Long-Distance Transport of Urban and Industrial Metals and Their Incorporation into the Environment: Sources, Transport Pathways and Historical Trends

Abstract

This paper reviews the long-range transport of toxic metal pollutants through the atmosphere and their incorporation into the environment. Metals remain among the most pervasive contaminants, because they are transported far from their point-sources and are found even in remote regions. Metal pollution has a long history, with geologic archives documenting its onset ~5000 years ago. Peak metal pollution in Europe and North America occurred in the 1970s, but has subsequently declined in part following health concerns. However, it appears to be increasing downwind of Asia, which is experiencing rapid industrialisation. Data on metal pollution are scarce from many regions, including Africa and South America. Few studies have examined long-range metal pollution in urban environments, where local pollution often masks the long-range component; however, this is likely to be a significant pollution source in many urban settings. Metal pollution remains a significant health concern as toxicology studies now imply that any exposure to Pb and Hg is potentially harmful. In addition, recent studies show historical metal pollution, stored within the Earth’s surface sediments and water bodies, can be remobilized, again causing impacts.