Avicennia marina (Forssk.) Vierh. as phytoaccumulator of sediment heavy metals in the Las Piñas – Parañaque Critical Habitat and Ecotourism Area (Philippines).

Abstract

Las Piñas-Parañaque Critical Habitat and Ecotourism Area (LPPCHEA), being the last coastal frontier of Metro Manila, functions as a sink to a variety of pollutants including heavy metals. Its mangrove forest is known to accumulate heavy metals but such uptake is not conclusive of its capacity to alleviate environmental pollution. One of the methods used to verify such capacity of mangroves is to assess their Bioconcentration Factor (BCF) values which compare environmental and plant tissue concentrations of heavy metals. BCF values greater than one (>1) indicates efficiency of an organism to phytoaccumulate (Usman, 2013; EPA, 2007). Hence, in order to determine the phytoaccumulation efficiency of the mangrove forest in LPPCHEA, the research studied the BCF values of the dominant species, Avicennia marina, in the Long Island of LPPCHEA – one of the two islands in the area, and is situated in the middle of Manila Bay and Cavitex. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP/OES) was used to detect and determine the Cr, Cu, and Pb concentrations of the ten composite samples of sediments, barks of stems, and pneumatophores in the area. It was found that Cu (37.41 ppm) had the highest concentration in the plant, followed by Pb (15.37 ppm) then Cr (4.94 ppm). However, taking into account the BCF values of the heavy metals, it was found that Pb (1.0913) was the highest phytoaccumulated heavy metal, followed by Cu (0.4403) then Cr (0.2806). The study suggests that A. marina is efficient in phytoaccumulating Pb in LPPCHEA. Furthermore, the root and bark tissues of the mangrove contribute equally to its phytoaccumulating capacity.