Department of Coastal Environment Dynamics (DYNECO), French Research Institute for Exploration of the Sea (IFREMER), Centre de Bretagne, B.P. 70, 29280 Plouzané, France.
Royal Belgian Institute of Natural Sciences (RBINS), Operational Directorate Natural Environments (DO Nature), Gulledelle 100, 1200 Brussels, Belgium.
Sci Total Environ. 2018 Jul 1;628-629:400-414. doi: 10.1016/j.scitotenv.2018.02.025. Epub 2018 Feb 13.
Since 1950, increase in nitrogen (N) and phosphorus (P) river loadings in the North-East Atlantic (NEA) continental seas has induced a deep change in the marine coastal ecosystems, leading to eutrophication symptoms in some areas. In order to recover a Good Ecological Status (GES) in the NEA, as required by European Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD), reductions in N- and P-river loadings are necessary but they need to be minimal due to their economic impact on the farming industry. In the frame of the "EMoSEM" European project, we used two marine 3D ecological models (ECO-MARS3D, MIRO&CO) covering the Bay of Biscay, the English Channel and the southern North Sea to estimate the contributions of various sources (riverine, oceanic and atmospheric) to the winter nitrate and phosphate marine concentrations. The various distributed descriptors provided by the simulations allowed also to find a log-linear relationship between the 90th percentile of satellite-derived chlorophyll concentrations and the "fully bioavailable" nutrients, i.e. simulated nutrient concentrations weighted by light and stoichiometric limitation factors. Any GES threshold on the 90th percentile of marine chlorophyll concentration can then be translated in maximum admissible 'fully bioavailable' DIN and DIP concentrations, from which an iterative linear optimization method can compute river-specific minimal abatements of N and P loadings. The method has been applied to four major river groups, assuming either a conservative (8μgChlL) or a more socially acceptable (15μgChlL) GES chlorophyll concentration threshold. In the conservative case, maximum admissible winter concentrations for nutrients correspond to marine background values, whereas in the lenient case, they are close to values recommended by the WFD/MSFD. Both models suggest that to reach chlorophyll GES, strong reductions of DIN and DIP are required in the Eastern French and Belgian-Dutch river groups.
自 1950 年以来，东北大西洋（NEA）沿海海域氮（N）和磷（P）河流负荷的增加导致了海洋沿海生态系统的深刻变化，导致一些地区出现富营养化症状。为了恢复东北大西洋的良好生态状况（GES），正如欧洲水框架指令（WFD）和海洋战略框架指令（MSFD）所要求的那样，减少 N 和 P 河流负荷是必要的，但由于它们对农业产业的经济影响，这种减少需要最小化。在“EMoSEM”欧洲项目的框架内，我们使用了两个海洋 3D 生态模型（ECO-MARS3D、MIRO&CO）来覆盖比斯开湾、英吉利海峡和北海南部，以估计各种来源（河流、海洋和大气）对冬季硝酸盐和磷酸盐海洋浓度的贡献。模拟提供的各种分布式描述符还允许在卫星衍生的叶绿素浓度的第 90 百分位数和“完全生物可利用”营养素之间找到对数线性关系，即根据光和化学计量限制因子对模拟营养素浓度进行加权。然后，可以将任何 GES 阈值转换为海洋叶绿素浓度的第 90 百分位数的最大允许“完全生物可利用”DIN 和 DIP 浓度，从中可以通过迭代线性优化方法计算出特定河流的 N 和 P 负荷的最小减排量。该方法已应用于四个主要的河流群，假设 GES 叶绿素浓度的阈值为保守值（8μgChlL）或更能被社会接受的值（15μgChlL）。在保守情况下，冬季营养素的最大允许浓度对应于海洋背景值，而在宽松情况下，它们接近 WFD/MSFD 建议的值。两种模型都表明，为了达到叶绿素 GES，法国东部和比荷卢经济联盟的河流群需要大幅减少 DIN 和 DIP。
