Research progress of nitrous oxide reductase gene (nosZII) and its relationship with the environment北大核心CSCD

The greenhouse effect has become increasingly serious globally. Nitrous oxide (N2O) is both the major ozone depleting substance and a potent greenhouse gas having a global warming potential 298 times that of CO2, and the N2O concentration is still increasing at an annual rate of about 0.8 × 10-9. Nitrous oxide reductase (N2OR) can reduce N2O to N2, and until recently, the nosZ gene was the only gene known to be able to encode N2OR. Besides the well-known nosZI, a new lineage of the N2O-reductase (nosZ clade II), which is abundant and widespread in soils, has been identified. In this paper, the main characters of nosZII-containing microbial communities and the related working mechanisms are summarized. In addition to the main differences between nosZI and nosZII, the important environmental factors that regulate the composition, abundance, and expression of nosZII-containing communities are also discussed in this paper. Studies have shown that nosZII communities are distributed among a diverse range of bacterial and archaeal phyla, such as Epsilon-proteobacteria, Bacteroidetes, and Aquificae. Interestingly, most of the nosZII microbes lack a nitrite reductase encoding gene (nirS or nirK) and are therefore unable to denitrify, indicating the importance of these communities as N2O sinks. Soil properties such as texture, pH, C/ N ratio, temperature, and lake physical gradient could regulate nosZII microbe abundance and diversity, and the pH and C/ N ratio may be the most important influencing factors. Studies on the ecological function of nosZII microbes have advanced considerably with the development of molecular biology technology. However, further studies on the community structure of nosZII microbes, the influencing factors of nosZII microbe abundance and diversity, and characteristics of nosZII strains with strong N2O reducing ability are needed. We hope to provide a theoretical basis that can be used to facilitate N2O reduction and relieve the greenhouse gas problem. © 2018 Science Press. All rights reserved.     

Modelling of turbulent dispersion for numerical simulation of wind-driven rain on bridges

Wind-driven rain (WDR) is responsible for many potential negative effects on bridges, such as structural cracking, aggregate erosion, steel corrosion and storm water management problems and so on. Hence, accurate evaluations of the WDR effects on bridges are essential to provide solutions for preventing material degradation and improving durability capability of bridges. However, in most previous WDR numerical studies, the turbulent dispersion of raindrops was neglected. In this paper, the turbulent dispersion is integrated into Eulerian multiphase model to investigate the WDR effects on a bridge with rectangular cross-section. Especially, the influences of the turbulent dispersion are discussed in detail by comparing the WDR simulation results for the cases with and without consideration of the turbulent dispersion in terms of WDR flow fields, volume fraction, specific catch ratio, catch ratio, rain loads and aerostatic force coefficients. The results indicate that the turbulent dispersion for a certain range of raindrop size is needed to be taken into account for obtaining accurate WDR simulation results for bridges.     

Effects of ambient temperature on regulated gaseous and particulate emissions from gasoline-, E10- and M15-fueled vehicles

• Emissions from two sedans were tested with gasoline, E10 and M15 at 30°C and -7°C. • As the temperature decreased, the PM, PN and BC emissions increased with all fuels. • Particulate emissions with E10 and M15 were more sensitive to the temperature. • The PN and BC generated during cold start-up dominated those over the WLTC. Ambient temperature has substantial impacts on vehicle emissions, but the impacts may differ between traditional and alcohol gasolines. The objective of this study was to investigate the effects of temperature on gaseous and particulate emissions with both traditional and alcohol gasoline. Regulated gaseous, particle mass (PM), particle number (PN) and black carbon (BC) emissions from typical passenger vehicles were separately quantified with gasoline, E10 (10% ethanol and 90% gasoline by volume) and M15 (15% methanol and 85% gasoline by volume) at both 30°C and -7°C. The particulate emissions with all fuels increased significantly with decreased temperature. The PM emissions with E10 were only 48.0%–50.7% of those with gasoline at 30°C but increased to 59.2%-79.4% at -7°C. The PM emissions with M15 were comparable to those with gasoline at 30°C, but at -7°C, the average PM emissions were higher than those with gasoline. The variation trend of PN emissions was similar to that of PM emissions with changes in the fuel and temperature. At 30°C, the BC emissions were lower with E10 and M15 than with gasoline in most cases, but E10 and M15 might emit more BC than gasoline at -7°C, especially M15. The results of the transient PN and BC emission rates show that particulate emissions were dominated mainly by those emitted during the cold-start moment. Overall, the particulate emissions with E10 and M15 were more easily affected by ambient temperature, and the advantages of E10 and M15 in controlling particulate emissions declined as the ambient temperature decreased.     

江苏省夏季典型传输通道城市臭氧污染成因及VOCs污染特征

在2020年8月11—15日的一次典型光化学污染过程中,在江苏省东南沿江传输通道城市同步开展了大气挥发性有机物(VOCs)的加密观测,使用基于观测的OBM模型诊断了典型城市臭氧(O_(3))生成机制,并分析其污染成因,梳理了通道城市VOCs化学组成特征、O_(3)生成潜势(OFPs)及污染日与清洁日的差异。结果表明,监测期间大部分城市呈现首尾(8月11和15日)O_(3)超标、中间达标的特征,气象要素影响较小,与前体物关联更为密切。沿江通道城市污染日VOCs总体积分数为15.79×10^(-9)~54.9×10^(-9),均值为31.88×10^(-9),是清洁日城市总体积分数均值(18.08×10^(-9))的1.76倍。南京、镇江、扬州等城市O_(3)生成总体处于VOCs控制区,泰州8月11日处于NOx控制区。各城市VOCs化学组成均以烷烃为主(平均占比31.8%),其次是含氧挥发性有机物(OVOCs)(26.5%)和卤代烃(19.1%),其他组分占比较低。污染日烷烃、炔烃和芳香烃的体积分数升幅显著高于其他类组分,尤其是芳香烃,增幅为45.1%~296.3%。各城市OFPs中,优势组分均为芳香烃和烯烃,其中乙烯、丙烯、甲苯、乙苯和间对二甲苯等物种质量浓度在污染日上升显著,对O_(3)生成影响较大。     

障碍物对油气-空气混合气体泄压爆炸火焰传播特性影响

为了研究障碍物对油气泄压爆炸火焰传播特性的影响规律,进行了不同数量障碍物工况下的对比实验,并利用纹影仪和高速摄影仪记录了火焰传播过程,针对障碍物对火焰形态、火焰锋面位置及火焰传播速度的影响规律进行了研究,结果表明:圆柱体障碍物会导致油气泄压爆炸火焰形态产生褶皱和弯曲变形,诱导层流火焰向湍流火焰转变,加速火焰的传播,对油气泄压爆炸火焰的初始传播形态有显著影响;随着障碍物数量的增多,火焰锋面传播距离点火端的最大距离增大,但到达最远距离的时间减少;障碍物能够增强火焰的传播速度,尤其对障碍物下游火焰影响最为显著,随着障碍物数量的增多,火焰传播的最大速度也随之增大,但达到最大火焰传播速度的时间却随之减少;障碍物的存在增大了油气泄压爆炸过程外部爆炸压力,并且随着障碍物数量的增多,外部爆炸压力峰值增长幅度增大。     

TiO2投加量及其表面载银量对光催化降解Aro-clor1260的影响

在紫外灯照射下,催化剂TiO₂的投入量及其表面载银量对光催化降解Aroclor1260有显著的影响.但TiO₂的投入量并不与Aroclor1260的降解速率成正比关系,而是有一个最佳投入量,在本文的实验条件下,这个最佳值为60mg(3g/L).TiO2的表面载银量越多,Aroclor1260的降解速率也越大,而且浓度相对较高的PCB单体化合物的降解速率大于浓度相对较低的PCB单体化合物的降解速率.对于多数PCB单体化合物而言,TiO₂的催化活性随其表面载银量的增加而增强.     

五氯苯酚对淡水双壳类背角无齿蚌 ρ 型谷胱甘肽S-转移酶表达的影响

谷胱甘肽S-转移酶(GST)在机体抗击氧化应激中发挥重要作用。前期研究表明,五氯苯酚(PCP)处理对背角无齿蚌(Anodonta woodiana)具有显著的氧化应激和急性毒性效应。为了探讨PCP慢性毒性效应,本研究将背角无齿蚌随机分为对照组和PCP处理组,PCP处理组和对照组分别用13.9 mg·L~(-1)和相同体积二甲亚砜处理;同时,克隆出ρ型谷胱甘肽S-转移酶并命名为ρ-GST,分析PCP对ρ-GST表达的影响。ρ-GST全长c DNA包含一个57 bp的5’端非编码区,291 bp的3’端非编码区和678 bp的开放阅读框。ρ-GST在背角无齿蚌斧足、外套膜、闭壳肌、心脏、肝胰腺、血淋巴和鳃中广泛表达。与对照组相比,PCP处理后肝胰腺ρ-GST mRNA在第1天、第3天和第15天分别增加18.18%、82.88%(P<0.05)和2.43倍(P<0.01); PCP处理后鳃中ρ-GST mRNA水平增加1.44倍以上(P<0.05); PCP处理后血淋巴中ρ-GST mRNA水平显著上调。背角无齿蚌ρ-GST表达水平上调有助于对抗PCP处理所产生的应激效应,提高动物环境耐受能力。     

淡水双壳类背角无齿蚌AwHSP70基因克隆及多溴联苯醚-47对其表达的影响

热休克蛋白(HSP)参与蛋白质折叠、细胞膜转位和错误折叠蛋白质降解等过程,提高动物对环境的应激能力和适应能力。前期研究表明,多溴联苯醚-47(PBDE-47)对背角无齿蚌具有显著的氧化应激和急性毒性效应,为探讨PBDE-47慢性毒性效应;将背角无齿蚌随机分为对照组和PBDE-47处理组,处理组用3.36μg·L~(-1)浓度的PBDE-47进行处理,对照组用相同体积的二甲亚砜进行处理;克隆出AwHSP70基因,分析PBDE-47对AwHSP70表达的影响。结果显示,AwHSP70具有HSP70家族的标签序列,广泛分布于斧足、鳃、肝胰脏、闭壳肌、心脏、血淋巴和外套膜。PBDE-47处理可导致肝胰脏、鳃和血细胞中AwHSP70 mRNA水平显著升高。与对照组相比,PBDE-47处理组肝胰脏中AwHSP70 mRNA水平在1～15 d内增加2. 79倍(P<0.01)以上;鳃中AwHSP70 mRNA水平增加3.06倍(P<0.01)以上;血淋巴中AwHSP70表达增加1.81倍(P<0.05)以上。背角无齿蚌上调AwHSP70表达有助于增强动物对PBDE-47的耐受能力。     

东中西部区域农业差异及其特征分析

我国东中西部区域农业发展水平的差异较大，认识这种差异的特征对于制定区域农业协调发展的战略决策具有重要意义。本文选择有关区域经济、社会、资源与环境方面的17项指标，采用主成分分析方法，对我国区域农业发展差异的现状进行了分析。结果表明，目前，东中西部农业发展的整体差异仍然很大，主要表现为人均农业产值和人均乡镇企业产值差异较大。而且，从1980～1995年农民人均纯收入的吉尼系数一直呈现增大趋势，说明区域差异呈持续扩大的态势。到1998年人均农业产值的吉尼系数高达0．43，已经高于国际警戒水平。对近10年东中西部乡镇企业产值变化的分析说明，自从实施西部开发战略以来，东中西部乡镇企业产值的比值已经由16：5．6：1．0变为4．5：2．1：1．0。显然西部开发促进了西部农业经济的发展，缩小了区域农业发展水平的差异。     

室内安全卫生现状及对策

室内安全卫生状况越来越受到人们的关注。美国环保署组织的调查表明 ,室内环境问题已成为影响人类健康的 4个主要环境因素之一 ,4 0 %的发病率是由室内环境差引起。 2 0世纪 90年代以来 ,欧美等国家在室内环境污染因素的识别、检测、评价、控制管理方面进行了系统的研究 ,笔者结合中国实际情况 ,综述以上 4个方面的系统研究 ,提出了我国在技术上和管理上提高室内安全卫生质量状况的初步设想