Changes in dissolved organic matter quality in a northern hardwood forest revealed by excitation emission spectroscopy
Abstract
Changes in dissolved organic matter (DOM) quality may result from unusual and extreme precipitation patterns such as floods and droughts. In order to study DOM quality changes, we collected several hundred surface water samples during the past eight years from the W-9 watershed of the Sleepers River Research Watershed in Danville, Vermont for optical analysis of dissolved organic matter. We present the results of parallel factor (PARAFAC) and principal component analysis (PCA) on excitation emission matrices (EEMs). This analysis revealed that peaks T, C and M as identified by PARAFAC were the most prominent EEM features. The intensity of these peaks varied on inter-annual, seasonal and event time periods and these shifts reflect changes in DOM quality. Likely drivers of this variability in DOM chemistry are seasonal shifts in flow paths, antecedent moisture conditions, and precipitation duration and intensity. For example, during events, the relative proportion of protein-like, peak T fluorophores increased, likely from flushing of fresh polyphenols from surficial and shallow flow paths. During the winter, when groundwater dominates flow, EEMs were strong in humic-like peak C and peak M fluorophores, reflecting deeper soil sources and longer flow paths. Our analyses will reveal how DOM quality responds to climatic drivers, and thus how we can expect DOM quality to evolve under projected climate change scenarios.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMEP23B0968S
- Keywords:
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- 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0483 Riparian systems;
- BIOGEOSCIENCESDE: 1820 Floodplain dynamics;
- HYDROLOGYDE: 1856 River channels;
- HYDROLOGY