Degradation of 2,4-dichlorophenoxyacetic acid in water by ozone-hydrogen peroxide process

IntroductionAt present, several types of organic pollutantsreferred to as environmental endocrine disruptors(ED) have been suggested to be associated withabnormal sexual development (Hu, 2000). It wasreported that the ED led to the decline of reproductive…     

沼渣协同硫酸亚铁修复Cr(Ⅵ)污染土壤

通过稳定化实验、连续提取实验及植物毒性实验,研究了沼渣对硫酸亚铁稳定化Cr （Ⅵ）污染土壤的促进效果与机制.结果表明,沼渣协同硫酸亚铁对土壤中Cr （VI）有良好的稳定化效果.最佳的修复条件为：n（Fe）/n（Cr）=3∶1,含水率为35%,沼渣投加量为4.5%,反应时间为12 d,此时Cr （VI）稳定化效率为99.85%,残余六价铬含量为1.49 mg·kg^-1,满足《土壤环境质量建设用地土壤污染风险管控标准》（GB 36600—2018）第二类用地筛选值5.7 mg·kg^-1的限值要求.由连续提取实验结果可知,沼渣+硫酸亚铁稳定化处理后酸溶态铬含量显著降低,而可还原态、可氧化态和残渣态铬含量明显增加.风险分析进一步表明,沼渣+硫酸亚铁稳定化处理后铬的风险等级由非常高风险降至低风险.植物毒性分析可知,沼渣+硫酸亚铁稳定化处理植物毒性显著降低.微生物多样性和群落结构分析可知,沼渣+硫酸亚铁稳定化处理后土壤中细菌群落的丰度和多样性均明显增加.     

多段进水A/O生物膜工艺运行性能的研究

为提高多段进水A/O生物膜工艺的脱氮效率,按照进入各缺氧池的COD量与硝态氮量的比值相同,且等于一最优比值的原则进行流量分配,按照容积负荷相等的原则设计各反应单元,对多段进水A/O生物膜工艺的流量分配和反应单元容积分配同时进行优化,并采用三段进水A/O生物膜反应器试验了等流量分配模式下运行和优化模式下运行的出水水质的差异.试验结果表明,当多段进水A/O生物膜工艺在两种模式下采用相同参数运行时,优化模式下总氮(TN)去除率明显高于等流量模式,其分别为88.8%和80.3%.优化模式与等流量分配模式对COD和总凯氏氮的去除率差别不大(均可达到97%和98%以上).采用该优化设计方法可以显著提高该工艺的TN去除效率.     

我国削减并逐步替代全氟辛烷磺酸盐(PFOS)的策略与建议

全氟辛烷磺酸盐(PFOS)具有低表面张力、良好的热稳定性和化学稳定性等特性,作为含氟表面活性剂被广泛应用于卫生、消防与电镀等工业领域.但是,PFOS具有高持久稳定性,会在环境、人体与动物组织中富集,因此2009年《斯德哥尔摩公约》将PFOS列为新增POPs受控物质.目前,我国还在生产和使用PFOS,如何对其进行有效控制,削减并逐渐替代PFOS及其衍生物,是我国面临的巨大挑战.在介绍了PFOS的生产与应用现状基础上,结合其替代技术,提出了削减和逐步替代PFOS的策略.     

上海沿海防护林空气负离子水平测定

空气负离子被誉为“空气维生素”,是衡量空气质量的重要指标。为了探讨城市防护林改善人居环境的效应,选择上海南汇地区的沿海防护林作为研究对象,对空气负离子水平进行了分析测定。结果表明,不同土地利用方式、林分内不同空间空气负离子分布呈现显著差异;负离子水平随林分树种不同而变化。不同土地利用方式下负离子浓度表现为：林地〉小区〉公园〉村落〉农用地;空间分布上,距离林带10m的浓度达到603个／cm^3,比30m距离和50m距离分别多13个／cm^3和61个／cm^3;距地面不同高度测定,地表处的负离子浓度最高,为2298个／cm^3;不同林分中,中山杉（Ascendens mltcronatttm）林地     

气固两相流下球阀磨损特性研究

旋塞球阀是钻柱内防喷系统中的关键设备,在气固两相流下球阀易受磨损而失效,并造成严重的井喷事故。为此,将计算流体动力学理论与冲蚀磨损理论相结合,运用FLUENT软件对球阀壁面在气固两相流下的磨损分布情况进行研究,并进一步分析了球阀结构参数对于球阀壁面磨损的影响规律。结果表明:当气固两相流流经球阀时,固体颗粒会与气流分离,并在壁面上产生三处磨损集中区;随着球阀开度的减小,球阀壁面磨损量会急剧增大,且阀球内通道壁面上的磨损集中区由块状逐步转化为带状,而球阀出口处的磨损集中区则会逐渐向下移动;球阀流道直径的减小也会使得壁面磨损量增加,但磨损集中区的分布基本不变。研究结果可为进一步优化球阀流道结构以减轻其壁面磨损提供理论依据。     

黄土高原近30年植被变化特征及其气候驱动

The use of Normalized difference vegetation index (NDVI) data acquired with multiple satellite sensors has become a necessity in research fields such as agriculture, Land-Use and Land-Cover Change (LUCC) and changes in the natural environment. In this paper, vegetation 10-day composite (VGT-S10) NDVI data with a 1 km×1 km resolution, covering the period from April 1982 to December 2011 and Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modelling and Mapping Studies (GIMMS) NDVI data with a 8 km×8 km resolution, covering the period from April 1998 to December 2006 were used. The VGT NDVI covering the period from 2007 to 2011 was converted to the GIMMS NDVI for the same period. The vegetation trend during 1982 to 2011 was calculated using the extended NDVI data set. Climate change has a large impact on the vegetation dynamics. A series of statistical analyses were employed to demonstrate the relationship between NDVI and meteorological data during 1982 to 2005. A multiple correlation analysis was applied to validate the association between the two climatic factors and monthly maximum NDVI (MNDVI). The partial correlation coefficient of MNDVI and each climate factor were calculated respectively to describe the singular influence of each meteorological variable. The results indicated that temperature made a significant positive influence on vegetation growth in the whole Loess Plateau. Precipitation is the most important climatic factor that closely correlates with MNDVI, particularly in arid and semi-arid environments. However, in some wet regions, precipitation is not a limiting factor on vegetation growth.     

Degradation of pyrene by immobilized microorganisms in saline-alkaline soil

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB+MF was increased by 161.7% (P < 0.05), 60.1% (P < 0.05) and 59.6% (P < 0.05) after 30 days, respectively, when compared with free F2, MF and MB+MF. Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline-alkaline soil, as the interspace of the carrier material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAH-degradation ability in saline-alkaline soil.     

河南马沟洞石笋记录的早中全新世气候和环境变化

基于河南省禹州市马沟洞2支石笋(MG-1与MG-40)24个~(230)Th年龄和1988个氧同位素数据,建立了研究区13.1—4.9 ka BP分辨率为2—14 a的石笋氧同位素时间序列。马沟洞石笋δ~(18)O的时间序列揭示季风降水在11.2—9.1 ka BP时段在波动中逐渐增加,9.1—4.9 ka BP季风降水显著波动但无明显长期趋势变化。YD事件、9.3 ka事件、8.2 ka事件记录与其他石笋δ~(18)O记录的一致性揭示末次冰消期—早全新世百年—千年尺度气候突变事件的大范围存在和共同的驱动因子。马沟洞全新世大暖期的δ~(18)O记录中检测出的13个数十年尺度的弱季风事件进一步证实全新世大暖期气候的不稳定性。与大气⊿~(14)C记录、NGRIP冰芯δ~(18)O记录的对比及周期分析揭示,太阳活动引起的太阳辐射变化和北半球高纬气候状况共同影响着亚洲季风的变化,ENSO活动及气候系统内部的相互作用也对东亚夏季风降水产生重要的影响。