Chlorobenzenes in field soil with a history of multiple sewage sludge applications

Data from an experiment involving multiple sludge applications to agricultural land in the UK from 1942 to 1961 were examined to understand the long-term behavior of chlorobenzenes (CBs) in sewage sludge-amended soils. The results showed that 10% of CBs have remained in amended soils up to the 1990s, while the rest have been lost mainly through volatilization soon after soil amendment. Hexachlorobenzene is the most persistent CB, remaining 10 years longer than other CBs. 1,4-dichlorobenzene increased during the 1960s in both experimental and control soils, probably from atmospheric deposition and trace level impurities in pesticides.