生物扰动作用对河口沉积物中荧蒽去除的影响

通过室内微宇宙实验系统研究了天津厚蟹(Helice tientsinensis)和双齿围沙蚕(Perinereis aibuhitensis)生物扰动作用下河口沉积物中荧蒽的去除情况。实验结果显示,天津厚蟹扰动组中荧蒽的去除率显著高于沙蚕扰动组(P=0.05)和对照组(P=0.003),其中对表层(0~2 cm)和中层(3~5 cm)的促进效果最为显著;虽然各实验组表层沉积物中荧蒽的去除率均超过50%,但扰动组的去除更快,在36 d时就达最高去除率68%;双齿围沙蚕扰动组底层沉积物中荧蒽的去除率高于厚蟹扰动组和对照组,但差异不显著。研究表明表层沉积物中的荧蒽易去除,厚蟹生物扰动对荧蒽去除有显著促进作用;在距离表层5cm以下的沉积物中荧蒽的持久性增强,但生物扰动作用可促进其去除。     

Impact of food to microorganism ratio and alcohol ethoxylate dosage on methane production in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor

The effects of food to microorganism (F/M) ratio and alcohol ethoxylate (AE) dosage on the methane production potential were investigated in treatment of low-strength wastewater by a submerged anaerobic membrane bioreactor (SAnMBR). The fate of AE and its acute and/or chronic impact on the anaerobic microbes were also analyzed. The results indicated that AE had an inhibitory effect to methane production potential (lag-time depends on the AE dosage) and the negative effect attenuated subsequently and methane production could recover at F/M ratio of 0.088–0.357. VFA measurement proved that AE was degraded into small molecular organic acids and then converted into methane at lower F/M ratio (F/M<0.158). After long-term acclimation, anaerobic microbe could cope with the stress of AE by producing more EPS (extracellular polymeric substances) and SMP (soluble microbial products) due to its self-protection behavior and then enhance its tolerance ability. However, the methane production potential was considerably decreased when AE was present in wastewater at a higher F/M ratio of 1.054. Higher AE amount and F/M ratio may destroy the cell structure of microbe, which lead to the decrease of methane production activity of sludge and methane production potential.

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126kV双断口快速真空断路器仿真研究

快速真空断路器因其动作速度快、可靠性高、动作分散性小等特点,目前多应用于中低压配用电系统。以一种限制变压器励磁涌流的126 kV双断口罐式结构的快速真空断路器为例,采用有限元仿真研究了其电场、磁场、温度场分布。仿真结果表明,采用罐式双断口结构的快速真空断路器的绝缘性能、磁场分布及通流性能均满足设计要求。     

热分析在椰壳活性炭制备过程中的应用

以椰壳炭为原料,水为活化剂,利用同步热重-差热分析（TG—DTA）仪对椰壳炭活化的机理、浸渍时间、反应热效应以及微波辐照对椰壳活性炭制备的影响进行了探讨。实验表明,不同的椰壳炭都有一个吸热脱水失重阶段。随着浸渍时间的增加,活化点、失重率以及相应放热温度区间的上限温度均增加,当浸渍时间由24h延长到48h时,390～998℃失重率由11．001％增加到32．048％,放热温度区间的上限温度由660℃增加为855℃,放热效应有利于水蒸气与椰壳炭在800～900℃高温下的吸热活化反应,同时有利于使水一椰壳炭通过微波辐照迅速达到活化反应温度,为椰壳活性炭的制备提供理论依据。     

斜网-混凝沉淀-A/O工艺处理白卡纸废水

采用斜网+混凝沉淀+A/O工艺处理白卡纸废水,平均CODCr去除率为97·9%,平均SS去除率为99·1%,出水各项指标达到《造纸工业水污染物排放标准》(GB3544-92)一级标准。以斜网装置回收废浆,过水量5~12m3/(m2·h),CODCr去除率52·8%,SS去除率53·7%。回收纤维获益相当于每吨纸节省成本33元,占总成本的2·5%。将剩余污泥回流到沉淀反应池,可降低投药量,节约总运行费用25%,并能减轻二次污染。     

霾污染对输变电设备外绝缘影响的研究进展

为了研究霾污染对电力安全的影响,综述了近年来国内外针对霾污染对输变电设备外绝缘影响的研究进展,总结了影响输变电设备外绝缘的霾天气指标,霾对外绝缘运行状态的危害和绝缘子沉积吸附的研究。展望了大气颗粒物在绝缘子沉积的外场综合观测,霾颗粒沉积物的实验室物理化学分析以及沉降过程的数值模型等亟待解决的问题。     

Invasive species change detection using artificial neural networks and CASI hyperspectral imagery

For monitoring and controlling the extent and intensity of an invasive species, a direct multi-date image classification method was applied in invasive species (salt cedar) change detection in the study area of Lovelock, Nevada. With multidate Compact Airborne Spectrographic Imager (CASI) hyperspectral data sets, two types of hyperspectral CASI input data and two classifiers have been examined and compared for mapping and monitoring the salt cedar change. The two types of input data are all two-date original CASI bands and 12 principal component images (PCs) derived from the two-date CASI images. The two classifiers are an artificial neural network (ANN) and linear discriminant analysis (LDA). The experimental results indicate that (1) the direct multitemporal image classification method applied in land cover change detection is feasible either with original CASI bands or PCs, but a better accuracy was obtained from the CASI PCA transformed data; (2) with the same inputs of 12 PCs, the ANN outperforms the LDA due to the ANN’s non-linear property and ability of handling data without a prerequisite of a certain distribution of the analysis data.     

Assessment of sampling designs to measure riverine fluxes from the Pearl River Delta, China to the South China Sea

The Pearl River Delta (PRD), located in South China and adjacent to the South China Sea, is comprised of a complicated hydrological system; therefore, it was a great challenge to sample adequately to measure fluxes of organic and inorganic materials to the coastal ocean. In this study, several sampling designs, including five-point (the number of sampling points along the river cross-section and three samples collected at the upper, middle, and bottom parts at each vertical line), three-point (at the middle and two other profiles), one-point (at the middle profile), and single-point (upper, middle, or bottom sub-sampling point at the middle profile) methods, were assessed using total organic carbon (TOC) and suspended particulate matter (SPM) as the measurables. Statistical analysis showed that the three- and five-point designs were consistent with one another for TOC measurements (p > 0.05). The three- and one-point sampling methods also yielded similar TOC results (95% of the differences within 10%). Single-point sampling yielded considerably larger errors than the three- and one-point designs, relative to the results from the five-point design, but sampling at the middle sub-point from the middle profile of a river achieved a relatively smaller error than sampling at the upper or bottom sub-point. Comparison of the sampling frequencies of 12 times a year, four times a year, and twice a year indicated that the frequency of twice a year was sufficient to acquire representative TOC data, but larger sample size and higher sampling frequency were deemed necessary to characterize SPM.     

Distribution and sources of organochlorine pesticides in sediments of the Xiangjiang River, south-central China

The Xiangjiang River (XR), the second largest tributary of the Yangtze River, is mainly located in Hunan province in south-central China. Nineteen surface sediment samples (the top 3-cm layer) collected from XR were analyzed to determine the concentrations, distribution, sources, and ecological risk of organochlorine pesticides (OCPs). The concentrations of OCPs were 3.0–29.8 ng/g (dry weight) with a mean of 12.6?±?7.7 ng/g. The widely detected compounds included HCHs, DDTs, HCB, and dieldrin. Overall, the dominant OCPs in the sediments were mainly composed of residual and degradation products, e.g., β-HCH with a mean of 42.2 % in HCHs and p,p′-DDE with a mean of 43.5 % in DDTs, implying that OCPs in the sediments had suffered from long-term aging without fresh inputs in XR. However, there was a high proportion of p,p′-DDT to DDTs in three sites, suggesting that there was use of technical DDT from their surrounding areas at present. The ratios of α-HCH/γ-HCH and p,p′-DDD?+?p,p′-DDE/DDTs increase from the upper reaches to the lower reaches of XR, suggesting sediments enriched with α-HCH and metabolites DDD and DDE during sediment transport process and could be attributed to the transformation of γ-HCH to α-HCH and DDT to DDE or DDD. The assessment of the ecological risk indicates that the OCPs in the sediments of XR have a moderate adverse biological effect on organisms.     

城市绿色发展竞争力评价研究

提出城市绿色发展竞争力概念,探讨环境质量与经济社会发展水平之间的关系,从城市空气环境质量、地表水环境质量、声环境质量、集中式饮用水源地水质和生态环境质量等"硬环境"着手,结合衡量城市经济发展程度的工业GDP指标,构建评价指标体系,用单位工业GDP的环境代价来表征城市绿色发展竞争力水平,并以安徽省省辖市为例进行了实例研究。