Luo Yu-Hong, Nie Xiao-Qian, Li Xiao-Ling, Dai Ze-Long, Xu Tao, Huang Ying-Ping
College of Hydraulic & Environmental Engineering, Three Gorges University, Yichang 443002, China.
Innovation Center for Geo-Hazards and Eco-Environment in Three Gorges Area, Yichang 443002, China.
Huan Jing Ke Xue. 2017 Jun 8;38(6):2345-2354. doi: 10.13227/j.hjkx.201610114.
The distribution and vertical variation of phosphorus forms in sediments along Xiangxi River were analyzed with Hedley classification method, meanwhile the influences of physical and chemical properties of overlying and interstitial water on the release of phosphorus in sediment were discussed. The major findings showed that the pH values in the overlying and interstitial water increased from 4.72 to 8.55, and were slightly acidic in summer, while weak alkaline in other seasons. The redox potential of sediment was in the reduction state overall. The annual variation range of total phosphorus (TP) content in the overlying and interstitial water, and that in the sediment was 0.02-0.48 mg·L and 0.48-1.45 g·kg, respectively. The distribution features of TP content in the sediment were the same with those in the interstitial water along the Xiangxi River. It was interesting that the content of TP in the interstitial water in spring and summer was higher than that in autumn and winter, but that in the sediment of Xiangxi River was opposite. The content of different phosphorus (P) forms decreased successively:HCl-P (HCl extracted phosphorus)> Res-P (residual phosphorus)> NaOH-P (NaOH extracted phosphorus)> NaHCO-P (NaHCO extracted phosphorus)> HO-P (water-soluable phosphorus). The reductive environment of the interface between sediment and overlying water, and pH of water in spring (weak alkaline) and summer (slightly acidic), were conducive to phosphorus release from sediment into overlying water, increasing the eutrophication risk. TP content in the interstitial water was closely related to that in sediment. The PO-P in 4 sampling areas diffused from the interstitial water into the overlying water with diffusive fluxes in the range of 0.01-0.04 mg·(m·d). All of these findings indicated that sediments is an important source of nutrient for the overlying water.
采用Hedley分级法分析了香溪河沉积物中磷形态的分布及垂向变化，同时探讨了上覆水和间隙水的理化性质对沉积物中磷释放的影响。主要研究结果表明，上覆水和间隙水的pH值从4.72升高到8.55，夏季呈弱酸性，其他季节呈弱碱性。沉积物的氧化还原电位总体处于还原状态。上覆水、间隙水和沉积物中总磷（TP）含量的年变化范围分别为0.020.48 mg·L和0.481.45 g·kg。香溪河沉积物中TP含量的分布特征与间隙水相同。有趣的是，春夏季间隙水中TP含量高于秋冬季，但香溪河沉积物中TP含量则相反。不同磷形态的含量依次降低：HCl-P（HCl提取磷）>Res-P（残留磷）>NaOH-P（NaOH提取磷）>NaHCO-P（NaHCO提取磷）>HO-P（水溶性磷）。沉积物与上覆水界面的还原环境以及春季（弱碱性）和夏季（弱酸性）的水体pH值有利于沉积物中磷向上覆水释放，增加了富营养化风险。间隙水中TP含量与沉积物中TP含量密切相关。4个采样区域的PO-P从间隙水扩散到上覆水，扩散通量范围为0.01~0.04 mg·(m·d)。所有这些结果表明，沉积物是上覆水营养物质的重要来源。
