Driving model of land use change on the evolution of carbon stock: a case study of Chongqing, China.

Terrestrialecosystems are significant carbon sinks and are crucial for understanding the regional and global carbon cycles, energy flow, and climate change. As land use change is a significant process affecting ecosystem carbon stocks and striving for land degradation neutrality (LDN), studying it is essential for comprehending the evolution of regional carbon sink functions and achieving sustainable development goals. The drastically diverse land use patterns in each of the study area's regions resulted in significant differences in carbon stock. This study explores the evolution traits of carbon stocks based on land use data and their driving mechanisms in Chongqing during the past 30 years by using spatial analysis, the InVEST model, and geographic probes. The results demonstrate that from 1990 to 2020, land degradation in Chongqing was made worse by the demand for land for construction land, but the strategy of converting cropland back to forests raised the carbon stock of forest land. The overall result is a decrease in total carbon stocks of 5.1078 Tg or 1.5%. The main pathway for carbon loss pathway in the evolution of carbon stock is the conversion of cropland to construction land, and the primary carbon compensation pathway is the conversion of grassland and cropland to forest land, with a spatial distribution characterized by "higher in the whole area and obvious local differences." The land use intensity index has the most significant influence on the evolution of carbon stock. Moreover, the interaction of pairwise factors played a more important role in affecting the evolution of carbon stocks than did each factor individually. The case study in this paper shows that land use change is a significant driving mechanism for the evolution of carbon stock, and the development of a driving model theory is appropriate for deciphering the trajectory of carbon stock evolution and offering research suggestions for other regions.

Prevalence of ideal cardiovascular health and its relationship with relative handgrip strength in rural northeast China.

Objectives: We aimed to investigate ideal cardiovascular health (CVH), its relationship with handgrip strength, and its components in rural China. Methods: We conducted a cross-sectional study of 3,203 rural Chinese individuals aged ≥35 years in Liaoning Province, China. Of these, 2,088 participants completed the follow-up survey. Handgrip strength was estimated using a handheld dynamometer and was normalized to body mass. Ideal CVH was assessed using seven health indicators (smoking, body mass index, physical activity, diet, cholesterol, blood pressure, and glucose). Binary logistic regression analyses were performed to assess the correlation between handgrip strength and ideal CVH. Results: Women had a higher rate of ideal cardiovascular health (CVH) than men (15.7% vs. 6.8%, P < 0.001). Higher handgrip strength correlated with a higher proportion of ideal CVH (P for trend <0.001). After adjusting for confounding factors, the odds ratios (95% confidence interval) of ideal CVH across increasing handgrip strength tripartite were 1.00 (reference), 2.368 (1.773, 3.164), and 3.642 (2.605, 5.093) in the cross-sectional study and 1.00 (reference), 2.088 (1.074, 4.060), and 3.804 (1.829, 7.913) in the follow-up study (all P < 0.05). Conclusion: In rural China, the ideal CVH rate was low, and positively correlated with handgrip strength. Grip strength can be a rough predictor of ideal CVH and can be used to provide guidelines for improving CVH in rural China.

Output characteristics and driving factors of non-point source nitrogen (N) and phosphorus (P) in the Three Gorges reservoir area (TGRA) based on migration process: 1995-2020.

Although physical models at present have made important achievements in the assessment of non-point source pollution (NPSP), the requirement for large volumes of data and their accuracy limit their application. Therefore, constructing a scientific evaluation model of NPS nitrogen (N) and phosphorus (P) output is of great significance for the identification of N and P sources as well as pollution prevention and control in the basin. We considered runoff, leaching and landscape interception conditions, and constructed an input-migration-output (IMO) model based on the classic export coefficient model (ECM), and identified the main driving factors of NPSP using geographical detector (GD) in Three Gorges Reservoir area (TGRA). The results showed that, compared with the traditional export coefficient model, the prediction accuracy of the improved model for total nitrogen (TN) and total phosphorus (TP) increased by 15.46 % and 20.17 % respectively, and the error rates with the measured data were 9.43 % and 10.62 %. It was found that the total input volume of TN in the TGRA had declined from 58.16 × 104 t to 48.37 × 104 t, while the TP input volume increased from 2.76 × 104 t to 4.11 × 104 t, and then decreased to 4.01 × 104 t. In addition Pengxi River, Huangjin River and the northern part of Qi River were high value areas of NPSP input and output, but the range of high value areas of migration factors has narrowed. Pig breeding, rural population and dry land area were the main driving factors of N and P export. The IMO model can effectively improve prediction accuracy, and has significant implications for the prevention and control of NPSP.

Trends in ethnic disparities in clinical cardiovascular health among Chinese adults from 2016-2020.

BACKGROUND AND AIMS: Little is known about the long-term trends in ethnic differences in cardiovascular health (CVH) in China in recent years. This study aimed to investigate ethnic differences in CVH and identify long-term trends in China. METHODS AND RESULTS: This survey was based on the physical examination data of Tacheng Prefecture in China from 2016 to 2020, and included 1,947,938 physical examination participants aged over 20 years for analysis. The American Heart Association (AHA) criteria were used to evaluate the clinical CVH of the subjects. The time trends from 2016 to 2020 were assessed using a weighted linear regression model stratified by ethnicity. The ethnic groups included Han, Kazakh, Hui, Mongolian, Uyghur, among others. The mean ideal clinical cardiovascular score was highest in Hui and lowest in Uyghur. The scores increased from 5.99 (5.95-6.03) to 6.11 (6.08-6.14) in Kazakh males and from 6.05 (5.99-6.11) to 6.11 (6.06-6.16) in Hui males among participants (Plinear trend < 0.001). The scores for the other groups declined significantly from 2016 to 2020(Plinear trend ＜ 0.05). In the sensitivity analysis, the trend remained unchanged after calculating the body mass index (BMI) cut-off for China. CONCLUSION: Clinical CVH differences still exist among different ethnic groups, with a decline in CVH from 2016 to 2020 in all except Kazakh and Hui males. This may indicate a higher incidence and poorer prognosis of cardiovascular disease in the future and can provide guidelines for improving CVH.

The coupling effect of socio-economic and eco-environment and land use transformation in mountainous areas-a case of the Fengjie County in the Three Gorges Reservoir Area, China.

Revealing the general laws of land use transformation (LUT) under the coupling evolution of different socio-economic and eco-environment (SE-EE) in mountainous areas is of great significance for rational use of land resources, regional socio-economic development, and eco-environment protection. This paper constructs a research framework of LUT under the coupling evolution of SE-EE and takes Fengjie County as an example to conduct a case study. The results show (1) the socio-economic development level and eco-environment quality showed an overall growth trend from 2000 to 2020, showed the distribution pattern of high in the Yangtze River valley and low in the mountainous areas, and low in the Yangtze River valley and high in the mountainous areas respectively. (2) The coupling evolution of SE-EE showed five types: synchronous development of SE-EE, socio-economic development and ecological retarded, socio-economic retarded and ecological restoration, low socio-economic development level, and low eco-environment quality. (3) The transformation of land use quantity, structure, and function corresponded to the coupling evolution of SE-EE. Cultivated land was reduced when the socio-economic development level was relatively high, and the function changed from production to ecological and eco-economic. When the eco-environment quality was high, cultivated land was reduced, and the function changed from production to ecological. (4) The framework constructed in this paper is universal to the mountainous areas represented by the Three Gorges Reservoir Area (TGRA) and the plain areas where the LUT and SE-EE evolution are different from the mountainous areas.

Spatiotemporal characteristics of air pollution in Chengdu-Chongqing urban agglomeration (CCUA) in Southwest, China: 2015-2021.

Studying the spatiotemporal characteristics of air pollutants in urban agglomerations and their response factors will help to improve the quality of urban living. In combining air quality monitoring data and wavelet analysis from the Chengdu-Chongqing urban agglomeration (CCUA), this study assessed the spatiotemporal distribution characteristics and influential factors of air pollutants on daily, monthly and annual scales. The results showed that the concentration of air pollutants in the CCUA has decreased year by year, and air quality has improved. Except for O3, pollutants in autumn and winter were higher than those in summer. The spatial distribution of air pollutants was obvious distributed in Chengdu, Chongqing, Zigong and Dazhou. Pollution incidents were mainly concentrated in winter. The 6 air pollutants and air quality index (AQI) have dominant periods on multiple time scales. AQI showed positive coherence with PM2.5 and PM10 on multiple time scales, and obvious positive coherence with SO2, CO, NO2 and O3 in the short term scale. AQI was not strongly correlated with the fire point, but exhibited obvious negative coherence in the long term scale. In addition, AQI showed an obvious positive correlation with temperature and sunshine hours in short term, and a clear negative correlation with humidity and rainfall. The research results of this paper will provide a reference for pollution prevention and control in the CCUA.

[Output Characteristics and Driving Mechanism of Agricultural Non-point Source (AGNPS) Pollutant in Plain and Valley Region of Upper Yangtze River, China].

Research on the pattern and mechanism of agricultural non-point source (AGNPS) pollution in rural areas is of great significance to the governance of the regional ecological environment. This study took the plain and hilly area of the upper Yangtze River as the research area, relied on multivariate data, and used a pollutant measurement method based on spatial distance correction, and Kriging interpolation and logistic regression methods (LR) were used to study the emission pattern and impact mechanism of AGNPS pollutants. The results showed that the total emissions of COD, BOD5, NH4+-N, TN, and TP increased by 15.46×104, 25.66×104, 3.49×104, 1.26×104, and 0.38×104 t, respectively, and the emissions of these five pollutants had strong spatial regularity from 2005 to 2015. The Chengdu Plain, the hills in central Sichuan, and the parallel ridge valley farming areas in eastern Sichuan were the high-value areas, whereas urban areas and hinterland of the Three Gorges Reservoir (TGRA) were low-value areas. The risk levels of COD, BOD5, and NH4+-N increased; TN pollution was more serious; and the emission risk level was gradually increasing. The emission risk of TP was high and had a tendency to continue to deteriorate. The overall risk level was in a spatial pattern of "high in the middle and low in the surrounding area," with extremely high and second-highest risk levels in a mosaic distribution. The Chengdu Plain and the Parallel Ridge and Valley areas in eastern Sichuan were high-risk clusters. The main driving factors of non-point source pollution from 2005 to 2010 were grain output, livestock and poultry production, and the number of rural populations, which were categorized as "production-driven" GDP and annual average precipitation were the main driving factors, which were categorized as "production and life synergy-driven." These results can provide a basis for analyzing the driving mechanism and prevention and control of NPSP in the hilly area of the upper Yangtze River.

Simulation of the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region--based on the improved export coefficient model.

Nonpoint source pollution is one of the primary causes of eutrophication of water bodies. The concentrations and loads of dissolved pollutants have a direct bearing on the environmental quality of receiving water bodies. Based on the Johnes export coefficient model, a pollutant production coefficient was established by introducing the topographical index and measurements of annual rainfall. A pollutant interception coefficient was constructed by considering the width and slope of present vegetation. These two coefficients were then used as the weighting factors to modify the existing export coefficients of various land uses. A modified export coefficient model was created to estimate the dissolved nitrogen and phosphorus loads in different land uses in the Three Gorges Reservoir Region (TGRR) in 1990, 1995, 2000, 2005, and 2010. The results show that the new land use export coefficient was established by the modification of the production pollution coefficient and interception pollution coefficient. This modification changed the single numerical structure of the original land use export coefficient and takes into consideration temporal and spatial differentiation features. The modified export coefficient retained the change structure of the original single land use export coefficient, and also demonstrated that the land use export coefficient was not only impacted by the change of land use itself, but was also influenced by other objective conditions, such as the characteristics of the underlying surface, amount of rainfall, and the overall presence of vegetation. In the five analyzed years, the simulation values of the dissolved nitrogen and phosphorus loads in paddy fields increased after applying the modification in calculation. The dissolved nitrogen and phosphorus loads in dry land comprised the largest proportions of the TGRR's totals. After modification, the dry land values showed an initial increase and then a decrease over time, but the increments were much smaller than those of the paddy field. The dissolved nitrogen and phosphorus loads in the woodland and meadow decreased after modification. The dissolved nitrogen and phosphorus loads in the building lot were the lowest but showed an increase with the progression of time. These results demonstrate that the modified export coefficient model significantly improves the accuracy of dissolved pollutant load simulation for different land uses in the TGRR, especially the accuracy of dissolved nitrogen load simulation.

[Remote sensing analysis of forest resources characteristics in main ecological restoration counties in the Three-gorge area based on the 2nd-class inventory data].

Based on high-resolution SPOT-5 images, combined with topographic (1:10000) calculating terrain-bit index, the distribution characteristics of woodlands in different terrain niches, and the buffer radii of different roads, water bodies and settlements were identified by using ArcGIS space overlay and buffer analysis function. Results showed that woodland resources were abundant, and arbor woodland and shrub land were the main species, which mainly distributed in two mountain areas (Fangdou Mountain, Qiyao Mountain) affected by topographic restriction and woodland natural basis. The woodland terrain niche distribution index showed an overall upward trend with increasing terrain niche gradient, especially for the arbor woodland and shrub land, while the other woodland types presented an opposite trend. The percentage of woodland area occupying the corresponding buffer radius around the roads, waterbodies and settlements had a strong similarity with the woodland terrain niche distribution index. Only around the settlements, bamboo forest, sparse woodland and immature woodland occupied higher percentages of the woodland area of the corresponding buffer radius than that of arbor woodland and shrub land. Woodland distribution was mainly controlled by large landform patterns of mountain features, while the distribution of woodlands in the different terrain niches and the different buffer radii of roads, waterbodies and settlements were driven mainly by duress of human activities under the auspices of the large landform patterns.

[Effects of conservational tillage on aggregate composition and organic carbon storage in purple paddy soil].

A 13 year experiment was conducted to study the effects of conservational tillage on the aggregate composition and organic carbon storage in purple paddy soil of Sichuan Basin. The results showed that under no-tillage and ridge culture (rice-rape) (NR-RR), no-tillage and plain culture (rice-rape) (NP-RR), no-tillage and ridge culture (rice-green manure) (NR-RGM), tillage and ridge culture (rice-rape) (TR-RR), and tillage and plain culture (rice-rape) (TP-RR), the proportion of macroaggregates in 0-10 cm soil layer was 23%, 69%, 9%, 36%, and 28% higher than that under conventional tillage (CT) (12%), respectively, while in 10-20 cm soil layer, this proportion under conservational tillage was 9%-38% lower than that under CT. The organic carbon storages in the macroaggregates at the depth of 0-10 cm were 13%, 31% and 32% higher under no-tillage and ridge culture (rice-fallow) (NR-RF), NR-RR and NR-RGM than under CT, respectively, while that at the depth of 10-20 cm was 28%-54% lower. The differences in organic carbon storage between macro- and microaggregates were smaller in 10-20 cm layer than in 0-10 cm layer. Under conservational tillage, the organic carbon storage was 8%-28% higher in 0-10 cm layer but 4%-22% lower in 10-20 cm layer, compared with that under CT. After converted from CT to conservational tillage for 13 years, the mean organic carbon sequestration rate was 53 g x m(-2) x a(-1) and 25 g x m(-2) x a(-1) at the depths of 0-10 cm and 10-20 cm, while under CT, it was 26 g x m(-2) x a(-1) and 33 g x m(-2) x a(-1), respectively. Conservational tillage was favorable to the formation of macroaggregates in surface soil layer and the enhancement of soil total organic carbon storage.

[Responses of regional ecological service value to land use change: A case study of Shapingba County in Chongqing].

Land use has significant effects on the products and services provided by ecosystem, through its interaction with ecosystem processes and services. Taking Shapingba County in Chongqing as an example, and by the Costanza method and ecological sensitivity analysis, this paper analyzed the effects of land use change on ecological service value. The results indicated that from 1992 to 2002, the ecological service value of this County was from dollar 1.74 x 10(7) to dollar 16.8 x 10(7), i. e. , dollar 0.54 x 10(5) was lost. Accordingly, each hectare land suffered an average loss of dollar 13.62. The ecological service value coefficient assigned to different categories of land use had little effects on the total ecological service value, and the total change of ecological service value was inelastic. The summation of the ecological service value coefficients assigned to cultivated land, forestland and garden land was very close to regional actualities. But, the ecological service value coefficient assigned to the waters was higher than the actual value, while rectifying 30 percent of the previous coefficient by 5 667 dollar x hm(-2) x yr(-1) would be very close to the actual one. Applying Costanza method to estimate the change of regional ecological service value was practicable, and would make a reference for the evaluation of land use benefits and the organization of land use planning.

Response of CH4 emission of paddy fields to land management practices at a microcosmic cultivation scale in China.

The terrestrial ecosystem may be either a source or a sink of CH4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice (T1), no-tillage and ridge culture of rice (T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation (T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH4 emission from paddy fields under these land management practices. In 1996 and 1998, CH4 emission was 71.48% and 78.82% (T2), 65.93% and 57.18% (T3), and 61.53% and 34.22% (T4) of that in T1 during the rice growing season. During the non-rice growing season, CH4 emission from rice fields was 76.23% in T2 and 38.69% in TI. The accumulated annual CH4 emission in T2, T3 and T4 in 1996 decreased by 33.53%, 63.30% and 65.73%, respectively, as compared with that in T1. In 1998, the accumulated annual CH4 emission in T1, T2, T3 and T4 was 116.96 g/m2, 68.44 g/m2, 19.70 g/m2 and 11.80 g/m2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH4 emission observed. The relative contribution of various influencing factors to CH4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global (climatic) change.