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Increased Dissolved Organic Carbon (DOC) in Central European Streams is Driven by Reductions in Ionic Strength Rather than Climate Change or Decreasing Acidity

Authors :
Pavel Krám
Filip Oulehle
William H. McDowell
J. Hruška
Source :
Environmental Science & Technology. 43:4320-4326
Publication Year :
2009
Publisher :
American Chemical Society (ACS), 2009.

Abstract

Temporal trends in DOC concentration and flux were investigated at two geochemically distinct forested catchments in western Czech Republic. Mean discharge-weighted DOC concentrations averaged 18.8 mg L(-1) at the acidic Lysina catchment, and 20.2 mg L(-1) at base-rich and well-buffered Pluhuv Bor. Between 1993 and 2007 DOC in streamwater increased significantly in both catchments: the mean annual increase was 0.42 mg L(-1) yr(-1) (p < 0.001) at Lysina and 0.43 mg L(-1) yr(-1) (p < 0.001) at Pluhuv Bor, resulting in cumulative increases of 64 and 65%, respectively. These long-term increases in streamwater DOC were correlated with only modest increases in stream pH in both catchments, but large declines in ionic strength (IS), that resulted from declining atmospheric deposition. Neither catchment has undergone changes in soil-water pH, yet DOC concentrations tripled in the soil-water of both catchments. We conclude that changes in ionic strength of soil-water and streamwater, rather than acidity, are the primary drivers of changes in streamwater DOC in this region. Temperature, precipitation and discharge show no statistically significant trends during the study period, suggesting that climate change has played no role in the changes in DOC that we have observed.

Details

ISSN :
15205851 and 0013936X
Volume :
43
Database :
OpenAIRE
Journal :
Environmental Science & Technology
Accession number :
edsair.doi.dedup.....d3bc7814060a8677e46f3cb6eb1c2e9d
Full Text :
https://doi.org/10.1021/es803645w