Metal naturally occurring elements that have a high

accumulating plants are known for its ability to subsist in areas that are
contaminated with heavy metals or having a naturally high level of metals in
soil (Wang et al. 2003). This mechanism is called accumulation, wherein plants
tolerate concentrations of heavy metals at different levels in its tissues
(Baker, 2008). Kaewtubtim et al. (2016) quoted that plants can be classified as
an accumulator or excluders. Potential metal accumulators translocate
contaminants from roots to aboveground parts while excluders restrict
contaminant uptake and accumulation.

forests are among the most biologically productive ecosystems worldwide, and it
compromise an important component of both coastal and marine ecosystems
(Sandiyan and Kathiresan, 2012). It provides both commercial and ecological
services as well as a suitable habitat for myriad of aquatic species (Bruno et
al.,2016). In contrast, mangroves are exposed to heavy metal pollution due to
the manmade activities like mining, metal smelting, burning of fossil fuels and
agricultural pesticide production and as well as domestic and industrial sewage
(Lotfinasabasl & Gunale, 2012).

in many forms has been degrading the quality of life and among the various
types of pollutants, heavy metals are one of the most serious pollutants due to
their toxicity, persistence and bioaccumulation problems (MacFarlane and
Burchett, 2002). Heavy metals are naturally
occurring elements that have a high atomic weight and a density at least 5
times greater than that of water (Tchounwou et al., 2014). These contaminants commonly exist in
urban ecosystems, which arise primarily from industrial effluents, industrial
wastes and urban run-offs (Pahalawattaarachchi et al., 2008).

            Aquatic environment polluted with
heavy metals has become a worldwide problem and of scientific concern because
the 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 onto
particulate matter and incorporated in sediments. Based on the matrix
composition, sediments generally show a superior capacity for withholding
metals (Salomons, 1995).

            The degree of heavy metals and trace
elements retained in sediments is controlled by not only the dynamics of
physical-chemical equilibration, which is governed by pH, redox conditions,
oxidation states of elements, etc., but also sediment attributes such as
particle size and contents for organic matter (OM) as well as Fe/Mn hydroxides
(Yu et al., 2001).

importantly, the relative abundance of heavy metals in sediments is mainly
dependent on the waste discharged through
several pathways, including atmospheric deposition, industrial activities and
agricultural activities (Singh, K. et al., 2005; Yi,

forests 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 fine
clays, organic matter and low pH, mangrove mud effectively sequesters metals
(Pahalawattaarachchi et al., 2008).

plants have been successfully categorized as hyperaccumulators of heavy metals,
thereby, playing an important role in phytoremediation enabling for the removal
of contaminants (Kumar et al., 1995). Mangroves have potential phytoremediation
properties because they act as pollutant eradicators (Sigua et al., 2015).  The role of phytoremediation is a
resource-conservative approach for remediating sites contaminated with various
heavy metals (Sigua et al., 2015). Furthermore, it is an effective solar-driven
and low-cost technology which utilizes native plants for metal immobilization
and extraction (Kaewtubtim et al., 2016).

to 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 concentration
and the duration of exposure (Sigua et al., 2015).

studies have been carried out to evaluate heavy metal accumulation in Mangrove
species. The study conducted in Pangasihan Mangrove forest reserve in Mindanao,
Philippines assessed the phytoremediation potential of mangroves. The findings
of the study showed the ability of Sonneratia
alba and Avicennia marina var. rumphiana to sequester heavy metals and
act as phytoremediators. The role of mangroves in phytoremediation will prevent
further damage to coastal and marine ecosystems especially those that are
exposed to urban and industrial development (Bruno, 2016).

mangrove ecosystem located at Brgy. Binuangan, Maco, Compostela Valley Province
is highly susceptible to the uptake of heavy metals arising from the
large-scale and small-scale mining activities in the upland. Untreated mine
drainage contributes large amounts of heavy metals going through bodies of
water, which in turn, paves a way for an easy transport of heavy metal pollution.

there is no information and recent studies conducted on the potential heavy
metal accumulation of mangrove species within the mangrove forest at Brgy. Binuangan,
Maco, Compostela Valley Province. Hence this research was conducted. This research
determines the potential heavy metal accumulation of the two (2) most dominant mangrove
species present in the study area.