湖泊、池塘的水温模型与最大供冷能力的分析研究

借鉴分层水蓄冷方式,提出利用稳流器装置从水体底部取水、同温层回水的思路,建立了二维竖向水动力水温模型,与实测值的比较表明,该模型可以较准确地反映水体全年自然水温分布状态.利用该水温模型研究了水体的最大供冷能力,分析了供回水温差、气候和水深的影响.     

张家界汨湖地区浅层生物气资源评价及其地质意义

泪湖地区浅层生物气气源岩为第四系未固结——半固结淤泥,埋深小于60．00m。1．56km^2含气范围内,平均气源岩厚度达10．00m以上,生物气生成量2795．17×10^4m^3,资源量为5．60×10^4m^3。生物气分布层段主要为第四系浅层3．00～49．00m,最有利的层段在7．00～20．00m之间;平面上最有利区域分布在汨湖农场东部MQ3井区,平均气源岩厚度为16．7．0m,淤泥有机碳含量1．06％,生气量达1858．02×10^4m^3。其次是泪湖农场MQ2井区,平均气源岩厚度为15．00m,淤泥有机碳含量0．44％,生气量达618．52×10^4m^3。在本区浅层生物气的综合开发利用将极大的提高当地人民的生活质量,有效减少当地工农业生产对煤碳的需求,达到保护当地环境和绿色资源的目的。     

鄱阳湖环湖区域经济建设与生态规划问题研究

鄱阳湖是中国最大的淡水湖泊,随着江西经济的发展,鄱阳湖的污染问题也变得日益严峻,如何合理开发和利用鄱阳湖带动环湖区域经济发展,为江西经济发展作贡献成为了一个急需解决的难题。文章就加强生态建设,全面推进鄱阳湖环区域经济发展做了详细的论述,从水资源、土地资源、气候资源、生物资源、矿产资源、旅游资源的合理开发进行了综合分析,为鄱阳湖环湖区域经济可持续发展提供了理论依据,对鄱阳湖环湖区域经济开发具有指导意义。     

An Energy-Stable High-Order Central Difference Scheme for the Two-Dimensional Shallow Water Equations

An energy-stable high-order central finite difference scheme is derived for the two-dimensional shallow water equations. The scheme is mathematically formulated using the semi-discrete energy method for initial boundary value problems described in Olsson (1995, Math. Comput. 64, 1035–1065): after symmetrizing the equations via a change to entropy variables, the flux derivatives are entropy-split enabling the formulation of a semi-discrete energy estimate. We show experimentally that the entropy-splitting improves the stability properties of the fully discretized equations. Thus, the dependence on numerical dissipation to keep the scheme stable for long term time integrations is reduced relative to the original unsplit form, thereby decreasing non-physical damping of solutions. The numerical dissipation term used with the entropy-split equations is in a form which preserves the semi-discrete energy estimate. A random one-dimensional dam break calculation is performed showing that the shock speed is computed correctly for this particular case, however it is an open question whether the correct shock speed will be computed in generalMSC: 35Q35; 65M12; 65M06Supported in part by the New Zealand Marsden Fund, grant UOA827     

Mortalities of lesser flamingos in Kenyan Rift Valley saline lakes and the implications for sustainable management of the lakes

Lesser flamingo populations in the Kenyan Rift Valley saline lakes respond to changes in phytoplankton species’ composition and densities, behavioural needs, breeding cycles and environmental conditions. The numbers of flamingos are high when the density of blue‐green algae Arthrospira fusiformis (Spirulina platensis) is high, stimulating flamingo courtship and display. The numbers decline when lake levels decline, resulting in low phytoplankton densities and a domination by toxic phytoplankton species. In Kenyan saline Rift Valley lakes, heavy metals, pesticides, algal toxins (microcystin), bacterial infection and malnutrition are plausible causes of lesser flamingo mortalities. The production of cyanotoxins by toxic phytoplankton, as a result of declining lake water levels, could be a major factor contributing to the increased mortality of lesser flamingos. Integrated management of the lakes and their catchments is required to ensure the future well‐being of the lesser flamingos.     

Management of lakes in India

India is home to a wide range of water impoundments located in a diversity of climates, stretching from mountain conditions near the Himalayas in the north, to tropical conditions in the south. The impoundments include natural lakes, wetlands and coastal lagoons, as well as constructed reservoirs and tanks. This paper provides an overview of the lake management in India, focusing on wetlands, reservoirs and tanks. While there has never been a thorough survey of the lakes of India, it is possible to discuss the general conditions in which lake management is currently carried out in India. Overall, lakes all over the country are exhibiting varying degrees of environmental degradation caused by encroachments, eutrophication (from domestic and industrial effluents) and siltation. The high population density ensures that many water bodies are under severe and direct pressure from anthropogenic activities in their catchments. Actions to control and prevent these problems are addressed, with a focus on measures such as public interest litigation, the National Lake Conservation Plan, and the Special Purpose Vehicles. The role of national and international institutions is critiqued. Finally, the issues related to gaps in the knowledge base, delays in restoration, lack of coordination, ineffectiveness of legislation, and the general lack of an integrated approach to management are discussed, and possible solutions to these impediments are explored.     

Effect of lake sediments of different trophic states on alkaline phosphatase activity

Samples of sediments, interstitial water and overlying water were collected monthly under temperature‐controlled conditions to determine the effects of sediment types on the alkaline phosphatase activity (APA) in lake systems. The relationship between the total alkaline phosphatase activity (TAPA) and soluble reactive phosphorus (SRP) concentration also was examined. The study results indicate the variations of TAPA in the overlying water, and the interstitial water in different layers from different sediments was similar over time. They were influenced not only by the phosphate concentrations, but also were correlated with submerged plant and phytoplankton biomass. The direct effects of the sediment types on the APA were not readily obvious. Although the higher APA in sediment was probably responsible for the enzymatic response to the characteristics of sediments, other factors (e.g. growth of submerged plants and phytoplankton) also should be considered. The peak of the maximum velocity of the enzyme reactions (V_max) at deeper sediment layers suggests another stratum in which the enzymatically mediated phosphorus regeneration was active. This finding contributes to our understanding of phosphorus cycling in lake sediments.     

成像测井资料在湖盆沉积研究中的应用

湖盆沉积砂体规模小，分布不稳定，非均质性强，在研究过程中，特别需要运用具有高分辨率、高覆盖率、高直观性特点的成像测井资料。讨论了成像测井资料在湖盆沉积研究中的主要应用：①基于成像测井资料分析常规测井曲线形态对微相分析的可靠性，钟型、箱型曲线代表正韵律的可靠性很好，卵型曲线代表正韵律的可靠性较差，漏斗型曲线并不完全代表反韵律。②识别指相标志。除岩石的颜色外，大部分指相标志都可通过成像测井资料获取。③判断层段的砂体骨架主体。例如在H油田某构造沙三段辫状三角洲前缘亚相的沉积中，根据成像测井资料和常规测井曲线分析沉积韵律，结果是正韵律的数量及厚度远远大于反韵律，从而判断出该层段的砂体骨架主体是水下分流河道砂体，而不是河口坝砂体。④用经过刻度的成像测井资料反映的沉积特征修正地质录井剖面，不仅可以准确识别湖盆沉积的岩性、岩石组合和沉积序列，还可以修正复杂地质层段地质录井资料的失误，恢复正确的岩性剖面及沉积环境。     

湖泊沉积物中污染有机质及碳酸盐的δ13C影响因素分析

摘要：本文以松嫩平原湖泊表层沉积为研究对象。通过对沉积物有机质正构烷烃组分的分析，了解湖泊中有机质的来源和沉积环境。结合湖泊水介质和沉积物特征，综合分析了沉积物有机质和碳酸盐碳同位素组成的影响因素。结果显示出湖泊沉积物中不同有机质类型对碳同位素组成有较大的作用，生物有机质的大量输入使碳酸盐的碳同位素组成明显偏轻，而石油类污染的输入对应于碳酸盐中的碳同位素组成稍偏重。     

Zooplankton partitioning in a tropical alkaline–saline endorheic Lake Nakuru,Kenya: Spatial and temporal trends in relation to the environment

Spatial and temporal zooplankton variations were studied for 1 year in tropical alkaline–saline Lake Nakuru to determine how they partition in the habitat, relative to environmental variables. Monthly samples were collected at 10 sampling sites, with subsurface tows, using 33.5‐μm mesh plankton nets. Physicochemical parameters displayed clear seasonal variations associated with precipitation patterns. Nine species, belonging to two main zooplankton taxonomic groups (ciliates; rotifers), were identified in the samples. Brachionus dimidiatus dominated the samples, accounting for 80% of the total zooplankton abundance. Kruskall–Wallis tests indicated significant (P < 0.05) temporal and spatial variations among all taxonomic groups. Different zooplankton species displayed a clear succession throughout the year. The total abundance of the rotifers and ciliates peaked at sampling sites near inlets during the long rainy seasons, while those in the inshore sites displayed variable succession patterns. Spatiotemporal structure of the zooplankton assemblages, and its correlation with environmental variables, indicated each species displayed distinct niche‐based partitioning. The ciliates niche was associated with increasing soluble reactive phosphorus, total phosphorus and nitrite–nitrogen (NO₂–N) concentrations. Niche partitioning in rotifers was associated with nitrate–nitrogen (NO₃–N), conductivity and pH. These results indicate physical niche separation, even in a small, relatively homogenous lake among species of rotifers and ciliates, providing information from which future changes in their abundance and spatial distributions can be predicted, given continuous water quality changes.