Carbon dioxide emissions from a septic tank soakaway in a northern maritime climate.

Abstract

Here, we present the first attempt to quantify long-term and diurnal variations of CO2 fluxes from a soakaway of an on-site wastewater treatment system serving a single house located in a northern maritime climate (Ireland). An automated soil gas flux chamber system was deployed semi-continuously over a period of 17months, recording hourly flux measurements from the soakaway (Fsoak) and a control site (Fcontrol). Soil gas fluxes expressed seasonal and diurnal variations: Fsoak and Fcontrol ranged from 0.43 to 100.26μmolCO2m-2s-1 and 0.45 to 19.92μmolCO2m-2s-1 with median fluxes of 6.86 and 5.05μmolCO2m-2s-1, respectively. While temperature, soil water content, and atmospheric pressure were identified as the most significant environmental factors correlated to the release of CO2 from the control site, fluxes from the soakaway showed weaker correlations in regard to environmental factors. Assuming homogeneous spatial flux distributions, the soakaway emitted 15.0kgyr-1 more CO2 into the atmosphere in total compared to a similarly sized control site.