Distribution of colloidal enzymatically hydrolysable phosphorus in natural waters

Abstract

分别在太湖草型湖区胥口湾及藻型湖区梅梁湾采集水样,采用常规过滤与切向流超滤相结合的方法,将水体中的颗粒/胶体依据粒径大小分离,通过测定计算得到64-1μm,1-0.5μm,0.5-0.1μm,0.1μm-1nm,<1nm五个粒级的可酶解磷含量.同时采集太湖引江济太工程长江调水口—望虞河口水样、千岛湖水样及千岛湖下游河流型水库富春江段水样进行分析.结果显示,5种典型水体中颗粒相的可酶解磷含量占总可酶解磷含量的比重较高,胶体相的可酶解磷也占了相当的比重,是生物必需磷不可忽视的重要储库.望虞河口河水总磷0.216mg/L,可酶解磷含量达0.174mg/L,其输入可能对太湖水体生物有效磷浓度的增加起到重要的贡献,引江济太调水时具有一定生态风险.对于胶体范围的可酶解磷,胥口湾、望虞河的胶体态可酶解磷主要分布在较大、中胶体范围,梅梁湾和千岛湖的胶体态可酶解磷主要分布在中、微胶体范围,富春江水库的胶体态可酶解磷分布的相对比较均匀.;Contents of enzymatically hydrolysable phosphorus (EHP) in particle and colloidal phases in Lake Taihu were analyzed. Colloid in lake water was separated by tangential flow ultrafiltration, which included the component with diameters from 1nm to 1000nm. The EHPs from Wangyu River, a large water channel connected Lake Taihu with Yangtze River, and from Lake Qiandao and Fuchun River were also studied. Mean of particle EHP (particle size larger than 1000nm) accounted 58% of total EHP, which was the main contributor in the water. Mean of colloidal EHP accounted 35% of total, which also shows a high ratio compared to the true dissolved phosphorus. During the investigation period, total phosphorus and EHP in Wangyu River were 0.216mg/L and 0.174mg/L, respectively, suggesting that there is a high ecological risk to pump too much Yangtze River water to Lake Taihu. In Lake Taihu, percentage of micro-size colloid in marcophyte dominated zone (Xukou Bay) was much higher than that in cyanobacteria dominated zone (Meiliang Bay).