红枫湖沉积物内源磷释放通量估算方法的对比研究

湖泊沉积物内源磷是湖泊水体磷的重要来源,但目前对内源磷释放通量的科学估算缺乏定量研究。本文以贵州红枫湖为研究对象,对比研究了野外调查分析法、模拟实验法和扩散模型法等3种估算方法下的红枫湖沉积物内源磷释放通量。结果表明,野外调查分析法可宏观获取水体污染物来源的概况,但对采样点布设、采样频次和周期等要求较高,估算结果往往存在较大偏差和不确定性;模拟实验法可粗略获得沉积物磷释放通量,但由于取样和实验培养过程破坏了沉积物的物理化学结构,估算结果难以精确;扩散模型法可定量估算沉积物磷释放通量,但须与沉积物-水界面高分辨率观测数据相结合才能使结果可靠。红枫湖沉积物内源磷输入对水体磷污染的贡献较高(25.7%~46%),因此在富营养化治理过程中,一方面应继续强化外源污染治理,另一方面亟待加强对沉积物内源磷释放的有效控制。

Comparative Study on Quantitative Estimations of Phosphorus Release Flux from Sediments of Lake Hongfeng, Guizhou Province, China

Phosphorus(P)released from sediments is considered to be an important source of P in lake waters, but currently quantitative researches on fluxes of internal-P loading are still lacking. In this study, comparative studies on the methods of flux estimation of internal P release, e.g. field survey analysis, simulating experiment and the diffusion model were investigated to accurately estimate the contribution of the internal P flux in Lake Hongfeng. Rough contributions of different pollutant sources could be obtained by field survey in macro scale, but the results often have big error and uncertainty, as the harsh requirements of the working method are hard to be met practically. Since the physical and chemical structure of the sediments is destroyed during the sampling and cultural experiment, it is difficult to estimate accurately by the simulating experiment method. The diffusion model method has advantages in quantitative flux estimations. It is worth noting that high-resolution data of P at the sediment-water interface is crucial for reliable and quantitative calculation based on the diffusion model method. Our estimation results show that the flux of internal P release in Lake Hongfeng is reasonably high, accounting for 22%~46% of the total P in overlying waters. Therefore, in order to prevent the lake eutrophication fundamentally, it is necessary to 1) strengthen the external pollution governance, and 2) reduce the release of internal P earnestly.