Effects of dam construction and increasing pollutants on the ecohydrological evolution of a shallow freshwater lake in the Yangtze floodplain.
Effects of dam construction and increasing pollutants on the ecohydrological evolution of a shallow freshwater lake in the Yangtze floodplain.
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DOI：
10.1016/j.scitotenv.2017.11.181
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发表时间：
2018-04
期刊：
影响因子：
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通讯作者：
Linghan Zeng-;S. McGowan;Yanmin Cao;Xu Chen
中科院分区：
文献类型：
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作者：
Linghan Zeng-;S. McGowan;Yanmin Cao;Xu Chen
提供各种社会、经济和生物效益的大型河流-洪泛平原系统正遭受广泛而强烈的人为干扰。然而，人们对洪泛区湖泊对多种压力源的反应知之甚少。长江及其河漫滩是中国的一个重要地区，为3亿多人口提供了水和粮食资源。水文调控和社会经济发展给这一生态要地带来了深刻的负面影响。为了更好地理解河漫滩湖泊对多种压力的年代际响应，对阜头湖铅-210测年岩心进行了沉积物粒度、地球化学元素、硅藻和手摇虫等指标的分析。分析表明，1935年和20世纪70年代初修建的大坝稳定了富头湖的水文条件，阻碍了富头湖与长江的相互作用，导致富头湖主要元素（Mg、Al、Fe）输入湖中减少，与大型植物相关的水栖类（C. sylvestris-type，P. C. s .）增加。penicillatus-type andParatanytarsussp)。20世纪90年代末以后，主要元素进一步减少，中位粒度增大，主要原因是长江河床的侵蚀和三峡大坝蓄水导致长江上游富主要元素沉积物供给量减少。栖藻和硅藻的组合表明，大坝建设引起的水文稳定刺激了大型植物的生长，这可能对缓冲生态系统状态向浮游植物为主和浑浊状态的转变以及持续的富营养化起到重要作用。然而，最近锌、总磷的增加以及富营养化硅藻和摇尾藻物种的出现表明水质恶化的初步迹象，这可能与水文稳定和水产养殖的共同作用有关。总体而言，抚头湖沉积物记录强调了水文变化和污染物负荷之间的相互作用在确定河漫滩湖泊生态系统状态中的重要性。
Large river-floodplain systems which provide a variety of societal, economic and biological benefits are undergoing extensive and intensive human disturbance. However, floodplain lakes responses to multiple stressors are poorly understood. The Yangtze River and its floodplain which provide water and food resources for more than 300 million people are an important region in China. Hydrological regulation as well as socio-economic development have brought profound negative influence on this ecologically important area. To improve understanding of decadal-scale responses of floodplain lakes to multiple stressors, lake sediment proxies including particle size, geochemical elements, diatoms and chironomids were analysed in a lead-210 dated core from Futou Lake. The analyses show that dams constructed in 1935 and the early 1970s stabilized hydrological conditions in Futou Lake and impeded the interaction with the Yangtze River, resulting in a decrease in major elements (e.g., Mg, Al, Fe) transported into the lake and an increase of macrophyte-related chironomids (C. sylvestris-type,P. penicillatus-type andParatanytarsussp.). After the late 1990s, further decreases in major elements and increases in median grain size are attributed to the erosion of the Yangtze riverbed and declining supply of major elements-enriched sediments from the upper Yangtze caused by the impoundment of the Three Gorges Dam. Chironomid and diatom assemblages indicate that hydrological stabilization caused by dam constructions stimulated the growth of macrophytes, which may be important in buffering against an ecosystem state change towards a phytoplankton-dominated and turbid state with ongoing eutrophication. However, a recent increase in Zn, TP and the emergence of eutrophic diatom and chironomid species indicate initial signs of water quality deterioration which may be related to the combined effects of hydrological stabilization and aquaculture. Over all, the sediment record from Futou Lake emphasizes the importance of interactions between hydrological change and pollutant loads in determining floodplain lake ecosystem state.