Intensive Human Activities Research Articles

Response of wildlife communities to human activities in the distribution area of the North China Leopard

Currently, human activities are among the most important factors affecting the distribution of wildlife, and conservationists around the world are working to uncover the true impact of human activities on wildlife. With the rapid disappearance of tigers and wolves in North China in recent decades, leopards have become the only top predators. However, the responses of wildlife, including leopards, to human activities in North China leopard distribution areas remain unknown. This study systematically quantified human disturbance and village distance as gradient variables to measure the intensity of human activities, and community threshold analysis was used to analyze the threshold response of wildlife communities to human activities in the North China leopard distribution area. The results showed that human disturbance and village distance had threshold effects on the wildlife community. There were different response thresholds for 19 wildlife species, including leopards, to human activities. The findings show that reasonable control of human activity intensity according to the leopard threshold response (0.14 times/day) may be beneficial to the distribution of most wildlife. This result will help to clarify the role of leopards as umbrella species in wildlife conservation. The study of ecological thresholds can provide reliable results for the development of scientific management policies for wildlife conservation.

Vegetation Greening and Its Response to a Warmer and Wetter Climate in the Yellow River Basin from 2000 to 2020

Vegetation greening is time-dependent and region-specific. The uncertainty of vegetation greening under global warming has been highlighted. Thus, it is crucial to investigate vegetation greening and its response to climate change at the regional scale. The Yellow River Basin (YRB) is a vital ecological barrier in China with high ecological vulnerability and climatic sensitivity. The relationship between vegetation greening and climate change in the YRB and the relative contribution of climate change remain to be explored. Using the Enhanced Vegetation Index (EVI) and meteorological observation data, the spatiotemporal patterns of vegetation greening across the YRB in response to climate change at the basin and vegetation sub-regional scales from 2000 to 2020 were analyzed. The impact of human activities on regional greening was further quantified. Results showed that approximately 92% of the basin had experienced greening, at average annual and growing season rates of 0.0024 and 0.0034 year–1, respectively. Greening was particularly prominent in the central and eastern YRB. Browning was more prevalent in urban areas with a high intensity of human activities, occupying less than 6.3% of the total basin, but this proportion increased significantly at seasonal scales, especially in spring. Regional greening was positively correlated with the overall warmer and wetter climate, and the partial correlation coefficients between EVI and precipitation were higher than those between EVI and temperature. However, this response varied among different seasonal scales and vegetation sub-regions. The combined effects of climate change and human activities were conducive to vegetation greening in 84.5% of the YRB during the growing season, while human activities had a stronger impact than climate change. The relative contributions of human activities to greening and browning were 65.15% and 70.30%, respectively, mainly due to the promotion of ecological rehabilitation programs and the inhibition of urbanization and construction projects.

Occurrence, Source Apportionment, and Ecological Risk of Typical Pharmaceuticals in Surface Waters of Beijing, China.

Various studies have shown that the heavy use of pharmaceuticals poses serious ecological risks, especially in metropolitan areas with intensive human activities. In this study, the spatial distribution, sources, and ecological risks of 29 pharmaceuticals in 82 surface waters collected from the North Canal Basin in Beijing were studied. The results showed that the pharmaceutical concentrations ranged from not detected to 193 ng/L, with ampicillin being undetected while ofloxacin had a 100% detection frequency, which indicates the widespread occurrence of pharmaceutical pollution in the North Canal Basin. In comparison with other freshwater study areas, concentrations of pharmaceuticals in the North Canal Basin were generally at moderate levels. It was found that pharmaceutical concentrations were always higher in rivers that directly received wastewater effluents. Source analysis was conducted using the positive matrix factorization model. Combining the spatial pollution patterns of pharmaceuticals, it has been found that wastewater effluents contributed the most to the loads of pharmaceuticals in the studied basin, while in suburban areas, a possible contribution of untreated wastewater was demonstrated. Risk assessment indicated that approximately 55% of the pharmaceuticals posed low-to-high ecological risks, and combining the results of risk analyses, it is advised that controlling WWTP effluent is probably the most cost-effective measure in treating pharmaceutical pollution.

Multiscale Analysis for Identifying the Impact of Human and Natural Factors on Water-Related Ecosystem Services

Accurately identifying and obtaining changes in ecosystem drivers and the spatial heterogeneity of their impacts on ecosystem services can provide comprehensive support information for ecological governance. In this study, we investigate the changes in the relationship between human and natural factors and water-related ecosystem services (WESs) in different sub-watersheds across various time periods, focusing on four aspects: single-factor effect, nonlinear effect, interactive effects, and spatial characteristics. Taking the southern basins, which have complex topographic, climatic, and economic characteristics, as a study area, the study area was divided into four sub-basins with different characteristics. WESs of water yield, soil conservation, and water purification were quantified using the InVEST model for five periods from 2000 to 2020, and the OPGD and MGWR models were integrated to assess the impacts of 15 factors on WESs and their spatial characteristics. The results show the following: (1) After comparing the data over multiple time periods, climate factors such as precipitation (0.4033) are the primary factors affecting WESs in the southern basins, and human factors such as construction area (0.0688) have a weaker influence. The direct impact of human factors on WESs is not significant in the short term but increases over time. (2) Different sub-watersheds have different impacts on WESs. For instance, human activity intensity (0.3518) is a key factor affecting WESs in the Inward Flowing Area, while precipitation is the primary factor influencing WESs in other sub-watersheds. (3) Influencing factors and WES changes are often nonlinearly correlated; however, once a certain threshold is exceeded, they may have adverse impacts on WESs. (4) When a single factor interacts with other factors, its explanatory power tends to increase. (5) Compared to traditional methods, the estimation accuracy of MGWR is higher. Intense human activities can adversely affect WESs, while abundant precipitation creates favorable conditions for the formation of WESs. Therefore, integrating long-time-series multi-remote sensing data with OPGD and MGWR models is suitable for identifying and analyzing the driving mechanisms of human and natural factors that influence changes in WESs. Against the backdrop of global change, elucidating the driving factors of ecosystem services can provide crucial insights for developing practical policies and land management applications.

Analysis of Vegetation NDVI Changes and Driving Factors in the Karst Concentration Distribution Area of Asia

Due to the special nature of karst landforms, quantification of their vegetation dynamics and their underlying driving factors remains a formidable challenge. Based on the NDVI dataset, this study uses principal component analysis to extract comprehensive factors and utilizes an optimized parameter-based geographical detector and geographically weighted regression models to assess the explanatory capacity of comprehensive factors concerning the spatial differentiation of vegetation change. The results of this study revealed the following: (1) In terms of temporal and spatial vegetation changes, the Asian karst concentrated distribution area (AKC) displayed overall stability and an increasing trend between 2000 and 2020. Notably, the northern (Southwest China) karst region experienced the most substantial vegetation increase, with increased areas exceeding 70%, primarily concentrated in the provinces of Guizhou and Guangxi. In contrast, the southern (Indochina Peninsula) karst region, particularly in Cambodia, Laos, and Vietnam (CLV), exhibited a significant decreasing trend, with decreased areas exceeding 30%. (2) By analyzing the driving factors affecting vegetation change, vegetation changes exhibited distinct spatial differentiations, along with positive and negative effects. Human factors, including human activity intensity, urban economic development, and agricultural economic development (explanatory power and local R2 were both greater than 0.2), exerted a more significant impact on vegetation change in the AKC than natural factors such as thermal conditions, water conditions, and soil conditions. This impact was positive in Southwest China but inhibited in the Indochina Peninsula, particularly within the CLV karst area. Notably, the interaction between natural and human factors greatly enhanced their impacts on vegetation changes. These results provide valuable insights into vegetation changes and their driving mechanisms, which are crucial for preserving the stability of delicate karst ecosystems and facilitating vegetation recovery.

Using vulnerability assessment to characterize coastal protection benefits provided by estuarine habitats of a dynamic intracoastal waterway.

The existence of coastal ecosystems depends on their ability to gain sediment and keep pace with sea level rise. Similar to other coastal areas, Northeast Florida (United States) is experiencing rapid population growth, climate change, and shifting wetland communities. Rising seas and more severe storms, coupled with the intensification of human activities, can modify the biophysical environment, thereby increasing coastal exposure to storm-induced erosion and inundation. Using the Guana Tolomato Matanzas National Estuarine Research Reserve as a case study, we analyzed the distribution of coastal protection services-expressly, wave attenuation and sediment control-provided by estuarine habitats inside a dynamic Intracoastal waterway. We explored six coastal variables that contribute to coastal flooding and erosion-(a) relief, (b) geomorphology, (c) estuarine habitats, (d) wind exposure, (e) boat wake energy, and (f) storm surge potential-to assess physical exposure to coastal hazards. The highest levels of coastal exposure were found in the north and south sections of the Reserve (9% and 14%, respectively) compared to only 4% in the central, with exposure in the south driven by low wetland elevation, high surge potential, and shorelines composed of less stable sandy and muddy substrate. The most vulnerable areas of the central Reserve and main channel of the Intracoastal waterway were exposed to boat wakes from larger vessels frequently traveling at medium speeds (10-20 knots) and had shoreline segments oriented towards the prevailing winds (north-northeast). To guide management for the recently expanded Reserve into vulnerable areas near the City of Saint Augustine, we evaluated six sites of concern where the current distribution of estuarine habitats (mangroves, salt marshes, and oyster beds) likely play the greatest role in natural protection. Spatially explicit outputs also identified potential elevation maintenance strategies such as living shorelines, landform modification, and mangrove establishment for providing coastal risk-reduction and other ecosystem-service co-benefits. Salt marshes and mangroves in two sites of the central section (N-312 and S-312) were found to protect more than a one-quarter of their cross-shore length (27% and 73%, respectively) from transitioning to the highest exposure category. Proposed interventions for mangrove establishment and living shorelines could help maintain elevation in these sites of concern. This work sets the stage for additional research, education, and outreach about where mangroves, salt marshes, and oyster beds are most likely to reduce risk to wetland communities in the region.

Anthropogenic Impact on the Terrestrial Environment in the Lake Dian Basin, Southwestern China during the Bronze Age and Ming–Qing period

The role of human activity in shaping the terrestrial environment has been a core scientific issue of interest across various disciplines. However, it remains unclear whether there are significant differences in the patterns of the anthropogenic impact on the terrestrial environment in terms of spatial and temporal dimensions, and we are yet to identify the underlying factors that have driven it. Here, we present an analysis of sporopollen and geochemical proxies from a section of the Anjiangbei site (AJB) on the Yunnan Plateau, spanning the Ming–Qing period, in order to explore the spatio-temporal variation in the anthropogenic impact on the terrestrial environment in the Lake Dian basin. Integrating the reported multidisciplinary evidence, we aim to reveal the influencing factors of anthropogenic impact. Our results show that there were remarkable differences in anthropogenic impact on the terrestrial environment in the Lake Dian basin between the Late Bronze Age and the Ming–Qing period. Changes in crop vegetation and the forest were all affected by human activity in the Lake Dian basin during the two periods, and were more evident during the Ming–Qing period. The heavy metal pollution in the soil was obvious during the Ming–Qing period. The increase in the intensity of human activity, especially the rise in population, could be attributed to changes in the hydrological environment in the Lake Dian basin during the Late Bronze Age and to geopolitical change during the Ming–Qing period. This study reveals the different patterns in human impact on the terrestrial environment in the Lake Dian basin during the Late Bronze Age and the Ming–Qing period, providing new evidence to enable a deeper understanding of past human–environment interactions on the Yunnan Plateau.

Remotely Sensed and Field Data for Geomorphological Analysis of Water Springs: A Case Study of Ain Maarrouf

Tabular Middle Atlas of Morocco holds the main water reservoir that serves many cities across Morocco. Dolomite and limestone are the most dominant geologic formations in this region in which water resources are contained. The recent studies conducted to evaluate the quality of this water suggest that it is very vulnerable to pollutants resulting from both anthropogenic and natural phenomenon. High and very high-resolution satellite imagery have been used in an attempt to gain a better understanding of this karstic system and suggest a strategy for its protection in order to reduce the impact of these phenomenon. Based on the surface reflectance of land cover benchmarks, the karstic system has been horizontally delineated, as well as regions with intense human activities. Using band combination in the portion of the infrared, shortwave infrared, and visible parts of the electromagnetic spectrum, we identified bare lands which have been interpreted as carbonate rocks, clay minerals, uncultivated fields, basalts rocks, and built-up areas. Other classes such as water and vegetation have been identified. Carbonate rocks have been identified as areas with a high rate of water infiltration through their fracture system. Using a Sobel operator filter, these fractures have been mapped and their results have revealed new and existing faults in two major fracture directions, NE-SW and NW-SE, where NE-SW is the preferable pathway for surface water infiltration towards the groundwater reservoir, while the NW-SE direction drains groundwater from the Cause to the basin of Saiss. Over time, the infiltration of surface water through fractures has contributed to a gradual erosion of the carbonate rocks, which in turn developed karst landforms. This karst system is vulnerable due to the flow of pollutants in areas with shallow sinkholes. Using GDEM imagery, we extracted karst depressions, and their analysis shows that they are distributed along the fracture system and many of them were located on curvilinear or linear axes along the NE-SW fracture direction. We found also dolines scattered in areas with a high intensity of fractures. This distribution has been validated by both on-the-ground measurements and very high-resolution satellite images, and depressions of different forms and shapes dominated by dolines, poljes, lapiez, and avens have been identified. We also found many water springs with a highly important water output, such as the Ain Maarrouf water spring. The aim of this study is to enhance the understanding of the hydrogeological system of TMA, to improve the existence of the fracture database in the Cause of Agourai, and to establish a new morpho-structural picture of the Ain Maarrouf water spring.

Simulation and Application of Water Environment in Highly Urbanized Areas: A Case Study in Taihu Lake Basin

In the wake of frequent and intensive human activities, highly urbanized areas consistently grapple with severe water environmental challenges. It becomes imperative to establish corresponding water environment models for simulating and forecasting regional water quality, addressing the associated environmental risks. The distributed framework water environment modeling system (DF-WEMS) incorporates fundamental principles, including the distributed concept and node concentration mass conservation. It adeptly merges point source and non-point source pollution load models with zero-dimensional, one-dimensional, and two-dimensional water quality models. This integration is specifically tailored for various Hydrological Feature Units (HFUs), encompassing lakes, reservoirs, floodplains, paddy fields, plain rivers, and hydraulic engineering structures. This holistic model enables the simulation and prediction of the water environment conditions within the watershed. In the Taihu Lake basin of China, a highly urbanized region featuring numerous rivers, lakes and gates, the DF-WEMS is meticulously constructed, calibrated, and validated based on 26 key water quality monitoring stations. The results indicate a strong alignment between the simulation of water quality indicators (WQIs) and real-world conditions, demonstrating the model’s reliability. This model proves applicable to the simulation, prediction, planning, and management of the water environment within the highly urbanized watershed.

Unraveling carbon stock dynamics and their determinants in China's Loess Plateau over the past 40 years

Synergies and trade-offs among land use and land covers (LULCs) pose considerable uncertainties in achieving the dual carbon goals for China's Loess Plateau (CLP). In this context, we unraveled the carbon stock dynamics induced by land use and land cover change (LUCC) in the CLP over the past 40 years using the satellite-derived annual LULC maps and the InVEST model. Then, mixed measures were employed to quantify the global and local responses of the carbon stock dynamics to both natural and anthropogenic factors. We found that approximately a total of 5.58 × 109 Mg of carbon was stored in the CLP's ecosystems in 2019. Chronologically, the total carbon stock showed a slight decrease in the CLP from 1980 to 2019 due to the extensive LUCCs linked to socioeconomic activities. Specifically, the total carbon density loss rate accelerated in urban–rural-wild continuum (RUWC) types with higher human activity intensity, such as villages and urban, while it decelerated in woodlands, and croplands, where the human activity intensity is lower. Moreover, the total carbon density gain rate in wildlands was accelerating. Finally, we revealed that the carbon stock dynamics in the CLP over the past 40 years were primarily influenced by socioeconomic variables and have responded diversely to the drivers in space.

Biogenic element driving mechanism in the occurrence of Chinese coastal eco-environmental disasters and regulation for ecological environment health.

In recent decades, China's coastal ecological environment has undergone significant changes under multiple pressures such as climate change and high intensity of human activities. The occurrence and scale of harmful algal blooms represented by the red tide and the green tide are increasing rapidly. Moreover, environmental problems such as hypoxia and acidification in seawater have become increasingly prominent. It is urgent to find out the occurrence mechanism and prevention measures of marine eco-environmental disasters. Therefore, we explained the connotation of the concept of "marine eco-environmental disaster" for the first time, and systematically interpreted the biogenic element driving mechanisms in the occurrence of eco-environmental disasters in China nearshore area in the aspects of exogenous input of nutrients, the mineralization and decomposition of marine organic matters and nutrient regeneration, as well as the abnormal nutrient structure in offshore waters. We pointed out that the drastic increases of terrigenous nutrient discharge caused by enhancing human activities, together with the complex biogeochemical cycle process after biogenic elements entering the sea, led to the frequent occurrence of coastal eco-environmental disasters. On this basis, combined with the latest research progress in this field, we put forward the regulatory schemes for coastal ecological environment health based on the controlling of seawater biogenic element. That is, based on land-sea integration strategy, the reduction of land-source pollutants, especially inorganic nitrogen from land, coastal zone and into the sea, and the normalization of nutrient structure in coastal seawater through artificial regulation technology, are the key points to reduce and control the occurrence of disasters and improve the quality of the coastal ecosystems.

The quantifying, mapping, and risk analysis of human-related stressors in the high seas.

Objectives: Marine biodiversity and ecosystem services in the high seas are threatened by numerous stress factors caused by human activities, including global shipping, high-sea fishing, marine plastic pollution, and anthropogenic climate change. Socioeconomic factors are one of the criteria for the establishment of area-based management tools in the high seas for marine biodiversity conservation beyond national jurisdiction. The aim of the work is to propose a spatiotemporal approach to identify risks from marine human activities and recommendations for high seas governance. Methods: Data related to human activities from 2014 to 2022 were used to calculate the distribution and changes of human-related stressors, and the risk to marine biodiversity in the high seas caused by human activities. Results: The North Atlantic, Philippine Sea, Arabian Sea, Bay of Bengal, and East Central Atlantic show high and increasing intensities of human-related stressors, and are therefore particularly at need for the protection and conservation of marine biodiversity. Risks from human activities vary within the marine areas that are prioritized for biodiversity protection. The study recommends that the designation of high seas protected areas should take into account the types of risks to which the different marine areas are exposed, and that the high seas protected areas should be established gradually. At the same time, appropriate management measures should be formulated according to the intensity of human activities in the different marine areas. Conclusions: Quantifying and classifying the risk from human-related stressors could help identify solution for the protection and conservation and facilitate the marine spatial planning, establishment area based management tools, including marine protected areas in the high seas.

Water conservation pattern of Fangcheng River Basin in Beibu Gulf and its response to precipitation.

Assessing the spatiotemporal patterns of watershed water conservation under the influence of the South Asian monsoon climate and its response to precipitation is essential for revealing the evolving patterns of water conservation under different temporal scales. Following the principles of water balance and using the Soil and Water Assessment Tool (SWAT) model, we investigated the spatiotemporal patterns of water conservation and its response to precipitation in the Fangcheng River Basin of Beibu Gulf. The results showed that water conservation in Fangcheng River Basin calculated by SWAT model were 1637.4 mm·a-1, accounting for 50.7% of the mean annual precipitation. The variation of water conservation in different sub-basins was obviously different. Sub-basins with high forest coverage and steep slopes exhibited higher water conservation, while sub-basins with other land use types (such as cropland and grassland), gentle slopes, and intense human activities showed lower water conservation. At the monthly scale, both water conservation and its variation showed similar response characteristics to precipitation in the basin. The response of water conservation variation to sub-precipitation events could be classified into two types. For the short-term rainfall events (duration≤2 days), water conservation variation showed a linear relationship. For the medium to long-term rainfall events (2 days<duration≤10 days), water conservation variation showed a nonlinear curve, being influenced mainly by processes such as evapotranspiration. High-frequency short-duration precipitation events were more conducive to increasing ecosystem water conservation compared to the long-duration precipitation events.

Intense Human Activities Induce the Dynamic Changes of Interaction Pattern Between Karst Water‐Quaternary Groundwater in the Basin‐Mountain Coupling Belt Over the Past 60 Years

AbstractKarst water are important for water supply and ecological protection. However, climate changes and human activities have caused severe water supply crisis. The Jinci spring, one of the famous karst springs in China, is located at the basin‐mountain coupling belt and dried up since 1994. This study integrated hydrogeological conditions, water table logs, hydrogeochemistry, multiple isotopes, and numerical modeling to understand dynamic changes of interaction pattern between karst water‐Quaternary groundwater response to human activity in the basin‐mountain coupling belt over the past 60 years. Our investigation indicated that under natural conditions (1960s), karst water discharges as springs and laterally recharges into Quaternary groundwater at the fault area. In the 1980s, overexploitation caused a significant reduction in spring discharge and a decline in karst water levels, especially in coal mining areas. Further declines in water levels and mixing recharge by karst water‐Quaternary groundwater were observed in the 2000s, which were eased in 2018. Calculations both by oxygen isotope and models indicated that contribution of Quaternary groundwater to Jinci spring ranged from 11.8% to 42.1%, with the highest in the 2000s. Evidenced by multiple isotopes, the recharging of karst water‐Quaternary groundwater varied spatially along the belt in 2018, with delayed water level elevation in coal mining and heavy groundwater exploration areas. This study demonstrated that artificial disturbance fundamentally affected the karst water‐Quaternary groundwater flow and water exchange between them. Precautions should be taken when evaluating global water resources changes, in view of the dynamic interaction between the karst water‐Quaternary groundwater spatially and temporally.

Spatio-Temporal Evaluation of Water Resources System Resilience and Identification of Its Driving Factors in the Yellow River Basin

Water resources are crucial for the development of ecosystems and humanity. The Yellow River Basin (YRB), as an important ecological area in China, is facing significant challenges in ecological protection and high-quality development due to global climate change and intense human activities. In order to alleviate the water resources crisis in the YRB, it is necessary to calculate the resilience of the water resources system and identify the main influencing factors. This paper considered the factors of water resources, social economy, and ecological environment, then constructed an evaluation framework of the water resources system resilience (WRSR) from three aspects: resistance, restoration, and adaptability. Taking nine provinces along the YRB as a case study, the WRSR was measured by using the entropy weight TOPSIS model, and its driving factors were analyzed with Geographical Detectors (GD). The results showed that: (1) From 2010 to 2022, the WRSR in the Yellow River Basin and various provinces was showing a fluctuating increasing trend, in which Ningxia had the highest average WRSR (0.646), while Shanxi had the lowest (0.168). (2) From three dimensions, the development trends of resistance, restoration, and adaptability in the YRB and various provinces from 2010 to 2022 were relatively stable. Shandong’s resistance level far exceeded that of other provinces, having the highest average resistance value (0.692), and Ningxia had the highest average value of restoration (0.827) and adaptability (0.711). However, Gansu had the lowest average value of resistance (0.119), Sichuan had the lowest average value of restoration (0.097), and Shandong had the lowest average value of adaptability (0.110). (3) In terms of impact factors, the development and utilization rate of water resources (C13) and the development and utilization rate of surface water resources (C14) in the restoration subsystem consistently ranked in the top two of influencing factors. Similarly, the water consumption per 10,000 yuan of GDP (C26) in the adaptability subsystem consistently ranked within the top ten. On the other hand, the natural population growth rate (C6) in the resistance subsystem, as well as the impact of ammonia nitrogen emissions (C9) and total precipitation (C2) in wastewater, exhibited an upward trend. Based on these, this paper provides relevant suggestions for improving the WRSR in the YRB.

Landscape ecological risk assessment across different terrain gradients in the Yellow River Basin

The Yellow River Basin is an important ecological barrier zone in China, and the landscape pattern has changed greatly due to intense human activities. It is of great significance to explore the dynamic forecasting of ecological risk based on terrain gradient for the ecological security of the Yellow River Basin. In this study, the distribution characteristics of ecological risk from 2000 to 2040 are evaluated by CA-Markov and ERI models. We put forward a new method of landscape ecological risk assessment based on terrain gradient and further analyzed the relationship between ecological risk and terrain index. The results showed that the proportion of the cultivated land and the grassland in the Yellow River basin is more than 73%, with the largest dynamic change in 2020. The ecological risk in the study area showed a spatial pattern of “high in the northwest and southwest, low in the east and south-central.” During the study period, the overall ecological risk showed a decreasing trend, and the high risk was reduced by four times. The future ecological risk of all terrain gradient will show a decreasing trend, the high risks mainly occurred in areas with “flat terrain with low terrain gradient and low vegetation coverage.” This study will provide a new perspective for the dynamic forecasting of ecological risk and the analysis of the change of ecological risk through terrain gradients.

Diurnal variation in the urban thermal environment and its relationship to human activities in China: a Tencent location-based service geographic big data perspective.

The main factor of the formation and deterioration in China's urban thermal environment is human activity, which is difficult to describe and measure. A new perspective on the effect of human activity on the urban thermal environment can be obtained by examining the interaction between location-based service (LBS) data and the urban thermal environment in China. However, relevant research is still limited. In this study, we used Tencent LBS data, Terra/Aqua MODIS land surface temperature (LST) data, and land use data to investigate the relationship between LBS and the urban thermal environment, specifically the LST and surface urban heat island intensity (SUHII) across China and its provinces. Our results showed that (1) in summer, the heat island effect was an issue in 94% of the urban areas in China, which was worse during the day. The high- and low-value periods of LBS data on a given day coincided with the acquisition times of MODIS LST products during the day and at night, respectively. (2) During both the day and at night, there was a significant connection between LBS data and the urban thermal environment in China. The highest correlation coefficient (r) between LBS data and the LST could reach 0.55 (p < 0.01) at the provincial level, and the highest correlation coefficient (r) between LBS data and the SUHII could reach 0.78 (p < 0.01) at the provincial level. (3) The urban thermal environment diurnal difference and LBS data exhibited a significant relationship. The ΔLBS diurnal differences were significantly positively related to the SUHII diurnal differences in China. The overall study findings revealed that LBS data constitute an important parameter to represent the human activity intensity when investigating the formation of the urban thermal environment in China.

Appropriate stoichiometric ratios of dissolved organic carbon and nitrate can trigger a transition in nitrate removal in groundwater around plateau lakes, Southwest China

Increasing dissolved organic carbon (DOC) in groundwater as a carbon source for microorganisms that stimulate nitrate attenuation is considered a sustainable strategy to mitigate nitrate pollution in groundwater. However, little is known on the stoichiometric ratio of DOC and nitrate required in groundwater nitrate reduction processes, which has become an obstacle for evaluating the current status of DOC limitations on nitrate reduction. Here, the NO3—-N and DOC concentrations in groundwater around 8 plateau lakes were investigated, and a microcosm experiment was performed to elucidate the effects of different DOC:NO3—-N levels in groundwater on NO3—-N reduction, and the current status of DOC limitations on groundwater NO3—-N reduction around 8 lakes was further evaluated. The results indicated that nearly 41 % of the groundwater NO3—-N concentrations exceeded the WHO threshold for drinking water (11.3 mg L−1) and 79 % of the groundwater DOC concentrations exceeded 5 mg L−1. The differences in groundwater NO3—-N and DOC concentrations among the 8 lakes were controlled by the intensity of agricultural and human activities and hydrogeological background. The stoichiometric ratio of DOC:NO3—-N regulated the NO3—-N reduction process, and groundwater NO3—-N accumulation rate appeared to become limited and sharply decreased when the DOC concentration was approximately 10 mg L−1 or when the DOC:NO3—-N ratio was close to 1:1, and the DOC:NO3—-N ratio threshold for limiting the NO3—-N reduction process was approximately 2.25. Based on this threshold, >33 %–86 % of the groundwater samples around the 8 plateau lakes were strongly limited in the reduction of groundwater NO3—-N due to a lack of sufficient DOC provides energy for heterotrophic microorganisms. Additionally, we highlight that the sustainable strategy of increasing DOC to stimulate groundwater NO3— attenuation should be combined with short-term strategies to jointly coordinate and control groundwater NO3— pollution.

Taxonomic and chorological novelties in Blakea (Melastomataceae: Pyxidantheae) from Peru with a list of species for the country

Seven new Peruvian species of Blakea are described and illustrated here: Blakea eden, Blakea quinta, Blakea wilderi and Blakea yumi from the Department of Amazonas, Blakea pavida and Blakea rojasiae from the Departments of Amazonas and Cajamarca, and Blakea leoniae from the Departments of Amazonas and San Martin. Following IUCN criteria, we propose that most species should be considered as Endangered (EN) but for B. pavida, B. quinta and B. yumi, that should be recognized as Critically Endangered (CR) due to their restricted distributions and the intense ongoing human activity (agriculture and livestock) in their habitats. Additionally, we provide notes on the new records and species that have been published since Brako &amp; Zarucchi’s checklist of the Peruvian flora in 1993, including the lectotypifications of Blakea brasiliensis, B. nareliana, and Topobea pittieri (B. henripittierii). Blakea gracilis and B. parvifolia are suggested to be excluded from Peru. Based on this, we present a list of 33 Blakea species currently accepted for Peru, 14 of which are endemic.

Temporal patterns and driving factors of sediment carbon, nitrogen, and phosphorus stoichiometry in a eutrophication plateau lake

Stoichiometry determines the key characteristics of organisms and ecosystems on a global scale and provides strong instructions on the fate of sediment carbon, nitrogen, and phosphorus (C-N-P) during the sedimentation process, contributing to the Earth's C-N-P balance. However, the mechanisms underlying C–N–P stoichiometry in response to intensive human activity and organic matter sources remain underexplored, especially in freshwater ecosystems. This study identifies the temporal patterns of C-N-P stoichiometry, reveals the inner driving factors, and clarifies its impact path, especially in eutrophication (the late 1970s). The results revealed that sediment RCP and RNP increased significantly and were controlled by TCAR and TNAR, respectively, indicating the direct impact of burial rate on C-N-P stoichiometry. Based on redundancy analysis and the STM model, autochthonous origin, GDP, and population had positive effects on sediment TCAR, TNAR, and TPAR, which, in turn, affected RCN, RCP, and RNP. Organic matter sources and human activities have a significant influence on RCN, RCP, and RNP, possibly regulated by the variation of TCAR and TNAR. Autochthonous origin had an indirect positive impact on RCN and RCP through the mediating effect of TCAR. Similarly, through the mediating effect of TNAR, it had an indirect negative impact on RCN and an indirect positive impact on RNP. This study showed that TCAR, TNAR, TPAR, GDP, autochthonous, allochthonous and population better explained the changes in RCN, RCP, and RNP over a-hundred-year deposition, highlighting an in-depth understanding of the dynamic change mechanism of sediment C-N-P stoichiometry during the lake deposition process.