Lake rehabilitation: A status report

The widespread recognition of lake degradation as a major environmental concern has led to accelerated efforts to better protect and manage lake resources. Where it is too late for avoidance strategies, lake rehabilitation is receiving increasing attention as a natural resources management option. In recent years, a significant number of lake rehabilitation experiences has been documented throughout the world, and many nations and states have embarked upon major lake rehabilitation programsLake rehabilitation is not a ready-to-go technology at this time and still must be regarded as partly experimental. Nevertheless, there have been a number of notably successful lake rehabilitation experiences. Reducing or halting the influx of undesirable materials is the sine qua non for lake rehabilitation. In most successful experiences to date, this has been accomplished by diversion and/or wastewater treatment. A number of in-lake strategies have also been employed to rehabilitate degraded lakes, often as part of an overall restoration plan. Techniques that appear to be most useful include dredging and nutrient inactivation. Several examples of successful applications are noted.Although efforts to rehabilitate lakes have produced a mixed record, there are encouraging results that suggest the viability of this approach. Lake rehabilitation, however, is no substitute for environmental management strategies that provide for protection of lake ecosystems in the first place.     

Patternising phytoplankton dynamics of two shallow lakes in response to restoration measures by applying non-supervised artificial neural networks

Long-term time-series data sets of two shallow Dutch lakes, Lake Veluwemeer and Lake Wolderwijd were subjected to ordination and clustering by means of non-supervised artificial neural networks (ANN). Splitting of the data sets into sub-series corresponding with three different management periods have allowed a comparative analysis of both the short-term seasonal and long-term phytoplankton dynamics in relation to the restoration measures. The lakes were considered as hyper-eutrophic and have been managed both with bottom-up and top-down management approaches. Results of the study have demonstrated that non-supervised ANN allow to elucidate causal relationships of complex ecological processes (1) within the specific genus, Oscillatoria and Scenedesmus and (2) the combination of external nutrient control and in-lake food web manipulation of the two lakes achieved to control eutrophication.     

Watersheds Nutrient Loss and Eutrophication of the Marine Recipients: A Case Study of the Jiaozhou Bay,China

Industrialization and urbanization along the coastal population centers have brought great changes in the land cover and material fluxes from watersheds to receiving bays and estuaries. We have embarked a multiyear research project on “Watersheds Nutrient Loss and Eutrophication of Jiaozhou Bay” for the period of 2000 to 2004, funded by the Natural Science Foundation of China to examine human influence on the marine sector of ecosystem. Jiaozhou Bay, located in the southern part of Shandong Peninsula, was selected because of the existence of long-term hydrographic and meteorological records since the 1930s and recent observations on the marine ecological variables. We have made extensive and periodic measurements on the water movement, nutrients, phytoplankton, and microbe in water column and bottom sediments. Box and 3-dimensional hydrodynamic models were developed and utilized to understand the evolution of eutrophic status with time. It was found that primary productivity has suffered from silica depletion followed by phosphate, and the dominance of large phytoplankton has been replaced by small-size communities. These ecosystem changes were brought by the changes in the relative contribution among major pathways and concentrations, owing to the human activities in the watershed. Eight articles in this volume reported various aspects of the linkage between watershed human activities and ecosystem for the Jiaozhou Bay as the initial outcome of this project.     

南宁市南湖富营养化防治对策及综合整治方案的研究

由于大量生活污水未经处理排放南宁市南湖,南湖富营养化状已非常严重,各种水体功能均受到严重影响,治理南湖已刻不容缓。     

生态水力学原理在巢湖富营养化控制中的应用

首先介绍了生态水力学原理,接着在分析研究工作的基础上,对巢湖水质富营养化问题进行了分析和探讨,期望从理论与实践的结合上,对巢湖富营养化治理起到一定的科学指导作用。     

我国湖泊的限磷,禁磷现状及对策

介绍了含磷洗涤剂对湖泊富营养化的影响；国内外限磷、禁磷研究的发展趋势以及我国水污染治理中对含磷洗涤剂应采取的具体对策。并结合我国国情，提出了应地制宜地制定限磷、禁磷政策的建议。     

深圳市污染物排放总量与近岸水体营养盐变化的统计分析(IV)

从统计学角度分析深圳市污染物净排放总量与其近岸东、西部水体富营养化之间关系。研究结果表明:深圳市东部海域水体活性磷酸盐、EI值以及西部海域水体中的N:P分别与近岸排污呈现较好的相关性,他们似可作为深圳排污与近岸水体富营养化关系指标。深圳东西部水体由于地理条件、海湾的封闭性的差异,造成东部水体更易受到深圳近岸排污的影响,而西部水体较为开放,受珠江水系、深圳和香港排污等多重因素的影响,因此在研究深圳近岸污染物排放总量与赤潮发生关系时,应选择东部水体作为研究对象。     

水体富营养化及其治理措施

由于大量未经处理的污水直接进入水体，使得水体中氮磷营养物质不断积累，部分藻类及水生生物过度繁殖，最终导致了水体的富营养化，为治理富营养化水体可以采取截污、清淤挖泥、引水冲污等工程性措施，也可以采取利用生物生长需吸收氮磷营养物质这一自然过程来达到去除氮磷的目的，即生物性措施。     

三种水生植物在不同季节去污能力的对比研究

在实验室人工模拟太湖地区春季和冬季不同气候条件下,对三种抗寒去污性能较强的水生植物伊乐藻、石菖蒲和水芹菜在不同营养状态下和不同季节温度条件下去除氮磷的效果进行了系统地对比研究。结果表明:这三种植物均能较好地吸收水中的营养物质,其中以水芹菜脱氮除磷效果最好;总体上植物在春季吸收氮的效果要好于冬季,但对磷的季节吸收差异没有氮明显。可利用沉水植物和挺水植物对氮磷去除的各自优势分别筛选吸收效果较好的植物品种,构成双层次群落结构(FAMS)用以修复太湖地区富营养化水体。     

东牙溪水库水环境质量评价及保护措施

采用一种新的模糊评价法对东牙溪水库水质进行了富营养化评价，并针对污染现状提出了相应的保护措施。