Title

Assessment of the Retention and Resorption of Heavy Metals in the Mangrove Species Avicennia marina (Forsk.) Contaminated with Mining EFFLUENTS

Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science in Environmental Science

Department

Environmental Science

First Advisor

Severino G. Salmo III, PhD

Abstract

This study assessed the retention and resorption of heavy metals (HMs; Ni, Cr, and Cu) in the sediments and plant tissues (from roots, branches, and leaves) of Avicennia marina among different growth stages (as trees, seedlings and saplings) and with distance (as near vs. far) from source of mining effluents. The retention and resorption of HMs were evaluated through Biological Concentration Factor (BCF; the ratio of HM concentrations between roots and sediments), Translocation Factor (TF; the ratio of HM concentrations between leaves and roots), and Biological Accumulation Coefficient (BAC; the ratio of HM concentrations between leaves and sediments). Results showed that HMs in near mining (NM) sites were at least two folds higher than the far mining (FM) sites and were correlated to the vegetation and sediment characteristics. The HM accumulation was comparable among different growth stages for Ni and Cu but not for Cr. However, the translocation of HMs in different plant tissues differed among growth stages. The HMs were retained mainly in roots, branches, and leaves with mean BACs of 0.02, 0.62, and 0.02 for Ni, Cu, and Cr, respectively. In the leaves, the HM concentrations changed with leaf age from fresh to senescent leaves. The HMs in litter materials are potentially reintroduced in the sediments, and are then reabsorbed by the plant. The results suggest that the HM retention and resorption mechanisms used by A. marina are effective adaptation strategy to survive in a mining-contaminated sediment.

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