Seasonal and spatial variability of polychlorinated biphenyls (PCBs) in vegetation and cow milk from a high altitude pasture in the Italian Alps

► A PCB peak in vegetation was found at the end of June. ► Higher PCB concentrations in vegetation were found in the Northern aspect. ► A temperature-dependent bioaccumulation process was found in the vegetation. ► A direct transfer of PCBs was found from vegetation to dairy milk. ► Carry-over ratios and bioaccumulation factors were calculated for dairy cow.