磷是滨海湿地生产力的关键限制因素之一，有机磷是磷的重要组成部分。有机磷的矿化分解是湿地溶解性无机磷（DIP）的重要补充途径，其转化速率是决定湿地营养状态和生产力的重要因素。本文以荣成天鹅湖滨海湿地为研究对象，通过采集不同季节、不同点位的表层（0～0.5 m）水样和表层沉积物样品，利用酶水解技术研究了天鹅湖水体和沉积物有机磷的生物有效性及其季节变化规律，通过相关性分析阐明了有机磷对湿地水质和富养化水平的影响；同时利用底物催化法分析了水体和沉积物磷酸酶活性及其动力学特征，揭示了湿地有机磷的周转动态和控制因素；最后分析了水体—沉积物界面磷的扩散通量，重点揭示了有机磷对湿地DIP的贡献。得出的主要结论如下：
      （1）天鹅湖水质为III～I V类水，天鹅湖已经出现轻度富营养化。有机磷是天鹅湖水体总磷重要组成部分，其中溶解性有机磷（DOP）的含量为0.039～0.123mg/L，占水体TP的29%～74%，颗粒态有机磷（POP）的含量为0.011～0.073 mg/L，占水体TP的11%～25%。通过酶水解技术研究表明，24%～31% 的DOP 和41%～82%的POP是潜在的生物可利用磷。天鹅湖溶解性磷含量具有季节差异，其中溶解性总磷（DTP）和DOP遵循春夏高而秋冬含量低的特点，溶解性无机磷（DIP）遵循秋冬高而春夏含量低的特点。有机磷空间分布具有非均一性，DOP和POP主要分布在湖心区和河口区。相关性分析表明，DOP和酶水解有机磷（EHP包括Monoester-P和Diester-P）跟水体初级生产力和水体富营养化水平具有明显的相关关系（P<0.05），它们可以作为天鹅湖水质和富营养化程度的代用指标。
      （2）天鹅湖沉积物有机磷含量为107.9～161.9 mg/kg，占沉积物总磷含量的25%～40%，其中37%～50%的有机磷是潜在的生物可利用磷。沉积物有机磷含量季节变化不明显，沉积物EHP组分空间变化较大，其中磷酸单酯磷（Monoester-P）、二酯磷（Diester-P）主要集中在河口区和湖心区，植酸磷（Phytic-P）集中在湖心区和入海口区。相关分析表明，沉积物有机磷是水体磷的重要来源，与水环境因子关系密切，在治理水体富营养化过程中，应该防止沉积物有机磷分解矿化。
      (3)天鹅湖水体碱性磷酸酶活性、磷酸二酯酶活性、植酸酶活性活性分别为0.02～0.2 mg/( L﹒h)、 0.02～0.1mg /( L﹒h)、0.2～0.3 mg /( L﹒h)。天鹅湖沉积物碱性磷酸酶活性、磷酸二酯酶分别为6.1～11.7 mg /(kg﹒h)、2.1～9.7 mg /(kg﹒h)。天鹅湖水体中Monoester-P、Diester-P和Phytic-P的周转时间分别为0.2～5.9 h、7.0～37.6 h和3.9～7.7 h。沉积物中Monoester-P和Diester-P的周转时间分别为0.1～0.2 h和0.1～0.3 h。
       (4) 天鹅湖沉积物有机磷向水体的扩散通量为1.8～3.2 mg /( m²﹒d)，年均扩散通量为2.4 mg /( m²﹒d)。有机磷对水体磷的年贡献量为21.7～99.2 t/a，平均占总磷的52%。水体DOP的酶水解的速率为0.3～1.3 mg/(L﹒d)，每天DIP的生成量是水体DIP的13.4～115.4倍，水体EHP对DIP的循环时间0.0083~0.075d，沉积物有机磷的酶水解速率为124.8～271.2 mg/(kg﹒d)，每天对沉积物无机磷的贡献为48%～96%，其沉积物EHP对沉积物无机磷的循环时间为1.0～2.1d。沉积物-水界面无机磷的扩散速率为0.0017～0.006 mg/(L﹒d)， 对水体DIP的周转时间为4.0～21.2 d，沉积物-水界面无机磷的每天扩散量占水体DIP的9%～50%；沉积物-水界面有机磷扩散速率为0.0018～0.0064 mg/(L﹒d)，对水体DOP的周转时间为19.5～98.4d。沉积物-水界面有机磷的每天扩散量占DOP的2%～10%。研究结果表明，天鹅湖水体有机磷分解速率很快，可以快速补充水体溶解态无机磷，同沉积物-水界面交换相比，成为水体溶解态无机磷主要来源。
       总之，天鹅湖水体和沉积物中能被生物所利用的EHP含量非常高。在富营养化的防治过程中，应该重视EHP对水体富营养化的贡献。在外磷负荷被控制后，内源 EHP循环供磷可能也是维持富营养化的重要过程之一。然而，内源性有机磷的释放受到磷酸酶、温度、DIP、藻类等因素的控制，在富营养化治理过程中，应该从多角度，全方位防治有机磷的分解矿化。
 

         Phosphorus（P） is one of the key limiting factors of productivity in coastal wetland, and organic phosphorus is an important component of phosphorus. The hydrolysis of organic phosphorus plays an important role in the process of eutrophication evolution and the conversion rate determines the nutrient status and productivity of the wetland. Therefore, the present study collected surface sediments and water samples (0～0.5m) in different seasons and at different locations at the Rong Cheng Swan Lake. The bioavailability and seasonal variation of organic phosphorus in lake water and sediments were studied via enzymatic hydrolysis. The correlation analysis was conducted to reveal the effects of organic phosphorus on water quality and eutrophication. Phosphatase activity and enzymekinetic characteristics were analyzed to reveal the controlling factors of organic phosphorus turnover. Finally, the fluxes of phosphorus between water sediment interface were calculated, and the contribution of organic phosphorus to the soluble inorganic phosphorus was discussed. The main findings and conclusions are shown as follows:
        (1) The water quality was III - IV and water has been a slight eutrophication in Swan Lake. Organic phosphorus was an important component of TP in Swan Lake. The content of DOP was 0.039～0.123 mg/L, accounting for 29%～74% of total phosphorus. POP content was 0.011～0.073 mg/L, accounting for 11%～25 % of total phosphorus. The enzymatic hydrolysis of organic phosphorus showed that 24%～31% of DOP and 41%～82 % of POP were potential available phosphorus. The content of dissolved phosphorus varied with seasons: among which DTP and DOP are characterized by higher content of spring/summer than that of autumn/winter, whereas DIP followed distinct seasonal variation with higher conent in autumn/winter than that of spring/summer. The organic phosphorus was concentrated in center lake and river estuary area with heterogeneity. The correlation analysis suggested that DOP and enzyme hydrolysis phosphorus (EHP) such as Monoester-P and Diester-P could be used as an indicator of primary productivity and eutrophication.
      （2）The organic phosphorus content in the sediments of Swan Lake was 107.9～161.9 mg/kg, accounting for 25%～40% of total phosphorus, and 37%～50% of organic phosphorus was potential available. The sediment organic phosphorus did not varied greatly with seasons. The sediment EHP significantly changed in lake area. The monoester phosphorus (Monoester-P) and diester phosphorus (Diester-P) were concentrated in the river estuary and center lake, while phytate phosphorus (Phytic-P) was distributed mainly in center lake and sea estuary. Correlation analysis showed that sediment organic phosphorus, the important source of phosphorus in water,was closely related to water quality. In view of eutrophication, the release and hydrolysis of organic phosphorus need further investigation.
       （3）The activity of alkaline phosphatase , phosphodiesterase and phytase in Swan Lake, respectively,were 0.02~0.2 mg/( L﹒h),0.02~0.1mg /( L﹒h) and 0.2~0.3 mg /( L﹒h). The activity of alkaline phosphatase and phosphodiesterase in the sediments of Swan Lake ,respectively,was 6.1～11.7 mg /(kg﹒h) and 2.1～9.7 mg /(kg﹒h). The turnover time of Monoester-P, Diester-P and Phytic-P in the water of Swan lake,respectively, were 0.2～5.9 h、7.0～37.6 and 3.9～7.7 h. The turnover time of Monoester-P and Monoester-P in the sediments were0.1～0.2 h and 0.1～0.3 h, respectively.
       (4）The flux of organic phosphorus between sediment-water interface was 1.8～3.2 mg /( m2﹒d) with average 2.4 mg /( m2﹒d). The annual flux of organic phosphorus was 21.7～99.2 t/a, which accounted for 52% of total phosphorus flux. The enzymatic hydrolysis rate of DOP was 0.3～1.3mg/(L﹒d) in surface water in Swan Lake. The amount of DIP per day is 13.4 ～115.4 times of water DIP, and the DOP cycle time ranged 0.008~0.08 d. In comparison, the sediment organic phosphorus hydrolysis rate was 5.2～11.3 mg/(kg﹒h) and represented 48% ~96% of sediment inorganic phosphorus，and the cycle time ranged 1.0~2.1d. The inorganic phosphorus flux between the sediment-water interface was calculated as 0.0017～0.006 mg/(L﹒d) and accounted for 9%～50% of sediment inorganic phosphorus. The diffusion time for inorganic phosphorus was 4.0～21.2 d. The flux of organic  phosphorus between sediment-water interface ranged 0.0018～0.0064 mg/(L﹒d), and the diffusion time for DOP was19.5～98.4d. The daily flux of organic phosphorus between sediment-water interface accounted for 2%～10% of water DOP. The results show that the decomposition rate of organic phosphorus in lake water was very fast, and it can quickly supplement the dissolved inorganic phosphorus in water. Compared with the sediment water interface exchange, organic phosphorus becomes the main source of dissolved inorganic phosphorus in water.
       In conclusions, the content of potential available organic phosphorus in the water and sediments of Swan Lake is very high. For eutrophication remediation, organic phosphorus deserved further investigation. When external phosphorus load was reduced, the internal phosphorus cycling via organic phosphorus hydrolysis represented an important source of water phosphorus. However, the release of endogenous organic phosphorus is controlled by factors such as phosphatase, temperature, DIP and algae, etc. Therefore, in the process of eutrophication management, it is necessary to prevent and control the release of endogenous phosphorus from various angles.