Legacy problems in urban geochemistry

Modern cities are affected by multiple sources of contamination and pollution, the effects of which overlap in space and time. Toxic metal contamination, organic pollution, smog, acid rain, and greenhouse gas accumulation are the most widespread legacies of an often uncontrolled growth that has deeply changed the geochemical character of the urban environment over the last four millennia. Even though progress has changed human habits and positively influenced the quality of city life, the past is frequently a hidden source of environmental problems with the potential to affect the health of current and future urban residents.