2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/23/2019 | 10:15 AM - 10:30 AM | FLUORESCENCE SENSORS REVEAL IN-STREAM PROCESSING OF DISSOLVED ORGANIC MATTER IN RIVER NETWORKS | 251 AB

FLUORESCENCE SENSORS REVEAL IN-STREAM PROCESSING OF DISSOLVED ORGANIC MATTER IN RIVER NETWORKS

Levels of fluorescent dissolved organic matter (fDOM) in most freshwater ecosystems fluctuate on a daily basis. Yet the factors driving these changes are poorly quantified. We test the hypothesis that these changes are indicative of in-stream DOM processing, including photo-oxidation, ecosystem respiration, and primary production. To test this hypothesis, we used a network of fDOM sensors deployed in streams and rivers across the United States. We used temperature, shortwave radiation, canopy cover, and turbidity to decompose fDOM time series and disentangle the biotic and abiotic processes. Water clarity was a primary factor controlling fDOM processing, but the impact of turbidity and water color differed. Systems with high turbidity showed evidence of high respiration rates, but low levels of both photosynthesis and photo-oxidation. By contrast, high levels of fDOM in blackwater rivers led to low levels of photosynthesis, but evidence of high rates of photo-oxidation. Decreasing canopy cover and increasing temperature with watershed size were linked to greater diel fluctuation of fDOM. We conclude that overlapping signals of in-stream organic matter processing rates can be decomposed to infer rates of organic matter production and mineralization in freshwaters.

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Hydrology

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Presenters/Authors

Jacob Hosen (), Purdue University, jhosen@purdue.edu;