江苏南京地区蜻蜓目(Odonata)昆虫区系及多样性分析

2005～2008年对江苏南京地区的蜻蜓资源进行了调查，共发现蜻蜓目昆虫45种，隶属于8科29属。其区系组成的特点是：东洋成分占明显优势，有13种，约占总数的2889%；古北区的种类相对较少，只有5种，约占总数的1111%。研究分析了7个样地蜻蜓的物种丰富度多样性指数(〖WTBX〗H′)、均匀度指数(J)、优势度指数(D)和相似性系数(Cs〖WTBZ〗)。结果发现：蜻蜓物种丰富度由大到小的顺序为紫金山(30)=老山(30)>将军山(24)>江心洲(19)>方山(18)>东庐山(13)>金牛湖(9)；各样地的多样性指数排序为将军山(2.9298)>紫金山(2.9150)>老山(2.7258)>方山(2.6574)>江心洲(2.5478)>东庐山(1.9025)>金牛湖(1.6700)。其中，方山与东庐山的相似性系数最大(0.7742)，金牛湖分别与紫金山和老山的相似性系数最小(0.4103)。     

微孔分布器对光催化臭氧氧化反应器传质的影响

为了开发高效的光催化臭氧氧化反应器,以不同孔径钛微孔气体分布器对臭氧气液传质性能进行了研究.考察了表观气速和表观液速对液相总传质系数的变化影响规律,获得了液相总传质系数与表观气速的关联公式和微孔板孔径与表观气速对液相总传质系数的经验关联公式.利用无因次吸收数对微孔分布器的性能进行了分析,得到不同表观气速下微孔分布器的性...     

Mercury species of sediment and fish in freshwater fish ponds around the Pearl River Delta, PR China: human health risk assessment

This study investigated total mercury (THg) and methylmercury (MeHg) concentrations in five species of freshwater fish and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The concentrations of THg and MeHg in fish pond surface sediments were 33.1-386 ng g(-1) dry wt and 0.18-1.25 ng g(-1) dry wt, respectively. The age of ponds affected the surface sediment MeHg concentration. The vertical distribution of MeHg in sediment cores showed that MeHg concentrations decreased with increasing depth in the top 10 cm. In addition, a significant correlation was observed between %MeHg and DNA from Desulfovibrionacaea or Desulfobulbus (p<0.05) in sediment cores. Concentrations of THg and MeHg in fish muscles ranged from 7.43-76.7 to 5.93-76.1 ng g(-1) wet wt, respectively, with significant linear relationships (r=0.97, p<0.01, n=122) observed between THg and MeHg levels in fish. A significant correlation between THg concentrations in fish (herbivorous: r=0.71, p<0.05, n=7; carnivorous: r=0.77, p<0.05, n=11) and corresponding sediments was also obtained. Risk assessment indicated that the consumption of largemouth bass and mandarin fish would result in higher estimated daily intakes (EDIs) of MeHg than reference dose (RfD) for both adults and children.     

分层式潜流人工湿地水力学特性数值模拟与分析

人工湿地水力学特征对其污染物去除过程有重要影响.采用计算流体力学软件FLUENT中的多孔介质模型对分层式潜流人工湿地内部的流场进行模拟,并分析了不同进出口位置对湿地水力学行为的影响.模拟结果表明,分层式潜流人工湿地基质层内部速度分布的差异较大,水流多从进口端的左半部汇人下部砾石层以大于3.69×10-4m/s的速度出流...     

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO₂ remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L⁻¹ nano-TiO₂, the (LC₅₀) of Cu²⁺ concentration observed to kill half the population, decreased from 111 μg L⁻¹ to 42 μg L⁻¹. Correspondingly, the level of metallothionein decreased from 135 μg g⁻¹ wet weight to 99 μg g⁻¹ wet weight at a Cu²⁺ level of 100 μg L⁻¹. The copper was found to be adsorbed onto the nano-TiO₂, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO₂ may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.     

Photodegradation of Benthiocarb

The photodegradation of ¹⁴C-benthiocarb in water, on a glass surface, on soil and silica gel TLC plates was studied. the study was designed to obtain some information of its dissipation and photodegradation under various laboratory conditions. Benthiocarb degrades readily when exposed to either sunlight or UV light (254 nm). However, it is degraded much faster by UV light than by sunlight. Also, benthiocarb decomposes faster in water or on a glass surface or silica gel surface than on a soil surface. the half-life of benthiocarb exposed to UV light was: 1 hr on glass surface; 1.5 hrs in water; 2 hrs on silica gel TLC plate; 20 hrs on soil TLC plate. Benthiocarb in water, and exposed to sunlight, had a half-life of approximately 3 days. the following major photodegradation products were identified: 4-chlorobenzyl alcohol; 4-chlorobenzaldehyde; 4-chlorobenzoic acid.     

便携式ＧＣ-ＭＳ测定空气中有毒物质的应用

文章介绍了便携式气相色谱-质谱联用仪(Gas Chromatograph-Mass Spectrometer,GC-MS)的结构原理,结合应急监测的需要,说明了仪器性能参数与分析操作模式,探讨了标准曲线的建立与验证。通过仪器的实际应用,指出该仪器能够解决应急监测中目前存在的对有机污染物难以快速定性、定量的问题。利用捕集浓缩器富集待测定空气中挥发性有机化合物(VOCs),可迅速判断出气体样品中的挥发性有机化合物组分,给出定量测定结果。并根据日常使用情况,总结了便携式GC-MS性能特点。     

Ti-SnO_2电解快速去除熄焦循环水中COD

以Ti-SnO2电极作为阴阳极,利用电解池对焦化厂熄焦循环水COD进行去除。极板间距为1 cm,6个极片组成电解池,处理熄焦循环水。实验结果表明:废水被稀释1倍时,污染物的浓度有利于COD的去除;最佳去除条件是电解电压为11 V,p H值为6;当电解时间为0.5 h时,废水的COD由230 mg/L降低到138 mg/L,满足《炼焦化学工业污染物排放标准》中规定的焦化生产废水经处理后用于熄焦时对COD的要求;电解时间增加到2 h,废水的COD由230 mg/L降低到66 mg/L,去除率达到80%。     

新东方教学管理应用于高职英语教学的研究

高职教育是我国高等教育体系中不可或缺的部分,其中英语教学面临学生基础差,缺乏学习动机和兴趣且存在两级分化,课堂秩序混乱的局面。教师在教学管理中缺乏方法,缺乏成就感,教改和创新动力不足,且高职院校师资构成不合理,教师缺乏提升进修渠道。以新东方为代表的民办教育中,学生学习兴趣浓厚,出勤率高,课堂秩序井然。教师提升手段较多,激励机制较为完整,师资构成更为合理,教学效率高。通过高职和新东方教学管理的对比,探索高职英语教学的解困之道,以推进高职英语教学向更好的方向发展。