^(222)Rn示踪岩溶湿地地下水排泄及氮磷营养盐输入  

Application of radon-222 to assess groundwater discharge and associated nutrients input in the karst wetland

作　　者：张启元 赵雨晴 李远俊 李鑫鹏 ZHANG Qi-yuan;ZHAO Yu-qing;LI Yuan-jun;LI Xin-peng(College of Environmental Science and Engineering,Guilin University of Technology,Guilin,541004;Collaborative Innovation Center for Water Pollution Control and Water Safety in Karst Areas,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学环境科学与工程学院,广西桂林541004 [2]桂林理工大学,岩溶地区水污染控制与用水安全保障协同创新中心,广西桂林541004

出　　处：《中国环境科学》2024年第6期3226-3239,共14页China Environmental Science

基　　金：广西科技基地和人才专项(RZ2100002009,RZ2300150851)。

摘　　要：以会仙湿地八仙湖为研究对象,通过2021年12月(枯水期)和2022年5月(丰水期)的湖水,地下水,沉积物,空气等样品采集,经原位理化性质,氡测量,营养盐等指标的检测,并建立^(222)Rn质量平衡模型,估算八仙湖地下水排泄通量及其营养盐输入.八仙湖^(222)Rn模型的输入项主要为母体226Ra衰变,地下水排泄通量和沉积物扩散量;输出项主要为河流流出通量,湖泊^(222)Rn库衰变量和大气扩散量.通过^(222)Rn质量平衡模型计算得枯水期八仙湖地下水排泄速率约为(110.60±23.75)mm/d,丰水期湖中地下水排泄速率为(238.04±46.58)mm/d.然后通过八仙湖周边地下水平均营养盐浓度,估算枯水期地下水排泄营养盐输入为NH_(4)^(+)-N(2.24±0.52)×10^(-3)mol/(m^(2)·d),NO_(3)^(-)-N(1.93±0.42)×10^(-2)mol/(m^(2)·d),TN(1.20±0.26)×10^(-1)mol/(m^(2)·d),TP(1.97±0.42)×10^(-4)mol/(m^(2)·d);丰水期地下水排泄营养盐输入为NH_(4)^(+)-N(1.30±0.25)×10^(-2)mol/(m^(2)·d),NO_(3)^(-)-N(2.71±0.53)×10^(-2)mol/(m^(2)·d),TN(2.18±0.43)×10^(-1)mol/(m^(2)·d),TP(4.51±0.89)×10^(-4)mol/(m^(2)·d).本研究结果揭示地下水排泄给八仙湖环境带来的影响是不能忽略的,因此在治理会仙湿地环境时应重视地下水排泄对湿地水环境污染的贡献,以期为湿地水资源评价提供基础数据.Baxian Lake,located in Huixian Wetland,was taken as the study’s object in this paper to investigate the groundwater discharge flux and the associated nutrient input.The samples of lake water,groundwater,sediments,and air collected in December 2021(dry season)and May 2022(wet season)were tested for physical and chemical properties,^(222)Rn and nutrients.The input items of^(222)Rn in Baxian Lake were 226Ra parent decay,sediment diffusion,and groundwater discharge.The output items included the runoff flux,decay of^(222)Rn inventory in the lake,and atmospheric diffusion.Then,the^(222)Rn mass balance model of Baxian Lake was established,and the groundwater discharge rate during the dry season and the rainy season were 110.60±23.75mm/d and 238.04±46.58mm/d,respectively.Based on the average nutrient concentration of groundwater around Baxian Lake,the nutrients flux from the groundwater discharge during the dry season were estimated as follows:(2.24±0.52)×10^(-3)mol/m^(2)×d(NH_(4)^(+)-N),(1.93±0.42)×10^(-2)mol/(m^(2)⋅d)(NO_(3)^(-)-N),(1.20±0.26)×10^(-1)mol/(m^(2)⋅d)(TN),(1.97±0.42)×10^(-4)mol/(m^(2)⋅d)(TP).The nutrient fluxes from the groundwater discharge during the wet season were:(1.30±0.25)×10^(-2)mol/(m^(2)⋅d)(NH_(4)^(+)-N),(2.71±0.53)×10^(-2)mol/(m^(2)⋅d)(NO_(3)^(-)-N),(2.18±0.43)×10^(-1)mol/(m^(2)⋅d)(TN),(4.51±0.89)×10^(-4)mol/(m^(2)⋅d)(TP).This study provides important information for water circulation and water ecosystem for the water resource management of Huixian Wetland.

关 键 词：会仙岩溶湿地 氡同位素 地下水排泄 营养盐输入 

分 类 号：X52[环境科学与工程—环境工程]