| 摘要: |
| 长江中下游地区是我国淡水湖泊比较集中的地区.该地区绝大多数湖泊为浅水湖泊.所有的城郊湖泊都已经富营养化,其他湖泊的营养状况均为中营养-富营养,处于富营养化的发展中.这些湖泊富营养化的原因同流域上的人类活动有很大的关系.一方面,工业、农业和城市生活污水正源源不断地向湖泊中排放,另一方面,人类通过湖泊围垦、湖岸忖砌、水产养殖等破坏自然生态环境,减少营养盐输出途径.国际上对于浅水湖泊富营养化治理的经验表明,即使流域上的外源污染排放降到历史最低点,湖泊富营养化问题依然突出.其原因与浅水湖泊底泥所造成的内源污染有关.动力作用导致底泥悬浮,影响底泥中营养盐的释放,也影响水下光照和初级生产力.控制浅水湖泊富营养化,除了进行外源性营养盐控制之外,还必须进行湖内内源营养盐的治理.治理内源营养盐的有效途径是恢复水生植被,控制底泥动力悬浮与营养盐释放.而要进行水生植被恢复,必须进行湖泊生态系统退化机制及生态修复的实验研究. |
| 关键词: 长江中下游地区 浅水湖泊 富营养化 机制 控制 |
| DOI：10.18307/2002.0301 |
| 分类号: |
| 基金项目:中国科学院知识创新项目"太湖水环境预警"(KZCX2-311);中国科学院战略重大项目"长江中下游地区湖泊富营养化发生机制与控制对策";国家自然科学基金(40071019) |
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| Approaches to Mechanisms and Control of Eutrophication of Shallow Lakes in the Middle and Lower Reaches of the Yangze River |
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QIN Boqiang
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Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, P. R. China
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| Abstract: |
| The middle and lower reaches of the Yangtze River are one of the central areas of freshwater shallow lakes in China. Most of the lakes have been under mesotrophic or eutrophic conditions the latter are especially common in urban lakes. Human activities have played a key role in the eutrophication process from at least two aspects: continuous effluents of industrial, agricultural and domestic wastewater could add nutrient to the lake; and reclamation stone-built dikes cultivation could damage natural habitats and reduce nutrient output from the lake. The seriousness of eutrophication has aroused attention of national government. Two of the "Three Lakes" Water Pollution and Prevention Control Program that give priority to the Tenth-Five-Year-Plan of China are situated in the plain i. e.,Taihu Lake and Chaohu Lake. The nutrient status has been under a relative high level in most lakes. The eco-environmental questions in lakes are conspicuous even though local governments have taken some measures to prevent further environmental deteriorations. Steps dealing with external nutrient loadings have achieved good results in deep lakes internationally while they are no longer so effective in shallow lakes because we lack a through understanding of mechanisms of eutrophication in shallow lakes. World-acknowledged experiences of shallow lakes eutrophication control have proved that eutrophication still prevails even though area-source nutrient loading to the lake could be reduced to a minimum level,Internal sources from the sediment may certainly relate to the maintenance of eutrophication, The kinetics of water could re-suspend sediments and effect the nutrient release process underwater light intensity and primary production as well To control eutrophication in shallow lakes must take both external loading of nutrient and internal loading into consideration. One of the effective measures for internal loading is the restoration of aquatic plants in order to inhibit the re-suspension and sediment release. Researches on the experimental ecological restoration and functions of ecosystem deterioration are needed. As a result,external control on nutrient source pollution is not enough in shallow lakes; internal nutrient within lakes must be emphasized. Two techniques have been applied in internal loading control i.e.,dredging and macrophytes restoration. The former requires a complete knowledge on the trophic history in lake ecosystem so that an exact schedule on the scope and depth of dredging could be determined lest newlyexposed sediments become fresh internal release source. The latter could inhibit sediment suspension under dynamic conditions and absorb nutrient within lakes so as to diminish nutrient load as well. Macrophytes flourishing and algae bloom outbreak are two aspects of eutrophication in lakes. Why macrophytes-dominated lake could be evolved into an algae-dominate one? How to revolve the process? Future macrophytes restoration must answer them. Researches abroad prove that a macrophytes-dominated lake could be turned into an algae-dominated one under strong external disturbances and steady high lake level; once algae-dominated,the lake would come to another steady state for nutrient cycling To restore macrophytes and get cleaner water,this cyclic process must be broken down. Consequently,it is strongly recommended that researches on the mechanisms and control of eutrophication in shallow lakes be initiated,so that a theoretical and technical basis could be provided for future launching national programs on eutrophication control in China. |
| Key words: Middle and lower reaches of the Yang tze River shallow lakes lake eutrophication control mechanism |
