An examination of groundwater discharge and the associated nutrient fluxes into the estuaries of eastern Hainan Island, China using 226Ra.
An examination of groundwater discharge and the associated nutrient fluxes into the estuaries of eastern Hainan Island, China using 226Ra.
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DOI：
10.1016/j.scitotenv.2011.06.017
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发表时间：
2011-09
期刊：
影响因子：
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通讯作者：
Ni Su;Jinzhou Du;W. Moore;Sumei Liu;Jing Zhang
中科院分区：
文献类型：
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作者：
Ni Su;Jinzhou Du;W. Moore;Sumei Liu;Jing Zhang
沿海海湾/河口的营养物浓度和化学计量受到河流直接排放和海底地下水排放（SGD）的强烈影响。为估算海南岛东部巴门湾（BB）和万泉江口（WQ）的海底地下水排放通量，分别于2007年8月和2008年8月在湾/河口采集水样中测定了自然存在的镭同位素（226Ra）。基于226ra在地表水中的分布，采用3端元混合模型估算了各源对这些系统的相对贡献。估计BB和WQ的冲洗时间分别为3.9±2.7和12.9±9.3天，以计算每个系统的镭通量。根据地下水排放的镭通量和地下水样品中的Ra同位素组成，估算出的SGD通量在BB区为3.4±5.0 m3s−1，在WQ区为0.08±0.08 m3s−1，分别占当地河流流量的16%和0.06%。利用这些信息，估算了海底地下水流入BB区和WQ区的养分通量。与来自当地河流的养分通量相比，sgd来源的养分通量在控制研究区，特别是BB区的养分收支和化学计量中发挥了至关重要的作用。
The nutrient concentrations and stoichiometry in a coastal bay/estuary are strongly influenced by the direct riverine discharge and the submarine groundwater discharge (SGD). To estimate the fluxes of submarine groundwater discharge into the Bamen Bay (BB) and the Wanquan River Estuary (WQ) of eastern Hainan Island, China, the naturally occurring radium isotope (226Ra) was measured in water samples collected in the bay/estuary in August 2007 and 2008. Based on the distribution of226Ra in the surface water, a 3-end-member mixing model was used to estimate the relative contributions of the sources to these systems. Flushing times of 3.9 ± 2.7 and 12.9 ± 9.3 days were estimated for the BB and WQ, respectively, to calculate the radium fluxes for each system. Based on the radium fluxes from groundwater discharge and the Ra isotopic compositions in the groundwater samples, the estimated SGD fluxes were 3.4 ± 5.0 m3s−1in the BB and 0.08 ± 0.08 m3s−1in the WQ, or 16% and 0.06%, respectively, of the local river discharge. Using this information, the nutrient fluxes from the submarine groundwater discharge seeping into the BB and WQ regions were estimated. In comparison with the nutrient fluxes from the local rivers, the SGD-derived nutrient fluxes played a vital role in controlling the nutrient budgets and stoichiometry in the study area, especially in the BB.