平水期洞庭湖不同形态磷赋存特征

通过现场调查和室内实验,对平水期洞庭湖24个断面上覆水-沉积物磷的污染程度、分布特征进行研究;同时,分析了各形态磷间的相关性,探讨了磷的赋存形态对水体富营养化的影响、沉积物释放量和释放风险。结果表明,水体内总磷分布规律为南洞庭西洞庭东洞庭大通湖,东洞庭湖以颗粒态磷为主,西洞庭湖、南洞庭湖、大通湖均以溶解态磷、无机磷为主。沉积物中总磷的分布规律为南洞庭西洞庭东洞庭大通湖。东洞庭湖、西洞庭湖、南洞庭湖则以Ca-P为主,大通湖以Fe/Al-P为主。Ca-P与Fe/Al-P呈现较显著的负相关关系。大通湖释放风险较大,可释放量大;东洞庭湖有一定的可释放量,应对这两个湖泊给予较多的关注。与国内其他湖泊比较,洞庭湖沉积物中TP处于中下水平,IP在沉积物中占据较高比例。湖区沉积物中Fe/Al-P与水体中DIP、DTP、TP均具有较显著的负相关关系,存在磷的内源释放。

Occurrence Characteristics of Various Form Phosphorus in Dongting Lake during Normal-flow Period

This paper studied the distribution characteristics and pollution levels of phosphorus at the 24 sections in the DongtingLake during normal-flow period through field investigation and laboratory experiments. Besides, it analyzed the relation betweendifferent forms of phosphorus, the impacts of different forms of phosphorus on eutrophication, and releasing contents and risks ofphosphorus. The results indicate that the distribution of the total phosphorus contents during the normal-flow period ranging fromhigh to low are the Datong Lake, East Dongting Lake, West Dongting Lake and South Dongting Lake. Particulate P (PP) is thehighest content in the East Dongting Lake while dissolved P and inorganic P are the main contents in the other Lakes. Thedistribution of the total phosphorus in the sediments ranging from low to high are the Datong Lake, East Dongting Lake, WestDongting Lake and South Dongting Lake. Ca-P is the main form of P in sediments taken from the East Dongting Lake, WestDongting Lake and South Dongting Lake while Fe/Al-P in the Datong Lake. Ca-P and Fe/Al-P overwhelmingly shows negativecorrelation. The releasing contents and risks of phosphorus are high in the Datong Lake while there are some releasing contents ofphosphorus in the East Dongting Lake. Compared with other domestic lakes, the contents of TP in the sediments of the DongtingLake are not in high levels, but the contents of IP and its proportion in the TP are relatively higher. The contents of Fe/Al-P inthe sediments show negative correlation with DIP, DTP and TP respectively.