Sources of lead in soils

Lead in soils can originate from vehicle emissions, the mixing of lead-based paint in soils and lead bullets in pistol shooting ranges. In this post, I will first discuss lead in soils from vehicle emissions. 

In 1970, Motto, H. L., et al. sampled the soils along heavily travelled highways of New Jersey, Pennsylvania and Maryland and concluded that lead contents in soils tend to increase with traffic volume and decrease with distance from the highway. The lead in road soils origin from usage of leaded petrol. The lead in soils are very persistent as soil colloids bind firmly to tetraethyllead released from the combustion of leaded petrol in vehicles. If humans ingest dust particles contaminated with Pb overtime, Pb poisoning may occur. Crops grown at the vicinity of highways are also found to be contaminated with Pb. This may also result in Pb poisoning. If neighborhoods are situated near heavy traffic roads, children are especially vulnerable if they play with soils.

Picture showing the process of cleaning and recovery of
lead contaminated soils. Taken from:
https://www.youtube.com/watch?v=fFRs6xfAILY

While leaded petrol has been banned in many developed countries, developing countries have lax rules regarding leaded petrol. In 2013, British company Innospec Ltd was found to be selling tetraethyl lead to improvised countries such as Iraq and Algeria through bribery (Telegraph Reporters, 2013). There is a need to ban leaded petrol in developing countries as these countries do not have the capacity to deal with lead cleaning of soils, which is expensive and time-consuming. 

References

McCarthy, M. (2000) Lead-free petrol may be villain in mystery of demise of the world's most familiar bird. Online. Available at: http://www.independent.co.uk/environment/leadfree-petrol-may-be-villain-in-mystery-of-demise-of-the-worlds-most-familiar-bird-698469.html

Motto, H. L. (1970) Lead in Soils and Plants: Its Relationship to Traffic Volume and Proximity to Highways. Environ. Sci. Technol., Vol. 4 (3), pp 231–237. 

Telegraph Reporters (2013) British company 'selling toxic lead fuel to poor countries'. Online. Available at: http://www.telegraph.co.uk/news/earth/energy/9800019/British-company-selling-toxic-lead-fuel-to-poor-countries.html