九龙江口水体碱性磷酸酶活性及其对磷循环的影响

Alkaline Phosphatase Activity and Its Role in Phosphorus Cycle in the Jiulong River Estuary

为揭示富含磷酸盐(PO_(4)^(3-))的河口碱性磷酸酶(alkaline phosphatase,AP)与磷循环的关系,测定了九龙江口水体中溶解态碱性磷酸酶活性(dissolved alkaline phosphatase activity,DAPA)、颗粒态碱性磷酸酶活性(particulate alkaline phosphatase activity,PAPA)和总碱性磷酸酶活性(total alkaline phosphatase activity,TAPA),分析了各碱性磷酸酶活性的时空分布特征及其与环境因子、磷营养水平的相关性。结果表明,九龙江口TAPA空间差异显著,河口上游显著高于河口下游,表层略高于底层;TAPA季节变化较为明显,秋季TAPA介于85.5~876.5 nmol/(L·h),冬季介于7.5~639.8 nmol/(L·h);秋季AP主要以颗粒态存在,PAPA对TAPA的平均贡献率为(84.9±9.5)%,而冬季PAPA和DAPA对TAPA的贡献率分别为(54.1±26.4)%和(45.9±26.4)%,差别不大。统计分析表明,DAPA与溶解态有机磷(dissolved organic phosphorus,DOP)浓度呈现极显著的正相关,与盐度呈现极显著的负相关,说明溶解态AP主要由DOP诱导而产生,并受河-海水混合影响;PAPA与悬浮颗粒物(suspended particulate matter,SPM)浓度呈现极显著正相关,与叶绿素a(Chl-a)相关不显著,说明附着在颗粒物上的细菌可能是颗粒态AP的主要来源。上述结果说明,有机磷的微生物矿化作用可能是富磷河口溶解态无机磷(dissolved inorganic phosphorus,DIP)的重要来源。

In order to reveal the role of alkaline phosphatase in the PO_(4)^(3-) rich estuaries,the activities of dissolved alkaline phosphatase activity(DAPA),particulate alkaline phosphatase activity(PAPA)and total alkaline phosphatase activity(TAPA)in the Jiulong River Estuary were measured.The spatial and temporal distribution of alkaline phosphatase activity and its correlation with environmental factors and phosphorus nutrition level were studied.The results showed that the TAPA in the upstream of the estuary was significantly higher than that in the downstream,and it was slightly higher in the surface layer than in the bottom layer.The range of TAPA in autumn was 85.5-876.5 nmol/(L·h),which was higher than that in winter 7.5-639.8 nmol/(L·h).In autumn,alkaline phosphatase mainly existed in particulate,and the average contribution of PAPA to TAPA was(84.9±9.5)%.In winter,the contributions of PAPA and DAPA to TAPA were(54.1±26.4)%and(45.9±26.4)%,respectively.Statistical analysis showed that DAPA was significantly positively correlated with dissolved organic phosphorus(DOP)and negatively correlated with salinity.Therefore,it could be speculated that dissolved AP was mainly induced by DOP and controlled by the mixing of river and sea water.PAPA was highly positively correlated with total suspended particulate matter(SPM),indicating that particle-attached bacteria might be the main sources of particulate AP.These results suggested that the microbial mineralization of organic phosphorus in the Jiulong River Estuary may be an important source of dissolved inorganic phosphorus(DIP)besides physicochemical processes.