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Title: The Natural (Baseline) Quality Of Groundwaters In England And Wales. The Chalk Of The South Downs
Author: British Geological Survey (4)
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_748, Representation ID: 248, Object ID: 2074
This document forms one of the regional studies being carried out on representative aquifers or parts of aquifers in England and Wales to provide an improved understanding of the natural baseline quality of groundwaters. It serves as a reference document against which current water quality and future trends (improvements and deteriorations) may be assessed. Section I provides a brief summary of the water quality situation and in section II, further information is given concerning the controls on water quality necessary for an informed interpretation of the hydrogeochemical data. Representative analyses of groundwaters from pumped boreholes and springs in the South Downs area between Chichester and Lewes are used here as the basis for establishing the natural (baseline) water quality. These are compared with interstitial waters obtained from a deep borehole drilled at Sompting and from a shallow cored borehole drilled across the saline-freshwater interface near Lancing. With the exception of one site within the Chichester syncline, the chemical and isotopic characteristics show the water to be of low mineralisation, homogeneous and of recent origin and with chemistry which reflects the atmospheric inputs (Cl) as well as reactions at shallow depth between water and Chalk sediment. The waters are aerobic, although a small area of reducing groundwaters occurs beneath a confined section of the Chichester syncline. The South Downs groundwaters are less evolved compared with groundwaters in other regions in southern England. The water quality for the region is summarised in a Piper diagram and statistical summary. The influence of agricultural chemicals may be seen in around 30% of the boreholes but atrazine is detected in over 50% of the analyses, indicating the extent of human impacts on the region.
Publisher: Environment Agency
Subject Keywords: GroundwaterWater qualityBaseline surveysChalk streamsHydrologyPesticidesFreshwater ecology
Geographic Keywords: Sussex
Extent: 46
Total file downloads: 38

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