Event Title

Characterization of sources of organic matter to an urban river

Presenter Information

Julie Kelso
Dave Epstein
Michelle Baker

Location

Eccles Conference Center

Event Website

http://water.usu.edu

Start Date

1-4-2014 4:45 PM

End Date

1-4-2014 4:50 PM

Description

Organic matter in undisturbed aquatic systems has been well characterized, but urban studies reveal less understood sources such stormwater and wastewater effluent. Urban systems may alter the quality of organic matter inputs with unknown consequences to nutrient cycling. We characterized the signature of source particulate organic matter using three stable isotopes (13C, 15N, 2H) and elemental ratios. Dissolved organic matter was characterized using a fluorescence index (FI), specific UVA absorbance (SUVA), and the 13C signature of dissolved organic carbon (DOC). Coarse particulate organic matter (CPOM) and seston were collected along seven reaches of an urban river. We found that CPOM was primarily composed of allocthonous sources (litterfall and riparian vegetation) and seston was composed of periphyton. Macrophytes contributed to both CPOM and seston. The DOC isotopic signature ranged from -24.4 to -26.8 ‰ 13C, which was between 13C isotopic values for autochthonous (-23.6to -19.7 ‰ 13C ) and allochthonous (-24.2 to -31.7‰ 13C ) sources suggesting dissolved organic matter is a mix of the two sources. In addition, nitrogen isotope values of seston increased with proximity to wastewater effluent (5.2 to 10.9 ‰ 15N).

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Apr 1st, 4:45 PM Apr 1st, 4:50 PM

Characterization of sources of organic matter to an urban river

Eccles Conference Center

Organic matter in undisturbed aquatic systems has been well characterized, but urban studies reveal less understood sources such stormwater and wastewater effluent. Urban systems may alter the quality of organic matter inputs with unknown consequences to nutrient cycling. We characterized the signature of source particulate organic matter using three stable isotopes (13C, 15N, 2H) and elemental ratios. Dissolved organic matter was characterized using a fluorescence index (FI), specific UVA absorbance (SUVA), and the 13C signature of dissolved organic carbon (DOC). Coarse particulate organic matter (CPOM) and seston were collected along seven reaches of an urban river. We found that CPOM was primarily composed of allocthonous sources (litterfall and riparian vegetation) and seston was composed of periphyton. Macrophytes contributed to both CPOM and seston. The DOC isotopic signature ranged from -24.4 to -26.8 ‰ 13C, which was between 13C isotopic values for autochthonous (-23.6to -19.7 ‰ 13C ) and allochthonous (-24.2 to -31.7‰ 13C ) sources suggesting dissolved organic matter is a mix of the two sources. In addition, nitrogen isotope values of seston increased with proximity to wastewater effluent (5.2 to 10.9 ‰ 15N).

http://digitalcommons.usu.edu/runoff/2014/2014Posters/28