长湖地下水排泄及其携带营养盐通量的季节性变化  

Seasonal variations in groundwater discharge and associated nutrient fluxes in Changhu Lake

作　　者：吴婧 甘义群 杜尧 孙晓梁 韩鹏 WU Jing;GAN Yiqun;DU Yao;SUN Xiaoliang;HAN Peng(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China)

机构地区：[1]中国地质大学(武汉)环境学院,武汉430078

出　　处：《地质科技通报》2024年第5期206-215,共10页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目(U21A2026)。

摘　　要：为揭示地下水对湖泊水量和营养盐平衡的贡献及季节性变化,以长江中游的长湖为研究对象,通过丰、枯水期野外采样,结合电导率(EC)、稳定同位素(~2H和^(18)O)、水化学元素(Ca^(2+)、Mg^(2+))和氡(^(222)Rn)同位素对湖底地下水排泄(lacustrine groundwater discharge,简称LGD)进行了多手段示踪,并基于^(222)Rn质量平衡模型量化了不同季节的LGD及其携带的营养盐通量。结果显示:丰、枯水期LGD速率分别为64.52 mm/d和14.95 mm/d,丰水期显著大于枯水期;丰、枯水期地下水携带的总氮(TN)输入通量分别为25.68×10^(6) g/d和5.58×10^(6) g/d,总磷(TP)输入通量分别8.14×10^(6) g/d和0.17×10^(6) g/d。丰、枯水期LGD强度的差异导致了地下水携带TN、TP输入的差异,丰水期TP的输入量还受该时期农业活动的影响;丰水期较强的降水和蒸发驱动了更大的LGD强度及其携带的TN、TP通量。本研究可为长湖区域水资源管理和水生态保护提供重要理论依据。[Objective]To assess contribution and seasonal variation in groundwater discharge(LGD)to lake water and nutrient budgets,[Methods]this study investigated Changhu Lake in the middle reaches of the Yangtze River.Field sampling was conducted during both the wet and dry seasons using multiple tracing techniques,including electrical conductivity(EC),stable isotope(2H and 18 O),hydrochemical element(Ca_(2)+and Mg 2+),and 222 Rn isotope data.The 222 Rn mass balance model was employed to quantify the LGD and associated nutrient fluxes in different seasons.[Results]Results show that LGD rates during the wet and dry seasons were 64.52 mm/d and 14.95 mm/d,respectively,with significant differences between these seasons.Furthermore,during the wet and dry seasons,groundwater carried TN inputs of approximately 25.68×10^(6) g/d and 5.58×10^(6) g/d,respectively.The TP inputs were approximately 8.14×10^(6) g/d and 0.17×10^(6) g/d in the wet and dry seasons,respectively.The differences in the LGD rates between the wet and dry seasons lead to differences in groundwater carrying TN and TP inputs,and inputs of TP during the wet season is also influenced by agricultural activities during that period.Sronger precipitation and evaporation during the wet season drive greater LGD intensity and their carrying TN and TP fluxes.[Conclusion]The research can provide scientific reference for water resource management and aquatic ecosystem preservation efforts in the Changhu area.

关 键 词：湖泊 地下水排泄 氡质量平衡模型 氮 磷 营养盐通量 季节性变化 

分 类 号：P641.2[天文地球—地质矿产勘探] X143[天文地球—地质学]