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Particulate Organic Matter Composition in Stream Runoff Following Large Storms: Role of POM Sources, Particle Size, and Event Characteristics
Author(s) -
Johnson Erin R.,
Inamdar Shreeram,
Kan Jinjun,
Vargas Rodrigo
Publication year - 2018
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg004249
Subject(s) - environmental science , particulates , dissolved organic carbon , storm , watershed , sediment , total organic carbon , organic matter , environmental chemistry , surface runoff , hydrology (agriculture) , chemistry , geology , ecology , oceanography , geomorphology , geotechnical engineering , organic chemistry , biology , machine learning , computer science
Large storm events possess significant erosive energy capable of mobilizing large amounts of sediment and particulate organic matter (POM) into fluvial systems. This study investigated how stream POM composition varied as a function of the watershed POM source, particle size, storm event magnitude, and seasonal timing. POM composition was characterized for multiple watershed sources and for stream POM following storms in a second‐order forested stream. Carbon (C) and nitrogen (N) amount, C:N ratio and isotopic content ( 13 C and 15 N) were determined for solid phase POM, whereas dissolved organic C, total N concentrations, and fluorescence characteristics were determined for solution/extracted POM. Key findings from this study were the following: (1) Composition of POM varied greatly with watershed sources with forest floor litter being C and N rich and labile, while stream banks and bed were C and N poor and recalcitrant. (2) Summer storms mobilized more carbon and nitrogen‐rich labile sources, while winter events mobilized more carbon‐ and nitrogen‐poor refractory material from near‐stream sources. (3) POM composition varied by size class, with the coarse POM showing more C and N rich and labile properties, while the fine POM displayed more degraded and refractory properties. If climate variability increases the magnitude and intensity of large storm events, our observations suggest that this will not only increase the inputs of POM to aquatic systems but also result in the delivery of coarser, C and N rich, and more bioavailable POM to the stream drainage network.