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Arsenic speciation and water pollution associated with mining in the Coeur d'Alene Mining District, Idaho. Research technical completion report, G903-06 Item Info

The Coeur d' Alene Mining District is one of the major silver, lead, and zinc producing areas in the United States. The area also encompasses some of the foremost pollution problems in Idaho. The primary problems of environmental concern in this area today are the operating and abandoned tailings piles scattered throughout the district, the huge quantities of mine wastes accumulated along the streams, and the acid mine drainage from existing mines in the district. From previous studies, it is known that mine wastes containing iron sulfide (pyrite) in this area are capable of producing acid waters under oxidizing conditions. The redox status of ground water is an important factor in determining the degree of acid water formation and subsequent leaching of metals from mine tailings and ore bodies in this mining area. A new approach for measurement of the redox status of ground water involving analysis of water samples for concentrations of two arsenic species, As(V) and As(III), has been studied in this project. Based on thermodynamic equilibrium considerations, the apparent redox conditions can be evaluated from measured ratios of As(V)/As(III) in water. A simple solvent extraction method has been developed for the separation of arsenic species in mine waters using ammonium pyrrolidinedthiocarbamate (APDTC) as a chelatinq agent. The APDTC extraction method combined with neutron activation technique provides a very sensitive method for determining arsenic species in natural water systems. A detection limit of 0.1 ppb for the arsenic species in natural waters can be easily achieved using this method. This analytical method for arsenic speciation study is in the process of being published by ANALYTICAL CHEMISTRY. Ground water samples were collected from a major lead-zinc mine (the Bunker Hill Mine) and from other locations of the Coeur d'Alene Mininq District to study the relationships between the arsenic species and other water quality data. The As(V)/As(III) ratios in ground waters collected from the Bunker Hill Mine were found to vary by more than two orders of magnitude indicating a wide range of redox conditions existing in the mine. The quality of ground water in the mine is strongly correlated with the ratio of As(V)/As(III) found in the system. Good quality waters were generally associated with low ratios (<1) of As(V)/As(III). The ratio of the arsenic species and the concentrations of dissolved metals in the mine waters varied considerably with time. During the spring run-off, very high As(V)/As(III) ratios were observed in some poor quality waters presumably due to leaching of oxidized ores and mine wastes in certain locations of the upper levels of the mine. In the late summer, the ratio of As(V)/As(III) decreased as the system became more anaerobic and the water quality showed significant improvement correspondingly. The distribution of the arsenic species appears to be a useful chemical indicator to evaluate the potential of acid water formation and associated metal pollution problems in the ground water systems of this and other similar mining areas.

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Title:
Arsenic speciation and water pollution associated with mining in the Coeur d'Alene Mining District, Idaho. Research technical completion report, G903-06
Authors:
Wai, C. M.; Mok, W. M.
Date Created (ISO Standard):
1985-10
Description:
The Coeur d' Alene Mining District is one of the major silver, lead, and zinc producing areas in the United States. The area also encompasses some of the foremost pollution problems in Idaho. The primary problems of environmental concern in this area today are the operating and abandoned tailings piles scattered throughout the district, the huge quantities of mine wastes accumulated along the streams, and the acid mine drainage from existing mines in the district. From previous studies, it is known that mine wastes containing iron sulfide (pyrite) in this area are capable of producing acid waters under oxidizing conditions. The redox status of ground water is an important factor in determining the degree of acid water formation and subsequent leaching of metals from mine tailings and ore bodies in this mining area. A new approach for measurement of the redox status of ground water involving analysis of water samples for concentrations of two arsenic species, As(V) and As(III), has been studied in this project. Based on thermodynamic equilibrium considerations, the apparent redox conditions can be evaluated from measured ratios of As(V)/As(III) in water. A simple solvent extraction method has been developed for the separation of arsenic species in mine waters using ammonium pyrrolidinedthiocarbamate (APDTC) as a chelatinq agent. The APDTC extraction method combined with neutron activation technique provides a very sensitive method for determining arsenic species in natural water systems. A detection limit of 0.1 ppb for the arsenic species in natural waters can be easily achieved using this method. This analytical method for arsenic speciation study is in the process of being published by ANALYTICAL CHEMISTRY. Ground water samples were collected from a major lead-zinc mine (the Bunker Hill Mine) and from other locations of the Coeur d'Alene Mininq District to study the relationships between the arsenic species and other water quality data. The As(V)/As(III) ratios in ground waters collected from the Bunker Hill Mine were found to vary by more than two orders of magnitude indicating a wide range of redox conditions existing in the mine. The quality of ground water in the mine is strongly correlated with the ratio of As(V)/As(III) found in the system. Good quality waters were generally associated with low ratios (<1) of As(V)/As(III). The ratio of the arsenic species and the concentrations of dissolved metals in the mine waters varied considerably with time. During the spring run-off, very high As(V)/As(III) ratios were observed in some poor quality waters presumably due to leaching of oxidized ores and mine wastes in certain locations of the upper levels of the mine. In the late summer, the ratio of As(V)/As(III) decreased as the system became more anaerobic and the water quality showed significant improvement correspondingly. The distribution of the arsenic species appears to be a useful chemical indicator to evaluate the potential of acid water formation and associated metal pollution problems in the ground water systems of this and other similar mining areas.
Subjects:
mine wastes water pollution arsenic speciation groundwater pollution
Location:
Coeur d'Alene River
Latitude:
47.52
Longitude:
-116.53
Collection:
Coeur d'Alene Basin
Series:
Water for Idaho
IWRRI number:
198512
Rights:
Rights to the digital resource are held by the University of Idaho. http://www.uidaho.edu/
Publisher:
University of Idaho
Contributing Institution:
University of Idaho
Type:
Text
Format:
application/pdf
Cataloger:
wbv
Date Digitized:
2012

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Preferred Citation:
"Arsenic speciation and water pollution associated with mining in the Coeur d'Alene Mining District, Idaho. Research technical completion report, G903-06", Idaho Waters Digital Library, University of Idaho Library Digital Collections, https://www.lib.uidaho.edu/digital/iwdl/items/iwdl-cda_wai_1985.html
Rights
Rights:
Rights to the digital resource are held by the University of Idaho. http://www.uidaho.edu/
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