| Summary: | Cilacap Oil Refinery that produces heavy metal waste containing Pb and Cu is located
across to the mangrove forests along Donan river banks. This study aimed to (1) to identify
the physical and chemical quality of the mangrove aquatic habitat and the absolute density of
mangrove vegetation, (2) to identify water quality status and to categorize the mangrove
condition based on its vegetation density, (3) to recognize the role of mangrove forest as
biofilters in controlling water pollutants of Pb and Cu that is predicted containing the
mangrove rehabilitation areas along Donan River banks, Cilacap.
The research site was grouped into four areas, which are control zone (three km before the
point source), Inner Zone (at the point source), middle zone (one km point source), and outer
zone (estuarine). Four plots were established to measure physical and chemical water quality
and mangrove tree density. Data colected were then analyzed using Pollutan index and
standard criteria of mangrove damages, regression model to identify the relationship between
mangrove tree density and Pb and Cu concentration in the water, substrate, roots, and leaves
of Rhizophora apiculata. Analysis of variance were applied among four zones to find out the
role of mangrove as biofilters for those heavy metals.
The results showed that the average of water temperature, salinity, pH, and the
concentrations of Pb and Cu pollutants in the mangrove substrates were below the allowed
water quality standards. However, the average of dissolved oxygen and the water
concentrations of Pb and Cu have exceeded the allowed water quality standards. The water
quality status was lightly-polluted, although the tree density was categorized as good
conditions and highly-dense. Even though Pb and Cu concentration in the water was not
significantly different, however, the concentrations of those heavy metals from the point
source to the estuarine zones decreased, especially the concentration of Pb in the substrat
highly reduced. Finally, the role of mangrove forest as biofilter was also recognized from the
concentration of Pb and Cu detected in the roots and leaves of Rhizophora apiculata.
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