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.