三峡库区支流的河-湖两态及其对沉积物不同形态磷含量的影响

三峡大坝独特的调度运行方式决定了三峡库区支流在水动力方面显著区别于自然河流.为探究库区特殊调水机制下支流沉积物内源磷的动态变化，于2016年在库区北岸最大支流澎溪河中游的高阳平湖段进行了8次（1、 3～8和10月，每月一次）水体和沉积物样品采集，分析其不同形态磷含量，并对流速、水深和沉积物碱性磷酸酶活性等进行了一系列分析.结果表明，高阳平湖段水体类型可分为5、 6月前的深水湖泊及5、 6月后至三峡大坝秋季再次蓄水间的典型河流两种水文状态；湖泊状态下上覆水中可溶性磷浓度比河流状态高42.48%,利于沉积物表层沉积物中弱结合态磷（NH₄Cl-P）处于吸附-释放的平衡状态；春季水华初期，随着上覆水温度的升高和沉积物中碱性磷酸酶活性的提高，沉积物中潜在可移动磷含量升高，而稳定形态磷含量降低，表现出向潜在可移动磷形态转变的趋势，这可能是春季水华可利用的磷源之一；高阳平湖沉积物中稳定形态磷含量约占总磷含量的81.79%,变异系数相对较小（2.90%～4.21%）,并且存在显著随时间累积趋势（P<0.05）.揭示了沉积物不同磷形态转化及其与水体存在类型的关系，为三峡库区其...

River-Lake States in the Tributary of the Three Gorges Reservoir Area and Their Effects on the Phosphorus Content of Different Forms in the Sediment

The unique operation mode of the Three Gorges Dam has determined that the tributaries of the Three Gorges Reservoir (TGR) are significantly different from natural rivers in terms of hydrodynamics. The aim of this study was to explore the dynamic changes of internal phosphorus in tributary sediments under special water transfer mechanisms in the reservoir area. In 2016, we conducted samplings eight times (January, March-August, and October, once a month) in the Gaoyang Lake, which is located in the middle section of the Pengxi River, the largest tributary in the northern bank of the TGR. Samples of the adjacent overlying (AOL) water and sediment were collected, and a series of analyses were carried out on the flow velocity, water depth, and alkaline phosphatase activity (APA) of sediments. The results indicated that the waterbody types of the Gaoyang Lake can be divided into two hydrological states:deep lakes before May and June and typical rivers from May and June until the Three Gorges Dam re-flooding in autumn. The concentration of dissolved phosphorus in the AOL water during the lake state was 42.48% higher than that in the river state, which was beneficial for the weakly bounded phosphorus (NH₄Cl-P) in the sediment surface to be in an adsorption-releasing equilibrium state. At the beginning of the spring algal bloom, with the increase in water temperature and APA in the sediments, the content of potential mobile phosphorus (PMP) in the sediments increased; however, the stable-form phosphorus content decreased, showing a tendency of transformation between these two forms of phosphorus, which may be one of the available phosphorus sources for algal blooms. The stable-form phosphorus content in the sediments of the Gaoyang Lake accounted for approximately 81.79% of the total phosphorus content, its coefficient of variation was relatively small (2.90%-4.21%), and there was a significant trend of accumulation over time (P<0.05). The study revealed the transformation of different phosphorus forms in sediments and their relationship with the state shift of the waterbodies, and provided a reference to understand the internal phosphorus cycle in other tributaries of the TGR area or other reservoir tributaries under similar situations.