Kaden Ute Susanne, Schulz-Zunkel Christiane, Fuchs Elmar, Horchler Peter, Kasperidus Hans Dieter, de Moraes Bonilha Otavio, Rupp Holger, Tschikof Martin, Weigelhofer Gabriele, Hein Thomas, Scholz Mathias
UFZ Helmholtz Centre for Environmental Research, Department of Conservation Biology and Social-Ecological Systems, Permoserstraße 15, 04318 Leipzig, Germany; BOKU, University of Natural Resources and Life Sciences, Institute of Hydrobiology and Aquatic Ecosystem Management, Gregor-Mendel-Straße 33, 1180 Vienna, Austria.
BfN, Federal Agency for Nature Conservation, Division II 1.4 Nationwide Biodiversity Monitoring and Marine Monitoring, Leipzig Office, Alte Messe 6, 043103 Leipzig, Germany.
Sci Total Environ. 2023 Sep 20;892:164727. doi: 10.1016/j.scitotenv.2023.164727. Epub 2023 Jun 7.
Excess nitrogen (N) from agricultural sources is a major contributor to the water pollution of rivers in Europe. Floodplains are of tremendous importance as they can permanently remove nitrate (NO) from the environment by releasing reactive N to the atmosphere in its gaseous forms (NO, N) during denitrification. However, the quantitative assessment of this ecosystem function is still challenging, particularly on the national level. In this study, we modeled the potential of NO-N removal through microbial denitrification in soils of the active floodplains of the river Elbe and river Rhine in Germany. We combined laboratory measurements of soil denitrification potentials with straightforward modelling data, covering the average inundation duration from six study areas, to improve an existing Germany-wide proxy-based approach (PBAe) on NO-N retention potential. The PBAe estimates this potential to be 30-150 kg NO-N ha yr. However, with soil pH and Floodplain Status Category identified as essential parameters for the proxies, the improved PBA (PBAi) yields a removal potential of 5-480 kg N ha yr. To account for these parameters, we applied scaling factors using a bonus-malus system with a base value of 10-120 N ha yr. Upscaling the determined proxies of the PBAi to the entire active floodplains of the river Elbe and river Rhine results in similarly high NO-N retention sums of ~7000 t yr in spite of very different retention area sizes, strengthening the argument for area availability as the primary objective of restoration efforts. Although PBAs are always subject to uncertainty, the PBAi enables a more differentiated spatial quantification of denitrification because local key controlling parameters are included. Hence, the PBAi is an innovative and robust approach to quantify denitrification in floodplain soils, supporting a better assessment of ecosystem services for decision-making on floodplain restoration.
农业源产生的过量氮（N）是欧洲河流水污染的主要原因。洪泛区非常重要，因为在反硝化过程中，它们可以通过以气态形式（NO、N）向大气释放活性氮，从而永久地从环境中去除硝酸盐（NO）。然而，对这种生态系统功能进行定量评估仍具有挑战性，尤其是在国家层面。在本研究中，我们对德国易北河和莱茵河活跃洪泛区土壤中通过微生物反硝化作用去除NO-N的潜力进行了建模。我们将土壤反硝化潜力的实验室测量结果与直接的建模数据相结合，这些数据涵盖了六个研究区域的平均淹没持续时间，以改进现有的基于代理的全德方法（PBAe）对NO-N保留潜力的评估。PBAe估计这种潜力为30 - 150 kg NO-N·ha·yr。然而，由于土壤pH值和洪泛区状态类别被确定为代理的关键参数，改进后的PBA（PBAi）得出的去除潜力为5 - 480 kg N·ha·yr。为了考虑这些参数，我们使用了一个基准值为10 - 120 N·ha·yr的奖惩系统应用比例因子。尽管易北河和莱茵河的保留面积大小差异很大，但将PBAi确定的代理值扩大到这两条河的整个活跃洪泛区，得出的NO-N保留总量同样高达约7000 t·yr，这进一步证明了将区域可用性作为恢复工作的主要目标的合理性。尽管基于代理的方法总是存在不确定性，但PBAi能够对反硝化作用进行更具差异化的空间量化，因为纳入了局部关键控制参数。因此，PBAi是一种创新且可靠的方法，用于量化洪泛区土壤中的反硝化作用，有助于更好地评估生态系统服务，为洪泛区恢复决策提供支持。
