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Temperature Effects on Greenhouse Gas Production
From Treatment Wetland Soils Along a Nutrient Gradient

By: Kyle Dittmer and Havalend Steinmulle | Mentor: Dr. Lisa Chambers

Abstract

It is generally accepted that increased temperatures are positively correlated with microbial respiration rates, causing greater greenhouse gas (GHG) emissions (CO2 and CH4) from wetlands. The goal of this study was to understand the interacting effects of temperature and nutrient concentrations on GHG emissions from wetland soils. Complementary field studies and a laboratory study were completed within Cell 1 of the Orlando Wetlands Park (Christmas, FL). Four sampling locations were established along a transect and sampled in summer and winter for the field studies. Soils (0-10 cm) were incubated under anaerobic conditions for 48-hours at ambient or elevated temperatures and GHG flux was measured. Surface water nutrients and soil physiochemical properties were also analyzed. Carbon dioxide and methane production both differed through an interaction between season and site (p = 0.04 and p < 0.001, respectively) with higher rates in the summer and at sites with the higher soil organic matter; water nutrients did not have a significant effect on GHG emissions. The laboratory study used only one soil sample, but varied water nutrients and temperature (3 x 3 factorial design) using four replicates per treatment and incubating under anaerobic conditions for 10 days. Temperature had a significant effect on both CO2 and CH4 production (both p < 0.001), but water nutrients did not have an effect, presumably due to exiting high nutrient levels within the soil porewater. These results highlight the importance of soil properties (organic matter content and porewater nutrients) when determining the influence of temperature and water nutrients on GHG production.

KEYWORDS: wetland; treatment wetland; greenhouse gasses; eutrophication; climate change; biogeochemistry; soil

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