Submitted to: Journal of Soils and Sediments
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/6/2013
Publication Date: 8/5/2013
Citation: Paz-Alberto, A.M., Celestino, A.B., Sigua, G.C. 2013. Phytoremediation of Pb in the sediment of a mangrove ecosystem. Journal of Soils and Sediments. 14(1):251-258. Interpretive Summary: The world is facing great risks because of heavy emissions from industries that include coal and ore mining activities, mineral smelting, production of chemical-related products such as fertilizers, pesticides, batteries and paints, manufacture of machineries and building coal powered electricity plants. Significant waste products that are emitted are heavy metals. Increase accumulation of heavy metals from the normal level in the substrates would result to detrimental impacts on human health as well as the environment. There is an emerging green technology that uses plants for the removal or degradation of harmful organic pollutants and toxic metals from the soil, sediment and water which is called phytoremediation. Mangroves are salt tolerant that are found mostly in the intertidal areas of tropical and subtropical shorelines and in marshy ecosystem have potential phytoremediation properties. The three mangrove species, Avicennia marina, Rhizophora stylosa and Sonneratia alba, present in the coastal ecosystem near the electric power plant were potential phytoremediators of sediment lead (Pb). Mangroves have many traditional uses and ecological services, but their ability to assimilate excess Pb from soil substrate is still unknown. The objectives of the study were 1) to identify mangroves that thrive near a coal-fired power plant, and 2) to assess phytoremediation potentials of mangroves for Pb in the sediments. Results indicated that mangroves possessed many beneficial characteristics to remove Pb from contaminated sediments in areas directly affected by coal-powered electric plants. The total uptake of Pb from sediments near the power plants varied significantly among the three mangrove specie. Sonneratia alba had the highest Pb uptake followed by Avicennia marina and Rhizophora stylosa. These three mangrove species have the potentials to phytoremediate Pb in soils and sediment. Our results suggest that it would be beneficial to plant more mangrove trees in coastal sites with Pb contamination.
Technical Abstract: Lead (Pb) is a naturally occurring element that poses environmental risks and hazards if present at elevated concentration. It is being released into the environment because of industrial uses, combustion of fossils fuels and from coal-fired power plants. Coal-fired power plants can discharge hazardous materials particularly heavy metals, especially Pb in the waste stream of the plant that possibly leads to contamination in the neighboring population and surroundings. An alternative way of reducing Pb concentration from the sediments or soils is through phytoremediation. Phytoremediation is an emerging green technology that uses plants for the removal or degradation of harmful organic pollutants and toxic metals from the soils, sediments, and water. Presently, there are few research findings that plants such as mangroves thriving in marshy ecosystem have the phytoremediation potential. Mangroves are salt tolerant that are found mostly in the intertidal areas of tropical and subtropical shorelines. The study was conducted to determine the phytoremediation potential of mangroves for sediment Pb associated with coal-fired power plant. A total of three mangrove species: Avicennia marina (AM); Rhizophora stylosa (RS); and Sonneratia alba (SA) were identified in the study sites. The order of occurrence for mangrove trees in 120 square meters quadrat were SA (59) > AM (44) > RS (14). The total uptake of Pb from sediments near the power plants varied significantly (p=0.001) among the three mangrove specie. Sonneratia alba had the highest Pb uptake of 48.4 kilogram per hectare (kg/ha) followed by Avicennia marina (23.1 kg/ha) and Rhizophora stylosa (2.4 kg/ha). These three mangrove species have the potentials to phytoremediate Pb in soils and sediment.