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Penetration of herbicides to groundwater in an unconfined chalk aquifer following normal soil applications

Johnson, Andrew; Besien, T.J.; Bhardwaj, C.L.; Dixon, A.; Gooddy, Daren; Haria, A.H.; White, C.. 2001 Penetration of herbicides to groundwater in an unconfined chalk aquifer following normal soil applications. Journal of Contaminant Hydrology, 53 (1-2). 101-117. 10.1016/S0169-7722(01)00139-5

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Abstract/Summary

The persistence and penetration of the herbicides isoproturon and chlorotoluron in an unconfined chalk aquifer has been monitored over a 4-year period through soil sampling, shallow coring and groundwater monitoring. Chlorotoluron was applied on plots as a marker compound, having never been used previously on that, or surrounding fields. The fieldsite had a 5 degrees slope with soil depths of 0.5 to 1.5 m and a water table between 20 and 5 m from the soil surface. Where the water table was deepest (9-20 m below surface (mbs)) little or no positive herbicide detections were made. However, where the water table was at only 4-5 mbs, a regular pesticide signal of around 0.1 ug/l for isoproturon and chlorotoluron could be distinguished. Over the winter recharge period automatic borehole samplers revealed a series of short-lived peaks of isoproturon and chlorotoluron reaching up to 0.8 ug/l. This is consistent with a preferential flow mechanism operating at this particular part of the field. Such peaks were occurring over 2 years after the last application of these compounds. Shallow coring failed to uncover any significant pesticide pulse moving through the deep unsaturated zone matrix at the fieldsite.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/S0169-7722(01)00139-5
Programmes: BGS Programmes > Groundwater Management
CEH Programmes pre-2009 publications > Water
Additional Keywords: GroundwaterBGS, Groundwater, Pesticide pollution, Major aquifer
NORA Subject Terms: Hydrology
Related URLs:
Date made live: 23 Jul 2009 08:33
URI: http://nora.nerc.ac.uk/id/eprint/7773

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