Difference between revisions of "Heavy metal content of mussels in the Western Scheldt estuary"
| Line 9: | Line 9: | ||
<u>'''Main results of the study'''</u> | <u>'''Main results of the study'''</u> | ||
| − | Heavy metal concentrations showed both in the Western Scheldt estuary as in the Eastern Scheldt bay a decreasing trend towards the sea. | + | Surprisingly, for most metals, concentrations in mussels the Eastern Scheldt bay were equally high as those in the Western Scheldt estuary. Concentrations were (in µg metal/ g mussel): arsenicum: 7 - 20 µg/g, cobalt: 0.8 - 2.2 µg/g, copper: 5 - 22 µg/g, manganese: 5 - 20 µg/g, lead: 2 - 6.1 µg/g, cadmium 1 - 1.8, chrome: 1 - 2 µg/g, iron: 70 - 200 µg/g, nickel: 0.5 - 5 µg/g, zinc: 50 - 150 µg/g. Heavy metal concentrations in mussels showed both in the Western Scheldt estuary as in the Eastern Scheldt bay a decreasing trend towards the sea. |
| + | |||
| + | The relatively low (compared to the Eastern Scheldt) concentrations in the Western Scheldt might be related to recent Belgian measures to improve the water quality. The high concentrations in the Eastern Scheldt are unexpected since water pollution has been drastically reduced. Presumably metals stored in the soil became again available for uptake by mussels. Changing conditions can cause soil particles and associated metals to resuspend, and be taken up by mussels. | ||
Revision as of 10:35, 14 July 2009
Context of the study
Since 1987, the Eastern Scheldt estuary was blocked by dams (the DeltaWorks project) to create a barrier against flooding. Because of this blockade the Eastern Scheldt was turned from an estuary to a protected marine bay. Input of chemical contaminants from land decreased drastically, although heavy metals might still persist in the soils. The adjacent Western Scheldt drains through the most populated and industrial regions of Belgium, The Netherlands and France, making it one most polluted rivers of Europe and one of the major sources of heavy metals in the North Sea.
Content of the study
The study aims to compare the heavy metal contents of mussels in the Eastern Scheldt bay with those in the Western Scheldt estuary. This way they can asses whether heavy metal levels indeed have gone down in the Eastern Scheldt. The mussels were sampled in a land to sea gradient, which in the Western Scheldt coincided with a gradient of salinity and pollution.
Main results of the study
Surprisingly, for most metals, concentrations in mussels the Eastern Scheldt bay were equally high as those in the Western Scheldt estuary. Concentrations were (in µg metal/ g mussel): arsenicum: 7 - 20 µg/g, cobalt: 0.8 - 2.2 µg/g, copper: 5 - 22 µg/g, manganese: 5 - 20 µg/g, lead: 2 - 6.1 µg/g, cadmium 1 - 1.8, chrome: 1 - 2 µg/g, iron: 70 - 200 µg/g, nickel: 0.5 - 5 µg/g, zinc: 50 - 150 µg/g. Heavy metal concentrations in mussels showed both in the Western Scheldt estuary as in the Eastern Scheldt bay a decreasing trend towards the sea.
The relatively low (compared to the Eastern Scheldt) concentrations in the Western Scheldt might be related to recent Belgian measures to improve the water quality. The high concentrations in the Eastern Scheldt are unexpected since water pollution has been drastically reduced. Presumably metals stored in the soil became again available for uptake by mussels. Changing conditions can cause soil particles and associated metals to resuspend, and be taken up by mussels.
