模拟增温与UV-B 辐射增强对云杉种子萌发和幼苗生长的影响

臭氧层损耗导致的地球表面UV-B辐射增强以及温室气体增多引起的气候变暖是当今两大全球环境问题。UV-B辐射增强和气候变暖对陆地植物和生态系统产生深远影响，并已成为全球变化研究的重要议题。作为世界第三极的青藏高原，UV-B 辐射增强以及气候变暖现象尤为突出。本试验所在林区是青藏高原东缘的主要林区，具有大面积的亚高山人工针叶成熟林，在全球变化背景下该森林的天然更新潜力如何是急待回答的重要问题。基于此，本研究围绕森林树种的种子和幼苗这一更新的重要阶段，开展了气候变暖、UV-B辐射增强和联合胁迫对云杉种子萌发及幼苗定居影响的研究，旨在全球变化背景下，探讨全球变暖、UV-B 辐射增强和联合胁迫是否对西南地区大面积人工亚高山针叶林更新的种子萌发和幼苗定居阶段产生影响。 本文以青藏高原东缘亚高山针叶林主要树种云杉为研究对象，研究云杉种子萌发及幼苗的生长和生理对UV-B辐射增强与气候变暖的响应。采用UV-B荧光灯（UV-lamp）来模拟增强的UV-B 辐射，此外，采用开顶式有机玻璃罩（OTCs）来模拟气候变暖。本试验包括四个处理：（1）大气UV-B 辐射+大气温度（C）；（2）大气UV-B 辐射+模拟气候变暖（W���；（3）增强的UV-B辐射+大气温度（U）；（4）增强的UV-B辐射+模拟气候变暖（U+W���。 根据本试验结果，UV-B辐射增强对云杉种子萌发没有显著影响，它对萌发云杉幼苗的影响主要体现在幼叶展开以后。根据两年的试验结果，增强的UV-B辐射降低了云杉幼苗抗氧化酶活性，降低了抗氧化物质的含量，此外，造成了膜质的过氧化，表现为MDA在针叶中的积累。增强的UV-B照射处理萌发云杉幼苗两年后，幼苗的生长受到显著抑制。我们的结果显示，OTCs分别提高了空气（10 cm）和土壤（5 cm）温度1.74℃和0.94 ℃。增温显著地促进了云杉种子提前萌发，提高了萌发速率和萌发比率，而且，明显地促进了幼苗的生长，表现为株高和生物量累积的显著增长。此外增温还有利于云杉幼苗根的伸长生长以及生物量的累积，这可以使云杉幼苗更好地利用土壤中的水分和营养元素。 根据本试验结果，温度升高显著地促进了增强UV-B辐射下云杉萌发幼苗的生长，这说明，温度升高缓解了UV-B辐射增强对云杉萌发幼苗的负面影响。这种缓解作用可能是温度升高对UV-B辐射增强处理下幼苗的抗氧化系统活性改善的结果。温度升高还缓解了高UV-B辐射对云杉幼苗根生长的抑制作用，这也可能是增温缓解伤害的原因之一。此外，根据我们的试验结果，增温与UV-B辐射增强联合作用（U+W���下云杉萌发幼苗的生长状况好于大气温度与大气UV-B辐射联合（C）处理，表现为株高、地径、根长和生物量积累均高于C处理，因此可以推断，UV-B辐射增强与气候变暖同时存在对萌发幼苗在两年之内的生长没有产生抑制作用，也就是说，气候变暖的缓解作用完全弥补了UV-B辐射增强的有害作用。 同样，增强的UV-B辐射显著影响了云杉幼苗的光合作用，表现为净光合速率（Pn）和表观量子效率（Φ）的提高，此外，根据我们的试验结果，它还造成了PSII的光抑制。增强的UV-B辐射显著抑制了云杉幼苗对营养元素的吸收，表现为大量营养元素、碳、钙、镁和锌含量的降低，但是，它却显著促进了铁在植株体内的积累。增温显著地提高了净光合速率，但是，它对光系统II（PSII）的光化学效率影响不大。温度升高缓解了UV-B增强对云杉幼苗光合作用的伤害，表现为净光合速率、表观量子效率以及PSII光化学效率的提高。此外，温度升高还缓解了UV-B辐射增强对离子吸收的抑制作用。 Enhanced UV-B radiation due to the reduction of O3 layer and global warming induced by increased greenhouse gases in the air have become the two pressing aspects of global climate changes. Moreover, enhanced UV-B radiation and warming have profound and long-term impacts on terrestrial plants and ecosystems, and the studies focusing on the two factors have attracted many attentions. Qinghai-Tibetan Plateau is the third in elevation in the world, and enhanced UV-B radiation and climate warming are especially prominent in this region. Our research located in the main forest belt in the eastern Qinghai-Tibetan Plateau where large areas of subalpine coniferous forests distributed. Based on that, we carried out a research to study the effects of enhanced UV-B radiation and climate warming on seed germination and seedlings growth of seedlings which are the important basic stage in forest regeneration. This research was arranged by a complete factorial design and included two factors (UV-B radiation and temperature) with two levels. The UV-lamps were used to manipulate the supplemental UV-B radiation and open-top chambers (OTCs) were adopted to increase temperature. The four treatments were: (1) C, ambient UV-B without warming; (2) U, enhanced UV-B without warming; (3) W, ambient UV-B with OTCs warming; (4) U+W, enhanced UV-B with OTCs warming. The main results were exhibited as follows: 1. Based on our results in this research, OTCs increased temperature on average 1.74℃ in air (10 cm above ground) and 0.92 ℃ in soil (5 cm beneath ground). Furthermore, OTCs also slightly reduced soil moisture and relative air humidity, however, the differences was not statistically significant. 2. Our results showed that enhanced UV-B had no significant effects on the seeds germination of P. asperata. Enhanced UV-B affected sprouts of P. asperata until the needles unfolded. During two years, enhanced UV-B inhibited the efficiency of the antioxidant defense systems, and as a result, it induced oxidant stress and the accumulation of MDA in needles. After two years of exposure to enhanced UV-B, the growth of P. asperata sprouts was markedly restrained compared with those under ambient UV-B radiation and temperature (C). Warming significantly stimulated the germination speed and increased the germination rate of P. asperata seeds. In the next place, it prominently facilitated the growth of P. asperata sprouts, represented as improvements in stem elongation and biomass accumulation. Furthermore, warming also increased root growth of P. asperata sprouts, which could made sprouts more efficient to use water and nutrient elements in soil. In this research, warming alleviated the deleterious effects of enhanced UV-B on P. asperata sprouts. It markedly stimulated the growth of P. asperata sprouts exposed to enhanced UV-B. The ease effects of warming on the abilities of the antioxidant defense systems might account for its amending effects on growth. After two years of exposure to enhanced UV-B radiation and warming, the growth of P. asperata sprouts was better than those under ambient UV-B radiation without warming (C), which could be seen from the higher plant height, basal diameter, root length and total biomass accumulation compared with C. 3. Enhanced UV-B radiation significantly influenced the photosynthesis processes of two-year old P. asperata seedlings. Our results showed that enhanced UV-B reduced the net photosynthetic rate (Pn) and the apparent quantum efficiency (Φ), and induced photoinhibition of photosynthetic system II (PSII). Enhanced UV-B significantly decreased the concentration of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg) and zinc (Zn), however, it increased the accumulation of iron (Fe) in the whole plant of P. asperata seedlings. Warming significantly stimulated Pn of P. asperata seedlings but it had no prominent impacts on the photochemical efficiency of PSII. In our research, warming also alleviated the harmful effects of enhanced UV-B on photosynthesis and absorption of ions of P. asperata seedlings. It increased Pn, Φ and the photochemical efficiency of PSII in seedlings exposed to enhanced UV-B. Moreover, warming also increased the absorption of ions of the seedlings exposed to enhanced UV-B radiation.

Rigorous transmittance analysis of a sub-wavelength Sb thin film lens

We quantitatively analysed the factors contributing to the optical transmission enhancement of a sub-wavelength Sb thin film lens, using the finite-difference time-domain (FDTD) method. The results show that the transmission enhancement of the dielectric with a Gaussian distributed refractive index loaded in a sub-wavelength circular hole is not only due to the high refractive index dielectric, but also due to the specific distributions of refractive index. It is the first study about the effects of the refractive index distribution on the transmission of a sub-wavelength aperture. This kind of lens has practical applications in the very small aperture lasers and for near-field optical storage and lithography.

异叶苣苔属系统学和进化研究——兼论尖舌苣苔族的系统发育

异叶苣苔属(Whytockia)隶属于苦苣苔科(Gesneriaceae)、尖舌苣苔族(Klugieae)．70年代以来，该属作为Klugieae中最原始的类群才逐渐被人们所认识，并被认为是解决Klugieae系统发育问题的关键类群，但到目前为止，对该属变异式样及系统发育的认识仍然极其有限．鉴于上述原因，本文结合蜡叶标本和大量的野外观察和采集，从形态学、维管束的结构和分化，形态发生和细胞学等方面，进行异叶苣苔属的系统学和进化研究，并兼论尖舌苣苔族的系统发育． 1．通过对异叶苣苔属大量性状的仔细观察和比较，本文选择了34个性状，并分析了他们的变异式样及其形成原因，为进一步的系统学研究提供依据． 2．地上茎的形态发生研究揭示出异叶苣苔属植物的顶芽完全受到抑制，位于小型叶腋的侧芽萌发，从而替代顶芽生长，地上茎的不分枝是位于大型叶腋的腋芽受到抑制所致，该研究纠正了前人的观察错误． 3．花序及花的形态发生过程表明，异叶苣苔属的花序呈对花从花序轴内侧二列式连续发生，没有任何分枝和附属物．花各部分的发生顺序基本上呈向心式，但在花冠和雄蕊原基之间则为离心式发生．花萼和花冠原基的发生及发育顺序均呈下降式，从而使花萼和花冠在芽中呈下降覆瓦状排列，退化雄蕊是由发育停滞所致．雌蕊的两个心皮在形态发生过程中由离生到合生，该属具中轴胎座的二室子房起源于两个离生心皮的近轴面内卷式愈合，柱头从离生到合生决定于个体发育中愈合部向上推进的程度． 4．为了澄清性状演化极性这一关键问题、本文作了花部器官解剖以及心皮维管束结构及分化过程的研究，结果表明，该属花梗和花萼中均具有分泌道和雄蕊束从中柱独立分出，同独叶苣苔属(Monophyllaea)十分相似：花盘低且薄并且没有维管束，以及子房壁维管束具有不同来源而区别于尖舌苣苔族(Klugieae)中的其它类群．异叶苣苔属的心皮结合程度和胎座形态可分为三种类型，即A型：心皮结合部的中轴区膨大，但四个瓣片的上部分离、B型：除中轴区膨大外，四个瓣片也成对愈合，胎座呈锚形、C型：中轴区不膨大，四个瓣片完全分离，子房上部一室．前者保留了较多的叶性，可能是该属乃至尖舌苣苔族中最原始心皮及胎座形态．后二者代表着两个相反的演化趋势． 5．本文首次报道了异叶苣苔属的染色体数目和核型，染色体数目均为2n＝18，x＝9．核型分别是2A或3A．核型的演化趋势，即从对称到不对称和随体的丢失同外部形态的变异密切相关。 6．深入地比较和分析了异叶苣苔属和其他类群的关系以及性状的演化趋势，并运用分支分析方法，重建属的系统发育． 7．生态、地理分布和演化的研究表明：异叶苣苔属的多样化中心分别是云南东南部和滇、贵、川交界区域，起源于第三纪或更早期的古热带湿润性森林植物区系，起源地可能是两个现代多样化中心所连接的整个区域，即：滇东南至滇贵川交界区域． 8．本文对异叶苣苔属进行全面的分类学修订，包括7个种，其中一个新种，新组合1个种和一个变种、根据该属的系统发育式样，在属下新设两个组．系统排列如下： 异叶苣苔属Whytockia W. W. Smith 组1：异叶苣苔组Sect. Whytockia Y. Z. Wang sect. nov. 1．河口异叶苣苔W. hekouensis Y. Z. Wang 2．毕节异叶苣苔W. bijieensis Y. Z. Wang, sp. nov. 3．异叶苣苔W. chiritiflora (Oliv.) W.W. Smith 4．峨眉异叶苣苔W. wilsonii (A. Weber) Y. Z. Wang, stat. nov. 5．紫红异叶苣苔W. purpurascens Y. Z. Wang 组2：台湾异叶苣苔组Sect. Synstigma Y. Z. Wang, sect. nov. 6．白花异叶苣苔W. tsiangiana (Hand.-Mazz) A. Weber 7．台湾异叶苣苔W. sasakii (Hayata)B．L．Burtt. 9．在异叶苣苔属系统学和进化研究的基础上，结合前人工作，本文进一步探讨尖舌苣苔族的系统发育．大量的证据充分显示出异叶苣苔属和圆果苣苔属分别是Klugieae最原始的类群，该族中的尖舌苣苔属(Rhynchoglossum)，盾座苣苔属(Epithema)和独叶苣苔属(Mono phyllaea)，可能是从Whytockia植物的早期类群直接演化而来，十字苣苔属(Stauranthera)和Loxonia也可能直接或间接来自Gyrogyne植物的早期类群．尖舌苣苔族植物可能起源于亚洲大陆或更准确地说，中国西南部地区，在随后的演化过程中，经过分化、迁移，逐渐形成广布于南亚、东南亚及太平洋岛屿至西非、中美洲的现代地理分布式样。

PCDD/F-s, PCBs, HCHs and HCB in sediments and soils of Ya-Er lake area in China: Results on residual levels and correlation to the organic carbon and particle size

Sediments and soils collected from the Ya-Er Lake area in China were analysed for the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyl (PCBs), hexachlorocyclohexane (HCHs) and hexachlorobenzene (HCB). The results indicated the main pollution problems in the Ya-Er Lake area, which was heavily polluted by HCHs and chlorobenzenes, now is dominantly polluted by PCDD/Fs, PCBs and HCB. The occurrence of PCDD/Fs and PCBs with relatively high levels of HpCDDs, OCDD and low chlorinated-substituted PCBs, is attributed to the discharge of waste water and biodegradation. The vertical distributions of HCH-residues are related with the content of organic carbon and particle size. Copyright (C) 1996 Elsevier Science Ltd

INFLUENCE OF LINEAR ALKYLBENZENE SULFONATE (LAS) AS ORGANIC COSOLVENT ON LEACHING BEHAVIOR OF PCDD/FS FROM FLY-ASH AND SOIL

The leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was measured in soil and standard fly ash column eluted with pure water and linear alkylbenzene sulfonate (LAS)- water. The data obtained were used to evaluate the leachability of PCDD/Fs from waste dump like incineration residual slag and fly ash deposition. The leaching rate was shown to be increased significantly by using LAS water. The leachate contents of PCDD/Fs were above their known water solubility. Concentration of PCDD/Fs in the leachates as well as the relative leaching (calculated on the fly ash content) increased with increasing chlorinating degree and decreasing water solubility. LAS above the critical micelle concentration (CMC) probably enhances PCDD/Fs solubility.

Zinc phthalocyanine (ZnPc) incorporated into silicon matrix grown by plasma enhanced chemical vapor deposition (PECVD)

Hybrid composites composed of zinc phthalocyanine embedded in silicon matrixes have attracted attention because of the potential for solar energy conversion. We produce hybrid composites by thermal evaporation for the plithalocyanine and PECVD (Plasma Enhanced Chemical Vapor Deposition) for the silicon matrix. Deposition of ZnPc/a-Si(amorphous silicon) composites was achieved in a sequential manner. The compound films were characterized by optical transmittance spectra and photoconductivity measurement. The optical transmittance measurements were carried out in the visible region (500 - 800 nm). Compared to pure silicon film, the photosensitivity of compound functional films was enhanced by one order of magnitude. This demonstrates the Si sensitized by adding ZnPc.

Multiple expansions of C-4 plant biomass in East Asia since 7 Ma coupled with strengthened monsoon circulation

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