New insights into FeS/persulfate system for tetracycline elimination: Iron valence, homogeneous-heterogeneous reactions and degradation pathways

In this study, complete tetracycline（TTC） and above 50% of total organic carbon（TOC） were removed by Fe S/PS after 30 min under optimized conditions. Although free radicals and high-valent iron ions were identified to generate in the process, the apparent similarity between intermediate products of Fe S/PS, Fe/PS, and UV/PS systems demonstrated that the degradation of TTC was due to sulfate radicals(SO₄^·-) and hydroxyl radicals（ ·OH）. Based on the reaction between free radi...     

温度-高度试验箱温场状态分析

温度-高度试验箱是人工模拟温度-高度综合环境因素的试验装置,其所提供的环境参数及其变化过程必须满足受试品的试验技术条件.了解温度-高度综合温场变化状态,是保证试验达到考核要求的前提.工程技术人员在进行产品的热设计时,需关注温度-高度综合温场变化的特殊性.     

Vegetation dynamics in succession process from Stipa bungeana to Artemisia ordosica in the Ordos Plateau北大核心CSCD

Shrub invasion has a serious effect on the structure and function of grassland ecosystems and understanding vegetation dynamics is of great significance to control shrub invasion and recover shrub invaded grassland. In the Ordos Plateau, we selected representative communities in transition process from Stipa bungeana to Artemisia ordosica. By sampling, cutting, and root-drilling methods, plant coverage, density, biomass, litter, root, and species diversity of different communities were investigated and analyzed. The results showed the following: (1) the succession process had six vegetation types, S. bungeana communities, S. bungeana + Cleistogenes squarrosa communities, S. bungeana + Artemisia ordosica communities, A. ordosica + C. squarrosa communities, A. ordosica + Lespedeza davurica communities, and A. ordosica communities. (2) The community coverage decreased initially, and then increased. Whereas, the total density decreased initially, then increased, and then decreased. The aboveground, underground, and total biomasses, and the dry weight of litter showed an increasing trend. (3) The coverage, density, and biomass of S. bungeana decreased gradually, whereas A. ordosica showed an opposite trend. (4) With the increase in soil depth, the dry weight of root showed a decreasing trend. The roots were mainly distributed in the 0-30 cm soil layer. At VI stage, the root distribution of Artemisia community initially increased, and then decreased, and the root depth reached 80-90 cm. (5) The species richness, Simpson, Shannon-Winner, and Pielou evenness indexes initially increased, and then decreased. In summary, shrub encroachment is severe in the Ordos Plateau. Although the community coverage, biomass, and biodiversity during the moderate shrub encroachment stage were high, the shrub-invaded grassland should be restored to S. bungeana grassland due to the decreased grazing value of grassland after shrub invasion. Keywords. © 2018 Science Press. All rights reserved.     

氟对中华圆田螺肝胰脏抗氧化酶活性和MDA含量的影响

选取中华圆田螺为受试动物,探究氟对其肝胰脏抗氧化酶SOD、GSH、POD活性和丙二醛(MDA)含量的影响。结果显示,在不同浓度水氟环境条件下(0、40、80、160 mg·L~(-1))连续暴露10 d、20 d和30 d时,与对照组相比,中华圆田螺肝胰脏SOD活性在暴露前20 d,中低浓度组活性被诱导升高,高浓度组受抑制降低。暴露30 d时,中低浓度组活性降低,高浓度组逐渐升高。MDA含量在暴露前20 d时,中低浓度组活性整体被诱导升高,高浓度组受抑制降低。暴露30 d时,MDA含量受到显著抑制均低于对照组。GSH活性以诱导为主均高于对照组,POD活性在10 d时均低于对照组,而在20 d时被诱导升高且均高于对照组,30 d时中高浓度以抑制为主。上述研究结果为水质污染控制及生态风险评价提供了基础数据。     

不同水稻品种对镉积累的差异及其与镉亚细胞分布的关系

采用土培试验,以籽粒Cd低积累水稻品种(越冬稻和R1088)和籽粒Cd高积累水稻品种(IR34582和太粳558)为试验材料,研究成熟期水稻在Cd0(不加Cd)、Cd5(5 mg·kg~(-1))和Cd25(25 mg·kg~(-1))胁迫下,Cd在水稻各组织中的积累差异及其与Cd亚细胞分布的关系,为培育Cd低积累水稻品种和水稻安全生产提供科学依据。结果表明:(1) Cd胁迫下,约65%～83%的Cd积累于根系,低积累品种根系Cd含量显著高于高积累品种,而地上部却相反;(2)高积累品种往地上部转运Cd的效率以及地上部各组织往籽粒转运Cd的效率均显著高于低积累品种;(3) Cd胁迫下,低积累品种根中细胞壁(F1)、细胞器(F2)、细胞膜(F3)和可溶部分(F4)中Cd含量显著高于高积累品种,而茎、叶鞘和叶中却相反;(4)低积累品种根和茎中F1中Cd分配比例均显著高于高积累品种,而F4中Cd分配比例却相反;在叶鞘和叶中,F1、F4中Cd分配比例在不同品种之间无显著差异。(5) Cd胁迫下,TF_(根-茎)和TF_(茎-糙米)均与F1中Cd分配比例成显著负相关关系,而与F4中Cd分配比例成显著正相关关系。综上,高积累品种往地上部转运Cd的能力强于低积累品种;低积累品种根和茎中细胞壁限制了Cd的迁移;而高积累品种根和茎中可溶部分在Cd从根部向上以及从茎向籽粒转运过程中起着重要作用。     

基于高通量分析的长江干流重庆段重点关注污染物筛选

应用高通量分析方法对长江干流重庆段11个断面水体中的潜在污染物进行了分析,共筛查到230种污染物。结合重庆市化学品生产使用统计结果,应用综合评分法对潜在污染物进行了评分和排序,筛选出33种流域重点关注污染物,包括农药、工业用品(邻苯二甲酸酯类、酚类雌激素、有机溶剂)及个人护理品(抗氧化剂、合成麝香、紫外吸收剂)等。结果表明,基于高通量分析方法和综合评分法可成功识别和筛选流域内重点关注污染物,为流域管理提供科学依据。     

不同约束方式下钢筋混凝土短柱火灾后(下)力学性能的试验研究

为研究钢筋混凝土短柱在相邻构件约束条件下,并经荷载和火灾共同作用后的力学性能,开展了18根受不同约束方式作用的钢筋混凝土短柱火灾后(下)力学性能的试验研究。获得了火灾后(下)钢筋混凝土短柱的剩余承载力、剩余轴压刚度、荷载—轴向变形关系曲线,分析讨论了约束方式、标准升温时间及荷载比等对火灾后钢筋混凝土短柱力学性能的影响。研究结果表明,火灾下和火灾后钢筋混凝土柱试件的破坏模式类似,但后者的混凝土表面裂纹以及剥落较前者严重;不论是火灾下还是火灾后,恒刚度约束的试件破坏较恒荷载约束严重;且恒荷载约束条件下得到的试件耐火极限大于恒刚度约束条件下得到的耐火极限。     

胭脂鱼仔幼鱼的摄食习性及其生长

胭脂鱼幼鱼具有明显的昼夜摄食节律.仔鱼以适口的浮游动物为食,并随着口位下移,转而摄食底层生物.文中分别对140日幼鱼的日龄与全长、全长与体重以及全长和全长/体高的关系作了曲线回归方程,反映了幼鱼的生长特点.本工作为增殖该种珍稀鱼类资源提供了基础资料,并对其观赏价值进行了评价.     

Evidence of Al-Cr interactions affecting Cr-leaching from waste incineration ashes

Leaching tests on flue gas ashes from waste incineration showed low leaching of Cr from ashes that under moist anaerobic conditions also produced hydrogen gas. In some cases, also the redox levels (aerobic/anaerobic conditions) during the leaching test affected Cr leaching. Aerobic ashes tested in an open batch leaching test leached Cr up to 2-3 orders of magnitude more than the ashes kept moist under anaerobic conditions and tested in a closed leaching test. Model experiments showed that metallic Al could reduce Cr and at the same time produce H(2). The hydrogen gas per se could not reduce Cr. Laboratory experiments with ashes provided evidence that metallic Al, present naturally in the ashes or amended, could reduce Cr under moist anaerobic, but not under aerobic storage. Significant Cr reduction was linked to, but not caused by hydrogen formation. The reduced Cr seemed to be partially reoxidizable upon aeration or drying. The observations presented provide a basis for understanding the complexity of Cr leaching from waste incineration ashes, as for example, why some chemical stabilization methods increase Cr leaching, and point out the need for standardizing leaching test conditions with respect to Cr.     

浅谈废水生物处理的新进展

综述了生物脱氮除磷的反应机理和几种主要工艺,并做出了相应的分析评价,指出在废水生化处理中生物脱氮除磷因工艺简单、处理能力强、运行方式灵活等优点得到国内外的普遍高度重视,并成为当前重点研究的课题。