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Determination of the effect of temperature (Q10) on denitrification rates in sediments collected from a groundwater discharge site in Ashumet Pond on Cape Cod, MA

February 5, 2021

This data release presents results from a laboratory study designed to measure the effect of temperature on denitrification rates in sediments collected from 5- to 30-cm depth below the lake bottom, at a location where groundwater discharges to the lake. Sediment cores were collected June 25, 2014 from the West site (Fishermans Cove) in Ashumet Pond, Cape Cod, MA then shipped to Boulder, CO for laboratory experiments. Groundwater used for these experiments was collected from a well just upgradient of the sediment collection site. Denitrification rates were determined on sediment plus groundwater slurries maintained under anaerobic conditions and employing the acetylene block method. Nitrous oxide concentrations were measured several times over the course of an approximately 7-hour period in serum bottles containing 30 g sieved sediment (less than 2mm) combined with 30 mL filtered groundwater at 3 different incubation temperatures (4, 15, 24 degrees Celsius). Denitrification rates were calculated based on the accumulation of nitrous oxide over time in the serum bottles. The temperature coefficient, Q10, for the sediment in Ashumet Pond was calculated using these denitrification rates and was determined to be 4.9, meaning that the rate of denitrification increased by a factor of 4.9 for every 10 degrees of temperature increase.

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