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51.
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研究了不同浓度的植物生长物质 ,即 6 苄氨基嘌呤 (6 BA)、2 ,4 二氯笨氧乙酸 (2 ,4 D)对微绿球藻Nannochlorisoculata的生长和代谢影响 ,结果表明 :6 BA和 2 ,4 D在 0 1~ 1 0mg·L 1的实验浓度范围内 ,对微绿球藻的生长、干重、叶绿素a含量、光合作用强度和呼吸作用强度都有一定的促进作用 ,可作为微绿球藻的生长调节剂。6 BA的最佳质量浓度为 0 5mg·L 1;2 ,4 D的最佳质量浓度为 4 0mg·L 1。 相似文献
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1 INTRODUCTION The introduction of invasive marine species into new environments by ship’s ballast water, by attaching to ships’ hulls or via other vectors has been recognized as one of the four major threats to the world’s oceans by Global Environment… 相似文献
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北京市大气颗粒物中全氟烷基化合物的粒径分布特征 总被引:2,自引:1,他引:1
人为排放的持久性有机污染物倾向于在细级大气颗粒物中富集,但目前国内外关于大气颗粒物中全氟烷基化合物(PFASs)粒径分布在不同国家地区有显著差异,而在我国北京地区PFASs在不同粒径大气颗粒物中的富集能力尚不清楚。本文采用五级大流量主动分级采样器采集了北京市大气颗粒物样品,利用超声萃取结合高效液相色谱-电喷雾负电离源串联质谱测定PFASs含量,探讨了该地区大气颗粒物中PFASs的浓度水平和粒径分布特征,以及大气颗粒物浓度变化对PFASs浓度变化的影响。结果表明:研究区∑PFASs范围为10. 1~62. 9 pg/m3,76. 4%~83. 8%的PFASs集中分布在PM2. 5颗粒物中,其中含量较高的PFOA、PFNA和PFDA在0. 25μm细颗粒物中占比最高,分别为26. 3%~43. 7%、30. 3%~68. 6%和30. 6%~49. 7%; PFOS在0. 25μm细颗粒物中没有检出,主要分布在1~2. 5μm和0. 25~1μm颗粒物中。此外,研究发现北京市霾天大气颗粒物中∑PFASs为晴天的3. 5倍,且不同粒径大气颗粒物浓度变化对PFASs各化合物表现出不同的富集能力,其中PFOA、PFOS、PFNA和PFDA等中链PFASs更易富集。 相似文献
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CHEN Di YUAN JianPing XU ShiPing ZHOU XiaoGang ZHANG Yan XU XiaoMing ZOU ZhiWen ZHANG GuRen & WANG JiangHai State Key Laboratory of Bio-control College of Life Sciences Sun Yat-Sen University Guangzhou China School of Marine Sciences Guangzhou State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou R & D Center Guangzhou Enenta Electrical Equipment Co. Ltd Guangzhou ... 《中国科学D辑(英文版)》2009,(5)
Two types of Hepialus larvae with different diets were distinguished in the Sejila Mountain,Tibetan Plateau based on the stable carbon isotope data of the host Hepialus larva of Cordyceps sinensis and its closely adjacent tender plant roots and humus fractions.Type I is the larva chiefly fed by soil humus,and characterized by the δ 13C values of -22.6‰ to-23.4‰,and more than -23.4‰ in its heads.Type II is the larva chiefly fed by tender plant roots,and characterized by the δ 13C values of-24.6‰ to -27.6‰,an... 相似文献
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W. Jaeschke T. Salkowski J. P. Dierssen J. T. Trümbach U. Krischke A. Günther 《Journal of Atmospheric Chemistry》1999,34(3):291-319
During two measuring campaigns in early spring 1994 and 1995 (March/April) and one campaign in summer 1994, measurements of ozone, PAN, sulfur dioxide, nitric acid, and particulate nitrate, sulfate, and ammonium (only 1995) were recorded in the Arctic. Observations were made by aircraft at various sites in the eastern and western Arctic. Ozone concentrations showed a steady increase with altitude both in spring and summer. During five flights in springtime, low ozone events (LOEs) could be observed near the surface and up to altitudes of 2000 m. SO2 background concentrations, ranging from detection limit (0.5 nmol/m3) to 5 nmol/m3, were observed during both spring and summer. Distinct maxima up to 55 nmol/m3 in lower altitudes were only obtained in springtime. Concentrations of the organic nitrate PAN were within a similar range as those of the inorganic nitrate HNO3 during spring campaigns. In contrast, concentrations of particulate nitrate were one half an order of magnitude lower. HNO3 concentrations increased significantly with altitude. Evidently, HNO3 was intruded from the stratosphere into the troposphere. Sulfate concentrations ranged between 5 and 30 nmol/m3; ammonium concentrations were obtained within a range from 10 to 50 nmol/m3. 相似文献
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Characterization of humic substances in salt marsh soils under sea rush (Juncus maritimus) 总被引:2,自引:1,他引:1
C. Santín M. Gonzlez-Prez X.L. Otero P. Vidal-Torrado F. Macías M.. lvarez 《Estuarine, Coastal and Shelf Science》2008,79(3):541-548
Humic substances (HS) from salt marsh soils were characterized and the relationships among HS composition and some geochemical factors were analysed. For this, three salt marshes with the same vegetation cover (Juncus maritimus), but with different geochemical characteristics, were selected. The qualitative characterization of the soil humic acids and fulvic acids was carried out by elemental analysis, FTIR spectroscopy, fluorescence spectroscopy and VACP/MAS 13C NMR spectroscopy.HS from salt marsh soils under sea rush (Juncus maritimus) displayed some shared characteristics such as low degree of humification, low aromatic content and high proportion of labile compounds, mainly polysaccharides and proteins. However, although the three salt marsh soils under study were covered by the same type of vegetation, the HS showed some important differences. HS composition was found to be determined not only by the nature of the original organic material, but also by environmental factors such as soil texture, redox conditions and tidal influence. In general, an increase in the humification process appeared to be related to aerobic conditions and predominance of sand in the mineral fraction of the soil, while the preservation of labile organic compounds may be associated with low redox potential values and fine soil texture. 相似文献
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盐胁迫对爪哇伪枝藻(Scytonema javanicum)生理生化特性的影响 总被引:14,自引:7,他引:14
研究了盐胁迫对荒漠生物结皮中的先锋藻类———S.javanicum的生理生化特性的影响。S.javanicum对盐胁迫很敏感,在较低盐浓度时光合作用活性已很低;色素分析表明,盐胁迫对类胡萝卜素的吸收值影响较大,对Scytonemin色素则较小。从对数生长期开始,其胞外总糖、胞外聚合物(Extracellularpolymericsubstance,EPS)和蛋白质浓度增高,并在稳定期和衰亡期达到最大。随盐浓度升高,盐胁迫显著抑制其生长,生物量产量下降,但单位生物量(μgChla)胞外聚合物各组份的产量增加,其中蛋白质的含量增加更显著。胞内还原性糖含量随盐浓度升高而升高,并在0.1mol·L-1时达最大;脯氨酸含量则呈V形变化。盐胁迫下胞外聚合物、胞内蔗糖、水溶性糖和还原性糖的大量积累,改变了胞内外物质浓度,说明糖类通过改变其代谢方式,在渗透调节上起着重要的作用。 相似文献