A number of methods exist for estimating mineral weathering rates.	Yet, quantifying this crucial biogeochemical reaction in the field	has always been a challenge because mineral weathering takes place	in open systems whose initial state conditions are not well known	and where material inputs and outputs vary in time and space. Here,	using the soil profile mass balance method, we estimated long-term	weathering rates of base cations (BCs) for a set of 21 watersheds,	and we investigated the links between environmental variables and	soil properties and the spatial variation in BC weathering rates	in the study area. The watersheds are located in southern Quebec	and vary with respect to hydro-climatic conditions, soil properties	and forest cover. Average long-term estimates of annual BC weathering	rates for the study area were 0.16, 0.10, 0.09 and 0.06kmolcha-1year-1	for Ca, Mg, Na and K, respectively. Overall, redundancy analysis	(RDA) indicated that soil surface area, percent deciduous canopy	cover, elevation, as well as soil albite content were the most significant	variables explaining together 56% of the total variation in BC weathering	rates. Consistent with previous findings, our results showed that,	beside soil properties, climate-related environmental variables played	key roles in determining the variability of BC weathering rates in	the study area. In the context of global climate change, more insights	are needed for a better understanding of the effects of discrete	climatic variables on BC weathering rates. © 2015 .