Assessing the biodegradability of terrestrially-derived organic matter in Scottish sea loch sediments

International audience(Com. 8 juill. 2008, pourvoi n° 07-12.759, arrêt n° 806 F-P+B, D. 2008. AJ. 2140, obs. X. Delpech ; JCP E 2008. 2424, n° 11, obs. A. Salgueiro

A morphometric analysis of algal response to low dose, short-term heavy metal exposure

Three algae, Melosira granulata, Fragilaria capucina , and Anacystis cyanea , collected as part of a natural phytoplankton assemblage were found to differ in their cytological responses to low dose short-term exposure to copper and lead. In general, all were more sensitive to copper than to lead. Fragilaria was more sensitive to both metals than the other species examined. Most immediate changes in relative volume categories can be ascribed to changes in vacuole volume that are most likely the result of changes in membrane permeability. There was some degree of accommodation in all three species at 24 hours. These results are discussed in view of the natural environment of the algae, as well as in relationship to previous studies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41729/1/709_2005_Article_BF01281533.pd

A biogeochemical comparison of Sea Loch sediments: manganese and iron contents, sulphate reduction and oxygen uptake rates

The sediments of the upper basins of Lochs Goil, Fyne and Etive were high in both solid phase extractable manganese (up to 3.7% w/w), and high in pore water manganese (up to 600 mu M), while Loch Linnhe sediments were low in manganese. Solid phase manganese from the surface sediments at the deepest stations was highest in those lochs where the mean residence time of the bottom water is longest, indicating the importance of manganese cycling through the water column. Porewater iron concentrations in the top 2 cm of sediment were highest near the heads of the lochs, i.e. near the main freshwater inputs. Within sediments of Lochs Goil, Fyne and Etive high rates of total sulphate reduction were associated with high relative rates of formation of acid volatile sulphide, but this correlation did not occur in Loch Linnhe; here the formation of pyrite was more important. Loch Linnhe sulphate reduction rates were higher than those in Lochs Goil and Etive, but fixed sulphur concentrations in the sediments were lower, indicating a greater proportion of the products of sulphate reduction were being reoxidised. The sulphide burial rate was high in Loch Etive and low in Loch Linnhe. Oxygen uptake rates by sediments showed an increase near the heads of the lochs, implying the presence of a component of the terrestrial organic input which was readily degradable by marine sediment bacteria