絮团尺寸对全尾砂絮凝沉降效果的影响研究*

为研究絮团尺寸对全尾砂絮凝沉降效果的影响,采用正交实验和图像颗粒分析相结合的方法,进行多因素耦合条件下全尾砂絮凝沉降实验,基于Giddings函数的沉降速度模型,提出全尾砂絮团图像颗粒分析,探究各时段絮团尺寸的变化规律。研究结果表明:当尾砂浆浓度为15%、絮凝剂溶液浓度为0.25%、絮凝剂单耗为20 g/t,pH值为10时,絮凝沉降效果最佳,最大沉降速度达13.12 mm/s;随着沉降时间的增加,沉降速度随絮团直径、长径比减小而减小,随圆形度增大而减小。研究结果可为实际生产中控制全尾砂絮凝沉降参数、提高沉降速率提供参考。     

A Method for Evaluating the Morphological Diversity of Strawberry Leaves in Natural Populations

A method for comparing polymorphic characters is proposed. As an example, the morphological diversity of strawberry leaves is evaluated. Initially, the factors determining leaf shape and the main directions of its variation are identified. These directions are used as coordinates outlining the space of possible realizations of the character. The polymorphic sets of real leaves from individual populations differ in being located in different parts of this space.     

絮体老化与调节对回流进水及混凝的影响机制

为探索絮体老化与pH值调节对回流进水颗粒组成及混凝的影响,采用激光粒度仪进行了絮体粒径分析并通过Al （OH）₃胶体（Al-gel）的老化实验探究了老化与pH值调节对絮体形态及性质的内在影响机制.结果表明,原水颗粒物粒径呈现单峰分布,絮体回流进水颗粒物粒径呈现双峰分布,并且回流进水颗粒d₅₀随着絮体老化时间的增加而减小;由于絮体回流提高了颗粒物与混凝剂接触机率和碰撞效率,因此加快了絮体的生长;絮体在pH=5的环境下老化12h后进行回流混凝的絮体粒径生长速率最高（1.16 μm/s）并且生成的絮体具有较大的分形维数（2.35）.Al-gel的老化实验结果表明,絮体老化过程会涉及羟桥反应和结晶反应并导致絮体的表面活性基团数量减少,从而不利于与原水颗粒物的相互作用.pH值调节对絮体产生不同的影响,pH=5的条件下进行老化会加速絮体的羟桥反应和结晶反应,而pH=9的条件下进行老化则会涉及溶解-沉淀-结晶反应.     

颗粒物对混凝过程及超滤膜污染的影响

以nm-SiO₂和μm-SiO₂体系为研究对象,使用3种不同Al形态的混凝剂（AlCl₃、Al₁₃和Al₃₀）进行混凝-超滤实验,考察不同pH值下SiO₂去除率、出水余Al及混凝预处理对膜通量的影响,借助马尔文激光粒度仪、SEM、BET和AFM表征絮体性质及在超滤膜表面的分布和作用力.结果表明,nm-SiO₂体系中SiO₂去除率均低于μm-SiO₂体系,在纳米颗粒物体系中投加混凝剂后膜通量从0.68分别提升至0.96（AlCl₃）、0.86（Al₁₃）和0.87（Al₃₀）,微米颗粒物体系中投加3种混凝剂后膜通量从0.79提升至0.80~0.84.微米级颗粒物是颗粒间的碰撞,纳米级颗粒物主要以团聚态的形式碰撞.低聚态铝（Al_a）和颗粒物形成絮体的粒径均大于150μm,体系zeta电位为负与膜表面产生斥力;在中性条件下Al₁₃与颗粒物形成絮体的强度因子远高于AlCl₃和Al₃₀,中聚态铝（Al_b）将膜孔内部较小颗粒物堵塞形成的不可逆膜污染转移成膜孔表面的可逆膜污染;高聚态铝（Al_c）具有较强吸附架桥和网捕卷扫能力,无定形、不规则的团聚态小颗粒在这一过程中形成较大絮体缓解膜污染.     

Hydrologic and Morphologic Variability of Streams With Different Cranberry Agriculture Histories,Southern New Jersey,United States1

Procopio, Nicholas A., 2010. Hydrologic and Morphologic Variability of Streams With Different Cranberry Agriculture Histories, Southern New Jersey, United States. Journal of the American Water Resources Association (JAWRA) 46(3):527-540. DOI: 10.1111/j.1752-1688.2010.00432.x Abstract: The creation of reservoirs and the modification of stream channels are common practices used to facilitate the efficient production of cranberries. The potential impacts to hydrologic and geomorphic aspects of streamflow and channel structure have not been adequately assessed. In this study, the streamflow regime of 12 streams and the channel morphologies of 11 streams were compared for study sites in the Pinelands region of New Jersey with upstream active-cranberry bogs, upstream abandoned-cranberry bogs, and basins with no apparent agricultural history. Flow regime metrics included measures of low-flow, median-flow, and bankfull discharge, two measures of streamflow variability (spread and a modified Richards-Baker Flashiness index), and the frequency of overbank flooding. Stream-channel morphology metrics included average bank slope, average bankfull width, average bankfull depth, average bankfull width-to-depth ratio, and average bankfull area. No significant differences between stream types were apparent for any of the metrics. Basin-area normalized streamflow values of all 12 study sites were highly correlated to each other. Significant relationships existed between some of the flow-regime and channel-morphology metrics. Due to the lack of significant differences between stream types, it appears that neither historic nor current cranberry agricultural practices considerably influence flow regimes or the channel morphology of streams in the New Jersey Pinelands.     

Influence of foliar morphology and crown geometry on insecticide deposition and dissipation following an aerial spray over a mixed forest

Abstract

Deposition and dissipation of aerially sprayed phosphamidon insecticide over a mixed forest consisting of different species of coniferous and deciduous trees were studied. The data showed that the chemical deposited more and dissipated slower from deciduous foliage than from conifer needles. Differences in deposits and persistence were also found within each of the two foliar types. Leaf shape and orientation, crown geometry and foliar morphology appear to have played a role. No correlation was found between initial deposit levels and cuticular wax content of different foliar species. A controlled laboratory study showed that surface area/mass ratio played a more important role on initial deposits than pubescence/serrations present on foliar surfaces.     

上流式厌氧污泥床反应器处理饮料废水

通过监测西安可口可乐饮料有限公司污水处理站的上流式厌氧污泥床(UASB)反应器,探讨饮料废水厌氧处理过程中COD去除率、沼气组分、氢分压、出水挥发性脂肪酸、产甲烷活性以及污泥形态。结果表明,UASB反应器对饮料废水中的COD去除率达到84.55%,产生的沼气中甲烷组分含量高达74.5%。反应器内的氢分压仅2.5 Pa,为水解发酵和产氢产乙酸过程创造了良好的条件。UASB反应器中污泥具有较高的产甲烷活性,以乙酸、丙酸和丁酸为基质时,最大比产甲烷活性分别为407.14、331.74和241.27 m L CH4/(g VSS·d)。UASB反应器中的污泥形态主要为絮状,甲烷菌中的优势菌为甲烷丝菌,同时存在少量甲烷杆菌。针对该厂UASB反应器中污泥的现状,提出了影响颗粒化的因素和控制措施,为后期的运行和管理提供了参考依据。     

Modeling Streams and Hydrogeomorphic Attributes in Oregon From Digital and Field Data1

Abstract: Managers, regulators, and researchers of aquatic ecosystems are increasingly pressed to consider large areas. However, accurate stream maps with geo‐referenced attributes are uncommon over relevant spatial extents. Field inventories provide high‐quality data, particularly for habitat characteristics at fine spatial resolutions (e.g., large wood), but are costly and so cover relatively small areas. Recent availability of regional digital data and Geographic Information Systems software has advanced capabilities to delineate stream networks and estimate coarse‐resolution hydrogeomorphic attributes (e.g., gradient). A spatially comprehensive coverage results, but types of modeled outputs may be limited and their accuracy is typically unknown. Capitalizing on strengths in both field and regional digital data, we modeled a synthetic stream network and a variety of hydrogeomorphic attributes for the Oregon Coastal Province. The synthetic network, encompassing 96,000 km of stream, was derived from digital elevation data. We used high‐resolution but spatially restricted data from field inventories and streamflow gauges to evaluate, calibrate, and interpret hydrogeomorphic attributes modeled from digital elevation and precipitation data. The attributes we chose to model (drainage area, mean annual precipitation, mean annual flow, probability of perennial flow, channel gradient, active‐channel width and depth, valley‐floor width, valley‐width index, and valley constraint) have demonstrated value for stream research and management. For most of these attributes, field‐measured, and modeled values were highly correlated, yielding confidence in the modeled outputs. The modeled stream network and attributes have been used for a variety of purposes, including mapping riparian areas, identifying headwater streams likely to transport debris flows, and characterizing the potential of streams to provide high‐quality habitat for salmonids. Our framework and models can be adapted and applied to areas where the necessary field and digital data exist or can be obtained.     

不同锰处理对镉胁迫下2种油菜重金属累积和根系形态的影响

采用水培试验,研究Cd胁迫(10μmol·L~(-1))条件下,不同浓度Mn(0,0.1,1,10,100μmol·L~(-1))处理对2种镉累积能力不同的油菜生物量、Cd和Mn含量以及根系形态参数的影响。结果表明,与正常营养处理Mn1相比,缺Mn和Mn过量处理显著降低2种油菜的地上部和镉低积累油菜"华骏"的根部生物量,而对普通油菜"寒绿"的根部生物量没有显著影响。与Mn1处理相比,缺Mn处理下2种油菜的Cd累积总量和"华骏"地上部Cd含量显著降低;Mn过量处理下2种油菜根部和地上部Cd含量均呈升高趋势,2种油菜的Cd累积总量无显著变化或显著降低。随Mn处理浓度升高,2种油菜地上部和根部Mn含量显著升高,缺Mn处理下2种油菜根部的Mn含量低于Mn缺乏的临界值。与Mn1处理相比,缺Mn处理下"华骏"的根长、表面积、体积、平均直径和根尖数显著降低;Mn过量处理下"寒绿"的根长以及"华骏"的根系表面积、体积显著降低;缺Mn处理下2种油菜细根表面积所占的比例增加,粗根表面积比例降低;Mn过量时,"寒绿"的粗根表面积比例增加,细根比例降低,而"华骏"则相反。总的来看,缺Mn处理影响油菜根系和地上部生长,减少地上部Cd含量和植株Cd累积总量;Mn过量处理下油菜生长也受到抑制,但是油菜地上部和根部Cd含量有所升高;2种油菜的根系形态学参数在不同Mn处理下变化规律不同,表现出不同的响应策略。     

焊料在NaCl溶液中重金属元素的浸出行为

电子垃圾填埋时重金属元素的浸出会造成环境和地下水的污染,进而危害人类的健康。文章以Sn-0.75Cu、Sn-3.5Ag-0.75Cu和Sn-37Pb焊料合金及接头作为对象,研究了它们在3.5%NaCl溶液中重金属元素的浸出行为。结果表明,3种焊料合金浸出后Sn的浸出量差别不大,而3种钎焊接头Sn的浸出量却高出焊料合金中浸出量的1个数量级,并且无铅钎焊接头中Sn的浸出量高于Sn-37Pb钎焊接头;焊料合金中Ag、Cu的浸出量较少,Pb的浸出量较高,而钎焊接头中Ag、Cu及Pb的浸出量均高于焊料合金。焊料合金在NaCl溶液中浸出后表面生成的腐蚀产物较少,而钎焊接头浸出后表面生成的腐蚀产物却很多,其产物主要是由SnCl2、Sn(4OH)6Cl2和PbC(lOH)相组成。