| Title: |
Bioaccumulation of mercury in benthic communities of a river ecosystem affected by mercury mining
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| Resource Type: |
document --> technical publication --> journal article
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| Country: |
Slovenia
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| Year: |
2007 |
| Availability: |
Science of the Total Environment 377:407-415
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| Author 1/Producer: |
Suzana Žižek
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| Other Authors/Producers: |
Melena Horvat, Darija Gibicar, Vesna Fajon and Mihael J. Toman
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| Author / Producer Type: |
University research group / research institute
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| ISSN: |
ISSN: 0048-9697
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EUGRIS Keyword(s): |
Diffuse pollution-->Processes
Sediments
Water resources and their management -->Stresses, quality and ecological status
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| Short description: |
Although mercury is released by natural sources such as volcanoes, additional releases from anthropogenic sources, like coal burning and use in
products, have led to significant increases in environmental exposure and deposition. This chemical is persistent and in the environment can change
into methylmercury, its most toxic form. Mercury mining is one of the major anthropogenic sources of mercury released into the environment,
especially in rivers. Despite the fact that several mercury mining activities have ceased across Europe, river contamination by mercury is still an issue
in the mines' surroundings.
In this regard, Slovenian researchers have recently investigated the mercury cycle in the Idrijca river ecosystem, where mercury mining activities
ceased 10 years ago. To this end, they collected water, sediment, algae and insect larvae samples at four sites on the river; one located upstream
from the former mine (S1), one located at the town of Idrija, where the effluents from the mercury mine flow into the Idrijca river (S2), the third one half
way down the river stream (S3) and the last one near the confluence with the Soca river (S4). They measured the mercury content in these samples
as well as the share of mercury compounds in the methylmercury form.
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| Long description: |
Their findings were as follows:
*Total mercury concentrations in sediments and water follow the same trend. The concentration is highest in S2, but higher in S4 than in S3. In these
compartments, the share of methylmercury is small (below 2.1% of the total mercury content in water in sediments).
*The same pattern of mercury concentrations is observed in algae. However, the methylmercury content in these organisms can reach up to 8.8% of
the total mercury content.
*In insect larvae, concentration patterns vary across the seasons. The methylmercury content in macroinvertebrates is highest in autumn and summer
and can reach up to 100% of the total mercury content in these organisms.
The authors conclude that the mercury concentration in biota correlates with the concentration in water and sediments. In addition, their investigation
reveals that, regardless of the sampling site, the percentage of mercury as methylmercury increases with the food chain level (from water, algae,
macro invertebrates to fish), which indicates an active transformation, accumulation and magnification of mercury in the bottom-dwelling communities
of this heavily contaminated river.
The researchers suggest that their findings could support the fact that mercury is able to move up food chains but they highlight that further research
on this particular site would be necessary to confirm this statement.
At European Union level, mercury is a priority, as high doses can be fatal to humans, and even relatively low doses can have serious adverse impacts
on the neural development, and harmful effects on the cardiovascular, immune and reproductive systems. One of the main objectives of the
Community Strategy Concerning Mercury COM(2005)20 is to improve understanding of the mercury problem and its solutions and the findings of this
study could serve this purpose. The findings of this study highlight mercury's ability to remain in a river for long periods and the role of ecosystems as
mercury bioaccumulators in rivers.
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Submitted By:
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Professor Paul Bardos WhoDoesWhat?
Last update: 25/05/2007
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