负离子元素杂质破坏模型

探讨了HfO2薄膜中负离子元素杂质破坏模型，并得出薄膜中的杂质主要来源于镀膜材料。用电子束蒸发方法沉积两种不同Cl元素古量的HfO2薄膜，测定薄膜弱吸收和损伤阈值来验证负离子元素破坏模型。结果表明，随着Cl元素含量的增加薄膜的弱吸收增加损伤阈值减小。这主要是因为负离子元素在蒸发过程中形成挥发性的气源中心而产生缺陷，缺陷在激光辐照过程中又形成吸收中心．因此负离子元素的存在将加速薄膜的破坏。

三峡大坝的修建对库区动物的影响

世界上最大的大坝—三峡大坝―于2003年6月正式建成并蓄水，三峡水库的水位由蓄水前的84m上升至蓄水后的139m。三峡大坝的修建与蓄水，已经显著地改变了三峡库区陆地生态系统和水域生态系统的生态环境。三峡大坝的修建将如何影响生活在这一区域（包括陆地和水域）的野生动植物资源，是个亟待解决的问题。 对于陆地生态系统，三峡大坝的修建，使三峡库区的生态环境进一步破碎化（Fragmentation）和岛屿化（Island）。为了了解三峡大坝的修建对三峡库区野生动物所产生的影响，我们选择适应性强且对环境变化敏感的啮齿动物为研究对象，在三峡库区选取两个岛屿（洛碛岛和皇华岛）及其对岸为研究点，在野外调查了啮齿动物的群落组成、种群密度与分布，并用胃容物分析和稳定性同位素分析方法研究了两个研究点优势种啮齿动物的食物来源与组成。结果表明，两个研究点间啮齿动物群落组成有很大差异，这主要是由于啮齿动物分布的地域性差异引起的。在同一个研究点，岛屿上的啮齿动物群落组成与对岸的没有差异，但在岛屿上的啮齿动物种群密度却明显高于其对岸的，这说明随着库区水位的大幅度提升，岛屿的面积急剧减小，使原本栖息在水边的啮齿动物不得不向岛屿的中上部迁移，致使岛屿上的啮齿动物的种群密度迅速增加。啮齿动物的食物来源有四种：C3非豆科植物，C3豆科植物，C4植物及水生生物。不同种啮齿动物的食物种类组成也不同，四川短尾鼩（Anourosorex squamipes）的食物中有水生生物的组成成分，但其它啮齿动物食物中不含水生生物。不同食物来源在啮齿动物的整体食物中所占比例也不同，并呈明显的季节性变化，这种变化与田间的农作物种类密切相关。动物组织的稳定性同位素组成不仅可以示踪动物的食物来源，也反映了动物的生存状况。我们的结果显示：对岸啮齿动物的稳定性同位素组成相对集中，并且不同种啮齿动物间没有重叠。这一方面说明对岸啮齿动物的食物来源相对丰富，啮齿动物可以选择各自喜食食物，在此环境下的啮齿动物种间竞争相对较弱，至少是种间食物竞争较弱。岛屿上啮齿动物的稳定性同位素值分布范围远大于在对岸的，并且种间稳定性同位素组成有明显的重叠部分。稳定性同位素组成的重叠意味着有相似的食物来源，也即栖息生境相似。这说明岛上的啮齿动物种间存在较剧烈的食物竞争关系。在资源限制情况下，多种啮齿动物不得不利用共同的食物来源。换句话说，岛屿化过程将加剧岛屿上啮齿动物的种间竞争。 洛碛岛上的四川短尾鼩因为可以利用水生食物来源，这使得它在岛屿化过程中处于有利地位。随着岛屿化进程的加剧，四川短尾鼩在岛屿上的优势将更加明显。而皇华岛屿上的褐家鼠的食物来源单一，会因岛屿面积的进一步减小，食物来源更加缺乏，它们将不得不改其食物组成或面临消失。而白腹巨鼠的栖息环境靠近江边，将因水位的上升进一步上移，它们的栖息环境与普通田鼠的发生重叠，使得白腹巨鼠与普通田鼠发生栖息地的竞争与食物竞争，并面临更多的人为因素干扰。 对于水域生态系统，长江是我国最大的河流，也是我国淡水鱼类最丰富的区域。三峡大坝的修建已经显著改变了三峡库区的水文特征。为了了解三峡大坝的修建是否会改变三峡库区的有机物组成，并进而影响到三峡库区水生生物的食物来源和组成，我们选择了三个水文特征不同的研究点（洛碛江段、皇华城江段和茅坪江段）调查了三峡库区的常见鱼种类组成，并用稳定性同位素方法研究了三峡库区洪水前后的有机物组成变化与鱼类的食物网模型，用稳定性同位素划分了鱼类食物网结构及鱼类体长与其肌肉δ15N值间的关系。结果表明，三峡大坝的修建，已经显著改变了皇华城和茅坪江段的水文特征，同时也“干扰”了生活在这一区域的鱼类。适应于流水环境的鱼类在库区回水处和大坝附近几乎消失，而喜欢静态环境的其它鱼类却得到极大的发展，例如鲢鱼（H. molitrix）和草鱼（ C. idellus）。 洪水前后，三峡库区的有机物组成成分有明显改变。洪水前，水中有机物主要以河流自身生产力产生的有机物为主（浮游植物、藻类等）;洪水后，水中有机物主要以外来有机物为主（陆地植物、土壤有机物和从上游带来的有机物）。对于三个食物网模型：河流连续体模型（RCC）、脉冲模型（FPC）和河流生产力模型（RPM），河流生产力模型能更好的解释三峡库区的水生生物的食物来源，即三峡库区的水生生物的食物主要来源于河流自身生产力产生的有机物。但外来有机物作为水生生物的一种辅助食物来源，在洪水期间起到不可忽视的作用。 在本研究中，鱼类体长与其δ15N值间的关系与选取鱼的种类有关，比如南方大口鲇（Silurus asotus）的体长与其肌肉的δ15N值呈明显负相关关系（R2≈0.5），而鱖鱼（Siniperca）、铜鱼（Coreius guichenoti）和草鱼（Ctenopharyngodon idellus）的体长与其肌肉的δ15N值却呈正相关关系。 三峡库区常见鱼类主要以杂食性和广普性鱼类为主，食物网结构十分复杂。通过胃容物分析和稳定性同位素分析，三峡库区水生生物营养级间的判别值约为3.1‰。依据鱼类肌肉的δ15N值，三峡库区的常见鱼类可以划分为四个营养级：草食性鱼类（herbivorous fish）、初级杂食性鱼类（1ºomnivorous fish）、次级杂食性鱼类（2ºomnivorous fish）和食鱼性鱼类（piscivorous fish）。营养级间没有明确的分界限，鱼类的营养级从2到4.8，是连续分布的营养级结构，从而更真实的反映了自然界中动物的捕食关系和在食物网中的位置。 自然丰度变化的稳定性同位素(Stable isotope)作为一种天然的示踪物，在动物生态学上已经得到广泛应用。动物的稳定性同位素可以清楚的示踪动物的食物来源、食物组成、栖息地情况和生存状况等多种信息，结合传统的胃容物分析，或其它的粪便分析、储藏物分析等，稳定性同位素技术在动物生态学研究方面必将得到更广泛的应用。

Temporal and Spatial Distributions of Rotifers in Xiangxi Bay of the Three Gorges Reservoir, China

From July 2003 to June 2005, investigations of rotifer temporal and spatial distributions were carried out in a bay of the Three Gorges Reservoir, Xiangxi Bay, which is the downstream segment of the Xiangxi River and the nearest bay to the Three Gorges Reservoir dam in Hubei Province, China. Thirteen sampling sites were selected. The results revealed a high species diversity, with 76 species, and 14 dominant species; i.e., Polyarthra vulgaris, Keratella cochlearis, Keratella valga, Synchaeta tremula, Synchaeta stylata, Trichocerca lophoessa, Trichocerca pusilla, Brachionus angularis, Brachionus calyciflorus, Brachionus forficula forficula, Ascomorpha ovalis, Conochilus unicornis, Ploesoma truncatum and Anuraeopsis fissa. After the first year of the reservoir impoundment, the rotifer community was dominated by ten species; one year later it was dominated by eight species. The community in 2003/2004 was dissimilar to that in 2004/2005, which resulted from the succession of the dominant species. The rotifer community exhibited a patchy distribution, with significant heterogeneity observed along the longitudinal axis. All rotifer communities could be divided into three groups, corresponding to the riverine, the transition and the lacustrine zone, respectively.

Effects of damming on population sustainability of Chinese sturgeon, Acipenser sinensis: evaluation of optimal conservation measures

The numbers of spawning sites for Chinese sturgeon have been drastically reduced since the construction of the Gezhouba Dam across the Yangtze River. This dam has blocked migration of Chinese sturgeon to their historic spawning ground causing a significant decline of the Chinese sturgeon population. We conducted a VORTEX population viability analysis to estimate the sustainability of the population and to quantify the efficiency of current and alternative conservation procedures. The model predicted the observed decline of Chinese sturgeon, resulting from the effect of the Gezhouba Dam. These simulations demonstrated the potential interest of two conservation measures: increasing spawning area and reducing predation on sturgeon eggs. The simulations also demonstrated that the actual restocking program is not sufficient to sustain sturgeon population as the artificial reproduction program induce the loss of more wild mature adults that the recruitment expected by the artificial reproduction.

Using drift nets to capture early life stages and monitor spawning of the Yangtze River Chinese sturgeon (Acipenser sinensis)

P>A sampling system for capturing sturgeon eggs using a D-shaped bottom anchored drift net was used to capture early life stages (ELS) of Chinese sturgeon, Acipenser sinensis, and monitor annual spawning success at Yichang on the Yangtze River, 1996-2004, before and just after the Three Gorges Dam began operation. Captured were 96 875 ELS (early life stages: eggs, yolk-sac larvae = eleuthero embryos, and larvae); most were eggs and only 2477 were yolk-sac larvae. Most ELS were captured in the main river channel and inside the bend at the Yichang spawning reach. Yolk-sac larvae were captured for a maximum of 3 days after hatching began, indicating quick dispersal downstream. The back-calculated day of egg fertilization over the eight years indicated a maximum spawning window of 23 days (20 October-10 November). Spawning in all years was restricted temporally, occurred mostly at night and during one or two spawning periods, each lasting several days. The brief temporal spawning window may reduce egg predation by opportunistic predators by flooding the river bottom with millions of eggs. During 1996-2002, the percentage of fertilized eggs in an annual 20-egg sample was between 63.5 to 94.1%; however, in 2003 the percentage fertilized was only 23.8%. This sudden decline may be related to the altered environmental conditions at Yichang caused by operation of the Three Gorges Dam. Further studies are needed to monitor spawning and changes in egg fertilization in this threatened population.

Determination of PAH, PCB, and OCP in water from the Three Gorges Reservoir accumulated by semipermeable membrane devices (SPMD)

Bioavailable water concentrations of polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) were measured in the water column from Three Gorges Reservoir (TGR) collected in May 2008 using semipermeable membrane devices (SPMDs). The sampling sites spanned the whole reservoir from the upstream Chongqing to the great dam covering more than 600 km long distance with water flow velocities ranging from <0.05 to 1.5 m s(-1). This is the first experience of SPMD application in the biggest reservoir in the world. The results of water sampling rates based on performance reference compounds (PRC) were tested to be significantly correlated with water flow velocities in the big river. Results of back-calculated aqueous concentrations based on PRC showed obvious regional variations of PAH, PCB and OCP levels in the reservoir. Total PAH ranged from 13.8 to 97.2 ng L-1, with the higher concentrations occurring in the region of upstream and near the dam. Phenanthrene, fluoranthene, pyrene and chrysene were the predominant PAH compounds in TGR water. Total PCB ranged from 0.08 to 0.51 ng L-1, with the highest one occurring in the region near the dam. PCB 28, 52, 101, 138, 153, 180, 118 were the most abundant PCB congeners in the water. The total OCP ranged from 2.33 to 3.60 ng L-1 and the levels showed homogenous distribution in the whole reservoir. HCH, DDT and HCB, PeCB were the major compounds of OCP fingerprints. Based on water quality criteria, the TGR water could be designated as being polluted by HCB and PAH. Data on PAH, PCB and OCP concentrations found in this survey can be used as reference levels for future POP monitoring programmes in TGR. (C) 2009 Elsevier Ltd. All rights reserved.

Macroinvertebrate community structure in Three-Gorges Reservoir, China

We investigated the macroinvertebrate community structure in Three-Gorges Reservoir during a three-year period after the reservoir became operational. Comparison with data of previous authors obtained before the damming showed that the benthic community changed drastically in the reservoir. Oligochaetes and chironomids dominate the present community. An apparent annual cycle in the benthic community (expressed as richness, density and community type) was found in the second year, lagging one year behind the annual cycle of transparency. After the second year, a Nais-Polypedilum community type, occurring in winter and spring with low inflow discharge and high transparency, was followed by a Limnodrilus community type that occurred in autumn and summer under contrasting conditions. Despite river regulation and damming, it appeared that macroinvertebrates in subtropical canyon-shaped reservoirs remained influenced by floods.

Annual variations of biotic integrity in the upper Yangtze River using an adapted index of biotic integrity (IBI)

Adaptive modification and use of Karr's index of biotic integrity (IBI) for the upper Yangtze River, including 12 metrics in five categories, have typically occurred in line with the data collected by 6-year commercial fisheries investigation. These investigations were undertaken annually in four sections of the Upper Yangtze main channel between 1997 and 2002. These four monitoring sections (Yibin - YB, Hejiang - HJ, Mudong - MD, and Yichang - YC) were selected because they represent the part of the river that will be covering a 1000 kin stretch that includes the future Three Gorges Reservoir (TGR), upstream of the Three Gorges Dam (TGD), an area influenced by the construction of TGD. in addition, historical data were used to show changes in the watershed by comparison with field investigations recently. The biotic integrity of the four sections were calculated and classified into different levels annually for recognizing its spatial and temporal variations. It was observed that IBI scores were becoming lower diminishingly since 1997 in all the four sections. Because all the data were collected before the impoundment of the Three Gorges Reservoir, it is obvious that human activities, especially over-fishing, must be crucial factor instead of damming in the upper Yangtze River in that period. (C) 2008 Published by Elsevier Ltd.

Polymorphic microsatellites in largemouth bronze gudgeon (Coreius guichenoti) developed from repeat-enriched libraries and cross-species amplifications

Largemouth bronze gudgeon (Coreius guichenoti) is a medium-sized fish endemic from the upper Yangtze River of China and its survival is threatened by the construction of the Three Gorges Dam. This study reports 20 new polymorphic microsatellites from a repeat-enriched genomic library with a mean number allele of 5.2, and observed and expected heterozygosities ranging from 0.035 to 1, and from 0.13 to 0.917, respectively. In a cross-species amplification test, nine of the 37 tested loci were found to be also polymorphic in a congeneric species, brass gudgeon (C. heterodon). In addition, other four loci from common carp (Cyprinus carpio) were also polymorphic in C. guichenoti. Out of these 24 polymorphic microsatellites, only three loci significantly deviated from Hardy-Weinberg equilibrium in the sampled population (P < 0.0025), and all pairwise tests for linkage disequilibrium among loci were nonsignificant after applying sequential Bonferroni correction (P > 0.0026). These novel microsatellites provide sufficient levels of polymorphism for studies on population genetics and conservation in C. guichenoti and its related species.

Distribution of phytoplankton in the Three-Gorge Reservoir during rainy and dry seasons

After damming of the Yangtze River, in order to explore the impacts of the Three-Gorge Dam (TGD) on the aquatic ecosystem, phytoplankton composition, abundance and biomass spatial distribution were studied in the Three-Gorge Reservoir (TGR), and the closest upstream anabranch Xiangxi River, which is 38 kin away from the Three-Gorge Dam (TGD) during August (rainy season) 2004 and April (dry season) 2005. In surveys, 6 transects (2 downstream and 4 cross-stream) and 25 stations have been investigated and 314 samples were collected from the surface to the river bed with water samplers. In TGR, 63 taxa and 60 taxa were identified in the rainy and dry seasons, respectively. In the Xiangxi River, 39 taxa were observed in the rainy and dry seasons. Algal blooms occurred in the Xiangxi River and at the influx region of the Yangtze and Xiangxi in both seasons, but had not occurred prior to damming. In the rainy season, the dominant species was Chroomonas acuta with 1.84 x 10(7) cells l(-1), and in the dry season the dominant species were Asterionella formosa and Cryptomonas ovata with 1.34 x 10(7) cells l(-1) and 1.79 x 10(6) cells(.)l(-1), respectively. In the main channel of TGR, there were no significant correlations between phytoplankton abundance and the concentrations of the main soluble nutrients. In the Xiangxi River, significant negative correlations were observed between phytoplankton abundance and nitrate (Spearman, p < 0.01, n=21), phosphate (Spearman, p < 0.05, n=21) and silicate (Spearman, p < 0.01, n=21) in the rainy season, and similar correlations were also observed with nitrate (Spearman, p < 0.05, n=28) and silicate (Speannan, p < 0.01, n=28), but not with phosphate in the dry season. Since the damming of the Yangtze River, eutrophication in the anabranch within the backwater has occurred and become severe, and the frequency of algal bloom within TGR and anabranches is expected to increase. (c) 2006 Elsevier B.V. All rights reserved.

The research of phosphorus of Xiangxi River nearby the Three Gorges, China

The Xiangxi River is the first middling tributary of the Changjiang River near the Three Gorges Dam. The River is subject to phosphorus pollution mainly from industrial wastewater. As the water quality of the Xiangxi River could directly influence the water quality of the Three Gorges Reservoir, the research on phosphorus levels and its change in the sediment profile of the Xiangxi River could provide useful information in the dynamic changes in the system, thereby offering options for mitigative measures. Water and sediment samples from lower reaches of Xiangxi River were collected and the different forms of phosphorus in sediments of the Xiangxi River were studied. The concentrations of total phosphorus in sediment ranged from 757.67 to 1438.54 mg/kg. Inorganic phosphorus concentrations ranged from 684.63 to 1055.58 mg/kg. Phosphorus contamination was serious in some parts of the Xiangxi River. With an average concentration of 635.17 mg/kg, calcium-bound phosphorus is the main form among different inorganic phosphorus forms. Labile phosphorus and iron/aluminum-bound phosphorus measured 3.40, 0.05and 35.28 mg/kg, respectively. The mobilization potential of phosphorus of sediments was studied through adsorption and release experiments. The equilibrium concentration of phosphorus adsorption and release was around 0.1 mg/L. The initial concentrations of phosphorus in the overlying water and the sediments have obvious effect on phosphorus mobilization potential. In addition, the release rate of phosphorus in sediment increased with water depth.

Population genetic structure of an endemic cyprinid fish, Ancherythroculter nigrocauda, in the upper reaches of the Yangtze River and its implication for conservation

Ancherythroculter nigrocauda is a cyprinid fish endemic to the upper reaches of the Yangtze River, which has been reported to have 2 or 3 chambers to its air bladder. Morphological studies showed no differences between individuals with different types of air bladder, but did demonstrate geographical differences from different sources. After the completion of the Three Gorges Dam, it was expected that the population of this species would decrease, but artificial breeding and stocking is under consideration to protect this species from extinction. In the present study, mtDNA cytochrome b gene sequences were determined and analyzed for A. nigrocauda samples of different morphotypes and sources to identify their genetic differentiations, and thereby guide plans for the artificial propagation and conservation of this species. Haplotype diversity index values (h) and nucleotide diversity values (pi) for all the populations were found to be high indicating their high level genetic diversity. An analysis of molecular variance identified no differentiation among the studied populations. Therefore, we suggested that the individuals of different morphological types and geographical sources belong to the same species. To maintain its high level genetic diversity, it mill he necessary to use large and diverse sources of parental fish for artificial reproduction.

Aquatic resource conservation - The first Yangtze finless porpoise successfully born in captivity

Background. As the sole freshwater subspecies of finless porpoise (Neophocaena phocaenoides), the Yangtze finless porpoise (N. p. asiaeorientalis) lives only in the middle and lower reaches of the Yangtze River and its appended Poyang and Dongting Lakes. As a result of human activity on the river, including over and illegal fishing, pollution, transportation and dam construction, the population of Yangtze finless porpoises has been steadily and rapidly decreasing during the past several decades, which leads the animal to be endangered. Methods. For saving this unique animal from extinction, three corresponding measures, in situ conservation, ex situ conservation, and intensifying breeding research in captivity, were proposed and have been implemented since the 1980s. Results. After successfully rearing the animals in captivity for almost nine years, the first Yangtze finless porpoise was successfully born in captivity on July 5, 2005. The calf is male, with a body length of 69 cm. This is the first freshwater cetacean ever born in captivity. Conclusion. The successful birth of this calf confirms that it is possible to breed the Yangtze finless porpoise in captivity. Furthermore, this will greatly benefit the conservation efforts, and also greatly bolster our on-going efforts to study the reproductive biology of these animals. Recommendation. More studies and efforts are expected to establish a sustainable, captive colony of the Yangtze finless porpoise, which will not only greatly expand our knowledge about the reproduction biology of this animal, but also help to redeem the wild population through a careful yearly 'soft releasing' process.

Spawning areas and early development of long spiky-head carp (Luciobrama macrocephalus) in the Yangtze River and Pearl River, China

The spawning areas and early development of long spiky-head carp, Luciobrama macrocephalus (Lacepede), an endemic fish species in China, were investigated in the Yangtze River and Pearl River of central and southeastern China between 1961 and 1993. The potamodromous fish migrated upstream to spawn between May and July as the floodwater began to rise. The water-hardened eggs drifted down the river, and the embryos and larvae developed in the course of drifting. The spawning areas of the fish were widely found in the upper and middle main channels and large tributaries. Two large dams (Gezhouba dam and Danjiangkou dam) did not significantly impact on the reproduction of the fish. Fifty stages of the early development from one cell to the juvenile with fully formed fins were observed and characterized pictorially. The larvae of long spiky-head carp could be distinguished from the larvae of other co-occurring species by counting the number of somites and comparing the proportion of sizes of eye to otic capsule.