Total Mercury in Soils and Sediments in the Vicinity of Abandoned Mercury Mine Area in Puerto Princesa City, Philippines

Jessie Samaniego,Rasty Rastrullo,Cris Reven Gibaga,Alexandria Tanciongco

doi:10.3390/app10134599

Abstract

The abandoned mercury (Hg) mine area in Puerto Princesa City, Palawan was included in the list of abandoned and inactive mines in the Philippines which pose a high risk to human health and the environment, and require rehabilitation. The mine site, operated by Palawan Quicksilver Mines, Inc. (PQMI) from 1953 to 1976, is located approximately 3 km inland from Honda Bay coast and within the catchment of the Tagburos River, which is a local fishery and recreational area. In this study, total Hg levels in soils and sediments were measured to assess the possible release of Hg from the site into the surrounding natural environment. Results showed that total Hg (THg) concentrations found in soils (0.04–67.5 mg kg−1), mine waste calcines (52.7–924.2 mg kg−1), river sediments (1.8–119 mg kg−1), and marine sediments (0.04–12.7 mg kg−1) were elevated compared to the global background of 0.045–0.16 mg kg−1. The high concentrations of Hg in soils and river sediments were influenced by the different pathways for the release of Hg from its mine operations; while Hg in marine sediments was caused by the erosion of mine waste calcines near the pit lake, and calcines used to construct a wharf at the nearby Honda Bay. Mine wastes represent the largest source of Hg contamination in the area, due to the low efficiency of the recovery process during calcination. This work corresponds with the Minamata Convention on Mercury on the updated environmental assessments of abandoned Hg mines as potential source sites of mercury contamination.

Highlights

Mining has been an important economic activity in the Philippines, which started centuries ago.With a lack of environmental regulations until recent times, old mining operations have led to many abandoned mine sites, and resulted in high heavy metal concentrations in soils and sediments in the vicinity
Most of the mercury mining areas around the world have been investigated in relation to their Hg pollution in their local ecosystems, which pose potential risks to humans living nearby
Similar patterns of high to extremely high (46,000 mg kg−1 ) Hg concentrations in mine waste calcines and runoff sediments were reported from these Hg mining sites, which pose potential contamination on soil, water, and air in the area [7]

Summary

Introduction

Mining has been an important economic activity in the Philippines, which started centuries ago.With a lack of environmental regulations until recent times, old mining operations have led to many abandoned mine sites, and resulted in high heavy metal concentrations in soils and sediments in the vicinity. In the Philippines, there are more than 20 mine sites that are classified as inactive and abandoned, one of which is the Palawan Quicksilver Mines, Inc. Princesa City, Palawan [1] This former mine site is considered as one of the Hg waste hot spots of the world, because the Hg pollution is affecting the marine environment and the people living nearby [2]. Most of the mercury mining areas around the world have been investigated in relation to their Hg pollution in their local ecosystems, which pose potential risks to humans living nearby. Similar patterns of high to extremely high (46,000 mg kg−1 ) Hg concentrations in mine waste calcines and runoff sediments were reported from these Hg mining sites, which pose potential contamination on soil, water, and air in the area [7]

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Results