Dissolved Organic Matter Compositional Change and Biolability During Two Storm Runoff Events in a Small Agricultural Watershed
| Autor: | Sandra M. Bachand, Brian A. Bergamaschi, Peter J. Hernes, Philip A.M. Bachand, Robert G. M. Spencer, Robert S. Eckard, Brian A. Pellerin |
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| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_classification
Total organic carbon Hydrology Atmospheric Science 010504 meteorology & atmospheric sciences Ecology Stormwater First flush Paleontology Soil Science Forestry 010501 environmental sciences Aquatic Science 01 natural sciences Hydrology (agriculture) chemistry Soil water Dissolved organic carbon Environmental science Organic matter Surface runoff 0105 earth and related environmental sciences Water Science and Technology |
| Zdroj: | Journal of Geophysical Research: Biogeosciences. 122:2634-2650 |
| ISSN: | 2169-8953 |
| DOI: | 10.1002/2017jg003935 |
| Popis: | Agricultural watersheds are globally pervasive, supporting fundamentally different organic matter source, composition, and concentration profiles in comparison to natural systems. Similar to natural systems, agricultural storm runoff exports large amounts of organic carbon from agricultural land into waterways. But intense management of upper soil layers, waterway channelization, wetland and riparian habitat removal, and post-harvest vegetation removal promise to uniquely drive organic matter release to waterways. During a winter first flush and a subsequent storm event, this study investigated the influence of a small agricultural watershed on dissolved organic matter (DOM) source, composition, and biolability. Stormwater discharge released strongly terrestrial yet biolabile (23 to 32%) dissolved organic carbon (DOC). Following a 21 day bioassay, a parallel factor (PARAFAC) analysis identified an 80% reduction in a protein-like (phenylpropyl) component (C2) that was previously correlated to lignin phenol concentration, and a 10% reduction in a humic-like, terrestrially sourced component (C4). Storm-driven releases tripled DOC concentration (from 2.8 to 8.7 mg L-1) during the first flush event in comparison to base flow, and were terrestrially sourced, with an 8-fold increase in vascular plant derived lignin phenols (23.0 to 185 μg L-1). As inferred from system hydrology, lignin composition, and nitrate as a groundwater tracer, an initial pulse of dilute water from the upstream watershed caused a counterclockwise DOC hysteresis loop. DOC concentrations peaked after 3.5 days, with the delay between peak discharge and peak DOC attributed to stormwater hydrology and a period of initial water repellency of agricultural soils, which delayed DOM leaching. |
| Databáze: | OpenAIRE |
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