Impoundment intensity determines temporal patterns of hydrological fluctuation, carbon cycling and algal succession in a dammed lake of Southwest China.
Impoundment intensity determines temporal patterns of hydrological fluctuation, carbon cycling and algal succession in a dammed lake of Southwest China.
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DOI：
10.1016/j.watres.2018.10.032
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发表时间：
2019-01
期刊：
影响因子：
12.8
通讯作者：
Jiaoyuan Wang;Guangjie Chen;Wengang Kang;Kui Hu;Lei Wang
中科院分区：
文献类型：
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作者：
Jiaoyuan Wang;Guangjie Chen;Wengang Kang;Kui Hu;Lei Wang
世界许多地方越来越多地实施湖泊水文控制，然而，水文控制的长期生态影响及其对湖泊蓄水强度的依赖性却很少被研究。我们将表层沉积物的空间调查与沉积物岩心分析结合起来，量化了一个寡中营养湖在过去两个世纪中的湖泊学变化，该湖分别于 1957 年筑坝和 1987 年至 1990 年期间加固。将由表面沉积物粘土成分构建的水深推断模型应用于测年良好的沉积物岩心以进行水位重建。建坝后推断水深由6.2±0.9m增加到8.7±1.7m，筑坝后进一步增加到13.6±2.6m，导致水位波动幅度（WLF）增加。因此，大量沉积物的碳氮比和中值粒径分别在~1957年和~1990年飙升，反映出由于蓄水而导致的大量陆地来源输入。随着时间的推移，沿岸带和底栖硅藻持续丧失，C/N 比显着下降，碳同位素信号突然耗尽，表明 1990 年以后碳转移向远洋路径转变。虽然自1990年以来藻类产量显着增加，但自1957年以来碳和氮埋藏的积累速率呈现加速下降，反映了水储存量扩大带来的稀释效应。此外，无机碳通量与有机碳通量之间的比率以及无机碳的沉积物埋藏量均显着增加，反映出自1990年以来分层深水中水生有机碳的降解加剧和储存量较低。人们发现水文形态变量对硅藻群落产生强烈影响，随着时间的推移，与营养物和气候变量的相互作用不断增强。虽然~1960年硅藻组成发生了显着变化，但当水深提高到~10m以上或WFL幅度高于~2m时，物种丰富度和群落差异性显着下降。因此，我们的沉积物调查提供了证据，证明湖泊调节对水文形态、碳埋藏和生态变化随时间的显着影响，以及随着蓄水强度的增加，湖泊调节与其他强迫的更强相互作用。
Hydrological control of lakes has been increasingly practiced in many parts of the world, however, the long-term ecological impact of hydrological regulation and their dependence on lake impoundment intensity has been rarely examined. We combined a spatial survey of surface sediments with sediment core analyses to quantify the limnological changes over the last two centuries for an oligo-mesotrophic lake, which was dammed in 1957 and reinforced during 1987–1990, respectively. A water depth inference model constructed from surface sediment clay components was applied to a well-dated sediment core for water level reconstruction. The inferred water depth increased from 6.2 ± 0.9 m to 8.7 ± 1.7 m after dam construction and further to 13.6 ± 2.6 m after dam enforcement, resulting in an increase in the magnitude of water level fluctuation (WLF). Accordingly, bulk sediment C/N ratio and median grain size spiked in ∼1957 and ∼1990, respectively, reflecting a large input of terrestrial sources due to impoundment. With a consistent loss of littoral zone and benthic diatoms over time, a significant decrease in C/N ratio and an abrupt depletion of carbon isotopic signal suggested a shift of carbon transfer towards a pelagic pathway after ∼1990. While there was a significant increase in algal production since ∼1990, the accumulation rate of carbon and nitrogen burial displayed an accelerating drop since ∼1957, reflecting a diluting effect derived from expanding water storage. Furthermore, there was a significant increase in both the ratio between inorganic and organic carbon fluxes and sediment burial of inorganic carbon, reflecting enhanced degradation and low storage of aquatic organic carbon in stratified deep waters since ∼1990. Hydro-morphological variables were found to exert strong impact on diatom communities, with an increasing interplay with nutrient and climate variables over time. While there existed a significant shift of diatom composition in ∼1960, species richness and community dissimilarity showed a significant decrease when water depth was raised to above ∼10 m or the magnitude of WFL was above ∼2 m. Thus, our sediment surveys provide evidence on the significant impact of lake regulation on hydro-morphology, carbon burial and ecological shift over time, as well as its stronger interaction with other forcing with increased impoundment intensity.