The denitrification potential of eroding wetlands in Barataria Bay, LA, USA: Implications for river reconnection
The denitrification potential of eroding wetlands in Barataria Bay, LA, USA: Implications for river reconnection
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美国路易斯安那州巴拉塔里亚湾侵蚀湿地的反硝化潜力：对河流重新连接的影响
DOI：
10.1016/j.scitotenv.2019.05.475
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发表时间：
2019
影响因子：
9.8
通讯作者：
White, John R.
中科院分区：
文献类型：
--
作者：
Vaccare, Jessica;Meselhe, Ehab;White, John R.
富营养化的表现形式已导致世界各地沿海生态系统的压力增加。由于氮负荷的增加，沿海湿地生态系统的氮（N）去除潜力是重要的。在路易斯安那州，沿海湿地迅速丧失，主要是由于河流堤坝的存在，隔离了沿海盆地，以及相对较高的海平面上升。生态系统管理人员正在计划建造中巴拉塔里亚沉积物分流，这将重新连接密西西比河与巴拉塔里亚盆地，以建立新的湿地和滋养现有的沼泽。沉积物分流将把大量的硝酸盐输送到巴拉塔里亚湾的表层沃茨。本研究试图量化三个海湾地区的硝酸盐去除潜力;植被沼泽，淹没泥炭边缘，湾底泥质河口沉积物在完整的土芯孵育2毫克L− 1 N-NO3水柱。我们注意到：i）沼泽、边缘和河口区的硝酸盐还原率分别为29.29 ± 3.28、18.83 ± 1.31和10.83 ± 0.62 mg N m− 2 day −1; ii）大部分（~93%）NO3转化为N2 O，表明反硝化作用是NO3还原的主要途径; iii）由于与地表水接触的时间增加，淹没、侵蚀的沼泽土壤（泥炭边缘区）将在硝酸盐还原中发挥重要作用。这些研究结果可以为生态系统管理人员制作和使用的预测数值模型提供信息，以更好地定量了解沿海流域将如何应对河流重连的营养负荷。在更广泛的背景下，路易斯安那州沿海地区目前的相对海平面上升处于海平面上升的范围内，大多数稳定的海岸线将在未来65-85年内经历海平面上升。因此，这些研究结果可以作为一个例子，在未来世纪的潜在影响，全球沿海湿地系统。
Expressions of eutrophication have led to increased stress on coastal ecosystems around the world. The nitrogen (N) removal potential of coastal wetland ecosystems is important due to increased loading of N to the coast. In Louisiana, there is rapid coastal wetland loss due primarily to the presence of river levees, which have isolated the coastal basins, and a high relative sea level rise. Ecosystem managers are planning to construct the Mid-Barataria sediment diversion which will reconnect the Mississippi River with Barataria Basin to build new wetlands and nourish existing marsh. The sediment diversion will deliver large amounts of nitrate into the surface waters of Barataria Bay. This research sought to quantify the nitrate removal potential of three bay zones; vegetated marsh, submerged peat fringe, and bay-bottom muddy estuarine sediment in intact soil cores incubated with a 2 mg L−1N-NO3water column. We noted: i) The areal nitrate reduction rates for the marsh, fringe, and estuary zones were 29.29 ± 3.28, 18.83 ± 1.31, and 10.83 ± 0.62 mg N m−2day−1, respectively; ii) the majority (~93%) of NO3was converted to N2O, indicating denitrification was the major NO3reduction pathway; iii) the submerged, eroded marsh soils (peat fringe zone) will play a large role in nitrate reduction due to increased contact time with the surface water. These findings can inform the predictive numerical models produced and utilized by ecosystem managers to better quantitatively understand how the coastal basin will respond to nutrient loading from river reconnection. In a broader context, the current relative sea level rise in coastal Louisiana is within the range of eustatic sea level rise that most stable coastlines will experience within the next 65–85 years. Therefore, these findings can serve as an example of potential future impacts to coastal wetland systems, globally, within the next century.