High-resolution paleoclimate data on stable isotopes in a stalagmite were coupled to glycerol dialkyl glycerol tetraethers (GDGTs). The Indian Summer Monsoon (ISM) transitioned from limited rainfall during the Last Glacial Maximum (LGM) to intense precipitation during early Holocene (22 to 6 ka). This was associated with changes in stalagmite growth, abundance of branched (br) and isoprenoid (iso) GDGTs, as well as δ¹⁸O, δ¹³C, Sr/Ca and GDGT-derived signals providing both temperature and moisture information. The reconstructed mean annual air temperature (MAAT) of the most modern stalagmite sample at ~19 °C, matches the surface and cave MAAT, but was ~4 °C lower during LGM. Warming at the end of LGM occurred before ISM strengthened and indicate 6 ka lag consistent with sea surface temperature records. The isotope records during the Younger Dryas show rapid progressions to dry conditions and weak monsoons, but these shifts are not coupled to TEX₈₆. Moreover, change to wetter and stronger ISM, along with warmer Holocene conditions are not continuous indicating a decoupling of local temperatures from ISM.

Osteoporosis is a chronic disease of public health importance, particularly in low and middle income countries. Measuring the bone mineral balance (BMB) in a non-invasive manner, and its response to different interventions, is critical to the definition of optimal strategies for its prevention and management. In this study, we demonstrate the usefulness of natural variability in calcium isotopes (δ^44/40Ca) of urine and the derived BMB estimates as a biomarker of bone health and its responsiveness to interventions. Vitamin D₃ is commonly used as a supplement for the prevention and treatment of osteoporosis, along with calcium supplements. We studied the effect of a short term vitamin D₃ supplementation on changes in urine δ^44/40Ca and the derived BMB. δ^44/40Ca before and after the vitamin D₃ supplementation yielded a statistically significant change (p = 0.050) with a positive δ^44/40Ca enrichment. The mean derived BMB was net positive (0.04 ± 0.05) in comparison to a net negative value for the control group (−0.03 ± 0.01). These results indicate the potential usefulness of urinary natural δ^44/40Ca and the derived BMB, which, along with bone mineral density could be used as a sensitive marker for precision in the prevention and treatment of osteoporosis.

The GasBench II peripheral along with MAT 253 combination provides a more sensitive platform for the determination of water isotope ratios. Here, we examined the role of adsorbed moisture within the gas chromatography (GC) column of the GasBench II on measurement uncertainties. The uncertainty in ¹⁸O/¹⁶O ratio measurements is determined by several factors, including the presence of water in the GC. The contamination of GC with water originating from samples as water vapour over a longer timeframe is a critical factor in determining the reproducibility of ¹⁸O/¹⁶O ratios in water samples. The shift in isotope ratios observed in the experiment under dry and wet conditions correlates strongly with the retention time of analyte CO₂, indicating the effect of accumulated moisture. Two possible methods to circumvent or minimise the effect of adsorbed water on isotope ratios are presented here. The proposed methodology includes either the regular baking of the GC column at a higher temperature (120 °C) after analysis of a batch of 32 sample entries or conducting the experiment at a low GC column temperature (22.5 °C). The effects of water contamination on long-term reproducibility of reference water, with and without baking protocol, have been described.