Bioavailability of dissolved organic carbon across a hillslope chronosequence in the Kuparuk River region, Alaska

Kyle A. Whittinghill, Jacques C Finlay, Sarah E Hobbie

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5 Citations (Scopus)

Abstract

Dissolved organic matter (DOM) represents an important component of carbon and nutrient cycling in arctic ecosystems. In northern Alaska, DOM production and microbial activity differ among landscapes with varied glaciation histories with lower rates on younger landscapes. In addition, within the region, soil DOM concentrations vary at the scale of hillslope toposequences, with higher concentrations in upslope than streamside positions. However, it is unknown whether variation in DOM production quality among and within landscapes linked to patterns in DOM quality. To answer this question, we conducted a study of DOM biodegradability within and among hillslopes of different landscape age. We examined rates of DOM decomposition and several indices of the quality of water-extracted DOM collected from soils in the summer. A variety of methods indicated that DOM quality generally was consistent across hillslope positions and among landscape ages. For example, DOM fluorescence index, an index of quality for chromophoric DOM, did not vary significantly across all hillslope positions or landscape ages. There were no significant differences among landscape ages or hillslope positions in DOM specific UV absorbance, in rates of DOM mineralization, or in DOM decomposition, indicating that DOM quality was consistent regardless of its source or position along hillslope flow paths. This suggests that despite many potential sources of variation within and among arctic hillslopes linked to differences in vegetation, hydrology, microclimate, and microbial activity, there is little variation in growing-season soil DOM quality. Microbial processing of DOM within arctic hillslopes may lead to a convergence in growing season DOM quality resulting in little spatial variation. Approximately 10-20% of the growing season DOM is labile in tundra soils, slightly higher that the proportion that is labile in arctic rivers during the summer.

Original languageEnglish (US)
Pages (from-to)25-33
Number of pages9
JournalSoil Biology and Biochemistry
Volume79
DOIs
StatePublished - Dec 1 2014

Fingerprint

chronosequences
chronosequence
dissolved organic matter
dissolved organic carbon
hillslope
Rivers
Biological Availability
bioavailability
Soil
Carbon
rivers
river
Hydrology
Microclimate
Water Quality
Ecosystem
Fluorescence
Arctic region
Food
growing season

Keywords

  • Arctic
  • Decomposition
  • Dissolved organic carbon
  • Landscape age
  • Topography

Cite this

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title = "Bioavailability of dissolved organic carbon across a hillslope chronosequence in the Kuparuk River region, Alaska",
abstract = "Dissolved organic matter (DOM) represents an important component of carbon and nutrient cycling in arctic ecosystems. In northern Alaska, DOM production and microbial activity differ among landscapes with varied glaciation histories with lower rates on younger landscapes. In addition, within the region, soil DOM concentrations vary at the scale of hillslope toposequences, with higher concentrations in upslope than streamside positions. However, it is unknown whether variation in DOM production quality among and within landscapes linked to patterns in DOM quality. To answer this question, we conducted a study of DOM biodegradability within and among hillslopes of different landscape age. We examined rates of DOM decomposition and several indices of the quality of water-extracted DOM collected from soils in the summer. A variety of methods indicated that DOM quality generally was consistent across hillslope positions and among landscape ages. For example, DOM fluorescence index, an index of quality for chromophoric DOM, did not vary significantly across all hillslope positions or landscape ages. There were no significant differences among landscape ages or hillslope positions in DOM specific UV absorbance, in rates of DOM mineralization, or in DOM decomposition, indicating that DOM quality was consistent regardless of its source or position along hillslope flow paths. This suggests that despite many potential sources of variation within and among arctic hillslopes linked to differences in vegetation, hydrology, microclimate, and microbial activity, there is little variation in growing-season soil DOM quality. Microbial processing of DOM within arctic hillslopes may lead to a convergence in growing season DOM quality resulting in little spatial variation. Approximately 10-20{\%} of the growing season DOM is labile in tundra soils, slightly higher that the proportion that is labile in arctic rivers during the summer.",
keywords = "Arctic, Decomposition, Dissolved organic carbon, Landscape age, Topography",
author = "Whittinghill, {Kyle A.} and Finlay, {Jacques C} and Hobbie, {Sarah E}",
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TY - JOUR

T1 - Bioavailability of dissolved organic carbon across a hillslope chronosequence in the Kuparuk River region, Alaska

AU - Whittinghill, Kyle A.

AU - Finlay, Jacques C

AU - Hobbie, Sarah E

PY - 2014/12/1

Y1 - 2014/12/1

N2 - Dissolved organic matter (DOM) represents an important component of carbon and nutrient cycling in arctic ecosystems. In northern Alaska, DOM production and microbial activity differ among landscapes with varied glaciation histories with lower rates on younger landscapes. In addition, within the region, soil DOM concentrations vary at the scale of hillslope toposequences, with higher concentrations in upslope than streamside positions. However, it is unknown whether variation in DOM production quality among and within landscapes linked to patterns in DOM quality. To answer this question, we conducted a study of DOM biodegradability within and among hillslopes of different landscape age. We examined rates of DOM decomposition and several indices of the quality of water-extracted DOM collected from soils in the summer. A variety of methods indicated that DOM quality generally was consistent across hillslope positions and among landscape ages. For example, DOM fluorescence index, an index of quality for chromophoric DOM, did not vary significantly across all hillslope positions or landscape ages. There were no significant differences among landscape ages or hillslope positions in DOM specific UV absorbance, in rates of DOM mineralization, or in DOM decomposition, indicating that DOM quality was consistent regardless of its source or position along hillslope flow paths. This suggests that despite many potential sources of variation within and among arctic hillslopes linked to differences in vegetation, hydrology, microclimate, and microbial activity, there is little variation in growing-season soil DOM quality. Microbial processing of DOM within arctic hillslopes may lead to a convergence in growing season DOM quality resulting in little spatial variation. Approximately 10-20% of the growing season DOM is labile in tundra soils, slightly higher that the proportion that is labile in arctic rivers during the summer.

AB - Dissolved organic matter (DOM) represents an important component of carbon and nutrient cycling in arctic ecosystems. In northern Alaska, DOM production and microbial activity differ among landscapes with varied glaciation histories with lower rates on younger landscapes. In addition, within the region, soil DOM concentrations vary at the scale of hillslope toposequences, with higher concentrations in upslope than streamside positions. However, it is unknown whether variation in DOM production quality among and within landscapes linked to patterns in DOM quality. To answer this question, we conducted a study of DOM biodegradability within and among hillslopes of different landscape age. We examined rates of DOM decomposition and several indices of the quality of water-extracted DOM collected from soils in the summer. A variety of methods indicated that DOM quality generally was consistent across hillslope positions and among landscape ages. For example, DOM fluorescence index, an index of quality for chromophoric DOM, did not vary significantly across all hillslope positions or landscape ages. There were no significant differences among landscape ages or hillslope positions in DOM specific UV absorbance, in rates of DOM mineralization, or in DOM decomposition, indicating that DOM quality was consistent regardless of its source or position along hillslope flow paths. This suggests that despite many potential sources of variation within and among arctic hillslopes linked to differences in vegetation, hydrology, microclimate, and microbial activity, there is little variation in growing-season soil DOM quality. Microbial processing of DOM within arctic hillslopes may lead to a convergence in growing season DOM quality resulting in little spatial variation. Approximately 10-20% of the growing season DOM is labile in tundra soils, slightly higher that the proportion that is labile in arctic rivers during the summer.

KW - Arctic

KW - Decomposition

KW - Dissolved organic carbon

KW - Landscape age

KW - Topography

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