Hasan Md Rakibul, Anisuzzaman Md, Choudhury Tasrina Rabia, Arai Takaomi, Yu Jimmy, Albeshr Mohammed Fahad, Hossain M Belal
Department of Fisheries and Marine Science, Noakhali Science and Technology University, Noakhali 3814, Bangladesh.
Analytical Chemistry Laboratory, Chemistry Division, Atomic Energy Centre, Dhaka 1000, Bangladesh.
Mar Pollut Bull. 2023 Apr;189:114804. doi: 10.1016/j.marpolbul.2023.114804. Epub 2023 Mar 14.
Understanding the vertical distribution of heavy metals aids in tracing the contamination history, however, it is limited for mangrove-dominated river. Thus, this study aimed to assess the vertical distribution of nine heavy metals and their possible ecological risk in several layers of core sediments from a mangrove-dominated river inside the Sundarban mangrove forest (World heritage and Ramsar site), Bangladesh. 45 core samples from five stations were analyzed using Flame Atomic Absorption Spectrophotometer (FAAS). The findings showed that, with the exception of Fe, Ni, and Cu, which suggested increased metal release in recent times, higher metal levels were recorded in the surface layer (0-10 cm), followed by the middle layer (10-20 cm), and inner layer (20-30 cm) of sediment cores. When compared to non-industrial forest sediment, core sediment from industrial sites contained noticeably more metals (p < 0.05). Overall, the mean metal concentration (mg/kg) followed the increasing order of Cd < As < Pb < Cu < Cr < Zn < Ni < Mn < Fe. Among the studied metals, the levels of Cd and Ni exceeded the average shale value. Contamination indices such as enrichment factor (EF), contamination factor (CF), and geo-accumulation index (I) showed that the studied sediments were only contaminated by Cd. Ecological risk assessed by ecological risk factor (E) and risk index (RI) suggested that the analyzed heavy metals, with the exception of Cd, posed no significant ecological threats. All of the heavy metals analyzed might have originated from similar anthropogenic sources, according to the correlation matrix, cluster analysis (CA), and principal component analysis (PCA).
了解重金属的垂直分布有助于追溯污染历史，然而，这对于以红树林为主的河流来说是有限的。因此，本研究旨在评估孟加拉国孙德尔本斯红树林森林（世界遗产和拉姆萨尔湿地）内一条以红树林为主的河流的几个核心沉积物层中九种重金属的垂直分布及其可能的生态风险。使用火焰原子吸收分光光度计（FAAS）对来自五个站点的45个核心样本进行了分析。研究结果表明，除了铁、镍和铜显示近期金属释放增加外，在沉积物核心的表层（0 - 10厘米）记录到较高的金属含量，其次是中层（10 - 20厘米）和内层（20 - 30厘米）。与非工业森林沉积物相比，工业站点的核心沉积物含有明显更多的金属（p < 0.05）。总体而言，平均金属浓度（毫克/千克）的递增顺序为镉 < 砷 < 铅 < 铜 < 铬 < 锌 < 镍 < 锰 < 铁。在所研究的金属中，镉和镍的含量超过了页岩平均含量。诸如富集因子（EF）、污染因子（CF）和地累积指数（I）等污染指数表明，所研究的沉积物仅受到镉的污染。通过生态风险因子（E）和风险指数（RI）评估的生态风险表明，除镉外，分析的重金属没有构成重大生态威胁。根据相关矩阵、聚类分析（CA）和主成分分析（PCA），所有分析的重金属可能都来自类似的人为来源。
