Although it is instructive to normalize REE concentrations of the groundwater in this study to PAAS for purposes of comparison with earlier studies, it is more appropriate to normalize these groundwater to the REE concentrations of the limestones in this study because aquifer rocks are thought to be the chief source
of REEs to groundwater . Figure 6 shows a plot of REE concentrations of LW-normalized to the average limestones from Table 4. The average limestone
normalized groundwater patterns are similar to the PAAS normalized patterns with little differences. For example,the groundwater also exhibits HREEs enrichment relative to LREEs with NdRN/YbRN=0.26−0.53 , and shows weak to no Ce anomalies.Additionally, the Eu/Eu*RN ranges from 0.55 to 1.30 with average of 0.85. It is worth noting that the fractionation of REEs of groundwater normalized to
PAAS and average limestone are different (e.g. thefractionation of La-Nd relative to Gd-Er is more obvious in PAAS normalized REE patterns than average
limestone normalized, with average NdSN/GdSN of 0.56 whereas NdRN/GdRN of 0.78).