Author(s): Royette Posadas
Email (s): firstname.lastname@example.org
Institution or organization of origin: Department of Environment and Natural Resources, Ecosystems Research and Development Bureau
The study aimed to determine the factors that affects the mercury levels and determine the similarities of the pit lake and Tagburos River (in terms of water quality) during the dry season in Sta. Lourdes, Puerto Princesa City using multivariate analysis. The first factor was correlated to pH, electrical conductivity, total dissolved solids, turbidity, and salinity which were associated to the presence of ions, particulate matter, dissolve organic matter; while the second factor was corelated to water total mercury and oxidation-reduction potential which was associated to the Hg speciation. The water physico-chemical condition of the water was used to explain the low levels of Hg in the pit lake and the river.
The sediment contains cinnabar in which Hg is in stable state and leaching of Hg was nearly impossible considering that the pH of both water sources were alkaline. Accumulation of Hg in the pit lake water may be possible over time but the interaction of Hg and dissolved organic carbon however was dominant and net increase in Hg content in the water could be insignificant. Photochemical and biogeochemical reactions transform Hg-DOC interaction labile forms such as Hg0 and organomercury forms which are volatile leaving the water with lesser Hg concentration. With the strong correlation of TDS and EC toward DOC, the Hg-DOC interaction was likely the most dominant chemical interaction in the water. Cluster analysis showed that the pit lake and the river were exclusively unique in terms of water quality.