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A new approach is presented in this paper for the dynamic modeling of the chemical and isotopic evolution of C1–3 during the hydrocarbon generation process. Based on systematic data obtained from published papers for the pyrolysis of various hydrocarbon sources (type I kerogen/source rock, type II kerogen/source rock, type III kerogen/source rock, crude oil, and asphalt, etc.), the empirical evolution framework of the chemical and isotopic composition of C1–3 during the hydrocarbon generation process was built. Although the empirical framework was built only by fitting a large amount of pyrolysis data, the chemical and isotopic composition of C1–3 derived from the pyrolysis experiments all follow evolution laws, convincing us that it is applicable to the thermal evolution process of various hydrocarbon sources. Based on the simplified formula of the isotopic composition of mixed natural gas at different maturities (δ13Cmixed), δ13Cmixed = X × n i A × δ 13 C i A + Y × n i B × δ 13 C i B X × n i A + Y × n i B , it can be derived that the cumulative isotopic composition of alkane generated in a certain maturity interval can be expressed by the integral of the product of the instantaneous isotopic composition and instantaneous yield at a certain maturity point, and then divided by the cumulative yield of alkane generated in the corresponding maturity interval. Thus, the cumulative isotopic composition (A(X)), cumulative yield (B(X)), instantaneous isotope (C(X)), and instantaneous yield (D(x)) in the dynamic model, comply with the following formula during the maturity interval of (X0~X). A(X) = ∫ X 0 X C X × D X d x B (X) , where A(X) and B(X) can be obtained by the fitting of pyrolysis data, and D(x) can also be obtained from the derivation of B(X). The dynamic model was applied on the pyrolysis data of Pingliang Shale to illustrate the quantitative evolution of the cumulative yield, instantaneous yield, cumulative isotope, and instantaneous isotope of C1–3 with increasing maturity. The dynamic model can quantify the yield of methane, ethane, and propane, as well as δ13C1, δ13C2, and δ13C3, respectively, during the hydrocarbon generation process. This model is of great significance for evaluating the natural gas resources of hydrocarbon source rock of different maturities and for identifying the origin and evolutionary process of hydrocarbons by chemical and isotopic data. Moreover, this model provides an approach to study the dynamic evolution of the isotope series of C1–3 (including reversed isotopic series), which is promising for revealing the mechanism responsible for isotopic reversal when combined with post-generation studies. [ABSTRACT FROM AUTHOR]

In recent years, lakes on the Qinghai–Tibet Plateau have become more responsive to climate change. In September 2011, Zonag Lake in Hoh Xil experienced sudden drainage, the water eventually flowed into Yanhu Lake, which caused Yanhu Lake to continue to expand. The potential collapse of Yanhu Lake could directly threaten the operational safety of the adjacent Qinghai–Tibet Highway, Qinghai–Tibet Railway. To explore the implications of expanding lakes on the surrounding permafrost, we selected Hoh Xil Yanhu Lake on the Qinghai–Tibet Plateau to study the effect of lake expansion on permafrost degradation. The permafrost degradation in the Yanhu Lake basin from October 2017 to December 2022 was inverted using Sentinel–1 satellite image data and small baseline subset interferometry synthetic aperture radar (SBAS–InSAR) technology. Additionally, permafrost degradation from February 2007 and February 2010 was analyzed using advanced land observing satellite phased array–type L–band synthetic aperture radar (ALOS PALSAR) satellite images and differential interferometric synthetic aperture radar (D–InSAR) technique. The results showed that the permafrost around Yanhu Lake experienced accelerated degradation. Prior to the expansion of Yanhu Lake, the average annual deformation rate along the line of sight (LOS) direction was 6.7 mm/yr. After the expansion, the rate increased to 20.9 mm/yr. The integration of spatial-temporal distribution maps of surface subsidence, Wudaoliang borehole geothermal data, meteorological data, Yanhu Lake surface area changes, and water level changes supports the assertion that the intensified permafrost degradation could be attributed to lake expansion rather than the rising air temperature. Furthermore, permafrost degradation around Yanhu Lake could impact vital infrastructure such as the adjacent Qinghai–Tibet Highway and Qinghai–Tibet Railway. [ABSTRACT FROM AUTHOR]

A zero-valent iron-loaded corn straw char (ZVI-CSC) was synthesized in this study for the remediation of As(V) and Cd(II) contamination. The impact of ZVI-CSC on the adsorption performance of As(V) and Cd(II) in solution, as well as their migration properties in soil, was investigated through adsorption kinetics and soil column leaching experiments, respectively. The results showed that the adsorption capacity of As(V) by ZVI-CSC was significantly improved to 14.42 g·kg−1 at pH = 3, compared with unmodified corn straw char (CSC). However, the adsorption capacity of Cd(II) was not improved. In the leaching experiments, the addition of ZVI-CSC to As(V)-contaminated soil resulted in a significant reduction of cumulative As(V) release rate from 32.26 to 3.11%, compared with corn straw char (CSC). Moreover, the role of ZVI in As(V)/Cd(II) remediation was analyzed. nZVI forms ≡Fe-OH and ≡Fe-OOH due to oxidation, which can form monodentate and bidentate complexes with As(V) via ligand exchange, thus promoting As immobilization. Furthermore, to further improve the adsorption performance of Cd(II), the electrostatic potential (ESP) of biochars with different surface functional groups (C = O, C–O–C, –OH, and –COOH) and their bond dissociation enthalpy (BDE) with As(V) and Cd(II) were calculated based on density functional theory (DFT). The results showed that –OH was the most effective for As(V) adsorption, and C–O–C was the most effective for Cd(II) adsorption. C = O and –COOH can be used to the simultaneous adsorption of As(V) and Cd(II). Therefore, the surface functional groups of ZVI-CSC can be selectively modified to improve its adsorption performance of As(V) and Cd(II). [ABSTRACT FROM AUTHOR]

The helium (He) contents of the Weiyuan and Anyue gas fields in the Sichuan Basin (China) differ significantly despite their similar helium‐nitrogen (N2) coupling characteristics, that is, the positive correlation between the N2 and He contents, and the negative correlation between the nitrogen/helium (N2/He) ratio and depth. To determine the factors influencing the differential enrichment of He resources and He–N2 coupling in the Weiyuan and Anyue gas fields, this study analysed the compositions of natural gases within the study area and established a computational model for evaluating the dissolution and exsolution amount of He and N2 in the pore water. The results indicated that: the uplift of the basement granite was crucial for the exsolution and enrichment of dissolved helium, and it was also the main reason for He–N2 coupling. The differential uplift that occurred in the Leshan–Longnvsi palaeo‐uplift during the Himalayan period further promoted the differential enrichment of He resources, thus also impacting the N2/He ratio in the study area. The distinct quantities of N2 and He exsolution during the uplift directly affected the negative correlation between the N2/He ratio and the depth. Within the same depth range of the uplift, the average and variations of the N2/He ratio in the crust‐derived helium‐rich natural gas reservoir were inversely proportional to the in situ molar partial pressure of He. The uplift of the crystalline basement is an important mechanism that causes the enrichment of helium resources and the coupling of helium‐nitrogen in the crust‐derived helium‐rich natural gas reservoir, which is of great significance for understanding the variation of N2/He ratio and exploration of He resources. [ABSTRACT FROM AUTHOR]

Background: The first local outbreak of Delta Variant B.1.617.2 COVID-19 of China occurred in Guangzhou city, south China, in May 2021. This study analyzed the transmission chains and local cluster characteristics of this outbreak, intended to provide information support for the development and adjustment of local prevention and control strategies. Methods: The transmission chains and local cluster characteristics of 161 local cases in the outbreak were described and analyzed. Incubation period, serial interval and generation time were calculated using the exact time of exposure and symptom onset date of the cases. The daily number of reported cases and the estimated generation time were used to estimate the effective reproduction number (Rt). Results: We identified 7 superspreading events who had more than 5 next generation cases and their infected cases infected 70.81%(114/161) of all the cases transmission. Dining and family exposure were the main transmission routes in the outbreak, with 29.19% exposed through dining and 32.30% exposed through family places. Through further analysis of the outbreak, the estimated mean incubation period was 4.22 (95%CI: 3.66–4.94) days, the estimated mean generation time was 2.60 (95%CI: 1.96–3.11) days, and the estimated Rt was 3.29 (95%CI: 2.25–5.07). Conclusions: Classification and dynamically adjusted prevention and control measures had been carried out according to analysis of transmission chains and epidemical risk levels, including promoting nucleic acid screening at different regions and different risk levels, dividing closed-off area, controlled area according to the risk of infection, raising the requirements of leaving Guangzhou. By the above control measures, Guangzhou effectively control the outbreak within 28 days without implementing a large-scale lockdown policy. [ABSTRACT FROM AUTHOR]