Radon-traced pore-water as a potential source of CO2 and CH4 to receding black and clear water environments in the Amazon Basin

Here we report coupled, high resolution measurements of pCO2, CH4 and 222Rn during receding waters in the three major water types of the Central Amazon Basin: black (Negro River); clear (Tapajos River); white (Madeira River). Considerable spatial heterogeneity was observed in pCO2, CH4 and 222Rn concentrations ranging from 460 to 8030 uatm, 7 to 281 nM, and 713 to 8516 dpm m-3, respectively. the significant correlations between pCO2 and CH4 to 222Rn in the black and clear waters suggests that pore-water further enhanced CO2 supersaturation by 18 - 47 % and is a driver of CH4 dynamics in these waters.