近百年来龙感湖地区湖泊营养化过程

An 100-year nutrients accumulation process from lacustrine records in Longgan Lake Southeast China

由于近年来社会经济的迅速发展,湖泊富营养化问题日趋严重,其中湿地的破坏是导致入湖营养盐增加的一个重要原因。对湿地变化与湖泊营养盐状况关系的分析是制定湖泊环境整治和生态修复的重要科学依据。湖泊沉积物含有丰富的生物和理化方面的信息,在缺乏长期湖泊监测记录的情况下,可以用来重建湖泊及其流域过去变化的历史。根据龙感湖表层沉积物210Pb活度比变化,分析了该地区近百年来沉积物中湿地花粉、总磷和磁性参数,探讨了湖泊营养化过程及机理。研究表明,龙感湖近百年来营养级的增加是与湿生植被的破坏密切相关。20世纪上半叶的湖泊富营养化响应于磁性参数指示的流域土壤侵蚀速率的增加,而20世纪70年代以来湖泊营养程度的加重则与龙感湖流域农业化肥的使用和湿地植被破坏而导致湿地功能减弱有关。龙感湖流域内人类对湖周滩地的改造,破坏了湿地植被,助长了入湖物质的增加,湖泊营养相对富集,最终导致水体富营养化发生。

The Lake hutrophication is severe commonly in some areas of China as a result of rapid development of social economy in last few decades. The wetland, as the linkage between the terrestrial and aquatic environments, may perform the buffer and nutrient storage functions. The wetland vegetation, to some extent, can not only intercept the mineral transported from catchment, but also purify the water flowing into the lake. With the destruction of wetland plants, the wetland eliminates the functions of the buffers and nutrient storage. The scientific preventative measurements and restorative management require to provide more detailed background data and the relationship between wetland and lake nutrient state. Lake sediment containing large amount of ecological, physical and chemical information can be used to reconstruct the past changes of lake and its catchment. The lake eutrophication process of Longgan Lake was discussed for the last one century based on the wet plants pollen, magnetic parameter and total phosphorus analysis, combining with ^(210)Pb activity profile from a short core of central Langgan Lake, located in the boundary between Hubei and Anhui Provinces. The beginning of lake eutrophication during first half part of the 20^(th) century was related with the accelerated soil erosion in watershed deduced from pollen and magnetism, while the enhanced trophic condition since 1970 s with the wide usage of chemical fertilizer as well as the destruction of wet land vegetation, resulting in the weakened of wet land interception function. The degeneration of wetland vegetation caused the land nutrient discharges by human activities around the lake catchment. The lake nutrient enriched relatively, following by the lake eutrophication at present.