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991.
赤潮的生物毒性评价初步研究——生物毒性测试方法在一次胶州湾赤潮中的应用 总被引:4,自引:2,他引:4
在2000-07-25-30发生于青岛胶州湾,面积约10km^2的赤潮过程中,于2000-07-26和27日分别采集赤潮现场海水,以三咱标准毒性实验生物黑褐新糠虾(Neomysis awatschensis),卤虫(Artemia salina)和ICR品系小白鼠为实验动物,对胶州湾这次赤潮进行了的毒性研究。结果表明:现场采集的赤潮海水和实验室经f/2培养后藻液对卤虫有急性毒性作用,24h卤虫幼体的存活率分别为83%和73%,对小白鼠的毒性均在相当于STX0.87-1.8μg/L的范围内,而对糠虾没有明显影响。本文同时了赤潮现场海水中的藻类组成与数量,探讨了此次赤潮的毒性来源和致毒机制,提出了对赤潮进行生物毒性评价的观点,并建议有关部门将赤潮毒性测试结果作为一个重要的部分应用于现场赤潮事件报道中。 相似文献
992.
Impacts of land cover change on plant and bird species diversity in Hainan Island,China 总被引:2,自引:0,他引:2
1IntroductionLandcoverchangehasanincreasingimpactonforestecosystemsworldwide.Thedestructionofnativehabitatsisrecognizedasoneo... 相似文献
993.
994.
Hao Guo Zhixiang Zhang Zhi Jiang Mingxia Chen Hisahiro Einag Wenfeng Shangguan 《环境科学学报(英文版)》2020,32(12):196-204
Various manganese oxides (MnOx) prepared via citric acid solution combustion synthesis were applied for catalytic oxidation of benzene. The results showed the ratios of citric acid/manganese nitrate in synthesizing process positively affected the physicochemical properties of MnOx, e.g., BET (Brunauer-Emmett-Teller) surface area, porous structure, reducibility and so on, which were in close relationship with their catalytic performance. Of all the catalysts, the sample prepared at a citric acid/manganese nitrate ratio of 2:1 (C2M1) displayed the best catalytic activity with T90 (the temperature when 90% of benzene was catalytically oxidized) of 212℃. Further investigation showed that C2M1 was Mn2O3 with abundant nano-pores, the largest surface area and the proper ratio of surface Mn4+/Mn3+, resulting in preferable low-temperature reducibility and abundant surface active adsorbed oxygen species. The analysis results of the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) revealed that the benzene was successively oxidized to phenolate, o-benzoquinone, small molecules (such as maleates, acetates, and vinyl), and finally transformed to CO2 and H2O. 相似文献
995.
为研究炭材料调理对污泥电脱水性能及泥饼可燃性的影响,使用改性前后的活性炭和石墨对污泥进行预调理,对调理后的污泥进行电脱水实验,深入解析了炭材料调理前后污泥电脱水行为及泥饼可燃性的变化.研究表明:经炭材料调理后的污泥,阴极电脱水速率提升,相较于其他3种炭材料,石墨调理后的阴极电脱水速率提升最为明显,石墨的投加量5% TSS时,阴极平均脱水速率从0.074g/L上升到0.095g/L.炭材料可以提高污泥体系的电导性和污泥絮体的电泳淌度,使得阴极泥饼孔容有上升的趋势,阴极泥饼孔容从未投加炭材料时的0.1147cm3/g增加到AC-0、AC-1、AC-5、石墨的投加量为20% TSS时的0.119、0.122、0.146、0.157cm3/g;此外,炭材料加入后阴阳两极滤液中溶解有机物DOM和蛋白质组分浓度降低,可以缓解滤布堵塞;污泥电脱水过程中经炭材料调理后可以降低脱离每单位水所需要的能耗,未投加炭材料时去除每单位水所需能耗为6.75kW·h/kg去除水,而当AC-0、AC-1、AC-5、石墨的投加量为20% TSS时,能耗分别降低到5.64、5.22、5.20、5.11kW·h/kg去除水,且泥饼含水率从未投加炭材料时的58%降低至45%,固炭量增加,提高了泥饼的热值和可持续燃烧时间,当石墨的投加量为20% g/gTSS时,泥饼热值提高了17%.有利于后续焚烧资源化利用. 相似文献
996.
目的获得高超声速飞行器翼前缘射流降热机理。方法通过计算流体力学(CFD)方法,针对典型高超声速带翼飞行器开展飞行马赫数为15条件下的射流干扰热环境规律研究,分析无射流翼前缘气动加热特性,确定热流严酷射流开孔区域,分别在翼前缘激波干扰及翼后段布置射流孔,并设计射流流动参数,开展射流总压与来流总压比率在0.002~0.02范围内的流场仿真计算,获得局部流动及表面热流分布特性,针对计算结果进行对比分析。结果随着总压比率逐渐增大,激波干扰以及机翼后段射流孔区域热流均显著降低,降幅达76%~99%。翼中段无射流典型位置总压比率为0.002时热流增高,增幅为11%~24%,随着射流总压增大热流降低,降幅达68%~86%。高射流总压比率局部射流孔前热流增大2倍以上。结论射流影响下降热机理是射流将高温气体推离壁面,局部表面热流显著降低。低射流总压比率亚音速射流作用区域向下游延伸距离短,不会引起局部再附热流增大。高射流总压比率音速射流降热影响向下游明显延伸,增强射流强度可以增加延伸区长度,同时会诱导局部射流孔前再附热流显著增大。 相似文献
997.
Fanhao Song Fengchang Wu Weiying Feng Zhi Tang John P. Giesy Fei Guo Di Shi Xiaofei Liu Ning Qin Baoshan Xing Yingchen Bai 《环境科学学报(英文版)》2018,30(12):116-125
Structural characteristics and proton binding properties of sub-fractions (FA3–FA13) of fulvic acid (FA), eluted stepwise by pyrophosphate buffer were examined by use of fluorescence titration combined with fluorescence regional integration (FRI) and differential fluorescence spectroscopy (DFS). Humic-like (H-L) and fulvic-like (F-L) materials, which accounted for more than 80% of fluorescence response, were dominant in five sub-fractions of FA. Based on FRI analysis, except the response of F-L materials in FA9 and FA13, maximum changes in percent fluorescence response were less than 10% as pH was increased from 2.5 to 11.5. Contents of carboxylic and phenolic groups were compared for fluorescence peaks of FA sub-fractions based on pH-dependent fluorescence derived from DFS. Static quenching was the dominant mechanism for binding of protons by FA sub-fractions. Dissociation constants (pKa) were calculated by use of results of DFS and the modified Stern-Volmer relationship. The pKa of H-L, F-L, tryptophan-like and tyrosine-like materials of FA sub-fractions exhibited ranges of 3.17–4.06, 3.12–3.97, 4.14–4.45 and 4.25–4.76, respectively, for acidic pHs. At basic pHs, values of pKa for corresponding materials were in ranges of 9.71–10.24, 9.62–10.99, 9.67–10.31 and 9.33–10.28, respectively. At acidic pH, protein-like (P-L) materials had greater affinities for protons than did either H-L or F-L materials. The di-carboxylic and phenolic groups were likely predominant sites of protonation for both H-L and F-L materials at both acidic and basic pHs. Amino acid groups were significant factors during proton binding to protein-like materials of FA sub-fractions at basic pH. 相似文献
998.
城市景观规划中的防洪策略--以2002年欧洲特大洪灾为例 总被引:1,自引:1,他引:1
近年来,由于全球变暖、不合理地改造自然、城市化进程加剧以及人们的思想松懈等原因,世界上城市洪灾发生较为频繁,给各国城市和人民带来重大损失。城市防洪已成为城市发展过程中备受关注的问题。为此,以2002年8月欧洲部分国家爆发的特大洪水为例,在分析其原因的基础上,提出了城市景观规划中的防洪策赂,希望它能对我国的城市防洪事业和城市景观规划工作起到借鉴作用。 相似文献
999.
Thetemperatureiscrucialenvironmentalconditionforcrop'sgrowthandtoohighortoolowtemperatureisharmfultocrop'sgrowth.Guangxiliesinthetransitionbeltbetweensubtropicalareaandtropicalareawheretherearefavourableconditionsforplantingcropsandfruitsofsubtropicalandtropicalareas.Especially,inrecentyearswiththeeconomicdevelop mentofcountryandlargelyplantingoffruitsandanti seasonalvegetables,Guangxihasbecomemainfruits producingareaandcrops producingareaintropicalandsubtropicalareas.Thein vadingofcoldwaveinw… 相似文献
1000.