Wang Lin, Shang Songhao, Liu Wenzhi, She Dongli, Hu Wei, Liu Yi
State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China.
Water Res. 2023 Aug 15;242:120257. doi: 10.1016/j.watres.2023.120257. Epub 2023 Jun 21.
The impact of nitrogen (N) on water eutrophication is well-known, but the specific influence of hydrodynamic factors on N occurrence in aquatic systems has remained unclear. This lack of understanding has hindered our ability to assess the self-purification function of aquatic ecosystems and address water pollution problem. Here, we collected overlying water and sediment samples from different aquatic ecosystems (ditch, pond, river, and reservoir) in the Danjiangkou Reservoir area and compared the variation characteristics of various N components, and further conducted an incubation experiment to investigate the rate of N removal. We found that the concentration of total N and its N components decreased from ditches and ponds to rivers and reservoirs, indicating that N removal occurred during water flow, with up to 43% of total N concentration reduction rate. Additionally, we observed higher heterogeneity in eco-stoichiometric characteristics of N components in ditches and ponds compared to rivers and reservoirs. Interestingly, the ditches and ponds exhibited stronger interactions between overlying water and sediment, with higher rates of denitrification and anaerobic ammonium oxidation (anammox). Our findings highlight the need to focus on the upper reaches of agricultural catchments, such as ditches and ponds, for N removal and emphasize the importance of developing region-specific conservation strategies to mitigate N pollution and protect water resources.
氮（N）对水体富营养化的影响众所周知，但水动力因素对水生系统中氮存在形式的具体影响仍不清楚。这种认识上的不足阻碍了我们评估水生生态系统自净功能和解决水污染问题的能力。在此，我们从丹江口水库地区不同水生生态系统（沟渠、池塘、河流和水库）采集了上覆水和沉积物样本，比较了各种氮组分的变化特征，并进一步进行了孵化实验以研究氮的去除率。我们发现，总氮及其氮组分的浓度从沟渠和池塘到河流和水库逐渐降低，这表明在水流过程中发生了氮的去除，总氮浓度降低率高达43%。此外，我们观察到，与河流和水库相比，沟渠和池塘中氮组分的生态化学计量特征具有更高的异质性。有趣的是，沟渠和池塘中，上覆水与沉积物之间的相互作用更强，反硝化和厌氧氨氧化（anammox）速率更高。我们的研究结果突出了需要关注农业集水区的上游区域，如沟渠和池塘，以去除氮，并强调制定因地制宜的保护策略对于减轻氮污染和保护水资源的重要性。
