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501.
pH和负压对生活垃圾焚烧厂渗沥液蒸发处理的影响 总被引:3,自引:1,他引:2
生活垃圾焚烧厂贮坑渗沥液含有弱电解质类的挥发性污染物,pH和压强是影响其蒸发过程中气液相分布的主要因素,实验研究了蒸发操作压强及渗沥液初始pH对蒸发冷凝液中污染物分配的影响.结果表明,操作压强16~39kPa对冷凝液的组成基本没有影响;而pH的变化则改变了挥发性弱电解质类污染物在渗沥液中的存在形态,进而显著地改变了其在冷凝液中的分配情况.当渗沥液的初始pH为5时,冷凝液主要成份为挥发性有机酸和低碳醇类物质,不含氨氮;pH>10时,冷凝液中挥发性有机酸减少,氨氮增加.渗沥液原液经一级蒸发可显著改善其可处理性. 相似文献
502.
基于2001~2018年长三角地区生物医药产业合作申请专利数据,采用社会网络分析方法,对长三角地区城市间创新网络的空间结构进行探究,并借助面板负二项固定效应模型对网络结构的影响机制进行分析。研究发现:长三角生物医药产业创新网络呈现简单到复杂、低级到高级的演化过程;在地理空间上呈现以上海为中心的放射状结构,创新网络密度呈现东高西低的态势,创新节点和创新联系主要集中于长三角东侧。长三角地区城市间生物医药产业创新网络的构建,不仅受到其自身经济发展水平、产业结构、外商投资和地理邻近性等因素的影响,也会受到城市内部创新网络密度的影响,且城市在全国创新网络中的地位也会对区域内城市间创新合作的构建产生正向效应。 相似文献
503.
504.
To better understand the feeding and reproductive ecology of euphausiids (krill) in different ocean environments, lipid classes
and individual lipid components of four different species of euphausiids from Northeast Pacific (temperate species) and Southern
Ocean (Antarctic species) were analyzed in animals from multiple life stages and seasons. The dominant krill species in the
Northeast Pacific Euphausia pacifica and Thysanoessa spinifera, were compared to the two major Antarctic species, Euphausia superba and E. crystallorophias. Analysis comprised total lipid and lipid classes together with individual fatty acid and sterol composition in adults, juveniles,
and larvae. Antarctic krill had much higher lipid content than their temperate relatives (10–50 and 5–20% of dry mass for
Antarctic and temperate species, respectively) with significant seasonal variations observed. Phospholipids were the dominant
lipid class in both temperate krill species, while neutral storage lipids (wax esters and triacylglycerols for E. crystallorophias and E. superba, respectively) were the major lipid class in Antarctic krill and accounted for up to 40% of the total lipid content. Important fatty acids, specifically 16:0, 18:1ω9, 20:5ω3, and 22:6ω3, were detected in all four krill species, with minor
differences between species and seasons. Detailed lipid profiles suggest that krill alter their lipid composition with life
stage and season. In particular, larval Antarctic krill appear to utilize alternate food resources (i.e., sea-ice associated
organisms) during austral winter in contrast to juveniles and adults (i.e., seston and copepods). Lipid dynamics in krill
among krill in both systems appear closely linked to their life cycle and environmental conditions including food availability,
and can provide a more complete comparative ecology of euphausiids in these environmentally distinct systems. 相似文献
505.
Feng Zhao Xu Zhan Hai Xu Guangwei Zhu Wei Zou Mengyuan Zhu Lijuan Kang Yulong Guo Xingchen Zhao Zicong Wang Wei Tang 《环境科学学报(英文版)》2022,34(1):229-239
Eutrophication and harmful cyanobacterial blooms threaten water resources all over the world. There is a great controversy about controlling only phosphorus or controlling both nitrogen and phosphorus in the management of lake eutrophication. The primary argument against the dual nutrients control of eutrophication is that nitrogen fixation can compensate the nitrogen deficits. Thus, it is of great necessary to study the factors that can significantly affect the nitrogen fixation. Due to the dif... 相似文献
506.
The generation of reactive species in an aqueous goethite suspension, under room light and aeration conditions, was investigated using the electron paramagnetic resonance (EPR) technique employing spin trap agents. The trap reagents, including 5,5-dimethylpyrroline N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP), were used for the detection of OH radicals (OH) and singlet oxygen (1O2), respectively. On the addition of DMPO to the goethite suspended solution, a DMPO-OH adduct was formed, which was not decreased, even in the presence of the OH scavenger, mannitol. This result implied a false positive interpretation from the DMPO-OH EPR signal. In the presence of TEMP reagent, a TEMP-O signal was detected, which was completely inhibited in the presence of the singlet oxygen scavenger, sodium azide. With both DMPO-OH and TEMP-O radicals in the presence and absence of radical scavengers, singlet oxygen was observed to be the key species formed in the room-light sensitized goethite suspension. In the goethite/H2O2 system; however, both OH and singlet oxygen were generated, with significant portions of DMPO-OH resulting from both OH and singlet oxygen. In fact, the DMPO-OH resulting from OH should be carefully calculated by correcting for the amount of DMPO-OH due to singlet oxygen. This study reports, for the first time, that the goethite suspensions may also act as a natural sensitizer, such as fulvic acids, to form singlet oxygen. 相似文献
507.
Seong-Wan Kang Jong-In Dong Jong-Min Kim Woo-Chan Lee Won-Gu Hwang 《Journal of Material Cycles and Waste Management》2011,13(3):180-185
Various research has attempted to determine the proper treatment of sewage sludge, including thermal technologies. Efficient
thermal technologies have been focused on because of their energy saving/energy recovery. Gasification technology can be considered
one of these approaches. In this study, the characteristics of gasification reactions were investigated with the aim of finding
fundamental data for utilizing sewage sludge as an energy source. For the experiments on sewage sludge gasification reaction
characteristics, a laboratory-scale experimental apparatus was set up with a fluidizing bed reactor of 70-mm inner diameter
and 600-mm total height using an electric muffle furnace. The experimental materials were prepared from a sewage treatment
plant located in Seoul. The reaction temperature was varied from 630 to 860°C, and the equivalence ratio from 0.1 to 0.3.
The gas yields, compositions of product gas, and cold gas efficiencies of product gas were analyzed by GC/TCD and GC/FID installed
with a carboxen-1000 column. The experimental results indicated that 800°C, ER 0.2 was an optimum condition for sewage sludge
gasification. The maximum yield of product gas was about 44%. Producer gas from experiments was mainly composed of hydrogen,
carbon monoxide, carbon dioxide, and methane. The cold gas efficiency of sewage sludge gasification was about 68%. The H2/CO ratio and CO/CO2 ratio were about 1.1 and 1.4, respectively, in optimum reaction conditions. Gaseous pollutants such as SO2, HCl, NH3, H2S, and NO2 were also analyzed at various gasification/combustion conditions, and their gaseous products were compared, showing significantly
different oxidized product distributions. 相似文献
508.
The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels 总被引:4,自引:0,他引:4
Ryu J Khim JS Kang SG Kang D Lee CH Koh CH 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2622-2629
The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species. 相似文献
509.
为了研究生物膜水解-好氧循环系统处理蒽醌类染料活性艳蓝RB-19效果及其中微生物群落动态变化,利用基于16S rDNA的PCR-DGGE技术获得了微生物群落的DNA特征指纹图谱。结果表明,该系统能有效地降解活性艳蓝RB-19模拟废水,在RB-19浓度≤400 mg/L时,RB-19去除率维持在82%~96%之间,COD去除率维持在95%左右,但当RB-19浓度提高到500 mg/L时,RB-19去除率降低到58%,COD去除率降低到85%。DGGE分析表明,生物膜上的微生物群落结构随着RB-19浓度递增有显著变化,好氧、水解反应器内的细菌Shannon指数分别从1.32和1.20降低到1.11和1.19。UPGMA聚类分析和NMDS散点分析表明,水解、好氧反应器内的微生物并没有因为同处一个系统内而使得其菌群落结构产生明显的趋同倾向。系统内的多种优势菌群为兼性细菌,克隆测序的结果发现,在水解反应器存在一类具有很强还原能力的古细菌——Methanobacterium sp.MB4。 相似文献
510.
典型高混接率分流制排水泵站雨天放江污染特征研究 总被引:1,自引:0,他引:1
通过对上海市中心城区典型分流制系统z泵站汛期降雨放江水质水量分析,在调查系统服务区特点、泵站运行和开展现场实测的基础上,得出如下结论:(1)由于管网系统混接情况严重,加上高水位运行、雨前预抽空等原因,Z泵站汛期放江频率高,污染严重;(2)放江污染物的EMC在不同雨型情况下表现不同,溶解性污染物随降雨量的增大而降低,而包含悬浮物的污染指标呈先升后降的变化趋势,这主要与管道沉积物特征有关;(3)随着降雨量的增大,泵站的放江负荷量显著增加。在同等降雨条件下,前峰雨使得泵站放江污染负荷远大于后峰雨;(4)受雨型与预抽空的影响,不论小雨、中雨、大雨,SS初期效应均不显著;COD与TP主要来源于管道沉积污染物,初期效应显著;溶解态污染物初期效应显著,不受降雨雨量与雨型的影响;(5)为有效降低Z泵站降雨放江污染负荷,提出包括雨污混接改造、优化泵站运行、提高截流能力、疏通管道等措施在内的污染控制策略。 相似文献