Metalaccumulating plants are known for its ability to subsist in areas that arecontaminated with heavy metals or having a naturally high level of metals insoil (Wang et al.
2003). This mechanism is called accumulation, wherein plantstolerate concentrations of heavy metals at different levels in its tissues(Baker, 2008). Kaewtubtim et al. (2016) quoted that plants can be classified asan accumulator or excluders. Potential metal accumulators translocatecontaminants from roots to aboveground parts while excluders restrictcontaminant uptake and accumulation.Mangroveforests are among the most biologically productive ecosystems worldwide, and itcompromise an important component of both coastal and marine ecosystems(Sandiyan and Kathiresan, 2012). It provides both commercial and ecologicalservices as well as a suitable habitat for myriad of aquatic species (Bruno etal.,2016).
In contrast, mangroves are exposed to heavy metal pollution due tothe manmade activities like mining, metal smelting, burning of fossil fuels andagricultural pesticide production and as well as domestic and industrial sewage(Lotfinasabasl & Gunale, 2012).Pollution,in many forms has been degrading the quality of life and among the varioustypes of pollutants, heavy metals are one of the most serious pollutants due totheir toxicity, persistence and bioaccumulation problems (MacFarlane andBurchett, 2002). Heavy metals are naturallyoccurring elements that have a high atomic weight and a density at least 5times greater than that of water (Tchounwou et al., 2014). These contaminants commonly exist inurban ecosystems, which arise primarily from industrial effluents, industrialwastes and urban run-offs (Pahalawattaarachchi et al.
, 2008). Aquatic environment polluted withheavy metals has become a worldwide problem and of scientific concern becausethe metals are indestructible and most of them have toxic effects on organisms(MacFarlane and Burchett, 2000; Oronsaye et al., 2010).
According to chemical and geological conditions,heavy metals discharged into surface waters were rapidly partitioned ontoparticulate matter and incorporated in sediments. Based on the matrixcomposition, sediments generally show a superior capacity for withholdingmetals (Salomons, 1995). The degree of heavy metals and traceelements retained in sediments is controlled by not only the dynamics ofphysical-chemical equilibration, which is governed by pH, redox conditions,oxidation states of elements, etc., but also sediment attributes such asparticle size and contents for organic matter (OM) as well as Fe/Mn hydroxides(Yu et al., 2001). Mostimportantly, the relative abundance of heavy metals in sediments is mainlydependent on the waste discharged throughseveral pathways, including atmospheric deposition, industrial activities andagricultural activities (Singh, K. et al.
, 2005; Yi et.al.,2011). Mangroveforests act as a sink for immobilizing heavy metals from anthropogenic sources(Peters et al., 1997; Tam and Wong, 1997). Due to a large proportion of fineclays, organic matter and low pH, mangrove mud effectively sequesters metals(Pahalawattaarachchi et al., 2008). Differentplants have been successfully categorized as hyperaccumulators of heavy metals,thereby, playing an important role in phytoremediation enabling for the removalof contaminants (Kumar et al.
, 1995). Mangroves have potential phytoremediationproperties because they act as pollutant eradicators (Sigua et al., 2015). The role of phytoremediation is aresource-conservative approach for remediating sites contaminated with variousheavy metals (Sigua et al.
, 2015). Furthermore, it is an effective solar-drivenand low-cost technology which utilizes native plants for metal immobilizationand extraction (Kaewtubtim et al., 2016). Accordingto Marschner (1986) also cited by Madejon et al.
, (2003), each mangrove species accumulated metals at different rates,depending on both species and plant organ as well as heavy metal concentrationand the duration of exposure (Sigua et al., 2015).Manystudies have been carried out to evaluate heavy metal accumulation in Mangrovespecies. The study conducted in Pangasihan Mangrove forest reserve in Mindanao,Philippines assessed the phytoremediation potential of mangroves. The findingsof the study showed the ability of Sonneratiaalba and Avicennia marina var. rumphiana to sequester heavy metals andact as phytoremediators. The role of mangroves in phytoremediation will preventfurther damage to coastal and marine ecosystems especially those that areexposed to urban and industrial development (Bruno et.
al., 2016). Themangrove ecosystem located at Brgy.
Binuangan, Maco, Compostela Valley Provinceis highly susceptible to the uptake of heavy metals arising from thelarge-scale and small-scale mining activities in the upland. Untreated minedrainage contributes large amounts of heavy metals going through bodies ofwater, which in turn, paves a way for an easy transport of heavy metal pollution.Currently,there is no information and recent studies conducted on the potential heavymetal accumulation of mangrove species within the mangrove forest at Brgy.
Binuangan,Maco, Compostela Valley Province. Hence this research was conducted. This researchdetermines the potential heavy metal accumulation of the two (2) most dominant mangrovespecies present in the study area.