Abstract:
This study evaluated possible groundwater contamination by leachate in areas surrounding the Payatas dumpsite through the use of toxicity tests. Groundwater samples were obtained from six deep wells of different locations around the dumpsite and subjected to heavy metal, anion, and coliform analyses. Furthermore, the samples were employed in a battery of bioassays consisting of zebrafish (96-hour subchronic toxicity test), hydra (96-hour sublethal test), lettuce (120-hour root inhibition assay), and onion (96-hour root inhibition assay). Results of the assays point to South Well 3 as a possible toxic site. On the other hand, metal analysis revealed that heavy metals were below their Minimum Detection Limits. This study suggests that a mechanism of natural attenuation by the rock profile underlying the dumpsite retains these metal contaminants, thereby slowing their advance to the water table. This may elucidate to the low toxicity levels detected in the groundwater.
