Lincolnshire Limestone aquifer

Smalley P.C., Raiheim A., Dickson J. A.D. and Emery D. (1988) 87Sr/86Sr in waters from the Lincolnshire Limestone aquifer, England, and the potential of natural strontium isotopes as a tracer for a secondary recovery seawater injection process in oilfields. Applied Geochem. 3, 591-600. 

Fig. 11.27 Set of 14C data (pmc) marked on well locations in the Lincolnshire limestone aquifer. The arrow depicts the orginally suggested direction of ground-water flow. Dashed line marks discontinuity between phreatic (A) and confined (B) aquifers. (Data from Dowing et al., 1977.)...

Figure 11.15 Changes in Eh, pH, dissolved oxygen and HS" in the direction of ground-water flow in the Lincolnshire Limestone aquifer, U.K. Distances are measured from the outcrop area, which is oxidizing, to deeper, confined portions of the formation downdip, where the groundwater becomes anaerobic. After D. R. Champ and J. Gulens, Oxidation-reduction sequences in groundwater flow systems. Can. J. Earth Sci. 16 12-23. Copyright 1979 by NRC Research Press. Used by permission.

Elevated arsenic concentrations in oxic aquifers in Arizona (US) were linked to pH-dependent desorption (Robertson, 1989). Similar results exist for metamorphic aquifers in New England (US), where moderately alkaline waters (pH 7.5-9.3) were found to have elevated concentrations of arsenic (Robinson and Ayotte, 2006). Conversely, (BGS (British Geological Survey), 1989) suggested that arsenic concentrations of <4pgF-1 in water of the Lincolnshire Limestone (UK) cannot be explained by pH values of 7.0-9.5. McArthur et al. (2004) commented that the observations of pH increases with arsenic mobilization by Welch, Lico and Hughes (1988) and Robertson (1989) are not by themselves sufficient to prove that arsenic is mobilized by increasing pH. Arsenic may be mobilized by extended residence times, evaporation, and/or weathering, any of which could lead to both increases in pH and dissolved arsenic concentrations. 

The Lincolnshire limestone Jurassic aquifer in eastern England provides another insight into a phreatic-confined system. Isotopic data were reported (Dowing et al., 1977) from a number of wells in this system, located in the... 

---