·d时,日产气量从2.91 L提高到9.01 L,沼气中甲烷含量在65％以上.     

Selectivity of Nano Zerovalent Iron in In Situ Chemical Reduction: Challenges and Improvements

Nano zerovalent iron (nZVI) is a promising remediation technology utilizing in situ chemical reduction (ISCR) to clean up contaminated groundwater at hazardous waste sites. The small particle size and large surface area of nZVI result in high reactivity and rapid destruction of contaminants. Over the past 20 years, a great deal of research has advanced the nZVI technology from bench‐scale tests to field‐scale applications. However, to date, the overall number of well‐characterized nZVI field deployments is still small compared to other alternative remedies that are more widely applied. Apart from the relatively high material cost of nZVI and questions regarding possible nanotoxicological side effects, one of the major obstacles to the widespread utilization of nZVI in the field is its short persistence in the environment due to natural reductant demand (NRD). The NRD for nZVI is predominantly due to reduction of water, but other reactions with naturally present oxidants (e.g., oxygen) occur, resulting in situ conditions that are reducing (high in ferrous iron phases and H₂) but with little or no Fe(0). This article reviews the main biogeochemical processes that determine the selectivity and longevity of nZVI, summarizes data from prior (laboratory and field) studies on the longevity of various common types of nZVI, and describes modifications of nZVI that could improve its selectivity and longevity for full‐scale applications of ISCR. © 2016 Wiley Periodicals, Inc.     

Effects of sulfate-reducing bacteria on methylmercury at the sediment–water interface

Sediment cores(containing sediment and overlying water) from Baihua Reservoir(SW China)were cultured under different redox conditions with different microbial activities, to understand the effects of sulfate-reducing bacteria(SRB) on mercury(Hg) methylation at sediment–water interfaces. Concentrations of dissolved methyl mercury(DMe Hg) in the overlying water of the control cores with bioactivity maintained(BAC) and cores with only sulfate-reducing bacteria inhibited(SRBI) and bacteria fully inhibited(BACI) were measured at the anaerobic stage followed by the aerobic stage. For the BAC and SRBI cores, DMe Hg concentrations in waters were much higher at the anaerobic stage than those at the aerobic stage, and they were negatively correlated to the dissolved oxygen concentrations(r =- 0.5311 and r =- 0.4977 for BAC and SRBI, respectively). The water DMe Hg concentrations of the SRBI cores were 50% lower than those of the BAC cores, indicating that the SRB is of great importance in Hg methylation in sediment–water systems, but there should be other microbes such as iron-reducing bacteria and those containing specific gene cluster(hgc AB), besides SRB,causing Hg methylation in the sediment–water system.     

基于GIS的东北农田畜禽粪便施用适宜性分析

东北三省是我国重要的粮食生产和工业基地.近年来,随着经济发展增速加快和产业结构调整力度加大,畜禽养殖业发展迅速,畜禽粪便产生量也快速增加.如何合理处置和利用畜禽粪便对东北三省的农业生产和环境保护都具有重要意义.本研究基于GIS平台,从自然、环境、社会和经济等多方面对东北三省畜禽粪便农田施用的适宜性进行了定量分析和评价.结果表明,东北三省78.9%的耕地适宜施用畜禽粪便,总面积为211942.7km2,主要分布在黑龙江和吉林省的大部分地区.总体来看,与居民区、水体和道路之间的禁施距离,是限制东北三省畜禽粪便耕地施用的关键因子,降雨量差异是影响耕地施用畜禽粪便适宜性地区差异的主要因子.结合适宜施用畜禽粪便的耕地面积和现有畜禽养殖水平,以畜禽粪便排放P2O5为评价指标,36个城市的养殖可发展潜力从四平市超出耕地负荷181.3万头到齐齐哈尔市1120.3万头的盈余,差异较大.从区域分布看,东部区域还有284.2万头的养殖发展空间,西部地区的辽宁中部和吉林中部近一半城市畜禽养殖量已经超过耕地可承载能力,而典型山区林区的养殖业进一步发展的空间相对较小(25.2万头的盈余量),应该适度控制和调整养殖业的发展.     

脱水污泥颗粒等温干燥特性实验研究

采用3种不同类型的脱水污泥(消化污泥、曝气生物滤池污泥和剩余污泥),制成3种粒度的污泥颗粒,并分别在65、85、105和125 ℃条件下进行恒温干燥实验.结果表明,减小污泥颗粒和增大干燥温度均可缩短污泥完全干燥时间,提高污泥的最大干燥速率;消化污泥干燥速率最高,曝气生物滤池污泥次之,剩余污泥的干燥速率最低.通过扫描电镜分析干燥后的污泥可知,消化污泥表面非常粗糙,结构比较松散;剩余污泥表面相对比较光滑,结构密实;而曝气生物滤池污泥表面比较粗糙,结构比较致密.污泥表面的粗糙程度与等温干燥速率有密切关系.     

崇明岛风景旅游区空气负离子监测评价方案研究

崇明岛作为上海市的未来生态岛屿,至今尚未开展过系统的空气负离子研究。依据该县相关规划,结合区域植被、地貌、人为影响等因素,在东滩国家级自然保护区、东平国家森林公园、前卫村、明珠湖和西沙湿地5个监测区域共选定了18个空气质量监测点进行研究。按崇明风景旅游区的具体情况,对国内外7种空气负离子监测评价方法进行了比较,最终确定选用安培空气质量评价系数、森林空气离子评价系数、空气负离子系数评价法、轻重离子比评价法来对该岛的空气质量进行评价。最后还对相关负离子监测仪器进行了分析及建议。     

坡度对跨座式单轨隧道临界风速的影响

为研究不同坡度隧道在大功率火源情况下的烟气运动,采用1∶20的缩尺隧道模型,通过试验对不同坡度情况下(-6%,-3%,0%,3%,6%)的大火源功率火灾(20,50 MW)时的隧道纵向通风临界风速进行研究。结果表明:0%坡度时,20 MW和50 MW的临界风速相差不大;有坡度时,逆坡送风的临界风速大于顺坡送风的临界风速。根据试验结果拟合得出大火源功率(20,50 MW)条件下坡度为-6%至6%时的临界风速与坡度的关系,并对前人提出的坡度与临界风速的关系式进行修正。     

熵权法在铀矿井下空气环境安全评价中的应用研究

为科学合理地评价铀矿井下空气环境质量,通过对广东某铀矿及辽宁某铀矿井下空气环境的调查,分析了铀矿井下空气环境的特点及其危害,确定氡、氡子体、铀矿尘、CO、NO2及矿井气候6个指标为影响铀矿井下空气环境质量的主要因素,依此建立铀矿井下空气环境安全评价指标体系.采用模糊综合评价法建立了铀矿井下空气环境安全评价模型,并采用熵权法客观赋权的方式确定各评价指标权重,避免了评价过程中人为主观因素的影响,从而得到比较客观的评价结果.以南方某铀矿井为例,运用建立的评价模型对其井下采场、巷道掘进、天井掘进3个工作面空气环境质量进行安全评价.结果 表明,采场工作面空气环境质量为良好,巷道掘进工作面和天井掘进工作面空气环境质量为中等.其评价结论可为企业优化井下工作场所空气环境质量提供参考.