Metalens for Accelerated Optoelectronic Edge Detection under Ambient Illumination.

Analog systems may allow image processing, such as edge detection, with low computational power. However, most demonstrated analog systems, based on either conventional 4-f imaging systems or nanophotonic structures, rely on coherent laser sources for illumination, which significantly restricts their use in routine imaging tasks with ambient, incoherent illumination. Here, we demonstrated a metalens-assisted imaging system that can allow optoelectronic edge detection under ambient illumination conditions. The metalens was designed to generate polarization-dependent optical transfer functions (OTFs), resulting in a synthetic OTF with an isotropic high-pass frequency response after digital subtraction. We integrated the polarization-multiplexed metalens with a polarization camera and experimentally demonstrated single-shot edge detection of indoor and outdoor scenes, including a flying airplane, under ambient sunlight illumination. The proposed system showcased the potential of using polarization multiplexing for the construction of complex optical convolution kernels toward accelerated machine vision tasks such as object detection and classification under ambient illumination.

Polychromatic Dual-Mode Imaging with Structured Chiral Photonic Crystals.

Optical spatial differentiation is a typical operation of optical analog computing and can single out the edge to accelerate the subsequent image processing, but in some cases, overall information about the object needs to be presented synchronously. Here, we propose a multifunctional optical device based on structured chiral photonic crystals for the simultaneous realization of real-time dual-mode imaging. This optical differentiator is realized by self-organized large-birefringence cholesteric liquid crystals, which are photopatterned to encode with a special integrated geometric phase. Two highly spin-selective modes of second-order spatial differentiation and bright-field imaging are exhibited in the reflected and transmitted directions, respectively. Two-dimensional edges of both amplitude and phase objects have been efficiently enhanced in high contrast and the broadband spectrum. This work extends the ingenious building of hierarchical chiral nanostructures, enriches their applications in the emerging frontiers of optical computing, and boasts considerable potential in machine vision and microscopy.

Phosphorus dynamics in volcanic soils of Weizhou Island, China: implications for environmental and agricultural applications.

The dynamics of phosphorus are intricately governed by geological and ecological processes. Examining phosphorus dynamics in volcanic islands can enhance our comprehension of its behavior within such unique geological systems. However, research on phosphorus dynamics in volcanic islands remains limited. We investigated the phosphorus content of volcaniclastic rocks and basalt soils from Weizhou Island, China, to understand the influencing factors on phosphorus dynamics. The results indicate that in the volcaniclastic profile, phosphorus concentrates at 20-40 cm (17 mg/kg), decreases at 40-60 cm (11.9 mg/kg), and increases at 80-200 cm up to 46.4 mg/kg proximate to the bedrock, for the basalt profile, phosphorus content increases from the surface (80.2 mg/kg) towards the bedrock (83.9 mg/kg). The differences in phosphorus distribution between volcaniclastic rocks and basalts reflect the influence of parent material, rock weathering degree, carbonate content, topographic elevation, sea level changes, and geological activities. A strong positive correlation (R = 0.96907) between total and available phosphorus has been observed, suggesting that total phosphorus content effectively predicts available phosphorus content. Volcaniclastic rocks in wharves and high-elevation areas show low total phosphorus, while forest land with dense vegetation and neutral to alkaline soil supports higher total phosphorus due to enhanced bioavailability for plant absorption and utilization. Overall, the basalt soil of the volcanic island Weizhou Island demonstrates superior long-term fertility compared to the volcaniclastic soil. Despite its low total phosphorus content, it mainly exists in a highly bioavailable form, facilitating plant absorption, which is crucial for enhancing agricultural yields and ecosystem restoration on volcanic islands.

Spatial differentiation and driving factors of the high-quality development of undertakings for the aged of China.

BACKGROUND: Promoting the high-quality development (HQD) of undertakings for the aged is an important action to proactively respond to the rapid population aging in China. This study analyzes spatial differentiation and driving factors of the HQD of China's undertakings for the aged. METHODS: Based on a quantitative indicator system consisting of old-age social security, elder care services, health care service and older adults' social participation, the HQD levels of 31 Chinese provincial administrative regions during 2013-2019 are measured by using the entropy weight method. Spatial panel regression models are used to analyze the impact of population aging, economic development and digital technology on the HQD of undertakings for the aged. RESULTS: The comprehensive level of the HQD slightly increased from 0.212 to 2013 to 0.220 in 2019, and the overall level was low. The HQD of the eastern region was the highest (0.292), followed by the western region (0.215), and the central region was the lowest (0.151). The high-high cluster type was mainly distributed in the eastern region; the low-low cluster type was mainly distributed in the western and central regions. Economic development and digital technology have significant positive effects while population aging has significant negative effects on the HQD of undertakings for the aged. CONCLUSION: There is a significantly spatial differentiation in the HQD of China's undertakings for the aged. In order to promote the HQD of undertakings for the aged, it is necessary to identify development gaps through making HQD evaluation and to focus on the indicators that are critical in maintaining sustainable economic development and to develop digital technology in order to get rid of those gaps.

A holistic model of health inequalities for health policy and state administration: a case study in the regions of the Czech Republic.

BACKGROUND: Health inequities exist within and between societies at different hierarchical levels. Despite overall improvements in health status in European Union countries, disparities persist among socially, economically, and societally disadvantaged individuals. This study aims to develop a holistic model of health determinants, examining the complex relationship between various determinants of health inequalities and their association with health condition. METHODS: Health inequalities and conditions were assessed at the territorial level of Local Administrative Units (LAU1) in the Czech Republic. A dataset of 57 indicators was created, categorized into seven determinants of health and one health condition category. The necessary data were obtained from publicly available databases. Comparisons were made between 2001-2003 and 2016-2019. Various methods were employed, including composite indicator creation, correlation analysis, the Wilcoxon test, aggregate index calculation, cluster analysis, and data visualization using the LISA method. RESULTS: The correlation matrix revealed strong relationships between health inequality categories in both periods. The most significant associations were observed between Economic status and social protection and Education in the first period. However, dependencies weakened in the later period, approaching values of approximately 0.50. The Wilcoxon test confirmed variations in determinant values over time, except for three specific determinants. Data visualization identified persistently adverse or worsening health inequalities in specific LAU1, focusing on categories such as Economic status and social protection, Education, Demographic situation, Environmental status, Individual living status, and Road safety and crime. The health condition indices showed no significant change over time, while the aggregate index of health inequalities improved with widened differences. CONCLUSION: Spatial inequalities in health persist in the Czech Republic, influenced by economic, social, demographic, and environmental factors, as well as local healthcare accessibility. Both inner and outer peripheries exhibit poor health outcomes, challenging the assumption that urban areas fare better. The combination of poverty and vulnerabilities exacerbates these inequalities. Despite the low rates of social exclusion and poverty, regional health inequalities persist in the long term. Effectively addressing health inequalities requires interdisciplinary collaboration and evidence-based policy interventions. Efforts should focus on creating supportive social and physical environments, strengthening the healthcare system, and fostering cooperation with non-medical disciplines.

Spatiotemporal variation of cold requirements for leaf coloration and its environmental cues over the northern deciduous broadleaved forests.

Evaluating the interactions between cold requirements for leaf coloration and environmental cues is crucial for understanding the mechanisms of leaf senescence and accurately predicting autumn phenology. Based on remote sensing-derived and ground-observed leaf coloration dates for deciduous broadleaf forests during 1981-2014, we determined location-specific cold requirements for autumn leaf coloration and assessed their spatiotemporal changes. Then, we revealed the major environmental cues of cold requirements and their spatial differentiation. Results show that cold requirements have nonsignificant trends during the past decades at 57.9% of pixels. The interannual variation of cold requirements was mainly influenced by growing-season accumulated temperature (GDDgs) at 35.8% of pixels and accumulated growing season index (AGSI) at 23.2% of pixels, but less affected by leaf unfolding and low precipitation index (LPI). The increase in GDDgs or AGSI may decrease cold requirements, and vice versa. The spatial differentiations of the effects of GDDgs and AGSI depend highly on local summer temperature among climatic classifications with similar humidity conditions. Specifically, the effects of GDDgs on cold requirements concentrated in humid regions with warmer summers, while that of AGSI mainly occurred in humid and winter dry regions with cooler summers. Higher summer temperatures would strengthen the effects of GDDgs and reduce the effects of AGSI on cold requirements. These findings deepen the understanding of the influences of environmental factors on leaf senescence progress and suggest that the shifts of factors affecting cold requirements under global warming may enlarge the uncertainty in predicting autumn leaf coloration dates.

Optical edge detection based on high-efficiency dielectric metasurface.

Optical edge detection is a useful method for characterizing boundaries, which is also in the forefront of image processing for object detection. As the field of metamaterials and metasurface is growing fast in an effort to miniaturize optical devices at unprecedented scales, experimental realization of optical edge detection with metamaterials remains a challenge and lags behind theoretical proposals. Here, we propose a mechanism of edge detection based on a Pancharatnam-Berry-phase metasurface. We experimentally demonstrated broadband edge detection using designed dielectric metasurfaces with high optical efficiency. The metasurfaces were fabricated by scanning a focused laser beam inside glass substrate and can be easily integrated with traditional optical components. The proposed edge-detection mechanism may find important applications in image processing, high-contrast microscopy, and real-time object detection on compact optical platforms such as mobile phones and smart cameras.

Reconfigurable Metasurface for Image Processing.

Optical Fourier transform-based processing is an attractive technique due to the fast processing times and large-data rates. Furthermore, it has recently been demonstrated that certain Fourier-based processors can be realized in compact form factors using flat optics. The flat optics, however, have been demonstrated as static filters where the operator is fixed, limiting the applicability of the approach. Here, we demonstrate a reconfigurable metasurface that can be dynamically tuned to provide a range of processing modalities including bright-field imaging, low-pass and high-pass filtering, and second-order differentiation. The dynamically tunable metasurface can be directly combined with standard coherent imaging systems and operates with a numerical aperture up to 0.25 and over a 60 nm bandwidth. The ability to dynamically control light in the wave vector domain, while doing so in a compact form factor, may open new doors to applications in microscopy, machine vision, and sensing.

[Spatial distribution characteristics of rare and endangered medicinal plant resources in Gansu province].

Gansu province is located at the intersection of the three plateaus(Qinghai-Tibet Plateau, Inner Mongolia Plateau, and Loess Plateau) and the three river basins(Yellow River Basin, Yangtze River Basin, and inland river basin). The complex eco-environment and climate conditions here have created rich and diverse vegetation. Therefore, it is of great significance to study the spatial distribution characteristics of rare and endangered medicinal plant resources in Gansu province for formulating reasonable protection po-licies and promoting the development of medicinal plant industry. The data of rare and endangered medicinal plant resources in 87 counties of Gansu province were collected from results of the fourth general survey. The spatial distribution and the high-or low-value gathering area of rare and endangered medicinal plant resources in Gansu province were analyzed by geostatistical methods such as exploratory spatial data analysis, trend surface analysis, and Anselin Local Moran's I. The eco-environment characteristics of the high-or low-value gathering area were analyzed with the data of vegetation type, soil texture classification, annual mean temperature, annual mean precipitation, and elevation. Furthermore, the relationships of the spatial distribution and diversity with the geographical environment of rare and endangered medicinal plants in Gansu province were analyzed to provide support for the restoration and protection policy making of these plant resources.

[Quantitative analysis of total content differentiation and driving factors of phenolic acids in Angelicae Sinensis Radix of Gansu Dao-di herbs from perspective of geographical space].

Dao-di herbs, produced in a specific region and screened through long-term clinical application, is characterized by high stable quality, good efficacy, and high popularity. With favorable climate conditions, Gansu gives birth to the Dao-di herbs Angelicae Sinensis Radix which is widely used in clinical practice, and multiple regions in Gansu, with similar ecological environment produce Angelicae Sinensis Radix. In this study, the spatial correlation and difference of phenolic acid content in Angelicae Sinensis Radix from Dao-di producing areas, emerging producing areas, and emerging planting areas in Gansu were analyzed based on ArcGIS to explore the "quality(chemical type)" characteristics of genuine Angelicae Sinensis Radix. Moreover, spatial distribution law and main driving factors of the total phenolic acid content in Angelicae Sinensis Radix in Gansu were analyzed based on geodetecctor. This study is expected to lay a basis for Dao-di research and production regionalization of Angelicae Sinensis Radix.

High-Index Dielectric Metasurfaces Performing Mathematical Operations.

Image processing and edge detection are at the core of several newly emerging technologies, such as augmented reality, autonomous driving, and more generally object recognition. Image processing is typically performed digitally using integrated electronic circuits and algorithms, implying fundamental size and speed limitations, as well as significant power needs. On the other hand, it can also be performed in a low-power analog fashion using Fourier optics, requiring, however, bulky optical components. Here, we introduce dielectric metasurfaces that perform optical image edge detection in the analog domain using a subwavelength geometry that can be readily integrated with detectors. The metasurface is composed of a suitably engineered array of nanobeams designed to perform either first- or second-order spatial differentiation. We experimentally demonstrate the second-derivative operation on an input image, showing the potential of all-optical edge detection using a silicon metasurface geometry working at a numerical aperture as large as 0.35.

The spatial differentiation of quality of rural life based on natural controlling factors: A case study of Gansu Province, China.

The laws of regional differentiation of county development and influencing factors on the quality of rural life (QRL), affect not only the vital interests of rural residents but also the scientific implementation of rural revitalization strategy. In this paper, taking 87 counties (cities, districts) of Gansu Province as the region of study, we constructed five-dimensional model of QRL index. Then, Pearson correlation, spatial coupling, geographical detector and tradeoff analysis methods were used to analyze the QRL's spatial differentiation and quantitively identify its natural controlling factors. Further, we discussed the mechanism of spatial differentiation of QRL in Gansu Province and provided recommendations for improving QRL. The results show that: (1) QRL in Gansu Province is characterized by spatial heterogeneity and agglomeration, and decreases from west to east. There are five hot spots and four cold spots of QRL. (2) Altitude, slope, precipitation, and distance to the provincial capital (DTTPC) are the natural controlling factors of spatial differentiation of QRL in Gansu Province. Their influences are quantified to be 0.19, 0.37, 0.37 and 0.20, respectively. (3) The tradeoff between QRL and precipitation is the strongest, with root mean square deviation (RMSD) of 0.293. The tradeoff between QRL and altitude/slope/DTTCC are of medium level and decrease successively, with values of 0.238, 0.255 and 0.2 respectively. (4) According to the different influences of natural controlling factors on QRL, Gansu Province was classified into three regional types: natural environment restricted type, resource abundance restricted type and economic location restricted type. Thus, we can improve the QRL on the basis of identifying driving mechanisms in different regions, make policies according to local conditions, and further promote the rural development.

Overview and recommendations for regionalized life cycle impact assessment.

PURPOSE: Regionalized life cycle impact assessment (LCIA) has rapidly developed in the past decade, though its widespread application, robustness, and validity still faces multiple challenges. Under the umbrella of UNEP/SETAC Life Cycle Initiative, a dedicated cross-cutting working group on regionalized LCIA aims to provides an overview of the status of regionalization in LCIA methods. We give guidance and recommendations to harmonize and support regionalization in LCIA for developers of LCIA methods, LCI databases, and LCA software. METHOD: A survey of current practice among regionalized LCIA method developers was conducted. The survey included questions on chosen method spatial resolution and scale, the spatial resolution of input parameters, choice of native spatial resolution and limitations, operationalization and alignment with life cycle inventory data, methods for spatial aggregation, the assessment of uncertainty from input parameters and model structure, and variability due to spatial aggregation. Recommendations are formulated based on the survey results and extensive discussion by the authors. RESULTS AND DISCUSSION: Survey results indicate that majority of regionalized LCIA models have global coverage. Native spatial resolutions are generally chosen based on the availability of global input data. Annual modelled or measured elementary flow quantities are mostly used for aggregating characterization factors (CFs) to larger spatial scales, although some use proxies, such as population counts. Aggregated CFs are mostly available at the country level. Although uncertainty due to input parameter, model structure, and spatial aggregation are available for some LCIA methods, they are rarely implemented for LCA studies. So far, there is no agreement if a finer native spatial resolution is the best way to reduce overall uncertainty. When spatially differentiated models CFs are not easily available, archetype models are sometimes developed. CONCLUSIONS: Regionalized LCIA methods should be provided as a transparent and consistent set of data and metadata using standardized data formats. Regionalized CFs should include both uncertainty and variability. In addition to the native-scale CFs, aggregated CFs should always be provided, and should be calculated as the weighted averages of constituent CFs using annual flow quantities as weights whenever available. This paper is an important step forward for increasing transparency, consistency and robustness in the development and application of regionalized LCIA methods.

[Detection and analysis of effect of geographical environmental factors on spatial distribution of artemisinic acid in Artemisia annua].

Dao-di herbs are preferred by long-term clinical application of Chinese medicine, they are produced in a specific area and affected by the specific production and processing methods. Dao-di herbs have a high reputation, compared with other regions produced by the same kind of herbs with good quality, good efficacy and stable quality characteristics. Geo-herbal is a unique concept that has been formed by the history of Chinese civilization for thousands of years and the history of Chinese medicine. According to the definition of geo-herbal, it can be seen that there are some differences in the quality and efficacy of the same kind of medicinal herbs in different regions, and there is some similarity in the specific area. In this study, based on the content of artemisinic acid in sampling points and its potential environmental factors, the effects of geographical environment factors on the spatial distribution of artemisinic acid content in Artemisia annua were studied by using the geophysical model. The results show that the spatial distribution of artemisinic acid content is the result of a combination of multiple factors. The effects of environmental factors on the spatial distribution of artemisinic acid were in the order of soil type (0.233)> radiation (0.208)> vegetation type (0.192)> elevation (0.171)> sunshine (0.170)> annual mean temperature (0.153) >annual precipitation (0.111)> slope (0.110)> relative humidity. Among them, the soil type and the amount of radiation are the main influencing factors, and the main influencing area is in the soil type as the initial soil and the average annual radiation of 1 200-1 400 kWh•m⁻². The main influencing factors selected in this study can be used to monitor the spatial distribution of artemisinic acid by remote sensing technology, so as to provide the theoretical basis for the cultivation of A. annua.

Environmental and Socioeconomic Health Inequalities: a Review and an Example of the Industrial Ostrava Region.

BACKGROUND AND AIM: According to the World Health Organization (WHO) more than 2 million premature deaths and 7 million of total deaths each year can be attributed to the effects of air pollution. The contribution of air pollution to the health status of population is estimated to be about 20%. Health is largely determined by factors outside the reach of healthcare sector, including low income, unemployment, poor environment, poor education, and substandard housing. The aim of the paper was to review a current knowledge of relationships among air pollution, socioeconomic health inequalities, socio-spatial differentiation, and environmental inequity. The relationships were demonstrated on an example of the Ostrava region. Also basic approaches to health valuation were reviewed. RESULTS: Social differences are reasons both for health inequalities and spatial patterns of unprivileged area housing. In urban environments with poor air quality there is also a large concentration of low income residents. Less affluent population groups are more often affected by inadequate housing conditions including second-hand smoking and higher environmental burden in their residential neighbourhoods. Environmental injustice is highly correlated with other factors that link poverty with poor health, including inadequate access to medical and preventive care, lack of availability of healthful food, lack of safe play spaces for children, absence of good jobs, crime, and violence. CONCLUSIONS: The theoretical background and also results of the studies brought evidence that population health is affected by both socioeconomic and environmental inequalities. Air pollution is unevenly distributed in Ostrava and is related to distribution of socially disadvantaged environment and social exclusion as well.

Spatial differentiation and influencing factors of effective phosphorus in cultivated soil in the water source area of the mid-route of South-to-North water transfer project.

The long-term application of phosphate fertilizers in agricultural production leads to a large accumulation of phosphorus in the soil. When it exceeds a certain limit, phosphorus will migrate to surrounding water bodies through surface runoff and other mechanisms, potentially causing environmental risks such as eutrophication of water bodies and increasing the risk of water source pollution. This study takes Shiyan City, the water resources area of the mid-route of the South-to-North Diversion Project (MSDP), as the study area. Based on 701 sampling points of topsoil, geostatistics and geodetectors were used to explore the spatial heterogeneity and influencing factors of available phosphorus (AP) in the topsoil of the area. The results show that the effective phosphorus content in the topsoil of the study area ranges from 0.30 to 146.00 mg/kg, with an average value of 14.28 mg/kg, showing strong variability characteristics. Geostatistical analysis shows that among all theoretical models, the exponential model has the best fitting effect, with a lump gold effect of 0.447 and a range of 82,000 m. The soil available phosphorus content shows an increasing trend from the Central Valley lowlands to the surrounding mountainous hills. Among them, elevation is the main controlling factor for the spatial variation of available phosphorus in the topsoil, followed by soil types, planting systems, annual precipitation, and organic matter. The non-linear enhancement or dual-factor enhancement among various environmental factors reveals the diversity and complexity of spatial heterogeneity affecting available phosphorus content in cultivated soil. This study could provide scientific references for maintaining ecological security in the water source area of the MSDP, improving the precise management of AP, and enhancing cultivated land quality.

Unveiling the spatial differentiation drivers of major soil element behavior along traffic network accessibility.

Advancements in transportation networks have induced a spatial-temporal convergence effect, accelerating socio-economic elements flow and dismantling the conventional "core-periphery" urbanization gradient. Accessibility of transportation networks emerges as a reliable indicator of urbanization. There has been a growing global and Chinese focus on the various forms of metal pollution in urban soil. This study aims to investigate the driving forces and effects of urbanization factors (Gross Domestic Product (GDP), value added of secondary industries (VA), night light (NL), population density (PD), and road density (Distance)), soil property factors (pH, electrical conductivity (EC), and total organic carbon (TOC)), and topographic factors (elevation (DEM), aspect, and slope) on toxic heavy metal elements (Cd, As, and Hg) and trace elements (Mn, Ti, V) in surface soil (0-20 cm) across varying accessibility levels in the Beijing-Tianjin-Hebei urban agglomeration. Results reveal significant influence of accessibility on Cd and Hg levels (p < 0.05), with higher accessibility areas displaying elevated element concentrations. According to the evaluation results of the single-factor pollution index, Cd and V have the highest pollution exceedance rates (93.18% and 75.76%, respectively). Moran's Index results highlight typical spatial clustering of elements, with hotspots in areas of high accessibility. Urbanization has led to distinct spatial agglomeration patterns in element concentrations and environmental factors. Geographic detector analysis reveal that in low accessibility areas, metal element pollution and distribution are influenced by a combination of complex factors, including soil properties (pH), terrain conditions (DEM), and the urbanization process (VA). In high accessibility areas, toxic heavy metal elements are primarily driven by urbanization factors, largely influenced by transportation activities, industrial development, and population density, while elements Mn, Ti, and V are still influenced by both natural processes and urbanization activities. These findings suggest that urbanization intensifies the impact on potential toxic elements in soil, and that trace elements are increasingly affected by urbanization, warranting further attention.

Protective effects of antibiotic resistant bacteria on susceptibles in biofilm: Influential factors, mechanism, and modeling.

In environmental biofilms, antibiotic-resistant bacteria facilitate the persistence of susceptible counterparts under antibiotic stresses, contributing to increased community-level resistance. However, there is a lack of quantitative understanding of this protective effect and its influential factors, hindering accurate risk assessment of biofilm resistance in diverse environment. This study isolated an opportunistic Escherichia coli pathogen from soil, and engineered it with plasmids conferring antibiotic resistance. Protective effects of the ampicillin resistant strain (AmpR) on their susceptible counterparts (AmpS) were observed in ampicillin-stress colony biofilms. The concentration of ampicillin delineated protective effects into 3 zones: continuous protection (<1 MIC of AmpS), initial AmpS/R dependent (1-8 MIC of AmpS), and ineffective (>8 MIC of AmpS). Intriguingly, Zone 2 exhibited a surprising "less is more" phenomenon tuned by the initial AmpS/R ratio, where biofilm with an initially lower AmpR (1:50 vs 50:1) harbored 30-90 % more AmpR after 24 h growth under antibiotic stress. Compared to AmpS, AmpR displayed superiority in adhesion, antibiotic degradation, motility, and quorum sensing, allowing them to preferentially colonize biofilm edge and areas with higher ampicillin. An agent-based model incorporating protective effects successfully simulated tempo-spatial dynamics of AmpR and AmpS influenced by antibiotic stress and initial AmpS/R. This study provides a holistic view on the pervasive but poorly understood protective effects in biofilm, enabling development of better risk assessment and precisely targeted control strategies of biofilm resistance in diverse environment.

[Spatial Differentiation Characteristics and Influencing Factors of Surface Soil Cd in Karst Plateau Area of Guiyang City].

In order to explore the spatial differentiation characteristics and variation law of soil Cd content in a high geological background area, 14 421 topsoil samples were collected from topsoil in the karst area of Guiyang City. Global Moran's I index, cold hot spot analysis, semi-variance function, and Kriging interpolation were used to reveal the spatial structure and distribution law of soil Cd content. The influence of environmental factors on soil Cd content and its main controlling factors were analyzed through analysis of variance and geographic detector. The results showed that： ① The Cd content of karst surface soil in Guiyang varied from 0.03 to 1.36 mg·kg-1, with an average of 0.440 mg·kg-1, which was 1.77 times and 5.95 times the Guizhou soil Cd background value and Chinese soil Cd background value, respectively. The over-standard rate of soil Cd was 30%, which was 4.29 times that of 7% of soil Cd in China. ② There was a significant spatial positive correlation of soil Cd content, showing an aggregation trend in the global space, whereas in the local region, the northeast and southwest were hot spots, and the north was a cold spot. The nugget coefficient of soil Cd content was 10.37%, indicating that soil Cd was mainly affected by structural factors. ③ In terms of spatial distribution, soil Cd showed different accumulation trends. In some massive soils, such as Xifeng County, Xiuwen County, Qingzhen City, Huaxi District, and Nanming District, the soil ω（Cd）was less than 0.3 mg·kg-1. The soil ω（Cd）was between 0.3 and 0.6 mg·kg-1,and soil Cd in Baiyun District, Wudang District, Guanshan Lake area, and Yunyan area as a whole lied within this range. The soil ω（Cd）between 0.6 and 0.9 mg·kg-1 was concentrated in the southwest of Qingzhen City, the south of Huaxi District, and the north of Kaiyang County, whereas soil ω（Cd） between 0.9 and 1.2 mg·kg-1 was mainly concentrated in the southwest of Qingzhen City. The extreme value of soil Cd content （ > 1.2 mg·kg-1） was mostly distributed in Kaiyang County, Xiuwen County, Qingzhen City, and Huaxi District. ④ The results of analysis of variance and geo-detector showed that different environmental factors had significant effects on the spatial differentiation of soil Cd, but their explanatory power on soil Cd content varied： stratum （0.176 5） > soil type （0.026 0） > organic matter （0.025 1） > altitude （0.010 5） > parent rock （0.007 3） > land use （0.006 4） > pH （0.001 3）, and the interaction between stratum and arbitrary environmental factors was the greatest. Therefore, stratum was the main factor affecting the spatial differentiation of soil Cd content.

Analysis of railway accessibility in Fujian Province and the influence of economic development on its spatial differentiation.

Understanding railway accessibility supports railway regulation and development, but few studies consider different perspectives. We study the spatial distribution of accessibility indicators at the county (city) scale in Fujian Province by spatiotemporal syntax and weighted average travel time using railway timetable data. Export trade, rich commercial activities, and high-speed rail had a significant positive effect on objective accessibility. Fuzhou, Sanming, and Longyan were main transfer centers. The most accessible nodes based on weighted average travel time formed a "U"-shaped corridor along the coast. The county-wide average accessibility was 1.72 h. According to spatiotemporal syntax, local general public budget expenditure (0.758993) and export volume of goods-total retail sales of consumer goods (0.956257) had the most interactive impact, while according to weighted average accessibility, import volume of goods (0.618447) and per capita gross regional product-import volume of goods (0.878573) did. These results provide reference for transportation planning and regional development in Fujian Province.