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100 Chapter Three

Fig. 3.17 Graphical representation of
the modelled open- and closed-system
carbonate dissolution paths given in Table
3.5. Starting conditions are represented
by well samples contained in glacial till
deposits. The two fields showing Chalk
groundwaters represent saturated
conditions with respect to calcite with
the differences explained by the greater
dissolution of carbonate material at higher
Pco values in soils developed on the
2
carbonate and clay-rich till deposits. After
Hiscock (1993).

Table 3.5 Chemical models for the formation of Chalk groundwaters beneath glacial deposits in north Norfolk, eastern England, under
the processes of open- and closed-system dissolution of calcite. From Hiscock (1993).
−
2+
×
−1
−3
−1
−1
Well sample name CaCO added (× 10 mol L ) Ca (mg L ) HCO (mg L ) pH Pco (atmos) X calcite
2
3
3
Open-system conditions
Kelling Heath 0 10.0 56.7 6.62 1.94 −2.47
2.00 90.2 299.5 7.30 1.94 −0.03
Hindolveston 0 9.4 59.2 6.81 2.12 −2.09
1.75 79.5 271.5 7.44 2.12 0.02
Closed-system conditions
Kelling Heath 0 10.0 56.7 6.62 1.94 −2.47
0.70 36.0 130.5 8.02 3.00 −0.05
Hindolveston 0 9.4 59.2 6.81 2.12 −2.09
0.44 28.4 111.6 8.24 3.29 0.02