Significant Spatial Differences Research Articles

Bioregionalization of the subarctic Pacific based on phytoplankton phenology and composition

The subarctic Pacific is generally perceived as relatively homogeneous since the North Pacific Subpolar Gyre dominates the water circulation in the area. However, previous research showed significant spatial differences in phytoplankton abundance and community structure. This study aimed to identify regions associated with distinct phytoplankton phenology and composition to comprehensively describe the main phytoplankton variability patterns across the subarctic Pacific. To this end, satellite GlobColour time series observations and an extensive in situ phytoplankton pigment dataset were used in the analysis. Five bioregions were identified, based on the Self-Organized Mapping technique, using a greater than 20-year satellite data series. The bioregions in the open Pacific waters were dominated by green algae, haptophytes, and pelagophytes and were divided into the areas affected by the North Pacific Transition Zone and beyond. The other bioregions were defined around the Pacific basin margins where the diatom contribution was generally higher, with a particular distinction of waters surrounding the Kuril and the Aleutian Islands. Our bioregion designations allow for future evaluation of the processes controlling the physical and biological dynamics within each bioregion, which has direct implications for foraging conditions available to higher trophic levels, including potential food resource competition.

Geographical factor dominates spatial patterns of potential nitrate reduction rates in coastal wetland sediments in Fujian Province, China

Nitrate (NO3−) reduction is a key process governing the nitrogen (N) dynamics of coastal wetland sediments. Although the effects of environmental factors on the NO3− reduction mechanism in coastal wetland sediments have been examined in various studies, the effects of spatial variation in potential NO3− reduction processes in coastal wetland sediments and the factors driving geographical variation in these processes have not been widely examined. Here, we conducted research on surface sediment samples from four different vegetation types at six coastal wetland sites across two regions. We characterized potential rates of NO3− reduction processes (including denitrification (DF), anammox (ANA), and dissimilatory nitrate reduction to ammonium (DNRA)) using a15N tracer method. Additionally, we assessed the abundances of functional genes, and microbial community structure using high-throughput sequencing, and metagenomic sequencing. In six wetland sites, the contribution ranges of DF, ANA, and DNRA to NO3− reduction were 38.43%–55.69%, 31.33%–45.65%, and 5.26%–17.11%, respectively, and potential NO3− reduction was mainly driven by N removal via gaseous N (DF+ANA). Significant spatial differences were observed in the structure of bacterial and fungal microbial communities, suggesting that geographical distance has a major effect on microbial community structure. Environmental factors and Functional gene abundances were significantly related to potential NO3− reduction processes, and physicochemical properties had a stronger effect on potential NO3− reduction processes than gene abundances. Factors showing significant differences across regions were the main drivers of variation in potential NO3− reduction processes. Overall, our study showed that sediment substrates and geographical environmental factors rather than the abundance of functional genes and vegetation types were the main indicators of potential NO3− reduction activities in coastal wetlands.

Landform evolution of the Qilian Shan since 120 Ma revealed by apatite fission track data

The Cenozoic uplift of the Qilian Shan mountain range is intimately connected with the collision of the Indian and Eurasian plates, although the mechanism of deformation is still unclear due to the large distance between the Qilian Shan and the plate collision boundary. The first requirement if we are to determine this mechanism is to obtain the uplift process of the Qilian Shan range, which remains a matter of debate. We compiled apatite fission track data from previous studies of the Qilian Shan range to investigate the spatial and temporal disparities or similarities of the exhumation process. Most of the age-evolution profiles and thermo-modelling results show a low exhumation rate from 80 to 20 Ma, corresponding to shorter apatite fission track lengths, indicating a lower rate of erosion and lower relief across the whole Qilian Shan region. The results also reveal two stages of rapid exhumation: during the Cretaceous (120–80 Ma) and since the Miocene (20–0 Ma). The exhumation history of the Qilian Shan range shows no significant spatial difference and outward growth was limited at the southern and northern edges after 5 Ma. This temporal and spatial pattern for the exhumation of the Qilian Shan range suggests that there was probably no obvious uplift at the time of the initial collision of the Indian–Tibetan plates and support the proposal that the whole Qilian range has uplifted synchronously since 20 Ma.

Zooplankton community heterogeneity and trophic interactions in response to environmental drivers in a mesotidal estuary on the Brazilian equatorial margin—Lençóis Maranhenses National Park

Abstract This study emphasises the importance of environmental filters in the dynamics of the zooplankton community and the ecological relationships with phytoplankton in three zones of a tropical mesotidal estuary. Thus, sampling was carried out in six different locations strategically positioned along the Preguiças River estuary, with the following objectives: to characterise the abundance of zooplankton and, through this, determine changes in the community's α‐ and β‐diversity indices depending on variables environmental; to define environmental filters that affect the indicator species of ecosystem zones; and to identify the interaction between phytoplankton and zooplankton along the estuarine gradient. The zooplankton community contained 80 species, including 14 phyla, with Arthropoda being the most diverse, followed by Ciliophora and Mollusca. The class Copepoda stood out, with Paracalanus crassirostris, Pseudodiaptomus gracilis, and Oithona nana dominating the community. In total, 21 species were selected as indicators, including Temora turbinata in the coastal zone, Rhizodomus tagatzi in the mixing zone, and Moina micrura in the tidal river zone. The environmental heterogeneity showed significant spatial differences, with variations governed mainly by salinity, temperature, and suspended organic matter, which acted as the principal environmental filters. The coastal zone and mixing zone species demonstrated direct ecological relationships with the blooms of the diatoms Skeletonema costatum and Asterionellopsis glacialis, in which the abundance of zooplankton was favoured by their occurrence, denoting top‐down control of the trophic network. For the partitioning of β diversity, the turnover component was responsible for the diversity value due to environmental heterogeneity, which distinguished communities across zones. Our findings represent the first comprehensive investigation into the relationship between environmental heterogeneity and zooplankton within this tropical ecosystem, subject to mesotides. These discoveries are pivotal in identifying environments highly susceptible to degradation (low β diversity) and those acting as dispersal centres (high β diversity), thereby facilitating targeted conservation efforts and more efficient management of estuarine systems. Therefore, our results provide a crucial basis for the sustainable management of similar coastal ecosystems in different parts of the world.

Charging infrastructure assessment for shared autonomous electric vehicles in 374 small and medium-sized urban areas: An agent-based simulation approach

This research examines the use of Shared Autonomous Electric Vehicles (SAEVs) in 374 U.S. small and medium-sized urban areas, focusing on fleet and infrastructure needs through agent-based simulations. It assesses metrics such as fleet size, trips per vehicle, and charging station requirements, considering two charger types: Level 2 and Level 3. The findings show significant spatial differences in SAEV operations and infrastructure across these cities. Statistical analysis links these variations to regional road networks and travel patterns. The study finds Level 3 chargers more efficient, requiring fewer stations and enabling more trips per vehicle compared to Level 2 chargers. Furthermore, Level 3 chargers exhibit a greater number of trips per SAEV and a higher ratio of vehicles to charging stations. These findings highlight the significance of considering charging infrastructure characteristics to optimize SAEV fleet performance and promote sustainable transportation systems in urban areas. This study significantly contributes by identifying the spatial variation and correlates of the SAEVs' operational and charging infrastructural performance. Policymakers, urban planners, and transportation service providers can leverage these insights to design and implement effective charging infrastructure for SAEV fleets, thereby advancing the transition to cleaner and more efficient mobility solutions.

Spatial correlation between electricity generation and economic scale in Africa.

This study attempts to determine whether there is a spatial correlation between electricity generation and economic scale promoting coordinated development in Africa. We explore the spatial similarity and gray correlation degree between electricity generation and economic scale in Africa since the 21st century by adopting barycenter coupling and Gray Correlation Analysis method. We argue that there is a strong correlation between electricity generation and economic scale. Our findings indicate a significant spatial difference in electricity generation, mainly concentrated in Northern and Southern Africa. Furthermore, spatial pattern remains largely consistent over time, mirroring trends observed at the economic scale. Electricity generation and economic scale were concentrated in six countries- South Africa, Egypt, Algeria, Nigeria, Morocco, and Libya- and did not change significantly over time. A correlation analysis between electricity generation and the economic scale further confirmed this, with a linear coefficient of 0.907. Both the gravity centers of economic scale and electricity generation in Africa move farther in the north-south direction than in the East-West direction, with the former showing a Southwest-Northeast-Southwest track feature and the latter a Northeast-Southwest track feature. The spatial distribution of the gravity centers of electricity generation and the gravity centers of the economic scale in Africa are highly consistent; electricity generation highly correlates with the economic scale, consistent with the research conclusion obtained by the Gray Correlation Analysis method. This study suggests the coordinated development of electricity generation and economic scales in various African countries.

Does income inequality restrain marriage? A longitudinal study from the 35 large and medium-sized cities of China

In recent years, the continuous decline of marriage rate in Chinese cities has attracted significant attention. The study examined the impact of income inequality on marriage rates, and explored the mechanisms through which this relationship operates. Panel data of 35 large and medium-sized cities of mainland China from 2004 to 2019 were used to empirically test the theoretical hypothesis, finding the following results: Firstly, widening income inequality emerges as a crucial factor contributing to the decline in marriage rates within Chinese cities. Secondly, the impact of the income inequality on the marriage rate shows significant spatial and temporal differences in urban areas. Lastly, factors such as Internet penetration, urbanization and housing price are important channels for income inequality to affect the marriage rate. The objective of this study is to explain the decline of marriage rate in China's cities from the perspective of income distribution, and subsequently unveil the macro-level correlation between income inequality and marital behavior.

Effects of deep coal mining on groundwater hydrodynamic and hydrochemical processes in a multi-aquifer system: Insights from a long-term study of mining areas in ecologically fragile western China

The groundwater hydrodynamic and hydrochemical process of the multi-aquifer system will experience complicated and serious influence under deep coal mining disturbance. There is relatively little research that has integrated hydrodynamic and hydrochemical properties of groundwater to investigate the spatiotemporal distribution characteristics and evolution patterns of hydrogeochemistry and hydrodynamic information in deep multi-aquifer systems. The study of the groundwater hydrodynamic and hydrochemical spatiotemporal coupling response of multi-aquifer systems under the deep and special thick coal seam mining-motivated effect in ecologically fragile western mining areas is of great significance for the safe mining of coal resources and ecological environment protection. In this research, the hydrochemical analysis data composed of 218 groundwater samples from Tangjiahui coalfield, Northwest China with 1526 measurements and a 6-year (2016–2021) sampling period were collected for studying the hydrogeochemical spatiotemporal evolution process and governing mechanism of the multi-aquifer system using hierarchical cluster analysis, ion-ratio method, saturation index and multidimensional statistical analysis. Additionally, wavelet analysis and cross-wavelet coherence analysis were implemented to quantitatively recognize the spatiotemporal variation characteristics of hydrodynamic information and analyze the coherence relationships between time series. The results demonstrate that the hydrochemical characteristics exhibit significant spatial differences, while the temporal variation of hydrochemical characteristics in the Permian Shanxi Formation fractured sandstone aquifer (PSFFA), mine water (MW), and Ordovician karst limestone aquifer (OKA) is not significant. The water-rock interaction is the predominant control mechanism for the spatial evolution of hydrogeochemistry in the research area. Moreover, the large-scale mining of deep coal seams controls the type and degree of water-rock interactions by damaging the structure of aquifers and altering the hydrodynamic conditions of groundwater. The period from 2016 to 2021 exhibits multi-time scale characteristics in time series of precipitation, mine water discharge, and the water level of PSFFA and OKA. The mine water discharge has a positive correlation with the water level of PSFFA and OKA, whereas the significant period of precipitation and the water level of PSFFA coherence is not obvious. The research findings not only provide in-depth insights to protect the groundwater resources in water-shortage mining areas but also promote the secure mining of deep coal resources.

Distribution, sources and ecological risks of PAHs and n-alkanes in water and sediments of typically polluted estuaries: Insights from the Xiaoqing River

Seasonal water and sediment samples were collected from the Xiaoqing River estuary and the neighboring sea to study the spatial and temporal distributions, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The results showed significant spatial and temporal differences in the concentrations of PAHs and n-alkanes under the influence of precipitation, temperature, and human activities. The concentrations of PAHs in water were lower in the wet season than in the dry season, and those in sediments were higher in the wet season than in the dry season. The concentrations of n-alkanes were higher in the rainy season than in the dry season for both water and sediments. The spatial distributions of PAHs and n-alkanes were estuarine > offshore. The concentration ranges of ∑PAHs in water and sediments were 230.66–599.86 ng/L and 84.51–5548.62 ng/g, respectively, in the wet season and 192.46–8649.55 ng/L and 23.39–1208.92 ng/g, respectively, in the dry season. The proportion of three-ring PAHs in water (57.03% and 78.27% in the wet and dry seasons, respectively) was high, followed by two-ring PAHs (27.31% and 13.59% in the wet and dry seasons, respectively). The proportion of four-ring PAHs was higher in sediments (24.79% and 32.20% in the wet and dry seasons, respectively). The ecological risk of PAHs assessed using the toxicity equivalent quotient and risk quotient was at moderate to moderately high risk levels. The high concentration of n-alkane fraction C16 (611.65–75594.58 ng/L) in the water is indicative of petroleum or other fossil fuel inputs. The main peaks of n-alkanes in river sediments were C27, C29 and C31, indicating higher inputs of plant sources. The sediments in the estuary showed dominance of both short-chain C16 and long-chain C25–C31, indicating a combined input of higher plants and petroleum. The diagnostic ratios of PAHs and n-alkanes indicated that their sources were mainly oil/coal/biomass combustion and petroleum spills attributed to frequent vehicular, vessel and mariculture activities. Given the potential ecological risks of PAHs and n-alkanes in water and sediments, future studies should focus on their bioaccumulation and biotoxicity.

Impact of green finance on China's pollution reduction and carbon efficiency: Based on the spatial panel model

Green finance is an important means to promote the construction of ecological civilization and plays an important role in promoting the coordinated governance of pollution and carbon reduction. Based on the panel data of 277 cities at or above the prefecture level in China from 2006 to 2021, this study calculates the development level of green finance and the synergistic efficiency of pollution and carbon reduction. In addition, this study constructs the driving distance matrix. The study uses the spatial Durbin model to conduct an empirical test on the spatial effect and transmission mechanism of green finance on the synergistic efficiency of pollution and carbon reduction. Results show that: (1) A significant spatial difference exists between the development level of green finance and the collaborative efficiency of pollution and carbon reduction in China from 2006 to 2021. Moreover, the high-value areas of the two are concentrated in the eastern and southeast coastal areas, respectively; (2) The development of green finance has a positive spatial spillover effect on the collaborative efficiency of pollution and carbon reduction. The conclusion remains after a series of robustness tests, that is, green finance has a significant positive promoting effect on the collaborative efficiency of pollution and carbon reduction between the city and its neighboring cities; (3) The development of green finance can promote the improvement of the collaborative efficiency of pollution and carbon reduction by improving the level of green technology innovation and the advanced level of industrial structure, that is, the two play an intermediary effect. The conclusions of this study provide experience for an in-depth understanding of the environmental governance effect of green finance and actively guide financial resources to participate in the collaborative governance of carbon pollution.

Evaluation of Subseasonal-to-Seasonal (S2S) precipitation forecast performance from NMME-2 over Indonesia

Abstract Global Subseasonal-to-Seasonal (S2S) precipitation forecast was known to bridge the gap between weather and seasonal forecast, can be utilized as supporting information for decision-making related to hydrometeorological disaster mitigation activities. However, uncertainty in global models caused forecast performance can be different across regions and time periods. Therefore, it is important to evaluate forecast performance before utilizing the prediction result in any region. In this study, performance of probabilistic precipitation forecast from Multi-model Ensemble (MME) of three models in The North American Multi-Model Ensemble phase 2 (NMME-2) project was evaluated in Indonesia region based on two evaluation metrics: continuous ranked probability score (CRPS) and reliability diagram. The evaluation was conducted during the boreal summer (May–October) and boreal winter (November–April) periods, as well as during the active period of subseasonal climate variability phenomenon Madden-Julian Oscillation (MJO). Our result shows that S2S precipitation forecast from MME of CFSv2, CanCM4 and GEOS5 models are sufficiently accurate and reliable during the boreal summer period for Central Sumatra, Southern Sumatra, Southern Kalimantan, Java, Southern Sulawesi, and Southern Papua regions, with a range of CRPS values between 4-16 mm/7 days and a ‘perfect’ reliability category. There is no notable distinction in the performance of S2S precipitation forecast between the active and inactive events of the Madden-Julian Oscillation (MJO). The difference in CRPS values between these two periods is only around 0.8-1.2 mm/7 days, and there is no difference in reliability categories across Indonesia as a whole, nor significant spatial pattern differences.

Factors controlling spatiotemporal variability of soil carbon accumulation and stock estimates in a tidal salt marsh

Abstract. Tidal salt marshes are important contributors to soil carbon (C) stocks despite their relatively small land surface area. Although it is well understood that salt marshes have soil C burial rates orders of magnitude greater than those of terrestrial ecosystems, there is a wide range in accrual rates among spatially distributed marshes. In addition, wide ranges in C accrual rates also exist within a single marsh ecosystem. Tidal marshes often contain multiple species of cordgrass due to variations in hydrology and soil biogeochemistry caused by microtopography and distance from tidal creeks, creating distinct subsites. Our overarching objective was to observe how soil C concentration and dissolved organic carbon (DOC) vary across four plant phenophases and across three subsites categorized by unique vegetation and hydrology. We also investigated the dominant biogeochemical controls on the spatiotemporal variability of soil C and DOC concentrations. We hypothesized that subsite biogeochemistry drives spatial heterogeneity in soil C concentration, and this causes variability in total soil C and DOC concentrations at the marsh scale. In addition, we hypothesized that soil C concentration and porewater biogeochemistry vary temporally across the four plant phenophases (i.e., senescence, dormancy, green-up, maturity). To test these interrelated hypotheses, we quantified soil C and DOC concentrations in 12 cm sections of soil cores (0–48 cm depth) across time (i.e., phenophase) and space (i.e., subsite), alongside several other porewater biogeochemical variables. Soil C concentration varied significantly (p < 0.05) among the three subsites and was significantly greater during plant dormancy. Soil S, porewater sulfide, redox potential, and depth predicted 44 % of the variability in soil C concentration. There were also significant spatial differences in the optical characterization properties of DOC across subsites. Our results show that soil C varied spatially across a marsh ecosystem by up to 63 % and across plant phenophase by 26 %, causing variability in soil C accrual rates and stocks depending on where and when samples are taken. This shows that hydrology, biogeochemistry, and plant phenology are major controls on salt marsh C content. It is critical to consider spatiotemporal heterogeneity in soil C concentration and porewater biogeochemistry to account for these sources of uncertainty in C stock estimates. We recommend that multiple locations and sampling time points are sampled when conducting blue C assessments to account for ecosystem-scale variability.

The study of coevolution relationship among coastal marine economy, innovation, and ecology based on Chinese complex systems

Based on the complex system theory, this paper constructs a collaborative evolution model of marine economy, innovation and ecological protection. Findings show the MEIE orderliness shows an upward trend, and the adaptability of the system increase, however there are significant spatial difference. The synergistic relationship between economic development and innovation system is characterized by ‘bias’ and ‘mutual beneficial’. The Synergistics relationship between economic development-ecological protection system is ‘bias’. The Synergistics relationship between innovation-ecological protection system tend to be ‘bias’ or ‘inhibition’.

The effects of damming and dam regulation on a river–lake-aquifer system: 3D groundwater flow modeling of Poyang Lake (China)

Large numbers of dams are planned or constructed for hydroelectric power production, water supply, and flood control in many rivers around the world. While the social and environmental impacts of dams are now well-understood, there is little knowledge about the effects of dams on groundwater-surface water interactions in a complex lake–river-aquifer system. This study adopts a three-dimensional groundwater numerical model to quantify the potential impacts of dam construction, on regional groundwater flow system, exemplified by the proposed Poyang Lake Hydraulic Dam (PLHD) in China. Once implemented, the PLHD will regulate lake levels, artificially controlling the lake inundation area during the recession season (September-October) and the dry season (November-December). Modeling results indicated that the increase in lake infiltration induced by PLHD regulation would alter the regional water exchange pattern. The PLHD regulation will likely enhance the groundwater storage by 20.44 % in the general dry year (i.e., 2018), alleviating 78.1 % of the groundwater deficit in the extreme dry year (i.e., 2019). Additionally, the response of groundwater dynamics to the PLHD regulation exhibits significant spatial differences between the upstream and downstream areas of the dam, primarily depending on topographical changes. Overall, the PLHD regulation is most likely to impact groundwater levels across an area of approximately 5,700 km2, and the associated groundwater storage is anticipated to reach a stable state, under future long-term regulation. Our findings may guide policy-makers wishing to develop more suitable PLHD scheduling plans and floodplain protection strategies by providing reliable information regarding groundwater storage change and ecosystem succession.

Analysis of spatio-temporal changes in net primary productivity and their driving factors in ecological functional areas of the Yellow River Basin

The Yellow River Basin (YRB) is an important region for both ecological and economic growth in China, and a healthy and stable ecological environment is fundamental to achieving high-quality development. Investigating the spatio-temporal changs of vegetation carbon sinks in the YRB is necessary to improve understanding of the regional carbon cycle. This study analyzed the YRB using the Google Earth Engine (GEE) platform. The basin was divided into sections based on ecological function regionalization schemes. We applied Theil-Sen median trend analysis and Spearman correlation analysis, along with the lasso regression model, to examine the NPP's temporal and spatial patterns and its driving factors in these regions. The objective was to examine the NPP’ s temporal and spatial patterns and its driving factors in these regions, identifying commonalities within regions and differences between regions, while analyzing in a targeted manner the lack of vegetation carbon sequestration in ecological areas. This study highlighted the importance of ecological engineering in ecological civilization and carbon neutrality, providing scientific theoretical support and a decision-making basis for the realization of carbon neutrality. The research results indicate significant upward trends (p<0.001) in both the average annual NPP (AANPP) growth rate (57.98%) and the total annual NPP (TANPP) growth rate (41.9%) in the YRB from 2001 to 2020. The multi-year average NPP (MYANPP) exhibit a spatial distribution with high values in the south and low values in the north. The spatial distribution of NPP exhibits notable spatial aggregation and heterogeneity, where regions demonstrating improvement trends constitute 93.01% of the area, and approximately 79.73% of this region displays low volatility. A high-value area is concentrated in the Agroecological Zone of the Fenwei Basin (I-11), the Loess Plateau Agriculture and Grassland Ecological Zone (I-12), and the Qinba Mountains Deciduous and Evergreen Broad-leaved Forest Ecological Zone (I-15), with significant spatial differences. Temperature, precipitation, and forests are the foremost elements affecting NPP in the YRB, exhibiting positive correlations. Conversely, farmland displays negative correlations. Overall, NPP shows an increasing trend in all ecological function areas, and the NPP of the YRB shows a trend of improvement as a whole, as the ecological environment of the YRB has improved significantly.

Terrestrial and marine POC export fluxes estimated by 234Th–238U disequilibrium and δ13C measurements in the East China Sea shelf

The use of 234Th–238U disequilibrium has been widely employed to estimate the sinking flux of particulate organic carbon (POC) from the upper sea and ocean. Here, the deficits of 234Th relative to 238U in the water column and the carbon isotope signature (δ13C) of POC in the East China Sea (ECS) Shelf were measured, which was used to distinguish the fraction of marine and terrestrial POC export fluxes. In the ECS Shelf, very strong deficits of 234Th relative to 238U were observed throughout the water column, with 234Th/238U activity ratios ranging from 0.158 ± 0.045 to 0.904 ± 0.068 (averaging 0.426 ± 0.159). The residence times of particle reactive radionuclide 234Th (τTh–T) in the ECS shelf water varied between 9 and 44 days, which is significantly shorter than that in the continental slope area or the basin area. This phenomenon indicates that there is a more rapid particle scavenging process in the ECS shelf water compared to the continental slope and basin upper water. By applying a two-end-member mixing model based on the δ13C, the fraction of terrestrial POC was estimated to be 0 to 74% (mean: 30 ± 22%) and the fraction of marine POC was in the range of 25% to 100% (mean: 70 ± 22%). Fluxes of marine and terrestrial POC settling to the seafloor exhibited significant spatial differences among different stations, ranging from 11 to 129 mmol C/m2/day and from 2.6 to 38 mmol C/m2/day, respectively. The averaged terrestrial POC fluxes in the southern and northern ECS Shelf were similar (~ 21 to 24 mmol C/m2/day), while the marine POC fluxes in the north (86 ± 37 mmol C/m2/day) were approximately four times higher than those in the south (26 ± 20 mmol C/m2/day). Interestingly, the estimated export flux of both marine and terrestrial POC were approximately one order of magnitude higher than the previously reported burial fluxes of POC (ranging from 1.1 ± 0.1 to 11.4 ± 1.1 mmol C/m2/day) in the underlying bottom sediments, indicating that the majority (> 90%) of both terrestrial and marine POC exported from the upper water column are degraded in the sediments of the ECS Shelf. This “carbon missing” phenomenon can greatly be attributed to rapid decomposition by other processes (including microbial reworking, cross-shelf transport, and possible consumption by benthic organisms). Our findings highlight the dynamic nature of carbon cycling in the continental shelf and the need for further research to understand these processes and improve carbon budget assessments.

Analysis of Vegetation Environmental Stress and the Lag Effect in Countries along the “Six Economic Corridors”

Climate conditions have a significant impact on the growth of vegetation in terrestrial ecosystems, and the response of vegetation to climate shows different lag effects with the change in spatial pattern and category of the ecosystem. Exploring the interaction mechanism between climate and vegetation growth is helpful to promote the sustainable development of the regional ecological environment. Using normalized vegetation index (NDVI) and meteorological data, based on univariate linear regression and partial correlation analysis, this study explores the temporal and spatial pattern and change trend of vegetation cover in regions and node cities along the “six economic corridors”, and analyzes the environmental stress of vegetation growth and the lag effect of climate response. This study shows that there are great differences in the overall vegetation coverage along the “six economic corridors”. The vegetation coverage in Southeast Asia is the best and that in central and West Asia is the worst. The vegetation coverage in the study area shows an improvement trend, accounting for 39.6% of the total area. There are significant differences in the lag effect of vegetation response and the main climate factors affecting vegetation growth, which is related to the diversity of vegetation and climate characteristics. In this study, we selected regions along the “six economic corridors” that exhibit large latitude and altitude gradients, diverse climate types, and significant seasonal changes and spatial differences in climate conditions as our research areas. Additionally, we considered the impact of different regions and various types of vegetation on their response to climate change. This is of great significance for gaining a deeper understanding of the response mechanism of global climate change and vegetation ecology. Furthermore, our research can provide valuable information to support the ecological environment protection of different typical vegetation against extreme climates, ultimately contributing to the sustainable development of “the Belt and Road”.

From here to where: assessing the infrastructure financialization in urban China

PurposeInfrastructure financialization plays a critical role in infrastructure development and urban growth around the world. However, on the one hand, the existing research on the infrastructure financialization focuses on qualitative and lacks quantitative country-specific studies. On the other hand, the spatial heterogeneity and influencing factors of infrastructure financialization are ignored. This study takes China as a typical case to identify and analyze the spatial characteristics, development process and impact factors of infrastructure financialization.Design/methodology/approachTo assess the development and characteristics of infrastructure financialization in China, this study constructs an evaluation index of infrastructure financialization based on the infrastructure financialization ratio (IFR). This study then analyzes the evolution process and spatial pattern of China's infrastructure financialization through the spatial analysis method. Furthermore, this study identifies and quantitatively analyzes the influencing factors of infrastructure financialization based on the spatial Dubin model. Finally, this study offers a policy suggestion as a governance response.FindingsThe results demonstrate that infrastructure financialization effectively promotes the development of infrastructure in China. Second, there are significant spatial differences in China’s infrastructure financialization. Third, many factors affect infrastructure financialization, with government participation having the greatest impact. In addition, over-financialization of infrastructure has the potential to lead to government debt risks, which is a critical challenge the Chinese Government must address. Finally, this study suggests that infrastructure financialization requires more detailed, tailored,and place-specific policy interventions by the government.Originality/valueThis study not only contributes to enriching the knowledge body of global financialization theory but also helps optimize infrastructure investment and financing policies in China and provides peer reference for other developing countries.

A novel hybrid model combined with ensemble embedded feature selection method for estimating reference evapotranspiration in the North China Plain

The reference evapotranspiration (ETo) is a key parameter in achieving sustainable use of agricultural water resources. To accurately acquire ETo under limited conditions, this study combined the northern goshawk optimization algorithm (NGO) with the extreme gradient boosting (XGBoost) model to propose a novel NGO-XGBoost model. The performance of this model was evaluated using meteorological data from 30 stations in the North China Plain and compared with XGBoost, random forest (RF), and k nearest neighbor (KNN) models. An ensemble embedded feature selection (EEFS) method combined with the results from RF, XGBoost, adaptive boosting (AdaBoost), and categorical boosting (CatBoost) models is used to obtain the importance of meteorological factors in estimating ETo, and thereby determine the optimal combination of inputs to the model. The results indicated that by using the top 3, 4, and 5 important factors as input combinations, all models achieved high ETo estimation accuracy. It is worth noting that there were significant spatial differences in the estimation precisions of the four models, but the NGO-XGBoost model exhibited consistently high estimation precisions, with global performance indicator (GPI) rankings of 1st, and the range of coefficient of determination (R2), nash efficiency coefficient (NSE), root mean square error (RMSE), mean absolute error (MAE) and mean bias error (MBE) were 0.920–0.998, 0.902–0.998, 0.078–0.623 mm d−1, 0.058–0.430 mm d−1, and −0.254–0.062 mm d−1, respectively. Furthermore, the accuracy of the NGO-XGBoost model in estimating ETo varied across different seasons, which was more significantly affected by humidity and wind speed in winter. When the target station data was insufficient, the NGO-XGBoost model was trained by using the historical data from neighboring stations and still maintained a high precision. Overall, this study recommends a reliable method for estimating ETo, which provides a reference for accurately calculating ETo in the North China Plain in the absence of meteorological data.

Response of the copepod community to interannual differences in sea-ice cover and water masses in the northern Barents Sea

The reduction of Arctic summer sea ice due to climate change can lead to increased primary production in parts of the Barents Sea if sufficient nutrients are available. Changes in the timing and magnitude of primary production may have cascading consequences for the zooplankton community and ultimately for higher trophic levels. In Arctic food webs, both small and large copepods are commonly present, but may have different life history strategies and hence different responses to environmental change. We investigated how contrasting summer sea-ice cover and water masses in the northern Barents Sea influenced the copepod community composition and secondary production of small and large copepods along a transect from 76°N to 83°N in August 2018 and August 2019. Bulk abundance, biomass, and secondary production of the total copepod community did not differ significantly between the two years. There were however significant spatial differences in the copepod community composition and production, with declining copepod abundance from Atlantic to Arctic waters and the highest copepod biomass and production on the Barents Sea shelf. The boreal Calanus finmarchicus showed higher abundance, biomass, and secondary production in the year with less sea-ice cover and at locations with a clear Atlantic water signal. Significant differences in the copepod community between areas in the two years could be attributed to interannual differences in sea-ice cover and Atlantic water inflow. Small copepods contributed more to secondary production in areas with no or little sea ice and their production was positively correlated to water temperature and ciliate abundance. Large copepods contributed more to secondary production in areas with extensive sea ice and their production was positively correlated with chlorophyll a concentration. Our results show how pelagic communities might function in a future ice-free Barents Sea, in which the main component of the communities are smaller copepods, and the secondary production they generate is available in energetically less resource-rich portions.