Influence of the DMPP (3,4-dimethyl pyrazole phosphate) on nitrogen transformation and leaching in multi-layer soil columns

The application of nitrogen fertilizers leads to various ecological problems such as nitrate leaching. The use of nitrification inhibitors as nitrate leaching retardants is a proposal that has been suggested for inclusion in regulations in many countries. In this study, using a multi-layer soil column device, the influence of new nitrification inhibitor DMPP (3,4-dimethyl pyrazole phosphate) was studied for understanding the nitrogen vertical transformation and lowering the nitrate leaching at different soil profile depths. The results indicated that, within 60 d of experiment, the regular urea added 1.0% DMPP can effectively inhibit the ammonium oxidation in the soil, and improve the ammonium concentration in soil solution over the 20cm depths of soil profile, while decline the concentrations of nitrate and nitrite. No obvious difference was found on ammonium concentrations in soil solution collected from deep profile under 20cm depths between regular urea and the urea added 1.0% DMPP. There was also no significant difference for the nitrate, ammonium and nitrite concentrations in the soil solution under 40cm depths of soil profile with the increasing nitrogen application level, among the treatments of urea added 1.0% DMPP within 60 d. It is proposed that DMPP could be used as an effective nitrification inhibitor in some region to control ammonium oxidation and decline the ion-nitrogen leaching, minimizing the shallow groundwater pollution risk and being beneficial for the ecological environment.     

Bioavailability to grains of rice of aged and fresh DDD and DDE in soils

DDT had been widely used around the world before 1980s and is still under production and use for non-agricultural purposes in China. Because of their special physicochemical properties, p,p'-DDT and its main metabolites, p,p'-DDD and p,p'-DDE, accumulated and persisted in the environment, presenting potential menace on biota. A green-house study was conducted to determine the bioavailability of p,p'-DDD and p,p'-DDE to grains of rice and the influences of traditional Chinese farming practices on their bioaccumulation. Paddy rice and dry rice were grown in submerged paddy soils and non-submerged upland soils, respectively. Two types of soil, Hydragric Anthrosols (An) and Hydragric Acrisols (Ac), were employed. Bioaccumulation factors (BAFs) of DDE ranged from 0.67 for rice grown in non-submerged An to 0.84 in submerged An in the control group, whilst BAFs were all below 0.04 in experimental groups. BAFs of DDD varied from 1.39 for submerged An to 2.26 for submerged Ac in original soils. In contrast, BAFs were between 0.05 for non-submerged Ac and 0.08 for submerged An in DDD-contaminated soils. Flooding seemed to have two contradictory effects on the DDE/DDD accumulation by rice: on one hand, it made the pollutants more mobile and bioavailable; while on the other hand, it enhanced the degradation and binding of POPs. Adding rice straw to the soils protected DDE from being taken up yet promoted DDD accumulation by rice. Furthermore, the distinct inorganic component of the soils might also play an important role in the environmental activities of POPs.     

Biohydrogen production through fermentation using liquid swine manure as substrate

In this paper, continuous production of hydrogen through fermentation with liquid swine manure as substrate was researched using a semi-continuously fed fermenter (8 L in total volume and 4 L in working volume). The pH and temperature for the fermenter were controlled at 5.3 +/- 0.1 and 35 +/- 1 degrees C, respectively, throughout the experiment. Three hydraulic retention times (16, 20, and 24 h) were investigated for their impact on the efficiency and performance of the fermenter in terms of hydrogen yields. The results indicate that hydraulic retention time (HRT) has a strong influence on the fermenter performance. An increasing HRT would increase the variation in hydrogen concentration in the offgas. To produce hydrogen with a fairly consistent concentration, the HRT of the fermenter should not exceed 16 h, which, however, did not appear to be short enough to control methanogenesis because the offgas still contained about 5% methane. When methane content in the offgas exceeded 2%, an inverse linear relationship between hydrogen and methane was observed with a correlation coefficient of 0.9699. To increase hydrogen content in the offgas, methane production has to be limited to below 2%. Also, keeping oxygen content in the fermenter below 1.5% would increase the hydrogen concentration to over 15%. The product to substrate ratio was found to be around 50% for the fermenter system studied, evidenced by the observation that for every 6 liters of manure fermented, 3 liters of pure hydrogen were produced, which was significant and encouraging.     

昆明市城中村火灾事故统计分析

城中村是中国快速城市化进程中的一个普遍现象,由于缺乏统一规划和专门管理,城中村的高火灾风险成为当前面临的重要问题并得到社会各界关注.为获得昆明市城中村火灾的特点和规律,从2004-2006年昆明市火灾统计记录中区分出城中村和非城中村火灾数据,在此基础上采用Bayes统计分析城中村不同用途建筑物的火灾发生概率及概率比例.结果表明,相比城中村其他用途的建筑,居住用房火灾概率较低,而具有生产和加工性质的行业作坊、易燃易爆场所和娱乐场所的火灾概率较高,分别是居住用房的48倍、26倍和18倍.进一步采用火灾原因-场所关联对比分析了城中村和非城中村火灾的特点.从火灾发生场所看,与非城中村相比,城中村居住场所火灾发生比例高7.2%,路边可燃物高88.8%,木材、家具加工厂高184.8%,易燃易爆场所高521.4%; 从火灾原因看,城中村电气、电线短路致灾比例高1 2%,限制行为能力人(小孩和精神病人)致灾比例高65 1%,燃放烟花爆竹致灾比例高3.5%,吸烟致灾比例高50.9%,违章操作致灾比例高59.0%.这些差异基本上反映了城中村的主要外在特征,这些外在特征经城中村实地调研得到证实.     

TiO2-xNx光催化氧化苯甲酸的研究

采用悬浮态光催化反应体系,以氙灯为光源,自制纳米TiO2-xNx为催化剂,考察了苯甲酸光催化氧化过程中TiO2-xNx质量浓度、反应体系初始pH和苯甲酸初始质量浓度对苯甲酸溶液中TOC去除率的影响。实验结果表明：最佳催化剂质量浓度为0．30g／L;TiO2-xNx的等电点为pH=5．3,在酸性条件下（pH=2．0）更有利于苯甲酸在催化剂表面的吸附,以及光生电子与O2反应生成·OH的进行;随苯甲酸初始质量浓度增加,TOC去除率降低,反应速率也相应地降低。TiO2-xNx比P25型TiO2表现出更强的浓度适应能力。     

电源变压器温升试验中（绕组法）的影响因素及不确定度的评估

本文中探讨的是根据绕组法计算电源变压器绕组温升的试验方法,以及对整个试验过程中环境、仪器设备、仪表、人为因素所引起的误差等对最终试验结果的影响,并对其测量不确定度进行评估。     

家居室内设计及新进展的思考

在对传统室内设计基本观点阐述与理解的基础上分析其整体性、可持续发展,并着重探讨在物质文明和精神文明高度发展的今天,现代室内设计在个性化、自然性、现代性、艺术性等方面发展的新趋势.通过对现代室内设计特点和发展趋势的分析,创造出一个适合人们现代生活的理想空间.     

Radiation-induced degradation of methyl orange in aqueous solutions

Degradation of methyl orange under gamma-irradiation was investigated. The reactions followed pseudo first-order kinetics. Apparent degradation rate constant, estimated through linear regression analysis, increased with an increase of dose rate and a decrease of initial methyl orange concentration. Degradation of methyl orange was significantly accelerated under oxidative condition, but was slightly enhanced under reductive condition. However, the result of decoloration was better under reductive condition than oxidative one. An analysis on the intermediates using Fourier transform infrared and gas chromatography/mass spectrometry demonstrates that the radiolytic degradation of methyl orange was processed with different C-N cleavages under oxidative and reductive conditions.     

Sorption of pentachlorophenol on surficial sediments: the roles of metal oxides and organic materials with co-existed copper present

The sorption characteristics of pentachlorophenol (PCP) in the surficial sediments were investigated using a selective extraction procedure. The results show that the Gamma(max) of PCP sorption decreased from 1.60mumolg(-1) to 0.69mumolg(-1) by approximately 60% after selective removal of organic materials from the sediments. The sorption of PCP in the sediments after selective removal of Mn oxides increased nearly up to 600% (from 1.60mumolg(-1) to 11.11mumolg(-1)) and, to a less degree, the PCP sorption in the sediments after simultaneous removal of Fe/Mn oxides (Gamma(max)=3.53mumolg(-1)). The analysis of the data using an additional model indicates that the contribution of Mn oxides to PCP sorption was negative, and Fe oxides and organic materials both have greater potential for sorption of PCP with less contribution from residues including Mn and Fe oxides in the residual fractions determined by a sequential extraction procedure and clay and silicate minerals. The differences in the decreased degrees of PCP sorption with increasing of Cu suggest that competition between Cu and PCP for sorption sites mainly takes place on Fe oxides.