Risk Assessment of Mercury in Soil and Surface Water in Brgy. Santa Lourdes, Puerto Princesa City, Palawan

Abstract

Abstract Mercury sources influence human health, especially in urban areas with high population density and intensive anthropogenic activities. Barangay Sta. Lourdes, Puerto Princesa, Palawan in South-Eastern Philippines, was one of the mercury hotspots with cinnabar as a primary mineral. The mines had to close because of economic downtrends during the 1970s. Several samples were taken from the area, and concentration distribution was determined to identify potential hazard exposure. Doses contacted through ingestion, inhalation, and dermal absorption were calculated using US EPA exposure parameters. The soil was found to be enriched in Hg with the highest Total Hg (THg) recorded at 977.70 ppm. The correlation of soil pH and Hg shows a 0.64 decrease in THg for every unit increase in pH. High THg was noted during the rainy season and tended to erode mercury-laden soil into the river. The highest risk is associated with ingestion and dermal absorption, with negligible risk through air inhalation. The samples near the abandoned quicksilver mines recorded the highest THg concentrations with a hazard index (HI) greater than 1, signifying possible adverse health risks for the nearby residents. Mercury soil contamination maps indicated sources of the contamination, which can help future studies for remediation.