Nitrous oxide supersaturation at the liquid/air interface of animal waste

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Department of Biological Sciences


Concentrated animal feeding operations around the globe generate large amounts of nitrous oxide (N 2O) in the surrounding atmosphere. Liquid animal waste systems have received little attention with respect to N 2O emissions. We hypothesized that the solution chemistry of animal waste aqueous suspensions would promote conditions that lead to N 2O supersaturation at the liquid/air interface. The concentration of dissolved N 2O in poultry litter (PL) aqueous suspensions at 25 °C was 0.36 μg N 2O mL -1, at least an order of magnitude greater than that measured in water in equilibrium with ambient air, suggesting N 2O supersaturation. There was a nonlinear increase in the N 2O Henry constants of PL from 2810 atm/mole fraction at 35 °C to 17 300 atm/mole fraction at 41 °C. The extremely high N 2O Henry constants were partially ascribed to N 2O complexation with aromatic moieties. Complexed N 2O structures were unstable at temperatures > 35 °C, supplying the headspace with additional free N 2O concentrations.

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© 2009 Elsevier Ltd. All rights reserved. Publisher’s version of record: https://doi.org/10.1016/j.envpol.2009.06.006

Publication Title

Environmental Pollution