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Temporal and spatial distribution of waterborne mercury in a gold miner's river

Picado, Francisco LU and Bengtsson, Göran LU (2012) In Journal of Environmental Monitoring 14(10). p.2746-2754
Abstract
We examined the spatial and temporal (hourly) variation of aqueous concentrations of mercury in a gold miner's river to determine factors that control transport, retention, and export of mercury. The mercury flux was estimated to account for episodic inputs of mercury through mining tailings, variations in flow rate, and the partitioning of mercury between dissolved and particulate phases. Water samples were collected upstream and downstream of two gold mining sites in the Artiguas river, Nicaragua. The samples were analyzed for dissolved and suspended mercury, total solids, dissolved organic carbon, and total iron in water. Water velocity was also measured at the sampling sites. We found that mercury was mainly transported in a suspended... (More)
We examined the spatial and temporal (hourly) variation of aqueous concentrations of mercury in a gold miner's river to determine factors that control transport, retention, and export of mercury. The mercury flux was estimated to account for episodic inputs of mercury through mining tailings, variations in flow rate, and the partitioning of mercury between dissolved and particulate phases. Water samples were collected upstream and downstream of two gold mining sites in the Artiguas river, Nicaragua. The samples were analyzed for dissolved and suspended mercury, total solids, dissolved organic carbon, and total iron in water. Water velocity was also measured at the sampling sites. We found that mercury was mainly transported in a suspended phase, with a temporal pattern of diurnal peaks corresponding to the amalgamation schedules at the mining plants. The concentrations decreased with distance from the mining sites, suggesting dilution by tributaries or sedimentation of particle-bound mercury. The lowest total mercury concentrations in the water were less than 0.1 mu g l(-1) and the highest concentration was 5.0 mu g l(-1). The mercury concentrations are below the present WHO guidelines of 6 mu g l(-1) but are considered to lead to a higher risk to aquatic bacteria and fish in the stream than to humans. The aqueous concentrations exceed the hazard endpoints for both groups by a probability of about 1%. Particulate mercury accounted for the largest variation of mercury fluxes, whereas dissolved mercury made up most of the long-range transport along the stream. The estimated total mass of mercury retained due to sedimentation of suspended solids was 2.7 kg per year, and the total mass exported downstream from the mining area was 1.6 kg per year. This study demonstrates the importance of the temporal and spatial resolution of observations in describing the occurrence and fate of mercury in a river affected by anthropogenic activities. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Environmental Monitoring
volume
14
issue
10
pages
2746 - 2754
publisher
Royal Society of Chemistry
external identifiers
  • wos:000309189200023
  • scopus:84867019177
ISSN
1464-0325
DOI
10.1039/c2em30203a
language
English
LU publication?
yes
id
1538c0bc-e9bd-4c6b-a426-7385e2962826 (old id 3190033)
date added to LUP
2012-12-04 14:01:47
date last changed
2017-07-23 03:03:54
@article{1538c0bc-e9bd-4c6b-a426-7385e2962826,
  abstract     = {We examined the spatial and temporal (hourly) variation of aqueous concentrations of mercury in a gold miner's river to determine factors that control transport, retention, and export of mercury. The mercury flux was estimated to account for episodic inputs of mercury through mining tailings, variations in flow rate, and the partitioning of mercury between dissolved and particulate phases. Water samples were collected upstream and downstream of two gold mining sites in the Artiguas river, Nicaragua. The samples were analyzed for dissolved and suspended mercury, total solids, dissolved organic carbon, and total iron in water. Water velocity was also measured at the sampling sites. We found that mercury was mainly transported in a suspended phase, with a temporal pattern of diurnal peaks corresponding to the amalgamation schedules at the mining plants. The concentrations decreased with distance from the mining sites, suggesting dilution by tributaries or sedimentation of particle-bound mercury. The lowest total mercury concentrations in the water were less than 0.1 mu g l(-1) and the highest concentration was 5.0 mu g l(-1). The mercury concentrations are below the present WHO guidelines of 6 mu g l(-1) but are considered to lead to a higher risk to aquatic bacteria and fish in the stream than to humans. The aqueous concentrations exceed the hazard endpoints for both groups by a probability of about 1%. Particulate mercury accounted for the largest variation of mercury fluxes, whereas dissolved mercury made up most of the long-range transport along the stream. The estimated total mass of mercury retained due to sedimentation of suspended solids was 2.7 kg per year, and the total mass exported downstream from the mining area was 1.6 kg per year. This study demonstrates the importance of the temporal and spatial resolution of observations in describing the occurrence and fate of mercury in a river affected by anthropogenic activities.},
  author       = {Picado, Francisco and Bengtsson, Göran},
  issn         = {1464-0325},
  language     = {eng},
  number       = {10},
  pages        = {2746--2754},
  publisher    = {Royal Society of Chemistry},
  series       = {Journal of Environmental Monitoring},
  title        = {Temporal and spatial distribution of waterborne mercury in a gold miner's river},
  url          = {http://dx.doi.org/10.1039/c2em30203a},
  volume       = {14},
  year         = {2012},
}