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Climate changes are known to have been a key regulator of the biodiversity in Earth's history. However, the dry‐humid degrees and alternating patterns throughout the Phanerozoic remain largely unconstrained. In this study, we report high contents (2.4 ± 3.8 mg N kg−1) and 17O anomalies (11.0 ± 7.4‰) of nitrate (NO3−) in the early Cambrian black shale from South China, likely caused by atmospheric NO3− intrusion under dry climates that followed tectonic uplift. By developing new methods to quantify aridity indices (AI, 0.06 ± 0.08) in combination with observational data with paleoclimate models, we reconstructed the historical AI variations. Our analyses revealed three significant dry‐to‐humid transitions which include Cambrian‐Ordovician to Silurian‐Permian, Permian‐Triassic boundary to middle Triassic‐early Jurassic, and Jurassic‐Paleogene to Neogene. This study quantitatively unlocked the Phanerozoic climate changes in South China, offering important evidence for understanding the co‐evolution of ecological and climatic systems in Earth's history. Plain Language Summary: Climate changes have played a critical role in shaping the biological evolution during the Phanerozoic, but the precise degree of dry‐humid fluctuations and their patterns remain unclear. This study observed high contents and 17O anomalies of nitrate in Cambrian black shale from South China, attributed to atmospheric deposition during dry periods following tectonic uplift. By integrating isotopic and sedimentological data with climate models, we quantified historical aridity and reconstructed its variations in South China. We identified three major dry‐to‐humid transitions in the Phanerozoic. These findings improve our understanding of how climate dynamics interacted with biological and geological changes. Key Points: High 17O anomaly (11.0 ± 7.4‰) of NO3− in Cambrian black shale was not explained by early diagenesis and modern surface processesA new framework using the ∆17O of sedimentary NO3− to quantify the deep‐time aridity was developedThe data suggest three alternations of dry‐humid climates in the Phanerozoic were recorded by sedimentary geochemistry in South China [ABSTRACT FROM AUTHOR]

Sheet-crack – primarily filled with chalcedony, quartz and calcite – is a type of significant sedimentary structure in almost all documented cap carbonates in platform-to-slope settings, which sharply overlie the global Marinoan (∼635 Ma) glacial tillite. The Jiulongwan section, located in the Yangtze Gorges areas, South China, is significant for the first discovery of extremely 13 C-depleted (δ 13 C down to −41‰) calcite cements in sheet-crack structure (Jiang et al., 2003a), which provides direct evidence for the methane seep hypothesis (Kennedy et al., 2001). Focusing on the calcite cements in the same section, Bristow et al. (2011) proposed a hydrothermal origin based on high temperatures (378 °C) determined by carbonate clumped isotope thermometry (CCIT). In this study, we provide evidence for the hydrothermal model using fluid inclusion technology (FIT) to quartz cements in the Jiulongwan section. The widespread sheet-crack structures in South China have uniform mineral paragenetic assemblages, which apparently reflect three stages of a hydrothermal fluid activity, including dolomitization at the early stage, silicification comprising chalcedony and quartz at the middle stage, and calcitization characterized by carbonaceous calcite filling preexisting voids at the late stage. Primary aqueous fluid inclusions from quartz crystals have homogenization temperatures of approximately 160–220 °C (mean, 192 °C, n = 31), while the salinity histogram contains two peaks at low salinity (6.3–8.3 wt.% NaCl equiv.) and high salinity (18.0–20.8 wt.% NaCl equiv.), reflecting precipitation caused by mixing of high- and low-salinity fluids. A modified and detailed hydrothermal model is proposed indicating that the sheet-crack structure resulted from successive thermal fluid activity after karstic dissolution due to postglacial isostatic rebound. This model is compatible with the unified sequence of glacio-eustatic events after the termination of Marinoan glaciation (Zhou et al., 2010) and the temperature results determined by CCIT (Bristow et al., 2011). [ABSTRACT FROM AUTHOR]

Purpose: This study was to estimate the impact of COVID-19 pandemic restrictions on sedentary behavior (SB) for Chinese university students during the pandemic period, as well as explore how sedentary behavior changed as a function of sex., Methods: We conducted an online questionnaire (the Sedentary Behavior Questionnaire) on students from one university in China during the pandemic period (March 29-April 15, 2020) and students retrospectively recalled pre-pandemic physical activity levels (before January 26, 2020). Sedentary behavior was measured using the short version of the Sedentary Behavior Questionnaire (SBQ). SB in a typical week during the COVID-19 pandemic period and before the COVID-19 pandemic restrictions were measured based on SBQ. The data was analyzed using a paired-samples t-test. Chi-square tests were to compare categorical variables., Results: A total of 1487 (947 males & 513 females; Age 19.72± 1.32yr., BMI = 21.12 ± 4.50) participated in this study. Before the COVID-19-associated lockdown restriction, on weekdays, survey participants averaged engaged in 11.41 (SD =3.93) hours of SB, 10.97 (SD = 3.85) hours of SB in males, 12.25 (SD =3.94) hours of SB in females; on weekends, survey participants averaged engaged in 13.18 (SD =4.06) hours of SB, 12.74 (SD = 3.96) hours of SB in males, 14.04 (SD =4.11) hours of SB in females. During the COVID-19-associated lockdown restriction, on weekdays, survey participants averaged engaged in 13.34 (SD =3.78) hours of SB, 12.90 (SD = 3.67) hours of SB in males, 14.19 (SD =3.83) hours of SB in females; on weekends, survey participants averaged engaged in 14.48 (SD =3.93) hours of SB, 14.10 (SD = 3.81) hours of SB in males, 15.22 (SD =4.04) hours of SB in females. Overall, on weekdays, The COVID-19-associated lockdown restriction on average appeared to increase SB by 1.93 (16.91%↑, 95% CI = 1.74, 2.12) hours, an increase in daily total SB by 1.92 (17.50%↑, 95% CI = 1.92, 2.15) hours for males, and an increase 1.94 (15.84%↑, 95% CI = 1.62, 2.27) hours in females. On weekends, The COVID-19-associated lockdown restriction on average appeared to increase SB by 1.30 (9.86%↑, 95% CI = 1.12, 1.48) hours, an increase in daily total SB by 1.36 (10.68%↑, 95% CI = 1.13, 1.58) hours for males, and an increase 1.18 (8.40%↑, 95% CI = 0.87, 1.50) hours in females., Conclusions: The COVID-19 restriction may lead to an increase in SB of Chinese university students. The total sedentary time of female students per week was higher than that of male students. Public policy action might be urgently needed to decrease the sedentary behavior of Chinese university students., Competing Interests: Conflict of Interest We have no conflict of interest to disclose at this time., (© JHEAL, 2022.)