Seasonal variation in PCO₂ and ¹³C content of soil atmosphere

Soil carbon dioxide is the dominant source of dissolved inorganic carbon in recharging waters. Samples of soil CO 2 were collected to determine if seasonal variations in 13 C content parallel those previously observed for P CO 2 . Significant seasonal variations in both P CO 2 and 13 C content were observed. Studies of groundwater carbonate chemistry require knowledge of the season during which major recharge occurs.