Department of Soil, Water and Environment, University of Dhaka, Dhaka, 1000, Bangladesh.
Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, 27695, USA.
Sci Rep. 2022 Jun 21;12(1):10422. doi: 10.1038/s41598-022-13609-z.
At present, there are growing concerns over the increasing release of trace metals in the Sundarbans mangrove areas in Bangladesh due to nearby shipbreaking and metallurgical industries, untreated waste discharge, navigation activities, and other natural processes that deposit trace metals into soils. The current study investigated the spatial distribution, contamination level, and ecotoxicity of eight trace metals (Fe, Mn, Cu, Zn, Pb, Cd, Cr, Ni) in Sundarbans soils. Results revealed that all the trace metals except Cr were present in higher concentrations compared to Earth's shale and/or upper continental crust. Principal component analysis and Pearson correlation showed strong positive correlations (p < 0.05) between Fe, Mn, Cu, and Zn; Ni with Mn and Cr. There were significant associations (p < 0.05) of % clay and total organic carbon (TOC) with Pb-Ni-Cr and negative correlations of pH with all the trace metals. The hierarchical cluster analysis grouped Pb, Ni, and Cd into one distinct cluster, suggesting they are derived from the same sources, possibly from anthropogenic activities. Geo accumulation index (I-geo), enrichment factor (EF), contamination factor (CF), and spatial distribution showed moderately polluted soils with Ni, Pb, and Cd (EF = 3-7.4, CF = 1-2.8, I-geo = 0-0.9) and low pollution by Zn, Cu, Fe, and Mn (EF < 3, CF < 1, I-geo < 0). The ecological risk index (RI) revealed that S-4 (RI = 114.02) and S-5 (RI = 100.04) belonged to moderate risk, and other areas posed a low risk (RI < 95). The individual contribution of Cd (25.9-73.7%), Pb (9.2-29.1%), and Ni (9.6-26.4%) to RI emphasized these metals were the foremost concern in the Sundarbans mangroves due to their long persistence time and high toxicity, even if they were present in low concentrations.
目前，由于附近的船舶拆解和冶金行业、未经处理的废物排放、航行活动以及其他将痕量金属沉积到土壤中的自然过程，孟加拉国孙德尔本斯红树林地区痕量金属的释放量不断增加，引起了人们越来越多的关注。本研究调查了孙德尔本斯土壤中八种痕量金属（Fe、Mn、Cu、Zn、Pb、Cd、Cr、Ni）的空间分布、污染水平和生态毒性。结果表明，除 Cr 以外的所有痕量金属的浓度均高于地球页岩和/或上地壳。主成分分析和 Pearson 相关性表明，Fe、Mn、Cu 和 Zn 之间存在强烈的正相关（p<0.05）；Ni 与 Mn 和 Cr 之间存在强烈的正相关。%粘土和总有机碳（TOC）与 Pb-Ni-Cr 之间存在显著关联（p<0.05），而 pH 与所有痕量金属之间存在负相关。层次聚类分析将 Pb、Ni 和 Cd 分为一个独特的聚类，表明它们来自相同的来源，可能来自人为活动。地积累指数（I-geo）、富集因子（EF）、污染因子（CF）和空间分布显示，Ni、Pb 和 Cd 污染程度中等（EF=3-7.4，CF=1-2.8，I-geo=0-0.9），Zn、Cu、Fe 和 Mn 污染程度较低（EF<3，CF<1，I-geo<0）。生态风险指数（RI）显示，S-4（RI=114.02）和 S-5（RI=100.04）属于中度风险，其他地区属于低风险（RI<95）。Cd（25.9-73.7%）、Pb（9.2-29.1%）和 Ni（9.6-26.4%）对 RI 的单独贡献强调了这些金属是孙德尔本斯红树林地区最主要的关注点，因为它们的持久性长且毒性高，即使它们的浓度较低。
