Event Title

Light Degraded Dissolved Organic Matter Increased The Decay Rate of Terrestrial Organic Matter in Experimental Streams

Presenter Information

Julie Kelso
Emma Rosi
Michelle Baker

Location

Logan Country Club

Streaming Media

Start Date

3-28-2017 2:20 PM

End Date

3-28-2017 2:25 PM

Description

Dissolved organic matter (DOM) is the largest pool of organic matter (OM) in aquatic systems and mediates all microbial processes. Terrestrial biogeochemists have described the process priming, during which additions of labile OM accelerate decomposition of semi-labile OM. We tested for priming of terrestrial, semi-labile DOM in 8 experimental streams and dark bottles. Decay of 2 forms of semi-labile DOM, soil leachate and plant leachate, 2 forms of labile DOM, algal leachate and light degraded semi-labile DOM, and a mixture of labile and semi-labile DOM were measured. Decay rates of soil leachate were too low to measure and plant leachate decay averaged 0.011/hr in streams and 0.001/hr in bottles (S.D. 0.002/hr ; 0.001/hr). Algal leachate decay averaged 0.025/hr in streams and 0.005/hr in bottles (S.D. 0.021/hr ; 0.002/hr). When algal leachate was mixed with semi-labile plant leachate decay rates were similar to plant leachate alone. However, when light-degraded plant leachate was added to semi-labile leachate, decay rates were greater than plant leachate alone (Avg. 0.051/hr; S.D. 0.015/hr). We concluded exposure to light increased lability of terrestrially derived DOM, and could increase consumption rates of non-labile DOM. A greater understanding of differences in decay depending on the composition of DOM could inform models that attempt to predict the effects of increased OM loads in rivers systems, for example QUAL2K models.

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Mar 28th, 2:20 PM Mar 28th, 2:25 PM

Light Degraded Dissolved Organic Matter Increased The Decay Rate of Terrestrial Organic Matter in Experimental Streams

Logan Country Club

Dissolved organic matter (DOM) is the largest pool of organic matter (OM) in aquatic systems and mediates all microbial processes. Terrestrial biogeochemists have described the process priming, during which additions of labile OM accelerate decomposition of semi-labile OM. We tested for priming of terrestrial, semi-labile DOM in 8 experimental streams and dark bottles. Decay of 2 forms of semi-labile DOM, soil leachate and plant leachate, 2 forms of labile DOM, algal leachate and light degraded semi-labile DOM, and a mixture of labile and semi-labile DOM were measured. Decay rates of soil leachate were too low to measure and plant leachate decay averaged 0.011/hr in streams and 0.001/hr in bottles (S.D. 0.002/hr ; 0.001/hr). Algal leachate decay averaged 0.025/hr in streams and 0.005/hr in bottles (S.D. 0.021/hr ; 0.002/hr). When algal leachate was mixed with semi-labile plant leachate decay rates were similar to plant leachate alone. However, when light-degraded plant leachate was added to semi-labile leachate, decay rates were greater than plant leachate alone (Avg. 0.051/hr; S.D. 0.015/hr). We concluded exposure to light increased lability of terrestrially derived DOM, and could increase consumption rates of non-labile DOM. A greater understanding of differences in decay depending on the composition of DOM could inform models that attempt to predict the effects of increased OM loads in rivers systems, for example QUAL2K models.