College of Earth Sciences and Engineering, Hohai University, Nanjing, 211100, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, China.
Environ Sci Pollut Res Int. 2020 May;27(15):17923-17934. doi: 10.1007/s11356-020-08348-5. Epub 2020 Mar 12.
Eutrophication and algal blooms have recently been found in the backwater areas of some tributaries in the Three Gorges Reservoir (TGR), for which phosphorus (P) is an important driving factor. However, P species in the TGR sediments at different water levels were little known. In this study, five P species of the TGR sediments during the high and low water level periods were analyzed with a sequential extraction method. The total P (TP) concentrations were 714.88 ± 37.86 μg/g and 697.57 ± 111.49 μg/g at the low and high water levels, respectively. The concentrations of P species decreased in the orders detrital P > authigenic P > organic P > iron-bound P > exchangeable P at the low water level and detrital P > organic P > authigenic P > iron-bound P > exchangeable P at the high water level. P in the TGR sediment sourced mainly from the upstream input at the low water level but from the inputs of tributaries and hillslope soils at the high water level. The bioavailable P (BAP) possessed > 29.5% of total P in the two periods. The total storages of total P and BAP were estimated to be about 1.34 × 10 t and 1.77 × 10 t, respectively during 2003-2017. It was further found that the BAP concentration significantly increased from periods I (2003-2009), II (2010-2014), to III (2015-2017), while the deposition flux and storage of BAP were the highest in period II. Our findings provide new insight into the P cycle and benefit eutrophication treatment in the TGR.
三峡水库（TGR）一些支流的回水区域最近出现了富营养化和藻类水华现象，而磷（P）是一个重要的驱动因素。然而，TGR 不同水位沉积物中的 P 形态知之甚少。本研究采用连续提取法分析了 TGR 高、低水位期的 5 种 P 形态。TGR 沉积物在低水位期和高水位期的总磷（TP）浓度分别为 714.88±37.86μg/g 和 697.57±111.49μg/g。在低水位期，各形态 P 浓度顺序为碎屑磷＞自生磷＞有机磷＞铁结合磷＞可交换磷，而在高水位期，各形态 P 浓度顺序为碎屑磷＞有机磷＞自生磷＞铁结合磷＞可交换磷。TGR 沉积物中的 P 主要来源于低水位期的上游输入，而高水位期则来源于支流和山坡土壤的输入。高、低水位期的生物有效磷（BAP）分别占总磷的>29.5%。2003-2017 年期间，TGR 沉积物总磷和 BAP 的总储量估计分别约为 1.34×10^5t 和 1.77×10^5t。进一步发现，BAP 浓度从时期 I（2003-2009 年）、II（2010-2014 年）到 III（2015-2017 年）显著增加，而 BAP 的沉积通量和储量在时期 II 最高。本研究结果为 TGR 地区的磷循环和富营养化处理提供了新的认识。
