珠江口潜水镭同位素时空特征及其对海底地下水排泄通量测算的影响研究  

Temporal and spatial characteristics of radium isotope in phreatic water in the Pearl River Estuary and their influence on the calculation of submarine groundwater discharge fluxes

作　　者：吴才华 张泽彬 王亚 周永章 朱雅敏[5] 赵新锋 李清洋 李镇雄 Wu Cai-hua;Zhang Ze-bin;Wang Ya;Zhou Yong-zhang;Zhu Ya-min;Zhao Xin-feng;Li Qing-yang;Li Zhen-xiong(School of Earth Science and Engineering,Sun Yat-sen University,Zhuhai Guangdong 519082,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai Guangdong 519082,China;Key Laboratory of Geological Process and Mineral Resources Exploration in Guangdong Province,Guangzhou 510275,China;Zhuhai Eco-Environmental Monitoring Station of Guangdong province,Zhuhai Guangdong 519070,China;Zhuhai Ocean Center,Ministry of Natural Resources,Zhuhai Guangdong 519015,China)

机构地区：[1]中山大学地球科学与工程学院,广东珠海519082 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [3]广东省地质过程与矿产资源探查重点实验室,广州510275 [4]广东省珠海生态环境监测站,广东珠海519070 [5]自然资源部珠海海洋中心,广东珠海519015

出　　处：《矿物岩石地球化学通报》2024年第3期541-552,共12页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41602253,U1911202);南方海洋科学与工程广东省实验室(珠海)创新团队建设项目(311023004)。

摘　　要：准确选取具有代表性的地下水端元是采用镭同位素示踪法量化海底地下水排泄(SGD)通量的关键。本研究分析了珠江三角洲潜水^(224)Ra与^(223)Ra的时空分布特征,评估了其对SGD通量计算的影响。结果表明,从潮间带近端至远端,潮间带潜水盐度和镭活度总体上表现为先下降后升高;相近盐度下,不同潮滩潮间带潜水镭活度无量级差别,仅随盐度上升的变化趋势略有差异;河口内外潮间带潜水的^(224)Ra活度最大相差(1986.8±94.5)dpm/100L,导致测算的SGD差异可达(25.2±9.6)×10^(8)m^(3)/d;以砂质潮滩为例,测算的旱、雨季SGD通量差异可达(2.3±1.6)×10^(8)m^(3)/d。SGD通量对潜水端元取值的敏感性分析显示,盐度影响最大,季节影响次之,潮滩性质影响最小。因此选择镭同位素趋近解吸平衡的高盐度潮间带潜水作为代表性潜水端元进行SGD通量测算较为合理。Accurate selection of representative groundwater end-members is critical for quantifying submarine groundwater discharge(SGD)fluxes using radium isotope tracers.This study analyzed temporal and spatial distribution characteristics of ^(224)Ra and ^(223)Ra in the phreatic water of the Pearl River Delta,and assessed its impact on SGD fluxe calculation.The results showed that from the near end to the far end of the intertidal zone,both the salinity and radium activity of the intertidal phreatic water tended to firstly decrease and then increase.Under similar salinity,there is no order of magnitude difference in the activity of radium in the intertidal phreatic water of different tidal flats,and only a slight difference in the trend of change with increasing salinity.The maximum difference of ^(224)Ra activity in the intertidal phreatic water inside and outside the estuary is(1986.8±94.5)dpm/100L,leading to an SGD variance of up to(25.2±9.6)×10^(8)m^(3)/d.Taking sandy tidal flat as an example,the calculated difference of SGD flux in dry season and rainy season is as high as(2.3±1.6)×10^(8)m^(3)/d.Sensitivity analysis of SGD flux on phreatic water end-member selection showed that salinity has the greatest impact,followed by seasonality,and tidal flat properties have the least impact.Therefore,it is more reasonable to choose high salinity intertidal phreatic water that is close to reaching the radium desorption equilibrium as the representative phreatic water end-member for SGD flux calculation.

关 键 词：镭同位素 镭质量平衡模型 盐度 潜水端元 潮间带潜水 

分 类 号：P641.3[天文地球—地质矿产勘探]