锰矿区土-水界面污染流中重金属来源分析

基于对湘潭锰矿红旗矿区土-水界面重金属污染流的采样分析,通过相关性和主成分分析法,研究了锰矿区土-水界面重金属污染流中的锰、镍、铜、锌、镉、铅重金属的来源以及同源性。结果表明:6种重金属的差异性、离散程度、变异性较大;锰—镍、锰—锌、锰—镉、锰—铅、镍—锌、铜—锌、铜—铅、锌—镉、锌—铅、铅—镉呈极显著正相关,镍与锰以外的其他重金属相关性都较低;3个主成分的贡献率分别为58.300%、16.628%、11.115%,累积贡献率达到了81.543%,并且6种重金属在主成分1的载荷非常高。结合矿区的周边环境和自身特点,表明6种重金属的主要共同来源为矿区内的矿业活动,并且工业活动、交通运输、农业活动等也对矿区造成了一定程度的重金属污染。     

发酵类抗生素废水处理工艺及运行效果

介绍了内蒙古某抗生素废水处理厂的处理工艺流程、处理单元类型及其详细设计参数,通过对该污水处理厂半年内运行效果的调研,分析评价该污水处理系统的处理效果及出水指标;该水厂工艺流程对COD、TOC、氨氮、总氮、总磷、BOD和急性毒性的平均去除率分别为96.52%、95.83%、50.24%、55.20%、62.05%、98.52%和99.14%,COD、氨氮、总氮、总磷出水水质分别为477、438、556.7和7.69 mg/L,达到排放到城区下水道要求,园区内所有废水汇集到园区污水处理厂进行集中深度处理达标后排放水体。通过对该水厂工艺的介绍和水质分析,为我国抗生素生产企业面临的废水处理工艺类型选择及工程改造升级提供一定参考。     

基于层次分析法的未确知测度理论泥石流危险性评价

将未确知测度理论与层次分析方法相结合用于评价泥石流危险性。根据泥石流危险性的影响因素和等级划分标准,选取泥石流规模、泥石流发生频率、流域面积、主沟长度、最大相对高差、流域切割密度、主沟床弯曲系数、泥砂补给长度比、24小时最大降雨量、人口密度等10个指标作为泥石流危险评价因子,利用未确知测度理论建立泥石流危险性评价指标的未确知测度函数,通过层次分析方法确定各评价指标的权重,依据置信度识别准则对泥石流危险性进行评价,并结合实例进行了对比分析。研究结果表明,基于层次分析方法的未确知测度理论的评价方法评价过程合理、置信度高、结果可靠,为泥石流危险性评价提供了一种新的方法     

不同场地条件下水下隧道周围土体位移变化的数值分析

以拟建的哈尔滨松花江隧道为背景,考虑土体—衬砌的材料非线性特性和相互作用,按平面应变假定,建立在不同场地条件下的若干接近实际的有限元计算模型,应用有限元计算软件ANSYS进行数值分析,得出不同场地条件下隧道周围土体位移的分布规律,遴选出了影响水下隧道周围土体变形的部分关键因素,为合理确定隧道覆土层安全厚度提供了一定的理论依据。     

Exposure to moderate concentrations of tropospheric ozone impairs tree stomatal response to carbon dioxide

With rising concentrations of both atmospheric carbon dioxide (CO₂) and tropospheric ozone (O₃), it is important to better understand the interacting effects of these two trace gases on plant physiology affecting land-atmosphere gas exchange. We investigated the effect of growth under elevated CO₂ and O₃, singly and in combination, on the primary short-term stomatal response to CO₂ concentration in paper birch at the Aspen FACE experiment. Leaves from trees grown in elevated CO₂ and/or O₃ exhibited weaker short-term responses of stomatal conductance to both an increase and a decrease in CO₂ concentration from current ambient level. The impairement of the stomatal CO₂ response by O₃ most likely developed progressively over the growing season as assessed by sap flux measurements. Our results suggest that expectations of plant water-savings and reduced stomatal air pollution uptake under rising atmospheric CO₂ may not hold for northern hardwood forests under concurrently rising tropospheric O₃.     

Engineered nanomaterials in rivers--exposure scenarios for Switzerland at high spatial and temporal resolution

Probabilistic material flow analysis and graph theory were combined to calculate predicted environmental concentrations (PECs) of engineered nanomaterials (ENMs) in Swiss rivers: 543 river sections were used to assess the geographical variability of nano-TiO₂, nano-ZnO and nano-Ag, and flow measurements over a 20-year period at 21 locations served to evaluate temporal variation. A conservative scenario assuming no ENM removal and an optimistic scenario covering complete ENM transformation/deposition were considered. ENM concentrations varied by a factor 5 due to uncertain ENM emissions (15%-85% quantiles of ENM emissions) and up to a factor of 10 due to temporal river flow variations (15%-85% quantiles of flow). The results indicate highly variable local PECs and a location- and time-dependent risk evaluation. Nano-TiO₂ median PECs ranged from 11 to 1′623 ng L⁻¹ (conservative scenario) and from 2 to 1′618 ng L⁻¹ (optimistic scenario). The equivalent values for nano-ZnO and nano-Ag were by factors of 14 and 240 smaller.     

Mass flows of perfluorinated compounds (PFCs) in central wastewater treatment plants of industrial zones in Thailand

Perfluorinated compounds (PFCs) are fully fluorinated organic compounds, which have been used in many industrial processes and have been detected in wastewater and sludge from municipal wastewater treatment plants (WWTPs) around the world. This study focused on the occurrences of PFCs and PFCs mass flows in the industrial wastewater treatment plants, which reported to be the important sources of PFCs. Surveys were conducted in central wastewater treatment plant in two industrial zones in Thailand. Samples were collected from influent, aeration tank, secondary clarifier effluent, effluent and sludge. The major purpose of this field study was to identify PFCs occurrences and mass flow during industrial WWTP. Solid-phase extraction (SPE) coupled with HPLC-ESI-MS/MS were used for the analysis. Total 10 PFCs including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluoropropanoic acid (PFPA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluoronanoic acid (PFNA), perfluordecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA) were measured to identify their occurrences. PFCs were detected in both liquid and solid phase in most samples. The exceptionally high level of PFCs was detected in the treatment plant of IZ1 and IZ2 ranging between 662-847 ng L⁻¹ and 674-1383 ng L⁻¹, respectively, which greater than PFCs found in most domestic wastewater. Due to PFCs non-biodegradable property, both WWTPs were found ineffective in removing PFCs using activated sludge processes. Bio-accumulation in sludge could be the major removal mechanism of PFCs in the process. The increasing amount of PFCs after activated sludge processes were identified which could be due to the degradation of PFCs precursors. PFCs concentration found in the effluent were very high comparing to those in river water of the area. Industrial activity could be the one of major sources of PFCs contamination in the water environment.     

Virtual phosphorus ore requirement of Japanese economy

Phosphorus is indispensable for agricultural production. Hence, the consumption of imported food indirectly implies the import of phosphorus resources. The global consumption of agricultural products depends on a small number of ore-producing countries. For sustainable management of phosphorus resources, the global supply and demand network should be clarified. In this study, we propose the virtual phosphorus ore requirement as a new indicator of the direct and indirect phosphorus requirements for our society. The virtual phosphorus ore requirement indicates the direct and indirect demands for phosphorus ore transformed into agricultural products and fertilizer. In this study, the virtual phosphorus ore requirement was evaluated for the Japanese economy in 2005. Importantly, the results show that our society requires twice as much phosphorus ore as the domestic demand for fertilizer production. The phosphorus contained in “eaten” agricultural products was only 12% of virtual phosphorus ore requirement.     

壁面粗糙度对旋风分离器内流场影响的数值模拟

利用计算流体动力学软件FLUENT6.2.16对壁面粗糙度不同的旋风分离器内流场进行了数值模拟,得到了切向速度、轴向速度、径向速度和静压力分布规律。旋风分离器内的切向速度随着壁面粗糙度的增大而明显减小;轴向速度没有明显的规律性变化,只在上部筒体涡核区轴向速度增加,削弱了涡核区滞留现象;在流场大部分区域径向速度随粗糙度的...     

垂直流人工湿地水力学特性研究

通过示踪剂实验从停留时间分布（RTD）曲线及其统计特征值等方面对垂直流人工湿地的水力学特性进行了定性和定量的分析。研究表明水流在垂直流人工湿地中的流动是一种非理想的不均匀流动,存在一定的死区和水流的扩散;垂直流人工湿地较大的死区率与其表面布水的不均匀性有关,这也可能是其死区率大于表流人工湿地的最主要的原因。实验还表明,进水流量对垂直流人工湿地停留时间分布影响较大,随着进水流量的增加,平均停留时间减小,但标准平均停留时间增大,死区率减小;当进水流量为15L／h（水力负荷为620mm／d）时,水流在湿地中的散度最大,水流更接近全混流,不利于污染物的降解。