Accumulation and partitioning of heavy metals in mangroves: A synthesis of field-based studies

• Published in: Chemosphere (Oxford) Vol. 69; no. 9; pp. 1454 - 1464
• Main Authors: MacFarlane, Geoff R., Koller, Claudia E., Blomberg, Simon P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2007; Elsevier
• Subjects: Animal, plant and microbial ecology; Applied ecology; Bioaccumulation; bioconcentration factors; Biodegradation of pollutants; Biodegradation, Environmental; Biological and medical sciences; Biotechnology; Brackish; Copper; Ecotoxicology, biological effects of pollution; Environment and pollution; Fundamental and applied biological sciences. Psychology; Heavy metals; Industrial applications and implications. Economical aspects; Lead; leaves; Mangrove; mangroves; Marine and brackish environment; Metals, Heavy - analysis; Plant Leaves - growth & development; Plant Roots - growth & development; Rhizophoraceae; Rhizophoraceae - growth & development; roots; sediment contamination; translocation (plant physiology); Verbenaceae; Water Pollutants, Chemical - analysis; Wetlands; Zinc; Lead; Copper; Bioaccumulation; Mangrove; Heavy metals; Zinc; Brackish water environment; Pollutant behavior; Heavy metal; Phytoremediation; Aquatic environment; Partitioning; Ecological recovery; Phase partition; Biological accumulation; Field study
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.04.059

We report the findings of a comparative analysis examining patterns of accumulation and partitioning of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) in mangroves from available field-based studies to date, employing both species level analyses and a phylogenetic approach. Despite mangroves being a taxonomically diverse group, metal accumulation and partitioning for all metals examined were broadly similar across genera and families. Patterns of metal accumulation were also similar regardless of whether species were classified as salt secreting or non-secreting. Metals were accumulated in roots to concentrations similar to those of adjacent sediments with root bio-concentration factors (BCF; ratio of root metal to sediment metal concentration) of ⩽1. Root BCFs were constant across the exposure range for all metals. Metal concentrations in leaves were half that of roots or lower. Essential metals (Cu and Zn; translocation factors (TF; ratio of leaf metal to root metal concentration) of 0.52 and 0.53, and leaf BCFs of 0.47 and 0.51, respectively) showed greater mobility than non-essential metals (Pb; TF of 0.31 and leaf BCF of 0.11). Leaf BCFs for the essential metals Cu and Zn decreased as environmental concentrations increased. The non-essential metal Pb was excluded from leaf tissue regardless of environmental concentrations. Thus mangroves as a group tend to operate as excluder species for non-essential metals and regulators of essential metals. For phytoremediation initiatives, mangrove ecosystems are perhaps best employed as phytostabilisers, potentially aiding in the retention of toxic metals and thereby reducing transport to adjacent estuarine and marine systems.