Origin and evolution of waters in the Hancheng coal seams, the Ordos Basin, as revealed from water chemistry and isotope (H, O, 129I) analyses

Rapid determination of 129I in large-volume water samples using rotary evaporation preconcentration and accelerator mass spectrometry measurement

“…These results are in good agreement with those published in our previous work [19,20,37], indicating that the rotary evaporation method is accurate, time saving and suitable for 129 I analysis of large-volume environmental water samples. [37] Rain Xi'an 1 1000 100 1.2 93.3±1.3 24.5±2.5 24.6±2.1 [37] Lake water Xi'an 1000 100 1.2 93.4±1.5 5.68±0.28 5.74±0.32…”

“…Direct evaporation at sub-boiling conditions is conventionally used, giving a high iodine recovery (>90%) but also taking a long time. For instance, it takes more than 20 h to concentrate a water sample from 5 L to 1 L [19,20]. Rotary evaporation method is operated under pressure for continuous washed using deionized water, and the separated AgI was dried at 60℃ for 2-3 h. After ground to fine powder, 3 times (by weight) niobium powder was weight and mixed with the AgI powder, the mixture was pressed into a copper holder for the AMS measurement of 129 I/ 127 I ratio.…”

“…Ground water Hancheng 1 5000 100 5 89.0±2.4 0.10±0.05 0.11±0.04 [20] Rain Xi'an 2 700-1500 100-300 10-12 91.7-99.5 -- [19] Ground water Hancheng 2 5000 1000 > 20 92.0-99.9 -- [20] * Methods: 1. Rotary evaporation followed with solvent extraction; 257 2.…”

Geological conditions of coalbed methane accumulation in the Hancheng area, southeastern Ordos Basin, China: Implications for coalbed methane high-yield potential

“…(a) fracture pressure versus depth, (b) closure pressure versus depth, (c) permeability versus depth, (d) reservoir pressure versus depth, and (e) 129 I/ 127 I versus depth. Notes: the data in (a) and (b) are from Li et al., 2017; the data in (c) are from Liu, 2016; the data in (d) are from Yi et al., 2017; and the data in (e) are from Ma et al., 2013.…”

“…The 129 I/ 127 I ratio is higher above 800 m, suggesting that meteoric-derived water is extensively recharged and mixed with the initial formation water. The meteoric-derived water mixing has less impact on the deeper samples below 800 m (Ma et al., 2013).…”