Emissions and environmental implications of mercury from artisanal gold mining in north Sulawesi, Indonesia

doi:10.1016/S0048-9697(02)00397-2

Science of The Total Environment

Volume 302, Issues 1–3, 20 January 2003, Pages 227-236

https://doi.org/10.1016/S0048-9697(02)00397-2 Get rights and content

Abstract

In artisanal gold mining practiced in North Sulawesi Island, Indonesia, gold is separated from ore by the use of mercury, which forms an amalgam with gold. All related processes are undertaken with a low level of technical knowledge and skills, no regulation, and with disregard for the safety of human and environment health. The situation is generating serious potential health and environmental risks in the area. As part of an ongoing monitoring program, total mercury concentrations were examined in water, bottom sediment and fish samples from three main rivers in Talawaan Watershed, which receives drainage from gold mining practices. Monitoring began in May–June 2000, almost 2 years after artisanal gold mining had begun. At that time, the mercury concentration in the sediment was generally low, except in places close to the gold processing plants. In the present study, a more systematic sampling and analysis was conducted in May–June 2001. Bottom surface sediments, water, and fish samples were collected at 12 sites along the three main rivers in the watershed. In addition, one site outside the watershed was sampled to serve as a control. Sample collections were conducted in three phases in duplicate, with two-week intervals between each phase. The mercury concentration observed in this study indicated that an increase took place along the three main rivers in the watershed. Solutions to this problem must be formulated as soon as possible in order to avoid a major health, economic, and ecological disaster arising from the continuing discharge of Hg. The present study proposes that mercury dispersion occur downstream of the mining.

Introduction

Artisanal gold mining is an activity that relies mainly on manual labor and makes use of simple methods. It offers poor people an important means of livelihood and has served as a safety net in times of economic distress, especially during the extended economic crisis of Indonesia of the last five years. Approximately 10 000 workers are actively involved in artisanal mining and processing of gold deposits in the North Sulawesi Province of Indonesia. This relatively large number indicates the great importance of artisanal gold mining as an employment opportunity in this rural area.

Over 100 years ago, the Dutch complained of artisanal gold mining in the nearby Ratatotok region in the North Sulawesi Province of Indonesia, and illegal miners still operate in that region. In 1997, the awarding of a gold mine concession to the Aurora Mining Co. of Australia in the Dimembe Sub-district in the North Sulawesi Province, northeast of Manado City, gave rise to a gold rush of artisanal miners to the area and this rush has expanded to include thousands of miners.

The amalgamation method of artisanal gold mining causes mercury (Hg) emissions to leak into the environment in several different ways. For example, when Hg is unintentionally spilled onto the ground. Atmospheric transport and deposition at normal temperature is the pathway delivering Hg to many of the word's rivers, lakes and oceans. Moreover, Hg is often discharged together with other wastes into inadequate tailings ponds, or is disposed of directly into rivers and waterways. Yet another means of introducing Hg into the environment take place when purifying the amalgam by burning and vaporized Hg is released into the atmosphere.

For several decades, Hg has been recognized as an environmental pollutant (Akagi and Nishimura, 1991, Clark, 1997). The Hg pollution problem in the Talawaan Watershed has generated several potential threats to the province to date (Martens, 2000). The immediate health threat of the use of Hg for gold extraction affects those who work or live in areas around processing plants. As regards water pollution, some of the metallic Hg discharged into rivers and waterways is transformed into methyl Hg, by microorganisms then eaten by aquatic species, which are in turn consumed by humans. Like bioaccumulation of many environmental contaminants, that of Hg accumulates along the food chain of aquatic organisms (Lodenius and Malm, 1998, Veiga et al., 1999). Fish and other wildlife from various ecosystems commonly attain Hg levels of toxicological concern when directly affected by Hg emissions from human-initiated activities (Samoiloff, 1989). Solutions to these problems must be implemented as soon as possible in order to avoid a major health, economic, and ecological disaster arising from the continued discharge of Hg.

This study addresses the question of whether or not variations in Hg concentration in river systems can reflect the influence of Hg emission from gold processing plants using amalgamation. We assessed the levels of Hg concentration in water, sediment, and biological samples such as fishes in a watershed of North Sulawesi Island, Indonesia.

Section snippets

Study area

The Talawaan Watershed drains from the peak of Mount Klabat into the western coast of the peninsula of North Sulawesi (Fig. 1, Fig. 2). The highest point of this watershed is the peak of Mount Klabat (1995 m), and the total area is estimated to be 34 400 ha (Martens, 2000). The distance from the peak of Klabat to the sea is approximately 20 km. The area includes the drainage basins of the Talawaan, Kima, and Bailang Rivers. Talawaan and Bailang Rivers flow through the main center of the mining

Distribution of mercury in the river system

Hg levels among the three sampling phases in the year 2001 were variable at sampling sites T2, T3, T4, T5 (Talawaan River), B2, B3, B4 (Bailang River), and K1 (Kima River), as shown in Fig. 3 and Fig. 4. Vastly fluctuating Hg levels at one sampling site within a relative short time interval may reflect the influence of respective environmental conditions such as dilution rate, discharge, effluent mixing, and other weather-related effects. In such case, the average of a sequence observation

Conclusions

The fluctuation of Hg levels in water and sediment in relation to the sampling sites and gold processing plant locations within the Talawaan Watershed provide insight into the pathway of Hg dispersion from gold processing plants throughout the river system. Increasing Hg levels in fish samples provided strong indication of a high bioaccumulation within this contaminated area. The present study has shown that environmental contamination by Hg from artisanal gold mining activities is elevated and

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Emissions and environmental implications of mercury from artisanal gold mining in north Sulawesi, Indonesia

Abstract

Introduction

Section snippets

Study area

Distribution of mercury in the river system

Conclusions

Environ Contam Toxicol

Speciation of mercury in the environment. Toxicology

Marine Pollution. Fourth Edition

New source identification of mercury contamination in the Great Lakes

Environ Sci Technol

Monitoring of fish and human exposure to mercury due to gold mining in the Lake Victoria Goldfields, Tanzania

Sci Total Environ