Southwestern China Research Articles

An iteratively optimized downscaling method for city-scale air quality forecast emission inventory establishment

Air quality models (AQMs) are pivotal in forecasting air quality and shaping pollution control strategies. Nonetheless, the effectiveness of AQMs is often compromised in many cities due to the absence of accurate local emission inventories. To address this gap, this study presents a novel AQM-ready emission inventory generation technique with iterative optimization ability for city-scale applications in China. An efficient emission processing tool was introduced in this study, which utilizes the High-Resolution Multi-resolution Emission Inventory for China (HR-MEIC) as input. Using environmental observations and a region map, the tool can justify emissions of different regions iteratively. With the iterative optimization method, the model performance can be notably improved even without local emissions. The optimization was realized by splitting model-ready emissions into different regions and adjusting the emissions using scale factors calculated with the modeling results and the observations of each region. This methodology was applied to the Eight Cities in the Chengdu Plain (CP8C), located in the western margin of Sichuan Basin with complex topography and meteorological conditions, southwestern China, monthly throughout 2023. Air quality modeling was carried out using Weather Forecast and Research Model (WRF) and the Community Multiscale Air Quality Model (CMAQ). The results showed that the optimization acquired a good performance after five cycles for PM2.5 and NO2, with correlation coefficients (R values) surging from 0.62 and 0.37 to 0.77 and 0.73, respectively, while their normalized mean bias (NMB) substantially decreased from 22.8 % and 100.4 % to 3.6 % and 3.3 %. The underestimation on O3 concentration was also improved by the optimization, although enhancements in O3 modeling remained modest. This technique provides an easy-to-copy method to generate reasonable AQM-ready emission files with open emission data and observation data, which would be beneficial for the cities' air quality forecast in cities without local emission inventories.

Inherent carbon burial potential of lakes across China

Eutrophication is one of the most important factors for the increasing production of organic carbon in inland waters. Variations in primary productivity across lakes due to eutrophication complicate predictions regarding future carbon burial and management of carbon sequestration in lakes. Phosphorus, an essential nutrient for plants and notorious for eutrophication, often limits primary productivity in lakes. It is crucial to normalize organic carbon burial to the content of total phosphorus (TP) in the water column to compare the inherent carbon burial capacity across lakes. However, the absence of long-term observational data of TP in lake water columns has hindered the ability to do so. In this study, we first verified that TP in sediments of Chinese lakes could substitute for that in the water column to reflect the annual primary productivity of lakes. Then we defined the inherent carbon burial potential of lakes as the total organic carbon to TP atomic ratio (TOC/TP) in the sediments. We quantified the inherent carbon burial potential of 90 lakes across China, exploring its spatial distribution, temporal trends, and potential controlling factors. The inherent carbon burial potential, based on surface sediments, decreased from western to eastern China, ranging from 466.1 to 24.3 with a mean of 137.0 ± 87.4. Mean annual precipitation was negatively related, while mean lake depth was positively related to the inherent carbon burial potential of the lakes across China. Analysis of sediment cores revealed that the mean inherent carbon burial potential of the lakes across China increased from 75.1 to 122.9 since the 1950s. Inherent carbon burial potential of the lakes in southwestern and eastern China, however, decreased since the 1990s. Changes in the extent of cultivated land in the watersheds were positively related to variations in the inherent carbon burial potential of Chinese lakes in the past few decades.

Comprehensive analysis of NGS-based expanded carrier screening and follow-up in southern and southwestern China: results from 3024 Chinese individuals.

This study aimed to screen southern and southwestern Chinese individuals using expanded carrier screening (ECS), which explores the carrier status of recessively inherited diseases in southern and southwestern China, evaluates the clinical effectiveness of ECS application, and helps recognize high-risk fetuses that may have genetic disorders early in pregnancy, to provide better reproductive guidance. ECS for 220 diseases based on next-generation sequencing was performed on 3024 southern and southwestern Chinese individuals (1512 couples). Carrier status was analyzed; genes and loci with high frequencies of variants and on high-risk couples (ARCs) were focused to evaluate the clinical utility of our ECS technology and provide them precise fertility guidance. In total, Pathogenic/likely pathogenic(P/LP) variants were found in 1885 individuals, so the carrier frequency was 62.3%, and 23.2% of the individuals were carriers of multiple diseases. furthermore, 2837 variants were detected, and the average number of P/LP variants carried per subject was 0.938. Additionally, 128 ARCs carried P/LP variants of the same gene, and the theoretical incidence rate in their offspring was as high as 2.12%. This study validated the application of our ECS technique for carrier screening in southern China, identifying carrier status and providing accurate carrier frequencies for hundreds of genetic diseases.

Characteristic analysis of India-Burma trough events and its impact on winter precipitation in South and East Asia: Based on objective identification

Abstract During the boreal winter, the India-Burma trough (IBT), a shortwave trough system primarily positioned over the northern Bay of Bengal, exerts a significant synoptic scale variation and impact on precipitation in South and East Asia. This study utilizes the 6-hourly ERA5 dataset to objectively identify and track 714 IBT events from 1981 to 2019. On average, IBT occurred about 54.7 days per year, with an average of 18.3 events annually and lasting around 2.5 days. IBT events are classified into two types: local and eastward-moving. Local IBTs manifest in the middle and lower troposphere with a vertical temperature structure of warm-over-cold, whereas the signals of the eastward-moving IBTs extend from the lower to the upper troposphere, exhibiting cold anomalies vertically. The impacts on winter precipitation in South and East Asia differ significantly between these two IBT types. Local IBTs are primarily linked with the eastward propagation of wave disturbances along the subtropical westerly jet, while eastward-moving IBTs are associated with robust disturbance sources from mid-high latitudes and jointly modulated by the consequent eastward propagation of Rossby wave trains along northern and southern branches of the westerly jet streams. Precipitation anomalies during local IBTs are typically positive (negative) in the Indochina Peninsula and southwestern China (Indian Peninsula), whereas eastward-moving IBTs correlate with more intense and widespread precipitation in South and East Asia, with a pronounced band of anomalies from the Indochina Peninsula to southern China.

Scenario Simulation and Efficiency Study of Hydropower Development to Promote Regional Sustainable Development: An Empirical Analysis of a Province in Southwestern China

Hydropower is a significant component of China’s contemporary energy framework, with its construction and operation critically contributing to the advancement of sustainable development in the region. However, the influence of hydropower development on regional sustainable development is not evident, and the course of its effect is not clear. In this work, on the basis of assessing the effect of hydropower development on regional sustainable development, a system dynamics (SD) simulation model was created, and 15 distinct development modes were set and tested. The relative driving efficiency of hydropower growth on sustainable development in a province in Southwest China under several scenarios was assessed using the super-efficiency-slacks-based measurement (Super-SBM), and an efficiency analysis was undertaken. The study’s findings demonstrate that: (1) Hydropower development had a complex driving influence on sustainable development in the province in 2015–2022. (2) The relative driving efficiency of the province over the study period exhibited a changing pattern and was at a high level greater than 0.7. (3) New hydropower investment and hydropower generation are the major factors impacting the relative driving efficiency of hydropower development on regional sustainable development in the province. The study’s findings provide a platform and reference for supporting regional sustainable development through hydropower development.

Selection of the minimum data set and quantitative soil quality indices for different azalea forest communities in southwestern China

Selection of the minimum data set and quantitative soil quality indices for different azalea forest communities in southwestern China

Environmental changes and human impacts over the past 1200 years: Evidence from high-resolution pollen records from peat in the Yunnan-Guizhou Plateau, Southwest China

Over the past millennium, the understanding of vegetation and climate changes in mountainous regions, driven by both natural and anthropogenic forces, remains unclear. In this study, we provide a high-resolution vegetation record spanning the past 1200 years from a subalpine peatland in the Niangniang Mountains, southwestern China. By analyzing pollen, charcoal, and loss-on-ignition from the peat sediment, we elucidate the interactions between vegetation, fire, and human impact. Our findings reveal that before 1150 CE, the mountains were covered with dense broadleaf forests and experienced minimal human activity. Natural forcings, primarily climatic conditions, drove vegetation succession and forest fires. After 1150 CE, the Human Influence Index (HII) increased sharply, coinciding with a rise in cereal-type pollen. Significant agricultural activities in the southwestern mountainous regions of China began after 1150 CE, which is later than those in the low-altitude lake basins of southwestern China. During the Medieval Climate Anomaly (MCA, 836–1400 CE), the Niangniang Mountains were characterized by warm and humid climatic conditions, a stable forested landscape, and a high peat carbon accumulation rate. Although human activities increased markedly during this period, the arbors did not undergo notable changes, and climate forcings continued to have a greater impact on vegetation than anthropogenic forcings. During the Little Ice Age (LIA, 1400–1900 CE), the regional vegetation landscape transitioned from dense forests to open grasslands as climate conditions became cold and dry, reducing peat carbon accumulation rate. This period also saw increased forest fires and significant human-driven deforestation, with anthropogenic forcings becoming dominant. After 1900 CE, vegetation changes were increasingly influenced by government policies. Comparison with major climate forcings and spectrum analysis have shown that variations in monsoon intensity, regulated by solar and volcanic activity, have influenced the climate and peat depositional environment in the Niangniang Mountains. Our research offers meaningful insights into forest conservation in the mountainous regions of the Yunnan-Guizhou Plateau.

Nonlinear Seismic Response of an Alluvial Basin Modelled by Spectral Element Method: Implementation of a Davidenkov Constitutive Model

ABSTRACT A subroutine incorporating soil nonlinearity is presented using SPECFEM3D Cartesian, an open-access Spectral Element Method (SEM)-based code for full waveform simulation. Specifically, the adaptive time-stepping scheme is developed in the time marching algorithm, enabling the computation to be effective. The verification of the method is first demonstrated via comparison with results calculated by DEEPSOIL. Then, applications for a trapezoid basin are implemented to study the effects of impedance ratio (IR), magnitude, and basin shape on ground motion. Finally, we focus on the nonlinear ground motion simulation of the Shidian basin in southwestern China and compare it with the linear results.

Spatiotemporal distribution of pCO2 and CO2 flux and the regulatory factors: From the perspective of a subtropical canyon-shaped reservoir, southwest China

Reservoir carbon cycling is a critical component of the global carbon cycle, particularly in subtropical canyon-shaped reservoirs where unique geomorphological features and hydrological regulation under monsoon climate provide a distinct perspective for carbon cycle research. This study takes the Zipingpu Reservoir (ZPPR) in southwestern China as an example and reveals significant seasonal variations in partial pressure of carbon dioxide (pCO2) and carbon dioxide flux at the water-air interface (FCO2) through annual monitoring. The average pCO2 in ZPPR is 486 μatm, and the average FCO2 is 0.093 g C m-2d-1, with approximately 42.4 % of FCO2 measurements being negative, indicating the reservoir's role can act as a carbon sink. The study also estimated the gas transfer coefficient (K), with an average value of 1.888 md-1. Peak FCO2 during spring and summer is three times higher than in other seasons, consistent with the main influencing factors of inflow dynamics, metabolic processes, and reservoir operation strategies. Inflow and operational activities, particularly during spring and summer, drive CO2 emissions in the downstream reach and upstream tributary, while biological activity facilitates CO2 uptake in the lacustrine area and forebay tributary, with enhanced absorption occurring in the autumn. Concurrently, high-intensity FCO2 emissions from the upstream river section during summer underscore the importance of carbon emission monitoring and management during critical periods. The findings not only enhance the understanding of FCO2 assessment accuracy but also provide a framework for evaluating and optimizing carbon dynamics management strategies in canyon-shaped reservoirs, contributing valuable insights to global carbon cycle research.

Contemporary crustal strain rates derived from GPS measurements in southwestern China

Surface strain rates in southwestern China can provide constraints on tectonic evolution of the Tibetan Plateau. Unfortunately, different strain rate fields were obtained from different authors although almost the same GPS data were exploited. Based on updated GPS data, in this paper, we calculate the strain rates in southwestern China using the method proposed by Zhu et al. (2005, 2006). The results confirm that the strain rates in the Sichuan Basin and the South China Block are very small, and the high values are largely concentrated along the Xianshuihe-Anninghe-Xiaojiang fault system and the Sagaing Fault. Furthermore, the highest principal strain rates are located around the eastern Himalayan syntaxis (EHS), with compressive orientations perpendicular to the strike of the Main Thrust Belt. The basic characteristic of the strain rate distribution is in accordance with the tectonic structures from the geological and geophysical investigations. In particular, the two calculated extensive deformation regions basically match the locations of normal-faulting earthquakes in the Sichuan-Yunnan Rhombic Block (SYRB), with one in N-S extension trending in the northern SYRB, and the other nearly E-W orientation in the southern SYRB. We suggest that the extensive deformation and the normal faulting earthquakes in southwestern China is mainly controlled by the lower crustal channel flow with a bend direction, rather than by gravitational spreading alone, as previous authors proposed.

Morphological and Phylogenetic Analysis Reveals Two New National Records of Viola (Violaceae) from Southwestern China

Two rarely reported violets, Viola annamensis Baker f. and V. rheophila Okamoto were confirmed as new additions to the flora of China, based on three collections from Yunnan and Guangxi, southwestern China. Molecular phylogeny analysis based on nrITS dataset was conducted to facilitate further identification and their phylogenetic position. A brief description of the two new recorded species were also presented.

Relationships between pollen assemblages and modern vegetation of the southern Gaoligong Mountains region, southwest China

Comprehensive understanding of the modern pollen–vegetation relationship is crucial for utilizing fossil pollen to reconstruct palaeovegetation, especially in mountainous areas of southwestern China. In this study, we present forty-five modern surface samples collected from five different vegetation communities of the southern Gaoligong Mountains region, and the vegetation composition was investigated at each sample site. The modern pollen assemblages were analyzed through multivariate analysis to evaluate the relationships between vegetation types and pollen assemblages, and to investigate the representation of major pollen types in different vegetation types. The results indicate that the surface pollen assemblages of different vegetation types reliably represent the modern vegetation. The median R-values of dominant pollen taxa in the Gaoligong Mountains region can be ordered as follows: Pinus > Alnus > Poaceae > evergreen Quercus. The over-representation of Pinus pollen, attributed to its high productivity and strong dispersal ability, makes it the dominant component of exotic pollen. Conversely, the under-representation of evergreen Quercus suggests that the presence of its pollen within a sample might indicate the growth of the local parent plant in the study area. The human activities in the region have a recognizable effect on the surface pollen spectra and also exert a significant negative impact on pollen diversity. Our study supplements the modern pollen database of the mountain regions in southwestern China, and provides representative modern pollen analogues to interpret fossil pollen records from southwestern China and similar regions.

Sedimentary antimony stable isotope record of anthropogenic contamination in a karst lake in southwestern China

Anthropogenic sources of antimony (Sb) are an important driver of pollution in the Earth environment, but their roles in the historical changes of Sb pollution in lake ecosystems are currently poorly understood. This study documents the sedimentary Sb deposition fluxes in Hongfeng lake (HFL), in southwestern China during 1958–2021 and quantifies the changes of anthropogenic contributions to sediments using Sb stable isotopes. Mean Sb concentration (mean: 1.89 mg kg−1) and deposition flux (mean: 302.1 ng cm−2 a−1) in lake sediments remained relatively stable from 1958 to 1980. Sb deposition fluxes increased rapidly since 1980, peaked at 990.8 ng cm−2 a−1 in 2000, and then decreased consistently, reaching 306.9 ng cm−2 a−1 in 2021. Generally, the historical changes in Sb isotopes were anticorrelated with Sb deposition fluxes and enrichment factors, suggesting a lower ε123Sb signature in anthropogenic loading sources, and highlight the ability of Sb isotopes to distinguish anthropogenic signatures from natural processes in complex hydrological systems. Using a binary end-member mixing model, the contributions of anthropogenic sources to the accumulated of Sb in the lake sediments were estimated to be 20 % before 1980s and increased approximate 58 % during 2000–2015, then decreased to 24 % in 2021, likely reflecting the changes of degree in regional industrial activities. Our results help to better understand the response of Sb pollutions to anthropogenic activities and would in turn benefit the controls Sb contamination in lake ecosystems.

Spectrum of DNA variants for patients with hearing loss in 4 language families of 15 ethnicities from Southwestern China

Hearing loss is a common disease. More than 100 genes have been reported to be associated with hereditary hearing loss. However, the distribution of these genes and their variants across diverse populations remains unclear. In this study, we gathered 347 hearing-impaired patients from four language families (Sinitic, Tibeto-Burman, Kra-Dai, and Hmong-Mien) in Southwestern China, excluding cases caused by common mutations in the GJB2 gene. By using next generation sequencing, 122 genes associated with hereditary hearing loss were analyzed on these patients. Rare candidate variants were identified in 71.93 % (264/347) of patients with hearing loss. The diagnostic rate varied around 10 % across different language families. The most frequently identified causative genes in successfully diagnosed cases were SLC26A4, MYO7A and TMPRSS3. Moreover, a substantial number of variants of unknown significance (VUS) were identified in our patient cohort. This underscores the critical need for establishing ethnicity-specific genomic databases for hearing loss. It will significantly improve the clinical diagnostic rate for hearing loss in this region.

Cadmium Distribution and Bioavailability in Paddy Soil Profiles from Regions Impacted by High Geochemical Background and Mining Activities, <?A3B2 pi6?>Southwestern China

Cadmium Distribution and Bioavailability in Paddy Soil Profiles from Regions Impacted by High Geochemical Background and Mining Activities, <?A3B2 pi6?>Southwestern China

Response of Leaf Traits and Photosynthetic Fluorescence Characteristics of Fraxinus malacophylla Seedlings to Rainfall Patterns During Dry and Rainy Seasons in Southwestern China.

Global climate change has led to a shift in rainfall patterns. And as water is an essential ingredient for plant photosynthesis, shifts in rainfall patterns will inevitably affect plant growth. This study was conducted in Kunming, southwest China. In this study, the response of leaf traits and photosynthetic fluorescence properties of Fraxinus malacophylla seedlings to rainfall patterns during the dry and rainy seasons was investigated using a natural rainfall interval of 5 days (T) and an extended rainfall interval of 10 days (T+) as rainfall interval treatments and a monthly average rainfall as a control (W), with the corresponding rainfall treatments of a 40% increase in rainfall (W+) and a 40% decrease in rainfall (W-). The results showed that Pn, Gs, and Tr basically all tended to increase and then decrease with increasing rainfall in the dry season and generally reached the highest under the W treatment; Pn, Gs, Ci, and Tr mostly remained high at 5 days relative to 10 days; PI was overall higher under the W treatment throughout the dry season. Extending the rainfall interval at the beginning of the rainy season significantly reduced Fm; throughout the rainy season, Gs, Ci, and Tr basically showed a decreasing trend with increasing rainfall, reaching the highest under the W-treatment and mostly higher at 5 days than at 10 days. These results suggest that natural rainfall intervals and natural rainfall amounts are more favorable to the growth of Fraxinus malacophylla seedlings in the dry season; reduced rainfall and multiple rainfalls in the rainy season tend to promote photosynthesis in Fraxinus malacophylla. This study reflects the different survival strategies of Fraxinus malacophylla under different rainfall patterns, as well as provides a theoretical basis for understanding how Fraxinus malacophylla can grow better under rainfall variability and for future management.

Predicting the Potential Distribution of Rare and Endangered Emmenopterys henryi in China Under ClimateChange.

Climate change has a pivotal impact on the potential distribution of endangered and relic tree species. Probably due to unrepresentative sampling and single algorithm, at present, there are different views on the potential range of the endangered tree Emmenopterys henryi, endemic to China. Here, we first collated 612 occurrence records and 22 environmental variables including climate, topography, and soil. Combined the Biomod2 with MaxEnt, we then predicted its past, current, and future potential suitable area in China, and determined the key factors influencing its distribution. The ensemble model results showed that the main environmental variables affecting this species were the minimum temperature of the coldest month (BIO6), precipitation of warmest quarter (BIO18), and temperature seasonality (BIO4). Its current potential distribution area was 176.53 × 104 km2, mainly concentrated in eastern, central, and southwestern China. Collectively, the suitable area of E. henryi would averagely decrease by 3.90% in all 16 future scenarios, with its centroid largely migrating northeastward. Our findings indicate that the endangered E. henryi covered 18 provinces in China, having a larger area than known. Moreover, climate change may have an adverse effect on its potential distribution. In addition, the ensemble model can produce more effective prediction outcomes than MaxEnt for such endemic tree species with large environmental range. We recommend increasing sample representativeness by analyzing the completeness properties of sample coverage, and simultaneously selecting appropriate algorithms to ensure the reliability of distribution prediction for endangered and relict tree species.

Sulfide trace element enrichments in the metamorphic basement-hosted Xinhua Pb-Zn-Cu vein-type deposit, eastern Guizhou province (SW China)

Cambrian carbonate formations are widespread in the western Hunan-eastern Guizhou (WHEG) region (southwestern China), which hosts many Mississippi Valley-Type (MVT) lead–zinc (Pb-Zn) deposits. Regional Pb-Zn mineralization is well developed in the low-grade metamorphic rocks of the basal Proterozoic Banxi Group. The mineralization is associated with quartz veins and generally distributed along NE-trending fault zones. Moreover, these deposits have an extensive distribution and high grade, and are associated with Cu-Ag endowment. However, geological and geochemical research on these Pb-Zn vein-type deposits is relatively limited, and their relationship with the regional MVT mineralization remains unclear. The representative Xinhua deposit in Danzhai district is selected as the study subject. We conducted in situ trace element analyses on the sphalerite and chalcopyrite from the various metallogenic stages, and compared them with published sphalerite trace element data from the MVT Pb-Zn deposits in the western Hunan-eastern Guizhou metallogenic belt. Seven orebodies in Xinhua Pb-Zn deposit have been discovered so far, with a metal resource of over 120,000 metric tonnes of Zn + Pb. Field geology and microscopic petrography have revealed two mineralization stages: An early-stage black sphalerite (Sp-I) followed by reddish-brown sphalerite (Sp-II) mineralization, which corresponds to the main chalcopyrite mineralization stage, and a later-stage light-yellow sphalerite (Sp-III), Cu ore-barren mineralization.LA-ICPMS data indicate that the sphalerite from Xinhua has similar trace element compositions to those from the MVT Pb-Zn deposits in the region. They are relatively enriched in Ga, Cd, and Ge, while depleted in Fe, Co, and Mn. Critical metal Ge and Ga are particularly enriched in sphalerite, especially in Sp-I (Ge max 937 ppm, Ga max 824 ppm). The substitution mechanism of Ge and Ga in sphalerite are likely 2Cu+ + Ge4+ ↔ 3Zn2+ and Cu+ + Ga3+ ↔ 2Zn2+. Indium and Sn are mainly present in Sp-I and Sp-III. Chalcopyrite contains Zn and Sn both exceeding 100 ppm. Contents of Se, Ag, In, and Sn in chalcopyrite are significantly higher than those in sphalerite. Calculation of the sphalerite trace element geothermometer (GGIMFis) suggests that the average sphalerite ore-forming temperatures are 164 °C (Sp-I), 156 °C (Sp-II), and 205 °C (Sp-III), implying medium- to low-temperature mineralization. This indicates a possible influx of high-temperature, in-bearing fluid during the late-stage mineralization.In summary, the faults-controlled vein-type Pb-Zn deposits (e.g., Xinhua) may have been products of the same Kwangsian orogeny as other strata bound MVT deposits, and the Xinhua deposit features two mineralization stages with multiple ore metal sources. During the ore-forming fluid ascent, some ore-forming materials may have precipitated in the fluid conduits. And exposed after the erosion of the shallower stratiform orebodies and strata. Consequently, the Xinhua Pb-Zn deposit represents the preserved ore-fluid conduit phase (in the basement strata) of the MVT mineralization.

Pyrite trace metal and sulfur isotopic compositions track metalliferous fluid circulation within the Ordovician/Silurian organic-rich black shales in the eastern Sichuan Basin, southwestern China

Depicting metalliferous fluid flows in sedimentary basins has a remarkable implication for understanding the formation and evolution of organic-rich sediments. The Middle-Upper Yangtze region in South China hosts voluminous gaseous hydrocarbons and MVT-type ZnPb deposits. Natural gases are mainly distributed in the Sichuan Basin, yet ZnPb deposits are found in surrounding regions of the basin. Such a unique distribution pattern implies that the interplay between metalliferous fluids and organic-rich sediments may be extensive in the boundary of these two types of deposits. A typical Ordovician/Silurian (Wufeng/Longmaxi formations) organic-rich black shale outcrop occurs in the eastern boundary of the Sichuan Basin. Pyrites are frequently distributed across this section, providing an ideal opportunity to investigate features of metalliferous fluids and their potential impacts on organic-rich sediments. Pyrites associated with high-angle carbonate veinlets are recognized in the studied area, and this group of pyrites (“Group 2”) commonly display planar-laminated morphologies, moderate δ34S values (0.78 ‰–8.86 ‰), and elevated trace metal contents (Ni, Pb, Mn, Mo, Tl, and REE) than those not associated with carbonate veinlets. These features suggest that this group of pyrites may be precipitated via local metalliferous fluid flows. Besides, pyrites with relatively lower trace metal contents can be further divided into two groups, including a group of euhedral/subhedral pyrites with more depleted δ34S values (−18.06 ‰ – -1.15 ‰; “Group 1”) and a group of planar-laminated/cubic pyrites with enriched δ34S values (10.55 ‰–37.62 ‰; “Group 3”). Pyrites of Group 1 and Group 3 may be formed via bacterial sulfate reduction (BSR) and thermochemical sulfate reduction (TSR), respectively. The discovery of fluid-related, trace-metal-enriched pyrites implies that fluid circulation within organic-rich black shales has the potential to remobilize, transport, and re-deposit trace metals. Besides, metalliferous fluid may also promote organic matter maturation within the Sichuan Basin. The outcomes of this study, combined with previous findings of metalliferous fluid flows in the center of the basin and ZnPb mineralization belts surrounding the basin, imply that a widespread Ediacaran-Palaeozoic fluid circulation system may exist in the Middle-Upper Yangtze region.

A Comprehensive Quality Evaluation for Gentiana rigescens Franch.by Fingerprinting Combined with Chemometrics and Network Pharmacology.

Gentiana rigescens Franch. (G. rigescens) is a unique traditional medicinal herb from southwestern China, and its clinical mechanism for the treatment of hepatitis and the quality differences between different origins are not clear. The research aims to analyze the mechanisms for the treatment of hepatitis and differences in inter-origin differences using analytical techniques, chemometrics, and network pharmacology. Through infrared spectroscopy, spectral images, and high-performance liquid chromatography (HPLC) analysis, it was found that there were differences in absorbance intensity and significant differences in compound content among the samples'origin. G. rigescens iridoids and flavonoids exert therapeutic effects on hepatitis through multiple targets and multiple pathways. The above HPLC, chemometrics, and network pharmacology results revealed that gentiopicroside, and swertiamarine was the best quality marker among origins. The ResNet model could be utilized as an effective tool for tracing G. rigescens's origins. The PLSRmodel had excellent predictive performance in determining the content of gentiopicroside and swertiamarine, and could quickly, accurately, and effectively predict these two compounds. The research investigates the differences in G. rigescens origins from multiple perspectives, establishes image recognition models and prediction models, and provides new methods and theoretical basis for quality control of G. rigescens.