Phytotoxicity of nitroaromatic energetic compounds freshly amended or weathered and aged in sandy loam soil

The toxicities of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to terrestrial plants alfalfa (Medicago sativa L.), Japanese millet (Echinochloa crusgalli L.), and perennial ryegrass (Lolium perenne L.) were determined in Sassafras sandy loam soil using seedling emergence, fresh shoot, and dry mass measurement endpoints. A 13-week weathering and aging of energetic materials in soils, which included wetting and drying cycles, and exposure to sunlight of individual soil treatments, was incorporated into the study design to better reflect the soil exposure conditions in the field than toxicity determinations in freshly amended soils. Definitive toxicity tests showed that dinitrotoluenes were more phytotoxic for all plant species in freshly amended treatments based on EC20 values for dry shoot ranging from 3 to 24mgkg(-1) compared with values for TNB or TNT ranging from 43 to 62mgkg(-1). Weathering and aging of energetic materials (EMs) in soil significantly decreased the toxicity of TNT, TNB or 2,6-DNT to Japanese millet or ryegrass based on seedling emergence, but significantly increased the toxicity of all four EMs to all three plant species based on shoot growth. Exposure of the three plant species to relatively low concentrations of the four compounds initially stimulated plant growth before the onset of inhibition at greater concentrations (hormesis).     

Removal of polycyclic aromatic hydrocarbons from manufactured gas plant-contaminated soils using sunflower oil: laboratory column experiments

Laboratory column experiments were performed to remove PAHs (polycyclic aromatic hydrocarbons) from two contaminated soils using sunflower oil. Two liters of sunflower oil was added to the top of the columns (33 cm x 21 cm) packed with 1 kg of PAH-contaminated soil. The sunflower oil was applied sequentially in two different ways, i.e. five additions of 400 ml or two additions of 1l. The influence of PAH concentration and the volume of sunflower oil on PAH removal were examined. A soil respiration experiment was carried out and organic carbon contents of the soils were measured to determine degradability of remaining sunflower oil in the soils. Results showed that the sunflower oil was effective in removing PAHs from the two soils, more PAHs were removed by adding sunflower oil in two steps than in five steps, probably because of the slower flow rate in the former method. More than 90% of total PAHs was removed from a heavily contaminated soil (with a total 13 PAH concentration of 4721 mg kg(-1)) using 4 l of sunflower oil. A similar removal efficiency was obtained for another contaminated soil (with a total 13 PAH concentration of 724 mg kg(-1)), while only 2l was needed to give a similar efficiency. Approximately 4-5% of the sunflower oil remained in the soils. Soil respiration curves showed that remaining sunflower oil was degraded by allowing air exchange and supplying with nutrients. Organic carbon content of the soil was restored to original level after 180 d incubation. These results indicated that the sunflower oil had a great capacity to remove PAHs from contaminated soils, and sunflower oil solubilization can be an alternative technique for remediation of PAH contaminated soils.     

Relationship between carbonaceous materials and polychlorinated biphenyls (PCBs) in the sediments of the Danshui River and adjacent coastal areas, Taiwan

Persistent organic pollutants, POPs (e.g., polychlorinated biphenyls) can seriously and deleteriously affect environmental quality and human health. These organic pollutants are exhibiting high affinities to solid phases and thus, quickly end up in sediments. To better understand the role of carbonaceous materials in the transport and distributions of POPs in terrestrial and near-shore environments, concentrations of PCBs and carbonaceous materials (including total organic carbon, black carbon and total carbohydrates), were determined in surface sediments of the Danshui River and nearby coastal areas, Taiwan. Total concentrations of PCBs in the sediments ranged from non-detectable to 83.9 ngg(-1), dry weight, with the maximum value detected near the discharge point of the marine outfall from the Pali Sewage Treatment Plant. These results suggest that the sewage treatment plant has discharged PCBs in the past and the concentrations are still high due to their persistence; alternatively, PCBs are still being discharged in the estuarine and near-shore environment of the Danshui River. Organic carbon and black carbon concentrations correlated well with those of total PCBs in the sediments, suggesting that both organic carbon and black carbon significantly affect the distribution of trace organic pollutants through either post-depositional adsorption, or by co-transport of similar source materials. The field results demonstrate that black carbon and plays an important role in the general distribution of PCBs, while concentrations of some specific PCBs are affected by both black carbon and organic carbon concentrations.     

自然灾害后成人抑郁症危险因素的Meta分析

为了解自然灾害后成人抑郁症发生的危险因素,通过检索PubMed、Embase、Web of Science、中国生物医学文献数据库、中国知网、维普和万方数据库(检索时间跨度为从建库至2021年5月31日),获取关于自然灾害后抑郁症的相关文献,包括病例对照研究、横断面研究和队列研究.文献检索、研究选择和数据提取由2位研究...     

二十世纪以来福建灾害史研究述评

二十世纪以来福建灾害史研究成果显著,在灾害史料整理和专题研究方面都相对系统和完善。随着福建灾害史研究的不断深入,其未来的研究发展趋向更应受到关注与思考。通过回顾与总结福建灾害史的研究范围、研究内容及研究方法,发现其仍具有进一步深化的探索空间,主要体现在拓展灾害研究的时空范围、扩充灾害史料的来源与数量、加强灾荒文本的考辨与解读、构建灾害历史数据库、突破固有的研究模式以及进行多学科的综合研究等方面,而这些发展方向也是此后推进和深化福建灾害史研究值得注意的重要问题。     

开滦集团RMDC管理模式研究

在实现经济体制转变、逐步适应社会主义市场经济体制期间，开滦集团公司企业内部管理暴露出一系列问题。通过问题的分析，综合运用现代管理理论，构建了企业管理模式的框架体系，并结合企业发展历史和现状，研究设计了企业管理模式的重点内容。     

江苏油田实施清洁生产审核中存在的问题及其对策

对江苏油田在清洁生产审核过程中存在的职工对清洁生产认识上的误区、清洁生产审核方法不当、清洁生产目标设置单一、清洁生产验收标准欠规范四个方面的问题进行了剖析,结合企业近年来推行清洁生产积累的经验,在广泛实践的基础上,对存在的问题提出了相应的整改措施,包括:加强职工思想教育,规范清洁生产审核工作,完善审核验收标准,注重开发清洁生产技术,建立清洁生产技术信息系统及技术交流平台。这些措施对提高油田企业实施清洁生产水平具有一定的借鉴作用。     

发展西部特色农业 促进资源优势向经济优势的快速转变

本文在简要分析新形势下西部特色农业优势和劣势的基础上 ,提出了一些西部发展特色农业 ,促进资源优势向经济优势转变的发展对策和政策建议     

待生滑阀异常关闭导致催化裂化装置停车事故分析

针对催化裂化装置待生滑阀突然关闭导致装置停车事故,通过对仪表及系统处理过程进行原因分析,总结了事故的经验教训及防范措施,指出了炼化企业大型设备不但要正确使用,更要精心维护保养,才能确保装置正常平稳运行防患于未然。     

动车组突发事故应急处置现状及对策研究

本文分析了我国铁路突发事件及应急管理的现状,以京哈上行线汽车侵限与D8次旅客列车碰撞事故应急处置为研究对象,研究了动车突发事故及应急处置特点,分析了目前动车组应急管理过程存在的问题,提出了加强预警机制、完善应急预案、增加应急培训演练等提高动车碰撞突发事故应急处置效率的措施。