Composition and age of dissolved organic matter affect bacterial diversity during groundwater recharge events

We evaluated a 3-year time series of DOM composition and age using ultrahigh-resolution mass spectrometry and its radiocarbon (14C) content along a multi-well transect of a fractured bedrock groundwater system with different landuses in hillslope terrain. The diversity of the groundwater bacteria community responded to the seasonally varying DOM pool, suggesting that surface-connection and seasonal flow variation are important controls of the groundwater microbial community.