Abstract
Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8146-8164 |
| Number of pages | 19 |
| Journal | Water Resources Research |
| Volume | 51 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 1 2015 |
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Keywords
- agriculture
- artificial drainage
- dissolved organic carbon
- dissolved organic matter
- fluorescence
- hydrology
ASJC Scopus subject areas
- Water Science and Technology
Cite this
Hydrologic control of dissolved organic matter concentration and quality in a semiarid artificially drained agricultural catchment. / Bellmore, Rebecca A.; Harrison, John A.; Needoba, Joseph; Brooks, Erin S.; Kent Keller, C.
In: Water Resources Research, Vol. 51, No. 10, 01.10.2015, p. 8146-8164.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Hydrologic control of dissolved organic matter concentration and quality in a semiarid artificially drained agricultural catchment
AU - Bellmore, Rebecca A.
AU - Harrison, John A.
AU - Needoba, Joseph
AU - Brooks, Erin S.
AU - Kent Keller, C.
PY - 2015/10/1
Y1 - 2015/10/1
N2 - Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.
AB - Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.
KW - agriculture
KW - artificial drainage
KW - dissolved organic carbon
KW - dissolved organic matter
KW - fluorescence
KW - hydrology
UR - http://www.scopus.com/inward/record.url?scp=84956712638&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84956712638&partnerID=8YFLogxK
U2 - 10.1002/2015WR016884
DO - 10.1002/2015WR016884
M3 - Article
AN - SCOPUS:84956712638
VL - 51
SP - 8146
EP - 8164
JO - Water Resources Research
JF - Water Resources Research
SN - 0043-1397
IS - 10
ER -