Are groundwater inputs into river‐dominated areas important? The Chao Phraya River — Gulf of Thailand
Are groundwater inputs into river‐dominated areas important? The Chao Phraya River — Gulf of Thailand
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DOI：
10.4319/lo.2006.51.5.2232
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发表时间：
2006-09
影响因子：
4.5
通讯作者：
H. Dulaiova;W. Burnett;G. Wattayakorn;P. Sojisuporn
中科院分区：
文献类型：
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作者：
H. Dulaiova;W. Burnett;G. Wattayakorn;P. Sojisuporn
我们使用天然地球化学示踪剂氡- 222和镭同位素（223Ra, 224Ra, 226Ra, 228Ra）来评估湄南河与泰国湾之间的交换率，以及河口地下水排放的大小。我们在2004年的两个时期进行了示踪调查，分别是1月（旱季，测量河流流量47立方米s‐1）和7月（雨季，430立方米s‐1）。同位素数据表明，这些示踪剂在河口至少有三种不同的来源：河水、海水和地下水。我们通过使用222Rn、223Ra和224Ra活性以及224Ra: 223Ra比率的混合模型来估计每种输入的程度。我们的分析表明，最大的地下水流出发生在河口附近。我们基于混合模型估算的1月和7月地下水流量分别为10 m3 s - 1和16 m3 s - 1。根据估计的可脱吸镭量，7月份使用过量226Ra的质量平衡以及我们基于224Ra: 223Ra比率估计的水交换率的独立估计得出了14 - 19 m3 s - 1的范围。因此，我们估计的地下水输入在2004年1月低流量时约占河流流量的20%，在7月高流量时占4%。河口附近地区的单位岸线通量（7月约200 m3 m - 1 d - 1）比泰国湾另外两个已评估过地下水通量的地区高出一个数量级以上。
We used the natural geochemical tracers radon‐222 and radium isotopes (223Ra, 224Ra, 226Ra, 228Ra) to assess exchange rates between the Chao Phraya River and the Gulf of Thailand, and the magnitude of groundwater discharge in the estuary. We performed tracer surveys during two periods in 2004, in January (dry season, gauged river discharge 47 m3 s‐1) and in July (wet season, 430 m3 s‐1). The isotopic data suggested that there are at least three different sources of these tracers in the estuary: river water, seawater, and groundwater. We estimated the extent of each input via a mixing model using 222Rn, 223Ra, and 224Ra activities and 224Ra : 223Ra ratios. Our analysis showed that the largest groundwater outflow occurs near the mouth of the river. Our groundwater discharge estimates based on the mixing model are 10 and 16 m3 s‐1 for January and July, respectively. An independent estimate of groundwater discharge in July using a mass balance of excess 226Ra together with our estimated water exchange rates based on 224Ra : 223Ra ratios resulted in a range of 14‐19 m3 s‐1, depending upon the estimated amount of desorbable radium. Our estimated groundwater inputs therefore represent about 20% of the river flow during low flow in January and 4% during high flow conditions in July 2004. The unit shoreline flux (~200 m3 m‐1 d‐1 in July) for the area around the river mouth is over one order of magnitude higher than two other areas of the Gulf of Thailand where groundwater fluxes have been evaluated.