0 1995, by the American Society of Limnology and Oceanography, Inc. Acidification signals in estuarine sediment cores

• Main Author: Per Kristian Egeberg
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Norway; Atlantic salmon
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.570.5400; http://www.aslo.org/lo/toc/vol_40/issue_8/1438.pdf

The hypothesis that estuarine sediment cores contain signals which can be used to reconstruct shifts in the concentration of riverine humic matter (HM) and dissolved aluminum (Al) during acidification is ex-amined. Dated sediment cores from Topdal Fjord (southern Norway) were analyzed for humic matter and alkaline extractable Al. The proportions of riverine and marine HM were estimated from carbon-to-nitrogen ratios (C: N). The results agree qualitatively and quantitatively with predictions based on Al and HM behavior in estuaries and the suspected effect of acidification on the concentmtion of these parameters. The doubling in the concentration of riverine Al and 50 % reduction in riverine HM in sediment cores from the Topdal estuary coincide with an abrupt increase in the proportion of Topdal River discharge originating from areas in which the critical loads of acidity have been exceeded by sulfur deposition. HM started to decrease and Al started to increase concurrently with declining catches of Atlantic salmon around A.D. 1900. The concentrations of Al and humic matter (HM) can affect the survival of fish (Driscoll et al. 1980) and in turn these concentrations are affected by acidification. Acid-ification has damaged freshwater ecosystems in southern