Chlorobenzenes in rivers draining industrial catchments

Area of Science:

• Environmental Chemistry
• Water Quality Monitoring
• Pollutant Source Apportionment

Background:

• Chlorobenzenes are industrial chemicals with varying environmental persistence.
• Understanding their sources and transport in river systems is crucial for water quality management.
• Previous studies have not quantified chlorobenzene fluxes from UK catchments to the sea.

Purpose of the Study:

• To monitor chlorobenzene concentrations in four major rivers of the Southern Humber Catchment.
• To differentiate between industrial and domestic sources of chlorobenzene pollution.
• To calculate the annual flux of chlorobenzenes from the catchment into the Humber estuary.

Main Methods:

• Weekly monitoring of eleven chlorobenzene congeners in whole water samples.
• Analysis of rivers Aire, Calder, Don, and Trent over a defined period.
• Calculation of chlorobenzene fluxes based on measured concentrations and river discharge.

Main Results:

• The Aire and Calder rivers exhibited higher total chlorobenzene concentrations compared to the Don and Trent.
• 1,2- and 1,4-dichlorobenzene were prevalent, with 1,4-dichlorobenzene dominating on the Don and Trent.
• Industrial sources were indicated for the Aire and Calder, while domestic sources were inferred for the Don and Trent.
• Total chlorobenzene flux to the Humber estuary was estimated at 133 kg/year, with 1,4-dichlorobenzene being the major contributor.

Conclusions:

• River pollution by chlorobenzenes varies significantly between industrial and domestic sources.
• The Southern Humber Catchment exports substantial amounts of chlorobenzenes to the North Sea.
• This study provides the first quantitative assessment of chlorobenzene fluxes to the North Sea from a UK catchment.