Phytoremediation of Pb in the sediment of a mangrove ecosystem

PURPOSE: Coal-fuelled power plants can discharge hazardous materials, particularly heavy metals such as lead (Pb). An alternative way of reducing Pb concentration from contaminated sediments is through phytoremediation. Presently, there are few research findings on the phytoremediation potential of mangroves on metals like Pb. The study was conducted to survey and identify mangroves that thrive near the coal-fired power plant and to assess the phytoremediation potential of mangroves on Pb in sediment. MATERIALS AND METHODS: The study sites were located in the mangrove ecosystems of Sitio Oyon and Sitio Asinan in Masinloc, Zambales, Philippines. The first stage of our study was to survey and identify the mangrove species. The second stage was to assess the levels of Pb in the sediments, water, and tissues of mangrove trees. The diversity assessment of the mangrove species was done through the use of 10 × 12 m quadrat technique. Water and sediment samples from each mangrove ecosystem were collected using composite sampling methods. RESULTS AND DISCUSSION: Three mangrove species were identified in the study sites: Avicennia marina, Rhizophora stylosa, and Sonneratia alba. The order of importance of the mangrove trees in the two sampling locations, based on an importance value index (IVI), were as follows: SA (IVI = 171.20) > AM (77.79) > RS (51.01). The total uptake of Pb from sediments near the power plants varied significantly (p ≤ 0.001) among the three mangrove species. S. alba had the highest Pb uptake of 48.4 kg ha⁻¹ followed by A. marina (23.1 kg ha⁻¹), and R. stylosa (2.4 kg ha⁻¹). These three mangrove species have the potential to phytoremediate Pb in the sediment. CONCLUSIONS: The three mangrove species present in the coastal ecosystem near the electric power plant—A. marina, R. stylosa, and S. alba—were potential phytoremediators of sediment Pb. The present study indicated that the mangroves possess beneficial characteristics that remove Pb from contaminated sediments in areas directly affected by coal-fired power plants, and thus have potential phytoremediation properties.