巢湖低温高效聚磷菌的筛选及其特性

采用低温富集培养及混合平板分离技术,从巢湖底泥中分离筛选得到2株在低温下仍具有较高效能的菌株D3、D6,经过厌氧/好氧交替培养,2种菌株在低温下(8℃)的除磷率均达到80%以上。在低温下,研究了p H、微量元素对2株菌株生长及除磷率的影响,实验结果表明,2株菌都具有广泛的温度适应性,适宜其生长和除磷的p H为中性偏碱,微量元素的缺乏对2株菌株的生长和除磷效果有不同程度的不良影响。染色观察显示,厌氧培养时菌体内聚羟基丁酸(PHB)颗粒明显增多,转为好氧培养后异染颗粒增多,为典型的聚磷菌特征。经鉴定,2株菌均属假单胞菌属。     

活性炭涂层电极电容去离子的性能

采用活性炭涂层电极构建电容去离子吸附装置,以氯化钠模拟含盐原水,研究电压、流量、进水浓度等操作参数对活性炭涂层电极脱盐效率和能耗的影响。实验结果表明,去除率和比吸附量随着电压的增大而增加,且比能耗随之增大。流速越小,出水的浓度越低,当对出水的浓度要求较高时,宜采用小流速。当进水浓度低于活性炭涂层电极的饱和吸附量时,比吸附量随着进水浓度呈线性增加;当达到饱和吸附量时,比吸附量不会随进水浓度的增大而发生改变;比能耗随着进水浓度的增加而降低。     

固定化斜生栅藻净化畜禽废水中氨氮和磷的影响因素

为探讨Cu2+、p H和流速对固定化斜生栅藻去除畜禽废水中NH+4-N、TP效果的影响,在实验室条件下模拟实际污水处理过程,并采用正交实验方案对结果进行分析。结果表明低质量浓度Cu2+(0~0.05 mg/L)改善藻的净化效果,高质量浓度Cu2+(0.50~5.00 mg/L)抑制藻的净化效果;在p H较高的条件下(p H=9),固定化斜生栅藻的净化效果明显提高;流速对结果没有明显影响。通过正交实验,得出固定化斜生栅藻去除畜禽废水中NH+4-N、TP的优化条件如下:Cu2+质量浓度为0.05 mg/L,p H为9,流速为0.3 m/s。此时NH+4-N去除率为96.11%,TP去除率为97.53%。     

大空间单跨门式刚架结构抗火性能影响因素的客观权重研究

火灾时的大空间单跨门式刚架结构抗火性能,受钢构件温升和结构整体抗火临界温度的影响.本文通过对无保护大空间建筑钢构件温升数据的统计分析,获得包含火源功率、建筑体积、钢构件截面形状系数的钢构件温升拟合公式;结合单跨门式刚架结构整体抗火临界温度数据的统计分析,获得包含荷载比、柱高和系数K的结构整体抗火临界温度拟合公式;通过分...     

抗生素废水的铁屑微电解预处理研究

研究了采用铁屑微电解法预处理抗生素废水.在进水COD质量浓度为6.2 g/L时,试验结果表明,经微电解处理后的废水,COD和色度的去除率分别达到68.3%和79.3%,BOD5/COD从0.306提高到0.56,废水的可生化性得到显著提高.通过正交试验考察pH、反应时间及铁屑用量对处理效果的影响,并对各因素作了单因素影响试验,确定了最佳工艺条件.     

基于FA-BAS-ELM的海洋油气管道外腐蚀速率预测

为提高海洋油气管道外腐蚀速率预测的精度和效率,建立基于因子分析(FA)和天牛须搜索算法(BAS)的极限学习机(ELM)腐蚀速率预测模型。利用FA对影响因素数据集进行降维处理,确定预测模型的输入变量;建立ELM预测模型,并采用BAS对ELM模型的参数进行优化,避免参数取值随机性对模型预测性能的影响;以实海挂片试验为例,通过建模仿真评价模型的预测性能,并与其他模型进行对比分析。结果表明：FA-BAS-ELM预测模型的平均绝对误差(MAPE)仅为1.92%,决定系数R²高达0.994 9,相比于其他模型,该模型具有更优的预测性能。     

Earthworm cast production as a new behavioural biomarker for toxicity testing

There is currently a lack of ecotoxicity tests adapted to earthworm species of higher ecological relevance and whose endpoints could be directly related to their ecological role in the soil. We propose a new and relatively simple ecotoxicity test based on the estimation of cast production (CP) by Lumbricus terrestris under laboratory conditions. CP was found to be linearly correlated to earthworm biomass and to be greatly influenced by soil water content. Azinphos-methyl had no effect on CP at all the concentrations tested. Significant decreases were observed at the normal application rate for other pesticides with (imidacloprid, carbaryl, methomyl) or without (ethyl-parathion and chlorpyrifos-ethyl) a clear concentration-effect response. For the highest concentration tested, reduction in CP varied between 35 and 67%. CP is straightforward and rapidly measured and ecologically meaningful. We thus believe it to be of great use as an endpoint in ecotoxicity testing.     

Defining Historical Baselines for Conservation: Ecological Changes Since European Settlement on Vancouver Island,Canada

Abstract: Conservation and restoration goals are often defined by historical baseline conditions that occurred prior to a particular period of human disturbance, such as European settlement in North America. Nevertheless, if ecosystems were heavily influenced by native peoples prior to European settlement, conservation efforts may require active management rather than simple removal of or reductions in recent forms of disturbance. We used pre‐European settlement land survey records (1859–1874) and contemporary vegetation surveys to assess changes over the past 150 years in tree species and habitat composition, forest density, and tree size structure on southern Vancouver Island and Saltspring Island, British Columbia, Canada. Several lines of evidence support the hypothesis that frequent historical burning by native peoples, and subsequent fire suppression, have played dominant roles in shaping this landscape. First, the relative frequency of fire‐sensitive species (e.g., cedar [Thuja plicata]) has increased, whereas fire‐tolerant species (e.g., Douglas‐fir [Pseudotsuga menziesii]) have decreased. Tree density has increased 2‐fold, and the proportion of the landscape in forest has greatly increased at the expense of open habitats (plains, savannas), which today contain most of the region's threatened species. Finally, the frequency distribution of tree size has shifted from unimodal to monotonically decreasing, which suggests removal of an important barrier to tree recruitment. In addition, although most of the open habitats are associated with Garry oak (Quercus garryana) at present, most of the open habitats prior to European settlement were associated with Douglas‐fir, which suggests that the current focus on Garry oak as a flagship for the many rare species in savannas may be misguided. Overall, our results indicate that the maintenance and restoration of open habitats will require active management and that historical records can provide critical guidance to such efforts.     

Diffusion mechanism of lindane into wood charcoal

Abstract

The wood charcoal treated by 1N HNO₃ (WCT) was used to remove toxic chlorinated pesticide lindane (y‐HCH) residue from water by the sorption process. Using a simple first order reversible kinetics constants and half time equations, the film and pore diffusion coefficients were determined. Film diffusion was found to be rate limiting step in sorbing lindane by WCT. This was further authenticated by kinetics studies at different initial sorbate concentrations, different sorbent sizes, and different agitation speeds besides interruption test. A pore diffusion model was used to fit the data of kinetics in continuously mixed batch reactors (CMBR), and the tortuosity, external resistance, and surface diffusion effects on lindane sorption by WCT were noticed. The tortuosity values of 15 to 28 were obtained for WCT‐lindane system.     

Photodegradation of sulfonamide antibiotics in simulated and natural sunlight: Implications for their environmental fate

The photochemical fate of seven sulfonamides was investigated in matrices representative of natural water bodies under various light sources. Fundamental photolysis parameters such as molar absorption coefficient, quantum yield (QY) and first-order rate constants were determined. The photolysis decay rate was dependent on the protonation state of the molecule, pH of the water sample and dissolved organic matter. Natural organic matter was the most significant factor in the indirect photolysis of sulfonamides. Half-lives were in the range of minutes at 254 nm to days under natural sunlight. Under natural sunlight, all sulfonamides showed higher removal rates in natural waters implying that indirect photolysis is the predominant mechanism.