With water resource shortages becoming a global concern, water conservation is one of the key factors in the sustainable development of watershed ecosystems. However, previous studies of water conservation have focused on annual mean water conservation, which does not reflect changes in water conservation on shorter time scales. Shorter time scales have more significant responses than longer timescales. An annual scale reflects the supply function of the water culverts, whereas a shorter time scale reflects the function of stagnant flood replenishment. Thus, we analyzed the annual, monthly, and daily changes in water conservation in the Zengjiang River Basin, an important water source area and ecological barrier in Guangzhou, from 1959 to 2018. The WEP-L distributed hydrological model and water-balance equations were used to explore the supply, regulation, and peak reduction and replenishment of the water conservation dryness functions. The results indicate that the annual mean water conservation in the Zengjiang River Basin was 685.7 mm from 1959 to 2018, with a non-significant decreasing rate (-1.30 mm/a) during this period. This decreasing trend indicates that the water supply capacity of the basin decreased, which is not conducive to the water security of the basin and downstream areas. Therefore, relevant policies should be formulated and measures should be taken to improve the water conservation capacity of the basin. The multi-year average monthly water conservation in the Zengjiang River Basin was positive in January‒September and negative in October‒December, with non-significant increases in water conservation in January, March, June, November, and December, and non-significant decreases in the other months. The trend ranged from -0.04 to -0.67 mm/a during the entire study period. Water conservation changes in the Zengjiang River Basin during pre-flood, post-flood, and dry-water periods indicate that the basin's ability to regulate water conservation runoff weakened. The maximum 1-day, 3-day, 5-day, and 7-day periods in the Zengjiang River Basin were positive, whereas the minimum 1-day, 3-day, 5-day, and 7-day periods were negative. Except for the minimum 5-day and 7-day periods, the other six daily extreme water conservation indicators exhibited non-significant increasing trends. The maximum water conservation values indicate that the peak reduction capacity increased, while the minimum water conservation values indicate that the capacity to replenish depletion decreased in 1- and 3-day periods and increased in 5- and 7-day periods. Spatially, the annual water conservation trend was low in the southeastern and northern parts of the basin, and high in the southwestern part of the basin. Annual, monthly, and daily water conservation levels in the Zengjiang River Basin from 1959 to 2018 embodied its supply, regulation, peak reduction, and replenishment of depletion functions, respectively. The correlation coefficients between water conservation and precipitation were significantly higher than those between evapotranspiration and surface runoff, thereby indicating that precipitation was the most important factor influencing water conservation. The findings of this study reveal multi-temporal evolutionary processes and functional differences in water conservation and provide a scientific basis for ecological protection and construction.

Determining the chemical characteristics of atmospheric precipitation and its source contributions is critical for improving atmospheric environmental quality and water security. In this study, we analyzed the pH, Electrical Conductivity (EC), and major ion concentrations of precipitation from 2000 to 2021 at 29 monitoring stations in the Pearl River Delta (PRD), which typically experiences acid rain. Correlation analysis, the Positive Matrix Factorization (PMF) model, and other statistical methods were used to analyze the correlations between the major ion concentrations and their source contributions. The results indicate that the pH, EC, and Fractional Acidity (FA) of precipitation from 2000 to 2021 ranged from 4.66 ± 0.18 to 5.91 ± 0.45, from 1.63 ± 0.59 to 5.49 ± 1.62 mS/m, and from 0.05 ± 0.06 to 0.19 ± 0.13, respectively. The pH exhibited interannual variations (first decreasing and then increasing), whereas EC and FA exhibited the opposite trend. The total ion concentrations in precipitation ranged from 166.63 ± 46.56 to 631.48 ± 212.83 μeq/L, which first increased and then decreased. The weighted equivalent ion concentrations were in order of \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} > Ca²⁺ > \mathrm{N} {\mathrm{H}}_{\mathrm{4}}^{+} > \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-} > Cl^- > Na⁺ > K⁺ > Mg²⁺ > F^-. \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}, \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-}, Ca²⁺, and \mathrm{N} {\mathrm{H}}_{\mathrm{4}}^{+} were the main ions, accounting for 72.98% of the total concentration. The ratio of the \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} concentration to the total concentration decreased from 32.71% in 2000 to 14.33% in 2021, whereas \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-} increased from 9.03% to 13.74% during the same period. The ratio of \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} to \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-} concentrations ( \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}/ \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-}) decreased by 65.95% from 2000 to 2021. After 2008, the \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}/ \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-} values ranged from 0.5 to 3, and precipitation shifted from a sulfuric acid type to a mixed sulfuric-nitric acid type. This change indicates that increased NO _x emissions in the PRD under urbanization and agricultural intensification altered the structure of precipitation pollution and further increased the complexity of regional air pollution. The ions were highly significantly positively correlated, of which \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-} and \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} had the strongest positive correlation (r=0.69‒0.74). Generally, NO _x and SO₂ are emitted together and enter precipitation via overlapping pathways. Of the six ion sources, coal combustion had the highest contribution rates (a>60%) to \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} and F^-, while secondary inorganic salts contributed 82.30% of the \mathrm{N} {\mathrm{O}}_{\mathrm{3}}^{-}. Agriculture, sea salt, biomass combustion, and dust contributed > 70% of the \mathrm{N} {\mathrm{H}}_{\mathrm{4}}^{+}, Na⁺, K⁺, and Ca²⁺. The contribution rates of secondary inorganic salts to \mathrm{S} {\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-}, Cl^-, and \mathrm{N} {\mathrm{H}}_{\mathrm{4}}^{+} were also greater than 25%. Owing to the increase in motor vehicles driven by urbanization, the impacts of secondary inorganic salt sources on ions in precipitation have become more extensive, and controlling NO _x emissions to effectively control secondary pollution sources is urgently required.

River hydraulic engineering plays a substantial role in maintaining the water-energy-food-economy nexus and coping with climate change. The co-construction of carbon peaking, carbon neutrality goals, and ecological civilization presents new demands for the development of river hydraulic engineering. Building upon an overview of the development of river hydraulic engineering, particular attention has been paid to its impact on the carbon cycle process. A review of the research on carbon cycling indicates that the carbon cycle of river hydraulic engineering is primarily influenced by geographical location, project scale, and operational management, whereas the evaluation results of carbon balance are significantly affected by differences in calculation methods, evaluation systems, and data discrepancies. Analysis of the carbon balance of reservoirs nationwide also revealed that China's reservoir CO₂ flux was slightly higher than the world average, whereas the CH₄ flux was lower. The total carbon storage in reservoir sediments in China is approximately 2.103 billion tons, rising at a rate of 76 million tons per year. Estimation results of carbon emissions reduction in hydropower projects indicate that water conservancy projects have significant functional benefits and demonstrate a noticeable "carbon sink" effect on the energy structure. Assuming that hydropower is entirely replaced by thermal power, hydropower reduces approximately 3,984 Tg (CO_2eq)/a of carbon emissions from the power system, of which small hydropower accounts for approximately 6%. This study also explored policy-oriented issues in the development of river hydraulic engineering, assisting in elucidating the challenges and demands faced by river hydraulic engineering during the period of multi-objective co-construction. These challenges include balancing ecological friendliness to enhance carbon sequestration, ensuring food security, harnessing water resources for economic purposes, maintaining policy continuity, and increasing government credibility. Recommendations for the future include ensuring policy continuity, deepening research on enhancing data sharing, conducting fundamental research, and strengthening multiscale integrated systematic studies. It is necessary to establish a unified carbon balance evaluation system, conduct in-depth research on process-based mechanisms and cumulative effects, and explore the synergy between research, application, and policy development. These efforts will actively promote the innovative development of river hydraulic engineering within the context of ecological civilization construction and the achievement of the "dual carbon goals".

Global precipitation observations have been realized through the development of satellite remote-sensing technology. However, there is a lack of evaluation of remote-sensing precipitation products in complex tropical island terrains. This study used hourly rain gauge data to conduct a multi-scale systematic evaluation of common precipitation products, such as CMORPH, CHIRPS, GsMAP, GPM, MSWEP, ERA5-Land, and PERSIANN, over Hainan Island, providing an in-depth analysis of the precipitation detection capabilities of various products in this region. The main conclusions are: (1) In a multi-temporal scale evaluation, GPM and GsMAP outperformed the other products across all time scales. On a 3-hour scale, GPM and GsMAP showed the highest correlation coefficients (0.53 and 0.52, respectively). On a daily scale, except for PERSIANN, all products showed correlation coefficients above 0.56, with GPM and GsMAP showing the best performance (R = 0.73 and 0.74, respectively). (2) In comparing annual precipitation, Hainan Island's average-annual precipitation over the past 20 years showed a fluctuating trend, with a mean of 1,776.4 mm/a. The CMORPH annual average of 1,765.1 mm/a was the closest to the CHM-PRE dataset, with minimal error. ERA5-Land and MSWEP significantly overestimated (2,504.3 mm/a) and underestimated (1,662.2 mm/a) the average-annual precipitation, respectively. (3) Spatial distribution pattern analysis revealed that the observed multi-year annual precipitation in Hainan Island ranges from 996.9 to 2,368.9 mm, exhibiting an annular-distribution pattern with higher precipitation in the east than in the west and the southwestern mountainous areas than in the northeastern plains. The precipitation range of 1,337.9‒2,287.0 mm observed in GsMAP was the closest to the rain gauge data and particularly matched that of the high-value center in the southeast of the island. (4) In a precipitation trend analysis, CMORPH, ERA5-Land, GPM, MSWEP, CHIRPS, and PERSIANN showed an increasing trend in local areas of Hainan Island, while GsMAP showed a stronger increasing trend. (5) In an analysis of extreme precipitation events, GsMAP, CMORPH, and GPM reproduced the spatiotemporal evolution of extreme precipitation events on a daily scale in Hainan relatively well. GPM better reproduced the spatial and temporal evolution characteristics of typhoon precipitation events in Hainan Island. However, the accuracy of the precipitation estimation still requires improvement. The results of this study not only contribute to our understanding of precipitation products applicable to Hainan but also provide insights for improving satellite-based precipitation products in tropical island environments. These findings underscore the importance of regional validation and the potential of multi-product fusion approaches for enhancing precipitation estimates in complex terrains.

Microbes have consistently coexisted with humans and have profoundly influenced their daily practices. Accompanied by the new materialists' rethinking of the ontology and epistemology of nonhuman matter, and based on the 'Object Oriented Ontology' proposed by Harman, this paper attempt to reinterpret the dynamic relationship between viruses, human bodies, and cities in the process of movement. By reinterpreting the communication patterns between human bodies and viruses, as well as the topological networks between human bodies and cities, this study aimed to reveal the biosocial attributes of cities from the perspective of transcending anthropocentrism." The findings indicate that (1) symptoms and attitudes towards viruses are embodied communication processes between the human body and the virus and that the outcome of embodied communication is influenced by temporal and spatial dimensions. This finding contributes to the reshaping of the humanity-virus relationship, prompting humanity to value the agency of viruses and to confront how viruses coexist and cohabit in the human body and urban spaces; (2) The mobilities of viruses cross boundaries and scales between a human body and cities. By focusing on the mobilities of viruses between extended bodies to explore the interactions between bodies and cities, this study reveals the mobilities and biosocial properties of the city; that is, the city is viewed as a topological biosocial network that transcends boundaries. Using the mask as an example, this study reveals how the extended body affects and alters material connections–that is, how social, policy, and cultural meanings are embedded in the construction and reconstruction of urban topological networks–and how the network of relationships attached to the body creates connections to better cope with the impacts of viral mobilities. Overall, based on the concepts of embodied communication' and an extended body, the results of this study provide new perspectives on micro-mobilities in human geography, enriching the dynamics of the relationship between cities and bodies. First, it re-examines the dichotomy between health and disease as a dynamic relational process by understanding the relationship between humans and viruses from a geographic perspective so that health study pays attention to the dynamics of other elements in the relational network. Second, the findings also expand the connotation and application of the concept of the 'extended body,' enriching the understanding of the dynamic relationship between the body and the city, and revealing the interactions between macro-socio-cultural politics and micro-body behavioral practices in the context of viral pandemics. Viewing the relational nature and attributes of the city through the prism of microbial mobility, draws our attention towards how a city is formed through connections between human and nonhuman matter and exhibits that this relational space is constantly fluid. This turn of thinking, which reflects the connotations and extents of space in a network-nested manner, has inspired geographers to pay attention to the complex network of relationships between people and spaces, where humans, microbes, and cities are seen as a collection of complex relationships. Therefore, the object of urban governance is not limited to humanity but should also be concerned with other nonhuman matters, and the relationships generated between people and nonhuman matters.

As a social, cultural, and spatial phenomenon, the spatial characteristics and dynamics of youth neo-tribes reflect the mode, process, and strategy of interaction with their social environment. However, existing studies mainly regard space as a formation condition and internal characteristic of neo-tribes, while failing to consider it as a key perspective for understanding the social and historical processes of neo-tribes. Therefore, this study constructs an analysis framework based on two spatial analysis paths proposed by Soja(2005)from his ontology of existence: "time-space" and "society-space." Furthermore, "706 Youth Space" is taken as a case study to analyze the spatial characteristics and dynamics of youth neo-tribes. Our results indicate the following: (1) The "706 Youth Space" embodies distinct neo-tribal attributes, including the mobility of its members, common feelings, rituals and symbols, and a shared space. As a neo-tribal space, the socialization of "706 Youth Space" includes emotional resonance and identification, memory generation, and imagination extension. This study supports the summary of the characteristics of neo-tribes in existing studies. Additionally, it reveals the temporal and spatial continuity, rhythm, and spatialization of the instantaneous outbreak of the neo-tribe and emphasizes the spatiality characteristics in the process of its socialization. (2) This study analyzes the relationship between the neo-tribe and its environment through the spatial strategy, and corrects the double illusion of the existing research on the spatial understanding of neo-tribes. The game strategy between the "706" youth neo-tribe and its environment is summarized as space contraction, stimulus diffusion, and space expansion strategy. The youth neo-tribe needs to be embedded in the real social space, and can be preserved and developed through strategic contraction and change. Through space extension strategies such as the opening of space and expansion of relationships, we can promote the connection with the place and make it a bridging space in terms of filling and extensibility of social relations. (3) This study analyzes the role of virtual and physical space in the formation of youth neo-tribes, the embodiment in their survival strategy, and the respective characteristics and relationships of virtual and physical space. Among them, in the formation, strengthening, and identification of neo-tribes, young people change from unfamiliar online members to offline physical space encounters through activities, and form temporary neo-tribes based on common feelings under the guidance of common interests and tastes. After the activity, young participants establish a sense of identity with the youth neo-tribe and apply to join the online community, thus continuing its existence through the virtual space. In terms of survival strategy, through the contraction of offline space, development of online space, and integration of online and offline, the youth neo-tribe realizes its adaptation to the external environment. The study overcomes the limitation of understanding the relationship between online and offline space from the functional viewpoint and reveals the synergy of such space in emotion, identity, and survival strategy of the neo-tribe.

In the era of the knowledge economy, the production, distribution, and application of knowledge play increasingly important roles in the production of regional innovations, and the phenomenon of networking of knowledge interactions is becoming increasingly obvious. Knowledge interactions are an important driving mechanism of urban innovation performance, and the effects of local and non-local knowledge interaction linkages on urban innovation performance need to be clarified. This paper explains urban innovation performance on the basis of the "Network Capital" theoretical framework and argues that it is a function of the stock of network capital in each region; that is, the stock of local and cross-border connected network capital and the interrelationships between the two (complementarity, balance and synergy, etc.) are the key mechanisms driving urban knowledge acquisition and innovation performance. Through the analysis of patent transfer data, this study investigated the classification of Chinese urban innovation network patterns from the perspective of the strength of local (intra-city) and cross-border (inter-city) innovation linkages and analyzed the impacts of local and cross-border knowledge interaction linkages on urban innovation performance. The empirical results for China's biomedical industry led to the following conclusions: (1) The activity of knowledge interactions in Chinese cities is increasing, with the proportion of cross-border linkages steadily rising and the gap between them and local linkages gradually widening. Knowledge interactions in Chinese cities exhibit a high degree of spatial imbalance, with knowledge interactions evolving from being sparse to dense while the imbalance intensifies, exhibiting characteristics such as hierarchy, gradient, and agglomeration. (2) The knowledge interaction portfolio model based on local and cross-border linkages categorizes cities into four types: Networked, Outward-oriented, Inward-oriented, and Isolated. The distribution of Networked-type cities is clearly concentrated in the central and eastern regions, and the spatial bias has been strengthened with the evolution of time. The distribution of Isolated-type cities is biased toward the inland regions, whereas Outward- and Inward-oriented cities are mainly interspersed in the central and western areas, among which Networked-type cities play an extremely important role in the innovation network system and are responsible for the main functions of innovation output. (3) Local and cross-border linkages and their degree of complementarity play a significant role in promoting urban innovation performance. Conversely, the degree of local and cross-border balance and their synergy are insignificant on urban innovation performance. The results show that for the innovative development of China's biomedical industry at the city level, the focus should be on increasing the strength of local and cross-border knowledge interaction linkages as well as the complementary roles of the two, and that it is not appropriate to pursue a balanced and synergistic development of the two at the current stage of development. This study has systematically investigated the roles of the complementary, balanced, and synergistic relationships between local and cross-border linkages in urban innovation performance, and its findings enrich the current literature on "Network Capital."

Given that the chemical industry is the foundation and pillar of the national economy, explorations of its spatial evolution characteristics and influencing factors are of paramount importance for optimizing regional industrial spatial layouts and promoting high-quality development. This study focused on 10,596 chemical enterprises in Guangdong Province and employed spatial analysis methods to delineate the spatial evolution characteristics of the chemical industry in Guangdong from 2000 to 2021 from an industrial chain perspective. Additionally, we applied a negative binomial regression model to analyze the factors affecting the location choices of chemical enterprises. The following are the main conclusions drawn from the results obtained: (1) Overall, the spatial distribution of the chemical industry in Guangdong Province exhibited a southwest-to-northeast trend, with the center shifting along a southeast-to-northwest axis, accompanied by a gradual reduction in distance. This resulted in a general pattern of "agglomeration in the Pearl River Delta region, diffusion along river corridors, and peripheral expansion." The specific spatial distribution pattern can be described as a "central core and two belts," aligning with the industrial development strategies that are driving the western and eastern regions of Guangdong in concert with the Pearl River Delta region. (2) Agglomeration effects within different industrial chains were strengthened and exhibited variations in distribution. Upstream industries were primarily concentrated in Maoming, transitioning from being dispersed to being densely agglomerated and gradually forming a core area in Maoming and a sub-core area on the east bank of the Pearl River. Midstream industries were primarily clustered in the Pearl River Delta and Maoming, with limited distribution in other regions, displaying a pattern of "significant agglomeration in the Pearl River Delta, the emergence of new hotspots in Maoming and Zhanjiang, and scattered development in other areas." Downstream industries clustered in the Pearl River Delta region and expanded toward the northwest, featuring a "significant increase in agglomeration in the Pearl River Delta, with a noticeable gap compared with other regions." (3) Spatial correlations within the chemical industry gradually strengthened, with downstream industries displaying the strongest associations. With regard to inter-industry chain associations, midstream and downstream industries exhibited the closest spatial connections, whereas those between upstream and downstream industries were relatively weaker. (4) The spatial layout of the chemical industry was driven by multiple factors, including location conditions, socioeconomic factors, government actions, and industry linkages. Notably, transportation infrastructure, economic development, labor costs, environmental regulations, and industrial foundations significantly influenced the spatial layout. Furthermore, the factors influencing the spatial distribution of chemical enterprises in different industrial chains varied. Upstream industries tended to favor regions with stringent environmental regulations and higher labor costs. Midstream industries leaned toward areas with good water transportation, strong economic foundations, high labor costs, stringent environmental regulations, and robust industrial bases. Downstream industries shared similar influencing factors with midstream industries and preferred regions with strong industrial links. This study makes two main contributions. The theoretical findings enrich the field of geographical research on the chemical industry and provide specific references for the spatial layouts of other industries. In practical terms, this study is valuable for capturing and reflecting the evolving spatial patterns of the chemical industry and providing decision-making references for local governments seeking to promote its transformation and development.

The primary objective of a regional integration strategy is to foster talent agglomeration and knowledge spillover, thereby enhancing the high-quality development of the regional economy. Extant literature predominantly concentrates on talent distribution and the pattern of knowledge spillover under integration policy. However, scant attention has been paid to the causal inference of regional integration policy on talent aggregation and knowledge spillover. Under the new economic structure of establishing a unified national market and high-quality development, a comprehensive understanding of the evolutionary mechanisms of integration policy in relation to talent aggregation and knowledge spillover is pivotal for shaping regional talent policies and refining theories of population mobility. To address this gap, this study employs time-varying Difference-In-Differences (DID) and spatial DID approaches to empirically assess the influence and underlying mechanisms of regional integration policy within the context of the Yangtze River Delta Urban Agglomeration. The analysis reveals three key findings. First, the integration policy demonstrates a substantial facilitative impact on talent aggregation and knowledge diffusion within the Yangtze River Delta Urban Agglomeration, bolstering these processes by 10.5% and 14.8%, respectively, and exhibiting significant spatial spillover effects. This indicates that the policy not only attracts talent to specific regions but also encourages the spread of knowledge beyond the immediate geographical boundaries of the targeted areas. Second, heterogeneity analysis shows that the policy effectively enhances talent aggregation and knowledge spillover in central cities, with no significant influence observed in peripheral cities. This disparity suggests that central cities, with their advanced infrastructure and economic opportunities, are better positioned to capitalize on the benefits of the integration policy. Furthermore, from a demographic perspective, the policy exhibits a more pronounced positive effect on talent aggregation and knowledge spillovers in medium- and large-scale cities. This trend underscores the importance of city size and demographic factors in the successful implementation of integration policies. Third, mechanistic analysis indicates that the beneficial impacts of the policy on talent concentration are more pronounced in cities characterized by higher levels of urbanization, investment, market integration, education, income level, public service provision, and transportation infrastructure. These factors collectively create an environment conducive to talent attraction and retention, amplifying the effects of the integration policy. Furthermore, the policy has significantly enhanced talent agglomeration by increasing the stock of human capital, highlighting the role of education and skill development in fostering regional economic growth. In conclusion, this study provides a theoretical basis and practical reference for urban agglomerations aiming to spearhead the high-quality advancement of regional economies. By revealing the intrinsic laws and influence mechanisms of regional integration policy, the findings offer valuable insights for policymakers seeking to optimize talent policies and promote sustainable economic development. The empirical evidence highlights the importance of targeted policy interventions that consider the unique characteristics of different urban areas, thereby ensuring a balanced and inclusive approach to regional development. Future research should continue to explore the long-term effects of integration policies and their potential to drive innovation and economic resilience in an increasingly interconnected world.

Talent is a crucial factor for regional development, and its development and cultivation are important dimensions for measuring the innovation capability of a region. Talent attractiveness is the best reflection of the vitality of regional development. The development of the marine economy and the construction of maritime power require continuous attention to maritime talent. Although there is a substantial amount of literature on marine talent, investigations of marine research talent, which is an indispensable part of marine talent, are relatively scarce. This study revealed the flow characteristics and spatial agglomeration features of marine talent, which could provide references for establishing a reasonable mechanism for marine talent flow, enhancing the efficiency of regional talent allocation, and promoting the high-quality development of coastal cities' marine economies. Author information regarding the changes in their affiliations was extracted from research papers published in marine-related core journals in the China National Knowledge Infrastructure (CNKI) from 2000 to 2020, and a corresponding database was constructed. Using complex network analysis methods and techniques, such as ArcGIS and Gephi, the dynamic characteristics of marine research talent mobility were systematically analyzed. The results show that: 1) During the 20-year period, the number of marine research talent mobility showed a changing trend of increasing and then decreasing, and the network exhibited a typical "pyramid structure," which was controlled by a few hub-type node cities. 2) The spatial distribution pattern of marine research talent mobility was relatively stable, forming a diamond-shaped spatial structure with Qingdao as the core and Dalian, Beijing, Shanghai, and Guangzhou as the vertices. Marine research talent migration can be classified into two modes: intracity closed-loop and intercity migration. The proportion of closed-loop migration increased, and the phenomenon of intra-city migration was highlighted. 3) A considerable spatial imbalance existed in the mobility of marine research talent. The spatial distribution of the net inflow of marine research talent tended to be balanced, whereas the outflow of talent tended to be concentrated. The net inflow of marine research talent was active in the eastern and southern regions of China, whereas the net outflow of talent was active in the northeastern, central, and Beijing regions. The problem of high-intensity net inflow in the southern and eastern regions and high-intensity net outflow in the central and northeastern regions began alleviating. 4) The marine research talent mobility network exhibited an obvious core-periphery structure, and the "Matthew effect" was substantial. Qingdao was always at the core of the network, and there was a strong talent flow between the semi-peripheral and core cities. There was also strong relationship flows between them. Marine research talent in peripheral cities flows mainly to core and semi-peripheral cities. Overall, marine research talent is crucial for the development of coastal cities. Their mobility has a profound impact on both the source and destination cities. Therefore, it is necessary to formulate relevant policies based on the city's position within the marine research talent mobility network and optimize the allocation of marine talent, ultimately promoting the development of the marine economy.

China's Danxia landforms are characterized by their indicative red color. Portable ground object spectrometers are widely used owing to their small size, ease of operation in the field, rapid measurements, and simple operation. In this study, we analyzed the characteristic parameters of the reflection spectra of the Danxia rock wall surfaces (i.e., red surfaces, orange surfaces, and pure white spots) and different types of plant cover, as well as their quantitative relationships with color tones, using the visible-near-infrared (VNIR) reflectance spectra of the rock walls. The results indicate that the absorption depths and areas of the red and orange surface samples were highly correlated at 525 and 500 nm, as were the redness and orangeness of the samples. The redness and orangeness of the indoor and outdoor samples were relatively consistent with the absorption depth and area growth rates; however, the indoor samples had larger absorption depth and area values. The absorption depth and area of the pure white spots at 530 nm was highly correlated with redness, but the red surface and pure white spot spectra exhibited considerably different redness values, absorption depths, and absorption areas at 525–530 nm. Thus, these are advantageous parameters for distinguishing between the two surface types. The absorption positions of the red surfaces, orange surfaces, and pure white spots in the visible spectrum differed considerably, which is likely related to changes in the iron mineral types and contents present in the strata. Compared to the red surface absorption position at 525 nm, that of the orange surface shifted in the shortwave direction to 500 nm, which may be related to lower hematite and higher goethite contents. The absorption of the pure white spots at 430 nm may be caused by their pyrite content. The absorption depths of black, blocky, and green plants at 670 nm were considerably correlated with Normalized Difference Vegetation Index(NDVI). The NDVI values and absorption depths of the three plant types had widely differing range distributions, which can serve as a basis for distinguishing among the three plant types. The absorption depths of non-white spot and white spot plant coverings at 670 nm also increased with increasing NDVI values. The absorption positions of pure white spots in the visible spectrum were 430, 530, and 690 nm. After plants attached to the white spots, the 430 nm absorption position disappeared while that at 530 nm shifted in the shortwave direction. The absorption position at 690 nm was converted into that of chlorophyll. This study provides a reference for quantitatively investigating the color tones of the Danxia rock walls using VNIR reflectance spectroscopy.

Soil erosion is a major global environmental concern. Safeguarding soil and water resources requires a comprehensive understanding of erosion processes to proactively address and manage soil erosion. Accurately identifying key erosion features and implementing targeted soil and water conservation efforts are therefore imperative. Unmanned Aerial Vehicle (UAV) remote-sensing technology offers a novel method for advancing soil erosion research. As UAV applications in this field continue to progress, it is essential to systematically review and compare recent developments in soil erosion research between China and other countries so as to anticipate future research directions. In this study, we used the CiteSpace software to perform a bibliometric analysis of 871 Chinese and English articles published from 2008 to 2022 that were indexed in the Web of Science core database and China National Knowledge Infrastructure. Using statistical data from these publication databases, CiteSpace, Scimago Graphica, and ArcGIS, visual network maps were generated to summarize the fundamental characteristics and research hotspots related to UAV use in soil erosion research. The results indicate that the overall trend of UAV use in soil erosion studies is increasing. Countries such as the UK, France, Italy, Germany, and Australia have taken the lead, resulting in significant academic influences. Chinese researchers have built on mature research conducted abroad and are actively innovating, resulting in more publications and a growing academic impact. Globally, soil erosion research has predominantly focused on UAV photogrammetric technology and soil erosion mechanisms. Global research hotspots include the acquisition and integration of UAV and multi-source remote sensing data in erosion studies, innovative improvements in UAV-based erosion monitoring and information extraction algorithms, hydrological sediment connectivity and soil erosion model construction using UAV data as a source, and improvements to erosion disaster investigation, prevention, and comprehensive management of soil and water conservation based on UAV remote sensing data. Based on the current state of Chinese and international research, future studies should investigate data processing algorithms, establish precise evaluation and improvement methodologies, and strengthen multi-source and multi-scale data integration to establish the data foundation for understanding sedimentation mechanisms. Additionally, we recommend rationally arranging soil and water conservation measures based on erosion prevention mechanisms, as well as balancing erosion controls, ecological restoration, and sustainable production during the implementation of soil and water conservation efforts.