Assessment of sociocultural acceptability of biogas from faecal waste as an alternative energy source in selected areas of Benin City,Edo State,Nigeria

Environment, Development and Sustainability - The use of wastes for biogas production has been restricted to few feedstock like cattle manure and food waste. Increasing the feedstock base for...     

硝基苯、苯酚衍生物对发光菌毒性定量构效关系研究

采用发光细菌法测定14种硝基苯、苯酚衍生物对发光菌的毒性,得到各化合物的半数有效浓度（15minEC50值）。选用辛醇/水分配系数（logP）、分子最低空轨道能（ELUMO）和平均超离域性（S^N_av）作为参数,与logl/EC₅₀值进行定量构效关系（QSAR）研究。结果表明,硝基苯衍生物对发光菌的毒性与分子的电性参数（ELUMO或S^{N_av）相关;而苯酚衍生物的毒性可分别由疏水性参数（logP）和电性参数（ELUMO或SN_av）来描述。采用以Snav为参数的QSAR模式预测了14种试验化合物对发光菌的毒性}     

Historical pollution of seldom monitored trace elements in Sweden--Part B: sediment analysis of silver, antimony, thallium and indium

Sediment cores from four boreal and remote lakes in a south to north transect in central Sweden were analysed for acid leachable silver, antimony, thallium and indium in the solid sediment phase and the corresponding porewater. Dating of the cores was made by their content of acid leachable lead and the (206)Pb/(207)Pb ratio, in one lake also by (210)Pb. The impact of diagenesis on element redistribution in the sediments was included and found to be minor except for thallium. The results show lowered concentrations towards the north and most intense accumulation after the Second World War, which is taken as evidence for atmospheric deposition being the primary source. Indium has declining concentrations in recent strata while silver and antimony increase. Thallium has lowered acid-leachable concentrations in recent strata. For all metals the impact of domestic industrialisation as well as the early industrialisation of central Europe is discernible. Only thallium appears to reach a geological background at depths that correspond to the late 18th century. For the other metals elevated levels are concluded.     

乌江干流中上游水电梯级开发水温累积效应

以乌江流域洪家渡库尾至乌江渡坝下的水电工程干扰典型段为研究区域,利用建坝前后的水温实测资料,采用建坝前天然水温和建坝后下泄水温比较法,对乌江干流梯级水库水温时空分布特征进行分析。研究结果表明：对天然水温改变最大的电站为洪家渡和乌江渡,前者是受水库水温结构自身影响,后者是梯级联合运行的结果;梯级联合运行使库区水温分层有所减弱,随着时间的推移或上游梯级电站的建成,电站下泄水温年变化过程趋于均化,与天然水温的延迟也越加明显;不同的水库水温结构对水温累积效应的影响也各不相同,稳定分层型水库对水温累积具有正效应,混合型水库具有负效应,过渡型水库处于两者之间,体现了梯级电站的水温累积影响,为研究减缓下泄低温水的对策措施提供依据和参考。     

Fractionation of Cd,Cr, Pb and Ni in roadside soils of Uyo,Niger Delta Region: Nigeria using the optimized BCR sequential extraction technique

The optimized BCR sequential extraction procedure was applied to nine roadside soil samples for the determination of Cd, Cr, Pb and Ni. The extractable metals were isolated into three operationally defined fractions viz: acid extractable, reducible and oxidizable. The residue was treated with aqua regia solution. Metal analysis was done using flame atomic absorption spectrophotometry with air–acetylene flame. Results obtained showed the concentrations of the metals as relative abundance in the mobile phases of the samples (based on the sum of the first three fractions) are in the following order: Cd(91.9) > Pb(82.8) > Ni(49.5) > Cr(39.0). The most non-mobilizable metals were Cr and Ni which are generally lithogenic, associated with the silicate matrix, and the order is as follows: Cr(61.0) > Ni(50.5) > Pb(17.2) > Cd(8.1). The recovery of all the metals expressed as the ratio of total metal concentration to fractional sum of the optimized BCR sequential extraction procedure was of the order: Cr(95.6) > Pb(95.0) > Ni(94.8) > Cd(92.4).     

On the importance of the meteorological coupling interval in dispersion modeling during ETEX-1

Traditionally, transport and dispersion models are offline coupled to meteorological drivers, receiving pre-processed output at regular coupling intervals. However, today meteorological models have reached urban and cloud resolving scales and online models integrating meteorological and dispersion models have been developed. In this study the online coupled model, Enviro-HIRLAM, which can also run in offline mode, was used to compare online and offline representations of meso-scale disturbances. The online model was evaluated using data from the first European Tracer Experiment (ETEX-1) and produced satisfactory results. Meso-scale influences during the simulation pertube the plume during long-range transport, leading to a double peak structure at a specific measurement station. The meso-scale influence was investigated by varying the offline coupling interval which was shown to be important in constraining the influence of meso-scale disturbances on plume structure in coarse resolution.     

Comparison of models used for national agricultural ammonia emission inventories in Europe: Litter-based manure systems

Six N-flow models, used to calculate national ammonia (NH₃) emissions from agriculture in different European countries, were compared using standard data sets. Scenarios for litter-based systems were run separately for beef cattle and for broilers, with three different levels of model standardisation: (a) standardized inputs to all models (FF scenario); (b) standard N excretion, but national values for emission factors (EFs) (FN scenario); (c) national values for N excretion and EFs (NN scenario). Results of the FF scenario for beef cattle produced very similar estimates of total losses of total ammoniacal-N (TAN) (±6% of the mean total), but large differences in NH₃ emissions (±24% of the mean). These differences arose from the different approaches to TAN immobilization in litter, other N losses and mineralization in the models. As a result of those differences estimates of TAN available at spreading differed by a factor of almost 3. Results of the FF scenario for broilers produced a range of estimates of total changes in TAN (±9% of the mean total), and larger differences in the estimate of NH₃ emissions (±17% of the mean). The different approaches among the models to TAN immobilization, other N losses and mineralization, produced estimates of TAN available at spreading which differed by a factor of almost 1.7. The differences in estimates of NH₃ emissions decreased as estimates of immobilization and other N losses increased. Since immobilization and denitrification depend also on the C:N ratio in manure, there would be advantages to include C flows in mass-flow models. This would also provide an integrated model for the estimation of emissions of methane, non-methane VOCs and carbon dioxide. Estimation of these would also enable an estimate of mass loss, calculation of the N and TAN concentrations in litter-based manures and further validation of model outputs.     

Spermatophore characteristics in bushcrickets vary with parasitism and remating interval

Male bushcrickets provide females with a nuptial gift, a spermatophore, which is transferred to females at mating. The spermatophore consists of a gelatinous mass, the spermatophylax, and the sperm-containing ampulla. Male spermatophore size is positively correlated with insemination rate and female refractory period and therefore with male reproductive success. In this study, we examined spermatophylax weight, ampulla weight and sperm number in males of Poecilimon mariannae parasitized by the acoustically orienting fly Therobia leonidei. We show that in parasitized males, spermatophylax weight decreases with the level of parasitism. In line with the hypothesis that parasitism is a cost to reproduction, we found that spermatophylax weight was reduced at remating. In contrast, the replenishment of the spermatophylax in unparasitized males was complete after 2 days and was increased no further after 3 days. Both sperm number and ampulla weight showed an increase over time since last mating and sperm production was estimated at a constant rate of 500,000 per day in all individuals, regardless of parasitism. The allocation of investment in components of the spermatophore varies greatly with parasitism and remating. Both factors had rather independent effects on spermatophore constitution, revealing functional constraints acting on spermatophore characteristics in bushcrickets, which are important for understanding the selection pressures working on its components. Received: 13 September 1999 / Received in revised form: 4 February 2000 / Accepted: 13 March 2000     

Ecological risk analysis of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Laizhou Bay

The current research aims at developing predictive models for trihalomethane (THM) formation in Lebanon based on field-scale investigations as well as laboratory controlled experimentations. Statistical analysis on field data revealed significant correlations for TTHM with chlorine dose, Specific UV-A, and UV(254) absorbing organics. Simulated distribution system-THM tests showed significant correlations with applied chlorine dose, total organic carbon, bromides, contact time, and temperature. Predictive models, formulated using multiple regression approaches, exhibiting the highest coefficients of determination were quadratic for the directly after chlorination (DAC; r(2) = 0.39, p < 0.036) and network (r(2) = 0.33, p < 0.064) THM databases, and logarithmic for the laboratory simulated THM database (r(2) = 0.70, p < 0.001). Computed r(2) values implied low correlations for the DAC and network THM database, and high correlation for the laboratory simulated THM database. Significance of the models were at the 0.05 level for DAC database, 0.10 level for the network database, and very high (<0.01 level) for the laboratory simulated THM database. It is noteworthy to mention that no previous attempts to assess, monitor, and predict THM concentrations in public drinking water have been reported for the country although a large fraction of the population consumes chlorinated public drinking water.     

现代企业安全管理信息系统的构建

论述现代企业安全管理信息系统的功能需求、基本框架、核心功能和系统特点。该系统把信息技术、网络技术及GIS应用到企业安全管理中,并融入安全学习志的管理理念,同时对基于联动机制的企业安全应急决策系统综合理论及其应用进行了研究。通过该系统的建立,使安全管理工作逐步走向科学化、系统化和规范化,对提高目前安全管理水平具有实际意义。