Composition, source, mass closure of PM2:5 aerosols for four forests in eastern China

PM2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve (CB), Dongping National Forest Park in Chongming Island (CM), Dinghu Mountain Nature Reserve (DH), Jianfengling Nature Reserve in Hainan Island (HN). The mass concentrations of PM2.5, organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) as well as concentrations of ten inorganic ions (F-, Cl-, NO3-, SO42-, C2O42-, NH4+, Na+, K+, Ca2+, Mg2+) were determined. Aerosol chemical mass closures were achieved. The 24-hr average concentrations of PM2.5 were 38.8, 89.2, 30.4, 18 μg/m3 at CB, CM, DH and HN, respectively. Organic matter and EC accounted for 21%-33% and 1.3%-2.3% of PM2.5 mass, respectively. The sum of three dominant secondary ions (SO42-, NO3-, NH4+) accounted for 44%, 50%, 45% and 16% of local PM2.5 mass at CB, CM, DH and HN, respectively. WSOC comprised 35%-65% of OC. The sources of PM2.5 include especially important regional anthropogenic pollutions at Chinese forest areas.     

高铝粉煤灰综合利用节能减排对比分析

高铝粉煤灰是近年来在我国内蒙古中西部地区发现的一种粉煤灰新类型,特别是鄂尔多斯高原东北缘的准格尔煤田,煤中富铝矿物燃烧后产生的粉煤灰中氧化铝含量达到50％左右,相当于我国中级品位铝土矿中氧化铝的含量。本文首先介绍了我国铝土矿的资源现状,然后叙述了目前国内外利用高铝粉煤灰提取氧化铝主要生产工艺及工艺特点,并对不同工艺的能源消耗和节能减排进行了对比分析。     

填料对曝气生物滤池影响的概述

曝气生物滤池因为其优越的自身条件,逐渐成为世界各国首选的处理各种污水的处理装置。而填料作为曝气生物滤池最关键影响因素引起广泛关注。文章简单介绍了填料的研究进展,对填料上生物膜的形成以及其填料净化机理等方面进行了研究;填料的选择是滤池设计和出水水质的关键因素。填料的类型、粒径、密度、高度对曝气生物滤池的效能有重要影响。尽管目前填料种类繁多,但由于曝气生物滤池除磷能力较弱,希望开发更多新型曝气生物滤池填料类型,更好地满足各种类型废水的处理。     

乙蒜素乳油在黄瓜和土壤中的残留消解动态

采用田间试验,对乙蒜素乳油在长沙、广州、山东、北京四地的黄瓜及土壤中的残留进行了研究,结果表明乙蒜素在黄瓜中的消解速度较快,乙蒜素在黄瓜中半衰期分别为广州3．47d,长沙1．37d,山东2．10d,北京3．18d;乙蒜素在土壤中半衰期分别为广州3．34d,长沙2．46d,山东2．60d,北京2．89d;41％乙蒜素乳油兑水稀释1500倍（乙蒜素浓度为33．75mg·L^-1）,使用2次,末次施药7d后,乙蒜素在未检出-0．011mg·kg^-1,在土壤中为未检出。该药属于易降解农药（T1/2〈30d）,按推荐剂量使用是安全的。     

塔玛亚历山大藻对文蛤呼吸和排泄的影响

水温20℃下,设置(0、0.1、0.5、1.0、2.0、4.0) ×103/mL六个藻类浓度组,以静水方法研究了塔玛亚历山大藻对文蛤呼吸和排泄的影响.结果表明:当塔玛亚历山大藻浓度为1.0 ×103/mL时,文蛤的耗氧率和排磷率最大,其最大值分别为2.76 ×10-3 /h和0.339 μmol/(g·h);其排氨率在藻浓度为0.5 ×103 /mL时达到最大值5.71 μmol/(g·h).耗氧率与排氨率的比值(O/N)显示在较低塔玛亚历山大藻浓度(≤0.5 ×103 /mL)时,文蛤由蛋白质和脂肪提供机体能量,较高藻浓度(≥1.0 ×103 /mL)时则由脂肪和碳水化合物提供机体代谢所需能量.     

Experimental investigation of the machining induced residual stress tensor under mechanical loading

Residual stress induced by machining is complex and difficult to predict, since it involves mechanical loads, temperature gradients or phase transformation in the generation mechanism. In this work, an experiment with a statistical design for the residual stress tensor was performed to investigate the residual stress profile on a machined surface. In order to understand the generation mechanism of residual stress in machining, three variables and workpiece materials were carefully selected to focus on the mechanical loads and avoid the temperature gradients and phase transformation on the machined surface. The mechanical loads considered here included the chip formation force at the primary shear zone and the plowing force at the tool tip–workpiece contact. Depths of cut and rake angles were selected to alter the chip formation force, and the tool tip radius was designed to emphasize the plowing effect. The workpiece material was aluminum 3003. The experimental results showed that the chip formation force provides basic shapes of the residual stress profile for a machined surface. It decides the depth of the peak residual stress below the surface. However, the plowing force was the dominating effect on the surface residual stress, causing high stresses on the surface. The plowing force can shift the surface stress from tensile to compressive. Additionally, the measured stress tensor proved that in-plane shear stress exists for the machined surface.     

基于ANSYS技术的尿素高压气提塔管束剩余寿命的评估

以乌鲁木齐石化公司化肥厂尿素气提塔管束为例,运用ANSYS有限元分析技术,将设备剩余寿命评估技术引入到管板类高压设备剩余寿命的评估中,建立了一套完整的管板类高压设备剩余寿命评估体系与流程,给出了尿素气提塔管束剩余寿命的简化计算评估方法和有限元的精细计算评估方法,并根据剩余寿命评估实例对评估体系进行了分析和说明.     

沈阳市新城子铬渣堆存区土壤铬污染分布及形态分析

采用Tessier A连续提取法,研究分析了沈阳市新城子铬渣堆存区土壤中重金属铬的污染分布和迁移转化规律,土壤中重金属铬的5种形态分布,主要以残渣态和碳酸盐结合态为主,分别占总量的49.74%和21.4%,而有机结合态含量最低,占总铬含量的6.25%。不同的功能区域铬的形态分布有所不同。总体的分布特征是残渣态>碳酸盐结合态>交换态>铁猛氧化态>有机态。     

基于EPANET-MSX的多组分给水管网水质模型的开发与应用

基于EPANET-MSX工具包开发了机制性的多组分给水管网水质模型,模型将管段概化为管壁、生物膜、液膜和液相4个组成部分.模拟过程包括基质利用和微生物生长、微生物衰减和死亡、溶解性物质的液膜传质、不溶性物质的吸附和脱落、余氯与有机物的氧化和卤代反应以及管壁腐蚀消耗余氯等.模拟变量共15个,包括生物膜和液相中各7个变量,即溶解性有机物、不溶性有机物、氨氮、余氯、异养菌、自养菌和惰性颗粒,以及管壁生物膜厚度.利用管段模拟实验数据进行模型验证,模型对余氯和浊度的模拟精度分别为0.1 mg/L和0.3 NTU.案例研究的模拟结果合理地反映了给水管网中余氯和浊度的动态变化特征,而同时考虑水厂出水水质可变性和参数不确定性的Monte Carlo模拟则可用于评价案例给水管网的水质超标风险.     

典型电子垃圾拆解区大气中多溴联苯醚的污染

分别在典型电子垃圾拆解区(E)和其上风向参考点(S)采集了大气颗粒相和气相样品.以研究该区域大气中PBDEs的浓度水平、污染特征和气/固分布特点.分析过程中运用气相色谱.质谱联用仪,负化学离子源(GC-NCI-MS)检测了11种PBDEs结果表明,电子垃圾拆解造成r比较严蘑的PBDEs污染,三溴-十溴联苯醚的浓度范围为51.1～2 685 pg.m-3,(平均值830Pg.m-3),而对照区由于制衣行业的影响也造成了一定程度的PBDEs污染,三溴～十溴联苯醚的浓度范围为1.00-98.9Pg.m-3(平均值28.7 Pg.m-3).在气/固分布的研究中发现,不同的PBDEs在气相和颗粒相的分布比例相差很大,从低溴至高溴PBDEs在气相中的比例呈降低趋势,而在颗粒相中的比例呈上升趋势.电子垃圾拆解区以五溴.联苯醚污染为主,占∑11PBDEs总量的54.3%;而十溴-联苯醚污染次之,占∑11PBDEs总最的23.8%,该污染特征进一步证实了该地区电子垃圾的来源,不仅来自亚洲国家,而且还来自欧美等国家.