Effectiveness of artificially planted mangroves on remediation of metals released from ship-breaking activities

Abstract

The pervasive and escalating issue of toxic metal pollution has gathered global attention, necessitating the exploration of innovative ecological strategies like phytoremediation. This study explored the extent of potentially toxic metal contamination status and the effectiveness of three planted mangrove species (Avicennia marina, Bruguiera gymnorhiza,and Excoecaria agallocha) in phytoremediation efforts to reduce pollution level. The results indicated that the mean concentrations of elements in the sediment of the area followed a descending sequence: Fe (27,136.67 ± 929.57 mg/kg) > Ti (3371.53 ± 228.08 mg/kg) > Sr (198.59 ± 37.43 mg/kg) > Zr (159.49 ± 22.35 mg/kg) > Rb (159.11 ± 17.63 mg/kg) > Cu (82.73 ± 5.01 mg/kg) > Zn (61.29 ± 2.42 mg/kg). The comprehensive assessment of pollution indices, encompassing enrichment factor (EF), contamination factor (CF), pollution load index (PLI), and geo-accumulation index (Igeo), elucidated a low to medium contamination level, particularly regarding Cu, primarily attributed to anthropogenic sources. Correlation analysis and principal component analysis (PCA) unveiled the influence of anthropogenic activities on heavy metal distribution. Evaluating the phytoremediation potentiality via bioconcentration factor (BCF) and translocation factor (TF) revealed limited metal accumulation in plant tissues, yet TF values exceeding 1 demonstrated efficient metal translocation from roots to aerial parts. Remarkably, Excoecaria agallocha exhibited the greatest phytoremediation potential, effectively translocating metals such as Cu and Zn to aerial parts (TF > 1). Thus, the intricate interplay between mangrove species and their environmental setting emerges as pivotal in curbing heavy metal transfer to neighboring estuarine and marine ecosystems.

Keywords: Coastal ecosystems; Heavy metal contamination; Mangrove species; Phytoremediation; Pollution indices.