Quantifying the nitrogen retention capacity of natural wetlands in the large-scale drainage basin of the Baltic Sea

We estimate the nitrogen retention capacity of natural wetlands in the 1.7 million km² Baltic Sea drainage basin, using a wetland GIS data base. There are approximately 138,000 km² of wetlands (bogs and fens) in the Baltic Sea drainage basin, corresponding to 8% of the area. The input of nitrogen to natural wetlands from atmospheric deposition was estimated to 55,000–161,000 ton y¹. A map of the deposition of both wet and dry nitrogen is presented. The input from the human population was estimated to 255,000 ton y¹ in terms of excretory release in processed sewage water. There may also be leakage from forests and agricultural land into the wetlands. Due to lack of data on hydrology and topography, such potential nitrogen sources are not accounted for here. The capacity of the wetlands to retain the atmospheric deposition of nitrogen was estimated to 34,000–99,000 ton y¹. The potential retention by wetlands was estimated to 57,000–145,000 ton y¹ when the nitrogen input from the human population was added. If drained wetlands were to be restored and their area added to the present wetland area, the nitrogen retention capacity was estimated to increase to 196,000–261,000 ton y¹. Our results indicate that existing natural wetlands in the Baltic Sea drainage basin annually can retain an amount of nitrogen which corresponds to about 5–13% of annual total (natural and anthropogenic) nitrogen emissions entering the Baltic Sea. The ecosystem retention service performed by wetlands accounts for a substantial nitrogen removal, thereby reducing the eutrophication of the Baltic Sea.     

European eel distribution and body condition in a river floodplain: effect of longitudinal and lateral connectivity

Abstract – We studied eel population characteristics (size classes, densities and body condition) in the lower Loire River floodplain (France) to evaluate the effects of longitudinal and lateral gradients. A total of 36 sites were electrofished in June 2005. The sites were grouped first into three river segments according to the distance inland corresponding to a longitudinal gradient and secondly into three lateral connectivity categories. Results indicate that small eels, especially those ≤300 mm, were very abundant downstream but density rapidly decreased upstream. In addition, eels ≤150 mm tended to be most abundant in connected waterbodies. Conversely, the distribution of larger eels was quite uniform across both dimensions. Eel condition decreased upstream. In parallel, in downstream river segment, eels had a lower condition in disconnected waterbodies than in connected ones. Eel specialists still have only a longitudinal perception of eel habitat. Our results suggest that lateral gradients should be also taken into consideration.     

北洛河流域植被恢复的支撑体系

北洛河流域自实行退耕还林政策以来取得了显著成效,但是实践证明植被恢复不是简单的种树种草,必须要根据生态学原则合理种植,既要有技术支撑,还必须考虑到退耕后农民的生存问题,也就是粮食与能源的问题,并要保证农民有一定的经济收入,最后指出要解决好以上问题,必须靠国家政策的支撑。     

银川盆地富硒土地资源研究

在银川盆地首次发现大面积富硒区.该富硒区具有富硒土层厚、硒含量适中、宜于开发利用等特点.富硒土地分布区不仅硒含量高,而且污染有害元素的含量特别低,呈"原生态"的自然状态.初步分析认为银川盆地土地富硒主要与成土母质(母岩)有关.     

近50年来黄河源区水文要素周期性分析及模拟

寒区水文过程是寒区生态系统中的重要环节之一,水热状况将直接决定高寒地区的生态环境状况.用滑动趋势法和墨西哥帽状小波变化分别获取了研究区域近50年来气候变化的年际年代变化及其周期分析,基于青藏高原太阳辐射平衡已有成果,结合联合国粮农组织推荐的彭曼-蒙蒂斯模型,对于达日县可能蒸散发进行了数值模拟.得出以下主要结论:近50年来达日县降水年增加率为0.557 mm/a,而该县最大可能蒸散发量的年增加率为0.132 mm/a,气候总体趋势是由干旱向湿润方向发生转变;达日县年气温序列主要呈现20 a、15 a、7 a和5 a的周期振荡,年降水序列表现为15～20 a和7～8 a的周期振荡;近20年来可能蒸散发呈递减的趋势,汛期序列递减率为0.046 7 mm/a,冬春序列递减率为0.108 4 mm/a.     

沈阳市河流生态建设项目实施建议

近年来,因干旱少雨等自然灾害影响及人类生产活动对环境的破坏,致使一些中小河流生态功能遭到不同程度的破坏。结合沈阳市近年来河流生态建设的实施情况,从工程措施和生物措施两方面详细介绍了针对不同河流状况的生态建设措施,对今后类似工程建设提供借鉴。     

关于大庆市河蟹养殖情况的调查

文章通过对大庆市杜蒙、林句、肇源三县的实地调查，全面介绍了这些地方河蟹养殖的基本情况、突出特点，分析了河蟹养殖发展过程中存在的制约因素和问题，结合大庆市的实际情况，提出了今后发展河蟹养殖业的相关对策建议。     

西藏“一江两河”中部流域河谷沙化草地及其恢复途径探讨

“一江两河”中部流域是西藏沙漠化最为严重的地区之一，草地的沙化对于生态环境的恶化和畜牧业生产造成很大的不利影响。通过对这一地区草地的现状分析，划分了沙化草地类型，并通过示范试验结果分析，探讨了沙化草地恢复的主要措施。     

塔里木河流域“四源一干”生态环境中存在的问题及其成因分析

塔里木河是新疆南疆地区最重要的水源,被誉为“生命之河”。本文章主要针对塔里木河流域“四源一干”生态环境中存在的问题进行了探讨并分析了成因。     

和田河肖塔站水沙特性及水位流量关系的初步研究

和田河属冲积性多泥沙游荡型河流，汛期洪峰与沙峰的暴涨猛落和单一的河床边界组成条件，造成河道水位同流量关系的复杂性和不定性。本文通过对肖塔站三十三年水文系列资料统计分析表明，在时空变化上，和田河河床冲淤变形呈缓慢堆积抬升之势。在论述水位流量关系上，引用相关分析法，根据同流量不同水位出现的不同机率，确定三组相关线，从而较好地阐述了水位同流量的数值对应关系，对今后研究水文数值预报和制定防洪风险留具有一定可借鉴性。