Police arrested 12 activists from the group Kappen met Kolen on Saturday at the coal railway of the EECV transshipment terminal in Rotterdam's Europoort. The activists were trying to draw attention to the negative impact of coal on the environment.The activists had planned to remove ballast stones from under the track and use them to build a monument to the cycle of life, the group told AD. Rotterdam police, however, were present in large numbers and prevented the participants from carrying out the action.