Bath thermal springs

[Tom]

#An example from the south west of England, UK is the thermal springs of Bath. Here thermal water is believed to source from the Carboniferous and rise through faulted/fractured rocks of Triassic and Jurassic age (Gallois, 2007). It issues at the surface at around 46 deg C (Andrews et al., 1982).

#A number of boreholes intersect the various springs. In 2011/2012 one of these boreholes (installed in 1999) was decommissioned due to corrosion of the mild-steel casing. It has been speculated that the corrosion was in-part due to the groundwater composition, exacerbated by the high temperatures. The water rises through pyrite-bearing strata in the Lower Jurassic, sourcing sulfate.

#A summary composition for the King's Spring is given in the introductory document by Bath and North East Somerset (see references). pH and temperature data have been added from other sources (see below).

SOLUTION 1
units ppm
pH 7.0
temp 46.0
Na 195
Ca 358
Mg 57
Fe 0.6
Si 42
C(4) 193 as HCO3
S(6) 1015 as SO4
Cl 340

END

#Andrews et al (1982) give specific compositions including trace element concentrations for various studies. A script is shown below based on data for the King's Spring, determined in 1977-1979.

SOLUTION 2
units ppm
pH 6.68 #range 6.39-6.94
temp 46.5 #range 46.4-46.6 deg C
Na 183 #range 169-190
K 17.4 #range 16.2-20.3
Ca 382 #range 352-399
Mg 53 #range 52.0-55.4
C(4) 192 #range 184-206 as HC03
S(6) 1032 #range 1010-1060 as SO4
Cl 287 #range 280-292
Li 0.242 #range 0.24-0.255
Sr 5.92 #range 5.6-6.1
Ba 0.024
Mn 0.068 #total Mn, range 0.065-0.085)
Fe 0.879 #total Fe, range 0.95-1.32
Ni 0.022 #range 0.002-0.03
Cu(2) 0.0021 #range 0.0005-00037 as Cu2+
F 2.6 #range 2-2.2
Br 1.32 #range 1-1.5
N(5) 1.2 #range 0.9-1.7 as NO3-
P 0.02 #as HPO42-
Si 44.1 #range 43.2-44.3 as SiO2
-water 1 # kg

END


#Other data: O2 (mg/l) 0.5-6.0, Eh (mV) +220-32.
#Note you will need to use a database other than phreeqc.dat to consider nickel (e.g., wateq4f.dat).
#Note the output of SOLUTION 2 predicts saturation indices >0 for Fe2O3, FeOOH and Fe(OH)3, which may go some way to explaining why iron-rich deposits are commonly observed in the spring chamber.
#Notice the addition of trace element data in SOLUTION 2 improves the charge balance error compared to SOLUTION 1.



#References:

#Andrews, J.N., Burgess, W.G., Edmunds, W.M., Kay, R.L.F., and Lee, D.J. (1982). The Thermals Springs of Bath. Nature. 298, 393-394.

#Bath and North East Somerset Council. (2002?). The Hot Springs of Bath: Geology, geochemistry, geophysics: A review of knowledge relating to the Hot Springs of Bath, and summary of the research and investigations commissioned by the Bath Spa Project (Bath & North East Somerset Council), 1999 – 2002, as part of the Thermal Resources Project.

#Gallois, R. W. 2007. The formation of the hot springs at Bath Spa, U.K. Geol. Mag. Vol. 144, 741-747.