Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolved organic carbon solubility. To further investigate the relationship between deposition chemistry and dissolved organic carbon export in peatlands, a field experiment was conducted to compare the pore water chemistry and peat microbial enzyme activity of mesocosms receiving sulfate amendments to mesocosms receiving no additions. To consider how peatlands respond during recovery from increased inputs of sulfate, samples were also analyzed from an area of the same peatland that was previously amended with sulfate. Current additions of sulfate decreased dissolved organic carbon concentration and increased dissolved organic carbon aromaticity. Total dissolved phosphorus decreased in response to current sulfate amendments but was elevated in the area of the peatland recovering from sulfate amendment. The total dissolved phosphorus increase, which was reflected in microbial enzyme activity, may have shifted the system from P limitation to N limitation. This shift could have important consequences for ecosystem processes related to plant and microbial communities. It also suggests that the recovery from previous sulfate amendments may take longer than may be expected.
Bibliographical noteFunding Information:
The authors would like to thank researchers at the Northern Research Station of the USDA Forest service, including Deacon Kyllander, Carrie Dorrance and Dr. Stephen Sebestyen, who provided general assistance, watershed data, and information on trends of dissolved organic matter export. Thanks to Dr. John Pastor and Dr. Josef Werne for advice on study design and previous versions of this manuscript. This research was funded through the University of Minnesota-U.S. Environmental Protection Agency Cooperative training partnership ( CR83492801 ).
© 2014 Elsevier Ltd.
- Atmospheric deposition
- Dissolved organic carbon
- Microbial enzyme activity