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The impact of urban groundwater upon surface water - eTheses ...

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Number <strong>of</strong> samples greater than detection limit<br />

50<br />

45<br />

40<br />

35<br />

30<br />

25<br />

20<br />

15<br />

10<br />

5<br />

0<br />

Trichloroethene (TCE)<br />

cis-1,2-Dichloroethene (DCE)<br />

Tetrachloroethene (PCE)<br />

Trichloromethane (TCM)<br />

1,1-Dichloroethane (DCA)<br />

1,1,1-Trichloroethane (TCA)<br />

Bromo-dichloromethane<br />

Vinyl Chloride<br />

1,1-Dichloroethene (DCE)<br />

trans-1,2-Dichloroethene (DCE)<br />

MTBE<br />

Total number <strong>of</strong> samples n=81 except for<br />

Vinyl Chloride for which n=16<br />

1,2-Dichloroethane (DCA)<br />

1,4-Dichlorobenzene<br />

Tetrachloromethane (CTC)<br />

Toluene<br />

1,2-Dichlorobenzene<br />

Benzene<br />

1,1,1,2-Tetrachloroethane<br />

Abstraction wells<br />

Shallow<br />

Riverbed<br />

Surface Water<br />

Figure 7.20 Frequency <strong>of</strong> VOC detection and mean concentrations in <strong>ground<strong>water</strong></strong> and <strong>surface</strong> <strong>water</strong> in the Tame Valley, 2001.<br />

(Analysed at the Environment Agency Laboratory in Leeds).<br />

1,1,2-Trichloroethane (TCA)<br />

Chlorobenzene<br />

Dichloromethane<br />

100.0<br />

10.0<br />

1.0<br />

0.1<br />

Mean Concentration μgl -1

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