三江平原典型湿地系统湿沉降中氮浓度及沉降量初步研究

2004年7月至2005年6月对三江平原典型湿地系统大气湿沉降的氮浓度及沉降量进行了初步研究。结果表明,各形态氮的月均浓度差别较大且动态变化明显,原因主要与人类活动、降水强度及频次、风向和地理位置有关;各形态氮浓度均存在明显的季节变化,春季最高,秋、冬季次之,夏季最低。春、秋季降水中各形态氮浓度的离散程度较大,原因与降水气团来源复杂性、沙尘和高空污染物输送等因素有关;降水量与各形态氮浓度呈较弱的负相关(p>0.05),NH4 -N与NO3--N、TON呈显著正相关(p<0.05),它们可能具有同源性。NH4 -N与NO3--N的良好相关性与其在液相中的反应有关;生长季降水pH的变化主要与氨挥发有关,非生长季主要与氨挥发减弱、秸秆和化石燃料燃烧以及沙尘输送等因素有关;各形态氮的沉降量具有明显的季节性,春季所占比例最高(4.57kg N/hm2),占60.41%,夏、秋季相近,冬季最低(8.29%);全年TN沉降量为7.57 kgN/hm2,TIN为沉降主体,占84.54%;NH4 -N和NO3--N为TIN沉降主体,分别占TN沉降量的52.58和29.99%。图4,表2,参16。     

基于生态经济学理论与方法的生态补偿量化研究

以生态系统服务和生态足迹的理论和方法为基础,从国家宏观层面建立生态补偿的判定标准、量化模型和计算方法.在此基础上以中国各省份为例,研究中国区域之间的生态补偿量化问题.结果表明:1)生态赤字大小的顺序为东部>中部>西部,而生态系统服务价值贡献顺序恰好相反.2)东部地区该支付的生态补偿总量为439.50×108yuan/a,各省平均为73.25×108yuan/a;中部总量为482.98×108yuan/a,各省平均为40.25×108yuan/a,西部总量158.56×108yuan/a,各省平均为12.20×108yuan/a.建议国家建立生态补偿基金,协调区域生态服务与生态占用的矛盾.     

青藏高原若尔盖盆地草地沙化成因分析及治理对策

根据野外调查与遥感解译,结合前人研究资料,论述了若尔盖盆地沙化草地分布特征,探讨了草地沙化日趋严重的原因,提出了对青藏高原生态研究、长江、黄河上游沙漠化的防治均具有重要意义的治理对策.     

随机激励下藻类生态系统的分岔研究

为了研究随机干扰因素与藻类生态系统稳定性之间的相互关系,运用随机非线性理论中的随机平均法和Oseledec乘性遍历定理研究了浮游动物和浮游植物构成的藻类生态系统的稳定性和分岔特性.通过对稳态概率密度的数值模拟,确定系统会发生随机Hopf分岔.研究结果表明,随机因素可以使系统稳定性发生质的变化.     

基于最大流原理的复杂生态系统分形结构

生态系统具有分形等复杂性特点,一直是学术界关注的热点和难点.而现有的研究大都缺乏深入的动力学机理分析.针对这一空白,本文以一个远离平衡的复杂系统总是努力寻找一种优化过程,使得系统在给定的约束或代价下所获得的广义流最大这个思想出发,从微观动力学角度探讨了生态系统模式的分形长大过程.从尺度变化角度对分形生长思想进行了MATLAB数值模拟佐证.分析了影响分形维数的因素并比较了理论结果与实际例子,进而讨论了在实践中的可能应用.     

海水养殖对海域生态系统的影响及其生物修复

海水养殖业的迅速发展对海域生态系统产生了一系列的严重影响,本文综述了海水养殖带来的营养盐污染及沉积环境变化、药物使用污染、对天然生物的影响等问题.对于海水养殖造成的问题,有着多种治理方式,基于养殖生态系统的生物修复,是近年来新兴的安全有效的修复方法.本文介绍了微生物修复、大型海藻修复、贝-藻修复、人工湿地修复等生物修复方法及其研究进展.随着研究的不断深入,治理的方式也越来越多,但要想从根本上解决海水养殖带来的污染及影响,基于生态系统的海水养殖管理乃是实现海水养殖业可持续发展的关键.     

景观设计的坐标——生态设计

景观的生态性并不是新鲜的概念。无论在什么环境中建造,景观都与自然发生密切的联系。任何与生态过程相协调,尽量使其对环境的影响破坏达到最小的设计形式都称为生态设计。景观与生态设计反映了人类新的美学观和价值观——人与自然的友爱关系。     

南海北部大陆架海洋生态系统Ecopath模型的应用与分析

过度捕捞和环境恶化导致渔业资源和海洋生态系统逆向发展。采用EwE5.1软件,对南海北部大陆架建立Ecopath(生态通道模型)模型。通过各级流量、生物量、生产量、捕捞量、系统总流量以及生态位和混和营养效应等方面的分析,得出营养流通主要有2种途径,肉食鱼类间饵料竞争非常激烈,低值鱼类间具相似的捕食压力,顶级捕食者对大部分鱼类负效应不明显。系统受过度捕捞渔业影响很大,并存在营养级I利用效率低和渔业资源小型化、低值化等不稳定的幼态特征。     

^226Ra evidence for the ecosystem shift over the past 40 years in the North Pacific Subtropical Gyre

Surface seawater was collected for ~(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a declined trend of surface ~(226)Ra concentrations was observed since 1960s, indicating the ecosystem shift in response to global warming. On one side, the enhanced stratification of the upper water column resulting from global warming reduced the ~(226)Ra input from the depth, on the other, the temporal increase of biological production resulting from the climate-related ecosystem structure change strengthened the ~(226)Ra removal from the surface ocean. Both the physical and biological processes resulted in the decrease of surface ~(226)Ra concentrations in the North Pacific Subtropical Gyre. The temporal trend of surface ~(226)Ra concentrations was consistent with the trends of chlorophyll a, silicate, phosphate and primary production previously reported. This study provided ~(226)Ra evidence for the ecosystem shift under global change.     

Ecosystem vulnerability of China under B2 climate scenario in the 21st century

This paper applies climate change scenarios in China based on the SRES assumptions with the help of RCMs projections by PRECIS （providing regional climates for impacts studies） system introduced to China from.the Hadley Centre for Climate Prediction and Research at a high-resolution （50 kmx50 km） over China. This research focuses on B2 scenario of SRES. A biogeochemical model ＂Atmosphere Vegetation Integrated Model （AVIM2）＂ was applied to simulating ecosystem status in the 21st century. Then vulnerability of ecosystems was assessed based on a set of index of mainly net primary production （NPP） of vegetation. Results show that climate change would affect ecosystem of China severely and there would be a worse trend with the lapse of time. The regions where having vulnerable ecological background would have heavier impacts while some regions with better ecological background would also receive serious impacts. Extreme climate even would bring about worse impact on the ecosystems. Open shrub and desert steppe would be the two most affected types. When the extreme events happen, vulnerable ecosystem would extend to part of defoliate broad-leaved forest, woody grassland and evergreen conifer forest. Climate change would not always be negative. It could be of some benefit to cold region during the near-term. However, in view of mid-term to long-term negative impact on ecosystem vulnerability would be enormously.