In urban areas where there has been extensive reshaping of the land surface, disturbance from building and road construction, land-filling, and additions of a variety of chemicals and minerals, there are many sources, causes, and types of urban contamination. Urban contamination is of concern from two perspectives: when new land is developed that was previously under agriculture or other rural land use, and when the central core industrial areas are redeveloped. Sources of contamination can be summarized in three very broad categories: agricultural, urban, and industrial.

Agricultural-sourced contamination affects urban areas in several ways. Use of some pesticides in agricultural or gardening situations has increased by significant amounts the levels of copper, arsenic, and mercury in soils. Long-term use of phosphorus fertilizers can lead to a buildup of cadmium—a contaminant in many fertilizers—in soils. Synthetic organic pesticides used in agriculture can also contribute to...