典型岩溶流域不同湿地水体氮磷分布及富营养化风险评价

Nitrogen and phosphorus distribution and eutrophication risk assessment of different wetland waters in typical karst watershed

【目的】探索岩溶流域不同湿地水体中氮、磷的分布特征及富营养化风险,为岩溶地区的湿地和水资源保护提供理论依据及技术参考。【方法】以滇东南典型岩溶流域普者黑为研究区,通过对流域内沼泽湿地、库塘湿地、河流湿地、湖泊湿地的枯水期、平水期和丰水期水质进行监测,测定不同湿地水体中氮(总氮(TN)和氨氮(NH3-N))、磷(总磷(TP)和正磷(PO4^3-P))和溶解氧(DO)质量浓度的变化,并利用对数型幂函数普适指数对水体富营养化风险进行了评价。【结果】普者黑岩溶流域不同湿地水体中氮、磷质量浓度的时空分布特征明显,在丰水期最高,达到Ⅳ类水质标准,枯水期最低。湿地水体中,TN、NH3-N和TP、PO4^3-P最高质量浓度均出现在丰水期的河流湿地中,分别达到1.72,0.95和0.113,0.035 mg/L,DO质量浓度在平水期的库塘湿地最高,达7.97 mg/L;枯水期湖泊湿地水体中TN、NH3-N和TP、PO4^3-P质量浓度最低,分别为0.18,0.13和0.016,0.006 mg/L,在丰水期的沼泽湿地DO质量浓度最低,为4.39 mg/L。在不同类型的湿地中,氮、磷质量浓度由高到低表现为河流湿地>库塘湿地>沼泽湿地>湖泊湿地,湿地大部分水体在不同时期均处于中等营养化状态,属磷限制状态。【结论】普者黑岩溶流域4种湿地水体在丰水期的富营养化程度为中等等级,面临水质恶化的风险,因此需合理利用及保护现有湿地,保证岩溶水资源有效补给,同时减少人类活动对水资源的污染。

【Objective】This study explored distribution characteristics of nitrogen and phosphorus in different wetlands and eutrophication risk in karst basins to provide basis for the protection of wetlands and water resources in karst areas.【Method】Water quality of lake wetlands,marsh wetlands,reservoir wetlands and river wetlands in typical karst basins was monitored during dry,normal and abundant periods.Changes in water nitrogen(TN and NH3-N),phosphorus(TP and PO4^3-P)and dissolved oxygen(DO)concentrations in different wetlands were measured.The logarithmic power function universal index was used to evaluate the eutrophication risk.【Result】The spatial and temporal distribution characteristics of nitrogen and phosphorus concentrations in different wetlands in the Puzhehei karst basin were determined with the highest of meeting the fourth water quality standard in high water periods and the lowest in low water periods.The highest concentrations of TN,NH3-N,TP and PO4^3-P in wetland waters were 1.72,0.95,0.113 and 0.035 mg/L in river wetlands during flood seasons,while the highest concentration of DO was 7.97 mg/L in reservoir wetland during plain seasons.The lowest concentrations of TN,NH3-N,TP and PO4^3-P were 0.18,0.13,0.016 and 0.006 mg/L in lake wetlands during dry seasons.The lowest DO concentration was 4.39 mg/L in swamp wetlands during flood seasons.In different types of wetlands,nitrogen and phosphorus concentrations were in the order of river wetlands>reservoir wetlands>swamp wetlands>lake wetlands.Most wetland water bodies were in the state of moderate nutrition in different periods,belonging to phosphorus limitation.【Conclusion】The eutrophication risk of four wetlands in the Puzhehei karst basin was medium during flood seasons,facing deterioration risk of water quality.Therefore,it is necessary to rationally utilize and protect existing wetlands,ensure the effective recharge of karst water resources,and reduce pollution caused by human activities.