Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, China.
Chemosphere. 2021 May;270:128665. doi: 10.1016/j.chemosphere.2020.128665. Epub 2020 Oct 21.
Nitrogen (N) and phosphorus (P) are vital nutrients regulating mangrove productivity and coastal ecosystems. Understanding of the nutrient cycling and interaction between mangroves and estuary is limited. Here we show tidal-driven nutrient exchange and a dynamic source-sink pattern across the mangrove-estuary interface. Lateral nutrient fluxes were quantified based on hourly concentrations observed at a tidal creek outlet during 2016-2018 and water mass estimated by a hydrodynamic model (FVCOM). The results of nutrient fluxes suggested that mangroves always serve as a source of ammonium (NH-N) and dissolved reactive P (DRP) to estuary, but as a strong nitrate sink (NO-N). Dissolved organic components (DON and DOP) shifted from net efflux (source) in spring to net influx (sink) in summer, likely due to the changing balance of P input and biological and physicochemical processes. Mangroves decreased the overall loading of dissolved inorganic N (DIN), dissolved total N (DTN) and total P (TP) to the estuary. Nevertheless, the effluents (aquaculture wastewater and domestic sewage) discharged from the upstream area during ebb tide increased the export of nutrients, especially NH-N and DRP, offsetting the role of mangrove on mitigating coastal eutrophication.
氮（N）和磷（P）是调节红树林生产力和沿海生态系统的重要营养物质。然而，人们对红树林与河口之间的养分循环和相互作用的理解有限。本研究展示了潮汐驱动的养分交换和红树林-河口界面的动态源-汇格局。基于 2016 年至 2018 年期间在潮汐溪出口处每小时观测到的浓度和水动力模型（FVCOM）估算的水团，定量了侧向养分通量。养分通量的结果表明，红树林始终是铵（NH-N）和溶解活性磷（DRP）向河口的源，但却是硝酸盐的强汇（NO-N）。溶解有机成分（DON 和 DOP）在春季从净流出（源）转变为夏季的净流入（汇），这可能是由于磷输入和生物及物理化学过程的平衡变化。红树林减少了向河口输送的溶解无机氮（DIN）、溶解总氮（DTN）和总磷（TP）的总量。然而，在退潮期间，上游地区排放的废水（养殖废水和生活污水）增加了养分的输出，尤其是 NH-N 和 DRP，抵消了红树林在减轻沿海富营养化方面的作用。
