The response of trees to climate is crucial for the health assessment and protection of forests in alpine regions. Based on samples of Pinus tabuliformis and Abies fargesii, two typical evergreen coniferous species with distinct elevation differences in the vertical vegetation zones of the Qinling Mountains, we have developed two tree-ring width chronologies for the southern slope of the central Qinling Mountains in central China. The correlation analysis results showed that the radial growth of P. tabuliformis and A. fargesii responded to different climatic factors. Water stress caused by temperature in May of the current year was the main limiting factor for radial growth of P. tabuliformis, while precipitation in September of the previous year and the current year had a negative impact on A. fargesii, with lag effects of temperature and precipitation during the previous growing season. Spatial correlation and comparative analysis indicated that the P. tabuliformis chronology responded to extreme dry and wet events on a regional scale. Interannual and multidecadal periodic signals recorded by tree rings suggested that the hydrological and climatic changes on the southern slope of the central Qinling Mountains were teleconnected with the Pacific and Atlantic Oceans, including El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation (NAO). Our results provide new evidence for a hydroclimatical response study inferred from tree rings on the southern slope of the central Qinling Mountains.

The Qinling Mountains in central China are rich in polymetallic mineralizations (e.g., Pb-Zn-Au deposits), and historic mining has resulted in large amounts of heavy metals being released into the environment. Thus, it is important to evaluate the ecological risk triggered by historic mining at this location. In this work, a gold mine was investigated as a case study to better understand the health risks present in the Qinling Mountains. To address this issue, a total of 84 soil samples and 23 surface water samples were collected from the gold mining district. Major and trace elements in soils, coupled with the pH and SO₄⁻² contents in water samples, were analyzed. The multivariate statistical analysis shows that human activities were found to have a significant impact on the levels of heavy metals (e.g., As, Hg, and Cd), pH, and SO₄⁻² in the soil within the study area, and the coefficient of variation for all indicators falls within a medium to high range (0.20–2.73). The maximum concentration of Cd can reach as high as 3005 mg·kg⁻¹. The spatial distribution of Cd and its isotope signatures indicate that sedimentation ponds and slag piles are the primary sources of high pollution within the study area, with heavy metal concentrations decreasing gradually as they disperse into the surrounding cultivated areas. The present study confirms that Cd and its isotopes can be directly used to track heavy metal sources over a large area (0.8 km²), and the conclusions drawn could be valuable for future restoration and management efforts. Simultaneously, this approach could offer a novel framework for the management of heavy metal contamination in soils at other metal mining sites.

Speleothem δ¹³C in monsoonal China differs from speleothem δ¹⁸O, which is widely used as a climatic proxy for several complex control reasons. Nevertheless, δ¹³C records have the potential to reveal the implications of hydroclimatic changes. This study reports a speleothem δ¹³C record from Didonghe (DDH) Cave in central China spanning 34 to 13 kyr BP. After we investigated the factors that influence speleothem δ¹³C, we found that the δ¹³C record showed that DDH Cave can prompt directional shifts via local hydroclimatic changes, such as in vegetation types, biomass, and rock–water interaction processes, suggesting that δ¹³C is mainly controlled by the local hydroclimate. Ensemble empirical mode decomposition (EEMD) results revealed a coupling relationship between δ¹⁸O and δ¹³C on multiple timescales, which suggested that changes in precipitation caused by large-scale monsoonal circulation are controlled by regional hydrological conditions to a great extent. However, the hydrological conditions of the cave were relatively mild and humid during the last glacial maximum (LGM), which revealed the impact of evaporation on changes in the region’s hydrological conditions. We also found that the δ¹⁸O and δ¹³C profiles decoupled when δ¹³C changed with a shift in the location of the westerly during HS1. The δ¹³C record correlates well with other paleoclimate records, suggesting that regional hydrological conditions are also modulated by the Earth’s internal and external driving factors.

Transboundary fossil-fuel CO₂ transport may affect regional atmospheric-background estimates, yet its isotope signal along China’s southwestern border remains poorly constrained. We analyzed annual tree-ring ∆¹⁴C records from one tree at each of two sites in Linzhi, southeastern Tibet. The 2014–2023 series provides one AMS determination per site-year (10 per site; 20 in total), but no within-site tree replication. AMS measurements were evaluated alongside HYSPLIT trajectory clustering and isotope mass-balance calculations. Mean Δ¹⁴C was 12.03‰ at Linzhi 1 and 14.86‰ at Linzhi 2. Across the nine years with background data (2015–2023), Type I South Asian terrestrial trajectory frequency was not significantly correlated with background deviation at Linzhi 1 (Spearman r_S = −0.18, p = 0.644) or Linzhi 2 (r_S = 0.30, p = 0.437). These nonsignificant associations, based on a short record and single-tree samples, do not establish that no relationship exists. Isotope mass balance estimated a fossil-fuel CO₂ contribution of approximately 2.8 ppm under the selected background and mass-balance assumptions; this is an approximate estimate, not a direct in situ measurement. HYSPLIT frequency indicates potential transport pathways, not transport intensity or the fossil-fuel CO₂ concentration of air masses. Linzhi 1 may be a candidate sentinel site, but this status requires validation with longer, replicated tree-ring records and continuous atmospheric observations.