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311.
以聚合氯化铝PAC为混凝剂,纳米SiO2为助凝剂,对含有下列微污染物:十二烷基硫酸钠(SDS)、氨氮(NH3-N)或腐植酸(HA)的高岭土悬浊液进行混凝沉降实验。借助形态学理论、电镜观察与图像分析技术,研究纳米SiO2对微污染物的助凝作用效果、吸附特性与絮体结构的形态学特征。结果表明:(1)在含有HA、SDS、NH3-N的模拟原水中,污染物去除率与浊度去除率的相关性随污染物分子量的增大而增强;(2)纳米SiO3对HA、SDS及NH3-N的助凝吸附效果,随分子量的降低而减弱。纳米SiO2能促使PAC对HA、SDS与NH3-N的去除率分别提高40%~50%、20%~30%和10%~15%;(3)纳米SiO2能促使PAC作用下的絮体粒径增大、密实度和分维值增加、沉速加快。 相似文献
312.
Moens LN Smolders R van der Ven K van Remortel P Del-Favero J De Coen WM 《Chemosphere》2007,67(11):2293-2304
Effluents are a main source of direct and continuous input of pollutants to the aquatic environment, and can cause ecotoxicological effects at different levels of biological organization. Since gene expression responses represent the primary interaction site between environmental contaminants and biota, they provide essential clues to understand how chemical exposure can affect organismal health. The aim of the present study was to investigate the applicability of a microarray approach for unraveling modes of action of whole effluent toxicity and impact assessment. A chronic toxicity test with common carp (Cyprinus carpio) was conducted where fish were exposed to a control and 100% effluent for 21 days under flow-through conditions. Microarray analysis revealed that effluent treatment mainly affected molecular pathways associated with the energy balance of the fish, including changes in carbohydrate and lipid metabolism, as well as digestive enzyme activity. These gene expression responses were in clear agreement with, and provided additional mechanistic information on various cellular and higher level effects observed for the same effluent. Our results demonstrate the benefit of toxicogenomic tools in a “systems toxicology” approach, involving the integration of adverse effects of chemicals and stressors across multiple levels of biological complexity. 相似文献
313.
Luigi Monte 《Ecological modelling》1998,110(3):134
In the present paper a collective model for predicting the migration of dissolved toxic substances through drainage areas is described. The model has been validated using data for 137Cs and 90Sr concentrations in water of some European contaminated rivers following the atmospheric fall-out from the accident at the Chernobyl power plant. It has been demonstrated that the migration rate λ (s−1) of a dissolved toxic substance from a catchment may be evaluated by the following approximate formula: λ=(c ln t+d)/t, where t is the time from a pulse deposition event and the coefficients c and d depend on the characteristics of the substance. It has been shown that the mathematical form of the transfer function (flux of dissolved substance at time t following a single pulse deposition of a pollutant onto the catchment) of a toxic substance from a drainage area is very simple. Moreover, the values of the transfer function parameters are slightly variable despite the large range of characteristics of the catchments here examined. Indeed, the statistical aggregation of competing migration processes can lead to ‘stable’ collective behaviours that are less variable than each single process. 相似文献
314.
ClO2氧化/TiO2复合吸附剂协同体系处理印染废水的实验研究 总被引:1,自引:0,他引:1
利用ClO2 氧化/TiO2 复合吸附剂协同体系对处理实际印染废水进行了实验研究.结果表明,对于COD为750 mg/L、色度为250倍、SS为100 mg/L的1 000 mL印染废水,当溶液pH为4.0、ClO2 用量20 mg/L、TiO2 复合吸附剂用量2.5 g、反应时间和吸附时间分别为2、8 min时,处理后的废水COD<100 mg/L、色度<40倍、SS<70 mg/L,达到了《纺织染整工业水污染物排放标准》(GB 4287-92)排放要求.并对两者的协同机理进行了理论上的探讨. 相似文献
315.
采用大田试验研究专用叶面营养液对主要叶菜的增产效果;并以芥菜为供试叶菜系统研究了专用叶面营养液对叶菜的增产机理。结果表明;专用叶面营养液可明显促进芥菜对N、P、K养分的吸收,提高叶片硝酸还原酶活性、叶绿素含量及光合速率,增加产量和改善品质。专用叶面营养液分别优于这种营养液中的营养物质和生长调节剂。芥菜喷施专用叶面营养液,与对照相比,叶绿素含量、光合速率、硝酸还原酶活性分别增加20.2%、36%、1.201μg/(g·h);平均增产24.6%;Vc、可溶性糖分别增加87mg/kg和1.7g/kg。 相似文献
316.
取代苯甲醛衍生物的定量结构-活性关系(QSAR)研究 总被引:2,自引:0,他引:2
本文研究了反应性化合物取代苯甲醛衍生物对大型蚤(Daphnia magna)的48h急性毒性,建立了定量结构-活性关系模型,探讨了其毒性作用机制,发现其毒性主要取决于笨环上取代基的Hammett电效应常数.模型预测结果与实验结果基本一致 相似文献
317.
This paper examines local perceptions of two international humanitarian organisations, the International Rescue Committee (IRC) and Malteser International, in the eastern Democratic Republic of the Congo (DRC) (formerly known as Zaire). At times, the self‐perception of these organisations differs considerably from the perceptions of local beneficiaries and stakeholders. This study begins by reviewing the current status of research on local perceptions of externally‐introduced humanitarian action. It goes on to discuss the local perceptions of the IRC and Malteser International, as well as the origins of these perceptions, and to show that three different narratives are used by local actors to explain their different perceptions. The paper ends with an examination of the factors that help to account for the differences in perceptions and of the implications of this type of research for humanitarian principles and management, as well as for the study of local perceptions. 相似文献
318.
有效微生物群(EM)抑藻效应研究 总被引:13,自引:1,他引:12
通过细胞液体培养系统地考察了有效微生物群(EM)对3种常见"水华"藻类生长的抑制作用及适宜条件。实验结果表明:EM能显著抑制衣藻、四尾栅裂藻和盘星藻的生长,培养7d时,3种藻类生物量平均降低率分别达46 80%,99 07%和97 17%;培养温度、培养时间、EM投加量及培养基pH等对EM的抑藻作用均有不同程度的影响。EM发挥良好抑藻作用(绿藻)的适宜条件:培养温度为30℃,培养时间≤5d,EM投加量(V(EM)∶V(源水))为1∶1000~1∶10000,培养基pH为6 0~8 0。 相似文献
319.
1989~2005年中国启动地震应急预案的研究 总被引:7,自引:1,他引:6
制定地震应急预案是地震应急的行动纲领。过去重“救”轻“防”,而且“救”的程序也缺少规范。地震应急预案将“防、抗、救一作了规范.对每个职能部门的应急工作都作了部署。全国地区(市)级颁布地震预案267个,县级颁布地震预案1603个。据不完全统计,1989-2005年,全国共计启动地震应急预案56次。其中,1989~1993年年均启动0.8次,1994-1998年2.2次,1999-2003年4.2次,2004~2005年10次。 相似文献
320.
Candice Carr Kelman Chris J. Barton Kyle Whitman Simon Lhoest Derrick M. Anderson Leah R. Gerber 《Conservation biology》2023,37(2):e14039
The knowledge produced by conservation scientists must be actionable in order to address urgent conservation challenges. To understand the process of creating actionable science, we interviewed 71 conservation scientists who had participated in 1 of 3 fellowship programs focused on training scientists to become agents of change. Using a grounded theory approach, we identified 16 activities that these researchers employed to make their scientific products more actionable. Some activities were more common than others and, arguably, more foundational. We organized these activities into 3 nested categories (motivations, strategies, and tactics). Using a co-occurrence matrix, we found that most activities were positively correlated. These correlations allowed us to identify 5 approaches, framed as profiles, to actionable science: the discloser, focused on open access; the educator, focused on science communication; the networker, focused on user needs and building relationships; the collaborator, focused on boundary spanning; and the pluralist, focused on knowledge coproduction resulting in valuable outcomes for all parties. These profiles build on one another in a hierarchy determined by their complexity and level of engagement, their potential to support actionable science, and their proximity to ideal coproduction with knowledge users. Our results provide clear guidance for conservation scientists to generate actionable science to address the global biodiversity conservation challenge. 相似文献