Fig. 2From: Transport and retention of micro-polystyrene in coarse riverbed sediments: effects of flow velocity, particle and sediment sizesPS retention profiles for the gravel packed columns operated with flow rates (Q) of about 38 ml min−1 (a, Q38_mGr), 20 ml min−1 (b, Q20_mGr) and 4 ml min−1 (c, Q4_mGr)Back to article page