Assessment of Trace Elements in Soils and Sediments in the Abandoned Mercury Mine Site in Puerto Princesa City, Philippines

Abstract

An abandoned mercury mine area in Puerto Princesa City, which was previously operated by Palawan Quicksilver Mines, Inc. (PQMI) from 1953 to 1976, is known for its unrehabilitated open-pit of mercury-rich rocks and exposed mine waste calcine stockpiles in the vicinity. In order to establish an understanding on the geology of the abandoned mercury mine deposit and to obtain clues in determining the possible metal pollutants in the area, measurement of trace element concentrations of soil and sediments collected from the PQMI vicinity were conducted. Soil and sediment samples were analyzed for heavy metals, rare-earth elements and naturally occurring radioactive elements and determined its contamination factor as part of risk assessment. Analytical results showed that aside from mercury, several heavy metals (nickel, chromium, manganese) were found to be anomalous due to the geology of the area. Statistical analyses show that chromium, nickel and antimony present the highest contamination factor among the sampling groups. Mercury is found to have negative bias with higher rare earth elements concentration but positively correlated with arsenic, antimony, and thallium. In general, there is low concentration of rare earth elements (except for scandium) in comparison with its respective average crustal concentration. Due to the nature of geology in the area, naturally occurring radioactive elements influence is also minimal. The results of this study, especially on the assessment of soil and sediment pollutants, are recommended as guidance to its mine rehabilitation.

Integrating Historic Mine Hazard Scoring for Comprehensive Assessment of Abandoned Mine Rehabilitation in the Philippines

“…Sediments, soil and rock samples were collected from both areas and then subjected to geochemical analyses. The main contributor for the hazard score came from the elements with highest contamination factor, mercury, chromium, nickel and antimony [3], which were likewise found in elevated values. For solid sources, air and direct contact pathways were considered.…”

“…To further aid the prioritization of rehabilitation of the various abandoned mines throughout the country, this paper proposes an integrated methodology incorporating an abandoned mine scoring system that could be adapted for this purpose. [3], [10]- [12], and its location is marked in Fig. 1.…”

“…Each pathway (groundwater, surface water, air, direct contact) and the corresponding receptors per source were accounted for physico-chemical characteristics found on-site. All these properties were summarized to calculate for the environmental hazard score (ESc) as shown in (3), where AV is the average value for each element, RT is the relevant toxicity, which encompasses toxicity in human, environment, and biota due to one or more factors: ingestion, inhalation, liquid wastes and livestock, and Q is the total score for the receptor of hazard. Similarly, the factor 10000 was used to reduce the magnitude of scores.…”

“…At each mine feature, pollution sources were identified and then considered for potential pathways and receptors, as described in Table 6. References for the laboratory results used for this study were from the same authors ( [23] for water analyses; [3] for sediment analyses), which were used as input for the scoring. The liquid accumulation (lakewater) at the abandoned open pit area (Mine Pit) was considered as a liquid source.…”

Modelling the Origin, Fate, and Ecological and Health Impacts of Heavy Metals from an Abandoned Mercury Mine in a Paradise Island in the Philippines

“…The villages are home to more than 12,200 people in 2015. The open pit-mining of cinnabar for Hg from 1953 to 1976 resulted to an artificial lake known as PQMI pit lake [10,16]. The lake is traversed to the south by the Tagburos River that drains to Honda Bay.…”