污水处理厂脱氮效果及相关参数的分析

通过对长沙某污水处理厂进行24 h水质、水量的监测,分析了其Carrousel氧化沟处理污水的特点.从脱氮的原理出发,结合流速、溶解氧等运行参数的考察,发现造成脱氮效果不好的主要原因是沟内缺少厌氧区段,提出改进措施,从宏观改善流体的流动人手,以达到调控溶解氧传递的目的,既而促进微观的硝化与反硝化反应,提高污水处理效果.     

活性氧化铝和其他滤料除微量磷效果比较

试验研究了活性氧化铝和其他7种滤料在饮用水工艺中对微量磷和浊度的去除效果,并进行了比较和分析.结果表明,活性氧化铝对溶解性总磷的去除效果明显要优于其他7种滤料,对颗粒态总磷的去除效果和其他7种滤料相比没有优势,活性氧化铝对总磷的去除优势主要在于对溶解性总磷的吸附性能,对于浊度的去除效果和其他7种滤料相近.     

含钒石煤生产五氧化二钒污染治理

介绍用含钒石煤生产五氧化二钒的原理和低污染生产工艺。论述了五氧化二钒生产中废水、废气、废渣、噪声的产生及其废水、废气、噪声的治理方法与效果。并介绍了废渣的处置与综合利用技术及五氧化二钒生产可能带来的放射性影响及防护措施。     

中国北方地区年降水与气温关系及其时空变异性

降水与气温之间的不同关系类型对植被、水资源、生态环境等有着不同的影响,全面揭示大范围多气候类型区关系类型及其时空变异性和影响成为重要研究内容.文章以范围较广、涵盖气候类型较多的中国北方地区为研究区,利用研究区及其周边的357个高密度气象站点1951—2016年年降水量、气温数据,采用中心聚类等方法,定性、定量揭示了中国...     

How does the spatial structure of habitat loss affect the eco-epidemic dynamics?

Habitat loss is considered as one of the primary causes of species extinction, especially for a species that also suffers from an epidemic disease. Little attention has been paid to the combined effect of habitat loss and epidemic transmission on the species spatiotemporal dynamics. Here, a spatial model of the parasite–host/prey–predator eco-epidemiological system with habitat loss was studied. Habitat patches in the model, instead of undergoing a random loss, were spatially clustered by different degrees. Not only the quantity of habitat loss but also its clustering degree was shown to affect the equilibrium of the system. The infection rate and the probability of successful predation were keys to determine the spatial patterns of species. The epidemic disease is more likely to break out if only a small amount of suitable patches were lost. Counter-intuitively, infected preys are more sensitive to habitat loss than predators if the lost patches are highly clustered. This result is new to eco-epidemiology and implies a possibility of using spatial arrangement of suitable (or unsuitable) patches to control the spread of epidemics in the ecological system.     

金属氧化物对CO还原NO反应的催化作用

采用固定床流动反应器,研究ＣｕＯ、Ｃｒ２Ｏ３、ＭｎＯ２、Ｆｅ２Ｏ３、Ｎｉ２Ｏ３等单元金属氧化物及它们形成的复合氧化物对ＣＯ还原ＮＯ反应的催化活性。结果表明,在５００℃８００ｍｌ／ｍ＾３ＮＯ－０．２％ＣＯ－２．０％ＣＯ２－Ｎ２气氛中ＣＯ还原ＮＯ的能力很小,稳定还原率仅为１．５０％。     

Field‐scale uranium (VI) bioimmobilization monitored by lipid biomarkers and 13C‐acetate incorporation

At the Old Rifle uranium mill‐tailing site in eastern Colorado, a test of subsurface amendment with acetate to stimulate the reductive immobilization of uranium was monitored by using lipid biomarker analysis and incorporation of ¹³C‐labeled acetate into lipid biomarkers. Both sediment and groundwater samples were analyzed. Within 7 days of acetate addition, groundwater microbial biomass increased by a factor of 5, and remained higher than control values in most samples for the 28 days sampled. At 29 days after the beginning of acetate amendment, 4 of 12 sediment samples had microbial biomass greater than the 95 percent confidence interval of controls. The mole percents of the phospholipid fatty acids 16:1ω7c and 16:1ω5c increased over control values upon acetate amendment, and incorporated high levels of ¹³C from labeled acetate in groundwater and sediment samples. 16:1ω7c is a biomarker for Geobacter, and evidence is provided that 16:1ω5c represents an unidentified iron‐reducing bacterium, probably a member of the Desulfobulbaceae. Biomarkers for organisms other than iron‐reducing bacteria, iso‐ and anteiso‐branched fatty acids and 18:1ω9c, decreased upon acetate amendment, and had their highest stable isotope incorporation at least 4 days after labeled acetate amendment ended, evidence for carbon‐sharing between iron‐reducers and other microorganisms. © 2011 Wiley Periodicals, Inc.     

Mg/Al水滑石对水中痕量邻苯二甲酸酯的吸附动力学和热力学

研究了Mg／A1水滑石对水中痕量邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二（2一乙基己基）酯（DEHP）和邻苯二甲酸二辛酯（DnOP）的吸附动力学和热力学特性。结果表明,在所研究的浓度范围内,3种邻苯二甲酸酯的吸附动力学曲线均符合准二级速率方程,DMP、DEHP和DnOP分别在600、200和200min基本达到吸附平衡;3种邻苯二甲酸酯的吸附等温线基本符合Langmuir和Freundlich吸附等温方程;在283～308K范围,pH=6．36,3种邻苯二甲酸酯初始浓度均为50μg／L时,吸附过程△H为负值且绝对值为5～12kJ／mol,表明吸附为放热过程,以表面物理吸附为主,邻苯二甲酸酯在Mg／Al水滑石上的吸附是色散力、诱导力、取向力和氢键力等多种作用力协同作用的结果。     

Al-SiO2介孔材料吸附电解锰废水中的锰、铬离子

以不同n (Al )1 n (SiO 2 )的Al -SiO 2 介孔材料为吸附剂处理电解锰废水,并利用中卜组合设计法研究电解锰废水中锰离子与铬离子(包括铬(!和铬(")的相互作用对材料吸附性能的影响.实验结果表明:以n (Al )1 n (SiO 2 )为1:1 的Al -SiO 2 介孔材料为吸附剂,当吸附剂加入量...     

Developmental toxicity of cypermethrin in embryo-larval stages of zebrafish

Cypermethrin, a type II pyrethroid insecticide, is widely used throughout the world in agriculture, forestry, horticulture and homes. Though the neurotoxicity of cypermethrin has been thoroughly studied in adult rodents, little is so far available regarding the developmental toxicity of cypermethrin to fish in early life stages. To explore the potential developmental toxicity of cypermethrin, 4-h post-fertilization (hpf) zebrafish embryos were exposed to various concentrations of cypermethrin (0, 25, 50, 100, 200 and 400 μg L⁻¹) until 96 h. Among a suite of morphological abnormalities, the unique phenotype curvature was observed at concentrations as low as 25 μg L⁻¹. Studies revealed that 400 μg L⁻¹ cypermethrin significantly increased malondialdehyde production. In addition, activity of antioxidative enzymes including superoxide dismutase and catalase were significantly induced in zebrafish larvae in a concentration-dependent manner. To further investigate the toxic effects of cypermethrin on fish, acridine orange (AO) staining was performed at 400 μg L⁻¹ cypermethrin and the result showed notable signs of apoptosis mainly in the nervous system. Cypermethrin also down-regulated ogg1 and increased p53 gene expression as well as the caspase-3 activity. Our results demonstrate that cypermethrin was able to induce oxidative stress and produce apoptosis through the involvement of caspases in zebrafish embryos. In this study, we investigated the developmental toxicity of cypermethrin using zebrafish embryos, which could be helpful in fully understanding the potential mechanisms of cypermethrin exposure during embryogenesis and also suggested that zebrafish could serve as an ideal model for studying developmental toxicity of environmental contaminants.