An integrated river basin-coast-sea modelling scenario for nitrogen management in coastal waters

Linked river basin and coastal water models were applied to analyse the effects of an optimal nitrogen management scenario in the Oder/Odra river basin on water quality in the Oder (Szczecin) Lagoon and the Pomeranian Bay (Baltic Sea). This scenario would reduce nitrogen loads into the coastal waters by about 35%, a level which is similar to the load of the late 1960’s. During summer the primary production and algae biomass in the Oder estuary is limited by nitrogen, which makes a nitrogen management reasonable. The comparison of the late 1960’s and the mid 1990’s shows that an optimal nitrogen management has positive effects on coastal water quality and algae biomass. However, this realistic nitrogen reduction scenario would not ensure a good coastal water quality according to the European Water Framework Directive. A good water quality in the river will not be sufficient to ensure a good water quality in the lagoon. Nitrogen load reductions bear the risk of increased potentially toxic, blue-green algae blooms, especially in the Baltic coastal sea. However, to reach water quality improvements in lagoons and inner coastal waters, nitrogen cuts are necessary. A mere focus on phosphorus is not sufficient.     

FOCUS: A pilot study for national-scale critical loads development in the United States

The development and use of critical loads of air pollutant deposition in the U.S. is gaining momentum, and recent research efforts in the U.S. have produced valuable data for calculating critical loads. Critical loads are used to quantify the levels of air pollutants that are expected to impact forest health, soil fertility, aquatic biota condition, and other ecosystem responses. In addition, model refinements for improving critical loads estimates, and maps for illustrating critical loads for acidification and nitrogen saturation and eutrophication resulting from excess nutrient nitrogen, have been developed at various scales. However, prior to the effort described here, no cohesive process existed to provide a national-scale critical loads database and maps as a unified product representing all U.S. ecosystems. The FOCUS (Focal Center Utility Study) Project was initiated to coordinate the development and implementation of a clear, consistent, repeatable process for calculating and mapping critical loads within the U.S. In the FOCUS Phase I Pilot Study, empirical and calculated critical loads data for the U.S. were synthesized from dozens of regional and national-scale monitoring networks, research projects and publically available databases following an approach similar to that used in Europe. The United Nations Economic Commission for Europe (UNECE), through its International Cooperative Programme on Modelling and Mapping of Critical Levels & Loads and Air Pollution Effects, Risks and Trends (ICP-M&M) collects, analyzes and maps critical loads data. Countries participating in the Convention on Long-range Transboundary Air Pollution (CLRTAP) use a Critical Loads “Focal Center” in each country to serve as the point of contact for submitting regional and national-scale critical loads data to the ICP-M&M. One of the purposes of this study was to develop a foundation for interacting with other Focal Centers by assembling critical loads data, creating a database, establishing modeling protocols, and developing infrastructure within the U.S to report and update critical loads on a national scale. Because the U.S. does not currently have an officially designated Focal Center, critical loads data were provided as an informal, unofficial submission to the Coordination Center for Effects (CCE) of the ICP-M&M in March 2011, in the interest of international cooperation and exchange of information on the effects of atmospheric deposition of pollutants on ecosystems. We envision that these data will enable U.S. scientists, land managers, and environmental policymakers to enter into a productive and meaningful dialogue within the US, and also with the international scientific community on methods for estimating, calculating, mapping, interpreting, and refining critical loads for the effects of acidification and excess nutrient nitrogen on terrestrial and aquatic ecosystems. This paper describes the process used to develop national-scale critical loads in the U.S., summarizes the FOCUS Phase I approach and database development effort, and presents some initial national-scale critical loads mapping products.     

三峡水库支流回水区富营养化时空分布特征

为了解三峡水库175m水位蓄水后库区支流回水区富营养化现状,探索支流回水区富营养化时空变化规律,在三峡库区支流回水区开展了富营养化普查和监测。结果表明,库区支流总磷浓度为0.035~0.65 mg/L,平均浓度为0.157 mg/L,总氮浓度为0.681~5.690 mg/L,平均浓度为2.037mg/L,远远高于湖库水体出现富营养化的总磷和总氮临界浓度0.02、0.2 m g/L,库区支流营养盐条件适宜藻类生长。在每年4~9月的春季、盛夏和夏秋之交的非暴雨时段,当气温和光照适宜,支流回水核心区富营养化现象明显,出现藻类"疯长"的水华现象,但受气温变化影响明显,库区的富营养化现象仍是间歇的,局部的。     

利用水生植物改善北京动物园水环境的研究初探

近年来，北京动物园的水体出现严重的富营养化问题，为了净化水环境，本课题采用了水生植物净化水体的生态工程方法进行了研究。研究结果表明，利用水生植物不仅能净化北京动物园水体，而且还有利于营造水上园林景观和水禽创造适宜的生存环境。从单一水生植物的净化作用上看，水葫芦的净化效果最好，次之为睡莲和野生荷花。人工种植的荷上对较差；多种水生植物的组合更有利于植物在净化作用上的优势互补，从而能始终保持较好的净化效果。此外，试验还发现香蒲的适生水深为0.3-0.4m。     

平原河网地区非点源污染分析

在流域水环境中，非点源污染已成为首要污染源，其研究正成为业内人士关注的重要课题。文中分析了平源河网地区非点源污染研究的现状、进展和防治途径。     

太湖水体富营养化的演变及研究进展

结合多年来对太湖的实地调查研究及相关文献资料分析，综述太湖近几十年水体体富营养化演变趋势，其主要表现为N，P营养盐的增加，水华的频繁显发，富营养化程度日益加剧等，并就近期开展的太湖营养化及其防治的研究作了介绍。     

山仔水库水质富营养化防治对策

通过对山仔水库水质富营养化现状及成因分析，研究探讨恢复系统良性循环的措施和对策，提出防治对策建议。     

福州西湖水体富营养化现象分析（Ⅲ） Ⅲ、浮游植物群落结构

湖泊浮游植物的种类组成和数量不仅反映湖泊水体富营养水平，还直接影响到湖泊的水质状况。1999年夏至2000年春对福州西湖浮游植物群落结构 监测结果显示，福州西湖浮游植物种类丰富，但密度过大。采取有力措施，减少营养盐输入量， 是改善西湖富营养现状的当务之急。     

Stable-isotope probing of bacterial community for dissolved inorganic carbon utilization in Microcystis aeruginosa-dominated eutrophic water

Dissolved inorganic carbon (DIC) is an important source of carbon in aquatic ecosystems, especially under conditions of increased frequency of cyanobacterial bloom. However, the importance of bacteria in direct or indirect utilization of DIC has been widely overlooked in eutrophic freshwater. To identify the functional bacteria that can actively utilize DIC in eutrophic freshwater during cyanobacterial bloom, stable-isotope probing (SIP) experiments were conducted on eutrophic river water with or without inoculation with cyanobacteria (Microcystis aeruginosa). Our 16S rRNA sequencing results revealed the significance of Betaproteobacteria, with similar relative abundance as Alphaproteobacteria, in the active assimilation of H¹³CO₃^? into their DNA directly or indirectly, which include autotrophic genera Betaproteobacterial ammonia-oxidizing bacteria. Other bacterial groups containing autotrophic members, e.g. Planctomycetes and Nitrospira, also presented higher abundance among free-living bacteria in water without cyanobacteria. Microcystis aggregates showed a preference for some specific bacterial members that may utilize H¹³CO₃^? metabolized by Microcystis as organic matter, e.g. Bacteroidetes (Cytophagales, Sphingobacteriales), and microcystin-degrading bacteria Betaproteobacteria (Paucibacter/Burkholderiaceae). This study provides some valuable information regarding the functional bacteria that can actively utilize DIC in eutrophic freshwater.     

In-situ observations of internal dissolved heavy metal release in relation to sediment suspension in lake Taihu, China

Despite laboratory experiments that have been performed to study internal heavy metal release, our understanding of how heavy metals release in shallow eutrophic lakes remains limited for lacking in-situ evidence. This study used automatic environmental sensors and a water sampling system to conduct high-frequency in-situ observations(1-hr intervals) of water environmental variables and to collect water samples(3-hr intervals), with which to examine the release of internal heavy metals in Lake T...