Developing a salinity-based approach for the evaluation of DIN removal rate in estuarine ecosystems
Developing a salinity-based approach for the evaluation of DIN removal rate in estuarine ecosystems
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开发基于盐度的方法来评估河口生态系统中的 DIN 去除率
DOI：
10.1007/s10646-015-1478-9
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发表时间：
2015-10-01
期刊：
影响因子：
2.7
通讯作者：
Wang, Youshao
中科院分区：
文献类型：
--
作者：
Hong, Yiguo;Wang, Shuailong;Wang, Youshao
河口在去除过量氮以缓解沿海海水富营养化压力方面发挥着重要作用。然而，由于河流水与沿海海水之间复杂的动态混合过程，很难估计河口生态系统中氮的确切去除量。在本研究中，基于相对盐度可以作为混合程度指标的假设，开发了一种计算河口水体中溶解无机氮（DIN）去除率的新方法。这一假设得到了实验结果的支持，实验结果表明DIN的下降与盐度的增加之间存在线性回归关系，因此可以用盐度作为指标来确定稀释效应导致的混合水中DIN的减少。利用该模型定义了切萨皮克湾和珠江口的DIN去除率。正如预测的那样，我们的分析表明，两个研究河口的DIN去除率从上游到下游逐渐增加，并且具有明显的季节变化规律：暖季高，冷季低。该方法的实际应用可能受到多种因素的影响，包括河口地理地貌、河口初始DIN浓度、海水中DIN浓度、支流进口DIN、污水排放和水动力混合等。因此，这些结果支持了河口对人类活动输入的氮具有较强的去除能力，特别是在温暖季节，因此在调节全球氮生物地球化学循环平衡中应发挥重要作用的假设。
Estuaries play an important role in the removal of overloading nitrogen to relieve the eutrophic pressure of coastal seawater. However, the exact amount of nitrogen removed in estuarine ecosystems is difficult to be estimated because of the complex dynamic mixing process between riverine water and coastal seawater. In this study, a new method was developed to calculate the removal rate of dissolved inorganic nitrogen (DIN) in estuarine waters attributed to the mixing process and was based on the assumption that relative salinity can serve as an indicator of the degree of mixing. This assumption was supported by the experimental results that demonstrated a linear regression relationship between DIN decline and salinity increase Thus, the decreased amount of DIN in mixing waters attributed to the dilution effect could be determined with the salinity as an index. With this model, the DIN removal rate in both Chesapeake Bay and Pearl River Estuary were defined. As predicted, our analysis demonstrated that the DIN removal rate increased gradually from upstream to downstream in both studied estuaries with obvious seasonable variation pattern: high in warm seasons and low in cold seasons. The practical application of this method might be affected by multiple factors, including the geographic landform of estuaries, initial estuaries DIN concentration, the DIN concentration in seawater, DIN importing from tributaries, sewage discharge and hydrodynamic mixing. Therefore, the results supported the hypothesis that estuaries have a strong capability to remove the nitrogen inputted from human activities, especially in warm season and therefore should play an important role in regulating the balance of global nitrogen biogeochemical cycle.