ABSTRACT

Selective accumulation of heavy metals in mangrove plant parts have been reported earlier; however, varying heavy metal accumulation in the sediments adjacent to different mangrove plant species is rarely reported. We hypothesized that the pattern of heavy metal accumulation could vary in the adjacent sediments of different mangrove plant species. We compared the heavy metal accumulation (As, Co, Cu, Cd, Cr, Pb, Ni, and Zn) in the mangrove sediments adjacent to Avicennia marina (AM), Bruguiera gymnorrhiza (BG), Rhizophora mucronata (RM), and Excoecaria agallocha (EA) from a mixed mangrove stand within the Indian Sundarbans. Metal concentrations (except Cr) varied significantly among the four mangrove sites. The highest concentrations of As, Cd, and Pb were observed in EA sites, Cu and Zn, in BG sites, followed by Co and Ni, in AM sites. Contamination factor, enrichment ratio, and geo-accumulation indices indicated significant Cd pollution in all the sites; however, the highest magnitudes of these indices were observed in EA sites. These indices showed very high Cu and Zn pollution in BG sites. Pollution load index and potential ecological risk index depicted overall ‘deterioration of sediment quality’ and very high risk in all the sites. Principal component analysis and cluster analysis also showed that metal accumulation was significantly different in the four sites. Overall, the results indicated that the heavy metal type and concentration in mangrove sediments could vary depending on the mangrove plant species thriving in its adjacency. However, characterizing the reasons behind such differential accumulation needs further study.

摘要

重金属在红树林植物部位的选择性积累早有报道；然而，鲜有报道与不同红树林植物物种相邻的沉积物中的不同重金属积累。我们假设不同红树林植物物种的相邻沉积物中的重金属积累模式可能不同。我们比较了与Avicennia marina (AM)、Bruguiera gemnorrhiza (BG)、Rhizophora mucronata (RM) 和Excoecaria相邻的红树林沉积物中重金属的积累（As、Co、Cu、Cd、Cr、Pb、Ni 和 Zn）阿加洛查(EA) 来自印度 Sundarbans 内的混合红树林。四个红树林地点的金属浓度（除 Cr 外）差异很大。在 EA 位点、Cu 和 Zn、BG 位点中观察到最高浓度的 As、Cd 和 Pb，其次是在 AM 位点中的 Co 和 Ni。污染因子、富集比和地积累指数表明所有站点都存在显着的 Cd 污染；然而，在 EA 站点中观察到这些指数的最高幅度。这些指标显示 BG 场地的铜和锌污染非常高。污染负荷指数和潜在生态风险指数描述了所有地点的总体“沉积物质量恶化”和非常高的风险。主成分分析和聚类分析还表明，四个位点的金属积累量存在显着差异。全面的，结果表明，红树林沉积物中的重金属类型和浓度可能因邻近红树林植物种类的不同而有所不同。然而，表征这种差异积累背后的原因需要进一步研究。