Production of CO2 in the capillary fringe of a deep phreatic aquifer

摘要: CO2 profiles obtained along a 30-m-thick unsaturated zone under land irrigated with sewage effluents show two production regions: seasonal one in the root and another, at steady state, near water table (29 m). On an annual basis flux from deep source toward atmosphere (6.3 g C m−2 yr−1) is balanced by similar influx of soluble organic carbon (SOC) effluents. The δ13C values soil indicate that produced plant material biodegradation total sedimentary capillary fringe. High concentration fringe (up to 2%) likely reflect decrease diffusivity relative due increase both content tortuosity induced structure. long residence time SOC years study site) suggests aquifers may have significant storage capacity for act as temporary sink.