Areas Of Southwest China Research Articles

Temporal Changes in Land Use, Vegetation, and Productivity in Southwest China

In recent decades, vegetation coverage and land use/land cover (LULC) have constantly changed, especially in southwest China. Therefore, it is necessary to conduct in-depth research into the temporal–spatial variation patterns of vegetation greening, LULC, and gross primary productivity (GPP). Here, we used remote sensing to analyze the spatial and temporal variation in the normalized difference vegetation index (NDVI) and GPP in the growing season under different LULCs in southwest China. Results showed: (1) From 2000–2019, the forest area in southwest China had increased by 2.1%, while the area of cropland and grassland had decreased by 3.2% and 5.5%, respectively. Furthermore, there are significant differences in spatial variation patterns. (2) NDVI and GPP in the growing season showed a general increasing trend (p < 0.01); vegetation coverage is dominated by high coverage to highest coverage and medium coverage to high coverage transfer. (3) Under different LULCs, the migration directions of NDVI and GPP were different. The center of gravity migration of highest and medium coverage shifted to the southeast by 1.69° and to the northwest by 1.81°, respectively. The results showed the ecosystem evolution and will help to guide the maintenance measure of ecosystem balance and sustainable development.

Border polje soil in Southwest China originated from non-karst areas: Evidence from geochemical fingerprint data

The purpose of this study was to provide scientific evidence to inform decisions on sediment mitigation strategies. A sediment fingerprinting approach was applied to identify soil sources for a border polje (BP) between karst (K) and non-karst (NK) areas in Southwest China. Three composite geochemical fingerprints, composed of basic, conservative, and high variability fingerprints, were used to quantify source contributions from two original groups (geology and land use), and three new classifications (two-, three-, and four-clusters) obtained using the k-means cluster analysis. The bi-plot, range test, tracer variation rate, and virtual mixture were used to test the reliability of each model configuration. The five classifications enabled the identification of > 85.7 % of the source samples. The two-cluster classification was consistent with the geology; the three-cluster divided the K into slope and depression, and the four-cluster further partitioned the NK into hydro-fluctuation belt of reservoirs (HFLRs) and highlands. The goodness of fit for these models was generally > 75 % and uncertainties were < 7.1 %. The HFLRs contributed > 90 % of soil parent material in the BP. The contribution of HL to the dry land near the NK in the BP was lower than that of HFLRs. Depressions contributed more than half to the dry land near the foothills of the limestone in the BP rim, followed by HFLRs. These findings highlight that the fluviatile sediments from NK areas significantly contribute to the BP. Hence, the identification of soil sources in the BP requires an evaluation from the perspective of hydrology, geology, and anthropogenic activities.

Stability Analysis of Karst Tunnels Based on a Strain Hardening–Softening Model and Seepage Characteristics

There are more and more tunnel projects in the karst-developed areas in Southwest China. Affected by karst caves and water, karst tunnels often experience geological disasters such as local collapses and water inrush. A simplified rock stress hardening-softening model was established based on the triaxial compression test results of two kinds of carbonatite to accurately analyze the deformation and water inrush characteristics of the surrounding rocks after karst tunnel excavation. The total stress–strain curve of rocks was simplified into four linear stages: the linear elastic stage, strain hardening stage, strain-softening stage, and residual stage. The volumetric strain–axial strain curve was simplified into four corresponding linear stages: the elastic expansion stage, slow expansion stage, rapid expansion stage, and stable expansion stage. The stress hardening–softening model was used to deduce the relationship between the rocks’ mechanical parameters such as cohesion, internal friction angle, dilatancy angle, and plastic strain, as well as the relationship between seepage characteristic parameters such as permeability coefficient, porosity, and volumetric strain. A karst tunnel in Chongqing, China was taken as the engineering background. The stress hardening–softening constitutive model and seepage characteristic parameters were applied to the FLAC3D numerical simulation by the programming language FISH to analyze the stability and water inrush characteristics of karst tunnels in overlying confining caves. The results showed that rock masses between the cave and tunnel were prone to overall sliding instability. Confined water in the karst cave intruded into the tunnel through the shear-slip rupture zone on both sides instead of the shortest path. Two water inrush points existed on the tunnel surface. The variation law of the permeability coefficients of the surrounding rocks could more truly reflect whether there was a seepage channel between the tunnel and karst cave, as well as the permeable area and water inrush speed of the seepage channel. The work provides a new idea for the stability control of karst tunnels.

The Evolution and Determinants of Ecosystem Services in Guizhou—A Typical Karst Mountainous Area in Southwest China

Due to rapid urbanization and economic development, the natural environment and ecological processes have been significantly affected by human activities. Especially in ecologically fragile karst areas, the ecosystems are more sensitive to external disturbances and have a hard time recovering, thus studies on the ecosystem services in these areas are significant. In view of this, we took Guizhou (a typical karst province) as the research area, evaluated the ecosystem service value (ESV) according to reclassified land uses and revised equivalent factors, and investigated the determinants of ecosystem services based on geographic detection. It was found that the total ESV showed a prominent increase trend, increasing from 152.55 billion CNY in 2000 to 285.50 billion CNY in 2020. The rise of grain prices due to growing social demands was the main factor in driving the increase of ESV. Spatially, the ESVs of central and western Guizhou were lower with cold spots appearing around human gathering areas, while that of southern and southeastern Guizhou were higher with hot spots that formed in continually distributed woodland. Moreover, the ESV per unit area and its change rate in karst regions were always lower than that in non-karst areas. Precipitation and temperature were the dominant nature factors while cultivation and population density were the main anthropogenic effects driving the evolution of ecosystem services. Therefore, positive human activities as well as rational and efficient land-use should be guided to promote the coordinated and high-quality development of ecology and the economy.

The avant-gardism of socially engaged art in contemporary China: Aestheticizing everyday lives at the Yangdeng Art Cooperatives

This article sheds light on the place of avant-gardism in socially engaged art and how it is reformulated in practice, through critically examining the art practices of the Yangdeng Art Cooperatives, a socially engaged art project in a rural area of Southwest China, where artists create various collaborative artworks and site-specific projects with the local people. I argue that the project contributes to an avant-garde mode of socially engaged art through aestheticizing the ordinariness of the everyday. I term this process ‘ordinary aesthetics’. This term demonstrates potential connections in our everyday lives and redefines the relationship between aesthetics and politics by regarding aesthetics as a perceivable sensate and a distribution of the sensible. In aiming to promote the ordinary, artists engage in local residents’ everyday lives by transforming their ordinary objects, spaces, and incidents into works of art. It is art that makes their ordinariness extraordinary. Technically, the artists blur the boundary between the real and the fictional to aestheticize the everyday lives of local residents. In their practices, ordinary aesthetics consequently becomes a means to rediscover the avant-gardism of socially engaged art.

The Infection Route of Tomato Zonate Spot Virus in the Digestive System of Its Insect Vector Frankliniella occidentalis.

Tomato zonate spot virus (TZSV) is a phytopathogen of the genus Orthotospovirus (Bunyaviridae) that is widespread in many areas of Southwest China. TZSV is mainly transmitted by Frankliniella occidentalis, but its exact infection route remains unclear. To explore this issue, we detected the nucleocapsid protein of TZSV in the digestive systems of first-instar F. occidentalis nymphs fed with TZSV-infected pepper leaves. TZSV infection in the F. occidentalis digestive system begins within 4 h post-first access to diseased plants: The foregut is likely the primary site of infection, and primary salivary glands (PSGs) are the destination. There are three potential routes for TZSV transmission from the alimentary canal to the PSGs: (1) virus dissemination from the midgut to hemocoel followed by movement to the PSGs; (2) accumulation in midgut epithelial cells and arrival at PSGs via tubular salivary glands and efferent ducts; and (3) arrival at epitheliomuscular cells of the forepart of the midgut and movement along the ligament to the PSGs. We tested the transmission efficiency of F. occidentalis in second-instar nymphs and female and male adults. TZSV was transmitted in a persistent-propagative mode by both nymphs and adults, with adults appearing to show slightly higher transmission efficiency than nymphs. We confirmed the presence of all three routes for TZSV transmission in F. occidentalis and determined that like other Orthotospoviruses, TZSV is transmitted in a persistent-propagative manner. These results should facilitate the control of TZSV-related diseases and further our understanding of the transmission biology of Orthotospoviruses in general.

Characterization of Soil-Plant Leaf Nutrient Elements and Key Factors Affecting Mangoes in Karst Areas of Southwest China

Baise city is one of the largest producers of mangoes, with this agricultural industry located in the karst region of Southwest China. However, calcium-rich and alkaline soils, severe soil fragmentation, and poor water and fertilizer retention capacity contribute to low mango yields and are key issues that limit the development of the mango industry in karst areas. Our study objectives were to identify the soil factors that limit mango growth and yield in the karst region of Southwest China, and to determine how these growth- and production-limiting conditions vary between landscape positions. This study analyzed the differences in soil nutrient and element contents in mango leaves, and used a Random Forest algorithm to calculate the eigenvalues of the mango leaf and soil elemental indices in the different geomorphic parts (slopes, transition zone, passes, high-yielding depressions, and low-yielding depressions) of the karst peak-cluster depressions. The key factors affecting the mango leaves and soil were screened based on the diagnostic results and the eigenvalues. The results showed that for the elemental contents of Fe, Mg, Ca, and Mn in the mango leaves in the different geomorphic parts of the karst, the peak-cluster depressions were generally deficient and varied significantly. The contents of available B (AB), soil organic matter (SOM), pH, total nitrogen, available Fe, available Mn, alkaline hydrolysis nitrogen, exchangeable Ca (Caex), exchangeable Mg, and other indices in the soils differed significantly, and AB, available Zn, and available K (AK) showed low or very low content levels. In addition, the key soil factors limiting mango yield in the karst areas were AB, fulvic acid, SOM, Fe, Mn, Caex, soil water, and AK; and the key mango leaf factors were Ca, Mn, Fe, Zn, and Mg. Consequently, the characteristics of soil water content, pH, and soil organic matter may be the main drivers affecting the differences in the mango yield and the elemental characteristics. These findings suggest that the addition of organic fertilizer could improve the quality and yield of mangoes in karst areas.

Direct and indirect effects and feedbacks of biomass burning aerosols over Mainland Southeast Asia and South China in springtime

Southeast Asia is one of the largest biomass burning (BB) source regions in the world. In order to promote our understanding of BB aerosol characteristics and environmental impacts, this study investigated the emission, composition, evolution, radiative effects, and feedbacks of BB aerosols from Mainland Southeast Asia during 15 March to 15 April 2019 by using an online-coupled regional chemistry/aerosol-climate model RIEMS-Chem. Model results are compared against a variety of ground and vertical observations, indicating a generally good model performance for meteorology, aerosol chemical compositions, and aerosol optical properties. It is found that BB aerosols contributed significantly to regional particulate matter (PM), accounting for up to 90 % of the near-surface PM2.5, BC, and OC concentrations over the BB source regions of north Mainland Southeast Asia and for approximately 30–70 % over wide downwind areas including most areas of southwest China and portions of south China. At the top of atmosphere (TOA), BB aerosols exerted a positive all-sky radiative effect (DREBB) up to 25 W/m2 over north Vietnam and south China, a negative DREBB up to −10 W/m2 over Myanmar, western Thailand, and southwest China. Meanwhile, the indirect radiative effect (IREBB) was consistently negative, with the maximum of −10 W/m2 over downwind areas with cloud coverage, e.g., from north Vietnam to most of south China. The subregional (95–125°E and 10–30°N) and period mean DREBB and IREBB at TOA were estimated to be 0.69 W/m2 and − 0.63 W/m2, respectively, leading a total radiative effect (TREBB) of 0.06 W/m2 at TOA. The radiative effects of BB aerosols led to decreases in sensible and latent heat fluxes, near-surface temperature, PBL height, and wind speed of 6.0 Wm−2, 9.0 Wm−2, 0.26 °C, 38.7 m, and 0.1 m/s, respectively, accompanied with an increase in RH of 1.9 %, averaged over the subregion and the study period. The accumulated precipitation during the study period was apparently reduced by BB aerosols from east Thailand to south China, with the maximum reduction up to 14 cm (exceeding 40 %) over north Vietnam and south China. TREBB tended to increase mean near-surface PM2.5 and its component concentrations, with the maximum percentage increase up to 24 % over the BB source regions of north Mainland Southeast Asia, resulting from the combined effects of dynamic and chemical feedbacks. DREBB generally dominated over IREBB in the feedback-induced PM2.5 concentration changes.

Traditional beliefs, culture, and local biodiversity protection: An ethnographic study in the Shaluli Mountains Region, Sichuan Province, China

Located on the southeastern Qinghai-Tibet Plateau, the Shaluli Mountains Region (SMR) is an important conservation priority area in Southwest China’s highly biodiverse Hengduan Mountains. The SMR’s ecology is complex and topographically diverse, with unique composition of abundant flora and fauna. Historically and currently a majority-Tibetan region, Tibetan Buddhism has significantly affected most local people’s views on the natural environment. According to Tibetan religious theories and doctrines, the Shaluli Tibetans traditionally abstain from killing wild animals, believe in reincarnation (e.g., karmic cause and effect), the equality of all living beings, and the belief that everything has spirits. To understand how these beliefs and practices influenced the SMR’s ecology and biodiversity, and how modernization pressures affect them, we conducted a three-year ethnobiological field investigation in seven SMR counties and a neighboring city. The traditional worldview in this relatively remote region has profoundly shaped the lifestyles, customs, and behavioral norms of the local religiously-observant Tibetans. These beliefs have influenced their perspective on the natural world, having an overall positive role in the long-term protection of the local ecological environment and biodiversity. As the surrounding regions have experienced increasing development and modernization pressures that threaten this biodiversity hotspot, Shaluli’s Tibetan Buddhist temples and monks have assumed an active role promoting environmental protection, forest resource stewardship, and wildlife conservation. However, we found that modernization pressures and changing socio-economic conditions have negatively influenced these traditions, resulting in greater likelihood of biological invasions and pollution of the local soil and water sources.

Study of Key Technology of Gob-Side Entry Retention in a High Gas Outburst Coal Seam in the Karst Mountain Area

In the gob-side entry retaining by roof cutting (GERRC) technique, pressure is offloaded via directional roof cutting, and a roadway is automatically formed due to the ground pressure and rock-breaking expansion. To improve the application of the theory and technical system of GERRC in the Karst area in Southwest China, this research studies the key technology of GERRC in a high gas outburst coal seam, based on the engineering background of the 39114 working face of the Honglin coal mine. According to the geological conditions of the 39114 working face, by means of formula calculation, UDEC numerical modeling, and on-site drilling peeping, the optimal roof-cutting parameters suitable for the 39114 working face were determined: the roof cutting height was 7 m, the roof cutting angle was 15°, and the spacing of pre-splitting blasting holes was 600 mm. Additionally, the above roof-cutting parameters have achieved good results in the engineering practices of the 39114 transportation roadway, which shows that the technology of GERRC is feasible in high gas outburst mines and achieves the goal of safe and efficient mining.

The effects of weathering of coal-bearing stratum on the transport and transformation of DIC in karst watershed

The mining of medium- to high‑sulfur coal in karst areas has led to serious acidification problems in surface water, thus encouraging a re-evaluation of DIC transformation and CO2 source-sink relationships in karst watersheds. The weathering of limestone and sulfide-rich coal measures jointly influence the pH of the Huatan River in karst areas in Southwest China, which is lower in the rainy season and higher in the dry season. Due to CO2 degassing, DIC concentration tends to decrease along the flow direction, while δ13C-DIC gradually becomes heavier. In general, DIC transformation in the Huatan River is controlled by AMD input, CO2 degassing, organic matter (OM) degradation, and the dissolution and precipitation balance of carbonate minerals in different seasons. In spring, the mineralization of OM from terrestrial and domestic sewage gradually enhances and replenishes DIC in the water. As the pH increases in this season, the capacity for buffering CO2 increases. Meanwhile, OM degradation generates a large amount of CO2 in summer, and carbonic acid begins to dissolve limestone. In autumn, the pH decreases due to the enhanced weathering of sulfide-rich coal measures and the mass input of AMD. Thus, the river shows the ability to drive CO2 outgassing. In winter, CO2 degassing gradually weakens, DIC concentration is at its lowest, and δ13C-DIC reaches the heaviest value.

Pollution Characteristics and Spatial Distribution of Heavy Metals in Coal-Bearing Sandstone Soil: A Case Study of Coal Mine Area in Southwest China.

Soil pollution in coal mining areas is a serious environmental problem in China and elsewhere. In this study, surface and vertical profile soil samples were collected from a coal mine area in Dazhu, Southwestern China. Microscopic observation, concentrations, chemical speciation, statistical analysis, spatial distribution, and risk assessment were used to assess heavy metal pollution. The results show that the weathering of coal-bearing sandstone and mining activities substantially contributed to soil pollution. The concentrations of Fe, Ni, Cu, Zn, Mn, Cd, Hg, and Pb exceeded their background values. Cd caused the most intense pollution and was associated with heavily–extremely contaminated soils. The residual fraction was dominant for most metals, except Cd and Mn, for which the reducible fraction was dominant (Cd: 55.17%; Mn: 81.16%). Zn, Ni, Cd, and Cu presented similar distribution patterns, and Hg and As also shared similar distribution characteristics. Factor 1 represented anthropogenic and lithologic sources, which were affected by mining activities; Factor 2 represented anthropogenic sources, e.g., fertilizers and traffic pollution; and Factor 3 represented the contribution of metals from soil-forming parent material. More than half of the study area had high pollution risk and was not suitable for vegetable cultivation.

Accounting for Value Changes in Cultivated Land Resources within the Karst Mountain Area of Southwest China, 2001–2020

Cultivated land resources are important natural resource assets that are related to food security and sustainable development. Due to the many restrictive factors of the karst landform on agricultural production, the quantity and quality of cultivated land in the karst mountainous areas in Southwest China are poor. Reclaiming cultivated land to develop economy or to avoid transitional reclamation to protect ecology is an important proposition in this area. Analyzing changes in the physical and monetary value of cropland resources can help us to formulate more reasonable policies for the development and utilization of cultivated land resources, and to achieve a win-win scenario for economic development and ecological protection. Using multi-source remote sensing data and 20-year landcover data obtained by the GEE platform, this paper evaluated the cropland resources of the karst mountain areas of China at the pixel level. It was found that under the apparent outflow of the physical account of the cultivated land resources, the monetary value still maintained growth, proving that the current cultivated land-use policy in Guizhou Province has significantly improved the value of local cultivated land resources.

Effect of COVID-19 Response Policy on Air Quality: A Study in South China Context

Mass suspension of anthropogenic activities is extremely rare, the quarantine due to the coronavirus disease 2019 (COVID-19) represents a natural experiment to investigate the impact of anthropogenic activities on air quality. The mitigation of air pollution during the COVID-19 lockdown has been reported from a global perspective; however, the air pollution levels vary in different regions. This study initiated a novel synthesis of multiple-year satellite observations, national ground measurements towards SO2, NO2 and O3 and meteorological conditions to evaluate the impact of the COVID-19 lockdown in Beihai, a specific city in a less developed area in southwest China, to reveal the potential implications of control strategies for air pollution. The levels of the major air pollutants during the COVID-19 lockdown (LP) and during the same period of previous years (SP) were compared and a series of statistical tools were applied to analyze the sources of air pollution in Beihai. The results show that air pollutant levels decreased with substantial diversity during the LP. Satellite-retrieved NO2 and SO2 levels during the LP decreased by 5.26% and 22.06%, while NO2, SO2, PM2.5 and PM10 from ground measurements during the LP were 25.6%, 2.7%, 22.2% and 22.2% lower than during SP, respectively. Ground measured SO2 concentrations during the LP were only 2.7% lower than during the SP, which may be attributed to uninterrupted essential industrial activities, such as power plants. Polar plots analysis shows that NO2 concentrations were strongly associated with local emission sources, such as automobiles and local industry. Additionally, the much lower levels of NO2 concentrations during the LP and the absence of an evening peak may highlight the significant impact of the traffic sector on NO2. The decrease in daily mean O3 concentrations during the LP may be associated with the reduction in NO2 concentrations. Indications in this study could be beneficial for the formulation of atmospheric protection policies.

Co-Application of Tetramycin and Matrine Improves Resistance of Kiwifruit against Soft Rot Disease and Enhances Its Quality and Amino Acids.

Soft rot disease caused by Botryosphaeria dothidea and Phomopsis sp. is the most serious fungal disease of the kiwifruit production area in southwest China. In this work, the role of the co-application of tetramycin and matrine in the resistance of kiwifruit fruits against soft rot disease and its effects on development, quality and amino acids of kiwifruit fruits were investigated. The results indicate that matrine exhibited an outstanding toxicity against B. dothidea RF-1 and Phomopsis sp. RF-2 with EC50 values of 0.442 and 0.332 mg kg−1. The foliar co-application of 0.3% tetramycin aqueous solutions (AS) 5000-fold liquid + 0.5% matrine AS 1000-fold liquid could effectively control soft rot disease with a control efficacy of 82.68%, which was significantly (p < 0.05) higher than 75.19% of 0.3% tetramycin AS 5000-fold liquid and significantly (p < 0.01) higher than 68.50% of 0.5% matrine AS 500-fold liquid. Moreover, the co-application of tetramycin and matrine was more effective than tetramycin or matrine alone in improving disease resistance, quality and amino acids of kiwifruit fruits. This study highlights that the co-application of tetramycin and matrine can be used as a practicable, cost-effective and environmentally friendly candidate or alternative approach for controlling soft rot disease of kiwifruit.

Integrated taxonomy unveils new species of Trigonalyidae (Insecta, Hymenoptera) from Yunnan, China

Trigonalyidae are rarely collected hyperparasitoids that attack the larvae of Ichneumonoidea, and Tachinidae associated with phytophagous sawfly or Lepidopteran larvae, or primary endoparasitoids of Vespidae larvae. Trigonalyidae mainly occur in tropical and subtropical regions, but recent studies indicate that they are found to be fairly common in mountainous regions. In this study, DNA barcoding methods based on sequences of the COI gene were used to discriminate Trigonalyidae species from Yunnan Province, which is situated in a mountaineous area of southwest China. In total, 25 COI sequences belonging to 14 morphospecies of four genera were obtained. The intraspecific pairwise distances ranged from 0 to 3.3% and the interspecific pairwise distances ranged from 5.3% to 17.3%. The delimitations of all studied species are congruent with the morphological identification results in both ABGD and bPTP methods. Based on both morphological and molecular analyses, four species from Yunnan are described as new: Jezonogonalos eburnalva Zhang &amp;amp; Chen, sp. nov., Lycogaster umbonata Chen &amp;amp; van Achterberg, sp. nov., Taeniogonalos albidorsalis Zhang &amp;amp; Chen, sp. nov., and T. paradoxica Zhang &amp;amp; Chen, sp. nov.

Seismic response analysis of single-pylon suspension bridge under random ground motion

The finite element model of suspension bridge was established according to the actual bridge engineering in Southwest area of China. In order to simulate the random ground motion model accurately and efficiently, the orthogonal random function ground motion modeling method based on Priestley evolution spectrum theory is adopted. The dimensionality reduction simulation of random ground motion is realized, and the simulated ground motion samples are input into the finite element model to carry out the time history analysis. Finally, the seismic response of the bearing and pylon is analyzed and important conclusions are drawn.

Large scale rocky desertification reversal in South China karst

The karst area in southwest China is, in recent decades, one of the world’s regions with the fastest vegetation growth and increase in aboveground biomass. The improvement in the ecological conditions within this region can, to a large extent, be attributed to ecological protection projects. However, it remains unclear whether the observed increase in vegetation cover could mitigate rocky desertification at large scale. In this study, we utilized information from large field campaigns in the years 2005, 2011, and 2016, supported by satellite imagery interpretation and statistics on ecological protection projects, to explore the impact of restoration efforts on rocky desertification mitigation and vegetation resilience/resistance. The results show that restoration efforts caused a net decrease of 26.14% in areas affected by rocky desertification from 2005 to 2016. The larger the restoration efforts, the stronger the decrease in rocky desertification areas, and also the vulnerability of landscapes towards desertification; the probability of rocky desertification occurring decreased almost linearly with increased restoration efforts. In addition, both vegetation resilience and resistance against climate variations increased with restoration efforts. Restoration efforts were mainly responsible for the recovery of the ecosystem, showing that human impact is the main driver for the reversal of rocky desertification. Our study provides scientific evidence on rocky desertification control being an important step towards a sustainable development of the landscapes of Southwest China.

Effects of multi-metal exposure on the risk of diabetes mellitus among people aged 40-75 years in rural areas in southwest China.

Aims/IntroductionMetals play an important role in diabetes mellitus. This cross‐sectional study aimed to evaluate the overall, individual and interactive effects of multi‐metal exposure on the prevalence of diabetes mellitus, impaired fasting glucose (IFG) rate and fasting blood glucose (FBG) levels.Materials and MethodsThe FBG levels of a study population from a cadmium (Cd)‐polluted area (n = 250) and an unpolluted area (n = 204), and the metal levels, including magnesium, calcium (Ca), iron (Fe), zinc (Zn), arsenic (As), Cd, copper and lead (Pb) in blood and urine were detected. The study population was divided into a normal fasting glucose group, an IFG group and a diabetes mellitus group on the basis of FBG levels.ResultsThe IFG rate and diabetes mellitus prevalence were negatively associated with blood Cd and urine Zn levels (IFG rate: odds ratio [OR] 0.780, 95% confidence interval [CI] 0.655–0.928; OR 0.622, 95% CI 0.465–0.831. Diabetes mellitus prevalence: OR 0.506, 95% CI 0.288–0.888; OR 0.609, 95% CI 0.395–0.939), the IFG rate was positively associated with urine Fe levels (OR 1.876, 95% CI 1.290–2.778), and diabetes mellitus prevalence was positively associated with urine Pb and blood Fe levels (OR 1.185, 95% CI 1.022–1.376; OR 1.008, 95% CI 1.001–1.014). A linear negative correlation was observed between FBG levels and blood Cd, and non‐linear inverted U‐shaped associations were found between FBG levels and Zn, Pb and copper in urine.ConclusionsThis research suggests that multi‐metal exposure, especially Cd, Fe, Zn, copper and Pb, is linked to diabetes mellitus, and the interactive effects of multiple metals require further exploration.

The chain mediating role of cognitive styles and alienation between life events and depression among rural left-behind children in poor areas in Southwest China

BackgroundCompared with no-left-behind children, left-behind children show more psychological and behavioral problems, among which depression is the most common and most influential psychological problem in childhood. Many studies have documented the impact of life events on depression among left-behind children, but few studies have focus on the mediating mechanisms behind this relationship. Based on theoretical and empirical research on cognitive style and alienation, this study constructed a chain mediation model to test whether cognitive style and alienation play a mediating role in life events and depression of left-behind children. MethodsWe recruited 13,035 participants from 25 districts and counties in Chongqing. After screening, 5127 questionnaires of left-behind children were included in the data analysis. They all completed self-report measures of demographic information, life events, cognitive styles, alienation and depression. We used SIF, CDI, ASLEC, CCSQ and IAP to collect the information of the variables and used the SPSS to analyze the data. Results(1) There were significant positive correlations among life events and depression. (2) Left-behind children's depression was affected by life events through 3 different pathways: the mediating role of cognitive styles, the mediating role of alienation, and the chain mediating role of both cognitive styles and alienation. LimitationsThis is a cross-sectional study and the data used in our study is self-reported. ConclusionsCognitive styles and alienation could mediate the association between life events and depression among left-behind children.