Dissolved organic carbon concentration and flux in a grassland stream: spatial and temporal patterns and processes from long-term data

被引：0
作者：
Janine Rüegg
Jessica J. Eichmiller
Natalie Mladenov
Walter K. Dodds
机构：
[1] Kansas State University,Division of Biology
[2] University of Minnesota Twin Cities,Department of Fisheries, Wildlife, and Conservation Biology
[3] San Diego State University,Department of Civil Construction and Environmental Engineering
来源：
Biogeochemistry | 2015年 / 125卷
关键词：
Prairie streams; Carbon cycle; Long-term study; Carbon export;
D O I：
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中图分类号：
学科分类号：
摘要：
Dissolved organic carbon (DOC) in streams is a critical component of the global carbon cycle, but little is known about long-term patterns in DOC concentration and export in grassland streams. Here we present the results of a 15-year dataset collected from multiple sites in the Kings Creek watershed on Konza Prairie, KS, USA. DOC concentrations ranged from 0.15 to 15.97 mg L−1, with a mean of 1.19 mg L−1 (standard deviation 1.01 mg L−1). Sites differed in their DOC concentrations as a function of the year of study and the season. Generally, headwaters had greater DOC concentrations, and DOC decreased downstream. The lowest concentrations were found in a groundwater spring in the watershed. Concentrations showed no trend over the study and were not correlated with discharge. However, annual export (mean: 0.29 kg ha−1 year−1; range: 0.00–9.09 kg ha−1 year−1) was highly correlated with annual runoff, and annual runoff explained over 80 % of the variation in export. Export from Kings Creek was 30 times lower than the literature-reported mean for grasslands and 137 times less than export averaged across all biomes. Neither fire nor bison, two forces that maintain prairies, were statistically related to DOC concentrations. Main drivers of DOC concentrations are likely leaching from terrestrial organic material in soils and the accumulations in dry streambeds during drought periods as well as instream autotrophic production. Downstream declines in DOC concentrations suggest instream processing. Grassland streams probably have modest effects on the global carbon budget due to instream processing and low precipitation. Changes in precipitation may have large effects on carbon export from grassland streams.
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页码：393 / 408
页数：15
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