ISSN 1000-3665 CN 11-2202/P

    红树林潮沟地下水营养盐分布特征及其排泄通量研究

    Spatial distribution and groundwater discharge fluxes of nutrients in a mangrove tidal creek

    • 摘要: 潮沟是红树林湿地地表水-地下水交换及物质输运的关键通道,但目前关于潮沟地下水中营养盐的空间分布特征及其驱动机制仍不明确。本研究在广东省海陵岛红树林潮沟系统的上游和下游选取了2个典型剖面,通过地下水水位监测与分层取样,采用多元统计分析法探讨了营养盐分布的影响因素,计算了地表水-地下水交换速率及其携带营养盐通量,并系统对比了全球红树林区海底地下水排泄(submarine groundwater discharge, SGD)营养盐通量的多尺度格局。潮沟下游地下水排泄速率及其携带的溶解态无机氮(Dissolved inorganic nitrogen, DIN)、溶解态无机磷(Dissolved inorganic phosphorus, DIP)和溶解态硅酸盐(Dissolved silicate, DSi)通量均高于上游,且大小顺序均为DSi>DIN>DIP。此外,潮沟底部和潮沟岸的理化参数和营养盐呈现出明显的空间分异分布特征。该模式主要受控于潮汐驱动的地下水排泄、盐度驱动的密度流和生物地球化学反应的共同调控。全球数据对比显示,红树林区是SGD(中位数为9.0 cm/d)及其携带的DSi中位数为36.74 mmol/(m2·d)和DIP通量中位数为0.21 mmol/(m2·d)的热点区域,而DIN通量中位数为1.95 mmol/(m2·d)相对较低。此外,红树林区不同尺度的SGD速率及其携带营养盐通量具有显著差异。本研究为深入理解潮沟系统营养盐的迁移转化行为,同时为红树林湿地生态系统保护与近岸环境管理提供科学依据。

       

      Abstract: Tidal creeks serve as critical conduits for surface water-groundwater exchange and material transport in mangrove wetlands. However, the spatial distribution patterns of nutrients in groundwater and the underlying driving mechanisms remain poorly understood. In this study, two representative cross-sectional profiles (upstream and downstream) along a typical tidal creek system in the Hailing Island mangrove wetland, Guangdong Province, were investigated. Groundwater level monitoring, stratified groundwater sampling, and multivariate statistical analysis were combined to characterize nutrient distributions, quantify surface water-groundwater exchange rates and associated nutrient fluxes, and place the results in a global context through a comparative synthesis of the multi-scale patterns of submarine groundwater discharge (SGD) associated nutrient fluxes across mangrove regions. The groundwater discharge rate was higher downstream than upstream, and the fluxes of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicate (DSi) carried by groundwater discharge were also higher downstream than upstream, following the order DSi > DIN > DIP. Additionally, physicochemical parameters and nutrients exhibited clear spatial differentiation between the tidal creek bottom and its banks. This spatial pattern was mainly driven by tidally driven groundwater discharge, salinity-induced density flow, and biogeochemical reactions. Global data comparison indicated that mangrove areas were hotspots for SGD (median = 9.0 cm/d) and associated DSi median = 36.74 mmol/(m2·d) and DIP fluxes median = 0.21 mmol/(m2·d), while DIN flux median = 1.95 mmol/(m2·d) was relatively low. Additionally, significant differences existed in SGD rates and associated nutrient fluxes across different scales in mangrove areas. This study advances the understanding of nutrient transport and transformation processes in tidal creek systems, and provides a scientific basis for mangrove wetland conservation and coastal environmental management.

       

    /

    返回文章
    返回