Boron Isotopes in the Mount Vulture Groundwaters (Southern Italy): Constraints for the Assessment of Natural and Anthropogenic Contaminant Sources

Figure 4

δ¹¹B (‰) versus B content (μg/l) binary plot. ML1 and ML2 curves indicate the mixing between local meteoric end-member (rainwater = RW, ; ) and range of isotopic values of the HSW group ( and −9.6‰; ). The MLA curve represents the hypothetical mixing behavior between local meteoric water and water-soluble anthropogenic boron compounds (synthetic Ca-borate fertilizers, average δ¹¹B value of -13.5‰ and , [21]). The MSA mixing curve is drawn with following data (RW, and sewage effluents with average δ¹¹B value of +2.6‰ and ; from Barth [43], Xue et al. [44], and Vengosh et al. [9]). Ranges of δ¹¹B of sewage effluents (−7.7‰ to +12.9‰; [9, 43, 44]), sodium perborates (–4.8‰ to +3.1‰; [2]), detergents (−2.9‰ to +3.1‰; [2]), synthetic Ca-borate fertilizers (–15‰ to –12.1‰; [21]), and manure (+6.9‰ to +42.1‰, [17, 44]) are shown for comparison.