Journal Article

Seasonal pattern of dissolved organic matter (DOM) in watershed sources: influence of hydrologic flow paths and autumn leaf fall

Singh, Shatrughan, Mitchell, Myron, Inamdar, Shreeram, McHale, Patrick

2014

Overview

Seasonal patterns of dissolved organic matter (DOM) were evaluated for multiple watershed sources and stream water during baseflow and stormflow to investigate the influence of hydrologic flow paths and key phenological events. Watershed sources sampled were throughfall, litter leachate, soil water, and deep groundwater. DOM data for a 4-year period (2008–2011) included: DOC concentrations and spectrofluorometric indices such as a₂₅₄, humification index, protein-like and humic-like DOM. Seasons were defined as—winter (December–February), spring (March–May), summer (June–September) and autumn (October and November). Seasonal differences in DOM were most pronounced for surficial flow paths (e.g., stormflow, litter leachate, throughfall and soil water) but muted or absent for groundwater and baseflow. This was attributed to the loss of DOM by sorption on mineral soil surfaces and/or microbial breakdown. DOM in summer stormflow had higher DOC concentrations and was more humic in character versus DOM in spring and winter runoff. Storm events in early autumn produced a sharp increase in DOC concentrations and % protein-like DOM for stream waters and litter leachate. Elevated DOC concentrations for early spring throughfall were attributed to leaching of organic exudates associated with leaf emergence. Our results underscore that watershed and ecosystem studies need to pay a greater attention to surficial flow paths and runoff sources (including stormflow) for understanding seasonal patterns of DOM. Understanding the influence of phenological episodes such as autumn leaf-fall for DOM is important considering that these transitional events may be especially affected by climate change.

• Publisher: Springer-Verlag,Springer,Springer International Publishing,Springer Nature B.V
• Subject: Animal and plant ecology / Animal, plant and microbial ecology / Aquatic ecosystems / Autumn / Base flow / Biogeosciences / Biological and medical sciences / Climate change / Dissolved organic carbon / Dissolved organic matter / Earth and Environmental Science / Earth Sciences / Earth, ocean, space / Ecosystem studies / Ecosystems / Environmental Chemistry / Exact sciences and technology / Exudates / Flow paths / Flowers & plants / Forest soils / Fundamental and applied biological sciences. Psychology / Groundwater / Groundwater data / Groundwater flow / Humification / Hydrogeology / Hydrology / Hydrology. Hydrogeology / Hypotheses / Initiatives / Leachates / Leaching / leaf abscission / leaf emergence / Leaf fall / Leaves / Life Sciences / Litter / Matter & antimatter / Microorganisms / mineral soils / Moisture content / Organic chemicals / phenology / Precipitation / Proteins / Rivers / Runoff / seasonal variation / Seasonal variations / Seasons / Soil / Soil surfaces / Soil water / sorption / Spring / Spring (season) / Storms / Stormwater / Stream water / Streams / Summer / Synecology / Terrestrial ecosystems / Throughfall / Water quality / Watershed management / Watersheds / Wetlands / Winter