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141.
Samples of whole effluent and effluent suspended solids from a kraft pulp mill and sediments and biota from Jackfish Bay, Lake Superior were analyzed for polychlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs). Tetra-CDFs (4CDF) were consistently detected in whole effluent at levels ranging between 0.3 and 1.3 ng/L. Effluent suspended solids also contained 4CDFs as well as traces of 4CDD, 5CDF, 8CDF and 8CDD. The horizontal sediment distribution suggests that the effluent was the only active source of 4CDF in the area but that 8CDD originated from a more general source such as the atmosphere. An abrupt appearance of 4CDF in the more recent sections of a core profile taken in the bay suggests that an operational change at the pulp mill resulted in the formation of 4CDFs in the mill effluent some time after 1973. Moderate values of 4CDF and low values of 4CDD were found in samples of the shrimp
confirming the presence of an active source of 4CDF in Jackfish Bay. 相似文献
142.
造纸厂废碱液污染土的环境岩土工程研究 总被引:12,自引:0,他引:12
分析了我国造纸厂废碱液的组成成分,受污染土的环境岩土工程特性和污染机理,介绍了污染土地区的岩土工程勘察内容,评价以及一些主要的治理措施。 相似文献
143.
针对造纸废水好氧处理中钙离子(Ca2+)浓度过高影响生化过程和后续膜处理的问题,在实验室模拟废水曝气,研究Ca2+存在对COD去除效果的影响;对厌氧出水进行曝气实验,探究曝气量对钙去除效果的影响;分析表征造纸废水液相中Ca2+浓度和固相污泥中钙的形态,探究造纸废水曝气池中钙的迁移转化规律.结果发现:Ca2+的存在会影响活性污泥的活性,进而导致曝气过程中COD的去除率从71.76%降至36.94%;厌氧出水曝气初始阶段内曝气量越大,Ca2+的去除率越高;Ca2+浓度从厌氧出水到二沉池出水过程中逐渐下降,从游离态转变为CaCO3的结合态而除去. 相似文献
144.
牟海鹰 《中国安全科学学报》2003,13(8):34-37
良好的监控技能对确保飞行安全 ,预防飞行事故发生有十分重要的作用。但由于多方面原因 ,当前的飞行机组监控工作还存在不少问题 ,并成为多起飞行事故主要原因之一。笔者从四方面 ,对民用航空飞行中缺乏良好监控的原因予以分析和说明 :持续有效的监控工作不符合人的本性 ;现行规章制度中未把机组监控技能作为所有机组成员 ,尤其是对辅助操纵者的一项重要任务加以确定 ;现有管理制度与管理观念 ,更多关注行为结果而不是行为发生过程 ;飞行训练中未将其作为重要飞行技能加以训练。笔者强调指出 :采用标准操作程序 ,提高相应飞行阶段的监控技能 ,对不同飞行阶段的工作负荷予以计划和控制、进行工作优先排序 ,加强机组成员间配合 ,在训练中强化监控技能培养等措施 ,有助于改进和增强飞行机组的监控技能 ,确保飞行安全 相似文献
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146.
介绍了稀土磁盘技术在芯棒限动连轧管浊环水处理中的工艺流程、设计参数、处理效果,及其取得的社会效益和应用前景。 相似文献
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Matthew S. Spurlin Brent W. Barker Bradley D. Cross Craig E. Divine 《补救:环境净化治理成本、技术与工艺杂志》2019,29(2):63-73
Nuclear magnetic resonance (NMR) geophysical tools have been widely used in the petroleum exploration industry since the 1960s and have improved significantly in the last two decades. These tools can provide estimates of bulk porosity and fluid content, quantification of bound versus mobile fluids, and estimates of hydraulic conductivity (K). Although the size and cost of oil‐field tools historically limited their use for near‐surface applications, smaller and more economical downhole NMR logging tools are now available for detecting and characterizing the formation water content and K to support environmental and groundwater resource investigations. These tools can be deployed using direct‐push drilling techniques or they can be lowered into existing open borings or wells with nonconductive polyvinyl chloride casings and screens. In many cases, using the tool in existing wells offers a safer and more cost‐effective alternative compared to drilling new boreholes. For environmental investigations, NMR can provide useful high‐resolution quantitative hydrostratigraphic information that can provide additional valuable data to further inform and refine the conceptual site model. This paper highlights several NMR field investigations that demonstrate the viability of this technology as a site characterization tool for near‐surface investigations. NMR measurements were compared to data from lithologic logs, cone penetrometer testing data, and prior field hydraulic tests. Use of NMR to detect vadose zone water, including previously unidentified perched groundwater zones, provided hydrostratigraphic details that could not be gleaned from historical well drilling logs and were used to evaluate drainable pore water versus pore water bound in small pores by capillary forces or electrochemically clay‐bond water. NMR also produced K estimates similar to those from conventional hydraulic tests, but the improved vertical resolution from NMR provided additional information regarding the vertical heterogeneity of the formation along the entire length of the well or borehole. Additionally, bench‐scale tests are presented that confirm the capability for NMR to reliably detect and quantify light nonaqueous phase liquid saturation (specifically diesel fuel and weathered gasoline) in situ. The field tests combined with bench‐scale testing results affirm the applicability and potential for NMR as a practical characterization tool that should increasingly be utilized in environmental investigations. 相似文献