The focus of this study was to determine the depth-wise variability of physicochemical properties (i.e., pH, TOC, TN, and EC), and heavy metals (i.e., Pb, Cu, Zn, As, and Cr) concentration, and the associated biological and ecological risks of the mangrove sediment. The accumulation of metal contents and the phytoremediation and phytoextraction were also investigated in a mangrove species, Acanthus ilicifolius. The mangrove sediment consists of a higher proportion of sand fraction (56.6–74.7%) followed by clay (10–28%) and silt (10.1–15. 7%) fractions. The concentrations (mg/kg) of Pb, Cu, Zn, As, and Cr were ranged from 22.05–34.3, 8.58–22.77, 85.07–114, 5.56–12.91, and 0.98–5.12 in all the sediment layers. The hierarchy of the mean metal concentration in sediment was Zn (102 mg/kg) > Pb (25.6 mg/kg) > Cu (14.8 mg/kg) > As (8.79 mg/kg) > Cr (2.74 mg/kg) respectively. The examined metal concentrations were below the respective average shale values (ASVs). The degree of environmental, ecological, and biological risks was minimal according to various pollution indices like geoaccumulation index (I_geo), contamination factor (CF), and pollution load index (PLI). According to sediment quality guidelines (SQGs), the adverse biological risk effect was not likely to occur. The result of the potential ecological risk index (PERI) demonstrated that the study area was in the low-risk condition as the corresponded RI value < 100. A combined influence of geogenic and anthropogenic factors was identified as the metal sources by multivariate analysis. The study found that the accumulation rate of the metal contents was higher in leaves than that of roots. The mean descending metal concentration values were Zn (107) > Pb (28. 7) > Cu (16.9) > As (11.2) > Cr (4.99) in leaves and Zn (104.32) > Pb (27.02) > Cu (15.29) > As (10.39) > Cr (3.80) in roots. The translocation and bioaccumulation factors of heavy metals suggested that the mangrove plant species, A. ilicifolius can be used for phytoremediation and phytoextraction since the bio-concentration factor and translocation factor > 1. The studied species exhibited the metal tolerance associated with two following strategies, metal exclusion, and metal accumulation. However, excess metal tolerance can impact the surrounding marine environment.

本研究的焦点是要确定的物理化学性质（的深度方向的变化我。ê。，pH值，TOC，TN，和EC），和重金属（我。ê。，铅，铜，锌，砷，和Cr) 浓度，以及红树林沉积物的相关生物和生态风险。还研究了红树树种Acanthus ilicifolius中金属含量的积累以及植物修复和植物提取. 红树林沉积物由较高比例的砂粒 (56.6–74.7%) 和粘土 (10–28%) 和粉砂 (10.1–15. 7%) 部分组成。在所有沉积层中，Pb、Cu、Zn、As 和 Cr 的浓度（mg/kg）范围为 22.05-34.3、8.58-22.77、85.07-114、5.56-12.91 和 0.98-5.12。沉积物中平均金属浓度的等级分别为 Zn (102 mg/kg) > Pb (25.6 mg/kg) > Cu (14.8 mg/kg) > As (8.79 mg/kg) > Cr (2.74 mg/kg) . 检查的金属浓度低于各自的平均页岩值 (ASV)。根据地累积指数（I _geo）、污染因子（CF）和污染负荷指数（PLI）等各种污染指数，环境、生态和生物风险程度最小。）。根据沉积物质量指南 (SQG)，不太可能发生不利的生物风险效应。潜在生态风险指数（PERI）结果表明研究区处于低风险状态，对应的RI值 < 100。通过多变量分析，地质和人为因素的综合影响被确定为金属来源。研究发现，叶片中金属含量的积累率高于根部。平均下降金属浓度值为 Zn (107) > Pb (28. 7) > Cu (16.9) > As (11.2) > Cr (4.99) 和 Zn (104.32) > Pb (27.02) > Cu (15.29) > 根中的 As (10.39) > Cr (3.80)。重金属的易位和生物富集因子表明红树林植物物种A . 冬青可用于植物修复和植物提取，因为生物浓缩因子和易位因子 > 1。研究的物种表现出与以下两种策略相关的金属耐受性，金属排斥和金属积累。然而，过多的金属耐受性会影响周围的海洋环境。