TiO2/SiO2/γ-Fe2O3的表征及其光催化降解染料废水

以γ-Fe2O3为磁性核心,通过溶胶-凝胶法制备出三层结构的复合光催化剂TiO2/SiO2/γ-Fe2O3.通过X射线衍射、扫描电镜、透射电镜、振动样品磁强计和紫外-可见分光光谱分析进行表征.SiO2包覆膜可以减弱内层γ-Fe2O3对光催化效果的不利影响,有效地阻隔高温时γ-Fe2O3磁核与TiO2之间的熔结.以亚甲基...     

洋河水库水华优势种演替的原因分析

针对鱼腥藻和微囊藻这2种洋河水库水华暴发常见优势藻,研究了其在不同温度及硝态氮浓度下的生长情况。结果表明,在温度15～25℃,硝态氮浓度0.05～10 mg/L的范围内,温度的升高、硝态氮浓度的增加,对鱼腥藻的生长影响不明显,却能够明显地促进微囊藻的增长。15℃或0.05 mg/L硝氮条件下,鱼腥藻的比增长速率高于微囊藻,而25℃或10 mg/L硝氮时,微囊藻的比增长速率分别达到了0.425 d-1和0.466 d-1,明显超过鱼腥藻。洋河水库逐年升高的硝态氮浓度以及夏秋季节比较适宜的温度促进了微囊藻的增长,可能是洋河水库水华优势种由螺旋鱼腥藻向微囊藻转变的重要因素。     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于污染权角度的流域生态补偿模型及应用

生态补偿标准的测算一直是理论界的研究重点,本文对相关文献进行综述,将现有的研究方法划分为费用分析法、机会成本法、支付意愿法和水资源价值法等,分别评述了各种方法的特点、优劣以及在我国流域生态补偿研究应用中的主要结论,在此基础上,基于污染权角度,采用机会成本法和水资源价值法,构建了一个基于计量经济学的流域生态补偿标准测算模型,其核心在于强调了流域上下游居民均有适当的"污染权",即便在上游地区达标排放的前提下,由于下游地区对水质的较高要求,借助行政手段对上游地区采取了较强的环境管制,在缺乏足够生态补偿的情况下,上游地区由于环境管制而放弃了部分"污染权",也即是其为了更高的环境标准而放弃的机会成本,这部分机会成本可以视作下游需要向上游支付的生态补偿金额.以浙江飞云江流域为例,利用该模型测算出下游温州市每年应向上游文成县提供3.24亿元的生态补偿,用于购买文成县为保护温州市"大水缸"所放弃的污染权.     

盐沼枯落物碳氮和有色溶解有机物淋溶过程研究

盐沼枯落物的短期淋溶过程对东滩沿岸的水质有重要影响.采用东滩3种典型盐沼植物的茎和叶的枯落物为材料进行为期48h的室内浸泡模拟实验.利用有机碳探测分析仪测定不同时间的可溶性有机碳(DOC)和总可溶性氮(TDN)浓度然后转换为累积释放量,通过紫外可见光光谱参数表征有色溶解有机物(CDOM)浓度,结合三维荧光光谱(EEMs)和平行因子(PARAFAC)分析推断CDOM的荧光组分的变化特征.结果 表明在淋溶释放的最初48 h,DOC、TDN、CDOM、两个类腐殖质荧光组分和两个类蛋白荧光组分的释放过程呈对数曲线状,最初8h增长迅速,8～48 h则增幅减缓或出现小幅下降趋势.不同种类的植物以及同种植物的不同部位的初始基质对枯落物的DOC和TDN释放量有显著影响.TDN最大累积释放量与初始基质有机碳和氮含量呈显著的正相关.枯物体中的氮比有机碳更容易淋失.各个荧光组分的贡献率变化不大,但不同植物种类之间存在显著差异,由此可以推断枯落物的初期淋溶以物理性过程为主.我们的研究结果表明,盐沼枯落物的淋溶对潮滩水水质有着显著的影响.     

Application of plant carbon source for denitrification by constructed wetland and bioreactor: review of recent development

Water quality standard for nitrate becomes more and more strict, and the plant carbon source is widely used for denitrification by constructed wetland (CW) and bioreactor. However, the nitrate removal efficiency by different types of plant carbon source are not evaluated comprehensively. Denitrification performance of different plant carbon sources, and the influence of dosing method and pretreatment are thoroughly reviewed in this paper, which aims to investigate the accurate utilization of plant carbon source for nitrogen (as nitrate) removal. It is concluded that plant carbon source addition for all types of CWs and bioreactors can improve the nitrate removal efficiency to some extent, and the dosing method of plant carbon source for denitrification should be further studied and optimized in the future. The popular carbon sources for CW and bioreactor denitrification enhancement are woodchip, chopped macrophytes, crop plants, macrophytes litters, etc. The recommended optimum C:N ratios for CW and bioreactor are 4.0:5.0 and 1.8:3.0, respectively. The physical and biological pretreatments are selected to supply organic carbon for long-term denitrification.     

Effect of alkali catalyst on biodiesel production in South Korea from mixtures of fresh soybean oil and waste cooking oil

Biodiesel from waste cooking oil (WCO) and soybean oil (SO) mixture was produced by changing the alkali catalyst (NaOH) content and the WCO to SO ratio in the feedstock. All the prepared biodiesel samples satisfied the standard requirement in terms of free glycerol, density, and acid value. The minimum catalyst content and the highest WCO composition to get biodiesel from the WCO/SO mixture feedstock without ruining the biodiesel properties were 1.0 and 60 wt %, respectively. This conclusion implies that the waste cooking oil mixture, which contains 40 wt % fresh soybean oil, could be treated like the fresh soybean oil to produce biodiesel, and that this behavior would be helpful to reduce the biodiesel production cost when waste cooking oil used as feedstock. The unsaturated methyl esters such as linoleic, and oleic acid were dominant (almost 80 % w/w) in the fresh soybean oil. However the saturated methyl ester was increased due to the double bond breaking during the frying process. These results may deteriorate the biodiesel quality by changing the methyl ester composition.     

Microbially mediated aerobic and anaerobic degradation of acrylamide in a western United States irrigation canal

Acrylamide (AMD), a neurotoxin and suspected carcinogen, is present at concentrations of up to 0.05% in linear anionic polyacrylamide, which is under evaluation as a temporary sealant in unlined irrigation canal systems across the United States. We examined the microbially mediated degradation of AMD and diversity of AMD-degrading microbial physiotypes in the Rocky Ford Highline Canal, Colorado to better constrain the potential fate ofAMD in a canal environment. Microorganisms able to use AMD (500 mg L(-1)) as a sole nitrogen source were relatively abundant (2.3 x 10(3) to 9.4 x 10(3) cells mL(-1) in water and 4.2 x 10(3) to 2.3 x 10(5) cells g(-1) in sediment). Only sediment samples contained microorganisms able to use AMD as a sole carbon source. Acrylamide (up to 100 mg L(-1)) was efficiently removed from amended canal water and sediment slurries under aerobic conditions, but no AMD degradation was observed in abiotic controls. Anaerobic degradation of AMD by nitrate-, sulfate-, and iron-reducing microorganisms was also tested, with nitrate reducers affecting the highest amounts of AMD removal (70.3-85%) after 60 d. All representatives (n=15) from a collection of 256 AMD-degrading microbial isolates from Rocky Ford Highline Canal were closely related to well characterized environmental bacteria capable of facultative nitrate respiration. Our results demonstrate that natural microbial populations within this canal are capable of AMD degradation under aerobic and anaerobic conditions and that this degradation is performed by naturally abundant bacteria likely to be present in other freshwater irrigation canals or similar lotic habitats.     

Spatial Organization Mechanism of Aircraft Manufacturing

Unquestionably, aircraft industry plays an important part in both economy and security of a nation. However, few of articles have dealt with the spatial development of this industry sector. The purpose of this article is to analyze the dynamics of agglomeration and diffusion of aircraft industry.In a historical view, with some spatial analysis methods, this research discusses the characteristics and patterns of aircraft industry's spatial organization and evolution, globally, nationally and regionally respectively. We find out there is a 'Matthew effect' in aircraft industry of the world, and the spatial evolution of the industry is consistent with the nation's industrialization process. Then, it concludes that the main agglomeration forces consist of capital, talents, technology and cluster's advantages, and the main diffusion forces include comparative advantages, cost and risk sharing, emerging markets, development policy for backward regions and military requirements. All the factors can be divided into market forces making the spatial development of aircraft industry normal and non-market forces making that irregular. In particular, lessons from the USA and France are expected to be conducive to the rise of China's aircraft industry in the future.     

冬季减排对广东省空气污染的影响分析

使用WRF-SMOKE-CAMx模型模拟了2017年1月广东省各市的主要大气污染物,模型对SO 2,O 3,PM 10和PM 2.5的模拟效果较好,但对NO 2存在低估,目前的排放源清单可能普遍低估了NO x的排放量。与基准年2015年相比,预测2020年广东省人为源的SO 2,NO 2,CO,PM 10,PM 2.5,VOCs,NH 3排放分别下降40%,32%,37%,23%,25%,31%,18%。在气象场与2017年1月一致的假设下,2020年同期广东省各市平均NO,NO 2,SO 2,PM 10,PM 2.5月均值下降率分别为31%,19%,17%,14%,14%。O 3平均浓度出现反弹,涨幅均值为11%,主要是由NO滴定效应减弱导致,显示了广东省臭氧污染防治的难度。不同地区气态污染物浓度变化率存在较大差异,2020年冬季珠三角地区的臭氧浓度上升显著,粤东与粤北的上升幅度相对较低;各市气溶胶的变化率相对较接近。