温度对苹果绵蚜生长发育的影响

苹果绵蚜各虫龄的历期随温度的升高而缩短。28℃时, 各虫龄历期最短, 30 ℃时历期稍长, 适宜繁殖温度是25℃左右, 从出生到成蚜再现的发育历期是34.37 天, 最短是9.65天。在不 同温度下的产蚜能力不一, 可能是生长发育受到温度 的抑制。图2表3参4

Effect of body size on growth and energy budget of Nile tilapia, Oreochromis niloticus

A growth trial was conducted at 30 degrees C to investigate the effect of body size on growth and energy budget of Nile tilapia. The average initial body weights of the four size groups tested were 9.3, 34.1, 80.3 and 172.4 g, respectively. Fish were fed to satiation twice a day with a diet containing 35.6% crude protein. Food consumption (C-max: kJ/day) increased with body size (W: g) according to the relationship: Ln C-max = 1.45 + 0.42 LnW. The final body contents of dry matter, crude protein and ash per unit body weight increased with increasing body size while contents of fat and energy were independent of body size. Specific growth rates of wet weight, dry weight, protein and energy decreased as the fish increased in size. Feed efficiencies in wet weigh, dry weight and crude protein decreased with increasing body size, while that of energy remained unchanged. The proportions of energy intake allocated to the various components (faecal energy, excretory energy, heat production and recovered energy) of the energy budget were not significantly affected by body size, and the average budget was: 100IE-18.5(+/- 1.33)FE + 5.9 (+/- 3.09)(ZE + UE) + 49.3(+/- 3.77)HE + 26.3(+/- 6.23)RE, where IE, FE, (ZE + UE), HE and RE represent gross energy intake, faecal energy, excretory (non-faecal) energy loss, heat production and recovered energy (growth), respectively. It is suggested that the decrease in growth rate in larger fish is mainly due to the decrease in relative food intake. (C) 1997 Elsevier Science B.V.

辽宁省生态系统评价与生态功能分区研究

生态系统评价是为了向决策者提供生态系统管理信，息而对生态系统结构、功能进行分析，并根据其变化趋势及驱动力提出相应措施的综合研究过程。生态功能分区是依据生态系统胁迫过程与效应、生态环境质量、敏感性和生态系统服务功能重要性等特征空间分异规律而进行的地理空间分区，目的是辨析区域生态环境问题与生态环境脆弱区和良好区，明确优先保护的生态系统和地区，为生态保护与建设、产业结构调整与优化及区域生态系统分区管理提供科学依据。本研究以辽宁省域生态系统为对象，在生态环境调查的基础上，分析了生态环境状况及变化趋势，进行了生态环境质量、敏感性和生态系统服务功能重要性评价，辨析了存在的生态环境问题及驱动力，明确了生态环境质量、敏感性和生态系统服务功能重要性空间分布格局，然后对辽宁省进行了生态功能区划分，并指出了各功能区生态保护与建设的重点和措施以及产业结构调整与优化的对策和方向研究结果表明，在经济和人口增长的长期胁迫作用下，辽宁省生态环境问题依然严峻，主要表现为：土地退化，地表水污染严重，森林质量下降和功能减弱，草地减少与退化并存，天然湿地萎缩，滩涂和海岸带生境恶化，生物多样性面临威胁，农业面源污染凸显，生态系统抗干扰能力下降，生态灾害加剧。全省生态环境质量超过2／3属于一般以下水平，其中优级面积仅占12.56％，良好级面积占18.71％，主要分布在东部及东南部；一般级面积占34.25％，主要分布在中部、北部和南部；较差级面积占34.48％，主要分布在西部及西北部。全省县级市及县有44个，其中生态环境质量为优的仅有4个市县，占总县数的9.09％；生态环境质量为良的有7个市县，占总县数的15.91％；生态环境质量一般的有19个市县，占总县数的43.18％，生态环境质量较差的有14个市县，占总县数的31.82％。全省处于轻度至高度敏感区域。高度敏感区占34.00％，主要分布在辽东山地丘陵、辽东半岛、辽西低山丘陵、辽西北、柳绕地区和大洼县。辽东山地丘陵、辽东半岛和辽西低山丘陵主要是土壤侵蚀高度敏感。辽西北和柳绕地区主要是土地沙漠化高度敏感。大洼县是土壤盐渍化高度敏感。中度敏感区占能．66％，与高度敏感区相间分布。轻度敏感区占3.34％，零星分布在辽东，在辽西和辽河平原也有少量分布。全省生态服务功能均处于比较重要以上。极重要地区占60.66％，基本分布在辽东、辽西和辽河平原的北部与盘锦滨海地区，辽东主要为水源涵养、生物多样性保护、土壤保持、营养物质保持，辽西主要为土壤保持、生物多样性保护、水源涵养、营养物质保持，辽北主要为土壤保持，盘锦滨海地区主要为生物多样性保护。中等重要地区占37.01%，基本分布在辽河平原，在辽东、辽西也有分布，辽河平原主要为土壤保持、水源涵养，沙漠化控制，辽东和辽西主要为土壤保持，辽西北为沙漠化控制。其它地区为比较重要地区，仅占2.33％，主要分布在辽东和辽河平原，在辽西也有少量分布，主要为土壤保持。在生态系统评价的基础上，首先根据地貌和气候划分出4个生态区，即辽东山地丘陵温带湿润半湿润生态区、辽河平原温带半湿润生态区、辽西低山丘陵温带半湿润生态区、辽南环黄渤海海岸带生态区。在明确生态区的基础上，依据生态系统类型与过程的完整性，以及生态服务功能类型的一致性，划分出21个生态亚区。依据生态环境质量、敏感性及生态服务功能重要性等的一致性，进一步划分出52个生态功能区。

中国青藏高原青稞抗穗发芽资源评价与α-淀粉酶基因的克隆及表达

穗发芽（PHS，preharvest sprouting）是影响禾本科作物生产的重要的灾害之一。收获时期如遇潮湿天气容易导致穗发芽发生。发生穗发芽的种子内部水解酶（主要是α-淀粉酶）活性急剧升高，胚乳贮藏物质开始降解，造成作物产量和品质严重降低。因此，选育低穗发芽风险的品种是当前作物育种工作中面临的重要任务。 青稞(Hordeum vulgare ssp. vulgare)主要分布于青藏高原，自古以来就是青藏高原人民的主要粮食。近年来，由于青稞丰富的营养成分和特有的保健品质、在燃料工业中的潜力以及在啤酒酿造工业中的利用前景，在发达国家日趋受到重视，掀起综合研究利用的热潮。我国拥有占全世界2/3 以上的青稞资源，具有发展青稞产业的得天独厚的条件。然而，由于青稞收获期间恰逢青藏高原雨季来临，常有穗发芽灾害发生，使青稞生产损失巨大。目前对青稞穗发芽研究很少，适用于育种的穗发芽抗性材料相对缺乏，不能很好的满足青稞穗发芽抗性育种的需要。本研究以青藏高原青稞为材料，对其穗发芽抗性的评价指标和体系进行构建，同时筛选青稞抗穗发芽品种并对其抗性进行评价，还利用分子生物学手段对青稞穗发芽抗性的分子机理进行了初步探讨。主要研究结果如下： 1. 本试验以来自于我国青藏高原地区的青稞为材料，对休眠性测定的温度范围进行探讨，并对各种穗发芽抗性测定方法的对青稞的适用性进行评测。通过探讨温度对13 个不同基因型的青稞籽粒发芽和休眠性表达的影响，对筛选青稞抗穗发芽资源的温度条件进行探索，并初步分析了其休眠性表达的机理。在10，15，20，25，30℃的黑暗条件下，选用新收获的13 个青稞品种为材料进行籽粒发芽实验，以发芽指数（GI）评价其休眠性。结果发现，不同品种对温度敏感性不同，其中温度不敏感品种，在各温度条件下均表现很低的休眠性；而温度敏感品种，其休眠性表达受低温抑制，受高温诱导。15℃至25℃是进行青稞休眠性鉴定的较适宜的温度范围。通过对供试材料发芽后的α-淀粉酶活性，发现温度对青稞种子的休眠性表达的影响至少在一定程度上表现在对α-淀粉酶活性的调控上。随后，对分别在马尔康和成都进行种植的34 份青稞穗发芽指数（SI），穗发芽率（SR），籽粒发芽指数（GI）和α-淀粉酶活性（AA）进行了测定和分析，发现它们均受基因型×栽培地点的极显著影响，且四个参数之间具有一定相关性。GI 参数由于其变异系数较低，在不同栽培地点稳定性好，且操作简便，是较可靠和理想的穗发芽评价参数。SI 参数可作为辅助，区别籽粒休眠性相似的材料（基因型）或全面评价材料（基因型）的穗发芽抗性特征。AA 参数稳定性较差，并且检测方法复杂，因此不建议在育种及大量材料筛选和评价时使用。此外，青稞穗发芽抗性受环境影响较大，评价时应考虑到尽可能多的抗性影响因素及其在不同栽培条件下的变异。 2. 对来自青藏高原的青稞穗发芽抗性特征及其与其它农艺性状间的关系进行研究。通过测定穗发芽指数（SI）、籽粒发芽指数（GI）和α-淀粉酶活性（AA），表明113 份青稞材料的穗发芽抗性具有显著差异。SI、GI 和AA 参数的变幅分别为1.00~8.86、0.01~0.97 和0.00~2.76，其均值分别为4.72、0.63 和1.22。根据SI 参数，六个基因型，包括‘XQ9-5’，‘XQ33-9’，‘XQ37-5’，‘XQ42-9’，‘XQ45-7’和‘JCL’被鉴定为抗性品种。综合SI、GI 和AA 参数，可以发现青稞的穗发芽抗性机制包含颖壳等穗部结构的抗性和种子自身的抗性（即种子休眠性），且供试材料中未发现较强的胚休眠品种，除‘XQ45-7’外，所有品种在发芽第四天均能检测出α-淀粉酶活性。穗部结构和种子休眠的抗性机制因基因型不同而不同，在穗发芽抗性中可单独作用或共同作用。农家品种和西藏群体分别比栽培品种和四川群体的穗发芽抗性强，而在不同籽粒颜色的青稞中未发现明显差异。相关性检验发现，青稞的穗发芽抗性，主要是种子休眠性，与百粒重、开花期、成熟期、穗长、芒长和剑叶长呈显著负相关关系，与株高相关性不显著。农艺性状可以作为穗发芽抗性材料选育中的辅助指标。本试验为青稞穗发芽抗性育种研究提供了必要的理论基础和可供使用的亲本材料。 3. α-淀粉酶是由多基因家族编码的蛋白质，在植物种子萌发时高度表达，与植物种子的萌发能力密切相关。在大麦种子发芽时，高等电点α-淀粉酶的活性远大于低等电点的α-淀粉酶。为了研究不同穗发芽抗性青稞品种中编码高等电点α-淀粉酶Amy1 基因结构与抗性间的关系，我们以筛选得到的抗性品种‘XQ32-5’（TR1）、‘XQ37-5’（TR2）、‘XQ45-7’（TR3），易感品种‘97-15’（TS1）、‘9657’（TS2）以及强休眠大麦品种‘SAMSON’（SAM）为材料，对其Amy1 基因的编码区序列进行克隆和结构分析，并对它们推导的氨基酸序列进行比较。结果显示，青稞Amy1 基因具有三个外显子、两个内含子，编码区中有13 个核苷酸变异位点，均位于2、3 号外显子，2 个变异位点位于2 号外显子。SAM 和TS1 分别在2 号外显子相应位置有5 个相同的碱基(GAACT)的插入片段。相应α-淀粉酶氨基酸序列推导发现，所有核苷酸变异中有8 个导致相应氨基酸残基的改变，其余位点为同义突变。青稞Amy1 基因编码区序列品种间相似度高达99%以上，部分序列变异可能与其穗发芽抗性有关。随后，我们又通过SYBR Green 荧光定量技术对该基因在不同发芽时间（1d~7d）的相对表达水平进行了差异性检测。结果发现，7 天内不能检测到SAM 的Amy1 基因表达，5 个青稞品种间的Amy1 基因的相对表达量均随着发芽时间延长而上升，但上升方式有所不同。弱抗品种该基因表达更早，转录本增加速率更大，且在4~5 天可达到平台期。发芽7 天中，抗性品种总转录水平明显低于易感品种。本研究结果表明，青稞Amy1 基因的转录水平是与其穗发芽抗性高度相关。 我国青藏高原青稞，尤其是农家品种的穗发芽抗性具有丰富的变异，蕴藏着穗发芽抗性育种的宝贵资源。本研究为青稞穗发芽抗性育种建立了合理抗性评价体系，筛选出可供育种使用的特殊材料，阐明了农艺性状可辅助穗发芽抗性育种，同时还对穗发芽抗性与α-淀粉酶基因的结构和表达关系进行分析，为青稞穗发芽抗性资源筛选奠定了基础。 Preharvest sprouting (PHS) is a serious problem in crop production. It often takes place when encountering damp, cold conditions at harvest time and results in the decrease of grain quality and great loss of yield by triggering the synthesis of endosperm degrading enzymes (mostly the α-amylase). Therefore, PHS is regarded as an important criterion for crop breeding. In order to minimize the risk of PHS, resistant genotypes are highly required. Hulless barley (Hordeum vulgare ssp. vulgare) is the staple food crop in Qinghai-Tibetan Plateau from of old, where is one of the origin and genetic diversity centers of hulless barley. Recently, interest in hulless barley has been sparked throughout the world due to the demonstrations of its great potential in health food industry and fuel alcohol production. Indeed, hulless barley can also be utilized to produce good quality malt if the appropriate malting conditions are used. In China, overcast and rainy conditions often occur at maturity of hulless barley and cause an adverse on its production and application. PHS resistant genotypes, therefore, are highly required for the hulless barley breeding programs. However, few investigations have been made so far on this issue. The objectives of this study were: 1) to assessment of methods used in testing preharvest sprouting resistance in hulless barley; 2) to evaluate the variability and characteristics of PHS resistance of hulless barley from Qinghai-Tibet Plateau in China; 3) to select potential parents for PHS resistance breeding; 4) to primarily study on the molecular mechanism of PHS resistance of hulless barley. Our results are as followed: 1. We investigated the temperature effects on seed germination and seed dormancy expression of hulless barley, discussed appropriate temperature range for screening of PHS resistant varieties, and analyzed the mechanism of seed dormancy expression of hulless barley. The dormancy level of 13 hulless barley were evaluated by GI (germination index) values calculating by seed germination tests at temperature of 10，15，20，25，30℃ in darkness. There were great differences in temperature sensitivity among these accessions. The insensitive accessions showed low dormancy at any temperature while the dormancy expression of sensitive accessions could be restrained by low temperature and induced by high temperature. The temperature range of 15℃ to 25℃ was workable for estimating of dormancy level of hulless barley according to our data. Analysis of α-amylase activity showed that the temperature effects on seed germination and the expression of seed dormancy be achieved probable via regulating of α-amylase activity. Furthermore, we evaluated the differences in sprouting index (SI), sprouting rate (SR), germination index (GI) and α-amylase activity (AA) between Maerkang and Chengdu among 34 accessions of hulless barley from Qinghai-Tibetan Plateau in China. These PHS sprouting parameters were significantly affected by accession×location, and they had correlation between each other. GI was the most reliable parameter because of its low CV value, good repeatability and simple operation. SI could assist in differentiating between accessions of similar dormancy or overall evaluation of the resistance. AA was bad in repeatability and had relatively complex testing method, therefore, not appropriate for breeding and evaluation and screening of PHS resistant materials. Besides, since PHS resistance of hulless barley was greatly influenced by its growth environment, possibly much influencing factors and variations between cultivated conditions should be considered. 2. In this study, large variation was found among 113 genotypes of hulless barley (Hordeum vulgare ssp.vulgare) from Qinghai-Tibetan Plateau in China, based on the sprouting index (SI), germination index (GI) and α-amylase activity (AA) which derived from sprouting test of intact spikes, germination test of threshed seeds and determination of α-amylase activity, respectively. The range of SI, GI and AA was 1.00~8.86, 0.01~0.97 and 0.00~2.76，the mean was 4.72, 0.63 and 1.22 espectively. Six resistant genotypes, including ‘XQ9-5’, ‘XQ33-9’, ‘XQ37-5’, ‘XQ42-9’, ‘XQ45-7’ and ‘JCL’, were identified based on SI. Integrating the three parameters, it was clear that both hulls and seeds involved in PHS resistance in intact spikes of hulless barley and there was no long-existent embryo dormancy found among the test genotypes. All the genotypes, except ‘XQ45-7’, had detectable α-amylase activity on the 4th day after germination. There was PHS resistance imposed by the hull and seed per se and the two factors can act together or independent of each other. Besides, landraces or Tibet hulless barley had a wider variation and relatively more PHS resistance when compared with cultivars or Sichuan hulless barley. No significant difference was found among hulless barley of different seed colors. The correlation analysis showed PHS resistance was negatively related to hundred grain weight, days to flowering, days to maturity, spike length, awn length and flag length but not related to plant height. This study provides essential information and several donor parents for breeding of resistance to PHS. 3. Alpha-amylase isozymes are encoded by a family of multigenes. They highly express in germinating seeds and is closely related to seed germination ability. In barley germinating seeds, the activity of high pI α-amylase is much higher than low pI α-amylase. The aim of this study was to determine the relationship between preharvest sprouting resistance of hulless barley and the gene structure of Amy1 gene which encodes high pI α-amylase. The coding region and cDNA of Amy1 gene of three resistant accessions, including ‘XQ32-5’ (TR1), ‘XQ37-5’ (TR2), ‘XQ45-7’ (TR3), two susceptible accessions ‘97-15’ (TS1), ‘9657’ (TS2) and one highly dormant barley accession ‘SAMSON’ (SAM) was cloned. Analysis of their DNA sequences revealed there were three exons and two introns in Amy1 gene. Thirteen variable sites were in exon2 and exon3, 2 variable sites were in intron2. SAM and TS1 had a GAACT insert segment in the same site in intron2. Only 8 variable sites caused the change of amino acid residues. There were 99% of similarity between the tested hulless barley and some of the variable sites might be related with preharvest sprouting resistance. Then, we investigated the expression level of Amy1 gene in the 7-day germination test. Results of quantitative real-time PCR indicated that the relative expression trends of Amy1 gene were the same but had significant differences in the increase fashion between hulless barleys and no detectable expression was found in SAM. Susceptible accessions had earlier expression and faster increase and reached the maximum on day 4 ~ day 5. Besides, total transcripts level was found lower in resistant accessions than susceptible accessions. This study indicated that α-amylase activity was highly related to the transcription level of Amy1 gene which not correlated to missense mutation sites. In conclusion, hulless barley, especially the landraces from Qinghai-Tibetan Plateau in China possesses high degree of variation in PHS performance, which indicates the potential of Tibetan hulless barley as a good source for breeding of resistance to PHS. This study provides several donor parents for breeding of resistance to PHS. Our results also demonstrate that agronomic traits may be used as assistants for PHS resistance selection in hulless barley. Besides, analysis of high pI α-amylase coding gene Amy1 revealed the relative high expression of was Amy1 one of the mainly reason of different PHS resistance level in hulless barley.

Structure and acidity of Mo/H-MCM-22 catalysts studied by NMR spectroscopy

A comprehensive study on physical and chemical properties of Mo/MCM-22 bifunctional catalysts has been made by using combined analytic and spectroscopic techniques, such as adsorption, elemental analysis, and Xe-129 and P-31 NMR of adsorbed trialkylphosphine oxide probe molecules. Samples prepared by the impregnation method with Mo loadings ranging from 2-10 wt.% have been examined and the results are compared with that obtained from samples prepared by mechanical mixing using MoO3 or Mo2C as agents. Sample calcination treatment is essential in achieving a well-dispersed metal species in Mo/MCM-22. It was found that, upon initial incorporation, the Mo species tend to inactivate both Bronsted and Lewis sites locate predominantly in the supercages rather than the 10-membered ring channels of MCM-22. However, as the Mo loading exceeds 6 wt.%, the excessive Mo species tend to migrate toward extracrystalline surfaces of the catalyst. A consistent decrease in concentrations of acid sites with increasing Mo loading < 6 wt.% was found, especially for those with higher acid strengths. Upon loading of Mo > 6 wt.%, further decreases in both Bronsted and Lewis acidities were observed. These results provide crucial supports for interpreting the peculiar behaviors previously observed during the conversion of methane to benzene over Mo/MCM-22 catalyst under non-oxidative conditions, in which an optimal performance was achieved with a Mo loading of 6 wt.%. The effects of Mo incorporation on porosity and acidity features of the catalyst are discussed. (C) 2004 Published by Elsevier B.V.

氮和磷在饲养-堆腐环中的循环率及有机肥料养分利用率

A five-year experiment indicated that the average loss rate of N and P in harvested products through a feeding-composting cycle was about 50% and 15%,respectively.Under high yield condition,the amount of recycled N and P from 80% harvested products and through a feeding-composting cycle in farming systems was about 3751 and 814 kghm~(-2),equivalent to 25%34% of N and 32%56% of P from chemical fertilizers applied each year to the systems.The apparent recoveries of N and P in organic manure increased with the prolongation of fertilization,indicating a synergetic residual effect existed,and was 61% and 39% in average in the five-year experiment.The use of nutrients recycled in the farming systems could not only improve soil fertility,but also increase the recoveries of nutrients and reduce the use of chemical fertilizers.

感耦等离子体发射光谱法分析稀土元素的研究进展

近年来,感耦等离子体发射光谱法(ICP-AES)用于分析稀土元素的研究很活跃,实际应用日益广泛,有关基础研究也有一定进展。程介克等对此已有概述,认为ICP-AES日益广泛的应用是近期稀土元素分析化学进展的重要特征之一。本文拟从基体效应、光谱干扰及修正、检出限以及实际应用情况等方面,比较详细地评述感耦等离子体发射光谱法分析稀土元素的研究进展及尚待解决的问题。

高温高压下二辉橄榄岩的阻抗谱实验研究

在1．0～4．0GPa压力、1073～1573K温度和10^-1～10^7Hz频率条件下，利用SARLTON-1260阻抗一增益／相位分析仪，就位测定了二辉橄榄岩的阻抗谱。实验结果表明：二辉橄榄岩的阻抗谱对频率具有很强的依赖性，并从阻抗谱的测试原理(颗粒内部、颗粒边缘、样品与电极间的导电机制)上做出了解释；温度是决定二辉橄榄岩电导率的一个重要物理参数，电导率随着温度的升高而增大，lgσ与1／T之间符合Arrenhius关系式；在高压实验中第一次将压力作为测量二辉橄榄岩电导率重要的约束因素，随着压力的增大，电阻率升高、电导率降低。

贵州红枫湖、百花湖沉积物-水界面营养元素（磷、氮、碳）的生物地球化学作用

富营养化是目前水资源管理的一个主要环境问题。水体中过量的营养元素是引起富营养化的根本原因，其中磷和氮是主要的控制因素。多数湖泊中磷是藻类自然生长的限制因子，因此多年来人们治理富营养化水体的主要策略是减少磷的排放，然而，通过此法成功恢复湖泊生态的例子屈指可数，一个主要的原因就是沉积物中的磷的再释放。因此，沉积物营养元素(尤其是沉积物－水界面上)的生物地球化学过程一直是湖泊科学研究的焦点。本次工作选择贵州的两个人工湖泊—红枫湖、百花湖，通过对磷、氮、碳在沉积物中的化学形态、垂直剖面等方面的研究，结合室内模拟实验和模式计算，揭示了沉积物早期成岩过程中磷、氮、碳的地球化学行为及其潜在的环境效应。尤其是对沉积物磷开展了较深入的研究。红枫湖、百花湖水体中的N／P为46～126，磷是湖泊的限制性营养因子。分析表明，红枫湖、百花湖沉积物中的全磷的平均含量为1300～1500μg.g~(-1)，与其它湖泊相比，红枫湖、百花湖具有较高的磷负荷。根据Ruttenberg提出的化学连续提取法(SEDEX)，可以把沉积物中的磷分为五种形态：(弱)吸附态磷、铁结合态磷、自生磷灰石磷、残留岩屑磷和有机磷。两湖沉积物中以有机磷和铁结合态磷为主，有机磷分别占全磷的60％(红枫湖)和50.3％(百花湖)，铁结合态磷为28.25％(红枫湖)和34％(百花湖)，这在其它湖泊是极少见的，红枫湖、百花湖沉积物磷具有很高的迁移活性。有机物质是沉积物磷的主要载体，沉积物中－部分有机质被保存下来，其余的矿化降解，同时释放出溶解磷(HPO_4~(2-))，这些溶解磷可以扩散到上覆水体为浮游生物吸收利用，或是以其它形态滞留在沉积物中。沉积物孔隙水中NO_3~-、SO_4~(2-)、Fe~(2+)、Mn~(2+)的剖面分布表明，红枫湖、百花湖沉积物最活跃的有机质降解发生在表层2厘米的沉积物内。根据孔隙水HPO_4~(2-)的浓度梯度，可以计算沉积物－水界面HPO_4~(2-)的交换通量(J_s)，红枫湖、百花湖沉积物-水界面磷的扩散通量(J_s)存在明显的季节性变化：在冬春季扩散通量最大，而夏秋季较小，这与传统的认识相反，我们认为这是由于表层沉积物中有机质的矿化降解有关。我们研究了沉积物吸附作用对沉积物磷循环的影响。吸附动力学实验表明，吸附的动力学过程可以用Langmuir或Freundlich方程描述；红枫湖、百花湖沉积物具有很大的理论吸附容量极值(红枫湖的S_m为21.05mgP.g~(-1),百花湖的S_m为15.83mgP.g~(-1));沉积物对磷酸盐的吸附主要是由于其中的未定型的铁氧化物矿物造成的；铁氧化矿物的吸附作用是沉积物中磷滞留的重要机制；经CDB去除铁氧化物处理后，沉积物吸附磷酸根的能力仅为原来的10％。对原状沉积物-界面水柱的释磷实验结果表明：好氧条件下沉积物的溶解磷的释放通量较高，而厌氧条件下相反较低。进一步说明了有机质降解在磷循环中的地位。将沉积物中磷的形态分析数据、孔隙水溶解磷以及吸附盐实验的数据，用于“扩散-平流-反应”模式，结果表明：红枫湖、百花湖沉积物表层有机质(磷)的降解释磷是沉积物-水界面磷交换通量的主要部分，由于沉积物表层易分解有机质的含量较高，铁氧化物的吸附不足以完全阻止沉积物磷酸盐的释放，有机质的氧化降解速率决定了释放通量的大小；而在表层以下的沉积物中铁氧化物的吸附作用是控制孔隙水溶解磷剖面分布的主要因素；红枫湖、百花湖沉积物的整个埋藏历史中(40年)，基本没有稳定自生磷灰石矿物的形成。红枫湖、百花湖沉积物全氮平均为沉积物干重的0.36～0.40％，表层含量为0.69～1.06％，沉积物中的含氮化合物主要85％以上是有机氮，沉积物全氮和有机氮呈现表层富集，随沉积深度增加而减少的剖面特征。红枫湖、百花湖沉积物对固定铵氮的能力较强，固定铵的绝对含量分别为434.05 mg.kg~(-1)和(16.94mg.kg~(-1)，分别相对于总氮含量的13.53％和12.53％。红枫湖、百花湖水体和沉积物孔隙水中氨态氮(NH_4~+)和硝态氮(NO_3~-)的剖面分布表明：在沉积物-水界面上发生着最剧烈的氮循环作用，这也是清除水体氮负荷的最彻底和唯一的机制。沉积物水界面起到向上覆水体的营养供给和对污染水体自然净化的双重功能。红枫湖、百花湖的沉积物柱芯上有机质剖面通常仅表现“降解阶段”和“堆积阶段”，对红枫湖HF980903-1-2柱芯的分析，发现红枫湖沉积物有机质(碳、氮)的降解代谢过程同样包括类似于洱海沉积物的“沉降－降解－堆积”三个阶段，我们认为是样品的分隔精度不足以反映沉积剖面的细节；同时也说明，红枫湖、百花湖沉积物有机质组成中有较多的“新鲜”、活性的组分，它们的快速降解使得沉积物中有机质不能长期保存。研究表明，经过10年堆积埋藏，沉积物有机质大约有35～76％被降解。上层沉积物中(活性)有机质的迅速分解，是引起沉积物－水界面强烈的营养元素循环的重要原因。剖面对比分析显示，红枫湖、百花湖沉积物有机物质分解过程中，有机碳、磷、氮的改造是不同步的，有机碳相对稳定，而含氮化合物和有机磷则相对易于降解。C_(Org): N_(Org): P_(Org)比值的分析结果表明：红枫湖、百花湖沉积物有机质的来源主要是来源于无纤维素植物。较高的C／N、C／P和较低的N／P，反映了小型湖泊受到较多的人为干扰和流域物质输入影响的特点。

透平叶片冷却膜稳定性的实验研究

在水洞中,对透平叶片冷却膜附壁的稳定性进行了显示观察和测量的实验研究。用圆柱和放大的叶片做模型,模拟叶片前缘和叶盆凹面的流动。在流体动力学相似条件下,用色液显示的方法,观察了圆柱上展向喷射角β为30°的冷漠的流动图案;测量了从圆周角θ为10°、20°、25°和40°处喷射的冷膜的临界速比m_(cr)与主流加速度参数K的关系,并得出经验公式;m_(cr)=f(K、β)。测量的叶片凹面上冷膜的m_(cr)与K的关系,有与圆柱凸面上的相近趋势,可作为工程设计的参考依据。

南海北部湾23/25太阳区块海底工程地质调查与评价

<正> 本项成果,是承包美国太阳东方勘探公司任务而完成的。在系统分析总结了南海西部石油公司“南海—503工程地质取芯船”在南海北部湾23/25太阳区块所进行的测深、侧扫声纳、地震声学剖面测量,及4口孔深40米的工程地质浅钻土柱等材料的基础上,详细阐述了