Event Title

Characterization of Dissolved Organic Matter Fluorescence Along a Mountain To Urban Gradient of Land Use

Presenter Information

Julie Kelso

Location

USU Eccles Conference Center

Event Website

http://water.usu.edu

Start Date

4-5-2016 4:45 PM

End Date

4-5-2016 4:48 PM

Description

Dissolved organic matter (DOM) is the largest pool of organic carbon in aquatic ecosystems, and in spite of decades of study, remains a mysterious mixture of labile and non-labile compounds. We hypothesized anthropogenic changes in land use have increased the proportion of labile DOM in river ecosystems. We sampled DOM at 16 sites in the Provo, Red Butte Creek, and Logan River watersheds. Percent agriculture, urban and grazing landuse within each watershed was calculated and correlated to DOM properties. Samples were analyzed for inorganic nutrient concentrations, dissolved organic carbon (DOC), nitrogen (DON), spectrofluorometric indices including the fluorescence (FI), and specific UV absorbance (SUVA). FI values ranged from 1.4 to 1.7 representing a range in DOM derived from both microbial and terrestrial sources. DOC concentrations were negatively correlated with the FI and positively correlated with phosphorus concentrations suggesting sites with high DOC concentrations have proportionally more recalcitrant DOM than labile DOM. This study can help identify sources of DOM as well as shed light on the complex interactions between inorganic nutrients and organic matter inputs in watersheds with varying landuse.

Comments

A poster by Julie Kelso, who is with Utah State University, Department of Biology

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Apr 5th, 4:45 PM Apr 5th, 4:48 PM

Characterization of Dissolved Organic Matter Fluorescence Along a Mountain To Urban Gradient of Land Use

USU Eccles Conference Center

Dissolved organic matter (DOM) is the largest pool of organic carbon in aquatic ecosystems, and in spite of decades of study, remains a mysterious mixture of labile and non-labile compounds. We hypothesized anthropogenic changes in land use have increased the proportion of labile DOM in river ecosystems. We sampled DOM at 16 sites in the Provo, Red Butte Creek, and Logan River watersheds. Percent agriculture, urban and grazing landuse within each watershed was calculated and correlated to DOM properties. Samples were analyzed for inorganic nutrient concentrations, dissolved organic carbon (DOC), nitrogen (DON), spectrofluorometric indices including the fluorescence (FI), and specific UV absorbance (SUVA). FI values ranged from 1.4 to 1.7 representing a range in DOM derived from both microbial and terrestrial sources. DOC concentrations were negatively correlated with the FI and positively correlated with phosphorus concentrations suggesting sites with high DOC concentrations have proportionally more recalcitrant DOM than labile DOM. This study can help identify sources of DOM as well as shed light on the complex interactions between inorganic nutrients and organic matter inputs in watersheds with varying landuse.

https://digitalcommons.usu.edu/runoff/2016/2016Posters/6