Liang Xiuqiong, Liu Chunxiang, Wang Haoyu, Li Haonan, Luo Jin, Luo Gang, Hu Wei, Lan Wenlu, Wu Leishi, Fang Sheng, Tian Yan, Sun Xiang
College of Resources, Environment and Materials, Guangxi University, Guangxi, Nanning, 530004, China.
Marine Environmental Monitoring Center of Guangxi, Guangxi, Beihai, 536000, China.
Environ Pollut. 2025 Jun 15;375:126354. doi: 10.1016/j.envpol.2025.126354. Epub 2025 May 1.
Mangrove areas are the major sink of pollutants such as microplastics (MPs, less than 5000 μm in diameter). The spatial retention, transport, and accumulation of microplastics (MPs) within the complex mangrove sediment system has become a hotspot in the field of emerging contaminants. In this study, the Xiaoguansha mangrove forest in Guangxi Province, China, was selected as a representative case to investigate the horizontal and vertical distribution of MPs in sediments. To elucidate the processes of MP retention, accumulation, and their downward transport into deeper soil layers, a combination of statistical methods was employed, including the Kruskal-Wallis one-way ANOVA, correlation analysis, regression fitting, and Structural Equation Model (SEM). The results showed that: (1) The average abundance of MPs in the mangrove area (2414.0 ± 1570.8 items/kg) was significantly higher-by a factor of 2.24-than that in the tidal flat areas, suggesting that mangroves play a vital role in seawater purification.(2) The MPs in the smaller size range (0-1000 μm) tend to accumulate more readily in mangrove areas compared to larger particles (1000-5000 μm), implying a heightened potential risk to environmental and ecosystem health.(3) With the increase in soil depth, exhibited an exponentially decreasing trend, primarily due to the well-developed root systems of mangroves and the physicochemical adsorption capacity of the surrounding sediments. (4) Spatial retention and sediment absorption contributed 67.2 % and 32.8 %, respectively, to the enrichment of MPs in mangrove areas. The SEM analysis confirmed that the distribution of MPs was primarily governed by extensive root system and dense physical structure of mangrove. In addition, adsorption effects driven by the fundamental physicochemical properties of the sediments also contributed to MP retention. The findings contribute to a deeper understanding of the behavior of MPs in the mangrove-covered water-sediment system.
红树林区域是微塑料（直径小于5000微米的 MPs）等污染物的主要汇。微塑料在复杂的红树林沉积物系统中的空间滞留、迁移和积累已成为新兴污染物领域的研究热点。本研究选取中国广西小关沙红树林作为典型案例，调查沉积物中微塑料的水平和垂直分布。为阐明微塑料的滞留、积累过程及其向下迁移至更深土层的过程，采用了多种统计方法，包括Kruskal-Wallis单因素方差分析、相关性分析、回归拟合和结构方程模型（SEM）。结果表明：（1）红树林区域微塑料的平均丰度（2414.0±1570.8个/千克）显著高于潮滩区域，高出2.24倍，表明红树林在海水净化中发挥着至关重要作用。（2）与较大颗粒（1000 - 5000微米）相比，较小尺寸范围（0 - 1000微米）的微塑料在红树林区域更容易积累，这意味着对环境和生态系统健康的潜在风险更高。（3）随着土壤深度增加，呈指数下降趋势，主要原因是红树林发达的根系和周围沉积物的物理化学吸附能力。（4）空间滞留和沉积物吸附分别对红树林区域微塑料的富集贡献了67.2%和32.8%。结构方程模型分析证实，微塑料的分布主要受红树林广泛的根系和密集的物理结构控制。此外，沉积物基本物理化学性质驱动的吸附作用也有助于微塑料的滞留。这些发现有助于更深入地了解微塑料在红树林覆盖的水 - 沉积物系统中的行为。
